Recent progress on high power negative ion sources at JAERI

Abstract

Abstract R & D's on high power negative ion source at JAERI are reviewed. A method of cesium injection into volume source has drastically progressed in development of the high current source. The H− ion current was enhanced up to 10 A only by seeding cesium of a few hundreds mg into a volume production type magnetically filtered multicusp source. Reductions of the optimum gas pressure and the electron current were also observed in the operation of cesium seeded sources. These effects are helpful in stable ac-celeration of the ion beams. High energy negative ion beam acceleration was demonstrated in the cesium seeded sources. So far, we have succeeded to accelerate 0.13 A H− ion beam up to 350 keV for 1 s with good beam optics of the divergence ωl/e ∼ 5 mrad. Two methods of the beam focussing were attempted; i.e. aperture displacement and curved grids extraction. The beam focussing by aperture displacement was found to be useful for the high power beam steering, while the beam merge experiment were being p...