Nanosecond pulse generation with nonlinear capacitors and magnetic power compression

Abstract

Summary form only given. High voltage nanosecond range repetitive pulse generators to generate pulsed corona streamer discharges for environmental applications are now being widely explored. Conventionally, pulse generators for these applications have been designed using high voltage transformers and magnetic power compression systems. But this equipment lacks adequate enough energy transfer efficiency and also it is bulky. Recently some researchers have tried to use the voltage amplification effect of nonlinear ceramic capacitors to make very fast high voltage generators. The capacitance of these nonlinear capacitors changes by one order (one tenth) after passing a definite amount of charge. This results in voltage amplification. Two different of topologies were investigated using nonlinear capacitors DE120F103Z2K, manufactured by Murata Co. Its capacitance is rated at 10nF with a voltage rating of 2kV. They can withstand about 5/spl sim/6 kV for short period of time. To use the capacitors for the generation of high voltage pulse, it is necessary to connect them in series. However operating them in series can create some problems, due to the wide spread variations in their parameters in the nonlinear operating range. That is, the changes are not simultaneous and their capacitance values are not identical. Uneven voltage across the series capacitance can cause electrical breakdown before the required voltage is reached. Equalizing the voltage with resistors will cause substantial decrease of energy transfer and, hence, results in low system efficiency. We have reached a pulse voltage of 60kV for a load of 500 with a pulse width of 110nS (FWHM) for one compression stage. With two stage compressions we have obtained 80kV with a pulse width of 80nS (FWHM) for the same load.