Theoretical Investigation of a UV Laser Triggered Spark Gap

Abstract

beginning and end of the life cycle of the arc in the laser triggered gas switch. A model of a spark gap used as a shorting switch in a Blumlein pulsed power system has been developed. The II. MODELS spark gap is a gas-filled switch that is triggered by an ultraviolet laser pulse. Methods of reducing the rate at A. Kinetic Model which the resistance of the arc falls are the focus of thisThe simulation space of the spark gap had a rectangular investigation. The model consists of two separate parts: a shape, 0.6 mm high and 0.3 mm wide. The size was kinetic model, which shows the formation of the plasma chosen to be the smallest possible to encompass the entire streamer, and a fluid model, which describes the behavior width of the streamer, but large enough that few electrons of the arc after the connection is made. The kinetic model escape the sides of the simulation. The simulation space results represent the initial conditions of the arc described was divided into square grids roughly half the Debye by the fluid model. Increases in the initial radius of the length, around 0.5 ptm. The grid dimensions were arc resulted in lower resistance for the first 10 ns after the 512x1028. This allowed for plasma with XD > 1 Ztm to be connection is made, while changes in conductivity simulated stably. The top boundary of the simulation showed a consistent reduction of the current throughout space represented the high potential electrode and was the life of the arc. Reorienting the laser trigger spot modeled as an equipotential boundary with a DC bias of yielded the most significant increase in the initial radius 1800 V or 2400 V. The bottom boundary, which of the streamer, 25%.represented the low potential electrode, was modeled as a grounded conductor. These two boundaries established a I. INTRODUCTION linear electric field of 3 MV/m or 4 MV/m, respectively.The side boundaries were modeled as a dielectric with a relative permittivity of one to simulate a gas dielectric.Blumleins are well known compact pulsed power ty , sources [1]. A Blumlein is two transmission lines stacked Argon or Neon at room temperature filled the simulation together with the center plate charged to a high voltage space at a pressure of 1 atm. These conditions represent and the load connected between the low potential plates. the intrinsic switch characteristics and were varied to When one of the transmission lines is shorted by a switch, determine the effect on the streamer radius and the a high voltage pulse appears across the load. This effect streamer conductivity at the end of the simulation time.a high voltage pulse appears across the load. This effect Inzto a eeae ntesic ouea is cumulative; several Blumleins stacked will produce Ionzation was enerated in the switch volume at a several times the original voltage [2-3]. One possible fixed rate. This rate can either represent the small amount shorting switch for the transmission lines in a Blumlein is of aioi taturallocrring in the switc space a laser triggered, gas-filled spark gap [4]. A spark g...

Research on the Time-Delay Characteristics of the Laser-Triggered Vacuum Switch

“…where n 0 is the neutral gas density, σ s is the cross section of the gas, and kT e is the electron temperature of the plasma [14]. Structure Fig.…”