Global turbulence simulation

Idomura, Yasuhiro

no journal, , 

We review the development of global full-f gyrokinetic simulation GT5D and recent simulation studies on Fugaku. Towards exascale simulations on Fugaku, a new matrix solver was developed using half precision computation, which was newly supported on A64FX, and an implicit finite difference solver for kinetic electrons was accelerated by ~3.5x compared to the conventional solver. This enabled global turbulence simulations with kinetic electrons at the real mass ratio. By using this code, the linear and saturated ohmic confinement (LOC/SOC) transition in ohmic L-mode discharges on the Tore Supra device was analyzed. The simulation reproduced the exhaust of carbon impurity ions, the change of intrinsic plasma rotation, and the change of energy confinement time, which are observed during the LOC/SOC transition, and their physical mechanisms were clarified.