Error field optimization in DIII-D using extremum seeking control

被引：15
作者：
Lanctot, M. J. [1 ]
Olofsson, K. E. J. [2 ]
Capella, M. [3 ]
Humphreys, D. A. [1 ]
Eidietis, N. [1 ]
Hanson, J. M. [4 ]
Paz-Soldan, C. [1 ]
Strait, E. J. [1 ]
Walker, M. L. [1 ]
机构：
[1] Gen Atom, POB 85608, San Diego, CA 92186 USA
[2] Oak Ridge Associated Univ, POB 117, Oak Ridge, TN 37831 USA
[3] Univ Calif San Diego, La Jolla, CA 92093 USA
[4] Columbia Univ, Dept Appl Phys & Appl Math, New York, NY 10027 USA
来源：
NUCLEAR FUSION | 2016年 / 56卷 / 07期
关键词：
error field optimization; real-time control; non-axisymmetric fields; HIGH-BETA; MAGNETIC-FIELDS; D PLASMAS; TOKAMAK; TRANSPORT; MODE; NSTX;
D O I：
10.1088/0029-5515/56/7/076003
中图分类号：
O35 [流体力学]; O53 [等离子体物理学];
学科分类号：
070204 ; 080103 ; 080704 ;
摘要：
DIII-D experiments have demonstrated a new real-time approach to tokamak error field control based on maximizing the toroidal angular momentum. This approach uses extremum seeking control theory to optimize the error field in real time without inducing instabilities. Slowly-rotating n = 1 fields (the dither), generated by external coils, are used to perturb the angular momentum, monitored in real-time using a charge-exchange spectroscopy diagnostic. Simple signal processing of the rotation measurements extracts information about the rotation gradient with respect to the control coil currents. This information is used to converge the control coil currents to a point that maximizes the toroidal angular momentum. The technique is well-suited for multi-coil, multi-harmonic error field optimizations in disruption sensitive devices as it does not require triggering locked tearing modes or plasma current disruptions. Control simulations highlight the importance of the initial search direction on the rate of the convergence, and identify future algorithm upgrades that may allow more rapid convergence that projects to convergence times in ITER on the order of tens of seconds.
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页数：12
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