大气压空气中纳秒脉冲介质阻挡放电特性分析

Characteristics of Nanosecond-pulse Dielectric Barrier Discharge in Atmospheric Air

介质阻挡放电(dielectric barrier discharge,DBD)是产生低温等离子体的重要方法,纳秒脉冲条件下DBD与普通交流下的放电不同。通过单极性纳秒脉冲激发大气压空气中DBD,计算纳秒脉冲DBD的电气参数,与交流或微秒脉冲放电的电气参数相比较,并对比放电图像与电流波形的关系,探讨了放电机制。研究结果表明,纳秒脉冲DBD的放电电流呈双极性,气隙上发生2次放电过程,其电气参数高于常规交流和微秒脉冲DBD的电气参数。随着空气间隙距离的增加,均匀放电向丝状放电的转化与电流脉冲波动相关。由于微放电持续时间与施加脉冲处于同一个数量级,且基本同时发生在气隙中,很难在同一位置上存在数个连续的微放电,这对放电的均匀性有利。

Dielectric barrier discharge （DBD） is an important method of generating non-thermal plasma, and DBD generated by nanosecond-pulse is different from that by conventional AC power source. Characteristics of DBD driven by repetitive unipolar nanosecond-pulses in atmospheric air were investigated, the electric parameters were calculated, and the comparison of electric parameters for DBD under AC, microsecond-pulse and nanosecond-pulse excitation was conducted. The relationship between the discharge images and current was obtained, and the discharge mechanism excited by nanosecond-pulse was also analyzed. Some experiment results were acquired, e.g. the measured discharge current exhibits bipolar pulses, which indicating two continuous discharges, and the electric parameters are higher than those under the excitation of AC or microsecond-pulse. Furthermore, with the increase of air gap spacing, the transition from the homogeneous to filamentary discharge is related to the fluctuation of discharge current. Because microdischarge duration and the width of pulse are on the same order under nanosecond-pulse excitation, the microdischarges take place synchronously, and it is difficult for consecutive occurrences on the same location, which has a positive influence on the discharge uniform.