Electromagnetic gyrokinetic simulations

A new electromagnetic kinetic electron $δf$ particle simulation model has been demonstrated to work well at large values of plasma β times the ion-to-electron mass ratio [Y. Chen and S. E. Parker, J. Comput. Phys. 198, 463 (2003)]. The simulation is three-dimensional using toroidal flux-tube geometry and includes electron-ion collisions. The model shows accurate shear Alfvén wave damping and microtearing physics. Zonal flows with kinetic electrons are found to be turbulent with the spectrum peaking at zero and having a width in the frequency range of the driving turbulence. This is in contrast with adiabatic electron cases where the zonal flows are near stationary, even though the linear behavior of the zonal flow is not significantly affected by kinetic electrons. Zonal fields are found to be very weak, consistent with theoretical predictions for β below the kinetic ballooning limit. Detailed spectral analysis of the turbulence data is presented in the various limits.