High-intensity H− ion source with steady-state plasma injection

Abstract

To satisfy the requirements of a negative-ion-based neutral beam line for future fusion applications, an H− ion source was developed using surface production of negative ions and a steady-state plasma injection from hollow cathode discharges. Steady-state and stable generation of H− ions on a negatively biased, cesiated converter has been achieved over periods of several hours; H− beam current pulses of 0.3-A amplitude with 1-s duration have been extracted over the same period, but steady-state operation of the extractor has not been achieved yet due to a lack of extractor cooling. The source meets some of the neutral beam line requirements, i.e., the obtained linear current density, background gas pressure, and the proven capability for steady-state H− ion generation.