We have recently reported [1] the production of cw proton beams from magnetically-confined microwave-driven sources, operating under non-resonant (non-ECR) conditions, with proton fractions greater than 0.95, the remaining fraction consisting of H_2~+ (0.05) with no H_3~+. We achieve this by the addition of H_2O to the plasma at molecular concentrations of ～1.0% and about 700 W 2.45 GHz RF power to the source. High-current (45 mA) high-power (45 kV) beams of >92% proton purity have been produced using this technique [2]. Additional impurity ions, O~+ at 4 parts per thousand (ppt) and OH~+ and H_2O~+ at 1ppt are produced. We report further progress using this technique and similar results we have achieved for cw D~+ beams with D_2O and H_2O additives. Finally, we report progress we have made in the direct extraction of cw H~- beams from microwave-driven sources in terms of ion source surface material and confining magnetic field configurations. Mechanisms are discussed.
展开▼
