Improving the stellarator through advances in plasma theory

Hegna, C. C.; Anderson, David T.; Bader, A.; Bechtel, Torrin; Bhattacharjee, A.; Cole, M.; Drevlak, M.; Duff, J. M.; Faber, B. J.; Hudson, S. R.; Kotschenreuther, M.; Krüger, Thomas; Landreman, Matt; McKinney, I. J.; Paul, Elizabeth; Pueschel, M. J.; Terry, P. W.; Ware, A. S.; Zarnstorff, M. C.; Zhu, Caoxiang

doi:10.1088/1741-4326/ac29d0

Cited by 11 publications

(8 citation statements)

References 131 publications

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“…This means that the 0D analysis also over-estimates the required on-axis magnetic field for a target fusion gain (15% overestimation of B according to Alonso et al [25]). In addition, the current study relies on scaling laws for both the energy confinement time which could be improved by the use of transport codes [31,[121][122][123]. Similarly, the cost models used in the study relies on costing power laws developed in the late 1990s and early 2000s which might not reflect the current cost of both raw materials nor services [54,55,58].…”

Section: Discussionmentioning

confidence: 99%

Economically optimized design point of high-field stellarator power-plant

Prost,

Volpe

2024

Nucl. Fusion

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High Temperature Superconductors expand the design space of stellarator power-plants toward high magnetic fields B, enabling compact major radii $R$. The present paper scans the space of B, R and other design parameters, finding solutions that are promising from a physics and engineering standpoint, while minimizing the capital cost of the power-plant and the levelized cost of fusion electricity. Similarly, it identifies minimum-cost design points for next-step burning plasma stellarator experiments of fusion gain 1 < Q < 10. The study assumes advanced stellarator configurations of reduced aspect ratio, heated by Neutral Beam Injection. Plasma-facing, flowing liquid metal walls protect it from high heat and neutron fluxes. The study relies on analytical first-principle calculations, and established zero-dimensional empirical scaling laws. Power flows are illustrated by Sankey diagrams. Plasma operating contours are used to determine the reactor’s start-up path. Sensitivity analyses are conducted to identify the most critical reactor parameters within physics, engineering and costing, quantifying their influence on the economics of the power plants. Such 0D study suggests that the assumed next generation HTS, flowing liquid metal walls, and advances in compact plasma configurations could lead to an ignited stellarator power-plant of aspect ratio A ~ 4, R ≤ 4 m, B > 9 T, and normalized plasma pressure β ~ 5 % would minimize both the cost of electricity and capital cost while achieving a net electric power of about 1 GW.

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Section: Discussionmentioning

confidence: 99%

Economically optimized design point of high-field stellarator power-plant

Prost,

Volpe

2024

Nucl. Fusion

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“…One of the most expensive and technically challenging aspects of the construction of stellarators [14,21,25] is the design, manufacturing and assembly of the primary coil system that generates the magnetic field confining the plasma. As computing resources and simulation capabilities have increased over the last few decades, large-scale numerical optimization has proven to be the method of choice for the design of new stellarator experiments [11]. Numerical simulations of guidingcenter trajectories have shown that the state-of-the-art stellarator designs obtained from these optimization efforts are * Author to whom any correspondence should be addressed.…”

Section: Introductionmentioning

confidence: 99%

Stochastic and a posteriori optimization to mitigate coil manufacturing errors in stellarator design

Wechsung¹,

Giuliani²,

Landreman³

et al. 2022

Plasma Phys. Control. Fusion

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It was recently shown in [Wechsung et. al., Proc. Natl. Acad. Sci. USA, 2022] that there exist electromagnetic coils that generate magnetic fields which are excellent approximations to quasi-symmetric fields and have very good particle confinement properties. Using a Gaussian process based model for coil perturbations, we investigate the impact of manufacturing errors on the performance of these coils. We show that even fairly small errors result in noticeable performance degradation. While stochastic optimization yields minor improvements, it is not able to mitigate these errors significantly. As an alternative to stochastic optimization, we then formulate a new optimization problem for computing optimal adjustments of the coil positions and currents without changing the shapes of the coil. These a-posteriori adjustments are able to reduce the impact of coil errors by an order of magnitude, providing a new perspective for dealing with manufacturing tolerances in stellarator design.

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“…One of the most expensive and technically challenging aspects of the construction of stellarators [14,21,24] is the design, manufacturing and assembly of the primary coil system that generates the magnetic field confining the plasma. As computing resources and simulation capabilities have increased over the last few decades, large-scale numerical optimization has proven to be the method of choice for the design of new stellarator experiments [11]. Numerical simulations of guiding-center trajectories have shown that the state-of-the-art stellarator designs obtained from these optimization efforts are now able to confine even highly energetic particles for long timescale with minimal losses -a key requirement for practical use as fusion reactors [4,7,16,26].…”

Section: Introductionmentioning

confidence: 99%

Stochastic and a posteriori optimization to mitigate coil manufacturing errors in stellarator design

Wechsung¹,

Giuliani²,

Landreman³

et al. 2022

Preprint

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It was recently shown in [Wechsung et. al., Proc. Natl. Acad. Sci. USA, 2022, to appear] that there exist electromagnetic coils that generate magnetic fields which are excellent approximations to quasi-symmetric fields and have very good particle confinement properties. Using a Gaussian process based model for coil perturbations, we investigate the impact of manufacturing errors on the performance of these coils. We show that even fairly small errors result in noticeable performance degradation and that stochastic optimization is not able to mitigate these errors significantly. We then formulate a new optimization problem for computing optimal adjustments of the coil positions and currents without changing the shapes of the coil. These a-posteriori adjustments are able to reduce the impact of coil errors by an order of magnitude, providing a new perspective for dealing with manufacturing uncertainties in stellarator design.

show abstract

Improving the stellarator through advances in plasma theory

Cited by 11 publications

References 131 publications

Economically optimized design point of high-field stellarator power-plant

Economically optimized design point of high-field stellarator power-plant

Stochastic and a posteriori optimization to mitigate coil manufacturing errors in stellarator design

Stochastic and a posteriori optimization to mitigate coil manufacturing errors in stellarator design

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