Transport properties of finite-β microturbulence

Via nonlinear gyrokinetic simulations, microturbulent transport is investigated for electromagnetic trapped electron mode (TEM) and ion temperature gradient (ITG) tokamak core turbulence with p up to and beyond the kinetic ballooning mode threshold. Deviations from linear expectations are explained by zonal flow activity in the TEM case. For the ITG scenario, beta-induced changes are observed in the nonlinear critical gradient upshift from a certain p, a strong increase is observed in the Dimits shift. Additionally, a Rechester-Rosenbluth-type model for magnetic transport is applied, and the amplitudes of magnetic field fluctuations are quantified for different types of turbulence. (C) 2010 American Institute of Physics. [doi:10.1063/1.3435280]