Gyrokinetic Simulation of Turbulence in the High-β N Discharge on the Experimental Advanced Superconducting Tokamak

Experiments on Experimental Advanced Superconducting Tokamak (EAST) were performed with high normalized beta ( $${{\beta }_{N}}\sim 1.9$$ ) and favorable energy confinement ( $${{H}_{{98,y2}}}\sim 1.1$$ ) for the operating space achieved in EAST. Gyrokinetic simulations were carried out for four different $${{\beta }_{N}}$$ cases with the experimental plasma parameters and tokamak equilibrium data. It was found that the favorable confinement is effectively maintained when $${{\beta }_{N}}$$ increases to 1.9. The radial distribution of potential fluctuation during turbulence saturation phase is consistent with that of thermal transport diffusivity. Turbulence with higher toroidal modes becomes important as $${{\beta }_{N}}$$ increases, and zonal flow shearing rate suppresses the turbulence when $${{\beta }_{N}}$$ increases to 1.9, which is responsible for the well-maintained confinement.