Comparison of Langmuir probe and laser Thomson scattering for electron property measurements in magnetron discharges
Comparison of Langmuir probe and laser Thomson scattering for electron property measurements in magnetron discharges
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DOI：
10.1063/1.5109621
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发表时间：
2019-07
影响因子：
2.2
通讯作者：
P. Ryan;J. Bradley;M. Bowden
中科院分区：
文献类型：
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作者：
P. Ryan;J. Bradley;M. Bowden
在弱磁化等离子体条件下，利用平面非平衡磁控管对朗缪尔探针和激光汤姆逊散射所做的电子特性测量进行了比较，目的是评估探针诊断的准确性。测量是在磁场结构内的几个位置进行的，包括放电轴上的磁场零点区域（≲1 mT）以及磁场高达33 mT的最后一个闭合磁通面边界内部。在高功率脉冲磁控溅射过程中，两种诊断方法吻合良好，但在直流磁控管运行时，即使在磁场零点处也观察到了显著差异。对于某些放电条件，使用离子和电子收集理论时，汤姆逊散射确定的电子密度比朗缪尔探针获得的等离子体密度大一个数量级以上。此外，探针确定的电子能量分布函数的低能部分有所缺失。对差异的可能原因进行了讨论，结论是等离子体受到了探针杆的显著扰动。本研究中测量的等离子体密度范围和电子温度分别为0.4 - 54×10¹⁷ m⁻³和0.2 - 5.9 eV。
Electron property measurements made by Langmuir probes and laser Thomson scattering have been compared in weakly magnetized plasma conditions using a planar unbalanced magnetron with the aim of assessing the accuracy of the probe diagnostic. The measurements were performed at several locations within the magnetic field configuration, the magnetic null region ( ≲ 1 mT) on the discharge axis and inside the last closed flux surface boundary with fields up to 33 mT. There was good diagnostic agreement during High Power Impulse Magnetron Sputtering, but significant discrepancies were observed for DC magnetron operation, even at the magnetic null. For some discharge conditions, the electron density determined by Thomson scattering was over an order of magnitude greater than the plasma density obtained from the Langmuir probe, using both ion and electron collection theories. In addition, the low energy part of the electron energy distribution function determined by the probe was depleted. The possible reasons for the discrepancies are discussed, with the conclusion being that the plasma was significantly perturbed by the probe stem. The range of plasma densities and electron temperatures measured in this study were 0.4–54 × 1017 m−3 and 0.2–5.9 eV, respectively.