Quasi-steady-state multimegawatt ion source for neutral beam injection

Abstract

A quasi-steady-state (pulse duration of 30 s) ion source of the duoPIGatron type has been developed for fusion applications. It was designed to deliver an 80-keV hydrogen ion beam of low beamlet divergence (Θrms= 0.26°) at a current density of 0.19 A cm−2. Hydrogen ion beams of 40 to 48 A were extracted at beam energies of 77 to 80 keV for 30-s-long pulses. The reliability and stability of the ion source operation were demonstrated by extracting about 600 beam pulses at full power and full pulse length. The ion source was also operated with deuterium as the working gas, and the optimum current at 80 keV was found to be about 33 A, in agreement with the expected inverse square-root scaling of current density with atomic mass.