Computational study of current-voltage characteristics of a dc atmospheric pressure glow discharge using a 3D model*

Atmospheric pressure glow discharges (APGDs), due to their versatility and high degree of thermal nonequilibrium, are used in diverse applications, e.g. industrial, environmental, medical. AGPDs have been reported to exist in a self-sustained operation for currents ranging from ~ 100 microamps to 10 amps. At high current operation, instabilities leading to glow-to-arc transition are commonly observed; yet, self-sustained operation can be achieved by careful cooling of the electrode and gas. Computational APGD models are often derived from models for low pressure glow discharges, which often neglect advective gas transport. A 3D computational model of APGD in helium, including thermal and chemical nonequilibrium, and advective gas transport, is presented. The plasma is composed of e^-, He, He^*, He⁺, He₂^* and He₂⁺ species. The set of model equations is solved in a monolithic approach using an in-house-developed Finite Element Method solver. The model is applied to the simulation of a pin-to-plate APGD in helium over a large range of current. The results are shown to be in agreement with experimental results reported in the literature.