Speaker
Description
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).
| Email address | lenaic.couedel@univ-amu.fr |
|---|---|
| Funding Agency | Agence Nationale de la Recherche |
| Visitor's Visa | no |
| Classification | Plasma and negative ion diagnostics |