Separation of vacuum and gas breakdown processes in argon and their influence on electrical breakdown time delay

Abstract

Research presented in this paper is dealing with the determination of static breakdown voltage Us in an argon-filled tube at 0.5 mbar pressure, for different inter-electrode gaps d with the aim of separating vacuum and gas breakdown processes contribution in electrical breakdown time delay. The Us determination was performed using data on the dynamic breakdown voltage experimental data obtained for different voltage increase rates. It was shown that up to d≈9 mm estimated value of Us is relatively small change corresponds to breakdown which is vacuum-like, where as for d > 9 mm, breakdown takes place as in normal gas discharge. For d≈1 1 mm, Us has the minimal value, when gas ionization process induced by secondary electron emission from the cathode is maximal. The measurement of electrical breakdown time delay td was performed for three different values of inter-electrode gap: 0.1, 4 and 11 mm. On the basis of memory curve (mean value of electrical breakdown time delay t‾d as a function of relaxation time) behavior and statistical analysis of td data, mechanisms which make main impact to breakdown initiation were estimated for different values τ. Also, the impact of additional electron yield originating from UV radiation with wavelengths 302, 312.5 and 313.1 nm on the memory curve were investigated.