Long pulse characteristics of 5 MW ion source for SST-1 neutral beam injector

We present characteristics of a 5 MW ion source for SST-1 neutral beam injector. Before the source could be tested for its performance, it was conditioned by 480 arc discharges of Is and beam extraction of hydrogen species at various beam voltages ranging between 19 kV and 56 W. Breakdown free beam extraction could be secured only after about 3000 beam second extraction. The ion source is capable of delivering 1.7 MW of neutral beam power at 55 kV with horizontal and vertical focal length of 5.4 m and 7 m respectively. Beam divergence is similar to 0.97 degrees. Steady-state beam energy of 31 MJ at 41 W was achieved during 14 s long beam extraction. We have not noticed any deterioration of beam parameters, including beam divergence during long pulse operation. These results indicate that 0.5 MW of neutral beam power at 30 W required for heating of plasma in SST-1 can be delivered. (C) 2008 Elsevier B.V. All rights reserved.