A DIRECT-CURRENT PENNING SURFACE-PLASMA SOURCE

After developing a pulsed 8X source for H- beams, we are now testing a cooled, dc version. The design dc power density on the cathode surfac e is 900 W/cm2, much higher than achieved in any previously reported P enning surface-plasma source. The source is designed to accommodate dc arc power levels up to 30 kW by cooling the electrode surfaces with p ressurized, hot water. After striking the arc using a 600-V pulser, a 350-V dc power supply is switched in to sustain the 100-V discharge. N ow our tests are concentrating on arc pulse lengths less-than-or-equal -to 1 s. Ultimately, the discharge will be operated dc. The source is described and the initial arc test results are presented.