脉冲调制条件下介质阻挡特高频放电特性的数值模拟

大气压条件下,引入脉冲调制是一种有效地提高射频放电稳定性的方法.已有的研究表明,当电源频率提高到甚高频乃至特高频频段的时候,在脉冲调制条件下射频放电会表现出新的放电现象与放电规律.本文借助于流体模型,研究了当电源频率提高至500 MHz,脉冲调制条件下介质阻挡放电的放电特性.数值计算表明,在电压开启的第一个周期内的正负半周期会各出现一次大电流放电的现象,瞬时阳极鞘层的电场结构及介质表面电荷对该现象的产生具有重要影响;并深入研究了占空比、调制频率与电压调制比对该大电流脉冲的影响,以及大电流脉冲在放电从脉冲调制状态过渡到连续状态逐渐消失的过程.本研究将对深入理解脉冲调制参数对介质阻挡放电的影响起到积极作用.

Numerical study on discharge characteristics in ultra-high frequency band modulated by pulses with electrodes covered by barriers

Pulse-modulated discharge is an effective way to improve the stability of radio-frequency(rf)discharges.Previous studies have shown that with the power frequency increasing to the ultra-high frequency(UHF)band,the introduction of pulse modulation in rf discharges will bring about new discharge behaviors.In this paper,the fluid model is adopted to numerically investigate the new discharge characteristics in dielectric barrier discharges(DBDs)with the rf frequency larger than 500 MHz.A very large current peak occurs in the first positive and negative half cycle during the power-on phase,respectively.The spatial structure of electric field is given to further understand the underpinning physics of the large current peaks.Furthermore,the effects of duty cycle,modulation frequency and voltage modulation rates on the large current peaks are examined based on the computational data.This numerical study will deepen the understanding of DBDs modulated by pulses in the UHF band.