Parametric study of the vacuum ultraviolet emission and electrical characteristics of a He-Xe microdischarge

Vacuum ultraviolet emission and electrical characteristics of a simple disc harge configuration consisting of two planar cylindrical electrodes operate d with a dc voltage have been measured over a wide range of He/Xe mixtures and discharge pressures. Breakdown characteristics are consistent with thos e found in the literature, however current-voltage characteristics and the inferred discharge resistivity suggest the presence of a complex process co ntrolling electron emission at the cathode. Ultraviolet vacuum emission map s of atomic and molecular xenon at 147, 150, and 173 nm, respectively, have been measured as a function of pressure, from 60 to 500 Torr, and gas mixt ure, from pure Xe to 5% Xe in He. The calibrated ratios of each emission ma p help to visualize the zones of strongest ultraviolet emission over a wide range of operating conditions. One-dimensional simulations of the breakdow n voltage and current discharge have been performed using the commercially available discharge-modeling package SIGLO. Good agreement with experimenta l results is found in the case of pure helium and xenon, however, in the ca se of pure xenon, the gas temperature was adjusted (elevated) in order to r eproduce the measured current-voltage characteristics. Modeling of the elec tron number density distribution indicates that the discharge is principall y composed of a thick ion sheath near the cathode. (C) 2001 American Instit ute of Physics.