Improved performance of stellarator coil design optimization
Abstract
Following up on earlier work which demonstrated an improved numerical stellarator coil design optimization performance by the use of stochastic optimization (Lobsien et al., Nucl. Fusion, vol. 58 (10), 2018, 106013), it is demonstrated here that significant further improvements can be made – lower field errors and improved robustness – for a Wendelstein 7-X test case. This is done by increasing the sample size and applying fully three-dimensional perturbations, but most importantly, by changing the design sequence in which the optimization targets are applied: optimization for field error is conducted first, with coil shape penalties only added to the objective function at a later step in the design process. A robust, feasible coil configuration with a local maximum field error of 3.66 % and an average field error of 0.95 % is achieved here, as compared to a maximum local field error of 6.08 % and average field error of 1.56 % found in our earlier work. These new results are compared to those found without stochastic optimization using the FOCUS and ONSET suites. The relationship between local minima in the optimization space and coil shape penalties is also discussed.
- Authors:
-
[1];
[1];
[3];
- Max Planck Society, Garching (Germany). Max Planck Institute for Plasma Physics
- Univ. of Wisconsin, Madison, WI (United States)
- Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
- Publication Date:
- Research Org.:
- Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
- Sponsoring Org.:
- USDOE
- Contributing Org.:
- This work has been carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom research and training programs 2014–2018 and 2019–2020 under grant agreement no. 633053.
- OSTI Identifier:
- 1615630
- Grant/Contract Number:
- AC02-09CH11466
- Resource Type:
- Accepted Manuscript
- Journal Name:
- Journal of Plasma Physics
- Additional Journal Information:
- Journal Volume: 86; Journal Issue: 2; Journal ID: ISSN 0022-3778
- Publisher:
- Cambridge University Press
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 70 PLASMA PHYSICS AND FUSION TECHNOLOGY
Citation Formats
Lobsien, Jim-Felix, Drevlak, Michael, Kruger, Thomas, Lazerson, Samuel, Zhu, Caoxiang, and Pedersen, Thomas Sunn. Improved performance of stellarator coil design optimization. United States: N. p., 2020.
Web. doi:10.1017/S0022377820000227.
Lobsien, Jim-Felix, Drevlak, Michael, Kruger, Thomas, Lazerson, Samuel, Zhu, Caoxiang, & Pedersen, Thomas Sunn. Improved performance of stellarator coil design optimization. United States. https://doi.org/10.1017/S0022377820000227
Lobsien, Jim-Felix, Drevlak, Michael, Kruger, Thomas, Lazerson, Samuel, Zhu, Caoxiang, and Pedersen, Thomas Sunn. Wed .
"Improved performance of stellarator coil design optimization". United States. https://doi.org/10.1017/S0022377820000227. https://www.osti.gov/servlets/purl/1615630.
@article{osti_1615630,
title = {Improved performance of stellarator coil design optimization},
author = {Lobsien, Jim-Felix and Drevlak, Michael and Kruger, Thomas and Lazerson, Samuel and Zhu, Caoxiang and Pedersen, Thomas Sunn},
abstractNote = {Following up on earlier work which demonstrated an improved numerical stellarator coil design optimization performance by the use of stochastic optimization (Lobsien et al., Nucl. Fusion, vol. 58 (10), 2018, 106013), it is demonstrated here that significant further improvements can be made – lower field errors and improved robustness – for a Wendelstein 7-X test case. This is done by increasing the sample size and applying fully three-dimensional perturbations, but most importantly, by changing the design sequence in which the optimization targets are applied: optimization for field error is conducted first, with coil shape penalties only added to the objective function at a later step in the design process. A robust, feasible coil configuration with a local maximum field error of 3.66 % and an average field error of 0.95 % is achieved here, as compared to a maximum local field error of 6.08 % and average field error of 1.56 % found in our earlier work. These new results are compared to those found without stochastic optimization using the FOCUS and ONSET suites. The relationship between local minima in the optimization space and coil shape penalties is also discussed.},
doi = {10.1017/S0022377820000227},
journal = {Journal of Plasma Physics},
number = 2,
volume = 86,
place = {United States},
year = {Wed Apr 01 00:00:00 EDT 2020},
month = {Wed Apr 01 00:00:00 EDT 2020}
}
Free Publicly Available Full Text
Publisher's Version of Record
Other availability
Search WorldCat to find libraries that may hold this journal
Cited by: 7 works
Citation information provided by
Web of Science
Web of Science
Save to My Library
You must Sign In or Create an Account in order to save documents to your library.
Works referenced in this record:
PRAXIS: Brent’s algorithm for function minimization
journal, December 1992
- Gegenfurtner, Karl R.
- Behavior Research Methods, Instruments, & Computers, Vol. 24, Issue 4
Global ideal magnetohydrodynamic stability analysis for the configurational space of Wendelstein 7–X
journal, June 1996
- Nührenberg, Carolin
- Physics of Plasmas, Vol. 3, Issue 6
Two‐Dimensional Measure‐Preserving Mappings
journal, May 1968
- Greene, John M.
- Journal of Mathematical Physics, Vol. 9, Issue 5
Hessian matrix approach for determining error field sensitivity to coil deviations
journal, April 2018
- Zhu, Caoxiang; Hudson, Stuart R.; Lazerson, Samuel A.
- Plasma Physics and Controlled Fusion, Vol. 60, Issue 5
Designing Coils for Compact Stellarators
journal, March 2002
- Strickler, Dennis J.; Berry, Lee A.; Hirshman, Steven P.
- Fusion Science and Technology, Vol. 41, Issue 2
Automated Optimization of Stellarator Coils
journal, March 1998
- Drevlak, Michael
- Fusion Technology, Vol. 33, Issue 2
Steepest-descent moment method for three-dimensional magnetohydrodynamic equilibria
journal, January 1983
- Hirshman, S. P.
- Physics of Fluids, Vol. 26, Issue 12
Stellarator coil optimization towards higher engineering tolerances
journal, August 2018
- Lobsien, Jim-Felix; Drevlak, Michael; Sunn Pedersen, Thomas
- Nuclear Fusion, Vol. 58, Issue 10
Quasi-helically symmetric toroidal stellarators
journal, May 1988
- Nührenberg, J.; Zille, R.
- Physics Letters A, Vol. 129, Issue 2
Solution of stellarator boundary value problems with external currents
journal, May 1987
- Merkel, P.
- Nuclear Fusion, Vol. 27, Issue 5
Physics analysis of results of stochastic and classic stellarator coil optimization
journal, February 2020
- Lobsien, Jim-Felix; Drevlak, Michael; Jenko, Frank
- Nuclear Fusion, Vol. 60, Issue 4
Designing stellarator coils by a modified Newton method using FOCUS
journal, April 2018
- Zhu, Caoxiang; Hudson, Stuart R.; Song, Yuntao
- Plasma Physics and Controlled Fusion, Vol. 60, Issue 6
An improved current potential method for fast computation of stellarator coil shapes
journal, February 2017
- Landreman, Matt
- Nuclear Fusion, Vol. 57, Issue 4