Circuit Analysis of a Gas Flow Switch

The circuit analysis of a gas flow switch is presented. The objective of the analysis is to model the switching process during spark gap breakdown. This information is useful in understanding switch operation and identifying ways to improve switch performance. A lumped circuit model is used to describe a gas flow switch during the switching process. Certain circuit element values are determined experimentally through static tests. Other component values, including a time-varying switch resistance and inductance, are estimated from current measurements. In particular, unknown constants in expressions for gap resistance and inductance are determined using an iterative parameter estimation technique. Distortion of the measured data due to frequency limitations of the measuring probe is corrected using a discrete inverse filtering method. The effects of random measurement error on the model element estimates are characterized in an error bound analysis. A description of the spark gap circuit model, parameter estimation technique, inverse filtering procedure, and error bound analysis are presented. Simulated switch current data, including the effects of probe distortion and measurement error, are generated in order to illustrate and verify the modeling procedure. The procedure is then applied to the gas flow switch under development in the Pulsed Power Laboratory at Old Dominion University. Results of this study, including estimated gap resistance and inductance, are presented.