Development of a compact nanosecond pulse generator

Recently, pulsed power technology has been used in various field such as high density energy, industrial, medical, food, and agricultural applications. Non-thermal plasma generation is the key research for those applications. There are many papers report that the shorter duration and faster rise time, fall time of input voltage enables the higher energy efficiency in plasma processing. Therefore, development of a pulse generator with extremely short pulse duration is needed. Nanosecond pulse generator that developed at Kumamoto University can generate high voltage with rise time and fall time of 2 ns each, and the pulse width of 5 ns. This nanosecond pulse discharge has better results in ozone generation and NO treatment than other non-thermal plasma methods. The reason is because nanosecond pulse discharge mainly consists of streamer discharge phase so that the heat loss caused by glow discharge phase is small. Therefore, the nanosecond pulse discharge system including a nanosecond pulse generator and a reactor is known as a highly energy efficient method for plasma processing. However, Miniaturization of the nanosecond pulse discharge system is needed. The nanosecond pulse generator consists of a microsecond pulse generation circuit and a nanosecond pulse forming line. Currently, the devices are relatively large and the volume of the total system is 91.3 L. In this research, the miniaturization of both microsecond pulse generation circuit and the nanosecond pulse forming circuit were developed aimed for miniaturization with keeping its output characteristics. The IES pulse generation circuit employing an IGBT was designed as the microsecond generation part, and the high voltage coaxial cables were designed as the nanosecond generation part. The total volume was successfully reduced to 12.1 L.