Effect of the cathode surface temperature on the cathode fall layer parameters: experiment and simulation

Abstract

Combined experimental and numerical studies reveal a significant effect of the cathode temperature on the basic parameters (such as the electric field profile, thickness of the cathode fall layer, current density, and gas temperature) of the cathode fall of the self-sustained normal direct current atmospheric pressure glow discharge (APGD) in helium. Numerical models are spatially one- and two-dimensional and based on drift-diffusion theory of gas discharges. It was observed that heating of the cathode, resulting from a flow of the discharge current in APGD with a constricted positive column, leads to an increase of the interelectrode voltage if the cathode is not cooled and its temperature increases. With additional heating of the cathode by an external heat source, the interelectrode voltage tends to decrease. Radially inhomogeneous profiles of the reduced electric field on the uncooled cathode surface were measured. Simulation results exhibit reasonably good agreement with experiment for APGDs with cooled and uncooled cathodes.