空气负电晕Trichel脉冲特性的实验研究

Experimental Study on the Characteristics of Negative-corona Trichel Pulses in Air

为得到Trichel脉冲放电的特征,采用针-板电极结构对空气中负电晕放电的特性进行了实验研究。利用示波器测试了放电电压、电流波形和脉冲频率,利用微安表测试了平均放电电流,并通过放电结构上并联电容的方法研究了外接电容对放电的影响。结果表明,空气负电晕Trichel脉冲非常稳定、规则;其脉冲频率随平均电流线性增大,针尖曲率影响频率上升的斜率,但电极间距、气压、并联电容对频率影响较小;不同放电条件下的Trichel脉冲波形基本相同,其上升沿几乎不随电流、间距、气压、针尖曲率和并联电容变化,但脉冲幅值随平均电流略有下降,同时与间距、气压、针尖曲率和并联电容等条件有关;Trichel脉冲是电晕区的特征放电,在给定电极条件下,其形成过程与平均电流(电压)、气压和外电路并联电容等无关。

In order to obtain some characteristics of Trichel pulses, we experimentally investigated negative corona in air using a needle-to-plate electrode. We measured the frequency, current, and discharge voltage of Trichel pulses using digi- tal oscilloscope, and average discharge current using micro-amperemeter. Through connecting capacitance in parallel to the discharge structure, we also investigated the influence of external capacitance on the discharge. The results show that the negative-corona Trichel pulses are stable and regular： their pulse frequency increases linearly with averaged current with a speed influenced by the tip radius of needle node, but it is barely influenced by the gap length, the air pressure, and the capacitance in parallel. The pulses also have the same current waveform under different conditions： their rising time hardly changes with the averaged current, the gap length, the air pressure, the tip radius, or the capacitance, and their am- plitude is influenced slightly by the averaged current as well as the other discharge conditions. It is concluded that Trichel pulses are characteristic discharge in corona region, and with a given electrode pair, their generation process is indepen- dent of discharge current, gas pressure, and external circuit.