Abstract
An experimental investigation of a stacked plasma generator of MAECKER type has been performed at low pressures (25-760Torr) and low electric currents (10-60A) for argon gas. Radial distributions of electron density and electron temperature were obtained by measuring the intensities of spectral lines and continuum from cylindrically confined plasmas. Based on such data of the macroscopic plasma parameters, the SAHA equilibrium relation, and the collisional and radiative theory of BATES et al., the spatial extent of equilibrium region and nonequilibrium effects of electronic excitation of the atom have been examined. In the plasmas generated in the apparatus, electron temperature ranged from 7, 500 to 11, 000°K and electron density 7×1014 to 3×1016cm-3. It was found that thermochemical equilibrium conditions existed only in the vicinity of the tube axis even at relatively high pressures and high currents, and the higher excited levels than the 5p level of argon atom were always in SAHA equilibrium with free electrons.
