Application of microdischarges to a spark gap operation in a regime of high pulse repetition rate

Abstract

Summary form only given. It is known fact that discharges in spark gaps at high pressure > 10 atm, which are capable of fast switching (less than 1 ns), are widely used for high power pulse generator. In such spark gaps, typical inter electrode distance is larger than several millimeters. We investigated discharges in short inter electrode distances on the order of 100 Icircfrac14m. The reason for employing discharges in short electrode gaps or micro discharges is to decrease the switching time even with a pressure close to 1 atm and subsequently obtain a sub nanosecond current rise time. Beside that, the deionization time of micro discharges decreases, which forms the prerequisite for the spark gap operation with a very high pulse repetition rate. It is obvious that for these conditions we do not concentrate on the discharge operation of the spark gap in a high current or extremely high voltage mode (high energy mode), but to concentrate on achievable high repetition rate at a low energy operating mode1. A miniaturized spark gap is built in a coaxial type geometry of 50 Icirccopy impedance. The current pulse propagates over a transmitting line to a matched load. A prerequisite for the design and development of the spark gap system is to operate it by dc voltage stress without any external triggering. In addition, we focused on a free voltage recovery process, i.e., without any external cooling or gas flow technique. Several parameters for this purpose such as the electrode gap distance, electrode geometry, gas type, gas pressure, and including the charging scheme with applied voltage and current ratings are investigated, which in one or other way dependent on each other. In parallel, a commercial Spice simulation program has been executed to establish the experimental investigation.