Energy Anomalies Observed in Ion Beams Produced by rf Sources

Abstract

The beam characteristics of several Thonemann rf sources have been studied as a function of source parameters such as oscillator power, magnetic field, gas pressure, and extraction potential. Beam energy spreads 10 to 100 times thermal, and mean beam energies 100 to 400 eV above the extraction potential are consistently observed. The maximum beam intensity appears to be independent of mass from M=4 to M=40. A qualitative explanation of the energy effects is discussed.