Recent advances in the design of quasiaxisymmetric stellarator plasma configurations

Reiman, A.; Ku, L. P.; Monticello, D.; Hirshman, S. P.; Hudson, S. R.; Kessel, C.; Lazarus, E. A.; Mikkelsen, D. R.; Zarnstorff, M. C.; Berry, L. A.; Boozer, Allen H.; Brooks, A.; Cooper, W. A.; Drevlak, M.; Fredrickson, E. D.; Fu, G. Y.; Goldston, Robert James; Hatcher, R.; Isaev, M. Yu.; Cheng, J.; Knowlton, S.; Lewandowski, J. L. V.; Zhang, Lin; Lyon, J. F.; Merkel, P.; Михайлов, М. И.; Miner, W. H.; Mynick, H.; Neilson, G.H.; Nelson, B.; Nührenberg, C.; Pomphrey, N.; Redi, M. H.; Reiersen, W.; Rutherford, P. H.; Sánchez, Raúl; Schmidt, J.; Spong, D. A.; Strickler, D. J.; Субботин, А. А.; Valanju, P.; White, R. B.

doi:10.1063/1.1351826

Cited by 47 publications

(26 citation statements)

References 26 publications

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“…For example, 49 flux magnetic surfaces were consistently retained in the equilibrium solutions and 91 selected perturbation modes in the stability calculations. The plasma pressure and bootstrap current profiles were taken from NCSX [24] but adjusted to obtained a fixed β = 4% and to reflect changes in the aspect ratio and the level of rotational transform, which means a correction for R · B t and the trapped particle fraction.…”

Section: Approach and Methodsmentioning

confidence: 99%

Nonaxisymmetric shaping of tokamaks preserving quasiaxisymmetry

Boozer

2009

Physics of Plasmas

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If quasi-axisymmetry is preserved, non-axisymmetric shaping can be used to design tokamaks that do not require current drive, are resilient to disruptions, and have robust plasma stability without feedback. Suggestions for addressing the critical issues of tokamaks can only be validated when presented with sufficient specificity that validating experiments can be designed. The purpose of this paper is provide that specificity for non-axisymmetric shaping. To our knowledge, no other suggestions for the solution of a number of tokamak issues, such as disruptions, have reached this level of specificity. Sequences of three-field-period quasi-axisymmetric plasmas are studied. These sequences address the questions: (1) What can be achieved at various levels of non-axisymmetric shaping? (2) What simplifications to the coils can be achieved by going to a larger aspect ratio? (3) What range of shaping can be achieved in a single experimental facility? The sequences of plasmas found in this study provide a set of interesting and potentially important configurations.

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Section: Approach and Methodsmentioning

confidence: 99%

Nonaxisymmetric shaping of tokamaks preserving quasiaxisymmetry

Boozer

2009

Physics of Plasmas

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“…The method is applied to a stellarator design considered for the National Compact Stellarator eXperiment (NCSX) [6]. Features of the design make special demands on the coil design to avoid magnetic islands.…”

Section: Th/6-2mentioning

confidence: 99%

“…Small high-order islands, (n, m) = (3, 7), (6,12), (6,11), (6,10) and (9,14), that have not boundaries is good, but not perfect. The difference may result from the existence of small residual islands in the PIES equilibrium.…”

Section: Th/6-2 10mentioning

confidence: 99%

Constructing integrable high-pressure full-current free-boundary stellarator magnetohydrodynamic equilibrium solutions

Hudson¹,

Monticello²,

Reiman³

et al. 2003

Nucl. Fusion

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Abstract. For the (non-axisymmetric) stellarator class of plasma confinement devices to be feasible candidates for fusion power stations it is essential that, to a good approximation, the magnetic field lines lie on nested flux surfaces; however, the inherent lack of a continuous symmetry implies that magnetic islands responsible for breaking the smooth topology of the flux surfaces are guaranteed to exist. Thus, the suppression of magnetic islands is a critical issue for stellarator design, particularly for small aspect ratio devices. Pfirsch-Schlüter currents, diamagnetic currents and resonant coil fields contribute to the formation of magnetic islands, and the challenge is to design the plasma and coils such that these effects cancel.Magnetic islands in free-boundary high-pressure full-current stellarator magnetohydrodynamic equilibria are suppressed using a procedure based on the Princeton Iterative Equilibrium Solver [Comp. Phys. Comm., 43:157, 1986] which iterates the equilibrium equations to obtain the TH/6-2 2 plasma equilibrium. At each iteration, changes to a Fourier representation of the coil geometry are made to cancel resonant fields produced by the plasma. The changes are constrained to preserve certain measures of engineering acceptability and to preserve the stability of ideal kink modes. As the iterations continue, the coil geometry and the plasma simultaneously converge to an equilibrium in which the island content is negligible, the plasma is stable to ideal kink modes, and the coils satisfy engineering constraints. The method is applied to a candidate plasma and coil design for the National Compact Stellarator eXperiment [Phys. Plas. 8(5):2083Plas. 8(5): , 2001].

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“…[1] This was also the line of reasoning, in part, that motivated the physics design study for the US National Compact Stellarator Experiment (NCSX) (Ref. [2] and references therein), presently under construction. In this paper we show that vertical instability of the tokamak plasma, which imposes an important constraint on tokamak design, can be controlled by nonaxisymmetric magnetic fields localized near the plasma edge at the bottom and top of the torus.…”

mentioning

confidence: 99%

Recent advances in the design of quasiaxisymmetric stellarator plasma configurations

Cited by 47 publications

References 26 publications

Nonaxisymmetric shaping of tokamaks preserving quasiaxisymmetry

Nonaxisymmetric shaping of tokamaks preserving quasiaxisymmetry

Constructing integrable high-pressure full-current free-boundary stellarator magnetohydrodynamic equilibrium solutions

Stabilization of the Vertical Mode in Tokamaks by Localized Nonaxisymmetric Fields

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