Diamagnetic Effect on the Ripple-Induced Losses of Energetic Ions in a Non-Axisymmetric Tokamak Plasma

Abstract

In a tokamak plasma, energetic ion losses are increased by the toroidal field (TF) ripple, which is mainly created by the finite number of the toroidal field coils (TFCs). The plasma current alters magnetic field structures and energetic ion orbits. The diamagnetic effect caused by the poloidal plasma current (i.e., the diamagnetic current) is one of the most important finite beta effects. We investigated how the diamagnetic effect affects energetic ion losses using the magnetohydrodynamic (MHD) equilibrium calculation code VMEC and the orbit following Monte Carlo code F3D-OFMC. As a result, it was found that the weak diamagnetic effect increased the fusion alpha particle losses, while the strong diamagnetic effect reduced them.