Modeling Gap Closure Within Vaporizing Transmission Lines of Pulsed Power Machines Using Particle-in-Cell Direct Simulation Monte Carlo (PIC-DSMC)

Abstract We use a hybrid PIC-DSMC approach for modeling gap closure and examine the effectiveness of the novel variable weight DSMC method Event Splitting for this problem. Event Splitting has been shown to decrease computational costs and simulation noise in 0-D and 1-D electrical breakdown simulations by modeling all collision outcomes with the probability of each event reflected in post-collision macroparticle weights. Gap closure occurs in high-energy vacuum diodes where vaporized diode material creates a quasineutral plasma capable of disrupting the current. We examine the framework of our reduced surrogate simulation for reaching a fully closed gap and provide a discussion of the physics present during wave propagation across the domain as the quasineutral plasma evolves. Our results show that due to a lack of a more robust merging scheme, event splitting provides little benefit for the gap closure simulations considered in the present work.