The Numerical Simulation Of Pulse-modulated Radio-frequency Dielectric Barrier Atmospheric Pressure Glow Discharge

Atmospheric pressure radio-frequency glow discharges (RF-APGDs) free of need for a vacuum system, they work at atmospheric pressure. Because of the discharge device is not limited vacuum, they are beneficial to continuous production. For this reason, RF-APGDs are widely used in many fields, such as modification of materials, semiconductor etching and deal with harmful substances. One of the most important applications is in the biological medicine: RF-APGDs can deal directly with people or animals’body. However, due to the high power of radio-frequency, the discharge is not stable and easily transferred form glow to arc, which have high temperature easy to cause some thermal damage on the material surface. So how to control the stability of discharge under high intensity becomes one of problems in study.In this thesis, we investigate the pulse-modulated atmospheric pressure radio-frequency capacitively coupled argon plasma by one-dimensional collision-less fluid model.6kinds of primary particles and10key reactions including ionization and excitation are incorporated in the model. The study was divided into two parts. First, the effect of adding pulse power on discharge was investigated. This part mainly researches the variation of voltage, current density, particle densities, electron temperature and electric field during discharge ignition phase, radio-frequency power on and discharge extinguishment phase. Second, we study the influence of different pulse parameters on RF-APGDs. We consider the parameters including duty cycle, pulse on time, pulse frequency and so on.The simulation results show that the RF-APGDs parameters can be more easily and flexibly controlled when we use pulse modulation radio-frequency power. The distribution of time averaged particles density, electron temperature and electric field are the same with radio-frequency discharge which without pulse modulation. The voltage and current density increase (decrease) rapidly with the power on (off). Due to diffusion effect, electrons will move to dielectric-slab and acts as seed electrons for the ignition of the next discharge event.The study also found that electron and argon metastable molecular density will be increased with the time of pulse on, while have little impact on electron temperature and electric field. Change pulse frequency when fixed pulse duty cycle20%, we found that the discharge current magnitude change slowly when pulse frequency less than20KHz, however, discharge current magnitude decrease rapidly when pulse frequency more than20KHz. Increase the duty cycle to90%, we learned that the pulsed modulation frequency does not effect the magnitude of discharge current.