Global model for flashover phenomena in vacuum: A comprehensive perspective

Abstract

Flashover is an electrical breakdown along the dielectric-gas/vacuum/liquid interface under high electric field excitation. Surface flashover phenomena in vacuum greatly impede a variety of vacuum insulation devices and systems. Here, a comprehensive perspective of the vacuum flashover global model is provided to integrate existing understandings and highlight featured prospects of the flashover mechanisms, mitigation approaches, and applications. An overview of physical processes involved in the entire vacuum flashover process is first given. Recent advances and perspectives for the understanding of these processes are then discussed separately, including the surface discharge above dielectric, and the charge transport and breakdown within dielectric bulk and surface layer. Scaling laws and empirical formulas for flashover threshold prediction are assessed as well. The mechanisms of recent vacuum flashover mitigation approaches are analyzed, such as using physical structures and geometrical modifications, material-based approaches, and applying external electromagnetic field, and possible novel flashover mitigation methods are predicted. In addition, potential applications using vacuum flashover are discussed. Finally, promising research topics, imminent challenges, and open questions of the vacuum flashover studies are presented. It might be instructive for the fundamental and application research studies of surface flashover in vacuum in future.