Short-Pulse Operation With The Sitex Negative-Ion Source

The successful high current, long‐pulse SITEX source experiments with H− beams have been extended to D− operation and to short‐pulse H− and D− beam acceleration. Extracted D− beam current densities of 100 mA/cm2 at the plasma grid have been achieved for 3 s at a total beam of 260 mA and 10 keV. The extracted electron‐to‐D− ratio is <5% with ≊100% of the extracted electrons collected at 2 keV. Short‐pulse beams down to 10 ms in length have been accelerated with the minimum pulse length determined by the power supply time constants. Optics of the accelerated beam is θ(1/e)⊥=±0.48°, which corresponds to a normalized emittance perpendicular to the slot of 0.0007π cm‐mrad. These data place an upper limit on the surface conversion D− ion temperature of 0.7 eV.