微波电子回旋共振等离子体放电特性研究

STUDY ON THE CHARACTERISTICS OF MICROWAVE ECR PLASMA DISCHARGE

为了深刻理解微波电子回旋共振(ECR)等离子体的物理机制、瞬态过程以及空间分布特性,首先利用光栅光谱仪对ECR氮等离子体发射光谱进行了研究,然后利用朗缪尔双探针测量了装置反应室内等离子体密度的空间分布,并分析了放电气压对等离子体空间分布的影响.结果表明:ECR氮等离子体中主要发生的是碰撞激发、碰撞电离和碰撞离解等微观过程,且等离子体的主要成分是激发态的N2+;受磁场梯度影响的反应室上游区,等离子体分布不均匀,受等离子体密度梯度影响的下游区,等离子体则具有良好的均匀性;对于特定的微波功率(PW=400 W),放电气压存在一个最佳值(P=0.07 Pa).

In order to understand the physical mechanism, transient processes and spatial distribution of the microwave electron cyclotron resonance （ECR） plasma, a typical emission spectrum obtained from the nitrogen ECR plasma by a grating monochrometer has been studied, and the influence of discharge pressures on it were also and the plasma density distribution in the reaction chamber diagnosed using a double Langmuir probe. The results demonstrate that there mainly exist excitation collisions, ionizing collisions and dissociation collisions in the nitrogen ECR plasma, and the dominating reactive species are high excited nitrogen molecular ions. Under the influence of magnetic field, the ECR plasma in the upstream region has poor uniformity distribution , whereas the plasma in the downstream region, under the influence of the plasma density gradient, takes on a homogeneous distribution. The discharge pressure has a best value （P =0. 07 Pa） with a fixed microwave power （Pw =400 W）.