Berzak L, Jones A D, Kaita R, Kozub T, Logan N, Majeski R, Menard J, Zakharov L
Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, New Jersey 08543, USA.
Rev Sci Instrum. 2010 Oct;81(10):10E114. doi: 10.1063/1.3484488.
The lithium tokamak experiment (LTX) is a modest-sized spherical tokamak (R(0)=0.4 m and a=0.26 m) designed to investigate the low-recycling lithium wall operating regime for magnetically confined plasmas. LTX will reach this regime through a lithium-coated shell internal to the vacuum vessel, conformal to the plasma last-closed-flux surface, and heated to 300-400 °C. This structure is highly conductive and not axisymmetric. The three-dimensional nature of the shell causes the eddy currents and magnetic fields to be three-dimensional as well. In order to analyze the plasma equilibrium in the presence of three-dimensional eddy currents, an extensive array of unique magnetic diagnostics has been implemented. Sensors are designed to survive high temperatures and incidental contact with lithium and provide data on toroidal asymmetries as well as full coverage of the poloidal cross-section. The magnetic array has been utilized to determine the effects of nonaxisymmetric eddy currents and to model the start-up phase of LTX. Measurements from the magnetic array, coupled with two-dimensional field component modeling, have allowed a suitable field null and initial plasma current to be produced. For full magnetic reconstructions, a three-dimensional electromagnetic model of the vacuum vessel and shell is under development.
锂托卡马克实验（LTX）是一个中等规模的球形托卡马克装置（R(0)=0.4米，a=0.26米），旨在研究磁约束等离子体的低再循环锂壁运行模式。LTX将通过真空容器内部的锂涂层壳层达到这种运行模式，该壳层与等离子体的最后封闭磁通表面共形，并加热到300 - 400°C。这种结构具有高导电性且不对称。壳层的三维特性导致涡流和磁场也具有三维特性。为了分析存在三维涡流时的等离子体平衡，已实施了一系列独特的磁诊断方法。传感器设计用于在高温下以及与锂的偶然接触中存活，并提供关于环形不对称性的数据以及极向横截面的全面覆盖。磁阵列已被用于确定非轴对称涡流的影响并对LTX的启动阶段进行建模。来自磁阵列的测量结果与二维场分量建模相结合，使得能够产生合适的场零点和初始等离子体电流。为了进行完整的磁重构，正在开发真空容器和壳层的三维电磁模型。
