Turbulent transport due to kinetic ballooning modes in high-beta toroidal plasmas

Turbulent transport due to kinetic ballooning modes (KBMs) in high-beta toroidal plasmas is investigated by means of an electromagnetic gyrokinetic model and a newly developed electromagnetic hybrid model consisting of the gyrokinetic equation for ions and fluid equations for electrons. Full gyrokinetic simulation results for Cyclone base case tokamak with β = 2% and ηe = 0 are quickly and accurately reproduced by the hybrid simulation. Agreement between the hybrid and full kinetic simulations is confirmed on detailed transport mechanisms: electrostatic heat and particle fluxes and electromagnetic heat and particle pinches for ions and electrons. The numerical solutions satisfy the entropy balance equation, and entropy variable is transferred from ions to electrons through electromagnetic perturbation. The hybrid model enables us to simulate KBM turbulence in high-beta Large Helical Device (LHD) plasmas, for which full gyrokinetic simulation is difficult because of large computational cost. The critical beta of KBM in the standard LHD plasma is about 1.5% (1%) for ηe = 0 (ηe = 3). (author)