| Popis: |
Measurements of the H/sup +/, H/sub 2sup +/, and H/sub 3sup +/ fractions and emittances of a hydrogen beam extracted from an RF-driven multi-cusp source were made using a bending magnet and an electrostatic emittance scanner. The H/sup +/ fraction increased with RF power. Fractions in excess of 90% were obtained. At a given RF power, the H/sup +/ fraction increased with decreasing source pressure and increasing filter rod separation. When the "collar" surrounding the extraction aperture (used for H/sup -/ operation) was removed, the H/sup +/ current increased by a factor of /spl ap/4, without changing the H/sup +/ fraction at a given RF power. With a large filter rod separation, H/sup +/ currents on the order of 100 mA were achieved at /spl ap/20 kW of RF power. Using a modified extractor operating at 35 kV, H/sup +/ currents on the order of 60 mA were obtained with a 90% normalized rms emittance of 0.012 /spl pi/cm-mrad. > |
