Test particle simulation

Simulation of high energy particle dynamics in the inner magnetosphere: Variational symplectic algorithm

Charged particle dynamics in magnetosphere has temporal and spatial multi-scale; therefore, numerical accuracy over a long integration time is required. A variational symplectic integrator (VSI) for the guiding-center motion of charged particles in general magnetic field is applied to study the dynamics of charged particles in magnetosphere. The VSI conserves exactly a discrete Lagrangian symplectic structure and has better numerical properties over a long integration time, compared with fourth order Runge-Kutta methods. Applying the VSI method to particle dynamics in the inner magnetosphere, we can accurately calculate the particles’ orbits for an long time with good conservation property.

Reference: Li et al., (2011), Variational symplectic algorithm for guiding center dynamics in the inner magnetosphere, Physics of Plasmas, https://doi.org/10.1063/1.3589275

Nonlinear phase trapping simulation using test particle simulations

Test particle simulation is a useful method for studying both linear and nonlinear wave-particle interactions in the magnetosphere. We show that the wave centripetal force, which was considered small and was neglect in previous studies of nonlinear interactions, has a profound time derivative and can significantly enhance electron phase trapping. This force can also bounce the low pitch angle particles out of the loss cone.

Reference: Li et al., (2015), Comparison of formulas for resonant interactions between energetic electrons and oblique whistler-mode waves, Physical of Plasmas, https://doi.org/10.1063/1.4914852