High-Voltage Spark Gap in a Regime of Subnanosecond Switching

This paper describes an investigation of a high-voltage spark gap in the conditions of subnanosecond switching. The high-voltage pulsed generator “Sinus” is used to charge a coaxial line loaded to a high-pressure spark gap. Typical charging time for the coaxial line is in a range from 1 to 2 ns, maximum charging voltage is up to 250 kV, and a range of pressures for the gap is from 2 to 9 MPa. The theoretical models of the switching process on subnanosecond time scale are examined. A general equation for temporal behavior of the gap voltage, which is applicable for the avalanche model and the Rompe-Weitzel model has been obtained. It is revealed that the approach based on the avalanche model offers a possibility to describe the switching process only at extremely high overvoltages. The Rompe-Weitzel model demonstrates a good agreement with the experimental data both for the conditions of static breakdown and for the regime of a high overvolted gap. Comparison of experimental and calculated voltage waveforms has made it possible to estimate an empirical constant in the Rompe-Weitzel model (the price of ionization). This constant is varied from 420 to 920 eV, depending on the initial electric field in the gap.