大面积等离子体片分层现象的实验研究

Experimental study of Stratification of Large Planar Plasma Sheet

为了研究大面积等离子体片的分层特性,利用脉冲磁约束线形空心阴极放电装置,在150 Pa氦气中产生了持续时间为200μs、面积为60 cm×60 cm的大面积等离子体片。采用快帧法和旋转空心阴极法利用郎缪尔探针首次获得了等离子体片分层时厚度方向电子密度分布及其演化构成的二维分布图;基于获得的二维分布图,研究了分层等离子体片厚度方向电子密度的分布特征与磁场强度和放电电流的关系。实验发现,等离子体片分层时厚度方向电子密度呈现双峰曲线分布特征;当放电电流为2 A,磁场强度为1.5×10^(-2),2.25×10^(-2),3×10^(-2)T时,双峰间距分别为0,3.2,8.4 mm;当磁场为3×10^(-2)T,电流为1,2,3,4 A时,双峰间距分别为8.6,8.2,6.8,5 mm。结果表明:分层等离子体密度峰值间距随着磁场的增强和放电电流的降低而增大。

The stratification of the largeplanar plasma sheet,60 cm ×60 cm in size,200 μs for duration,and generated by pulsed magnetic confinement linear hollow cathode discharge at 150 Pa,was experimentally investigated.The evolution of the 2-D electron density distribution in sheet＇ s normal direction was diagnosed with Langmuir probe and recorded with a fastoscilloscope in the rotating hollow cathode method.The impact of the magnetic field and discharge current on the electron density characteristics was studied.The results show that the magnetic field and discharge current significantly affect the stratified electron densitywith a bimodal distribution.For example,generated at 2 A,as the magnetic field intensity increased from 0.0 to 3 × 10^-2 T,the bimodal-peak distance increased from 0.0 to 8.4 mm;whereas at 3 × 10^-2 T,as the discharge current increased from 1 to 4 A,the distance decreased from 8.6 to 5 mm.In a word,a combination of an increased magnetic field and a decreased discharge current widens the bimodal peaks.