Real-time feedback control of millimeter-wave polarization for LHD.
Real-time feedback control of millimeter-wave polarization for LHD.
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DOI：
10.1063/1.3073735
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发表时间：
2009-01
期刊：
影响因子：
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通讯作者：
F. Felici;Timothy Goodman;O. Sauter;T. Shimozuma;S. Ito;Y. Mizuno;Shin Kubo;T. Mutoh
中科院分区：
文献类型：
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作者：
F. Felici;Timothy Goodman;O. Sauter;T. Shimozuma;S. Ito;Y. Mizuno;Shin Kubo;T. Mutoh
电子回旋加热（ECH）在磁聚变装置中有着广泛的应用，而注入毫米波束的极化对束流能量的传输和等离子体的吸收起着至关重要的作用。这种偏振可以通过放置在传输线中的光栅反射镜偏振器来调节，该传输线将微波从电源传送到等离子体。在诸如大螺旋装置（LHD）和ITER的长脉冲装置中，期望跟踪等离子体中的变化并在真实的时间内调节ECH的极化，以便保持吸收尽可能高并避免可能导致容器部件过热的穿透。为此，设想了一种实时反馈控制方案，其中吸收效率的测量可以用于将偏振镜的取向朝向最佳调整。这种设置已在低功率测试台中进行了测试，为将来在LHD ECH系统中实施做好准备。结果表明，一个简单的搜索算法是有效的，原则上可以用来控制吸收效率或线偏振角。
Electron cyclotron heating (ECH) is widely used in magnetic fusion devices, and the polarization of the injected millimeter-wave beams plays a crucial role in the propagation and absorption of the beam energy by the plasma. This polarization can be adjusted by grating mirror polarizers placed in the transmission lines which carry the microwaves from the power source to the plasma. In long-pulse devices such as the Large Helical Device (LHD) and ITER, it is desirable to track changes in the plasma and adjust the polarization of the ECH in real time such as to keep the absorption as high as possible and avoid shine-through which may lead to overheating of vessel components. For this purpose a real-time feedback control scheme is envisioned in which a measure of the absorption efficiency can be used to adjust the orientation of the polarizing mirrors toward an optimum. Such a setup has been tested in a low-power test stand as preparation for future implementation in the LHD ECH system. It is shown that a simple search algorithm is efficient and can in principle be used to control either the absorption efficiency or the linear polarization angle.