Pulsed Cs beam development for the BNL polarized H- source

A pulsed Cs+ beam has been developed for use on a polarized H- source. Cesium ion production is by surface ionization using a porous tungsten ionizer. While satisfactory current pulses (5 to 10 mA greater than or equal to 0.5 ms) can be obtained, the pulse shapes are a sensitive function of the ionizer temperature and Cs surface coverage. The beam optical requirements are stringent, and the optics have been studied experimentally for both Cs+ and Cs0 beams. Computer calculations are in good agreement with the observed results. The present source has delivered 2.6 mA of Cs+ through the interaction region of the polarized ion source, and as much as 2.0 particle mA of Cs0. A new source is being built which is designed to give 15 mA through the interaction region