10th International symposium on Negative Ions, Beams and Sources - NIBS'26

Sep 20, 2026, 2:00 PM → Sep 25, 2026, 1:10 PM America/Vancouver

Conference Room (Prestige Lakeside Resort Nelson)

The 10th International Symposium on Negative Ions, Beams and Sources – NIBS2026 – will be hosted by the Selkirk Ion-source Research Centre (SIRC), and will run from September 20th to September 25th, 2026, in Nelson, British Columbia, Canada. The conference oral presentations and conference dinner will be held at the Prestige Lakeside Resort Nelson, and the welcome wine and cheese and the poster sessions will be held at the Hume Hotel. These hotels are walking distance apart (approximately four blocks).

** Important Notes **:

(i) Official NIBS2026 Invitation Letters for Canadian Visa Applications are only issued once your NIBS2026 registration has been completed and paid.  This is in accordance with Canadian federal government regulations. 

This series of NIBS symposia is conducted biannually starting 2008 and welcomes contributions on any aspect of the production and use of negative ions. The symposium is also an ideal setting to establish contacts and discuss the latest developments in the field of negative ion research.

 

Symposium co-hosted by

 

IOP Conference Series Publication Instructions.pdf

NIBS2026 Award Rules.pdf

Sun, September 20

2:00 PM → 5:30 PM Registration Opens And Sponsor Booth Set-Up

6:00 PM → 8:00 PM Hume: Welcome Wine and Cheese

Mon, September 21

7:45 AM → 8:14 AM Coffee

8:14 AM → 8:15 AM Welcoming Speeches - Chairperson Dr. M. Dehnel & Dignitaries

1) Confirmed - Dr. Maggie Matear, President Selkirk College
2) Confirmed - Dr. Mike Kennefick, Western Regional Director, Mitacs
3) Confirmed - Mr. Richard McElroy, CEO, D-Pace, Inc.
4) Confirmed - Dr. Oliver Kester, Director Accelerator Division, TRIUMF

8:15 AM → 8:20 AM Bring to Order

8:20 AM → 8:30 AM Welcome & Land Acknowledgement - Maggie Matear, President, Selkirk College

8:30 AM → 8:35 AM Mike Kennefick, Regional Director - Pacific, Mitacs

8:35 AM → 8:40 AM Oliver Kester, Director Accelerator Division, TRIUMF

8:40 AM → 8:45 AM Richard McElroy, CEO, D-Pace

8:45 AM → 8:50 AM Priya Biswas, Executive Director, KAST

8:50 AM → 9:00 AM Housekeeping

9:00 AM → 11:00 AM S1: Chairperson -- Lenaic Couedel, U. Marseille

9:00 AM Shedding Light on the Cesium Sputter Ion Source

Accelerator mass spectrometry (AMS) aims at highly efficient and fast detection of minute amounts of radioisotopes and thus crucially depends among others on the attainable negative ion output from a cesium sputter ion source. However, part of the physics behind these work horses remains elusive, prohibiting accurate simulations or even sound predictions of ion source behavior. Generations of scientist have thus experimented with variations of sputter matrix composition, ion source settings and other ion sourcery magic to achieve the best performance of their AMS ion sources.
At the Vienna Environmental Research Accelerator (VERA), possible ion output enhancement by pulsed operation of a NEC-MC-SNICS ion source and by shining laser light into the sputter region has been investigated. Furthermore, spectroscopic analysis of the blue plasma glow visible in front of most sputter targets under favorable ion source output was also performed. Finally, the Ion-Laser InterAction Mass Spectrometry (ILIAMS) setup has been installed, which is capable of selectively removing isobaric contaminants from a negative ion beam via laser photodetachment inside a radiofrequency quadrupole ion guide.

Speaker: Martin Martschini (University of Vienna, Faculty of Physics – Isotope Physics, VERA Laboratory, Vienna, Austria)

9:25 AM Diagnostic Measurements and Performance of the Cesiated H- Source at LANL

The LANSCE H- Ion Source has recently been studied with laser absorption and optical emission spectroscopy diagnostics capable of measuring the in-situ cesium density and temperature, the neutral hydrogen temperature and the $H_{\alpha,\beta,\gamma}$ emission lines. These diagnostics have been installed on the LANSCE production sources for the 2026 run, which presents the first opportunity to see long term trends over multiple sources. Cesium density monitoring will provide data to optimize the Cs conditioning and initial operation of the source, and the Cesium temperature can be used for model validations. The neutral hydrogen temperature and OES measurements will be used to optimize the beam emittance and plasma properties of the source. Comparison of these laser and OES diagnostic parameters with source performance such as beam current, emittance, stability, and lifetime will be presented.
Finally, new diagnostic avenues are being explored, such as the H- Density measurement using Cavity-Ring-Down-Spectroscopy and design of a high-speed laser diagnostic to measure the converter work function in between beam phase pulses. The status of these diagnostics will be presented.

Speaker: David Kleinjan (Los Alamos National Laboratory)

9:50 AM The role of surfaces in high-current negative hydrogen ion sources

The production of negative hydrogen ions (H$^-$/D$^-$) in high-current ion sources occurs through two complementary mechanisms; dissociative electron attachment involving ro-vibrationally excited molecules and low energy electrons, and resonant tunneling of electrons from low work function caesiated metal surfaces to the affinity level of hydrogen atoms. We briefly describe the physics principles of the volume and surface production pathways of H$^−$ ions highlighting the importance of discharge power coupling method and plasma-facing material selection for optimising the H$^−$ yield via vibrational excitation or electron transfer at surfaces. We discuss factors affecting the transition rate of electrons from the bulk material and the survival probability of the surface-produced ions. We predict the relative H$^−$ yield of different caesiated metal surfaces and point out an apparent gap in the availability of data on the band structure and conduction electron density of metals covered by fractional monolayer of caesium, which complicates the comparison. Finally, we make recommendations for experimental and theoretical work on this topic.

Speaker: Olli Tarvainen (STFC)

10:15 AM Application of TALIF for the Characterization of Negative Hydrogen Ion Production in Ion Sources for NBI

The understanding of the surface conversion process of hydrogen/deuterium atoms or positive ions to negative H⁻/D⁻ ions at a low work-function surface is of special interest for the physics of negative ion sources. The negative ion yield from surface conversion is determined by the work function of the converter surface, the flux of the precursor particles (H/D or Hₓ⁺/Dₓ⁺) on the surface and their energy distribution function (EDF). A Two-Photon Absorption Laser-Induced Fluorescence (TALIF) diagnostic is implemented at the negative ion source BATMAN Upgrade (BUG) to determine the density and EDF of neutral hydrogen atoms, which then enables also to calculate their flux on the surface. Recent improvements of the TALIF diagnostic allowed for the first time the resolution and confirmation of a two-temperature EDF of H/D atoms at BUG. To study the precursor particles in detail, TALIF measurements were carried out for the density and EDF of neutrals (H/D) and Mach probe measurements for the flux of positive ions (Hₓ⁺/Dₓ⁺) to the surface. The diagnostic set was completed by diagnostics for H⁻ density, electron temperature/density and optical emission spectroscopy. This contribution discusses the results of the negative ion precursor characterization at BUG.

Speaker: Julian Hörsch (Max-Planck-Institut für Plasmaphysik (IPP))

10:35 AM → 10:40 AM Industry 1, BEST Cyclotron, David Du

10:45 AM → 10:55 AM Coffee

10:55 AM → 12:05 PM S2: Chairperson - Klaus Becker, AMAT

10:55 AM Applications, Developments, and Recent Work with O- Beams

Negative oxygen ion (O⁻) focused ion beams occupy a central role in secondary ion mass spectrometry (SIMS), enabling high-sensitivity analysis of electropositive elements through the ion yield enhancing mechanisms of oxygen bombardment. The implantation of oxygen both increases the ionization probability during the collision cascade and reduces the probability of secondary ion neutralization during the sputtering event, resulting in oxygen ion beams elevating positive secondary ion yields by several orders of magnitude relative to inert primary species.
SIMS with O⁻ beams serve a broad application space including semiconductor process metrology, geological geochronology, nuclear materials characterization, cosmochemistry, and biological studies — all sharing a common requirement for spatially resolved, sub-ppb sensitivity surface chemistry analysis of solid materials.
This presentation reviews the rationale for employing negative rather than positive ion beams, as well as the developments in O⁻ source technology for focused ion beams. Particular attention paid to the transition from legacy duoplasmatron sources to high brightness inductively coupled plasma (ICP) ion sources offering improved brightness, lower axial energy spread, beam current stability, and operational lifetime. Work on ion optical developments, and application results are presented, reflecting a sustained effort to advance spatial resolution, detection sensitivity, and quantitative accuracy of SIMS analysis.

Speaker: Dr Noel Smith (Oregon Physics)

11:20 AM Aspects of negative ions in Microwave PECVD Plasmas for Diamond Thin Film Deposition

Microwave Plasma Enhanced Chemical Vapour Deposition (PECVD) is a versatile technique for thin film deposition. Diamond thin films grown using Microwave PECVD have a wide range of high-tech applications including transparent windows, quantum applications of the diamond NV- centre, thermal transport layers for semiconductor devices, and nuclear battery applications. Our group has been developing microwave PECVD for the deposition of diamond thin films for quantum sensor hardware platforms and semiconductor thermal management applications [1,2]. Deposition of diamond thin films typically proceeds in a 2.54 GHz microwave plasma with a feedstock gas mixture consisting of methane with a large excess of hydrogen. (~1% CH4 / 99% H2). While negative ion formation has generally not been considered in these plasmas, both hydrogen and methane can form negative ions (metastable in the case of anionic methane [3]) and thus the prospect of negative ion formation in H2/CH4 plasmas for diamond film deposition should be considered, both theoretically and experimentally, as the detailed plasma composition is an essential component of repeatable, high-quality film formation. This talk will discuss aspects of negative ions in the context of diamond-thin-film forming plasmas, and their relevance to the deposition and applications of these films.

[1] W. Davis and M. Bradley, “Structural and Optical Analysis of NV Centers in Diamonds Synthesized by MPCVD With Controlled Nitrogen Doping Time”, IEEE Transactions on Plasma Science, 53(10), 2965-2974 (2025). DOI: https://doi.org/10.1109/TPS.2025.3591078

[2] H. Ejalonibu, G. Sarty, and M. Bradley, “The effect of step-wise surface nitrogen doping in MPECVD grown polycrystalline diamonds”, Materials Science and Engineering: B 258, 114559 (2020).

[3] A. Ramírez-Solís, J. Vigué, G. Hinojosa, and H. Saint-Martin, “Solving the CH−4 Riddle: The Fundamental Role of Spin to Explain Metastable Anionic Methane”, Phys. Rev. Lett. 124, 056001 (2020). DOI: https://doi.org/10.1103/PhysRevLett.124.056001

Speaker: Prof. Michael Bradley (University of Saskatchewan)

11:45 AM First Results of a Novel Resonant Antenna Dual-Polarity Focused Ion Beam Source

Advances in focused ion beam (FIB) sources are key to expand the analytical capabilities of secondary ion mass spectrometers (SIMS) while driving down their operational costs, enabling new science in fields ranging from geology, biology, medicine to space sciences [1].

A novel dual-polarity ion source is being developed to equip SIMS with a high-performance, reliable and affordable alternative to existing state-of-the-art sources [2]. The source leverages a novel combination of features to deliver a brightness equivalent to or greater than state-of-the-art negative oxygen ion sources.

The radio-frequency (RF) birdcage resonant antenna favours an efficient inductive plasma generation while minimising the capacitive coupling and associated energy spread [3,4]. A differential bias sheath control scheme enables the production of high-current density negative ion beams from low-power density plasmas. These two key features result in a source design with relaxed constraints regarding thermal and high-voltages management, allowing water to be used as the cooling fluid rather than perfluoropolyethers.

The source performances are characterised by a suite of dedicated diagnostics (Faraday cup, Wien filter, retarding field analyser and scintillators) as well as through test campaigns on Cameca IMS-1280 and NanoSIMS 50L SIMS. With this work focusing on negative oxygen ion beam generation, initial results show a source-side total negative ion beam current density up to 10.7$\,\rm mA/cm^2$ consisting approximately of 63$\%$ O$^-$, 25$\%$ O$_2^-$ and 12$\%$ O$_3^-$. An O$^-$ ion probe of current density $\sim 113 \,\rm mA/cm^2$ with a stability better than 1$\rm \%/h$ and 5$\rm \%/24h$ has been observed on the IMS-1280. First test on the NanoSIMS delivered images of resolution equivalent to state-of-the-art O$^-$ sources.

Speaker: Felicien Filleul (EPFL)

12:05 PM → 1:40 PM Lunch

1:40 PM → 1:45 PM Housekeeping

1:45 PM → 1:50 PM Industry 2: STAC, Jason Taylor

1:50 PM → 1:55 PM Industry 3: Busch/Pfeiffer, Cole Frantz

1:55 PM → 2:00 PM Industry 4: SEF, Eric Fanio

2:00 PM → 3:15 PM S3: Chairperson - Robert Welton, SNS-ORNL

2:00 PM H- Source Developments and Operation at CERN

The Linac4 H⁻ ion source is a critical element of CERN’s operations, directly affecting both accelerator performance and its broad user base. As the sole injector particle source, its reliability and efficiency are essential to the stability of the entire proton accelerator chain and the physics programs it enables. This paper presents an overview of the system, drawing on six years of operational experience. It addresses key aspects including installation and maintenance strategies, spare parts management, the cesiation process, automated RF power regulation, as well as recent upgrades and improvements. Current performance metrics and availability figures are also discussed.

Speaker: Jean-Baptiste Lallement (CERN)

2:25 PM Ion Source Development for AMS at WHOI

Accelerator mass spectrometry (AMS) is a sensitive technique for counting single atoms. The technique was developed in nuclear physics laboratories in the late 1970s for $^{14}$C, and subsequently extended to other isotopes, including $^{10}$Be, $^{36}$Cl, and $^{129}$I. In general, the AMS method employs a positive high-voltage tandem accelerator to accelerate negative ions. Almost exclusively, the negative ions are produced by cesium sputtering sources. Cesium sputter sources have a long history, much of it intimately linked to the development of AMS. Despite nearly five decades of development, the ion source remains the most maintenance-intensive and least understood component of an AMS system. We present some of our efforts to improve the performance of our cesium sputtering source, and additionally, our experience with a novel gas-accepting ECR-type ion source coupled to a charge exchange canal.

Speaker: Dr Mark Roberts (Woods Hole Oceanographic Institution)

2:50 PM Long-lived high-power negative ion beam accelerations update from the CRAFT NNBI test facility

The Comprehensive Research Facility for Fusion Technology (CRAFT) is dedicated to developing core key technologies for future fusion reactors, which incorporates a Negative Ion Source Neutral Beam Injection (NNBI) test facility. The CRAFT NNBI test facility consists of two core test stands: the Hefei Open-facility for Negative-ion Source Research (HONOR), which focuses on experimental investigations of negative ion source characteristics, and the CFETR Advance Neutral Beam Equipment (CANBE), which serves as the prototype neutral beam injector for the Chinese Fusion Engineering Test Reactor (CFETR). To support the R&D on key NNBI technologies, radio-frequency negative ion sources with dual-driver and quad-driver configurations have been independently developed.
Currently, the third experimental campaign of the CRAFT NNBI test facility is in progress, targeting the realization of high-power and long-pulse pure neutral beam on the CANBE test stand. Through systematic optimizations of ion source structure, facility operating performance and experimental operation techniques, the facility has achieved stable high-performance negative ion beam accelerations during the long-term operation (guaranteed ion beam parameters: >180 keV, >2 MW, >200 A/m2, 20~100s). Given that most core components have been in continuous service for more than three years, the negative ion sources were fully disassembled and inspected, with no operational faults detected, verifying the reliable service performance of the device.
On the basis of the above technical breakthroughs, a megawatt-level pure neutral beam was successfully generated for the first time by adopting the residual ion electrical deflection purification technique. Nevertheless, over-current breakdown events occurring on the residual ion dump restrict the continuous and stable purification of neutral beams, which remains a key technical problem to be solved in subsequent research. This paper will elaborate on the latest technical progress, key parameter verification results and existing technical bottlenecks of the CRAFT NNBI facility, providing a reference for the engineering development and performance optimization of high-power long-pulse neutral beam injection systems for fusion reactors.

Speaker: Dr Jianglong Wei (Institute of Plasma Physics, Chinese Academy of Sciences)

3:15 PM → 3:35 PM Coffee

3:35 PM → 4:35 PM S4: Chairperson -Emile Carbone, INRS

3:35 PM PIC Simulation of Negative Ion Beamline for VLEO application

Very Low Earth Orbit (VLEO) missions face strong aerodynamic drag due to the residual atmosphere of highly reactive atomic oxygen, therefore leading to material erosion, making realistic ground tests essential. Numerical simulations are used in advance to optimize the design of its core components to support the development of a dedicated VLEO test facility.

The planned facility generates negative oxygen ions, accelerates them to high velocities, and filters them by species and energy. Electrostatic lenses and a lattice pair then decelerate the particles to the target orbital energy of about 5 eV while maintaining a homogeneous beam. In a final step, a laser removes the electron, producing neutral atomic oxygen for erosion and material testing under representative VLEO conditions.

These processes are modeled with PICLas, an open-source simulation framework for rarefied gas and plasma flows, because experimental development is costly and time-consuming. PICLas combines the direct simulation Monte Carlo (DSMC) method with the Particle-in-cell (PIC) approach, enabling a self-consistent description of particle collisions, charged particle motion, and electromagnetic fields. This approach captures space-charge effects inside the beamline unlike conventional ion-beam propagation tools. The simulations demonstrate a reliable basis for the future experimental setup of the VLEO ground testing facility applied to a realistic negative ion beamline geometry.

Speaker: Kim-Sophie Ellenberger (Institute of Space Systems IRS - University of Stuttgart)

3:55 PM 3D Full-PIC Simulations of a Penning Discharge in Complex Geometries

We present particle-in-cell simulations of a high-current Penning discharge using the semi-implicit electrostatic solver in WarpX [1]. The method reaches experimentally relevant conditions, with discharge currents of several amperes and plasma densities near 1e18 m-3. The modeled 3 A configuration includes two independently biased crescent-shaped anode segments [2]. The simulations show the coexistence of a low-frequency spoke and higher-frequency spiral-arm structures even when the averaged electric field is directed outward. The dominant spoke frequency is about 100 kHz, while spiral-arm structures form over a broadband range near 1 MHz. The anode current shows that the spoke gives the dominant contribution to current oscillations, consistent with experiment [2]. We examine dependence on neutral pressure, magnetic field, anode biasing, and gas composition. Higher neutral pressure suppresses mode activity, shifts the spectrum to lower frequencies, and reduces current noise. Stronger magnetic fields excite additional spoke-like modes and increase current noise. Asymmetric anode biasing reduces instability amplitude, while gas-mixture scans reveal differences in cross-field ion transport.

Speaker: Mikhail Tiushev (University of Saskatchewan)

4:15 PM Analysis of the plasma meniscus in a negative ion source from the viewpoint of force balance

The plasma meniscus and relevant physical structure in the ion-ion plasma of a hydrogen negative source is investigated by using the three-dimensional PIC-Monte Carlo method from the viewpoint of the force balance of negative ions. The simulation results show that the negative ion density along the extraction axis can be divided into two regions based on the electrostatic potential dependence: The one is the plasma region in which the charge neutrality is satisfied by both positive and negative ions, and the negative ion density distribution obeys the Boltzmann relation. The other is the extraction region where the negative ion density is inversely proportional to the power of the electric potential. The separation of positive and negative ions occurs at this boundary, and therefore this boundary corresponds to the plasma meniscus of the ion emitting surface. It is indicated that the potential dependence of the negative ion density as for the plasma meniscus can be explained by the force balance between the electric force, pressure-gradient force. and inertial force for negative ions.

Speaker: Kenji Miyamoto (Naruto University of Education)

5:00 PM → 7:00 PM Poster Session 1

5:00 PM Commissioning of a Penning Ion Source Test Stand and Negative Hydrogen Ion Experiments for Medical Applications

Commissioning of a Penning Ion Source Test Stand and Negative Hydrogen Ion Experiments for Medical Applications

Authors
R. Gagnon$^{2,4,7}$, C. MacKenzie$^{1,2}$, B. Warfield$^{2,3,5}$, J. Doyle$^{1,2}$, S. Spence$^{2}$, M. Morissette$^{2}$,C. Kent$^{2}$, J. Cramton$^{2}$, C. Drew$^{2}$, J. Taylor$^{2}$, T. Junginger$^{3,5}$, S. Tekumalla$^{4}$, N. Savard$^{7}$,A. George$^{7}$, C. Xiao$^{1}$, M. Bradley$^{1}$,G. Fubiani$^{6}$, L. Couedel$^{1}$, O. Kester$^{5}$, M. Dehnel$^{1,2,3}$.

Affiliations

1. University of Saskatchewan — Department of Physics and Engineering Physics
2. Selkirk Ion-source Research Center (SIRC)
3. University of Victoria — Department of Physics and Astronomy
4. University of Victoria — Department of Engineering
5. TRIUMF
6. LAPLACE, Université de Toulouse, CNRS, Toulouse, France
7. D-Pace, Inc.

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Abstract

A Penning ion source test stand is currently undergoing commissioning at the Selkirk Ion-source Research Center (SIRC), establishing the infrastructure for a series of graduate research projects. While the source itself, the vacuum box, and the dipole magnet have been donated by D-Pace, the electrical supply, controls, racks and enclosures, gas supply, and deionized water cooling have all been specified, purchased, and assembled by the SIRC team. The source uses a reversible high-voltage supply capable of ±15 kV cathode bias, with the high-voltage platform fully isolated via an isolation transformer and enclosed in a grounded Faraday cage. A programmable logic controller coordinates the arc and magnet supplies, gas delivery, and cooling system. A de-ionized water system rejects heat from the cathode, anode body, and magnet while maintaining the water resistivity needed for operation at high potential. Vacuum testing and leak detection have been performed to improve the seal and allow pump-down into the high-vacuum regime.
Two cathode research programs will be carried out on the commissioned stand. The first applies Laser Powder Bed Fusion (LPBF) additive manufacturing to produce tantalum cathodes, which will be characterized for beam current and lifetime against conventionally machined cathodes. The second builds on a recent D-Pace and Siemens publication that demonstrated a 20% increase in both H¯ extracted from the internal Penning ion source, and H+ ultimately extracted from the cyclotron with a 30% reduction in arc power by embedding small cesium salt cubes into the Penning cathode surface [1]. A SIRC graduate project will develop and characterize cesium-impregnated cathodes in the controlled test stand environment, quantifying improvements in output beam current, arc power consumption, cathode lifetime, and machine safety.
The primary negative ion beam application is injection into medical Positron Emission Tomography (PET) cyclotrons. Near the outer radius of the cyclotron, the ions pass through a stripper foil and become positive ions before striking PET radioisotope production targets to produce radiopharmaceuticals used in medical diagnostics and therapy. This poster presents the status of the Penning source commissioning and cathode experiments completed to date, as well as a description of the planned experimental program.

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References

[1] Potkins, D., Dehnel, M., Melanson, S., Stewart, T., Jackle, P., Hinderer, J., Jones, N., & Williams, L. (2018). Improvements to Siemens eclipse PET cyclotron Penning ion source. AIP Conference Proceedings, 2052, 050016.https://doi.org/10.1063/1.5083770

Speaker: Connor MacKenzie (Selkirk Ion Source Research Center)

5:20 PM Proof of Concept Work Function Measurements for the LAMP H- Ion Source

At the Los Alamos Neutron Science Center (LANSCE), the LANSCE Accelerator Modernization Project (LAMP) aims to replace the aging front-end, including the H- ion source. The new H- source, based on the RF ion source at SNS, uses a low work function surface for H- ion production, necessary for achieving higher H- current densities. This paper describes simulations and results from a proof-of-concept experiment involving photoemission-based measurements on metallic surfaces—a potential diagnostic for measuring the work function of the LAMP H- ion source.

Speaker: April Smith (Los Alamos National Laboratory)

5:40 PM Progress of the RF H- Ion Source Project at RAL

An RF-driven long-lifetime H- ion source operating at 50 Hz with 1.5% duty factor and 35 keV beam energy is currently under development for the ISIS Neutron and Muon Source at Rutherford Appleton Laboratory. The new ion source is designed operate with an upgraded medium energy beam transport (MEBT) that will provide improved transport efficiency and reduced beam losses. This paper will give an update on the progress made on the project and an overview of the development of the support equipment required for the operation of the ion source with an emphasis on the details of the RF and high-voltage power supply systems.

Speaker: Robert Abel (STFC)

6:00 PM Phase Mixing and Compensation Transitions in Single and Multiple Negative-Ion Beams

Space charge compensation (SCC) is a key process in negative-ion beam transport, because ionization of the residual gas generates secondary charges that can partially or even overcompensate the beam space charge and thereby modify beam transport. Previous studies have shown that the compensation state depends on background-gas conditions, secondary-particle production and loss, and, in multibeam systems, electrostatic coupling among neighboring beamlets. Recent work has further indicated that, in overcompensated regimes, secondary electrons can accumulate and reduce the degree of overcompensation. Motivated by these issues, we formulate a reduced one-dimensional hybrid PIC-MCC model in which one or three prescribed slab-like negative-ion beams are embedded in the transverse coordinate, while beam-born secondary positive ions are treated kinetically.
The aim of the model is not to construct a full beamline predictor, but to isolate the trapping, oscillation, and collisionless phase-mixing dynamics of secondary ions in beam-induced potential wells, and to examine how these ion dynamics interact with electron effects in overcompensated regimes. Within this framework, we test whether phase mixing supports a useful coarse-grained description of the trapped secondary-ion population. In particular, rather than interpreting the redistribution as true thermodynamic thermalization, we introduce an effective ion temperature based on the second moment of the coarse-grained transverse velocity distribution and use it as a reduced descriptor of secondary-ion confinement and escape. This provides a compact way to analyze SCC buildup in the single-beam case. On this basis, we then examine how electron accumulation in overcompensated regions modifies or limits overcompensation, and how electrostatic coupling changes these compensation transitions in the three-beam case. The model is therefore intended to provide a compact, physics-oriented framework for comparing single- and multibeam compensation dynamics, with particular emphasis on the respective roles of trapped ions and accumulated electrons in the onset and limitation of overcompensation.

Speaker: Dr Chen Zuo (Huazhong University of Science and Technology)

6:20 PM Power Electronics for 655kV H- Beam Chopper

Electronic hardware for beam chopping 655kV H- beam at ISIS.

Speaker: Mike RIGG (ISIS STFC)

6:40 PM Alkali-Free Volume Production of He- Ions in Pure Helium Plasma: A Computational Modelling Framework

Tandem accelerators require negative helium He- ions for efficient two-stage acceleration. Currently, He- is produced via charge exchange in alkali metal vapor [1]. This method causes severe issues: downstream contamination, disastrous for semiconductor applications, high-voltage sparking, and hazardous maintenance [2]. We propose transitioning to an alkali-free, volume production method directly within a pure helium plasma. This requires resonant low-energy electron attachment to form He- and it usually involves the metastable He*($1s2s \ , ^3S$ ) state as intermediate step and/or end product for its auto-detachment.
To evaluate potential pathways, we outline a computational framework for the necessary atomic precursor cross-sections. Using R-Matrix or Close-Coupling methods [3], we compute energy-dependent cross-sections for metastable excitation, attachment, and destructive loss channels. Integrating these over the plasma Electron Energy Distribution Function (EEDF) yields macroscopic rate coefficients. These, fed into a 0D global plasma model, can help identify the optimal parameter space that maximizes He- yield, guiding the development of new He- implantation devices.

Speaker: Dr Shubham Singh Baghel (Institut National de la Recherche Scientifique -Énergie Matériaux, Télécommunications)

6:40 PM Development and Experimental Validation of LePIC+ for a Caesium-Free RF Negative Ion Source

We present LePIC+, a new generation Particle-in-Cell code developed from the legacy LePIC code and designed to improve maintainability, scalability, and computational efficiency while preserving the physical fidelity of the original implementation. LePIC+ introduces a fully modernized architecture based on improved memory management and a modular code design. Particular attention was given to the optimization of particle storage and access patterns, resulting in a significant acceleration of the particle mover, one of the most computationally demanding components of PIC simulations. Preliminary benchmarks indicate that LePIC+ is approximately twice as fast as the original LePIC code while producing equivalent physical results. As an initial validation case, LePIC+ has been applied to the modeling of a caesium-free negative ion source (H-/D-) under development at D-Pace. The source employs a 13.56 MHz external RF flat antenna to sustain the plasma. Simulations were performed to obtain plasma density and temperature profiles within the source volume. The numerical results are compared with experimental measurements obtained using an RF-compensated Langmuir probe in the bulk plasma region.

Speaker: Jasmin Deguire (D-Pace, University of Victoria)

6:40 PM Experimental Investigation of Negative Ion Production Mechanisms on Cs-Deposited Metal Surfaces

Negative hydrogen (H$^{-}$) ion production on cesiated metal surfaces is a key process for high-intensity H$^{-}$ ion sources for neutral beam injection systems. Electron transfer from a low-work-function surface to an incident hydrogen atom produces H$^{-}$ ions$^{*}$ near an extraction hole. Semi-continuous Cs supply maintains the low-work-function of the plasma grid (PG)$^{**}$, while intense atomic hydrogen flux on the PG destroys H$^{-}$ ions by associative detachment and can modify the surface atomic structure and near-surface loss processes. The relation between atomic hydrogen flux and H$^{-}$ ion current remains unanswered because positive ions and electrons coexist near the PG surface.
We are experimentally investigating H$^{-}$ ion surface production using an ECR atomic hydrogen source originally developed for biomolecular mass analysis$^{***}$. A Cs-deposited metal target plate simulates the PG, and the H$^{-}$ ion current extracted through the target is measured as a function of atom-source parameters including power, H$_{2}$ flow rate, and duty factor. A Faraday-cup system has shown a clear time-of-flight signal of charged particle flux, and an H$^{-}$ ion detection system with an electron suppressor is being assembled.

Speaker: Yuya Inokuchi (Doshisha. University)

6:40 PM Implementation of Updated Hydrogen and Deuterium Cross-Sections in Particle-in-Cell Simulations of Negative Ion Production in a Volume-Cusp Ion Source

C. MacKenzie$^{1,2}$, J. Deguire$^5$, V. Laporta$^4$, M. Bradley$^1$, G. Fubiani$^3$, L. Couedel$^1$, M. Dehnel$^{1,2,5,6}$.
[1] University of Saskatchewan, Department of Physics and Engineering Physics
[2] Selkirk Ion-source Research Centre (SIRC)
[3] LAPLACE, Université de Toulouse, CNRS
[4] CNR-ISTP
[5] D-Pace, Inc.
[6] Accel-Link Ltd.
Efficient negative hydrogen ion (H⁻) sources are critical for applications including medical cyclotrons used in radioisotope production for diagnostic and therapeutic procedures, as well as neutral beam injection systems in next-generation fusion devices. In these systems, H⁻ ions are primarily generated through collisional processes within the plasma volume of the ion source. In this paper, updated collisional hydrogen and deuterium cross sections from [1] have been incorporated into LePIC [2] for the ITER-Batman ion source case used here as a proxy for D-Pace’s TRIUMF-licensed volume-cusp ion source [3] to better represent the hydrogen plasma behavior and H⁻ production. Volume-produced ions are primarily formed through dissociative attachment (DA), in which low-energy electrons attach to vibrationally excited H₂ molecules, leading to a dissociation into H⁻ and H atoms. As hydrogen molecules undergo interactions with electrons, heavy particles, or plasma-facing surfaces, energy transfer can drive them into higher vibrational energy states. Therefore, the population of vibrationally excited molecules play a critical role in negative ion production, as vibrational excitation has been shown to enhance the probability of DA processes, with molecules in higher vibrational states exhibiting significantly larger cross sections for the DA channel compared to those in the ground state. The updated cross sections utilize reaction channels for the individual vibrational states of molecular hydrogen and deuterium, allowing these states to be resolved within the simulation. Simulation results compare hydrogen plasma's using the legacy and updated cross-section sets and provide an initial comparison of negative ion production dynamics between hydrogen and deuterium cases.

[1] V. Laporta, R. Agnello, G. Fubiani, I. Furno, C. Hill, D. Reiter, and F. Taccogna. Vibrational excitation and dissociation of deuterium molecule by electron impact. Plasma Physics and Controlled Fusion, 63(8):085006,2021.
[2] G. Fubiani et al. New journal of physics. New J. Phys., 19:015002, 2017.
[3] T. Kuo, D. Yuan, K. Jayamanna, M. McDonald, R.Baartman, P. Schmor, G. Dutto (1996). On the development of a 15 mA direct current H- multicusp source. Review of Scientific Instruments. 67. 1314 - 1316. 10.1063/1.1146704.

Speaker: Connor MacKenzie (Selkirk Ion Source Research Center)

6:40 PM Investigation of the work function of the LANSCE H- ion source converter

LANSCE uses a filament driven multi-cusp H- ion source. Most H- ions are produced on a biased, low work function converter. The surface chemistry and work function are complex due to the time dynamics of the pulsed plasma, and the wide variety of elements/molecules that are present and participate in the surface formation. This work will use basic models and existing LANSCE ion source and surface science data to investigate the interplay of these effects.

Speaker: Anna Alexander

6:40 PM Langmuir probe characterization of negative ions in microwave plasmas

Langmuir probes are a well-established and commonly used method for the characterization of plasmas. Basic Langmuir probe measurements focus on electron and positive ion currents while ignoring the possibility of negative ions; however, with certain assumptions, the analysis of the resultant curves can extend to negative ions. Microwave plasmas are important tools for thin film deposition with applications in semiconductor device fabrication and processing, diamond thin film deposition, and many other areas. The quality of films deposited depends on the plasma conditions and so the prospect of negative ion formation, although frequently ignored, should be considered. This poster will present early results and modelling of the possibility of negative ion formation and characterization via Langmuir Probe analysis in 2.45 GHz microwave plasmas operating in regimes suitable for thin film deposition and plasma processing.

Speaker: Portia Switzer (University of Saskatchewan)

6:40 PM Measurement of the Beam Phase Space Structure of the J-PARC Radiofrequency Negative Ion Source by a Double Slit Emittance Meter

In the ITER neutral beam injection (NBI) system, a radiofrequency (RF) negative hydrogen ion source is used to heat the core plasma. However, the current RF ion source has not yet achieved the required beam divergence angle (7 mrad), which remains a major challenge. For the RF negative hydrogen ion source at J-PARC, a large-scale accelerator, the beam distribution has been observed to oscillate at frequencies related to the RF drive under cesium-seeded conditions [1]. Since beam oscillations can increase the beam divergence angle, a more detailed characterization of these oscillations is necessary.
To evaluate the response to RF discharges, time-resolved measurements of the beam phase-space structure were performed using a double-slit emittance meter while simultaneously recording the RF waveform. In the absence of cesium, the phase-space structure exhibited periodic fluctuations, the beam's center of mass rotated, and the emittance oscillated at the RF frequency. These results suggest that the extracted beam is oscillating due to oscillations in the ion source plasma at the beam extraction interface (meniscus). When cesium was added, a distinct additional phase-space structure―not observed in the cesium-free case―was confirmed; this is likely due to the generation of negative ions at the surface.
These measurement results reveal that the beam's phase-space structure exhibits oscillations related to the RF frequency. We plan to conduct similar experiments and analyses using an RF negative hydrogen ion source for NBI.

[1] T.Shibata et al., AIP Conference Proceedings 2373, 050002(2021)

Speaker: Takaaki Ishikawa

6:40 PM Numerical Analysis of Hydrogen Isotope Effects in NIFS-RNIS using KEIO-MARC with a Rate Equation Model

In the Research and Development Negative Ion Source (RNIS) at NIFS, it has been reported that switching the operational gas from hydrogen (H) to deuterium (D) leads to an approximate threefold increase in electron density [1].
In previous studies [2,3], hydrogen isotope effects were investigated using a three-dimensional kinetic electron transport code, KEIO-MARC, together with a rate-equation model. In these studies, two models were integrated, enabling a self-consistent analysis of the electron energy distribution function, the background plasma density and neutral density. Initial results indicated that the electron density in the driver region increased by approximately 10% due to isotope effects [3].
In this study, hydrogen isotope effects were investigated in greater detail. The results revealed that the electron density near the plasma grid (PG) in the D case was up to 2.56 times higher than that in the H case, consistent with experimental observations. In the presentation, the mechanisms underlying the enhanced isotope effects will also be discussed.

Speaker: Hayato Soejima (Keio-University)

6:40 PM Numerical Analysis of Particle Flux Oscillation on Walls of Radio-Frequency Negative Hydrogen Ion Sources

Beam oscillation has been observed in radio-frequency negative hydrogen ion sources (e.g., Ref. [1]). Recently, the oscillation has been investigated using an electrostatic Particle-in-Cell (PIC) simulation, and the behavior resulted from oscillations in the source plasma density [2]. In the simulation, it was assumed that the source plasma in the driver region periodically oscillates, while the surface production rate of the negative ions remains constant. To further understand the mechanism of beam oscillation, this research focuses on plasma kinetics, particularly the fluxes onto the plasma grid (PG), using the electromagnetic PIC Monte Carlo collision code NINJA [3], which incorporates a neutral transport module. The results indicate that the spatially averaged atomic hydrogen flux onto the PG exhibits no periodic oscillation. This suggests that the number of surface-produced negative hydrogen ions per unit time, which are derived from atomic hydrogen, is stable and does not cause the beam oscillation. The presentation will also discuss the behavior of the generated plasma and its influence on the extraction region, including magnetic field and particle energy distributions.

Speaker: Naomi Kawamura (Keio University)

6:40 PM Operation, Performance, and Modeling of a Cesium-Free Negative Hydrogen Ion Source for a BNCT Accelerator

A compact, cesium-free negative hydrogen ion source based on D-Pace hardware has been deployed in a boron neutron capture therapy (BNCT) accelerator at TAE Life Sciences. The cesium-free design fits a medical-accelerator environment well. It avoids the contamination and maintenance burden of cesiated surface-conversion sources, while still meeting the required current and duty cycle. The source runs in both DC and pulsed modes and delivers stable H$^{-}$ beams up to 15~mA. A fully automated control and interlock framework enables hands-free operation throughout clinical routines. Operational parameters and diagnostics are logged continuously, which supports real-time monitoring, trend analysis, and long-term reliability assessment.

In this contribution we first summarize the recent operational performance of the source on the BNCT machine, with a focus on stability, reproducibility, and availability during routine clinical use. We then present an in-house experimental campaign that characterizes the source under controlled conditions, together with complementary simulation efforts. The simulations include beam-optics modeling of the existing extraction geometry, particle-in-cell modeling of downstream beam propagation, and an in-house treatment of beam--gas interaction losses. Together, these tools provide physical insight into the observed behavior and guide optimization of the source and its low-energy transport line.

The operational record and the in-house study together form a consistent picture of the performance and limitations of a cesium-free H$^{-}$ source in a given medical-accelerator setting.

Speaker: Vladislav Vekselman (TAE Technologies)

6:40 PM Optimization of Puller Offset from Plane of Plasma Extraction for H¯, 4He 2+, and 18O 3+ Ions

In Penning ion source design the puller electrostatic lens, nominally biased at ±15 kV for
the SIRC test stand, is offset from the plane of initial beam extraction from the plasma
chamber’s anode aperture centreline in order to account for the Lorentz force imparted
by the dipole magnetic field. A study of how this offset can be optimized to limit beam
loss and increase acceptance is done using IBSimu [1] beam modeling software and
phase space analysis for the case of several extracted ions of different mass and
charge state. The specific ions considered for this study are H¯, 4He 2+, and 18O 3+ at
+15kV and -15KV extraction bias voltages, respectively. The shape and geometry of the
puller slit are also investigated for beam performance improvement. The results will aid
in the operation of the Penning ion source test stand under development at the SIRC.

Speaker: Ben Warfield (University of Victoria)

6:40 PM Status on the TRIUMF's new 300 keV H- injection system

The demand for extracted beams from TRIUMF's 500 MeV cyclotron is growing with the addition of ARIEL, its new advanced rare isotope beam facility. To meet these intensity requirements, an upgrade program has been initiated for the injection system. The program involves installing a new injection beamline and an additional ion source to enable high-brightness, intense beam injection. Commissioning of the new beamline is complete, and integration of the additional ion source is in progress. The existing ion source had critical limitations: initial beam energy was capped at 12 keV, and filament power at 2.5 kW, resulting in short filament lifetimes. A new source will be developed to produce a high-brightness $25~\rm{keV}~\rm{H}^{-}$ beam with significantly extended filament lifetime. A specialized transport system uses magnetic optics to maintain space-charge neutralization. The status of this upgrade program will be presented.

Speaker: Suresh Saminathan (TRIUMF)

6:40 PM Study on Key Technologies for Laser Neutralization based Negative Ion Beams

As magnetic confinement fusion advances toward power generation, neutral beam injection (NBI) auxiliary heating faces increasingly stringent demands for higher energy, current density, and pulse duration. Ion beam neutralization—the most critical step in NBI—currently relies on the gas target method, where ions collide with homogeneously injected gas to produce neutrals. While raising the gas target thickness can boost neutralization efficiency to ~60%, this imposes excessive vacuum loads and degrades beam transmission. In contrast, the laser target method introduces no additional gas and achieves theoretical neutralization efficiencies exceeding 90%, representing a key breakthrough for NNBI development. This work addresses critical technical challenges in laser neutralization test platforms for negative ion beams, including: generation and transport of flat rectangular ion beams, stable operation of multi-folded resonant cavities, and predictive analysis of photothermal effects. In accordance with a small-scale laser neutralization test platform, a single-aperture radio frequency (RF) H⁻ ion beam transmission system was built with the integration of relevant NBI functional components, which outputs a Gaussian H⁻ beam with 50 keV@35 A/cm², and the beam cross-section presents as rectangular beam spot with adjustable dimensions. Adopting the resonant folded optical path approach, the configuration parameters of a triangular ring cavity (n=3) and a butterfly ring cavity (n=4) were obtained, which are applicable to full-scale NNBI devices and small-scale test systems. Combined with the Pound-Drever-Hall (PDH) technology, a stably operable butterfly cavity was designed and constructed, with a finesse of approximately 1150 and a laser waist radius of about 130 μm. The beam spot radius w(z) in the remaining optical path ranges from 600 to 700 μm, with an ellipticity of approximately 1.36%. A physical model of the photothermal effects of lenses and high-reflectivity mirrors was established based on the optical-thermal-structural coupling, and the variation law of the thermal damage parameters of the butterfly cavity was calculated, which is consistent with the experimental results of the sample mirror temperature rise. Meanwhile, the curve fitting results can also be used to predict the damage time and damage degree.

Speakers: Dr Huihui hong, Yuanlai Xie

6:40 PM The Use of Simulation Software to Predict the Expected Pressures within the Internal Plasma Chamber of a Penning-Ion Source

S. Spence¹, C. MacKenzie^1,2, R. Gagnon^1,4, B. Warfield^1,3, M. Morissette¹, M. Dehnel^1,3

1. Selkirk Ion-source Research Centre (SIRC)
2. University of Saskatchewan, Department of Physics and Engineering Physics
3. University of Victoria, Department of Physics and Astronomy
4. University of Victoria, Department of Mechanical Engineering

Abstract

The Selkirk Ion-source Research Centre (SIRC) is in the process of assembling and commissioning a Penning ion-source test stand for a series of graduate research projects. Measuring the internal pressure of the Penning plasma chamber will be estimated by calibrating MolFlow [1] simulations with vacuum gauge measurements on the overall test stand vacuum chamber.
A Computer-Aided Design (CAD) file of the vacuum box and Penning source was created and imported into MolFlow, where geometry is represented as a series of polygons and facets, with the appropriate testing parameters applied to the system. Each internal face has an applied outgassing rate that is consistent with the material of the specified facet. The turbo-molecular pump is denoted with its pumping rate as specified by its manufacturer. With these parameters, the internal pressures of the system can be simulated over time and exported as a table of values or a pressure gradient map. The simulation results will be compared with pressure gauge readings of the actual vacuum system. Comparing the gauge readings of the vacuum system with the simulated pressure calculations within MolFlow will permit simulation iterations with modified outgas values to achieve a model that correlates well with the measured vacuum values in the overall test stand vacuum chamber, which will be described in this poster/paper. Next a MolFlow simulation campaign will be described, in which pressure values inside the 8 mm diameter by 50 mm tall cylindrical Penning ion source are obtained at various Nitrogen and Hydrogen gas flow rates. This pressure data will serve as inputs for Particle-In-Cell (PIC) models of the Penning plasma and support the development of N⁵⁺ and negative Hydrogen ion beam production.

Speaker: Sydney Spence (Selkirk Ion-source Research Centre)

8:00 PM → 9:00 PM NIBS2028 Proposal Presentations to IAC

Tue, September 22

7:45 AM → 8:00 AM Coffee

8:00 AM → 8:10 AM Housekeeping

8:10 AM → 9:45 AM S1: Chairperson - Vincenzo Laporta, ISTP-CNR

8:10 AM Advanced Negative Ion Source concept for Neutral Beam Injectors

The negative ion source currently being developed for the ITER neutral beam injector (NBI) suffers from two fundamental design shortcomings: (i) a plasma asymmetry along the direction parallel to the plasma grid, and (ii) an excessively elevated plasma potential that may degrade beam divergence within the accelerator. To overcome these issues, we propose a novel source architecture designated ANIS (Advanced Negative Ion Source).
Negative ions for fusion applications are produced in a two-stage system comprising an ionization chamber followed by a magnetized expansion region, the latter serving to reduce electron temperature and flux at the extraction zone. In current RF-driven sources, a dipolar magnetic field topology drives an electron Hall drift toward one of the lateral walls, polarizing the plasma and generating a transverse electric field that results in asymmetric distributions of plasma density, temperature, and potential [Fan14, Zie21]. Additionally, at the low operating pressures anticipated for ITER (~0.3 Pa), the plasma potential can reach up to 70 V, promoting the formation of energetic neutrals and negative ions that broaden beam divergence [Wim24].
The ANIS concept addresses these limitations through two principal design innovations: (i) a closed electron drift magnetic configuration that suppresses the Hall effect and enforces axisymmetric plasma profiles; and (ii) electrodes placed at the magnetic mirrors within the discharge region to independently control both the magnitude and spatial gradient of the plasma potential, thereby shaping the energy distribution function of neutrals (which are precursors to the production of negative ions on cesiated surfaces), and improving beam optics.
Three-dimensional Particle-In-Cell Monte Carlo Collision (PIC/MCC) simulations [Fub17, Fub14] confirm that the ANIS magnetic geometry produces axisymmetric plasma profiles and a markedly reduced plasma potential. The magnetic topology is also shown to be tunable via concentric permanent magnets or coils, providing a versatile platform for systematic parametric studies of plasma transport.
This work presents both the numerical characterization of the plasma behaviour and the associated experimental program.

References
[Fan14] U. Fantz et al., Plasma Sources Sci. Technol. 23 (2014) 044002
[Fub17] G. Fubiani et al., New Journal of Physics 19 (2017) 015002
[Fub14] G. Fubiani et al., Phys. Plasmas 21 (2014) 073512
[Wim24] C. Wimmer et al., Journal of Physics: Conference Series 2743 (2024) 012033
[Zie21] D. Zielke et al., J. Phys. D: Appl. Phys. 54 (2021) 155202

Speaker: Gwenael Fubiani (LAPLACE, Universite de Toulouse, CNRS)

8:35 AM Simulation and Experimental Study on the Ejected Electrons from Negative Ion sources on the CRAFT NNBI test facility

In the accelerator of negative ion source, electrons are easily generated via stripping loss of negative ions, background gas ionization, and secondary electron emission from electrodes. Under the effect of electric and magnetic fields, these electrons acquire high energy and exhibit a large divergence angle. Once ejected from the ion source, the energetic electrons can directly strike on the downstream beamline components, and especially exert a fatal impact on the thermally sensitive cryopumps. To address this issue, actively cooled electron dumps have been designed in devices such as JT-60U, LHD, and ITER to intercept the ejected electrons.
Based on a multi-physics coupling model of the negative ion source accelerator, the ejected electrons from the CRAFT dual-driver and quad-driver negative ion sources are characterized. Several sets of electron dumps were designed and installed in the CANBE, one of the test stands of the CRAFT NNBI test facility. In recent negative ion beam acceleration and neutralization experiments on CANBE, the water flow calorimeter (WFC) and infrared camera were used to measure the total deposited power and two-dimensional temperature distribution on the electron dumps, respectively. The thermal deposition characteristics were analyzed under different experimental conditions. Furthermore, the multi-physics coupling model was used to simulate ejected electron transport and deposition under realistic operating conditions, including beam energy, beam current, beam profile and gas pressure. Through a comparative analysis of the peak position and spread of thermal deposition between simulations and experiments, the model was further calibrated and optimized.

Speaker: yuwen yang (Institute of Plasma Physics, Hefei Institutes of Physical Science, Chinese Academy of Sciences)

8:55 AM Conceptual design of a negative-ion-based neutral beam module for an FRC reactor prototype.

In a future fusion reactor prototype under development at TAE Technologies, Inc., negative-ion-based neutral beams with a total power of 20 MW are used to sustain the p-B reaction in the plasma. The neutral beam system will comprise four injector modules, each capable of producing a 5 MW, 1 MeV steady-state neutral beam. The conceptual design of the injector module features a spatially separated ion source and an electrostatic accelerator. A photon or plasma neutralizer of the negative-ion beam will be employed to achieve an overall system energy efficiency of up to 80%. The distinct features of the negative-ion source, accelerator, and beam-duct elements are discussed. The ion source prototype is designed at about ½ scale of the final ion source to study options for the plasma box, which employs either microwave or hot-filament gas discharge, and for the grid system. It is intended to produce a 120 keV, 3 A negative-ion beam when operated in either the volume or surface negative-ion production regimes. The prototype’s design and the main goals of its studies are also briefly reviewed.

Speaker: Prof. Alexandr Ivanov (TAE Technologies)

9:20 AM Alternative Solution to Address the Challenge of Negative Ion Sources for Fusion

The project addresses a critical challenge in fusion energy: replacing caesium (Cs) in negative-ion (NI) sources for Neutral Beam Injectors (NBIs), which are essential for heating and driving plasma current in tokamaks like ITER. While Cs is effective, it poses maintenance and safety issues due to its reactivity and accumulation, which would be problematic in nuclear environments. This work aims to validate an innovative, Cs-free NI source, paving the way for next-generation fusion reactors and broader applications in accelerators and plasma catalysis. The approach involves using alternative low-work-function materials (e.g., diamond, C12A7, or gadolinium) and injecting them as micro-particles into the plasma. These micro-particles, transiting through the plasma, would continuously renew the surface for NI production while avoiding contamination.
The first part of the project explores NI production and extraction from low-work-function material surfaces. We focus on optimising conditions for NI production (e.g., surface potential, magnetic field). This requires developing advanced diagnostics for NI flux measurements, such as a Magnetised Retarding Field Energy Analyser (MRFEA), as well as surface analysis of the studied materials (UPS/XPS, Raman).
The second part focuses on fundamental studies of argon/hydrogen plasmas containing micro-particles. Using a capacitively coupled RF discharge, we investigate how NI emission from micro-particle surfaces influences their charge, floating potential, and transit time, key parameters for efficient NI extraction. Techniques include laser-induced wave propagation in 2D micro-particle monolayers and trajectory analysis of falling particles, correlated with plasma diagnostics (Langmuir probes, LIF, mass spectrometry).

Speaker: Lenaic Couedel (CNRS/Aix-Marseille Université)

9:45 AM → 9:50 AM Industry 5: Richard McElroy, D-Pace

9:50 AM → 9:55 AM Industry 6: Seth Veitzer, Silvaco

9:55 AM → 10:00 AM Industry 7: James Titus, TAE

10:00 AM → 10:05 AM Industry 8: Dominick Bindl, Realta Fusion

10:05 AM → 10:25 AM Coffee

10:25 AM → 12:55 PM S2: Chairperson - Gwenael Fubiani, U. Toulouse/CNRS

10:25 AM Theoretical Vibrational-excitation Cross Sections for PIC Based Negative Ion Plasma Computations

Accurate state-resolved electron-molecule cross sections are essential for the quantitative description of low-temperature plasmas, negative ion sources, and neutral and charged particle beam systems. In particular, vibrational excitation processes induced by electron impact play a crucial role in determining molecular energy distributions, dissociative attachment rates, and the production efficiency of negative ions in hydrogen and hydrogen-containing plasmas. These mechanisms are directly relevant to the operation of high-current negative ion sources used in present and future fusion devices.

In my contribution I will present recent advances in the determination of electron-molecule vibrational excitation cross sections, with emphasis on resonant scattering processes and their impact on negative ion formation. Theoretical calculations and available experimental benchmarks will be discussed for molecular targets of relevance to plasma processing and fusion applications. Particular attention is devoted to the coupling between vibrational kinetics and dissociative electron attachment, which governs the generation of H⁻ and D⁻ ions in plasma sources.

Speaker: Vincenzo Laporta (Istituto per la Scienza e Tecnologia dei Plasmi - CNR)

10:50 AM Metastability of H$^-$ and O$^-$ Negative Ions at the Nanosecond Timescale

Electron autodetachment of negative ions is a known phenomenon at the picosecond and shorter time scales. Examples are shape or Feshbach resonances observed in electron scattering. However, experimenters have observed autodetaching phenomena in longer time scales. These observations have not been independently confirmed because of the
difficulty of isolating negative ions and, because radiative decay on the nanosecond scale is difficult to measure from an ion beam. In this work, we present two conceptually new methods to engage the study of metastable states of negative ions. A theoretical method that is based on discretized pseudospectra under the analytic continuation
of Green's function of the Fano-Feshbach formalism and, a experimental method based on the time-dependent extension of the solutions to the fraction-equilibrium equations for the electron detachment cross sections. Results on H$^-$, O$^-$ and O$_2^-$ will
be presented.

Speaker: Guillermo G. Hinojosa Aguirre (Universidad Nacional Autonoma de Mexico)

11:15 AM Caesium Free Negative Ion Beam Developments using Microwave Heating of Low-Work Function Materials

Caesium-free negative ion sources have been actively studied to reduce vacuum contamination and improve maintainability. Such demands are increasing beyond neutral beam injection systems, including accelerator mass spectrometry (AMS). In AMS, 2 m × 2 m scale $^{14}$C systems for wider use are being developed $^{1)}$, increasing interest in safer caesium-free operation compared with conventional caesium sputter sources.

One possible approach is surface negative ion generation using low-work-function (low-φ) materials. A major issue is surface contamination with adsorbates, which increases the work function and reduces ion production efficiency. The author has investigated microwave heating of granular low-φ materials as a possible solution.$^{2)}$ Since microwave heating of conductive materials is mainly limited to the skin-depth region, the use of granules can increase the heated area contributing to negative ion production.

Proof-of-concept experiments using LaB$_6$ granules and methane gas confirmed production of carbon molecular negative ions.$^{2)}$ However, experiments using CO$_2$ revealed carburization and oxidation of the LaB$_6$ surface, suggesting that surface reactions may become an important issue under CO$_2$ atmospheres. Based on these results, we are extending this low-φ material approach toward helium negative ion generation for industrial applications.
................
$ ^{1)}$ S. Jinno, A. Matsubara, N. Fujita, K. Kimura, Nucl. Instr. and Meth. B 557, 165545 (2024).
$^{2)}$ A. Matsubara, Y. Kokubu, K. Nishio, K. Kimura, K. Kashimura, K. Shimada, N. Fujita, Nucl. Instr. and Meth. B 568, 165863 (2025).

Speaker: Dr Akihiro Matsubara (PESCO Co., Ltd)

11:40 AM Fulcher-Alpha Spectra and Laser Photodetachment Measurements and Models at SNU $H^-$ Source

To improve the performance of volume production-based negative hydrogen ion sources, it is crucial to understand the negative ion volume production reactions by vibrationally excited molecules and cold electrons. This requires a thorough understanding of electron kinetics within the plasma, the generation and relaxation processes of vibrationally-excited molecules, and the transport of neutral particles across the magnetic filter.
In this work, we first review the core diagnostic techniques and physical analytical models established in the radio-frequency (RF) $H^-$ ion source research at Seoul National University (SNU). Fulcher-alpha band spectroscopy was utilized to analyze the changes in the vibrational distribution function (VDF) of hydrogen molecules and the behavior of neutral particles passing through the magnetic filter region. Additionally, the laser photo-detachment technique was applied to precisely measure the $H^-$ ion density in the plasma. Based on these diagnostic results, a zero-dimensional (0D) particle balance model and a one-dimensional (1D) neutral particle transport model were combined to successfully elucidate the production and destruction mechanisms of negative ions according to varying pressures and RF powers.
Building on these diagnostic foundations, we highlight two recent studies maximizing plasma confinement in Korea. First, SNU's recent research utilizes the double-layer potential of an anode spot plasma to induce inflow and confine negative ions, significantly enhancing local density. Second, KAERI’s Two-Region Arc Plasma (TRAP) source maximizes volume production efficiency by physically separating the high-energy driver region and low-temperature extraction region using movable filaments and optimized magnetic fields.

Speaker: Jeong-jeung Dang (Korea Institute of Energy Technology (KENTECH))

12:05 PM Impact of plasma potential modifications on the performance of ITER-relevant negative hydrogen ion sources

The test facilities BATMAN Upgrade with a $1/8$ ITER-size ion source ($0.3\times0.6\,\mathrm{m}^2$) and ELISE with a half ITER-size ($1\times1\,\mathrm{m}^2$) source are essential parts of the European Roadmap towards the ITER NBI system (size of the ion source $1\times2\,\mathrm{m}^2$). These sources rely on the production of negative ions on caesiated low-work function surfaces. The ion source for ITER NBI should deliver a high current density of extracted negative ions ($329\,\mathrm{A}/\mathrm{m}^2$ in hydrogen, $286\,\mathrm{A}/\mathrm{m}^2$ in deuterium) for up to one hour at an electron-ion ratio below one and highly homogeneous ($>90\,\%$) over the extraction area.
Refined caesium conditioning techniques, a modified magnetic filter field topology and/or modified electrostatic potentials in the plasma enabled for the very first time long pulses with $90\,\%$ of the ITER target for the extracted negative ion current density both in deuterium (at BATMAN Upgrade) and in hydrogen (at ELISE). The achievable performance typically is limited by the amount, asymmetry and temporal increase of the co-extracted electrons.
Presented and discussed are investigations on the interplay between electrostatic potentials close to the plasma grid and the co-extracted electrons. The impact of additional biased surfaces like the potential rods influencing at ELISE the electron flux towards the plasma grid is investigated both in hydrogen and deuterium. The ELISE bias plate was set to different potentials, including the plasma grid potential. The latter is a test for completely removing the bias plate which is planned for the second half of 2026 on request by ITER IO.

Speaker: Dirk Wünderlich (Max-Planck-Institut für Plasmaphysik (IPP))

12:30 PM → 1:50 PM Lunch

1:50 PM → 3:20 PM S3: Chairperson - Nikolai Lobanov, ANU

1:50 PM How Low Can we Go? Routine Reliability and Low Energy Limits for AMS with a Cs Sputter Source

Accelerator mass spectrometry (AMS) is a highly sensitive technique for the detection of long-lived radionuclides and rare isotopes, with applications spanning archaeology, earth sciences, environmental studies, biomedicine, and nuclear science. AMS systems rely on the production of stable negative ion beams, most commonly using Cs sputter ion sources, followed by acceleration and molecular suppression to enable high-sensitivity isotope measurements. The output efficiency, stability, and operational reliability of the ion source therefore play a central role in the overall efficiency and reproducibility of AMS measurements.

This invited contribution will present an overview of the ETH-developed Cs sputter source systems, including improvements in low-maintenance operation, beam stability, and reproducibility. Operational experience from routine AMS applications and recent source optimisation efforts will be discussed.

The presentation will then focus on ongoing studies exploring the low-energy operating limits of the Cs sputter source, motivated by future injection into an ion cooler forming part of a new isobar suppression system. Measurements and ion-optical calculations of the extracted beam phase space are being used to investigate beam properties and matching conditions at reduced extraction energies.

These studies provide insight into the practical limits of low-energy operation of the ETH Cs sputter source and the associated trade-offs in beam output and emittance. The results are intended to inform the future integration of sputter sources with ion cooling and photodetachment systems, and to guide the development of low-energy beam transport schemes for next-generation AMS applications.

Speaker: Lauren Bezzina (ETH Zürich)

2:15 PM The Effects of Laser Irradiation and Source Parameters on the Cathode Temperature and Negative Ion Production in MC-SNICS ion source

The negative ion formation in caesium sputter ion sources occurs on the surface of a cathode covered by a thin caesium (Cs) layer that lowers the surface work function and enhances the negative ion yield. It has been demonstrated that laser irradiation of the cathode can significantly increase the extracted negative ion current. The laser enhancement often exhibits a transient nature suggesting that the irradiation affects the caesium coverage of the cathode.

In this work we investigate the effects of laser irradiation, Cs+ ionizer power, and cathode voltage on the cathode temperature, cathode current, and Cu− beam production in a Multi-Cathode Source of Negative Ions by Caesium Sputtering (MC-SNICS). It is shown that the beam current correlates strongly with the cathode temperature, which determines the desorption rate of caesium from the sputter target surface. It is concluded that laser irradiation, ionizer power, and cathode voltage strongly influence the Cs coverage on the cathode surface, which is essential for optimized negative ion production, and thus explains the earlier observations where the laser exposure has been shown to boost the extracted beam currents.

Speaker: Dr Mikko Laitinen (University of Jyväskylä)

2:35 PM Correlation Between Plasma Parameters and Beam Characteristics in a RF-driven negative hydrogen ion sources

In cesiated radio-frequency (RF)-driven negative ion sources, beam divergence and spatial uniformity are strongly influenced by plasma transport processes and cesium dynamics in the source region. Since beam quality is closely linked to plasma behavior near the plasma grid, understanding the coupling between source plasma properties and extracted beam characteristics is essential for optimizing high-current negative ion beam systems. However, the quantitative relationship between source-region optical emission spectroscopy (OES) observables and beam properties remains insufficiently understood.
This work presents an integrated multi-diagnostic framework to investigate the correlation between plasma parameters and beam characteristics on the CRAFT RF-driven negative hydrogen ion source test facility. Balmer-series emissions (Hα, Hβ, and Hγ) measured near the plasma grid are analyzed to derive spectroscopic indicators associated with local plasma behavior. Effective plasma parameters are inferred using an ADAS-based collisional-radiative model, enabling the characterization of plasma conditions relevant to negative ion production and transport.
Beam properties, including divergence and spatial uniformity, are characterized through the combined use of beam emission spectroscopy, visible-light imaging, water-flow calorimetry, and secondary electron diagnostics. Plasma and beam observables acquired under varied operating conditions, including variations in source and extraction parameters, are synchronized to establish a source-beam parameter database for systematic correlation analysis.
The study seeks to improve the understanding of source-beam coupling mechanisms in cesiated RF-driven negative hydrogen ion sources and to support the development of spectroscopy-assisted diagnostic and optimization strategies for negative hydrogen beam systems relevant to neutral beam injector applications.

Speaker: Dr Na Wang (ASIPP.CAS)

2:55 PM Tracing Ultra-Low Level Environmental Processes using Negative Ion Beams of Rare Isotopes

Movements of nuclear contamination through the world's oceans, and natural radioactive decay in ancient deep-subsurface ground waters, can be traced by $^{127}$I/$^{129}$I and $^{236}$U/$^{238}$U isotopic composition (IC) measurements. Accelerator mass spectrometry (AMS) remains the technique of choice for such IC determinations at ultra-trace levels (i.e. $<$ 1$\times$10$^{-13}$), with a key requirement that long-lasting high current negative ion beams of those elements must be produced from solid samples in Cs$^+$ sputter-ion sources. Here, I discuss ion source and sample chemistry developments that significantly increased negative ion currents of $^{129}$I and $^{236}$U on the 3 MV tandem AMS at uOttawa, allowing precise and accurate $^{127}$I/$^{129}$I and $^{236}$U/$^{238}$U IC determinations in waters from (A) the Beaufort Sea (Arctic Ocean) between 0 to -4000 m depths for tracing the movements of nuclear reprocessing waste, and (B) Kidd Creek Mine (Timmins, ON) at $\sim$8000 ft depth, to identify radioactive decay as a radiolytic energy source in the world's oldest known isolated ground water.

Speaker: Christopher Charles (TRIUMF)

3:20 PM → 3:25 PM Houskeeping

3:25 PM → 3:45 PM Coffee

3:45 PM → 4:35 PM S4: Chairperson - Olli Tarvainen, STFC UKIRI

3:45 PM The high-density core of compensating Hminus beams

Recent particle in cell simulations of space change compensation in high current Hminus beams clearly demonstrate the formation of a high-density core in space charge compensating Hminus beams. Evidence of this phenomena has also been experimentally observed.

Speaker: Dan Faircloth (UKRI STFC ISIS)

4:10 PM DESIGN OF A NEGATIVE OXYGEN BEAMLINE FACILITY FOR EXPERIMENTAL VERY LOW EARTH ORBIT SIMULATION

There is a rapidly growing interest in operating satellites in very low Earth orbits (VLEO, $200$-$450$ km). These orbits support efficient communication and Earth observation and offer short post-mission lifetimes due to rapid reentry, reducing the risk of orbit contamination compared to conventional LEO ($>500$ km). The environment is dominated by atomic oxygen, and atmospheric drag and erosion remain primary challenges. At the same time, the residual atmosphere can be used for propulsion and lift. Experimental validation of appropriate concepts requires ground-based facilities reproducing VLEO conditions: neutral atomic oxygen fluxes with a kinetic energy of around $5$ eV and a density of around $10^{9}\,\mathrm{cm^{-3}}$.

This work presents a new test facility design based on a negative oxygen ion beam. An RF plasma source initially generates $\mathrm{O_2^-}$ and $\mathrm{O^-}$ ions in the keV range, which are either magnetically filtered using a dipole magnet or velocity filtered in an $E \times B$ field (Wien filter) to obtain pure $\mathrm{O^-}$. The beam is then decelerated to target energies using an ion-optical system designed to minimize divergence under space-charge effects. Immediate downstream neutralization is achieved via laser photodetachment, enabling contactless conversion without momentum transfer. Residual ions are removed magnetically.

The development work presented focuses on the deceleration unit, ensuring low-divergence beam transport at high currents. Configurations such as ring electrodes, resistive tubes, and combined electrode-grid systems were studied, including aperture control. The design process is supported by numerical simulations of the individual components, carried out using the PICLas code, which enables self-consistent modelling of space-charge effects. Using this approach, a configuration has been developed that meets the defined requirements, demonstrating the feasibility of the proposed concept.

Speaker: Lasse Voigt (Institute of Space Systems - University of Stuttgart)

5:00 PM → 7:00 PM Poster Session 2

5:00 PM The LAMP H- ion sources: goals, status, and plans

The LANSCE Accelerator Modernization Project (LAMP) will replace the front-end of the existing LANSCE accelerator, from ion sources through the end of the 100-MeV drift-tube linac. This work will describe the H- ion source and injector requirements for LAMP. It will also describe plans for and progress towards the commissioning and testing of the LAMP H- ion testing, as well as various test stands that are being built for this purpose, in particular the RFQ test stand (RFQTS) and LAT (Lamp in ADEF tunnel).

Speaker: Anna Alexander

5:20 PM High-intensity RF-driven cesiated negative hydrogen ion source equipped with J-PARC-made antenna coil for J-PARC user operation

It has been over a decade since J-PARC initiated negative hydrogen ion beam (H$^-$ beam) supply from its high-intensity radiofrequency-driven H$^-$ ion source in the autumn of 2014. It is noteworthy that there have been virtually no major incidents to date, with only three instances of operational shutdowns and replacement work due to damage to the antenna coils. The operation of the ion source equipped with the J-PARC-made antenna coil was initiated for J-PARC users in autumn 2025 subsequent to the execution of the various off-line tests and then receipt and successful completion of the J-PARC internal review. The ion source extracts the H$^-$ beams with a beam current of 62.5 mA to fulfil the requirement of 50-mA H$^-$ beam current at the end of the linac and a beam energy of 52.5 keV for appropriate injection into the RFQ. The presentation provides an account of the operational status of the J-PARC high-intensity, RF-driven cesiated negative hydrogen ion source from autumn 2025 to summer 2026.

Speaker: Katsuhiro Shinto (J-PARC center / Japan Atomic Energy Agency (J-PARC/JAEA))

5:40 PM Design Evolution and Performance Improvements of D-Pace's ES-4 Emittance Scanner

An emittance scanner is one of the most valuable diagnostic instruments available to a low-energy beam transport (LEBT) system. D-Pace licensed an Allison-type emittance scanner from TRIUMF and commercialized the design in 2013. Over the course of the subsequent 13 years, the ES-4 emittance scanner has undergone a series of incremental hardware and software upgrades aimed at improving measurement accuracy, reliability, and operational flexibility. The upgrade program included comprehensive design modifications, the development of a new 10 kW, 100 mm beam-diameter emittance scanner probe, an upgraded scanner control system, and measurement synchronization with pulsed beam operation. The upgraded scanner now provides expanded capability to accommodate more demanding beam conditions. This work summarizes the key design changes over the years and highlights the impact of the upgrades on system performance.

Speaker: Mr Zack Watkins (D-Pace)

6:00 PM Addressing Plasma Asymmetry and Potential Control in the Negative Ion Source for Neutral Beam Injectors: the ANIS Concept

The negative ion source concept currently under development for the ITER neutral beam injector exhibits several design flaws, notably: (i) plasma asymmetry along the direction parallel to the ion extraction grid, caused by the transverse magnetic configuration inducing an electron drift (Hall current) that is intercepted by one of the lateral walls (Hall effect), [1, 2] and (ii) an excessively high plasma potential, which is believed to adversely affect beam divergence in the accelerator. The objective of this study is to propose a novel ion source concept that addresses these fundamental issues. This novel ion source termed ANIS (Advanced Negative Ion Source) is currently under development at Laplace.
The proposed approach is primarily based on modifying the magnetic field configuration to both eliminate the Hall effect (by closing the electron drift path – forming a closed, wall-free drift loop – and thereby removing plasma asymmetry) and control the plasma potential amplitude (and its gradients) using electrodes positioned at the magnetic mirrors in the discharge region, thereby influencing the energy distribution of negative ions and improving beam optics.
Experimental results obtained on ANISette, a reduced-scale prototype of ANIS with a custom-built magnetized RF source featuring a radial magnetic field configuration, will be presented alongside three-dimensional (3D) particle-in-cell (PIC) simulations. The magnetic field topology can be tuned using coils, enabling detailed parametric studies of plasma transport mechanisms. Our observations show that the plasma parameters – density, electron temperature, and plasma potential – exhibit axisymmetric and relatively flat profiles in the expansion chamber. Moreover, the plasma potential amplitude can be effectively controlled by biasing electrodes placed at specific locations along the wall in the ionization chamber.
[1] F. Gaboriau, R. Baude and G.J.M. Hagelaar, Appl. Phys. Lett. 104, 214107 (2014)
[2] G. Fubiani, L. Garrigues, G.J.M. Hagelaar, N. Kohen and J-P. Boeuf, New Journal of Physics 19, 015002 (2017)

Speaker: Freddy Gaboriau (LAPLACE, Université de Toulouse, CNRS)

6:20 PM PIC Simulation of Sheath Formation and Particle Loss Processes in Cusp Magnetic Fields for Negative Ion Sources

The multi-cusp magnetic field is widely used to improve plasma confinement in high-current negative ion sources for neutral beam injection (NBI) systems in fusion devices. Since confinement performance is affected by the plasma potential and magnetized sheath structure, understanding potential formation and particle loss processes in cusp magnetic fields is important. However, these mechanisms are not yet fully understood, especially in negative ion sources.
In this study, a two-dimensional Particle-in-Cell (PIC) simulation was carried out to investigate sheath formation and wall-loss distributions in a cusp magnetic field configuration. In simulations including positive ions and electrons, the sheath potential normalized by the plasma temperature increased as the plasma temperature increased. This trend is mainly attributed to the increase in the electron Larmor radius, which weakens electron confinement and increases electron loss to the wall. Characteristic wall-loss distributions caused by the cusp magnetic field structure were also observed. The effects of negative hydrogen ions on sheath formation and particle loss processes are also discussed.

Speaker: Mr Tetsunori Otsubo (Keio University)

6:40 PM Analysis of isotope effects on negative ion source extraction using 3D-PIC Calculation

In order to understand the physical mechanisms governing beam convergence, which is a critical issue in negative ion sources, numerical analyses of the extraction region considering surface-production have been conducted. Previous Particle-in-Cell (PIC) simulations have demonstrated that the relationship between surface-produced negative hydrogen ions and the potential structure affects the beam emitting surface and beam convergence. Nevertheless, under the deuterium operation required for future Neutral Beam Injection systems, isotope effects are expected to alter the interdependence among surface-produced negative deuterium ions, the potential structure, and beam convergence. In this study, the physics of beam extraction in deuterium negative ion sources are analyzed using a 3D-PIC code, and the impact of isotope effects on beam optics will be discussed in comparison with hydrogen cases.

Speaker: Katsuya Hayashi (核融合科学研究所)

6:40 PM Design of a High Current Beam Extraction and Transport System for the ISIS 2X Penning H- Ion Source

High current, long pulse H- beams are required for future accelerator applications, such as the Muon Collider or ESS Neutrino Super Beam where the ISIS 2X Penning ion source is a contender. The 2X source has demonstrated 75mA H- beam, 2ms pulse length, at 50Hz repetition rate on a dedicated test stand, and up to 150mA current at shorter pulse length. However, efficient transport of the beam from the source into the low energy beam transport (LEBT) and into an RFQ accelerator has yet to be developed. This work presents an IBSIMU-based simulation study and mechanical design of the 2X ion source beam extraction and transport focussing of a 140mA H- beam into the beamline of the Front End Test Stand (FETS) at ISIS. The extraction system design, based on two elliptical einzel lenses focussing the asymmetric beam, maintains compatibility with the existing ISIS 1X Penning ion source mechanical and beam parameters, allowing FETS to operate with either ion source.

Speaker: Dean Morris (STFC)

6:40 PM Direct comparison of extraction electrode current between experiments and PIC simulation in J-PARC RF-driven negative hydrogen ion source

Origin of negative hydrogen ($\text{H}^-$) ion beam parameter oscillation in J-PARC Radio Frequency (RF) -driven $\text{H}^-$ ion source is investigated by direct comparison between experiments and Particle-In-Cell (PIC) simulation. The bias voltage in the range from -100 to +100 V is applied between the extraction electrode (EE) and the plasma electrode (PE) under the RF plasma operation with 10 – 40 kW RF power input. The measured I-V curve of the EE with respect to the PE indicates the contribution of coextracted electrons under Cs-free condition. The PIC calculation model calculated numbers of electrons, positive ions, and $\text{H}^-$ ions reaching the EE crossing the plasma boundary formed near the PE as functions of time. The numerical simulation results of the EE current waveforms for corresponding experimental conditions are compared with the experimental results to validate the physical model employed for the simulation. Oscillation behaviors in trajectories of charged particles, equipotential surface distribution, and energy distributions visualized by the simulation model are examined for finding the factors influential upon determining the waveform of the EE current.

Speaker: Takanori Shibata (J-PARC/KEK/NIFS)

6:40 PM Experimental Studies on Negative Ion Production in a 13.56 MHz RF Ion Source

D-Pace is investigating the development of a 13.56 MHz RF-driven ion source for the production of negative ion beams. The ion source employs a hybrid design that combines features of the TRIUMF-licensed filament ion source and the RADIS ion source licensed from the University of Jyväskylä. The present work focuses on experimental studies aimed at improving the long-term beam current stability and overall operational performance of the RF ion source.

Experiments were conducted to evaluate the influence of plasma chamber surface materials and RF operating conditions on ion source performance. In particular, different plasma-facing materials were investigated to assess their effects on the extracted beam current stability. In parallel, a modified RF impedance-matching configuration was developed and tested to improve RF power coupling and reduce operational instabilities. Initial investigations of an internal RF antenna configuration were also carried out, and the first operational results are presented.

Speaker: Anand George (D-Pace)

6:40 PM Improvements to Plasma and Process Uniformity in a Plasma Immersion Ion Implantation (PIII) System via Multi-cusp Magnetic Confinement

Plasma Immersion Ion Implantation (PIII) is a high-fluence ion implantation technique well-suited for implanting large area and non-planar metallic and semiconducting targets [1-4]. The PIII system developed in the Bradley lab at the University of Saskatchewan (USask) is an ICP system in a bell-jar configuration [5] optimized for semiconductor and photonic device processing. One key advantage of PIII is its suitability for large-area targets- this is particularly relevant for semiconductor applications where large wafer size is important for high throughput. Therefore, ion implantation dose uniformity across a large target diameter is a key process parameter. Plasma uniformity in a large-diameter plasma chamber or ion source can be improved by multi-cusp magnetic confinement [6-8], as can the ion density for a given power, which is also important for high throughput in many applications. Motivated by this, recent improvements to the Bradley lab PIII Chamber include the addition of a multi-cusp magnetic confinement system. This poster will report on the technical aspects of this confinement, and consequent improvements to the plasma and process uniformity.

[1] M.P. Bradley, P.R. Desautels, D. Hunter, M. Risch, “Silicon electroluminescent device production via plasma ion implantation”, physica status solidi c, 6, S206-S209 (2009)
[2] M. Rishm M. Bradley, “Predicted depth profiles for nitrogen‐ion implantation into gallium arsenide” physica status solidi c 5 (4), 939-942 (2009).
[3] S. Qin, M.P. Bradley, P.L. Kellerman, K. Saadatmand, “Measurement and analysis of deposition-etch characteristics of plasma immersion ion implantation”, Review of Scientific Instruments 73 (2), 840-842 (2002).
[4] S.K. Purdy, A.P. Knights, M.P. Bradley, G.S. Chang, “Light-Emitting Diodes Fabricated From Carbon Ions Implanted Into p-Type Silicon”, IEEE Transactions on Electron Devices 62 (3), 914-918 (2015).
[5] J. Moreno, M. Jimenez, D. Okerstrom, M.P. Bradley, L. Couëdel, “Diagnostics of a Multicusp-Assisted Inductively-Coupled Radio-Frequency Plasma Source for Plasma Immersion Ion Implantation”, Open Plasma Science Vol. 2, No. 1 (2026).
[6] A. George, S. Melanson, D. Potkins, M. Dehnel, N. Broderick, H. McDonald, C. Philpott “Optimisation of D- Ion Production in a Production in a Multicusp Source”, Proceedings of IPAC2018 (2018).
[7] S.K. Hahto, S.T. Hahto, Q. Ji, K.N. Leung, S. Wilde, E.L. Foley, L.R. Grisham, F.M. Levinton, “Multicusp ion source with external rf antenna for production of protons”, Rev. Sci. Instrum. 75, 355–359 (2004)
[8] Yoshio Ueda, et al, “Effect of Substrate Potential on Plasma Parameters of Magnetic Multicusp Plasma Source”, Jpn. J. Appl. Phys. 37 3508 (1998).

Speaker: William Davis (Dept. of Physics & Engineering Physics, University of Saskatchewan)

6:40 PM Integrating a Laser Neutralizer Wire Scanner in the LANSCE H- LEBT

We present the results from a recently installed laser wire scanner for the H- beam at the Los Alamos Neutron Science Center (LANSCE) in the low energy beam transport (LEBT) section. The presented design is modular, supports orthogonal transverse input laser beam orientations, and acts as a test stand for implementing photodetachment measurements. A custom-built laser interaction point and drift chamber were added to the current beam line to photoionize the H- secondary electrons and collect the freed electrons in a custom-built, high-speed, Faraday cup detector. We have used this new apparatus to test H- neutralization efficiency as a function of laser intensity, in a laser-wire scanning configuration to characterize the transverse (x,y) H- beam profile exiting the LANSCE Cockcroft-Walton injector.

Speaker: Charles Rohde (Los Alamos National Laboratory)

6:40 PM Measurement of electron affinities at the HAMSTER facility

The Helmholtz Accelerator Mass Spectrometer Tracing Environmental Radionuclides (HAMSTER) facility [1] covers a wide range of applications from the environment to nuclear astrophysics.
For AMS, negative ions are extracted from a Rb or Cs sputter source and trace amounts of radionuclides are counted in a particle detector. A main limitation is the interference from stable isobars. Such interferences can be suppressed using the difference in electron affinities by laser-induced photodetachment. The Ion Linear Trap for Isobar Suppression (ILTIS) [2] decelerates a mass-filtered negative ion beam. Using He buffer gas, the residence time of the ions inside the ion cooler is increased to several milliseconds. A collinearly overlapped laser neutralizes negative ions at photon energies above the respective electron affinities or vertical detachment energies.
The setup also allows the determination of electron affinities.
We present results of the photodetachment of the BeF^- molecule using an OPO laser scanning over a range of wavelengths from 1110 nm to 1310 nm and recording the intensity of the surviving anions. The resulting electron affinity of BeF^- fully agrees with the literature value [3] and excited states of this molecule were observed. This technology is competitive to established techniques and opens applications of the HAMSTER for fundamental studies in atomic and molecular physics.

Speaker: Mr Laurenz Widermann (TU Dresden, HZDR)

6:40 PM Mitigation of Secondary Electron Trapping in Permanent-Magnet Ion Sources by Extraction Geometry Design

A permanent-magnet-based, microwave-driven helium ion source for the production of 1 mA positive beam and 20 µA negative beam via charge exchange is under development. Electron-trajectory simulations have been carried out to investigate a discharge phenomenon observed in the extraction system. The simulations revealed the formation of a charge trap caused by the topology of the permanent-magnet field near the extraction region. The trap leads to the accumulation of secondary electrons generated by beam collisions with the background gas. As a consequence, the extraction system becomes susceptible to electrical discharges between electrodes, limiting achievable beam transport and focusing performance.

Simulations performed with the ion optics library IBSimu indicate that the discharge issue can be mitigated either by replacing the conventional puller-einzel extraction configuration with a diode extraction geometry or by increasing the distance between the electrodes and the magnetic-field minimum. This work presents the magnetic-field structure responsible for the trap formation and discusses the relevance of the phenomenon for permanent-magnet-based ion sources generally.

Speaker: rebekka nagy (University of Jyväskylä)

6:40 PM Numerical Analysis of the Da Vinci project negative ion-based Neutral Beam Injectors

The planned Da Vinci Field-Reversed Configuration fusion reactor will require several Neutral Beam Injectors each delivering 1 MeV 5 MW continuous neutral beams. A considered design option includes a spatially separated H- ion source and an electrostatic accelerator as was previously proposed [1].
Here the status of the numerical analysis work supporting the ongoing design efforts is presented. The simulations include modeling and optimization of the H- ion source extraction system and the downstream transport, acceleration and neutralization systems with the goal of delivering the required beam at the reactor vessel beam injection port.
Special attention will be given to estimation of the required level of space-charge compensation together with the allowable stripping losses.
[1] A. Ivanov et al, Rev. Sci. Instrum. 85, 02B102 (2014) doi.org/10.1063/1.4826326

Speaker: Ken Franzen (TAE Technologies)

6:40 PM Optical emission spectroscopy for measuring electron temperature and density in a Penning ion-source test stand for the production of negative hydrogen ions

Optical emission spectroscopy for measuring electron temperature and density in a Penning ion-source test stand for the production of negative hydrogen ions

Authors
J. Doyle$^{1,2}$, G. Fubiani$^{3}$, C. Xiao$^{1}$, L. Couedel$^{1}$, M. Dehnel$^{1,2,3}$.

Affiliations

1. University of Saskatchewan — Department of Physics and Engineering Physics
2. Selkirk Ion-source Research Center (SIRC)
3. LAPLACE, Université de Toulouse, CNRS, Toulouse, France

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Abstract

A Penning ion-source test stand is being developed at the newly commissioned Selkirk Ion-source Research Centre (SIRC) in British Columbia, Canada. Two important species produced by this ion source are alpha particles and negative hydrogen ions, for use in medical cyclotrons [1,2] for radioimmunotherapy and positron emission tomography (PET). In a first experimental campaign, the Collisional-Radiative Model approach [3] will be used to map emission intensity ratios to population densities and temperatures of emitting excited states using optical emission spectroscopy (OES) in helium plasmas. A second experimental campaign will investigate H− ions, which are produced in our Penning experiments through two main mechanisms: dissociative attachment of thermal electrons to vibrationally excited hydrogen molecules, and, in a subset of experiments, surface interactions with cesium [4,5]. The efficiency of negative ion production is strongly limited by electron temperature; a 5 eV change can reduce the dissociative attachment rate by up to 10$^4$ [5]. Electron density and gas pressure are also critical control parameters, since H− ions are destroyed through collisions with positive ions, electrons, and hydrogen atoms. Plasma parameters are difficult to measure directly during standard Penning operation with a Langmuir probe. Instead, OES will be used as a non-invasive diagnostic tool to determine average plasma parameters (electron temperature and density) by comparing the relative intensities of specific spectral lines associated with rotational and vibrational transitions [6], combined with a machine-learning approach. The new test stand being developed at SIRC will include options for direct measurements, such as a Langmuir probe and Faraday cup, as well as a fibre-optic spectrometer to correlate spectral emissions with temperature, arc current, gas flow rate, and magnetic field. This poster will review the details of this theory and its consideration in the test-stand design, as well as the integration of the Langmuir probe and fibre spectrometer.

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References

1. Schmor, P. "Review of Cyclotrons for the Production of Radioactive Isotopes for Medical and Industrial Applications." Reviews of Accelerator Science and Technology 4, no. 1, 103–116 (2011).
2. Dehnel, M. et al. "H-, D- & He++ Source Developments for Medical Isotope Production Cyclotrons." 2024 International Topical Meeting on Nuclear Applications of Accelerators, Jefferson Lab, Norfolk, Virginia, USA, March 17–21, 2024.
3. Savard, N. "Development and Characterization of a Penning Ion Source Using Helium." PhD thesis, University of British Columbia, 2022.
4. Potkins, D. et al. "Improvements to Siemens Eclipse PET Cyclotron Penning Ion Source." AIP Conference Proceedings 2052, 050016 (2018).
5. Sereda, I., Hrechko, Y., Azarenkov, M. and Sereda, K. "Penning Source of Hydrogen Negative Ions Testing at Different Gases Injection and Optional Application of ZrV Cathodes." International Journal of Hydrogen Energy 109, 1321–1324 (2025).
6. Yang, Z. et al. "Studies on Hydrogen Plasma in a Penning Ion Source by Optical Emission Spectroscopy." IEEE Transactions on Plasma Science 41, 2941–2945 (2013).

Speaker: Jonathan Doyle (Selkirk Innovates)

6:40 PM Status of the internal RF antenna negative ion source for LAMP

The LANSCE Accelerator Modernization Project (LAMP) will replace the front-end of the existing LANSCE accelerator, from ion sources through the end of the 100-MeV drift-tube linac. LAMP requires higher peak H- beam currents, and longer lifetimes, than provided by the existing LANSCE H- ion sources. The project has constructed an SNS-style multicusp cesiated source with an internal RF antenna. This source operates in two modes: a 13.56MHz CW mode to ignite the plasma and a 2MHz mode which provides a high-power, pulsed plasma. In this paper, we discuss the commissioning status of the 2MHz plasma including the matching network, cage design, and deployed plasma diagnostics.

Speaker: Dr Madison Howard (Los Alamos National Laboratory)

6:40 PM Towards Ion-Beam Studies Using the USASK Dense Plasma Focus Device

The University of Saskatchewan Dense Plasma Focus (USASK-DPF) device is currently being optimized as a pulsed ion source for future plasma–wall interaction and material damage studies. USASK-DPF is a Mather-type dense plasma focus device consisting of a coaxial electrode arrangement enclosed in a low-pressure gas chamber and driven by the rapid discharge of a capacitor bank. During operation, the gas breaks down and forms a plasma current sheath that propagates along the electrodes before collapsing near the anode tip, forming a dense plasma capable of generating energetic ion beams, x-rays, and neutrons. Due to the relatively low operating cost and high ion fluxes, DPF devices are of interest for plasma–wall interaction studies. Previous studies have shown that damage factors due to DPF ion beams are similar to those associated with edge localized modes (ELMs) in modern tokamaks. Current efforts focus on implementing pre-ionization techniques, optimizing discharge conditions under different argon and hydrogen pressures, and developing ion-beam diagnostics. The main objective of this work is to improve discharge reproducibility and characterize the energy, flux, and fluence of the generated ion beams.

Speaker: Jeisson Vanegas (PhD student)

7:00 PM → 9:00 PM Hume: IAC Dinner/Mtg

Wed, September 23

7:45 AM → 8:00 AM Morning Coffee

8:00 AM → 8:10 AM Housekeeping

8:10 AM → 9:45 AM S1: Chairperson - Mark Roberts, WHOI

8:10 AM Review on alkali vapor charge exchange canals for He- and report on HIAF ANU alpha injector.

This paper reviews the operational principles, technical implementations, and fundamental physics of alkali vapor charge-exchange canals used for the production of negative helium (He⁻) ion beams. Emphasis is placed on performance characteristics, efficiency, and limitations relevant to modern accelerator applications. In addition, we report on recent upgrades to the Australian National University Heavy Ion Accelerator Facility (HIAF), specifically the enhancement of the alpha-particle injector. The upgrade includes the installation of an electrostatic analyzer and a new negative helium ion source, enabling reconfigured beam-line operation with up to three simultaneous ion sources. These improvements significantly enhance operational flexibility, safety, and injection performance, while expanding experimental capabilities in nuclear physics, space radiation testing, and advanced materials research.

Speaker: Nikolai Lobanov (Australian National University)

8:35 AM Negative Helium Ion Production Using Nano-Foils

Negative helium (He⁻) ion beams combined with tandem accelerators are used in research and industrial processes such as accelerator mass spectrometry and power semiconductor manufacture. The established production method involves double-charge exchange between a positive helium (He⁺) beam and a low-pressure metal vapour, typically an alkali. While this method achieves effective conversion rates of 1% to 5%, it introduces mechanical complexities and contamination issues. Specifically, maintaining the necessary low-pressure environment requires additional pumping capacity, and creation of the metal vapour typically requires an oven and system within the vacuum envelope to vaporize, condense, and recirculate the metal. Additionally, migrating alkali metal vapours can contaminate downstream processes. To address these equipment challenges, our research investigates the use of nanometer-thick solid foils (nano-foils) as an alternative charge-exchange medium.

In our previous studies, we utilized a helium ion microscope (HIM) equipped with a magnetic dipole and a CMOS radiation camera to measure charge uptake efficiencies [P.Jackle et al, 2026, "Production of negative helium ions via transmission through nano-foils", J. Phys. Conf. Ser. 3237 012061]. By transmitting a 30 keV He⁺ beam through various nano-foils, including carbon, gold, palladium, platinum, silicon dioxide, silicon nitride, and titanium oxide, we found that most materials yielded a relatively uniform He⁻ production ratio of approximately 0.02%, whereas we had anticipated substantially different production ratios.

Here we shall describe our experimental campaign aimed at a deeper understanding of the production ratio mechanisms. We discuss measurements of He⁻ production ratios using He⁺ energies of 35, 25, and 20 keV with all previously explored nano-foils. New measurements will also be presented with additional thicknesses of carbon nano-foils, increasing from single-layer graphene. By comparing these new thicknesses and varying beam energies against our established 30 keV baseline, we aim to provide deeper insight into surface versus bulk charge-exchange mechanisms and further evaluate the feasibility of nano-foils for He⁻ ion beam production.

Speaker: Philip Jackle (Simon Fraser University, D-Pace)

9:00 AM Microwave driven Permanent Magnet Negative Helium ion source

Negative helium ion sources are typically required for tandem accelerators where they are mostly used for materials analysis in the form of Rutherford backscattering spectrometry (RBS). As alkaline metal vapor is required for charge conversion of the positive ion beam to negative – with conversion rates < 2%, these type of He- ion sources tend to have limited beam intensity and maintenance lifetimes.

The work done in the Accelerator Laboratory of the University of Jyväskylä targets to develop a commercially available negative helium ion source where long life-time maintenance interval and up to 20 uA He- beam should be reached. This setup is based on the permanent magnet plasma chamber driven with the 2.45 GHz microwave RF-source from the ground potential. These design choices require only a small power consumption at the high voltage potential, enabling also a small footprint.

The extraction energy was originally targeted for the 5-7 keV, being optimal for the Rubidium based charge exchange, but it now seems obvious that to reach > 1mA positive beam, 10 or up to 15 keV extraction energies will be needed.

This presentation will go through the background, design and current status of the work as well as the existing problems of the permanent magnet design which causes issues in the extraction region.

Speaker: Mikko Laitinen (University of Jyväskylä)

9:20 AM Latest Developments of Liquid Spray Neutralization for Neutral Beam Injection

A large number of high-energy beams of negative ions and neutral atoms were observed when a beam of positive ions passed through a liquid spray. It has been shown that the energy conversion efficiency of positive ions into neutrals is 38% for 𝐻+→ 𝐻0 and 50% for 𝐶4+→ 𝐶0 [1] at energies up to 140 keV and 1.2 MeV, respectively. The method is rather general in nature and can be applied to other ion species, e.g., Deuterium and Oxygen negative ions and their neutrals were measured. This simple system, compared to gas neutralizers, can be an attractive option for neutral beam injection (NBI) systems.
The phenomena are ascribed to electron-capture and -loss by a high-energy positive ion in the spray. In a series of new experiments, positive and negative ions, as well as neutral particles, were spatially separated, and their spectra were quantitatively analyzed. However, comparison with the data available in the literature showed significant differences. The hypotheses, that the spray electrification may play a decisive role in these processes can only be qualitative unless confirmed experimentally.
It is clear that an improved model of electron transport must be developed to fully understand the mechanisms in collision system. Until such a model is available, the present experiments open a possibility for measuring the cross sections of electron capture and loss to benchmark future theoretical models.

Speaker: Prof. SARGIS TER-AVETISYAN (Extreme Light Infrastructure-Nuclear Physics (ELI-NP), IFIN HH, Magurele, Romania)

9:45 AM → 9:50 AM Industry 9: Cam Whitehead - LCCDTS: Industry

9:50 AM → 10:10 AM Coffee

10:10 AM → 12:10 PM S2: Chairperson - Jean-Baptiste Lallement, CERN

10:10 AM Lifetime and Emittance Optimization for High Intensity RF-driven H- Source

Lifetime and emittance are two key parameters for an RF-driven H$^-$ source used in high-power proton accelerators. At the China Spallation Neutron Source (CSNS), we have developed a high-intensity RF-driven H$^-$ ion source with an external antenna structure, capable of generating a beam current exceeding 60 mA. To extend the lifetime of the ion source, improvements have been made over the past several years to the plasma chamber structure, gas purification system, and cesium injection setup. Following these optimizations, a single plasma chamber has accumulated over 1,200 operation days, demonstrating nearly unlimited lifetime. To improve beam transmission through the radio-frequency quadrupole (RFQ), the emittance of the ion beam in the low-energy beam transport (LEBT) section has been minimized to 0.21 $\pi\cdot$mm$\cdot$mrad at a beam current of 60 mA. The study shows that not only the ion source parameters but also the solenoid configuration and space charge compensation play important roles in achieving emittance minimization.

Speaker: Weidong Chen (Institute of high energy physics, Chinese Academy of Sciences.)

10:35 AM Design choices, implementation and status of the PIP-II Warm Front End

The Proton Improvement Plan II (PIP-II) at Fermilab is a program of upgrades to the injection complex currently under construction. A major component is a new 2 mA, 800 MeV H- CW-compatible superconducting linac (a.k.a. Linac2), initially operating in a beam pulse mode. Installation of the Warm Front End (WFE) in the Linac2 facility is underway. Beam commissioning is planned to start in summer 2027.
The WFE consists of a 15 mA DC, 30 keV H- ion source, a 2 m-long Low Energy Beam Transport (LEBT), a 2.1 MeV CW Radio Frequency Quadrupole (RFQ), and a 13 m long Medium Energy Beam Transport (MEBT), which feeds the beam into the first cryomodule. In this paper, the WFE design is presented along with the rationale behind design choices. Among other Linac2 WFE peculiarities are the two identical sources in a Y-configuration, a partially un-neutralized transport scheme in the LEBT, and a long MEBT that includes a bunch-by-bunch chopping system. Details of their implementation and demonstration at the PIP-II Injector Test (PIP2IT) will be discussed as well as lessons learned. Finally, an up-to-date installation status will be given, highlighting some of the differences between the hardware used at PIP2IT and the final configuration eventually adopted.

Speaker: Lionel Prost (Fer)

11:00 AM Operational Experience with a Positive / Negative Filament Ion Source

A filament-driven ion source for hydrogen and helium ion beams, capable of producing both positive and negative ions, has been in operation at the Cyclotron Institute at Texas A&M University since early 2024. The ion source, manufactured by D-Pace, replaced an older filament ion source that only produced H- and D- ions. The +/- filament ion source has been installed on the vertical injection line of the K150 cyclotron. The cyclotron can accelerate either positive or negative ions according to polarity of its magnetic field. To date, the ion source has produced H- and He+ beams, accelerated by the cyclotron, for basic science, radioactive beam production, medical isotope production and radiation effects testing of electronics.
An overview of the ion source installation on the K150 cyclotron and its ongoing commissioning will be presented, along with a brief summary of the different applications of the beams that have been produced.

Speaker: Brian Roeder (Cyclotron Institute, Texas A&M University)

11:25 AM Current status of Proton and Neutron irradiation beamlines at the RFT-30 H⁻ Cyclotron Facility

The RFT-30 cyclotron facility provides a 30 MeV proton beam for radioisotope production and irradiation experiments using H⁻ ion acceleration with stripping extraction. The facility is being upgraded to expand its capability for proton and neutron irradiation studies.
The RFT-30 cyclotron employs a negative hydrogen ion source and a low-energy beam transport (LEBT) system for beam injection through an inflector into the cyclotron. Beam acceleration is achieved using a sector-focused magnet and RF cavity system designed to deliver high-energy proton beams.
The extracted beam is transported through a high-energy beam transport (HEBT) line consisting of four beamlines. Three of the beamlines are dedicated to radioisotope production, while one beamline is used for proton and neutron irradiation studies. The beam transport system includes steering magnets and quadrupole magnets for beam focusing and tuning, along with beam diagnostic components such as Faraday cups and collimators.
Based on this beam delivery capability, proton irradiation experiments are being conducted to support various research applications. In addition, a neutron irradiation beamline has been developed to expand the experimental capability of the facility.
The current status of the RFT-30 cyclotron facility and its irradiation beamlines is presented. Future developments will focus on improving beam transport performance and expanding irradiation capabilities, such as in-beam energy measurements using proton time-of-flight techniques and beam current monitoring using current transformers.

Speaker: Jongchul Lee (Korea Atomic Energy Research Institute)

11:45 AM Reliable long-life Operations and Record High beam current Demonstration of the H⁻ ion source at SNS

The ion source utilized in the SNS accelerator complex is an RF‑driven, multicusp‑confined, Cs‑enhanced H⁻ source. It is presently operated at approximately 50 mA of H⁻ beam current (measured at the LEBT exit) with a 6% duty-factor (1.0 ms, 60 Hz), supporting the SNS proton beam power on target near 2.0 MW. Producing this beam current typically requires about 50 kW of RF power for the ion source. Through enhanced hardware quality assurance and improved methods and protocols for refurbishment, conditioning, and operation, a single ion source installation can now reliably support an entire SNS run cycle (4–6 months) without the need for interruptive maintenance.

On the R&D front, a series of multifaceted enhancements to the beam extraction system have recently enabled the demonstration of H⁻ beam currents exceeding 150 mA at the same operating conditions of approximately 50 kW RF power and a 6% duty-factor. These advancements provide ample beam current margin for future SNS operations, including the planned two-target configuration with proton beam power up to 2.8 MW, and offer a promising pathway toward very high current, long‑lived H⁻ sources for next‑generation multi‑megawatt proton accelerators.

Speaker: Dr Baoxi Han (Oak Ridge National Laboratory)

12:10 PM → 12:15 PM Housekeeping

12:15 PM → 1:00 PM Lunch

1:00 PM → 6:50 PM Free Afternoon - Discover Nelson BC Canada

Thu, September 24

7:45 AM → 8:00 AM Coffee

8:00 AM → 8:10 AM Housekeeping

8:10 AM → 9:45 AM S1: Chairperson - Dirk Wunderlich, IPP-MPG

8:10 AM Negative Ion Source Developments at the ITER-NBTF in Padua towards the start of MITICA-HNB Operation

The ITER Neutral Beam Injection Heating and Current Drive system consists of 2 (upgradable to 3) Heating Neutral Beams (HNB) and 1 Diagnostic Neutral Beam (DNB).
A HNB system capable of these parameters had never been designed nor tested, hence the ITER Neutral Beam Test Facility (NBTF) was set up at Consorzio RFX premises (Italy) aimed at developing the injector prototype.
The facility includes two test beds: the full-scale HNB prototype, named MITICA, that will enter into operation in 2027, and SPIDER, with 100 keV particle energy, aimed at testing and optimizing in advance the ITER-size ion source, in operation since 2018.
This contribution describes the development progress at the NBTF in Padova related to ITER HNB-size beam sources deployed in SPIDER and MITICA, in particular highlighting the recent contributions of activities on both devices.
SPIDER completed the second campaign with good results, and is starting the third one, finally in full configuration to aim at the complete set of target parameters.
MITICA is progressing in the preparation for the start of operations. MITICA beam source was finally delivered onsite in June 2026, soon to be installed inside the vacuum vessel.

Speaker: Diego Marcuzzi (Consorzio RFX)

8:35 AM Stabilization of Long Beam Pulses at NNBI

The Neutral Beam Injection (NNBI) for ITER is based on large-scale RF plasma sources for negative hydrogen ions, which need to deliver high currents of H$^-$ and D$^-$ (up to 66 A) for up to one hour while maintaining the co-extracted current of electrons below the ion current. Cesium is used to enable the surface production of negative ions; however, the plasma-induced removal of Cs from the conversion surfaces leads to a steady decrease of the source performance during long pulses, particularly in deuterium operation.
The NNBI test facilities BATMAN Upgrade and ELISE (1/8 and 1/2 size of the ITER NBI source, respectively) contribute to the development program of the ITER NBI. Conditioning recipes and further measures (e.g. biased surfaces close to the extraction system) have been developed to stabilize and/or reduce the current of co-extracted electrons. These optimizations resulted in the reproducible achievement of almost 90% of the targeted extracted negative ion current (30 A) during 600 s hydrogen pulses at ELISE. Deuterium operation remains more challenging, since the co-extracted electron current increases much stronger during long pulses. An alternative Cs evaporation concept (“Cs shower”) has been tested at BATMAN Upgrade, allowing for direct control of the neutral Cs flux onto the converter surface during pulses. After further optimizations, 90% of the required scaled D$^-$ current was sustained for 1000 s for the very first time.
This contribution reports on these breakthroughs achieved at the NNBI ion sources towards long pulse operation and strategies to steady state operation are discussed. Results from plasma and beam diagnostics are presented.

Speaker: Christian Wimmer (Max-Planck-Institut für Plasmaphysik (IPP))

9:00 AM Experimental Investigation of Power Deposition Characteristics and Neutralization Efficiency in CRAFT NNBI Test Facility

Neutral beam injection (NBI) is one of the most important auxiliary heating and current drive methods for future fusion devices. In negative ion-based neutral beam injection (NNBI) systems, understanding beam power deposition and neutralization characteristics is essential for improving beam transmission efficiency and ensuring reliable long-pulse operation. In this work, a high-power neutral beam experiment is carried out in the CRAFT NNBI test facility to investigate the power deposition characteristics and neutralization efficiency under electrostatic deflection conditions. Thermocouple measurements, Water Flow Calorimetry (WFC) and Secondary Electron Detector (SED) are employed to measure the transient thermal response and beam power deposition on beamline components, including the neutralizer, electrostatic residual ion dump (ERID), and calorimeter. The relationships between beam transmission, residual ion power deposition, thermal loading distribution, and neutralization efficiency are systematically analyzed by varying the neutralizer pressure. The experimental results have been used to evaluate the operational stability and engineering reliability of the electrostatic deflection system. This work is expected to provide important experimental data and technical support for beam power deposition analysis, neutralization efficiency evaluation, and residual ion control in future high-power neutral beam injection systems for fusion applications.

Speaker: 旭峰 彭 (合肥综合性国家科学中心能源研究院)

9:20 AM Neutral Beam Injectors for ITER, Progress of Design and Manufacturing Activities

The ITER tokamak will rely on negative ion–based Neutral Beam Injectors (NBIs) for auxiliary heating and current drive, as well as for high resolution spectroscopic diagnostics of burning plasmas. The heating system comprises two, with an option for a third, Neutral Beam Injectors capable of delivering 16.5 MW of MeV class neutral hydrogen or deuterium atoms, while a dedicated Diagnostic Neutral Beam will operate at 100 keV to support advanced plasma measurements. Following the 2024 ITER re baseline, the development plan for these systems has been refined to align with the updated project schedule and integration strategy.
Manufacturing of the captive components is progressing, with installation of the injectors’ vessels, high voltage power supplies, and the magnetic field compensation system planned ahead of ITER’s first experimental phase and advancing with strong support from the Domestic Agencies. Full injector assembly and installation will follow the first operation phase, ensuring readiness for ITER’s nuclear campaigns. In parallel, design validation and performance optimization continue through dedicated modelling activities and within the long term experimental program at the Neutral Beam Test Facility, recently updated and aligned with ITER needs.
This contribution will present the current status of the ITER NBI program, highlight the technical progress achieved since the re baseline, and outline the remaining challenges and planned activities leading to injector deployment for ITER’s fusion operation campaigns.

Speaker: Carlo Poggi (ITER Organization)

9:45 AM → 10:10 AM Coffee

10:10 AM → 11:50 AM S2: Chairperson - Andrei Smolyakov, U. Sask

10:10 AM ExB Plasmas Generated by e-beams and non-thermal electrons for processing two-dimensional materials including negative ions and applications

There is a growing interest in the use of low temperature magnetized plasmas generated by electron beams and non-thermal electrons for processing of materials at atomic scale with applications to microelectronics and quantum systems.[1-3] For these applications, the plasma (density ~ 109-1010 cm-3 and electron temperature ~ 0.1-0.5 eV) is typically generated by injecting an energetic (102 – 104 eV) electrons into a low pressure (1-10’s mtorr) background gas along the applied magnetic field (~10-100 Gauss). The magnetic field helps to confine the plasma and separate the plasma regions with energetic electrons in the injected region and colder electrons at the plasma periphery. These partially ionized and partially magnetized plasmas can be subject to a number of instabilities including beam-plasma,[4] and gradient drift instabilities [5] which may, for example, alter the propagation of energetic electrons along the reactor and ion heating,[6] respectively. For soft processing applications, these effects may be unwanted as they can cause plasma non-uniformities and enhance ion-induced damage to substrates. In this talk, we will discuss results on mitigation of these instabilities and control of plasma kinetics using active boundaries.[7,8] A special attention will be devoted to applications of the ExB plasmas to processing of 2D materials such as graphene3, transition metal dichalcogenides (TMDs) as well as diamond.2 A potential role of negative ions generated in these plasmas will also be discussed.

References:
[1] D. R. Boris, S. C. Hernández, E. H. Lock, Tz. B. Petrova1, G. M. Petrov and R. F. Fernsler, ECS J. Solid State Sci. Technol. 4, N5033 (2015)
[2] C. Pederson, R. Giridharagopal, F. Zhao, S. T. Dunham, Y. Raitses, D. S. Ginger, K-M. Fu, Phys. Rev. Mater. 8, 036201 (2024)
[3] F. Zhao, Y. Raitses, X. Yang, A. Tan, and C. G. Tully, Carbon 117, 244 (2021)
[4] H. Sun, J. Chen, I. D. Kaganovich, A. Khrabrov, D. Sydorenko, Phys. Rev. Lett. 129, 125001 (2022)
[5] M. Tyushev, M. Papahn Zadeh, V. Sharma, M. Sengupta, Y. Raitses, J.-P. Boeuf, and A. Smolyakov, Phys. Plasmas 30, 033506 (2023)
[6] N. S. Chopra, I. Romadanov and Y. Raitses, Appl. Phys. Lett. 124, 064101 (2024)
[7] E. Rodriguez, V. Skoutnev, Y. Raitses, A. Powis, I. Kaganovich, and A. Smolyakov, Phys. Plasmas 26, 053503 (2019)
[8] N. S. Chopra, I. Romadanov, Y. Raitses, Appl. Phys. Lett. 33, 125003 (2024)

Speaker: Yevgeny Raitses (Princeton Plasma Physics Laboratory)

10:35 AM Charged particle transport in electronegative plasmas by particle-in-cell calculations

Electron and ion transport in non-equilibrium plasmas is inherently complex, exhibiting intricate behaviour in the phase space and in time. The Particle-In-Cell (PIC) method is widely used, being close to first principles and requiring few input parameters, enabling self-consistent simulations. Macroscopic particle transport is governed through collision phenomena and microscopic dynamics [1]. It is well established that satisfying the PIC numerical stability criteria, notably marginally resolving the Debye length, having sufficiently time steps to resolve the plasma frequency and satisfying the Courant condition, are mandatory for physical results. When transport is governed by electrostatic turbulence or strong instabilities, meeting these criteria at their margins proves insufficient. Particularly in the case of transport of electrons and negative ions in the vicinity of the plasma sheath and of an emitting surface, the transport of charged species is affected by the PIC code numerical parameters. Sub-Debye grid refinement combined with high-order shape functions is essential to capture physical effects and obtain accurate transport coefficients using the Green-Kubo formalism.

[1] Schiesko, L., Revel, A., Minea, T., & Carbone, E. (2022). On the use of ultra-high resolution PIC methods to unveil microscale effects of plasma kinetic instabilities: electron trapping and release by electrostatic tidal effect. Plasma Sources Science and Technology, 31(4), 04LT01.

Speaker: Emile Carbone (Institut National de la Recherche Scientifique - Centre Énergie Matériaux Télécommunications)

11:00 AM Implicit PIC Simulations of Negative Hydrogen Plasmas with Intense Negative Ion Production

High-density plasma discharges in hydrogen operating at low pressures are of considerable interest for negative ion production used in many applications. Their weak collisionality requires a kinetic, nonlocal description, and a popular approach is to model such discharges numerically using the particle-in-cell (PIC) method combined with Monte Carlo collisions (MCC). However, the most commonly used explicit variant of this method is highly inefficient because it must resolve both the Debye length and the plasma period. In this context, the energy-conserving implicit PIC/MCC scheme appears to be an attractive alternative, as it can model the plasmas of interest using their actual parameters without resorting to artificial scaling techniques.

This talk presents simulations of several types of high-density plasma discharges performed using electromagnetic or Darwin/electrostatic energy-conserving PIC/MCC codes in hydrogen, and discusses the observed negative ion production.

Speaker: Dr Denis Eremin (Ruhr University Bochum)

11:25 AM A Comparison of Implicit and Explicit PIC Schemes in One Dimension

Explicit particle-in-cell (PIC) codes are widely used to study the physics of plasma ion sources. However, in higher-dimensional simulations of high-density, low-temperature plasmas, computational cost becomes a major limitation due to the need to resolve the Debye length and plasma frequency timescales. Fully implicit, energy-and-charge-conserving PIC schemes offer the advantage of relaxing these spatial and temporal resolution requirements, as well as reducing the required number of particles per cell, thereby decreasing simulation runtime. However, relaxing these constraints can also affect simulation accuracy. This talk presents a review of comparative studies between explicit and implicit PIC methods in one dimension, focusing on how changes in spatial resolution and particles per cell impact the accuracy of implicit simulations, and what these tradeoffs imply for the practical use of implicit schemes in accelerating plasma simulations.

Speaker: Nicolas Savard

11:50 AM → 12:00 PM Housekeeping

12:00 PM → 1:30 PM Lunch

1:30 PM → 2:55 PM S3: Chairperson - Dan Faircloth, STFC UKRI

1:30 PM An Expanded Survey of H-/D- Injectors at National Laboratories: Ion sources, LEBTs and RFQs

Modern low-energy H-/D- injectors are used extensively in many large, accelerator-based, user facilities operating worldwide. Beams of these ions are used to fill circular accelerators and storage rings, to enable efficient extraction from cyclotrons and to double proton energy output from a tandem accelerator. The injector consists of an ion source, a Low Energy Beam Transport (LEBT) section and typically, a Radio frequency Quadrupole (RFQ) accelerator. Such facilities include the US Spallation Neutron Source (SNS), Japan Proton Accelerator Research Complex (J-PARC), Rutherford Appleton Laboratory (RAL-ISIS), Los Alamos Neutron Science Center (LANSCE), Fermi National Accelerator Laboratory (FNAL), Brookhaven National Laboratory (BNL), the CERN LHC injector, the Chinese Spallation Neutron Source (CSNS), Tri University Meson Facility (TRIUMF) as well as numerous installations of D-Pace deployed injector systems used mainly with cyclotrons delivering beams of deuterium. In addition, several future facilities and upgrades are being planned which will likely also utilize enhanced H- injectors. This report will first provide a simple description of these injectors, their operational parameters and discuss some of the associated R&D efforts. Specific attention will be paid to the RFQ component of the injector as it has not been covered in previous similar reviews [1]. A tabulation of each facility’s RFQ’s manufacturer, design and operating parameters, beam acceptance (Twiss parameters) and performance metrics will be provided.

[1] R. Welton, B. Han, O. Tarvainen and V. Morozov, “H- injectors for accelerators - status and prospects”, Journal of Physics: Conference Series 3237 (2026) 012053

Speaker: Robert Welton (ORNL-SNS)

1:55 PM Modeling of Beam Focusing with Radio Frequency Electric Field Perturbations

A critical issue in the development of radio frequency (RF) negative ion sources for ITER neutral beam injection (NBI) is the large beam divergence angle. One of the potential causes is the deformation of the beam extraction interface (meniscus) induced by the RF electric field. Previous work showed that the applied RF electric field near the meniscus triggered both oscillations and an increase in the beam divergence [1]. In this study, we developed a beam focusing model accounting for the RF electric field at the meniscus and compared it with previous experimental results. In this model, the RF electric field was introduced as a perturbation to the meniscus. The linear response of the model reproduced the experimentally observed oscillations of the beam divergence. The non-linear response (an increase in the divergence angle) was also reproduced by the time-averaging effect of the oscillations. It was confirmed that the linear and non-linear responses of beam focusing can consistently be explained by the model.

Speaker: Tsuyoshi Yasui (Nagoya University,Japan)

2:15 PM The DC voltage holding experiments in vacuum under cesium deposition condition

Abstract: Cesium injection is an effective and relatively mature method to improve the negative ion yield of negative ion sources. Cesium deposition on the component surface of negative ion based neutral beam injector (NNBI) accelerators is one of the key factors affecting insulation performance. At present, the correlation between cesium deposition amount and inter-electrode insulation level has not been fully investigated. This is one of the reasons why conservative cesium injection schemes or alternative methods for improving negative ion yield are adopted in the NNBI. The Institute of Plasma Physics, Chinese Academy of Sciences has recently conducted experimental research on DC voltage holding under cesium deposition in vacuum. The ultimate goal of this study is to establish the Paschen curve of negative ion accelerator electrodes under cesium deposition in hydrogen atmosphere. A vacuum chamber with a diameter of 1 m and height of 1.5 m serves as the main experimental facility for this research. A thermostatically controlled cesium crucible and a film thickness monitor were used for cesium evaporation and deposition thickness measurement, respectively. The experiments were first carried out without cesium injection to calibrate the electrode breakdown voltage under normal conditions. Subsequently, the system was evacuated to the ultimate vacuum achievable by the pump set, and the inter-electrode breakdown voltage was measured at different cesium deposition thicknesses. Then, the vacuum chamber was filled with hydrogen at various pressures, and the breakdown voltage was investigated under different gas pressures. Finally, the electrodes were heated to induce redistribution of the deposited cesium. Variations in cesium deposition thickness and the voltage holding performance during electrode heating were recorded.

Speaker: Dr Bo Liu (Institute of Plasma Physics, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, China)

2:35 PM Realta Fusion's Roadmap & Diagnostic Development

Realta Fusion is developing a tandem mirror machine, Hammir-DD, to achieve fusion-relevant temperatures using a high-powered negative-ion-based neutral beam injector (NNBI). We will experimentally verify this technology on a full-scale, single source test bed which is targeting a 200 keV beam with approximately 1 MW of neutral power for up to one second of operation.
In parallel, Realta is collaborating with the University of Wisconsin to study and optimize simple mirror performance on the Wisconsin HTS Axisymmetric Mirror (WHAM). WHAM, equipped with a 25 keV, 55 A positive-ion-based neutral beam injector (PNBI), also serves as a platform for developing ion source and beam diagnostics that will transfer to the single source test stand. This poster will outline Realta's roadmap and NBI diagnostic development on WHAM.

Speaker: Anthony Cooper (Realta Fusion)

2:55 PM → 3:15 PM Coffee

3:15 PM → 4:15 PM S4: Chairperson -Alexander Ivanov, TAE

3:15 PM Validation of the Formation of Negative Methane Ions.

We present the discovery and confirmation of a new negative molecular species, the CH$_4^−$ anion. The experimental realization of this high-spin exciplex was challenging because it overlaps at $m/q = -1$ with O$^-$, commonly present as a pollutant in vacuum systems. Electron detachment cross section (EDCS) showed diametrical differences with O$^-$ EDCS, this leaded to the hypotheses of negative methane which is not supposed to exist. Born–Oppenheimer molecular dynamics (BOMD) simulations finally revealed that this anion is a quartet ($S = 3/2$) metastable species, which leads to the formation of a molecular (CH$_2$ : H$_2$ )$^−$ excited complex.

Speaker: Guillermo G. Hinojosa Aguirre (Universidad Nacional Autonoma de Mexico)

3:35 PM Multi-Fidelity Simulation Approach for Negative-Ion Based NBI Development

Realta Fusion is developing fusion energy technology based on the magnetic mirror confinement concept, in which neutral beam injection (NBI) plays a critical role in plasma heating and fuelling. Designing a high-performance NBI system requires navigating a broad engineering and physics parameter space while ensuring that critical processes are accurately captured. To meet these complementary needs, a multi-fidelity simulation approach has been developed at Realta Fusion in which several computational tools operate at different levels of fidelity and serve distinct roles in the development process.

Initial scoping is done with RealBeam, a Python-based code developed in-house, which enables rapid and interactive exploration of a wide design space by simulating the beam envelope, neutralization and re-ionization reactions, magnetic deflection, power deposition, and beamline gas distribution. Promising configurations identified through RealBeam undergo kinetic-level validation with WarpX, an open-source particle-in-cell code, which is used to validate critical processes such as extraction, acceleration, neutralization, and space charge compensation, with results benchmarked against experimental NBI measurements from the WHAM device. Engineering realism is introduced through COMSOL, which performs self-consistent ion source plasma simulations and multiphysics analysis on representative CAD geometries, ensuring that physical predictions translate directly to the engineering design. This layered approach forms a cohesive framework that supports NBI development from early conceptual design through detailed engineering validation.

Speaker: Joey Eickman (Realta Fusion)

4:15 PM → 4:20 PM Housekeeping & ICIS2027 Announcement

6:15 PM → 7:00 PM Wine and Beer

7:00 PM → 9:00 PM Conference Dinner and Presentation of NIBS Award

Fri, September 25

8:15 AM → 9:00 AM Coffee

9:00 AM → 10:00 AM S1: Chairperson - Morgan Dehnel, SIRC

9:00 AM A Survey of Negative Ion Beam Applications

Negative ion beams are utilized over a wide range of application areas. This paper presents a review of a substantive number of utilization areas for negative ion beams as well as estimates of the number of negative ion beam systems installed, and the ongoing growth rate of each sector. Key application areas explored include national laboratory accelerators, national fusion centres, fusion start-ups, medical imaging, medical radio-immuno-therapy, Boron Neutron Capture Therapy (BNCT), ion implantation for semiconductor manufacture, Accelerator Mass Spectrometry, Carbon Dating, and several niche applications.

Speaker: Morgan Dehnel (SIRC)

10:00 AM → 10:15 AM Coffee

10:15 AM → 10:45 AM Conference Wrap-Up - NIBS2026 Chairperson: Dr. M. Dehnel

11:30 AM → 12:30 PM Lunch