Weakly ionized field-free plasmas enclosed in emitting surfaces

Abstract

Calculations are presented for the spatial charge-density distribution in a stationary, weakly ionized, low-pressure plasma which is enclosed in plasma-emitting surfaces. Solutions are given for the cases that the emitting boundaries are two infinite parallel planes, an infinite cylinder, a sphere, and a cylinder of finite length with absorbing end faces. The theoretical results for the finite cylinder are compared with experimental data on helium, argon, and nitrogen at pressures between 0.1 and 0.5 Torr using a new plasma source. The plasma is produced by a discharge in a region between two concentric cylinders; the inner one, the anode, is perforated and a quiescent diffusion-plasma free of electric fields and electric currents is formed in its interior with densities between 108 and 1011 cm−3 and electron temperatures of 0.3 to 0.5 eV. Qualitative agreement between the observed and calculated density distributions has been found in certain cases.