Langmuir探针诊断低压氢等离子体电子密度与温度
Langmuir probe diagnosis of hydrogen plasma induced by helicon-wave under low pressure
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摘要: 为研究实验参数对螺旋波诱导的低压氢等离子体状态的影响，用Langmuir探针对等离子体伏安特性曲线进行了原位诊断，采用双曲正切函数的指数变换模型拟合曲线，根据Druyvesteyn方法得到状态参数电子密度、有效电子温度和电子能量几率函数，分析了它们随实验参数的变化规律。结果表明：射频输入功率、气压和约束磁场对等离子体状态有较大影响。随着射频射入功率增大，放电模式发生转变，电子密度跳跃增长；随着气压增大，电子密度先增大后减小，1.5 Pa为最佳电离气压，随约束磁场的增强呈线性增长；有效电子温度随功率和气压的增大而下降，随约束磁场的增强线性降低，电子能量几率函数曲线峰位和高能部分都向低能移动，与有效电子温度变化规律吻合。
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关键词:
- 螺旋波等离子体 /
- Langmuir探针 /
- 双曲正切函数 /
- Druyvesteyn方法 /
- 状态参数
Abstract: The current-voltage characteristic of hydrogen plasmas induced by helicon waves was measured in situ by a Langmuir probe under low pressure. According to Druyvesteyn method, raw data were fitted by an exponential transformation to a tangent hyperbolic function. Electron density, effective electron temperature and electron energy probability function(EEPF) were calculated from the fitted curves. The variation law of electron density, effective electron temperature and EEPF was analyzed in relation to different experimental parameters. The results demonstrate that RF power, gas pressure and controlled magnetic field have significant effects on state parameters of plasma. Electron density jumps with the increase of RF power because of the transition of mode, and it increases linearly with con-
Key words:
- helicon plasma /
- langmuir probe /
- tangent hyperbolic function /
- druyvesteyn method /
- state parameter
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