Progress on simulating the initiation of vacuum insulator flashover

Vacuum insulators are critical components in many pulsed power systems. The insulators separate the vacuum and non-vacuum regions, often under great stress due to high electric fields. The insulators will often flashover at the dielectric vacuum interface for electric field values much lower than for the bulk breakdown through the material. Better predictive models and computational tools are needed to enable insulator designs in a timely and inexpensive manner for advanced pulsed power systems. In this article we will discuss physics models that have been implemented in a PIC code to better understand the initiation of flashover. The PIC code VORPAL has been ran on the Linux cluster Hera at LLNL. Some of the important physics modules that have been implemented to this point will be discussed for simple angled insulators. These physics modules include field distortion due to the dielectric, field emission, secondary electron emission, insulator charging, and the effects of magnetic fields. In the future we will incorporate physics modules to investigate the effects of photoemission, electron stimulated desorption, and gas ionization. This work will lead to an improved understanding of flashover initiation and better computational tools for advanced insulator design.