Numerical simulation of atmospheric pressure dc glow discharge along a miniature helium flow in nitrogen

We carried out two-dimensional numerical simulation of atmospheric pressure dc glow discharge between nozzle and plate electrodes. Since helium is injected from the nozzle into atmospheric pressure nitrogen, the discharge is generated along the helium flow. That is, the spatial distribution of helium is very important for determining the discharge property. The purpose of this work is to clarify the relationship between the glow discharge property and helium mole fraction distribution. We found that the discharge is generated in the region with helium mole fraction larger than 99 %. The dominant ionization process is direct ionization of He in the cathode fall region and Penning ionization of N2 in the cathode fall region and along the side surface of positive column. The polarity of applied voltage also influences the discharge structure.