Speaker
Description
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.
| Email address | julian.hoersch@ipp.mpg.de |
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| Visitor's Visa | no |
| Classification | Plasma and negative ion diagnostics |