Repetitive pulse application of self-healing high voltage capacitors

Abstract

In the last fifteen years, self-healing high voltage capacitors have become standard technology for single-shot and low repetition rate (<1 shot/minute) applications in R&D environments, such as inertial confinement fusion, electromagnetic launchers, electrochemical guns, high field magnet facilities, etc. Such capacitors offer higher energy density and/or longer life and higher reliability in many applications. Standard self-healing capacitors, built with vapor-deposited metallized electrodes, have limited ability to carry both peak pulse and continuous RMS (root mean square) currents, generate more heat than discrete foil capacitors, and have lower thermal conductivity for heat dissipation. For these reasons, many pulse power applications have been unable to utilize self-healing technology. For example, moderate to high repetition rate (/spl ges/10 Hz), high voltage capacitors built today are generally not of the self-healing type due to the higher energy losses and poorer thermal conductivity of metallized electrode capacitors. This results in large thermal gradients and overheating. Instead, such capacitors are still manufactured using discrete foil electrodes, which provide excellent electrical and thermal conductivity. The economic and technical benefits of self-healing capacitors continue to drive research and development to expand their operational envelope. Areas of research include "hybrid" electrode systems, integrated cooling, segmented electrodes, and higher temperature dielectrics. This paper will explore the application of self-healing capacitor technologies to repetitive pulse power systems. Present status of the technology will be described and future performance improvements will be projected.