The problem of the collisional evolution of fast-ion guiding centre orbits inmagnetically confined plasmas is analysed in great detail. Regimes where theradial excursion of a particle orbit from a given magnetic surface is largecompared with its minimum distance from the magnetic axis are specificallyaddressed. These non-standard orbits give rise to new interesting effects. Forinstance, the time scale for precessional and bounce motions becomecomparable, which may have important consequences for plasma stability. Inwardorbit drifts and diamagnetic current effects are amplified in the non-standardorbit regime. The neo-classical bootstrap current does not vanish on themagnetic axis, opening the possibility of entirely non-inductive tokamakoperation. Non-standard fast ion orbits could also significantly affect thepower deposition profile of waves in the ion cyclotron range of frequencieslaunched into the plasma for heating purposes. The analysis in this paper isbased on a combination of analytical and numerical methods for the solution ofthe relevant Hamiltonian dynamical system and associated Fokker-Planckequation.
磁约束等离子体中快离子轨道的碰撞演化问题被详细分析。特别关注粒子轨道相对于给定磁面的径向偏移远大于其距磁轴最小距离的情形。这些非标准轨道产生了新的有趣效应。例如，进动运动与反弹运动的时间尺度变得可比，这可能对等离子体稳定性产生重要影响。在非标准轨道区域，向内漂移和抗磁电流效应被放大。新经典自举电流在磁轴附近并不消失，从而为完全非感应托卡马克运行提供了可能性。非标准快离子轨道还可能显著影响用于加热的离子回旋频率范围内波的能量沉积分布。本文的分析基于解析与数值方法相结合，用于求解相关的哈密顿系统及相应的福克-普朗克方程。