Abstract Details
Abstracts
Author: Elizabeth J. Paul
Requested Type: Poster
Submitted: 2017-03-17 16:05:02
Co-authors: M. Landreman, W. Dorland, F. M. Poli, D. A. Spong, H.M. Smith
Contact Info:
University of Maryland
7315 Radcliffe Drive
College Park, MD 20740
United States
Abstract Text:
Neoclassical transport in the presence of non-axisymmetric magnetic fields causes a toroidal torque known as neoclassical toroidal viscosity (NTV). The toroidal symmetry of ITER will be broken by the finite number of toroidal field coils and by test blanket modules (TBMs). The addition of ferritic inserts (FIs) will decrease the magnitude of the toroidal field ripple. 3D magnetic equilibria in the presence of toroidal field ripple and ferromagnetic structures are calculated for an ITER steady-state scenario using the Variational Moments Equilibrium Code (VMEC). Neoclassical transport quantities in the presence of these error fields are calculated using the Stellarator Fokker-Planck Iterative Neoclassical Conservative Solver (SFINCS). These calculations fully account for Er, flux surface shaping, multiple species, magnitude of ripple, and collisionality rather than applying approximate analytic NTV formulae. As NTV is a complicated nonlinear function of Er, we study its behavior over a plausible range of Er. We estimate the toroidal flow, and hence Er, using a semi-analytic turbulent intrinsic rotation model and NUBEAM calculations of neutral beam torque. The NTV torque due to TF ripple is found to be comparable in magnitude to the turbulent and NBI torques, though their radial profiles differ. The NTV from the |n| = 18 ripple dominates that from lower n perturbations of the TBMs. With the inclusion of FIs, the magnitude of NTV torque is reduced by about 75% near the edge. We present comparisons of several models of tangential magnetic drifts on superbanana-plateau transport at small Er, and we consider the scaling of calculated NTV torque with ripple magnitude.
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