空心阴极自脉冲放电的电学特性

Electrical Characteristics of Self-pulse in Hollow Cathode Discharge

自脉冲是空心阴极放电中一种常见的不稳定现象,但是关于其特性和形成机理还存在一定争论。为了进一步揭示空心阴极放电自脉冲的放电机理,提高空心阴极放电的稳定性,在压强为1 330 Pa的氩气实验条件下测量得到了空心阴极放电的伏安特性曲线、自脉冲波形、自脉冲频率、等效电阻等放电特性。同时在实验数据的基础上,建立了一RC等效电路模型,将放电单元等效为一电容器和电阻的并联结构,自脉冲放电过程等效为一电容器的充放电过程,模拟再现了空心阴极放电中的自脉冲现象。实验结果表明:在自脉冲放电模式下,自脉冲频率随着平均电流的增高而升高;脉冲电流的最大值和最小值均随平均电流的增加而升高;脉冲电压的最低值基本不随平均电流变化,最高值随平均电流的增加先升高到一定值后然后基本保持不变;放电单元的最大和最小等效电阻值均随平均电流的增高而降低。利用RC等效电路模型比较好地再现了实验中的电流和电压波形。模拟结果表明,不同平均电流时,将放电单元充放电过程中的等效最大和最小电阻视为可变电阻去代替等效恒定电阻可以使模拟结果更接近实验结果,也更符合实际放电情况。

Self-pulse is a common unstable phenomenon in hollow cathode discharge. However, there are still some arguments on the characteristics and formation mechanism of self-pulse. In order to further reveal the discharge mechanism of self-pulse and increase the stability of hollow cathode discharge, we investigated the discharge characteristics such as the V-I curves, self-pulsing waveform, self-pulsing frequency and equivalent resistances of hollow cathode discharge in argon with a pressure of 1 330 Pa. On the basis of the experimental data, an RC equivalent circuit model was established to simulate the current and voltage waveforms of self-pulse in hollow cathode discharge, in which the discharge cell was modeled as a capacitor in parallel with a variable resistor and the self-pulsing discharge process can be described by the discharging and charging of a capacitor. The experimental results reveal that, in the self-pulsing regime, the frequency of self-pulses increases with the average discharge current, the maximum and minimum of the pulse current will increase with the average discharge current. The minimum value of the pulse voltage does not vary with the average current. The maximum value of pulse voltage increases with the average current to a certain value firstly, and then remains almost constant. The maximum and minimum equivalent resistances of discharge cell decrease with the average discharge current. The current and voltage waveforms in the experiment are well reproduced by using the RC circuit model. At the same time, the simulation results show that replacing the equivalent constant resistance with variable resistance can make the simulation results closer to the experimental results and more consistent with the actual discharge conditions.