负直流电晕流注脉冲特性随气压和湿度变化的规律

Variation of the Characteristics of Negative DC Corona Streamer Pulse With Air Pressure and Humidity

为得到负直流电晕流注脉冲特性随着气压和湿度变化的规律,建立考虑气压和湿度影响的流体模型,分别利用通量校正运移算法和分块方法求解了1维连续性方程和2维泊松方程。在人工气候罐中,利用棒–板电极,测量不同气压和湿度下的负直流电晕脉冲幅值和重复频率。计算和实验结果表明:特里切尔脉冲平均幅值及分散度随气压和湿度增大而减小。随着气压降低,电子密度增大,电导率升高,电流幅值增大。随着湿度升高,复合和附着作用增强,电子密度减小,电导率降低,电流幅值减小;同时,流注通道中包含的负离子数目减少,对阴极附近场强的影响减弱,使得阴极附近电场在负离子电荷迁移距离较短的情况下便满足新的特里切尔脉冲放电的要求,脉冲的重复频率增大。

A fluid model of negative DC streamer discharge was set up to obtain the characteristics of negative DC corona streamer pulse under various pressure and humidity, and the flux-corrected transport algorithm and method of disks were applied to solve the one-dimension continuity equations and two-dimension Poisson＇s equation respectively. The amplitude and frequency of negative DC corona streamer pulse under different pressure and humidity were measured using a point/plane electrode system in the artificial climate chamber. Some conclusions were drawn as follows： the average amplitude of Trichel pulse and its variance decrease with the rise of pressure and humidity; the increase of current amplitude with the fall of pressure is mainly brought about by the enlargement of electrons＇ density and conductivity in streamer channel due to the decrease of attachment rate; the decrease of current amplitude with the rise of humidity is mainly caused by the fall of electrons＇ density and conductivity in streamer channel due to the increase of recombination and attachment rate. Besides, the number of negative ions in streamer channel decreases with the rise of humidity, and the influence on electric field near the cathode becomes weaker. As a result, the electric field near cathode could meet the demand of emerging a new Trichel pulse discharge as the negative ions migrate from the cathode to a shorter distance, then the streamer pulse frequency increases.