标题： 规范坐标下一般环形场导向中心方程的辛积分 显示英文标题

标题： Symplectic integration of guiding-center equations in canonical coordinates for general toroidal fields

摘要： 用于环形磁场中等离子体粒子的引导中心模型的保积分对称积分方法被引入。 从圆柱坐标和通量类似坐标到规范坐标的高效变换被讨论并应用，使用磁矢势的一个分量作为空间坐标。 这种选择在理论和数值发展方面都是高效的，并且是对磁通量坐标的推广。 该变换使得可以在规范坐标中应用传统的对称积分方案以及在引导中心系统上的变分积分方法，而无需磁通量坐标。 在具有磁岛和随机区域的扰动托卡马克场中，展示了隐式中点方案的对称性质和优于传统非对称方法的优越效率。 所呈现的结果标志着向守恒物理不变量的回旋动力学模型迈出的关键一步。 显示英文摘要

摘要： Symplectic integrators with long-term preservation of integrals of motion are introduced for the guiding-center model of plasma particles in toroidal magnetic fields of general topology. An efficient transformation to canonical coordinates from cylindrical and flux-like coordinates is discussed and applied using one component of the magnetic vector potential as a spatial coordinate. This choice is efficient in both, theoretical and numerical developments and marks a generalization of magnetic flux coordinates. The transformation enables the application of conventional symplectic integration schemes formulated in canonical coordinates, as well as variational integrators on the guiding-center system, without requiring magnetic flux coordinates. Symplectic properties and superior efficiency of the implicit midpoint scheme compared to conventional non-symplectic methods are demonstrated on perturbed tokamak fields with magnetic islands and stochastic regions. The presented results mark a crucial step towards gyrokinetic models that conserve physical invariants.