脉冲调制占空比对常压射频辉光放电段特性影响的数值模拟

Numerical Simulation of the Dependence of Atmospheric Radio Frequency Glow Discharge Burst on the Duty Cycle of Pulse Modulation

射频放电段的起辉特性决定了常压脉冲调制射频辉光放电的放电特性和稳定性,通过建立常压氦气脉冲调制射频辉光放电的一维自洽流体数值模型,研究了射频放电段的放电时空演化过程,着重讨论了调制脉冲占空比对射频放电段的起辉过程和稳定放电特性的影响。当射频放电电压保持在680 V不变且占空比小于18.40%条件下,电子密度的空间分布表现为主等离子体均匀分布,射频放电段工作在起辉阶段;随着占空比的增长,射频放电段中的鞘层结构得到增强,在占空比大于18.4 0%条件下,电子密度的空间分布表现为电极两侧增强的双峰分布的情况,放电达到稳定状态。电子平均能量和电场强度的空间分布随占空比的变化规律,也揭示了射频放电段从起辉阶段到稳定放电状态的转变过程。研究结果为常压脉冲调制射频辉光放电的放电机制和稳定性控制提供了理论依据。

The discharge characteristics and stability of pulse modulated radio frequency（RF） atmosphere pressure glow discharge are determined by the discharge ignition of radio frequency discharge burst. A one-dimensional self-consistent numerical fluid model is developed for the pulse modulated radio frequency atmosphere pressure glow discharge in helium, which is employed for studying the spatiotemporal of radio frequency discharge burst on the duty cycle of modulation pulse. It shows that the spatial profile of electron density evolves with the duty cycle by keeping the voltage amplitude of 680 V.When the duty cycle is below 18.40%, the electron density is distributed uniformly in the plasma bulk,which suggests that the discharge burst operates in the ignition phase. On the other hand, the electron density moves towards two electrodes when the duty cycle is above 18. 40%, in which the sheath is enhanced, and the discharge evolves to the stable operation. The dependence of discharge evolution from ignition phase to stable operation on the duty cycle is also demonstrated by the spatial profiles of mean electron energy and electrical field. The research result provides the theoretical evidence for understanding of the discharge mechanism and manipulating the discharge stability of pulse modulated RF atmospheric glow discharge.