Performance investigations on gap switch through pulsed triggering

Summary form only given: The transient behavior of gap switch during its short closing stage, particularly, dynamical resistances R_s(t) based on the Rompe and Weitzel (R&W) model for various spark gap configurations, has been studied through numerical simulations. A large scale FORTRAN code SPARKGAP has been strenuously implemented in previous works, but preliminary assumptions were made that the physical processes and associated numerical algorithms implemented were strictly valid for static discharging or triggering conditions under uniform fields. While the field enhancement factors (FEF) applied to estimate breakdown voltages were fixed constants, the model is physically zero-dimension, thus, quite approximated even for simple uniform geometric configurations of two-electrodes (no trigger-pin). In this paper the primary objective is to upgrade the code, first, by considering FEF changing with distorted fields, particularly due to sharp trigger electrode by means of static charge simulation method (CMS). CMS is incorporated, both in space and time, at each time step of outer iterations in the code. Quasi-two- or simplified one-dimensional space-time field effects imposed by trigger-pin applied pulses are tackled. Second, space-charge effect on ionization waves (IW) of streamers is evaluated for breakdown initiation with critical field and electron avalanche length. Henceforth, electron swarm parameters, like reduced ionization and attachment coefficients, are further updated during pulsed triggering. Third, the competing processes of bridging subgaps across main electrodes and to trigger pin are evaluated with streamer velocities and IW propagation. Fourth, peculiar phenomena of overvoltage triggering are barely explored for avalanche issue of locality evolving to global characteristics. In addition to main gap spacing, gas pressures, medium mixtures, special treatments on triggering schemes of subgap spacing, trigger pulse shapes and discharging polarities relative to anode and cathode are implemented. Furthermore, the temporal gap inductances correlated with the channel expansions of plasma columns are iterated in the physics modeling while intrinsic sub-gap capacitances are fixed. Phenomenal simulations with aforementioned improvements are extracted for parametric comparisons, thus, predictions for possible enhancements of switch performance are deduced to optimize the gap designs and triggering schemes.