Study on Monitoring of Radio Frequency Glow Discharge Plasma

提出了利用平行阴阳极之间的光发射剖面(OEP)来监测和表征射频辉光放电等离子体的方法，并对H2、N2和Ar辉光放电进行了检测。由于离子鞘与等离子体的边界恰好位于极坐标中的峰值位置，因此用自聚焦极坐标来估算阴极鞘宽是非常容易的。只有H_2放电有一个双峰和一个与边界相对应的第二峰。用朗缪尔探针法测量了等离子体参数，发现H_2和N_2等离子体中的相对平均电子能量Te可用离子鞘宽度与Te的关系来估算。等离子体密度也可以用阴极负电位Vc和Is来估计。为了实际的掌纹处理，还研究了用CCD图像传感器快速测量OEP的方法。尽管由于难以通过光学透镜在二维图像上表示平行电极，所以CCD技术带来了一些偏差，但也需要评估精确的离子鞘宽度，特别是对于相对较窄的鞘宽度。采用面阵CCD图像传感器，配合焦距为105 mm的微透镜，成功地实现了鞘宽的测量。

Optical emission profile (OEP) between parallel cathode and anode electrodes was proposed for monitoring and characterizing radio frequency (rf) glow discharge plasma, and H_2, N_2 and Ar glow discharges were examined. The cathode sheath width was evaluated quite easily by the OEP, because the boundary of the ion sheath and the plasma lay just at a peak position in the OEP. Only H_2 discharge has a doublet peak and a second peak corresponded to the boundary. The plasma parameters are measured by the Langmuir probe method, and the relative mean electronenergy Te in H_2 and N_2 plasmas is found to be evaluated by the ion sheath width Is with a relationship Te Is. The plasma density can also be estimated by both the cathode negative potential Vc and Is.The quick measurement of the OEP using a CCD image sensor was also examined for the practical palsma processings. Although the CCD technique brought the somewhat deviated OEP because of the difficulty in the representation of the parallel electrodes at a two dimentional image through an optical lens, the precise ion sheath widths were also to be evaluated, especially for relatively narrow sheath widths. The CCD image sensor combined with a macro-lens with the focal distance of 105mm was quite successful for measuring the sheath width.