Numerical optimization of three-dimensional coils for NSTX-U
Authors: S.A. Lazerson, J-K. Park, N. Logan, A.
Boozer
Abstract: A tool for the calculation of optimal
three-dimensional (3D) perturbative magnetic fields in tokamaks
has been developed. The IPECOPT code builds upon the stellarator
optimization code STELLOPT to allow for optimization of linear
ideal magnetohydrodynamic perturbed equilibrium (IPEC). This tool
has been applied to NSTX-U equilibria, addressing which fields
are the most e ffective at driving NTV torques. The NTV torque
calculation is performed by the PENT code. Optimization of the
normal field spectrum shows that fields with n = 1
character can drive a large core torque. It is also shown that
fields with n = 3 features are capable of driving edge
torque, and some core torque. Coil current optimization (using the
planned in-vessel and existing RWM coils) on NSTX-U suggest the
planned coils set is adequate for core and edge torque control.
Comparison between error fi eld correction experiments on DIII-D
and the optimizer show good agreement.
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Submitted to: Plasma Physics and Controlled
Fusion
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