电压对射频空心阴极放电特性的影响
Influence of the Voltage on the Plasma Characteristics in the Radio Frequency Hollow Cathode Discharge
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摘要: 为了提高射频空心阴极放电中的等离子体密度,采用粒子网格(Particle-In-Cell,PIC)法与蒙特卡洛碰撞(Monte-Carlo-Collision,MCC)模型相结合的方法(PIC/MCC法),研究了空心电极上施加的射频电压变化对射频空心阴极放电特性的影响。研究结果表明,和平板电极容性耦合射频放电相比,射频空心阴极放电能获得更高的电子密度。随着射频电压的增加,孔内的鞘层电场和鞘层电势降均增加,引起鞘层振荡加热和二次电子加热的增强,这将增大电子密度。此外,在本文模拟所设置的电压范围内(150-210 V),随着电压的增加,空心阴极效应(hollow cathode effect,HCE)的强度也增加,这也将增大电子密度。同时,随着射频电压的增加,等离子体在孔内的深度也增加,这将进一步增大电子密度。因此,提高射频电压是在空心电极孔内外获得高密度等离子体的有效方法。Abstract: In order to increase the plasma density in the radio frequency(RF)hollow cathode discharge(HCD),a two-dimensional Particle-In-Cell/Monte-Carlo-Collision(PIC/MCC)model was employed to study the effect of the RF voltage applied to the hollow electrode on the discharge characteristics in the RF-HCD.The research results show that,compared with the capacitively coupled radio frequency discharge with the plane electrodes,the RF-HCD can obtain a higher electron density.With the increase of the RF voltage,the sheath electric field and the sheath potential drop in the hole both increase,causing the enhancement of the sheath oscillating heating and the secondary electron heating.The enhancement of the sheath oscillating heating and the secondary electron heating will increase the electron density.In addition,within the voltage range(150-210 V)set by the simulation in this article,as the voltage increases,the intensity of the hollow cathode effect(HCE)also increases,which will also increase the electron density.Simultaneously,as the RF voltage increases,the depth of the plasma in the hole also increases,which can further increase the electron density.Therefore,increasing the RF voltage is an effective way to obtain high-density plasma inside and outside the hollow electrode hole.