Error field optimization in DIII-D using extremum seeking control
Abstract
A closed-loop error field control algorithm is implemented in the Plasma Control System of the DIII-D tokamak and used to identify optimal control currents during a single plasma discharge. The algorithm, based on established extremum seeking control theory, exploits the link in tokamaks between maximizing the toroidal angular momentum and minimizing deleterious non-axisymmetric magnetic fields. 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.
- Authors:
-
- General Atomics, San Diego, CA (United States)
- Oak Ridge Associated Univ., Oak Ridge, TN (United States)
- Univ. of California San Diego, La Jolla, CA (United States)
- Columbia Univ., New York, NY (United States)
- Publication Date:
- Research Org.:
- General Atomics, San Diego, CA (United States)
- Sponsoring Org.:
- USDOE
- OSTI Identifier:
- 1371745
- Alternate Identifier(s):
- OSTI ID: 1255456
- Grant/Contract Number:
- FC02-04ER54698; AC05-06OR23100; FG02-04ER54761
- Resource Type:
- Accepted Manuscript
- Journal Name:
- Nuclear Fusion
- Additional Journal Information:
- Journal Volume: 56; Journal Issue: 7; Related Information: M.J. Lanctot, K.E.J. Olofsson, M. Capella, D.A. Humphreys, N. Eidietis, J.M. Hanson, C. Paz-Soldan, E.J. Strait and M.L. Walker, "Error field optimization in DIII-D using extremum seeking control," Nucl. Fusion 56, 076003 (2016).; Journal ID: ISSN 0029-5515
- Publisher:
- IOP Science
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; error field optimization; real-time control; non-axisymmetric fields
Citation Formats
Lanctot, M. J., Olofsson, K. E. J., Capella, M., Humphreys, D. A., Eidietis, N., Hanson, J. M., Paz-Soldan, C., Strait, E. J., and Walker, M. L. Error field optimization in DIII-D using extremum seeking control. United States: N. p., 2016.
Web. doi:10.1088/0029-5515/56/7/076003.
Lanctot, M. J., Olofsson, K. E. J., Capella, M., Humphreys, D. A., Eidietis, N., Hanson, J. M., Paz-Soldan, C., Strait, E. J., & Walker, M. L. Error field optimization in DIII-D using extremum seeking control. United States. https://doi.org/10.1088/0029-5515/56/7/076003
Lanctot, M. J., Olofsson, K. E. J., Capella, M., Humphreys, D. A., Eidietis, N., Hanson, J. M., Paz-Soldan, C., Strait, E. J., and Walker, M. L. Fri .
"Error field optimization in DIII-D using extremum seeking control". United States. https://doi.org/10.1088/0029-5515/56/7/076003. https://www.osti.gov/servlets/purl/1371745.
@article{osti_1371745,
title = {Error field optimization in DIII-D using extremum seeking control},
author = {Lanctot, M. J. and Olofsson, K. E. J. and Capella, M. and Humphreys, D. A. and Eidietis, N. and Hanson, J. M. and Paz-Soldan, C. and Strait, E. J. and Walker, M. L.},
abstractNote = {A closed-loop error field control algorithm is implemented in the Plasma Control System of the DIII-D tokamak and used to identify optimal control currents during a single plasma discharge. The algorithm, based on established extremum seeking control theory, exploits the link in tokamaks between maximizing the toroidal angular momentum and minimizing deleterious non-axisymmetric magnetic fields. 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.},
doi = {10.1088/0029-5515/56/7/076003},
journal = {Nuclear Fusion},
number = 7,
volume = 56,
place = {United States},
year = {Fri Jun 03 00:00:00 EDT 2016},
month = {Fri Jun 03 00:00:00 EDT 2016}
}
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Works referenced in this record:
Locked modes in DIII-D and a method for prevention of the low density mode
journal, May 1991
- Scoville, J. T.; La Haye, R. J.; Kellman, A. G.
- Nuclear Fusion, Vol. 31, Issue 5
Analysis and correction of intrinsic non-axisymmetric magnetic fields in high- DIII-D plasmas
journal, October 2002
- Garofalo, A. M.; Haye, R. J. La; Scoville, J. T.
- Nuclear Fusion, Vol. 42, Issue 11
Resistive wall stabilized operation in rotating high beta NSTX plasmas
journal, April 2006
- Sabbagh, S. A.; Sontag, A. C.; Bialek, J. M.
- Nuclear Fusion, Vol. 46, Issue 5
Error field experiments in JET
journal, April 2000
- Buttery, R. J.; Benedetti, M. De'; Hender, T. C.
- Nuclear Fusion, Vol. 40, Issue 4
Multi-mode error field correction on the DIII-D tokamak
journal, March 2003
- Scoville, J. T.; Haye, R. J. La
- Nuclear Fusion, Vol. 43, Issue 4
Nonaxisymmetric field effects on Alcator C-Mod
journal, May 2005
- Wolfe, S. M.; Hutchinson, I. H.; Granetz, R. S.
- Physics of Plasmas, Vol. 12, Issue 5
Overview of recent physics results from the National Spherical Torus Experiment (NSTX)
journal, September 2007
- Menard, J. E.; Bell, M. G.; Bell, R. E.
- Nuclear Fusion, Vol. 47, Issue 10
Locked mode thresholds on the MAST spherical tokamak
journal, August 2007
- Howell, D. F.; Hender, T. C.; Cunningham, G.
- Nuclear Fusion, Vol. 47, Issue 9
In-vessel saddle coils for MHD control in ASDEX Upgrade
journal, June 2009
- Suttrop, W.; Gruber, O.; Günter, S.
- Fusion Engineering and Design, Vol. 84, Issue 2-6
Dynamic decoupling and multi-mode magnetic feedback for error field correction in RFX-mod
journal, May 2011
- Piron, L.; Grando, L.; Marchiori, G.
- Nuclear Fusion, Vol. 51, Issue 6
Anomalies in the applied magnetic fields in DIII-D and their implications for the understanding of stability experiments
journal, December 2003
- Luxon, J. L.; Schaffer, M. J.; Jackson, G. L.
- Nuclear Fusion, Vol. 43, Issue 12
Progress in understanding error-field physics in NSTX spherical torus plasmas
journal, March 2010
- Menard, J. E.; Bell, R. E.; Gates, D. A.
- Nuclear Fusion, Vol. 50, Issue 4
Computation of three-dimensional tokamak and spherical torus equilibria
journal, May 2007
- Park, Jong-kyu; Boozer, Allen H.; Glasser, Alan H.
- Physics of Plasmas, Vol. 14, Issue 5
Error Field Amplification and Rotation Damping in Tokamak Plasmas
journal, May 2001
- Boozer, Allen H.
- Physical Review Letters, Vol. 86, Issue 22
Control of Asymmetric Magnetic Perturbations in Tokamaks
journal, November 2007
- Park, Jong-kyu; Schaffer, Michael J.; Menard, Jonathan E.
- Physical Review Letters, Vol. 99, Issue 19
The spectral basis of optimal error field correction on DIII-D
journal, April 2014
- Paz-Soldan, C.; Buttery, R. J.; Garofalo, A. M.
- Nuclear Fusion, Vol. 54, Issue 7
A method to measure poloidal field coil irregularities in toroidal plasma devices
journal, September 1991
- La Haye, R. J.; Scoville, J. T.
- Review of Scientific Instruments, Vol. 62, Issue 9
Sustained rotational stabilization of DIII-D plasmas above the no-wall beta limit
journal, May 2002
- Garofalo, A. M.; Jensen, T. H.; Johnson, L. C.
- Physics of Plasmas, Vol. 9, Issue 5
Overview of physics results from the conclusive operation of the National Spherical Torus Experiment
journal, September 2013
- Sabbagh, S. A.; Ahn, J. -W.; Allain, J.
- Nuclear Fusion, Vol. 53, Issue 10
RFX-mod: A multi-configuration fusion facility for three-dimensional physics studies
journal, May 2013
- Piovesan, P.; Bonfiglio, D.; Auriemma, F.
- Physics of Plasmas, Vol. 20, Issue 5
Observation and correction of non-resonant error fields in NSTX
journal, September 2010
- Gerhardt, S. P.; Menard, J. E.; Park, J-K
- Plasma Physics and Controlled Fusion, Vol. 52, Issue 10
Measurement of tokamak error fields using plasma response and its applicability to ITER
journal, April 2014
- Strait, E. J.; Buttery, R. J.; Casper, T. A.
- Nuclear Fusion, Vol. 54, Issue 7
Feedback Stabilization of Multiple Resistive Wall Modes
journal, November 2004
- Brunsell, P. R.; Yadikin, D.; Gregoratto, D.
- Physical Review Letters, Vol. 93, Issue 22
Access to sustained high-beta with internal transport barrier and negative central magnetic shear in DIII-D
journal, May 2006
- Garofalo, A. M.; Doyle, E. J.; Ferron, J. R.
- Physics of Plasmas, Vol. 13, Issue 5
A simple model for driven islands in tokamaks
journal, April 1993
- Jensen, T. H.; Leonard, A. W.; Hyatt, A. W.
- Physics of Fluids B: Plasma Physics, Vol. 5, Issue 4
Bifurcated states of a rotating tokamak plasma in the presence of a static error-field
journal, September 1998
- Fitzpatrick, Richard
- Physics of Plasmas, Vol. 5, Issue 9
Error-field induced electromagnetic torques in a large aspect-ratio, low-β, weakly shaped tokamak plasma
journal, March 2009
- Fitzpatrick, Richard
- Physics of Plasmas, Vol. 16, Issue 3
Decoupled recovery of energy and momentum with correction of n = 2 error fields
journal, July 2015
- Paz-Soldan, C.; Logan, N. C.; Lanctot, M. J.
- Nuclear Fusion, Vol. 55, Issue 8
Real-Time Optimization by Extremum-Seeking Control
book, September 2003
- Ariyur, Kartik B.; Krstić, Miroslav
Characterization of cross-section correction to charge exchange recombination spectroscopy rotation measurements using co- and counter-neutral-beam views
journal, October 2008
- Solomon, W. M.; Burrell, K. H.; Feder, R.
- Review of Scientific Instruments, Vol. 79, Issue 10
Effect of resonant and non-resonant magnetic braking on error field tolerance in high beta plasmas
journal, September 2009
- Reimerdes, H.; Garofalo, A. M.; Strait, E. J.
- Nuclear Fusion, Vol. 49, Issue 11
ITER test blanket module error field simulation experiments at DIII-D
journal, September 2011
- Schaffer, M. J.; Snipes, J. A.; Gohil, P.
- Nuclear Fusion, Vol. 51, Issue 10
Overview of the ITER Correction Coils Design
journal, June 2010
- Foussat, A.; Libeyre, P.; Mitchell, N.
- IEEE Transactions on Applied Superconductivity, Vol. 20, Issue 3
Toroidal and poloidal momentum transport studies in tokamaks
journal, November 2007
- Tala, T.; Crombé, K.; de Vries, P. C.
- Plasma Physics and Controlled Fusion, Vol. 49, Issue 12B
Chapter 2: Plasma confinement and transport
journal, June 2007
- Physics), E. J. Doyle (Chair Transport; Modelling), W. A. Houlberg (Chair Confinement Da; Edge), Y. Kamada (Chair Pedestal and
- Nuclear Fusion, Vol. 47, Issue 6
Works referencing / citing this record:
Measurement of toroidal variation in conducted heat loads in locked mode induced disruptions on DIII-D
journal, October 2018
- Hollmann, E. M.; Commaux, N.; Eidietis, N. W.
- Physics of Plasmas, Vol. 25, Issue 10