High-current, high-duty-factor experiments with the H ion source for the Spallation Neutron Source

The ion source for the 1 MW Spallation Neutron Source (SNS) is required to provide 35 mA of H^- beam current at 6% duty factor (1 ms pulses at 60 Hz) with a normalized rms emittance less than 0.15 π mm mrad. The H^- beam will be accelerated to 65 keV and matched into a 2.5 MeV RFQ. The ion source is expected to ultimately produce 70 mA of H^- at 6% duty factor when the SNS is upgraded to 2 MW of power. For this application, a radio-frequency driven, magnetically filtered multicusp source is being developed at Berkeley Lab. The design of this new ion source is directed towards operation at the required high duty factor. Experimental results of the ion source operated in pure volume production mode (without cesium) and in hybrid mode (with cesium released into the source) are compared. An improved cesium dispensing system is presented