The initial stage of the breakdown of discharge gap “point-plane” filled with nitrogen and SF6 at elevated pressure
D.V. Beloplotov1,2, M.I. Lomaev1, D.A. Sorokin1, V.F. Tarasenko1,2
1Institute of High Current Electronics (IHCE) of Siberian Branch of the Russian Academy of Sciences, 2/3, Akademichesky Avenue, Tomsk, 634055, Russia
2National Research Tomsk State University, 36, Lenin Avenue, Tomsk, 634050, Russia
Keywords: sulfur hexafluoride, nitrogen, non-uniform electric field, elevated pressure, ionization wave
Abstract
The initial stage of the breakdown of sulfur hexafluoride (SF6) and nitrogen in the non-uniform electric field at high pressures was investigated. High voltage pulses with amplitude of up to 350 kV were applied across the discharge gap with "point-plane" geometry of the electrodes. The experimental results on the dynamics of the light emission from the different zones of the discharge gap can be explained by formation of the ionization wave started from the potential electrode with a small radius of curvature. It was found that the speed of ionization wave front in nitrogen and SF6 is higher in the second half of the discharge gap as compared to the first one. At increasing SF6 and nitrogen pressure the speed of ionization wave front was shown to decrease. At negative polarity of high voltage pulse the average speed of ionization wave front was shown to be of ~ 2 cm/ns in SF6 at a pressure of 0.25 MPa and ~ 3.6 cm/ns in nitrogen at a pressure of 0.3 MPa.
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