Global kinetic effect on the collisionality dependence of the neoclassical toroidal viscosity in the superbanana-plateau regime

Matsuoka, Seikichi ; Idomura, Yasuhiro   ; Satake, Shinsuke*

Effects of non-axisymmetric magnetic field perturbations have attracted much attention from the view point of the control of the plasma performance and instabilities. Recent studies pointed out that the qualitative discrepancy of the NTV prediction exist between a theoretical bounce-averaged model and a global kinetic simulation. It is crucial to clarify the cause of the discrepancy to establish a reliable basis for the NTV predictions. In this work, we perform two types of global kinetic simulations for the NTV to investigate the discrepancy from the theoretical model. As a result, it is first demonstrated that the discrepancy arises owing to the following two mechanisms; (1) resonant structures predicted in the bounce-averaged model disappear due to the large particle orbit in the global kinetic simulations, and (2) fine scale structures are generated in the velocity space in the global kinetic simulations.