DEVELOPMENT OF A 500 KEV, 22 A D- ION-SOURCE FOR THE NEUTRAL BEAM INJECTOR FOR JT-60U

The first results of the performance test of the large negative ion so urce for a JT-60U negative-ion-based neutral beam injector (N-NBI) are presented. The ion source consists of a cesium seeded multicusp plasm a generator, where negative ions are produced via volume and surface p rocesses, a 110 cmX45 cm multiaperture extractor, and a three-stage el ectrostatic accelerator. After negative ion production and voltage hol ding tests in test stands, the ion source was installed in the N-NBI s ystem and the full power test began. Up to now, the ion source has pro duced 400 keV, 5.9 A (2.4 MW) D- ion beams, the world highest D- curre nt and beam power, with a pulse duration of 0.1 s. (C) 1996 American I nstitute of Physics.