Effects of ion polarization and finite-β on heat transport in slab electron-temperature-gradient driven turbulence

Abstract

Effects of kinetic ions and electromagnetic fluctuations on slab electron-temperature-gradient (ETG) driven turbulence are investigated by means of gyrokinetic simulations covering scales from electron gyroradius to ion gyroradius and electron skin depth. Linear growth rates of electrostatic ETG modes are enhanced by the ion polarization at ion gyroradius scale. Nonlinear simulations show that this low-poloidal-wavenumber instability induces ion-scale eddies which cause heat transport higher than that in the adiabatic ion model. In finite-β plasma, electromagnetic fluctuations stabilize the low-wavenumber modes, and suppress the turbulent heat transport. Additionally, electromagnetic effects also weaken zonal flow generation, which slightly enhances turbulent transport than that in the electrostatic adiabatic ion model.