Design considerations for corona-stabilized repetitive switches

Abstract

Self-closing corona-stabilized switches have been developed to operate at pulse repetition frequencies (PRFs) which extend well into the kilohertz regime. The performance of these devices illustrates that corona-stabilized plasma closing switches are an effective alternative to conventional uniform or quasi-uniform field switches which utilize gas-flow techniques, high gas pressures or both to achieve high-PRF operation. Corona stabilization takes place in electronegative gases such as air and and requires the presence of a highly divergent electrical field. Under dc, or slowly rising charging voltage conditions, a space charge develops around the highly stressed electrode which prevents premature breakdown and allows full voltage recovery to take place. This means that PRFs extending into the kilohertz regime can readily be achieved. Self-firing corona-stabilized switches have been demonstrated to provide PRFs of up to 5 kHz and triggered corona switches have been shown to be capable of operation at 10 kHz. The lifetime of corona-stabilized switches has been demonstrated to approach about shots. The paper describes the design of a corona-stabilized switch, including detailed electrostatic field analysis of the electrode geometry. This analysis was undertaken to establish the effect of the electrode geometry on the field distribution within the switch. The switch design was flexible and allowed a study of the effect of certain parameters on the switching performance. These parameters include the gap spacing, the gas pressure and the profile of the electrodes. The switch was operated under single-shot conditions to establish the breakdown voltage against pressure (V-p) characteristics and in a continuous repetitive mode to assess the PRF operation. The results show that the best repetitive performance is produced using electrodes which generate a high field over a region sufficient to generate a stabilizing corona.