| In recent years,atmospheric pressure non-equilibrium plasma jet(APNP-Js) as a low-temperature plasma technology gains a lot of attention. It has been widely used in surface treatment, biomedical applications of nanotechnology and other fields. Nanosecond pulse generator as a driver to produce APNP-Js excitation source has unique advantages. In order to obtain APNP-Js, a nanosecond pulse generator with a fast rising and falling edges needs to be designed. But the short lifetime and low repetition rate of the existing nanosecond pulse generator which is due to the restrictions of switches and other components, limited its application. Comparing with traditional gas switch generators using gas switches, the solid state generators have the merits of high reliability, long lifetime, simple circuit and less switching loss. In this paper, a kind of newly developed high performance all-solid-state nanosecond pulse generator based on Marx generator with chopping switches according to the nanosecond pulse generation principle and solid state switch technology is proposed.Firstly, the operation principle of the the all-solid-state nanosecond pulse generator with fast edge is detailedly described. Solid state Marx equivalent circuit model is methematically analyzed. The circuit simulation result with software Pspice validates the theoretical analysis. A solid-state Marx circuit model with chopping switches was established, and the characteristics of the traditional Marx circuit output were compared, the results show that the falling edge of output pulse waveform is greatly reduced because of the chopping switches. On this basis, the simulation analyzes the factors affecting nanosecond pulse generator main circuit output characteristics, the results show that the inherent characteristics of solid-state switches have a greater effect on the output pulse edge.The spurious parameters will slow output pulse edge and may cause waveform distortion.Then the specific design of each main part of the generator is presented. The calculation of components in the solid state Marx circuit is given according to the design requirement.of the generation of APNP-Js. The MOSFET's driver which is isolated by optical fibers and DC-DC converters is improved. Besides, some reasonable measure is used to minimize lead inductance.The control strategy using an FPGA as the implementation method. Using FPGA digital control and level conversion circuit as the core design of synchronous trigger module, and it can control trigger signal parameters adjusted. The protection control unit is to process the short circuit signals from the sensors and DC power fault signals. The general software flow chart of control system is detailedly introduced. The electromagnetic interference suppression method of solid state nanosecond pulse generator was studied, from the two ways to improve anti-jamming capability of the pulse generator.In this paper, the performance of nanosecond pulse generator is tested and the voltage and current waveform are measured. The test results show that it has the capability of producing repetitive pulses with a voltage up to 8kV, pulse width of 200~1000ns, rise time and fall time of 30 ns, repetition rate of 1~1000Hz and pulse number 1~10000 with various resistive loads. The generator with intelligent monitoring and control module can easily control pulse parameters. The designed nanosecond-pulse generator and needle-ring structure electrode which is based on dielectric barrier discharge structure are used to produce argon plasma jets into open air, and the experiments show that the nanosecond-pulse generator can sustain stable APPJs. The mechanism of the effect of the pulse power paraameters and gas environment on the length of plasma jets are preliminary studied.This researh is competent for further exploration of the characteristics of APNP-Js and lays the foundation for the biomedical application... |
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