delta f Monte Carlo calculation of neoclassical transport in perturbed tokamaks

作者：Kim Kimin^*; Park Jong Kyu; Kramer Gerrit J; Boozer Allen H

来源：Physics of Plasmas, 2012, 19(8): 082503.

DOI：10.1063/1.4740511

Non-axisymmetric magnetic perturbations can fundamentally change neoclassical transport in tokamaks by distorting particle orbits on deformed or broken flux surfaces. This so-called non-ambipolar transport is highly complex, and eventually a numerical simulation is required to achieve its precise description and understanding. A new delta f particle orbit code (POCA) has been developed for this purpose using a modified pitch-angle collision operator preserving momentum conservation. POCA was successfully benchmarked for neoclassical transport and momentum conservation in the axisymmetric configuration. Non-ambipolar particle flux is calculated in the non-axisymmetric case, and the results show a clear resonant nature of non-ambipolar transport and magnetic braking. Neoclassical toroidal viscosity (NTV) torque is calculated using anisotropic pressures and magnetic field spectrum, and compared with the combined and 1/v. NTV theory. Calculations indicate a clear delta B-2 scaling of NTV, and good agreement with the theory on NTV torque profiles and amplitudes depending on collisionality.

• 出版日期2012-8