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空心阴极自脉冲放电的时空演化特性

Temporal and Spatial Evolution of Self-Pulse in Hollow Cathode Discharge

  • 摘要: 本文利用圆筒形空心阴极放电结构,研究了自脉冲放电等离子体参量的时空演化特性。在气压为133 Pa的氩气环境下获得了稳定的自脉冲放电,同时将测量得到的极间电压作为输入电势,利用流体模型进行了空心阴极自脉冲放电的数值模拟研究。模拟得到了放电电流、电势、电子密度、电场和净电荷密度的时空分布特性。结果表明等离子体参量随时间成周期性变化。自脉冲现象为由孔外低电流、低径向电场强度、低电子密度、低净电荷密度放电模式向孔内高电流、高径向电场强度、高电子密度、高净电荷密度放电模式的一个往复转换的过程。自脉冲不同阶段放电模式的转换与平均电流有关。当自脉冲放电处于电流峰值时为具有较强空心阴极效应的正常辉光放电模式。自脉冲处于低电流时的放电模式与平均电流有关。当平均电流较低时,自脉冲放电在阳极和孔内阴极附近往复移动;此状态下瞬时电流最低值时放电处于汤生放电模式。当平均电流较高时,自脉冲放电在阴极孔口和孔内阴极附近往复移动;此状态下瞬时电流最低值时阴极附近的阴极鞘层基本形成。

     

    Abstract: The temporal and spatial evolution of plasma parameters in self-pulsing discharge is studied experimentally and simulated in a cylindrical hollow cathode discharge structure. Stable self-pulsing discharge is obtained in argon with a pressure of 133 Pa. Taking the measured voltage between two electrodes as the input potential, the self-pulsing discharge in a hollow cathode is simulated by using a fluid model. The temporal and spatial distributions of discharge current, potential, electron density, electric field and net charge density are obtained.Resultsshow that the self-pulsing phenomenon is a transitional process from the discharge mode of low current, low radial electric field, low electron density and low net charge density outside the hole to the discharge mode of high current,high radial electric field intensity, high electron density and high net charge density inside the hole. The transition of discharge mode in different stages of self-pulse is related to the average current. When the self-pulsing discharge is at the peak current, it is a normal glow discharge mode with a strong hollow cathode effect. The discharge mode of the self-pulse at low current is related to the average current. When the average current is low, the self-pulse discharge moves from the anode to the region close to the cathode inside the hole. At this time, when the instantaneous current is the lowest, the discharge is in Townsend discharge mode. When the average current is high, the selfpulse moves from the cathode orifice to the region close to the cathode inside the hole. At this time, when the instantaneous current is the lowest, the cathode sheath near the cathode is basically formed.

     

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