A high-repetition rate closing switch for EMP applications

Summary form only given. The closing switch is one of the most important components in any compact pulsed power system intended for applications requiring a high repetition rate, and it plays an important role in determining the characteristics of the system. Without any gas flow, commercial high-power sparkgap switches have a voltage recovery time of about 10 ms, normally limiting their repetition rate to 100 Hz. As a result of various recent developments, switch operation has however become possible at very much higher frequencies.The present paper outlines the development of a high repetition rate EMP generator based around a 0.5 MV Tesla transformer. The spark-gap closing switch required in the primary circuit utilises a novel application of the corona stabilisation that is achieved when one of the electrodes is highly stressed and produces a non-uniform electric field. In an ambient electronegative gas, such as SF6, the space-charge cloud that forms around the electrode reduces the local electric field strength and voltage recovery is achieved without any pre-fire. The paper will outline the switch design and present experimental results for the EMP generator operating at a repetition rate in excess of 1 kHz.