Scaling Parameters for Optically Triggered Hollow Cathode Switches Obtained by Computer Simulation

Abstract

Low pressure plasma switches are essential components of pulse power devices. A new class of high current electrically isolatable switches, the optically triggered pseudo-spark, is currently being developed for applications where conventional thyratrons are inadequate. The analysis and computational design of these switches is complicated by the fact that the electron energy distribution in low pressure pulsed power plasma devices is typically not in equilibrium with the local electric field. A new computer model has been developed to describe electron transport for these conditions and it has been applied to the optically triggered pseudo-spark, or Back-Lit-Thyratron (BLT). The model uses two groups of electrons described as the “bulk” and the “beam”. The energy distribution of the bulk electrons is nearly in equilibrium with the local electric field while the beam represents those electrons whose energy is equal to the local electric potential and which have not undergone collisions after being emitted from the cathode. The model is used to investigate the commutation phase of switching in the BLT.