Stellarator Research Opportunities: A Report of the National Stellarator Coordinating Committee

Gates, D.; Anderson, David T.; Anderson, Simon; Zarnstorff, M. C.; Spong, D. A.; Weitzner, Harold; Neilson, G.H.; Ruzic, D. N.; Andruczyk, Daniel; Harris, J. H.; Mynick, H.; Hegna, C. C.; Schmitz, O.; Talmadge, J. N.; Curreli, Davide; Maurer, D.A.; Boozer, Allen H.; Knowlton, S.; Allain, Jean Paul; Ennis, D.A.; Wurden, G. A.; Reiman, A.; Lore, J.; Landreman, Matt; Freidberg, Jeffrey P.; Hudson, S. R.; Porkoláb, M.; Demers, D. R.; Terry, J.; Edlund, E.; Lazerson, S.; Pablant, N.; Fonck, R. J.; Volpe, F.; Canik, J.; Granetz, R.; Ware, A. S.; Hanson, J.D.; Kumar, S. T. A.; Deng, C.; Likin, K. M.; Cerfon, Antoine; Ram, A. K.; Hassam, A. B.; Prager, S. C.; Paz-Soldan, C.; Pueschel, M. J.; Joseph, I.; Glasser, A.

doi:10.1007/s10894-018-0152-7

Cited by 19 publications

(14 citation statements)

References 108 publications

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“…Investigating alpha particle instabilities will be important for reactors. For an overview of current research on energetic particle modes in stellarators, and the possibility of achieving reduced mode drive due to operation at higher density, see § 2.5 of Gates et al (2018).…”

Section: Resultsmentioning

confidence: 99%

Stellarator equilibria with reactor relevant energetic particle losses

et al. 2019

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Stellarator configurations with reactor relevant energetic particle losses are constructed by simultaneously optimizing for quasisymmetry and an analytically derived metric ( $\unicode[STIX]{x1D6E4}_{c}$ ), which attempts to align contours of the second adiabatic invariant, $J_{\Vert }$ with magnetic surfaces. Results show that with this optimization scheme it is possible to generate quasihelically symmetric equilibria on the scale of ARIES-CS which completely eliminate all collisionless alpha particle losses within normalized radius $r/a=0.3$ . We show that the best performance is obtained by reducing losses at the trapped–passing boundary. Energetic particle transport can be improved even when neoclassical transport, as calculated using the metric $\unicode[STIX]{x1D716}_{\text{eff}}$ , is degraded. Several quasihelically symmetric equilibria with different aspect ratios are presented, all with excellent energetic particle confinement.

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Section: Resultsmentioning

confidence: 99%

Stellarator equilibria with reactor relevant energetic particle losses

et al. 2019

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“…Stellarators possess inherent advantages that are important to consider for future fusion power plant designs, including steady-state operation, resiliency to disruptions and theoretically high beta stability limits (Gates et al 2018). Although stellarators have desirable physics properties, they also require complicated engineering.…”

Section: Introductionmentioning

confidence: 99%

Constrained stellarator coil curvature optimization with FOCUS

et al. 2021

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Finding less complicated coils that have adequately low field errors is a crucial step in stellarator development. One coil metric that is of high importance is the maximum curvature of the coil centreline, or coil single filament. Conductors cannot be bent below some threshold minimum radius of curvature. High coil curvatures can cause strains to exceed acceptable levels, especially in superconducting coils. We investigate three ways to optimize coil curvature and find that applying penalty functions to the coil curvature solves for coils that have a constrained maximum curvature and low field error. Penalty functions are implemented in FOCUS and coil solutions optimized for an HSX-like ‘plasma boundary’ are presented.

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“…The stellarator is an appealing fusion reactor concept because plasma discharges are disruption-free in the absence of large plasma currents and steady-state operation is possible (Gates et al. 2018). However, the classical stellarator exhibits poor neoclassical transport properties at low collisionality, a by-product of poorly-confined trapped-particle orbits.…”

Section: Introductionmentioning

confidence: 99%

A comparison of turbulent transport in a quasi-helical and a quasi-axisymmetric stellarator

et al. 2019

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Ion-temperature-gradient-driven (ITG) turbulence is compared for two quasi-symmetric (QS) stellarator configurations to determine the relationship between linear growth rates and nonlinear heat fluxes. We focus on the quasi-helically symmetric (QHS) stellarator HSX and the quasi-axisymmetric (QAS) stellarator NCSX. In normalized units, HSX exhibits higher growth rates than NCSX, while heat fluxes in gyro-Bohm units are lower in HSX. These results hold for simulations made with both adiabatic and kinetic electrons. The results show that HSX has a larger number of subdominant modes than NCSX and that eigenmodes are more spatially extended in HSX. We conclude that the consideration of nonlinear physics is necessary to accurately assess the heat flux due to ITG turbulence when comparing QS stellarator equilibria.

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Stellarator Research Opportunities: A Report of the National Stellarator Coordinating Committee

Cited by 19 publications

References 108 publications

Stellarator equilibria with reactor relevant energetic particle losses

Stellarator equilibria with reactor relevant energetic particle losses

Constrained stellarator coil curvature optimization with FOCUS

A comparison of turbulent transport in a quasi-helical and a quasi-axisymmetric stellarator

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