Exploiting Zeeman effect symmetries to measure particle velocities in magnetized plasmas
Exploiting Zeeman effect symmetries to measure particle velocities in magnetized plasmas
复制标题
利用塞曼效应对称性测量磁化等离子体中的粒子速度
DOI：
10.1088/1361-6501/ab0e90
复制
发表时间：
2019
影响因子：
2.4
通讯作者：
Winters, V
中科院分区：
文献类型：
--
作者：
Green, J;Schmitz, O;Severn, G;Winters, V
使用激光诱导荧光（LIF）获得磁化等离子体中的流速的任务通常由于需要从由于磁场引起的效应（例如，塞曼效应）去卷积速度分布函数（VDF）而变得复杂。因此，经常需要精确了解局部磁场强度和由此产生的线路结构。这项工作表明，实际上塞曼效应没有影响的第一时刻的VDF，只要集成覆盖所有和组件。以这种方式，可以通过计算LIF信号的一阶矩直接获得，而无需去卷积也无需独立的磁场强度知识。这被证明是相当于找到的LIF信号的对称速度分布函数，如麦克斯韦分布的情况下，和组之间的中点。利用激光诱导荧光（LIF）泵浦线性螺旋等离子体中单电离氩的跃迁，实验验证了这一点。通过偏振入射激光以独立地激发和跃迁并测量荧光响应，通过取和分组之间的中点来测量多普勒频移。使用这种新的方法测量的离子速度进行比较，通过拟合卷积的配置文件LIF响应和协议之间的两种方法是在10%以内，但与新的方法具有的不确定性，这是一个因素的两个更少，需要更少的计算。这种比较还表明，塞曼分裂的简并能量状态拓宽了LIF响应，并可以产生高估的离子温度，T i，如果LIF信号与纯高斯曲线拟合。我们发现高估的数量级为10%。
The task of obtaining flow velocities in a magnetized plasma using laser induced fluorescence (LIF) is often complicated by the need to deconvolve the velocity distribution function (VDF) from effects due to magnetic fields, for example, the Zeeman effect. Hence, precise knowledge of the local magnetic field strength and the resulting line structure is often required. This work demonstrates that in fact the Zeeman effect has no impact on the first moment of the VDF, so long as the integration covers all and components. In this way, can be obtained directly by calculating the first moment of the LIF signal, without deconvolution nor independent knowledge of the magnetic field strength. This is shown to be equivalent to finding the midpoint between the and groups of the LIF signal in the case of symmetric velocity distribution functions, such as a Maxwellian distribution. This fact was experimentally verified by employing LIF to pump the transition in singly ionized argon in a linear helicon plasma. By polarizing the incident laser light to excite the and transitions independently and measuring the fluorescence response, the Doppler shift is measured by taking the midpoint between the and groupings. Ion velocities measured using this new method are compared with those obtained by fitting a convolved profile to the LIF response and agreement between both methods is within 10%, but with the new method having an uncertainty that is a factor of two less and requiring less computation. This comparison also demonstrates that the Zeeman splitting of the degenerate energy states broadens the LIF response and can yield an overestimate of the ion temperature, T i, if the LIF signal is fit with a pure Gaussian curve. We show the overestimate is on the order of 10%.
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密度波动引起的粒子和波散射
DOI：
--
发表时间：
1995
期刊：
影响因子：
--
作者：
D. Edrich
通讯作者：
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DOI：
--
发表时间：
2008
期刊：
影响因子：
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作者：
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影响因子：
1.6
作者：
T. Steinberger;Mikal T. Dufor;D. Thompson;E. Scime
通讯作者：
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影响因子：
3.8
作者：
Chen, Francis F.
通讯作者：
Chen, Francis F.