High-Voltage Spark Gap in a Regime of Subnanosecond Switching

Abstract

This paper describes an investigation of a highvoltage 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.Index Terms-High-pressure spark discharge, subnanosecond discharge, subnanosecond high-voltage generators.

Investigation of the switching characteristics of high-pressure subnanosecond gas dischargers with the purpose of a sharp increasing of the breakdown voltages and the switching speed

“…The second important parameter of any spark gap is the pulse breakdown voltage (U br ). In general in the subnanosecond range [22][23][24][25][26][27][28][29] and as observed in the experiments [27][28][29] analyzed in this study, breakdown occurs at the front of the voltage pulse applied to the gas discharge gap (figure 1). Obviously, a number of technological and research tasks may require dischargers with the highest possible U br .…”

“…The entire array of data obtained during the processing of oscillograms on t d was analyzed by using an avalanchestreamer model [30,31,33]. This analysis is widely used in the study of the breakdown delay time in pulsed gas discharges [23][24][25][26]66]. The model assumes the development of an EA from the initiating electron, which, gaining the critical number of carriers (N cr ), transforms into an ionization wave (IW) directed to the anode (streamer).…”

“…At higher pressures, the electrical breakdown of the gap will occur before we reach the value E cr /p required by the runaway criterion, since E cr increases proportionally to p [30,47]. Therefore, when analyzing the prebreakdown stage at gas pressures above 3 atm, the avalanche-streamer model of the discharge development was usually used [23][24][25][26]66].…”

Sustainable Non‐Thermal Plasma‐Assisted Nitrogen Fixation—Synergistic Catalysis

“…Furthermore, to studyt he PNOi nteractions, the effects of the plasma discharge parameters (voltage,c urrent, etc.) must be taken into account.K orolev et al [46] investigated the influence of the discharge currento nt he formation of NO using a glow-type plasma. This study identified the importance of cur- Table 1.…”

“…ChemSusChem 2019, 12,3702 -3712 www.chemsuschem.org rent in the NTPNF process and provided an approximation on the energy requirement to form one molecule of NO under plasma conditions, which was 50-35 eV. [46] Hao et al investigated the effects of air flow rate, applied power,a nd geometric parameters using ap lasma jet nitrogen fixation processes. [47] On the other hand, Namihara et al focusedo nt he effect of temperatures on NO x synthesis.…”