An inversion technique to obtain full poloidal velocity profiles in a tokamak plasma
An inversion technique to obtain full poloidal velocity profiles in a tokamak plasma
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获得托卡马克等离子体中全极向速度剖面的反演技术
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发表时间：
1997
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通讯作者：
R. Bell
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文献类型：
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作者：
R. Bell
通过对托卡马克等离子体中扩展发射源的线积分测量，建立了一种反演技术来计算杂质离子的局部极向旋转速度。该技术可以恢复由于磁场线曲率而失去的径向空间分辨率。通过中性束的电荷交换发射，它可以用来获得等离子体整个小半径的极向速度分布，而不需要限制中性束的高度来定位发射。该技术包括两个类abel矩阵反演，分别得到发射率和速度加权发射率，并由此得到速度。中性光束的使用打破了假定的对称性，但光束沉积和几何知识允许生成类似的矩阵。用高度为80 cm的切向中性光束模拟TFTR托卡马克的极向旋转诊断，验证了该反演技术。需要两个相反的垂直视图来处理电荷交换截面的影响，这可能导致表观速度大大超过预期的极向速度。在等离子体中心附近，反演过程的模拟误差约为1.5 km/s。
An inversion technique has been developed to calculate local poloidal rotation velocities of impurity ions from line-integrated measurements of an extended emission source in a tokamak plasma. This technique can recover radial spatial resolution that is lost due to the curvature of the field lines. With charge exchange emission from neutral beams, it can be used to obtain poloidal velocity profiles across the entire minor radius of the plasma without requiring restricted neutral beam height to localize the emission. The technique consists of two Abel-like matrix inversions to obtain the emissivity and the velocity-weighted emissivity from which the velocity is obtained. Use of the neutral beams breaks the assumed symmetry, but knowledge of the beam deposition and geometry allow analogous matrices to be generated. The inversion technique is demonstrated with a simulation of a poloidal rotation diagnostic for the TFTR tokamak with tangential neutral beams with a height of 80 cm. Two opposing vertical views are required to handle effects of the charge exchange cross section, which can cause apparent velocities greatly in excess of expected poloidal velocities. The simulated errors due to the inversion process are about 1.5 km/s near the plasma center.