Theoretical and experimental investigations on the process of high-pressure discharge development

The voltage breakdown behavior of a plane-parallel gap of 0.48-mm length filled with helium was examined at atmospheric pressure with admixtures of dry air at relative pressures of 0, 10^-4, 3×10^-4, and 10^-3. The initial stages of the breakdown were investigated by means of a quantitative model consisting of the electron, ion, and excited-particle conservation equations and the Poisson equation. The system of equations was solved for an applied voltage of 180 V, at one single partial pressure of the impurities. Two numerical routines were used for the solution: a commercial IMSL subroutine TWODEPEP, and a newly developed method of solution in several fractional steps. The results were compared and found to be in reasonable agreement although the new method indicated a somewhat slower rate of rise, particularly concerning electron density. The new method permits extension of the calculation up to electron densities equal to almost two orders of magnitude above the earlier limit