A Realistic Spark-Gap Model in Computer Simulation of Blumlein Transmission Line

Over the years, the use of numerical simulations in the development of high voltage pulse generators has become a standard approach. Nevertheless, the modeling of spark-gaps, one of the most commonly used switching devices in such generators, has always been a weak point of the process, especially in coupled circuit and field simulations. Although the complex SPICE spark-gap models do exist, it is difficult or impossible to directly couple them with field simulations. Thus, in many cases, the spark-gap models used were elementary and required many assumptions, which led to the prolongation of the design process. Our paper describes the coupling of a realistic circuit model of an air spark-gap, with a Finite Element Method simulation, solving the wave equation in the time domain. The simulation describes the operation of a Blumlein transmission line as a pulse generator. One of the advantages of the proposed solution is that the input parameters of the empirical model are measurable physical quantities characterizing the spark-gap circuit. We have carried out two numerical experiments testing the simulation for both the matched, resistive load and for a dipole antenna connected to the output of the Blumlein transmission line. The test results confirm that the circuit-field simulation can model Blumlein transmission lines with both simple elements (e.g., resistors) and complex circuits (e.g., an equivalent circuit of a dipole antenna) attached to its terminals.