Effect of Foil Edge Modifications and Configurational Changes on Energy Storage Capacitor Weight

Corona failure at foil edges is the principal failure mechanism in well-designed and manufactured high energy-density pulse-discharge capacitors. By forming the foil edge with laser cutting or spark discharge machining, a 25-percent increase in corona inception voltage (CIV) over untreated edges is obtained. Folded foil produces a larger increase. Weight minimization using peak edge field as the limiting factor suggests that a configuration where the foil and dielectric are of equal thickness produces the lightest capacitor. Typical designs are presented.