High brightness rf ion source for accelerator-based microprobe facilities

The article discusses possible ways of increasing beam brightness in radio frequency (rf) ion sources. The characteristics of rf ion sources with different permanent magnet systems are investigated. Experiments were performed with argon and helium gases. A beam brightness of ∼100 A/(m2 rad2 eV) was attained at a plasma density of 3×1011 cm−3 for argon and 1×1011 cm−3 for helium. The ion current density inside an emission hole with 0.6 mm diameter of was 10 mA/cm2 for rf power input into the plasma of 40 W (frf=27.12 MHz). Measurements of the current value and emittance were performed with an ion source test facility permitting measurements of the current, emittance, ion beam mass composition, and rf power input into the plasma.