A gyrokinetic electron and fully kinetic ion particle simulation model for collisionless plasma dynamics

A novel new kinetic simulation model has been developed to investigate dynamics in collisionless plasmas, such as magnetic reconnection with a finite guide magnetic field. In this model, the electrons are treated as gyrokinetic (GK) particles and ions are treated as fully kinetic (FK) particles. In the GK-electron and FK-ion (GKe/FKi) particle simulation model, the rapid electron cyclotron motion is removed, while keeping finite electron Larmor radii, realistic electron-to-ion mass ratio, wave-particle interactions, and off-diagonal components of the electron pressure tensor. The model is particularly suitable for plasma dynamics with wave frequencies lower than the electron gyrofrequency, and for problems in which the wave modes ranging from Alfvén waves to lower-hybrid/whistler waves need to be handled on an equal footing. Using this model, the computation power can be significantly improved over that of the existing full-particle codes. The GKe/FKi model also provides important improvements in physics over the full particle models. It can handle physics with realistic electron-to-ion mass ratio and dynamic processes on the global Alfvén time/spatial scales. Compared with the hybrid (i.e., FK ion and fluid electron) codes, the advantage of the GKe/FKi code is that it includes the electron kinetic physics, such as wave-particle resonances and finite electron Larmor radius effects. The simulation model has been successfully benchmarked for linear waves in uniform plasmas against analytic dispersion relation. In this talk, the simulation model and its linear benchmark are presented.