High speed gas breakdown in plasma closing switches

High-speed, plasma closing switches are capable of exhibiting rapid (sub-nanosecond) voltage collapse over a range of voltages and pressures. This property makes them useful in topics of current interest such as laser drivers and ultra-wide band radar equipment. In order to optimise switch behaviour for a particular application, knowledge of how the operating parameters of the switch affect the breakdown process is required. The experimental investigations described in this paper were performed with the gas pressure being varied between 0.15 and 3 bar absolute. For these investigations a constant electric field was maintained, prior to breakdown occurring. The gases tested were sulphur hexafluoride, helium, hydrogen and nitrogen. The results showed that sub-nanosecond voltage collapse times were achieved in these gases within this pressure range. The fastest voltage collapse was obtained in sulphur hexafluoride at a pressure of 0.15 bar.