NONLINEAR EXPANSION OF THE CATHODE REGION IN ATMOSPHERIC-PRESSURE GLOW-DISCHARGE

The results of numerical simulation of the cathode region (CR) formation in atmospheric pressure glow discharge in nitrogen are presented. The effect of nonlinear motion of the CR/plasma boundary towards the anode was found. This effect is caused by creation of a two-layer CR structure: an ionization layer near the cathode surface and an ionization-free layer of space charge adjacent to the CR/plasma boundary. Evolution of ion density within the ionization-free layer forces the CR/plasma boundary to move away from the cathode. It is shown that the velocity of CR expansion is proportional to 1/square-root t. In the light of this effect the difference between high- and low-pressure glows is discussed.