SIMSOPT: A flexible framework for stellarator optimization

Landreman, Matt; Medasani, Bharat; Wechsung, Florian; Giuliani, Andrew; Jorge, Rogério; Zhu, Caoxiang

doi:10.21105/joss.03525

Cited by 59 publications

(66 citation statements)

References 18 publications

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“…Since five surfaces might not be sufficient in all configurations, the possibility of parallelizing the surface and adjoint solves, as available in our implementation, means that we do not have to compromise on the number of surfaces used. Our implementation relies heavily on the open-source stellarator optimization package SIMSOPT (Landreman et al 2021) where many aspects of this work are contributed. We also use SIMSOPT's "optimizable" framework for efficient representation of our objective (appendix C).…”

Section: Coil Optimization For Precise Quasi-axisymmetry On Surfacesmentioning

confidence: 99%

“…The different penalty terms of the optimization problem in section 4.1 are implemented using the "optimizable" framework in SIMSOPT (Landreman et al 2021). The dependencies between the various quantities in optimization problems result in a directed acyclical graph, which can be used for efficient caching, i.e., terms are only recomputed when quantities that they depend on are changed.…”

Section: Optimizable Graph For Efficient Representation Of the Objectivementioning

confidence: 99%

“…The coil and surface parametrizations, Biot-Savart kernel, as well as the solver used to compute BoozerExact and BoozerLS surfaces were implemented in the SIMSOPT package (Landreman et al 2021), available at:…”

Section: Availability Of Code and Optimized Configurationsmentioning

confidence: 99%

“…Single-stage coil design, in which one optimizes for the geometry and currents of electromagnetic coils at the same time as the target magnetic configuration, is a promising approach for stellarator design as it considers physics goals and engineering constraints simultaneously (Giuliani et al 2020;Henneberg et al 2021;Wechsung et al 2021;Yu et al 2022). It has the potential to yield designs with coil systems that are easier to manufacture and position.…”

Section: Introductionmentioning

confidence: 99%

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Direct computation of magnetic surfaces in Boozer coordinates and coil optimization for quasi-symmetry

Giuliani,

Wechsung,

Landreman

et al. 2022

Preprint

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We propose a new method to compute magnetic surfaces that are parametrized in Boozer coordinates for vacuum magnetic fields. We also propose a measure for quasisymmetry on the computed surfaces and use it to design coils that generate a magnetic field that is quasi-symmetric on those surfaces. The rotational transform of the field and complexity measures for the coils are also controlled in the design problem. Using an adjoint approach, we are able to obtain analytic derivatives for this optimization problem, yielding an efficient gradient-based algorithm. Starting from an initial coil set that presents nested magnetic surfaces for a large fraction of the volume, our method converges rapidly to coil systems generating fields with excellent quasi-symmetry and low particle losses. In particular for low complexity coils, we are able to significantly improve the performance compared to coils obtained from the standard two-stage approach, e.g. reduce losses of fusion-produced alpha particles born at half-radius from 17.7% to 6.6%. We also demonstrate 16-coil configurations with alpha loss < 1% and neoclassical transport magnitude 3/2 eff less than approximately 5 × 10 −9 .

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Section: Coil Optimization For Precise Quasi-axisymmetry On Surfacesmentioning

confidence: 99%

Section: Optimizable Graph For Efficient Representation Of the Objectivementioning

confidence: 99%

Section: Availability Of Code and Optimized Configurationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Direct computation of magnetic surfaces in Boozer coordinates and coil optimization for quasi-symmetry

Giuliani,

Wechsung,

Landreman

et al. 2022

Preprint

Self Cite

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show abstract

“…Indeed, we leverage new capabilities of SPEC to show that the volume of magnetic surfaces in a stellarator can be maximized by optimizing the injected toroidal current profile, or the coil configuration -two experimentally relevant "knobs" 16 . For the optimization, we follow Landreman, Medasani, and Zhu 15 and use the SIMSOPT framework 17 , which in particular can construct an objective function based on Greene's residues 7 of some selected rational surfaces.…”

Section: Introductionmentioning

confidence: 99%