Optimum circuit design for the detection of laser photodetachment signals
Optimum circuit design for the detection of laser photodetachment signals
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DOI：
10.1088/0963-0252/22/1/015014
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发表时间：
2012-12
影响因子：
3.8
通讯作者：
P. Bryant;J. Bradley
中科院分区：
文献类型：
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作者：
P. Bryant;J. Bradley
激光光剥离是一种广泛应用的低温等离子体源负离子检测技术。在一种常见的方法中，通过入射激光束从负离子光分离的电子由偏置在局部等离子体电势之上的朗缪尔探针收集。通过朗缪尔探针馈通和互连电缆（传输电路）传输的光分离电流信号由检测电路转换成电压信号。负离子密度和温度（使用双脉冲技术）由信号处理获得。电路分析的信号采集电路，传输和检测部分，是用来获得的光剥离信号的无失真传输的设计标准。在常规低压磁控管系统中，实验研究了改变电路参数的影响。结果表明，电路参数选择不当会导致光剥离信号的畸变，从而导致负离子浓度和温度的测量误差较大。
Laser photodetachment is a widely used diagnostic technique for the detection of negative ions in low-temperature plasma sources. In one common method electrons, photodetached from the negative ions by an incident laser beam, are collected by a Langmuir probe biased above the local plasma potential. The photodetachment current signal, transmitted through the Langmuir probe feedthrough and interconnecting cables (transmission circuit), is converted into a voltage signal by a detection circuit. The negative ion density and temperature (using the two-pulse technique) are obtained from signal processing. Circuit analysis of the signal acquisition circuit, both transmission and detection parts, is used to obtain the design criteria for the undistorted transmission of the photodetachment signal. The effects of changing the circuit parameters from their optimum values are investigated experimentally in a conventional low-pressure magnetron system. The results show that an inappropriate choice of the circuit parameters can lead to significant distortion of the temporal photodetachment signal, leading to large measurement errors of the negative ion density and temperature.