Study of in-vessel nonaxisymmetric ELM suppression coil concepts for ITER
Study of in-vessel nonaxisymmetric ELM suppression coil concepts for ITER
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DOI：
10.1088/0029-5515/48/2/024004
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发表时间：
2008-02
期刊：
影响因子：
3.3
通讯作者：
M. Schaffer;J. Menard;M. Aldan;J. Bialek;T. Evans;R. Moyer
中科院分区：
文献类型：
--
作者：
M. Schaffer;J. Menard;M. Aldan;J. Bialek;T. Evans;R. Moyer
大的I型边缘局域模（ELM）热脉冲可能会限制燃烧等离子体中偏滤器靶的寿命。最近的实验表明，俯仰共振的非轴对称磁扰动的等离子体边缘的0.0005或更少的主磁场提供了一个有用的解决方案，但在目前设计的ITER空间很小，即使是小扰动线圈。我们提出了ITER ELM抑制线圈的要求，主要来自DIII-D ELM抑制实验。我们通过计算的例子表明，大阵列的线圈，（例如，四个环形排，每个排九个线圈）在等离子体附近的外侧壁上（在包层-真空容器界面半径R = 8 m处）可以满足已知的要求，用环形螺旋傅立叶谐波谱表示，对于低q和高q ITER等离子体，当线圈电流被分配以将磁扰动集中到单个主傅立叶谱峰时。来自少于四行九个线圈的阵列的场（a）相对更强地穿透到核心等离子体中，并且（B）产生更多和更大的非共振谱峰。预期这两个特征将制动所需的等离子体旋转。我们发现，从近似正弦扰动有限的离散线圈组的莫尔效应可以用来控制非基波谐波在大型阵列。我们表明，一个明智的选择线圈之间的电流分布改善了80°环形间隙的影响，没有线圈被允许在ITER中平面。
Large Type-I edge-localized mode (ELM) heat pulses may limit the life of divertor targets in a burning plasma. Recent experiments show that pitch-resonant nonaxisymmetric magnetic perturbations of the plasma edge of 0.0005 or less of the main magnetic field offer a useful solution, but there is little room in the presently designed ITER for even small perturbation coils. We present proposed coil requirements for ITER ELM suppression, derived primarily from DIII-D ELM suppression experiments. We show by calculated examples that large arrays of coils (e.g. four toroidal rows of nine coils each) on the outboard wall near the plasma (at the radius of the blanket-vacuum vessel interface R ∼ 8 m) can meet the known requirements, expressed in terms of the toroidal helical Fourier harmonic spectrum, for both low- and high-q ITER plasmas, when coil currents are distributed to concentrate the magnetic perturbation into a single dominant Fourier spectral peak. Fields from arrays of less than four rows of nine coils (a) penetrate relatively more strongly into the core plasma, and (b) generate more and larger nonresonant spectral peaks. Both features are expected to brake desirable plasma rotation. We found that the Moiré effect from approximating sinusoidal perturbations by a limited discrete coil set can be used to control nonfundamental harmonics in large arrays. We show that a judicious choice of current distribution among the coils ameliorates effects of an 80° toroidal gap where no coils are allowed in the ITER midplane.