Ion Beam Probe Measurements of Electron Temperature

Abstract

The technique for measuring electron temperature with an ion beam probe has been refined, the time resolution reduced and the limitations evaluated. The technique involves sequentially probing the same volume of plasma with beams of different ion species and using the observed secondary ion currents and the known ionizing cross sections to evaluate the electron temperature. Spatial resolution is less than 0.1 cm3 and the time required to obtain a radial temperature profile is presently 10 msec. Detailed measurements have been made on a hollow cathode discharge and the results compared with Langmuir probe and spectroscopic data. Quantitative results can only be obtained with K+ -Na+ beams due to the lack of cross sections for other ion species. Better experimental data has been obtained with Rb+ and Cs+ beams but they cannot be reduced to Tee Theoretical cross sections provide qualitative indications of the system behavior but are not sufficiently accurate to permit quantitative data reduction.