Experimental Study and Numerical Simulation of Breakdown of a Gap with a Sharply Inhomogeneous Electric Field Distribution

The results of an experimental study of breakdown of a cone-to-plane gap, filled with nitrogen at a pressure of 12.5-400 kPa at a negative polarity, and its numerical simulation by the XOOPIC code are presented. The formation of a diffuse discharge is observed within the entire range of pressures. At the nitrogen pressures of up 200 kPa, a large-diameter streamer is formed in the gap. At higher pressure, two streamers of smaller diameters are observed to form. At low nitrogen pressures, the streamer starts forming at a certain distance from the cathode. The numerical simulation demonstrates that under these conditions the electrons rapidly leave the near-cathode region due to the high reduced electric field strength. The excitation of nitrogen molecules is taken into account in the simulation. Using the R-391/394 ratio of the emission intensities from the bands of the N-2(+) molecular ion and the N-2 molecule, the dynamics of the electron temperature T-e and the reduced electric field strength E/p in the plasma are determined. The streamer velocity is determined from the propagation velocity of the R-391/394 maximum along the gap. The results are compared with the numerical simulation results.

Automated summary

The experimental study of breakdown of a cone-to-plane gap filled with nitrogen at different pressures, along with numerical simulation, reveals the characteristics of streamer discharge at various nitrogen pressures, as well as the dynamics of electron temperature and electric field strength.