Li G, Tan Y, Liu Y Q
Department of Engineering Physics, Tsinghua University, Beijing 100084, China.
Rev Sci Instrum. 2015 Aug;86(8):083502. doi: 10.1063/1.4927682.
Eddy currents have an important effect on tokamak plasma equilibrium and control of magneto hydrodynamic activity. The vacuum vessel of the Sino-UNIted Spherical Tokamak is separated into two hemispherical sections by a toroidal insulating barrier. Consequently, the characteristics of eddy currents are more complex than those found in a standard tokamak. Thus, it is necessary to measure and analyze the eddy-current distribution. In this study, we propose an experimental method for measuring the eddy-current distribution in a vacuum vessel. By placing a flexible printed circuit board with magnetic probes onto the external surface of the vacuum vessel to measure the magnetic field parallel to the surface and then subtracting the magnetic field generated by the vertical-field coils, the magnetic field due to the eddy current can be obtained, and its distribution can be determined. We successfully applied this method to the Sino-UNIted Spherical Tokamak, and thus, we obtained the eddy-current distribution despite the presence of the magnetic field generated by the external coils.
涡电流对托卡马克等离子体平衡和磁流体动力学活动的控制具有重要影响。中国联合球形托卡马克的真空容器通过一个环形绝缘屏障被分隔成两个半球形部分。因此，涡电流的特性比标准托卡马克中的更为复杂。所以，有必要测量和分析涡电流分布。在本研究中，我们提出了一种测量真空容器中涡电流分布的实验方法。通过将带有磁探针的柔性印刷电路板放置在真空容器的外表面上，以测量平行于表面的磁场，然后减去垂直场线圈产生的磁场，就可以得到涡电流产生的磁场，并确定其分布。我们成功地将该方法应用于中国联合球形托卡马克，从而在存在外部线圈产生的磁场的情况下获得了涡电流分布。
