Enhancement of the H[-] Output in the Magnetic Multicusp Ion Source

On optimization of the volume production type H^- ion source, the effect of wall material and wall temperature on H^- production, and the effect of plasma space potential V_s on H^- extraction in the multicusp ion source are investigated experimentally. When three different wall materials (i. e. Al, Mo and Stainless Steel) are used, Al generally produces the highest H^- current under the same discharge conditions. We think that the difference in H^- yield is due to different interactions of vibrationally excited hydrogen molecules with three wall materials. The wall temperature has no appreciable effect on the extracted H^- current. It is also found that decreasing V_s (>0) leads to an increase in the extracted H^- current.