Spatial and temporal formation dynamics of glow discharge constriction and stratification

Abstract

In the present work, we experimentally study the formation dynamics of positive column constriction in neon glow discharge at intermediate pressures () with the simultaneous development of longitudinal instabilities in the form of moving striations. Discharge current, which exceeded the critical value for the transition to the constricted regime, was modulated by short rectangular pulses in order to avoid the inhomogeneous heating of the gas. During the pulse, the ionization balance was establishing and then discharge was switching to the constricted regime. The temperature field of neutral atoms was determined using interferometric methods based on a scheme of the Michelson interferometer. The heat equation was solved for the stationary and pulsed regimes. It is shown that under the described discharge conditions, in spite of the absence of inhomogeneous gas heating, discharge switches to the constricted regime with the appearance of moving striations. On the basis of the performed experiments, it can be concluded that inhomogeneous gas heating in neon is not the main cause of discharge constriction. A nonlinear dependence of the ionization rate on the electron density related to the Maxwellization of the electron energy distribution function should be considered as the basic mechanism of constriction.