In creating  electric discharges, plasma, or extreme environments, instantaneous high voltage or high current is necessary. Pulse power supply is a technology capable of generating an enormous MW, GW order amount of electrical power instantaneously.

Until recently, this technology has only been used in special research fields.  Currently this technology is used in the industry and in consumer products. In this time, the important points are 1)  Long life time 2) High repetition 3) High efficiency. This research includes the development and application of high repetition static IG using semiconductor switches and simple control methods.

1. (Operation) Mechanism and Circuit Diagram

To generate a high voltage, there is a multistage high voltage generator (one type of which is a Marx circuit), which charges multiple capacitors in parallel to Vc and outputs it in series instantaneously by the operation of a switch connecting the capacitors, thus a high voltage (- n × Vc) is generated.

In the upper right figure, the static IG with n = 10 stages developed in the laboratory is operated by the switches of the IGBT 1 and 2 on the left side of the figure, and at the right-hand side capacitors C1 -C10 is connected in parallel with the inductance L. and the circuit containing diodes in parallel are charged at high speed and high efficiency (Vc). Turning on the switch at the lowest stage labeled Thy1 from the outside, the switches on the 2nd stage and above turn on automatically, all capacitors are switched in series, and the load is applied with negative high voltage. Figure 2 is an actual photograph of the static IG with 30 stages in total with 5 stages per board.

2. Output Characteristics and Applications

Figure 3 shows the waveform of the output voltage when the capacitor is charged at Vc = 1.0 kV, 1.5 kV, 1.7 kV, 1.9 kV. In this case, the semiconductor switch uses an IGBT with a breakdown voltage of 2 kV and generates a voltage of 50 kV at the maximum.

In addition, Figure 4 shows the case where a dye (indigo carmine) is decomposed by streamer discharge generated by applying a high repetitive high voltage using this power supply to the electrode of a needle-to-plate in a liquid.

3. Future Plans

We are engaged in research and development focusing on the following points.

• Loss reduction and simplification of each stage gate circuit.

• Improvement of switching properties such as rize time constant.

• Application using high repetitive, high voltage power supply.