A repetitive microsecond pulse generator for atmospheric pressure plasma jets

Compared with other non-thermal plasma sources, the atmospheric-pressure plasma jet (APPJ) has advantages on simple structure, low temperatures, strong chemical activities, and convenient handling, all of which have attracted much attention. The power sources play an important role on the characteristics and the applications of the APPJ. In this article, a compact repetitive microsecond-pulse generator is designed for exciting the APPJ in helium and argon. The microsecond-pulse generator can produce repetitive pulses with output voltages of up to 20 kV, pulse width of ~8 μs, and pulse repetition frequencies (PRFs) of 1 Hz ~2 kHz. Using the designed repetitive microsecond-pulse generator, the characteristics of the APPJ are investigated by measuring the voltages and currents and obtaining images of the discharges. Experimental results show that the microsecond-pulse generator has been successfully used to sustain stable APPJs both in helium and argon. The shape of the output voltage pulses may change as the applied voltage increases. Nevertheless, the output voltages are stable at all PRFs when the applied voltage is fixed. Furthermore, the effects of flow rate, the applied voltage, and the PRF on the He/Ar APPJ are investigated. Results show that it is more likely to generate a He APPJ rather than an Ar APPJ under microsecond-pulse excitation. The length of the plasma plume is slightly affected by the PRF both in the He APPJ and the Ar APPJ.