Development of an Infrared Thomson Scattering System for Diagnostics of Processing Plasmas

当激光汤姆森散射被应用于使用反应性气体来释放电荷时，激光脉冲可能会使电荷失效是一个强有力的可能性。在激光可能产生的最大反应中，就像从负离子和分子的光分离中产生的电子的光分解，有一个光子能量阈值。本项目旨在开发一个新的汤姆森散射系统，基于红外（低光子能量）激光器，用于反应性等离子体的诊断，以及激光脉冲干扰放电的实验条件。此外，电子密度的低探测极限的改进已经完成。后续的结果已经收到了。（1） A Thomson scattering measurement system based on a1.064 μm wavelength YAG laser was constructed。散射测量显示了这些结果是可与那些使用过的可见激光器的汤姆森散射系统相比较的。（2） No evidence of laser perturbation was Observed of ICP discharges using CF D24 D2 gas。However，激光渗透在532纳米的波长下观察到微波放电等离子体在CHI-D24-Y-D2气体的压力下产生。这些现象应该在以后的细节中进行调查。（3） The lower detection limit of electron density was improved down to 5 x10-D115-D1 m-D1。这主要是通过最大化检测固体角度，增加数据累积的射击数字，并使用一个单色色谱仪，其中有一个特定的高闪光灯拒绝的特征。

When laser Thomson scattering is applied to discharges using reactive gases, there is a strong possibility that the laser pulse may perturb the discharges. Most of the reactions that a laser might induce, such as photo-detachment of electrons from negative ions and photo-dissociation of molecules, have a photon energy threshold. This project aimed to develop a new Thomson scattering system based on an infrared (low photon energy) laser for diagnostics of reactive plasmas and to examine conditions that the laser pulse disturbs the discharges. Also, the improvement of the lower detection limit for electron density was performed. Following results were obtained.(1) A Thomson scattering measurement system based on a 1.064 μm wavelength YAG laser was constructed. Scattering measurements showed that the results were comparable with those obtained using previous Thomson scattering systems that used visible lasers.(2) No evidence of laser perturbation was observed of ICP discharges using CFィイD24ィエD2 gas. However, the laser perturbation was observed at a wavelength 532 nm for a microwave discharge plasma produced in CHィイD24ィエD2 gas at a pressure of 20 Torr. These phenomena should be investigated in detail hereafter.(3) The lower detection limit of electron density was improved down to 5x10ィイD115 ィエD1 mィイD1-3ィエD1. This was achieved mainly by maximizing the detection solid angle, increasing shot numbers for data accumulation, and using a monochromator which has a specific characteristic of high stray light rejection.