In the Earth's inner magnetosphere, charged particles can be accelerated and transported by ultralow frequency (ULF) waves via drift resonance. We investigate the effects of magnetospheric convection on the nonlinear drift resonance process, which provides an inhomogeneity factor S to externally drive the pendulum equation that describes the particle motion in the ULF wave field. The S factor, defined as the ratio of the driving amplitude to the square of the pendulum trapping frequency, is found to vary with magnetic local time and, as a consequence, oscillates quasi‐periodically at the particle drift frequency ω _d . To better understand the particle behavior governed by the driven pendulum equation, we carry out simulations to obtain the evolution of electron distribution functions in energy and L‐shell phase space. We find that resonant electrons can remain phase trapped by the low‐m ULF waves under strong convection electric field, whereas for high‐m ULF waves, the electrons trajectories can be significantly modified. More interestingly, the electron drift frequency ω _d is close to the nonlinear trapping frequency ω _{t r} for intermediate‐m ULF waves, which corresponds to chaotic motion of resonant electrons. These findings shed new light on the nature of coherent and diffusive particle transport in the inner magnetosphere.

中文翻译：

---

磁层对流对电子与ULF波之间非线性漂移共振的作用

在地球的内部磁层中，带电粒子可以通过漂移共振通过超低频（ULF）波加速和传输。我们研究了磁层对流对非线性漂移共振过程的影响，该过程提供了不均匀性因子S，以外部驱动描述在ULF波场中的粒子运动的摆方程。该小号因子，定义为驱动振幅摆捕捉频率的平方的比率，被发现与磁性本地时间变化，并且作为结果，振荡准周期性在颗粒漂移频率ω _d。为了更好地理解由驱动摆方程控制的粒子行为，我们进行了模拟以获得能量和L壳相空间中电子分布函数的演化。我们发现，在强对流电场下，共振电子可以保持被低m ULF波捕获的相位，而对于高m ULF波，电子轨迹可以被显着改变。更有趣的是，电子漂移频率ω _d接近非线性捕获频率ω_{吨- [R}为中程米ULF波，它对应于共振电子的混沌运动。这些发现为内部磁层中相干和扩散粒子传输的性质提供了新的思路。