Improving efficiency of negative ion production in ion source with saddle antenna.

Extraction of negative ions from a saddle antenna radio-frequency surface plasma source is considered. Several versions of new plasma generators with different antennas and magnetic field configurations were tested in the small Oak Ridge National Laboratory Spallation Neutron Source Test Stand. The efficiency of positive ion generation in plasma has been improved to 200 mA/cm² kW from 2.5 mA/cm² kW. A small oven was developed for cesiation by cesium compounds and alloy decomposition. After cesiation, a current of negative ions to the collector was increased from 1 mA to 10 mA with 1.5 kW RF power in the plasma and longitudinal magnetic field B₁ ~ 250 G. The specific efficiency of H^- production was increased to 20 mA/cm² kW from 2.5 mA/cm² kW. [ABSTRACT FROM AUTHOR]