Gyrokinetic turbulence simulations at high plasma beta

Abstract

Electromagnetic gyrokinetic turbulence simulations employing Cyclone Base Case parameters are presented for β values up to and beyond the kinetic ballooning threshold. The β scaling of the turbulent transport is found to be linked to a complex interplay of linear and nonlinear effects. Linear investigation of the kinetic ballooning mode is performed in detail, while nonlinearly, it is found to dominate the turbulence only in a fairly narrow range of β values just below the respective ideal limit. The magnetic transport scales like β2 and is well described by a Rechester–Rosenbluth-type ansatz.