Guiding center and gyrokinetic orbit theory for large electric field gradients and strong shear flows

I. Joseph
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引用次数: 4

Abstract

The guiding center and gyrokinetic theory of magnetized particle motion is extended to the regime of large electric field gradients perpendicular to the magnetic field. A gradient in the electric field directly modifies the oscillation frequency and causes the Larmor orbits to deform from circular to elliptical trajectories. In order to retain a good adiabatic invariant, there can only be strong dependence on a single coordinate at lowest order, so that resonances do not generate chaotic motion that destroys the invariant. When the gradient across magnetic flux surfaces is dominant, the guiding center drift velocity becomes anisotropic in response to external forces and additional curvature drifts must be included. The electric polarization density remains gyrotropic, but both the polarization and magnetization are modified by the change in gyrofrequency. The theory can be applied to strong shear flows, such as are commonly observed in the edge transport barrier of a high-performance tokamak (H-mode) pedestal, even if the toroidal/guide field is small. Yet, the theory retains a mathematical form that is similar to the standard case and can readily be implemented within existing simulation tools.
大电场梯度和强剪切流的导向中心和陀螺动力学轨道理论
将磁化粒子运动的导向中心和陀螺动力学理论推广到与磁场垂直的大电场梯度领域。电场中的梯度直接改变了振荡频率,导致拉莫尔轨道由圆形轨迹变形为椭圆轨迹。为了保持良好的绝热不变量,只能在最低阶上对单个坐标有很强的依赖性,这样共振就不会产生破坏不变量的混沌运动。当磁通面梯度占主导地位时,导向中心漂移速度对外力的响应成为各向异性,必须包含附加曲率漂移。电极化密度保持回转性,但极化强度和磁化强度随回转率的变化而变化。该理论可以应用于强剪切流,例如在高性能托卡马克(h模)基座的边缘传输障壁中常见的剪切流,即使环面/导向场很小。然而,该理论保留了与标准情况类似的数学形式,可以很容易地在现有的仿真工具中实现。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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