Theoretical Investigation of a UV Laser Triggered Spark Gap

A model of a spark gap used as a shorting switch in a Blumlein pulsed power system has been developed. The spark gap is a gas-filled switch that is triggered by an ultraviolet laser pulse. Methods of reducing the rate at which the resistance of the arc falls are the focus of this investigation. The model consists of two separate parts: a kinetic model, which shows the formation of the plasma streamer, and a fluid model, which describes the behavior of the arc after the connection is made. The kinetic model results represent the initial conditions of the arc described by the fluid model. Increases in the initial radius of the arc resulted in lower resistance for the first 10 ns after the connection is made, while changes in conductivity showed a consistent reduction of the current throughout the life of the arc. Reorienting the laser trigger spot yielded the most significant increase in the initial radius of the streamer, 25%.