Multiply-charged ion emission from a cyclotron-resonance-heated plasma ion source

Electron cyclotron resonance heated ion sources have become the prominent electron-stripping device used to produce multiply-charged ions. These ions are required for many applications ranging from atomic physics research to cyclotron injection. Unfortunately, many of these sources are designed, built and operated based on empirical knowledge acquired from past or existing machines. Much research remains to be performed before a solid understanding of the physical processes governing these sources can be gained. The work presented here attempts to partially bridge the gap between application and understanding. A time-of-flight spectrometer diagnostic system was implemented on MIMI to measure the endloss current density for specific charge states flowing from the mirror. The method of acquiring many spectra in a given shot over a relatively short span of real time, and averaging them to produce one averaged spectrum has proven quite effective in reducing random signal fluctuations. Also, shot-to-shot reproducibility becomes possible with this method -- a difficult and most welcome result. Ion cyclotron heating has been shown to increase ion temperatures tens of eV. The resonant species typically experiences the greatest temperature increase but transfers much of its energy to the remainder of the distribution via collisions. These temperature increases are consistent with those expected from antenna loading computations. Modeling of the important physical processes occurring in the plasma yields results consistent with those measured with the time-of-flight spectrometer. 62 refs., 68 figs., 9 tabs