Review of developments on polymers' breakdown characteristics and mechanisms on a nanosecond time scale

Abstract

The breakdown of polymer insulators at a nanosecond scale is a serious problem for high-voltage devices and pulsed power systems. This paper reviews recent developments in research on the mechanisms and characteristics of the breakdown of polymers at a nanosecond scale at the Northwest Institute of Nuclear Technology. An improved avalanche breakdown model is proposed, and a formula for the strength of the electric breakdown (EBD) is formulated based on it. The formative time lag of the avalanche breakdown model is then developed to verify it. Two research groups were formed to study the characteristics of the breakdown. One focused on the characteristics of single-pulse breakdown, such as the effects of size, polymer type, electrode, pulse width, and pulse polarity on EBD, with the aim of deriving expressions for EBD. The other research group examined cumulative (multi-pulse) characteristics of the breakdown with the aim of deriving a formula for the lifetime of the polymer. A method to design solid insulation structures is finally proposed.