Role of the secondary electron emission avalanche in surface flashover or insulators in vacuum

Abstract

As is well known, an insulator in vacuum subjected to high-voltage stress may experience rapid electrical breakdown via surface flashover. Although electron multiplication on the insulator surface is generally thought to play an important role in the flashover mechanism, a full understanding of this role is lacking. <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1–6</sup> In this work, the low-impedance discharge is assumed to occur in a layer of plasma generated by the electron avalanche, rather than in a thin layer of adsorbed gas on the insulator surface. <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3,5,7</sup> Heating by the avalanche is considered as a mechanism by which gas is evolved from the insulator surface.