Laser Thomson scattering measurements of negative ion density in a glow discharge plasma
Laser Thomson scattering measurements of negative ion density in a glow discharge plasma
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DOI：
10.1088/0963-0252/11/1/307
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发表时间：
2002-02
影响因子：
3.8
通讯作者：
Masanori Noguchi;K. Ariga;T. Hirao;P. Suanpoot;Y. Yamagata;K. Uchino;K. Muraoka
中科院分区：
文献类型：
--
作者：
Masanori Noguchi;K. Ariga;T. Hirao;P. Suanpoot;Y. Yamagata;K. Uchino;K. Muraoka
激光汤姆逊散射(LTS)为测量辉光放电等离子体中的负离子密度提供了一种有用的手段。由于饱和能量密度很低，以至于在用于LTS测量的探测激光脉冲的非常早期阶段就发生了完全的光剥离，所以激光脉冲的主要部分是被光剥离的电子和在放电中已经产生的电子所散射的汤姆森散射。光分离电子的能量低于负离子的光子能量和电子亲和力之间的能量差，由此产生的汤姆森散射出现在差能以下。在20mTorr的Ar(80%)/O2(20%)混合气体中，用一束波长为532 nm的激光对感应耦合等离子体进行二次倍频，得到负离子密度为1.5×10~(17)m~(-3)，相当于4.1×10~(17)m~(-3)电子密度的37%或负电荷(电子和负离子)的27%。
Laser Thomson scattering (LTS) is shown to provide a useful means for measurements of negative ion density in a glow discharge plasma. Because the saturation energy density is so low that complete photo-detachment occurs at a very early stage of the probing laser pulse for the LTS measurement, the main part of the laser pulse is Thomson scattered by the photo-detached electrons as well as those already generated in the discharge. The energies of photo-detached electrons are below the energy difference between the photon energy and the electron affinity of the negative ions, and Thomson scattering from these appears below the difference energy. The principle has been tested using the second harmonic of a YAG laser light (532 nm) against an inductively coupled plasma operated in a mixture of Ar(80%)/O2(20%) at a pressure of 20 mTorr, and yielded the negative ion density of 1.5×1017 m-3, which amounted to 37% of the electron density of 4.1×1017 m-3 or 27% of the negative charges (electrons and negative ions).