Numerical simulation of atmospheric-pressure helium DC glow discharge considering gas dynamics*

In DC glow discharge at atmospheric pressure, a local temperature rise occurs due to Joule heating. The change in temperature field also causes a local gas density change, which is an important factor because it affects the shape of the DC glow discharge. In this work, we developed a numerical model coupling the gas dynamics and the plasma in a nozzle-to-plane He glow discharge. The gas dynamics was obtained by solving the continuity equations for compressible fluids, and the plasma was calculated by coupling the continuity equations for charged species with Poisson's equation. The plasma and gas dynamics were numerically analyzed independently, and the coupling was achieved by repeating the calculations three times to reflect important parameters such as momentum, heat, gas density and temperature. The gas was a mixture of 99.9% He and 0.1% N₂. DC +350 V was applied to the nozzle anode, and the grounded cathode was a metal plate with 300K.  As a result, circulatory convection flow based on the heat and ion induced force was observed. It indicated the effect of heat convection. As the interaction analysis was repeated, the gas temperature near the cathode center increased from 300K to 462K.