Development of a 100eV, high-flux ion beam acceleration system

A new system of electrodes has been developed for a high-flux, steady-state ion source with a large irradiation area to study plasma-wall interaction in fusion reactors at energies in the 100eV range. These electrodes are multiaperture triode electrodes—the sizes of which are smaller as compared with those used in similar applications for previous systems. In particular, these electrodes have a thickness of 0.5mm and an aperture size of 0.9mm in diameter with 0.5mm gaps between them. The influence of the plasma sheath on the beam energy has to be estimated since the plasma sheath potential is comparable to the acceleration voltage in such a low energy region. Source plasma is produced by a hydrogen arc discharge, following which hydrogen ions are extracted by using the new electrode system. Ion fluxes of 1.5×1020–5.3×1020H∕m2s with energies ranging from 28to102eV∕H were obtained. These values are comparable to those of conventional high-flux ion sources with higher energies. This low energy ion beam can b...