Effects of rotating magnetic island on the transport of trapped fast ions
Effects of rotating magnetic island on the transport of trapped fast ions
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DOI：
10.1063/5.0089582
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发表时间：
2022-08
影响因子：
2.2
通讯作者：
Jianhua Zhao;Jinjia Cao;Dong Xiang;Y. Dai;Junhui Yang;Wenjun Yang
中科院分区：
文献类型：
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作者：
Jianhua Zhao;Jinjia Cao;Dong Xiang;Y. Dai;Junhui Yang;Wenjun Yang
在漂移动力学框架下，研究了被捕获的高能离子（TEIs）在被捕获的快速离子与旋转磁岛之间的共振相互作用下的增强输运。建立了岛状旋转、捕获快速离子的弹跳运动及其进动频率（极向进动和螺旋方向进动）之间的共振方程。对于不同模数的相空间共振存在两种解，其中只有一种解具有低能量谐振线（<100 keV）；另一种既有低能谐振谱线，又有高能谱线（≥100 keV）。岛屿旋转在低能区起着重要的作用，特别是在被困通过边界附近。当共振发生在高能区域时，进动频率更为重要。因此，岛屿对低能区TEI输运的影响是本文研究的重点。得到了由碰撞、共振和孤岛引起的对称破缺引起的输运通量。我们将输运通量分为两种类型：由磁漂移引起的[公式：见文]和由岛屿旋转引起的[公式：见文]。在[公式：见文]中，在岛屿分离矩阵附近存在一个不连续性，岛屿宽度不同。在有理面（m = 2, n = 1）的右侧，[公式：见文]比[公式：见文]更重要，在等离子体边界，由于漂移引起的通量可以抑制[公式：见文]，使快速离子向等离子体内部移动。在有理曲面的左侧，[公式：见文本]占主导地位。当岛屿宽度大于某一阈值时，通量振荡，且[公式：见文]远大于[公式：见文]。
The enhanced transport of trapped energetic ions (TEIs) in the presence of resonant interactions between trapped fast ions and a rotating magnetic island is investigated within a drift-kinetic framework. Gyro-orbit banana center model equations of resonances between the island rotation, the bounce motion of trapped fast ions, and their precession frequency (poloidal precession and precession in the helical direction) are constructed. There are two solutions for resonances in phase space for different mode numbers, with only one solution having low-energy resonant lines (<100 keV); the other has not only low-energy resonant lines but also high-energy lines (≥100 keV). Island rotation plays an important role in the low-energy region, especially near the trapped-passing boundary. The precession frequency is more important when resonances occur in the high-energy area. Thus, the effect of islands on TEI transport in a low-energy region is the focus of this paper. Transport fluxes caused by collisions, resonances, and symmetry breaking induced by an island are obtained. We divide transport fluxes into two types: [Formula: see text] arising from magnetic drift and [Formula: see text] arising from the island rotation. There is a discontinuity in [Formula: see text] with different island widths near the island separatrix. On the right-hand side of the (m = 2, n = 1) rational surface, [Formula: see text] is more important than [Formula: see text], and at the plasma boundary, the flux due to drift can suppress [Formula: see text], which makes fast ions move toward inner plasma. On the left-hand side of the rational surface, [Formula: see text] is dominant. When the island width is larger than a certain threshold, the fluxes oscillate, and [Formula: see text] is far larger than [Formula: see text].