Surface Flashover

In this talk we will introduce surface flashover phenomena and some recent results. Surface flashover occurs when a plasma discharge forms above/along an insulator material surface between a cathodic and anodic surface. Unlike the simpler case of gas discharge between two electrodes (i.e., a Paschen or Townsend discharge), in surface flashover the surface couples to the plasma in critical ways. The different mechanisms involved in the coupling include electron-induced secondary electron emission (i.e., multipactor breakdown), ion-induced secondary electron emission, and photon-induced secondary electron emission (photoemission). In addition, the surface itself can charge according to net incoming/outgoing charge transfer, resulting in changes to the surface electric field. Finally, the presence or absence of a pre-existing gas can drastically change the behavior of surface flashover. In a vacuum insulator flashover system, the breakdown gas material (fuel) must be liberated from the surface or electrodes.