Neoclassical transport benchmark of global full-f gyrokinetic simulation in stellarator configurations

Abstract

A global full-f gyrokinetic simulation code, GT5D, is extended to incorporate stellarator equilibria, provided by a widely used three-dimensional equilibrium code, VMEC [S. P. Hirshman and O. Betancourt, J. Comput. Phys. 96, 99 (1991)]. An interface code is newly developed, in which the so-called VMEC coordinates are transformed into the coordinates of GT5D. The following benchmark calculations in a typical LHD equilibrium are carried out for the numerical verification of GT5D in stellarator configurations. First, zonal flow damping tests are performed, and good agreement in the residual levels with an analytical theory is confirmed. Second, the neoclassical transport and the ambipolar radial electric field computed by a global δf neoclassical transport code, FORTEC-3D [S. Satake et al., Plasma Fusion Res. 3, S1062 (2008)], are successfully reproduced.