离子振荡对低压脉冲负电性放电条件的影响

The effect of ion oscillation on the self-sustenance of low pressure electronegative discharge

为了研究该离子振荡及其对低气压负电性放电自持条件的影响,建立了一个整体模型描述低气压正负离子等离子体中离子振荡与少量电子的相互作用.在模型中引入参数r描述电子流体与电极碰撞后的动量保存(或损失)的程度.发现体系存在一个临界值r=rc,它导致了两种不同性质的电子损失机理.另一临界值r=4rc决定了两种不同的电子密度随时间增长的阈值.这使得该阈值随r非单调变化,进而导致RF负电性脉冲放电主动放电阶段初期的自持放电条件参数空间中可以存在间隙.PIC_MCC程序摸拟计算结果验证了这一结论.

It is a common way to obtain ion-ion plasmas from pulsed electronegative discharges. The pumping pulse can excite ion oscillation at the early active glow stage of a pulsed electronegative discharge. To study the ion oscillation and its influence on the self-sustaining condition of the discharge, a global model was developed to describe the interaction between ion oscillation and a small amount of electrons in a low-pressure ion-ion plasma. A parameter r was introduced in this model to describe the momentum residual/loss of the electrons after the collision with the electrodes. It was found a critical value r = rc that differentiates two electron loss mechanisms. Another critical value r = 4 rc determines two different threshold of the electron density growth. Thus, the threshold of the electron density growth is non-monotonously depend on r. Therefore, there might be a gap existing in the parameter space of the self-sustaining condition. The above result has been examined by a particle-in-cell simulation with Monte-Carlo collision （ PIC-MCC）.