Plasma diagnostics by laser spectroscopic electric field measurement*
U. Czarnetzki1, D. Luggenhölscher1, V. A. Kadetov1, and H. F. Döbele2
1Institute for Plasma and Atomic Physics, Ruhr-University Bochum, 44780 Bochum, Germany; 2Institute for Experimental Physics, University Duisburg-Essen, 45117 Essen, Germany
Abstract: Laser spectroscopic electric field measurements have the potential to become a versatile tool for the diagnostics of low-temperature plasmas. From the spatially and temporally resolved field distribution in the sheath close to electrodes or surfaces in general, a broad range of important plasma parameters can be inferred directly: electron temperature; ion density distribution; displacement-, ion-, electron-diffusion current density; and the sheath potential. Indirectly, the electron and ion energy distribution functions and information on the ion dynamics in the sheath can also be obtained. Finally, measurements in the quasi-neutral bulk can also reveal even the plasma density distribution with high spatial and temporal resolution. The basic concepts for analysis of the field data are introduced and demonstrated by examples in hydrogen discharges.
Keywords: plasma diagnostics; plasma sheaths; RF discharges; microwave discharges; laser spectroscopy; electrical field measurement.
*Paper based on a presentation at the 16th International Symposium on Plasma Chemistry (ISPC-16), Taormina, Italy, 22-27 June 2003. Other presentations are published in this issue, pp. 345-495.