Calculation of Neoclassical Toroidal Viscosity with a Particle Simulation in the Tokamak Magnetic Breaking Experiments

Kimin Kim, et al

关键词: Monte Carlo Methods;    Magnetohydrodynamics (MHD);    Tokamaks;   

DOI  :  10.2172/1089859
RP-ID  :  PPPL-4869
PID  :  OSTI ID: 1089859

学科分类：原子、分子光学和等离子物理

美国|英语

来源: SciTech Connect

【 摘 要 】

Accurate calculation of perturbed distribution function ??f and perturbed magnetic fi eld ??B is essential to achieve prediction of non-ambipolar transport and neoclassical toroidal viscosity (NTV) in perturbed tokamaks. This paper reports a study of the NTV with a ??f particle code (POCA) and improved understanding of magnetic braking in tokamak experiments. POCA calculates the NTV by computing f with guiding-center orbit motion and using B from the ideal perturbed equilibrium code (IPEC). POCA simulations are compared with experimental estimations for NTV, which are measured from angular momentum balance (DIII-D) and toroidal rotational damping rate (NSTX). The calculation shows good agreement in total NTV torque for the DIII-D discharge, where an analytic neoclassical theory also gives a consistent result thanks to relatively large aspect-ratio and slow toroidal rotations. In NSTX discharges, where the aspect-ratio is small and the rotation is fast, the theory only gives a qualitative guide for predicting NTV. However, the POCA simulation largely improves the quantitative NTV prediction for NSTX. It is discussed that a self- consistent calculation of ?? B using general perturbed equilibria is eventually necessary since a non-ideal plasma response can change the perturbed eld and thereby the NTV torque.