Effect of gas heating on development of an independent high-pressure glow discharge in inert gases

Abstract

In high-pressure gas discharge systems Joulean heating of the gas changes integral properties of the discharge such as current density and cathode voltage drop. In the cathode dark space (cds) of an independent glow discharge the electric field intensity is several orders of magnitude higher than in the positive column, so that by discharging to atoms fast ions heat the gas mainly in a thin layer adjacent to the cathode. In gas discharge tubes the nonuniform energy contribution over the discharge gap produces a longitudinal motion of the gas and formation of shock waves, the intensity of which determines the rate of energy introduction. In the low-field range the gas heats weakly, since the ion temperature is close to the gas temperature and transfer of energy from electrons to atoms is hindered by the great difference in their masses. An analytical treatment of perturbations in a laser medium was performed in [I] in the acoustic approximation. The interferograms obtained in [2] clearly show shockwave propagation from the cathode through the active laser medium. Gas heating was also estimated from the measured velocity of wave propagation. A dependent glow discharge was described in [3] by numerical solution of the gasdynamic equations in the steady-state case and in the isobaric approximation. The present study will carry out a self-consistent calculation of the nonsteady-state system of gasdynamic equations for a thermally conductive gas and the equations describing a gas discharge in the drift approximation. Evolution of a glow discharge in neon, heating of the gas, shock-wave formation and propagation, and changes in cathode voltage U C and discharge current j are traced.