Gyrokinetic Simulations Of An Electron Temperature Gradient Turbulence Driven Current In Tokamak Plasmas

We report the results of a gyrokinetic simulation study elucidating the characteristics of the current driven by electron temperature gradient (ETG) turbulence in toroidal geometry. We examined the amount of the ETG turbulence-driven current for different turbulence levels, which were obtained by varying the relative electron gyroradius rho* = rho(e)/a. Simulations show that the amount of the ETG turbulence-driven current increases with rho* due to the gyro-Bohm scaling of turbulence intensity. A perturbation of the equilibrium q-profile by the ETG turbulence-driven current becomes noticeable when rho* > 1/4000. Even in a small rho* case, the proportional relation between the ETG turbulence-driven current and turbulence intensity suggests that a considerable intrinsic current can be driven inside an edge pedestal where a steep gradient of the electron temperature profile can excite ETG turbulence in a narrow region. Published by AIP Publishing.