DOE OSTI · 2999846
Periodic Korteweg–de Vries soliton potentials generate quasisymmetric magnetic field strength in a finite plasma- β equilibrium
Abstract
Quasisymmetry (QS) is a hidden symmetry of the magnetic field strength, B , that enables effective confinement of charged particles in a fully three-dimensional (3D) toroidal plasma equilibrium. Such equilibria are typically modeled by the ideal magnetohydrostatic (MHS) equations. The nonlinear, overdetermined nature of the QS MHS equations severely complicates our understanding of the interplay between 3D shaping, equilibrium properties such as pressure and rotational transform, and B . Progress has been made through expansions near the magnetic axis; however, a more comprehensive theory is desirable. Using a combination of analysis and regression on a large dataset of numerically optimized quasisymmetric stellarators, we demonstrate that there is a hidden lower dimensionality of B on a magnetic flux surface with connections to the theory of periodic solitons. We show that B on a flux surface is determined by three or at most four flux functions, each of which determines a critical value of the derivative of B along the field line. While being consistent with the near-axis models, our results are global and hold even on the last closed flux surface.
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Sengupta, W. [Princeton Univ., NJ (United States)] (ORCID:0000000234152067), Madan, R. [Princeton Univ., NJ (United States); Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)], Buller, S. [Princeton Univ., NJ (United States)] (ORCID:0000000207186712), Nikulsin, N. [Princeton Univ., NJ (United States); Max Planck Institute for Plasma Physics, Greifswald (Germany)] (ORCID:0000000318611777), Paul, E. J. [Columbia Univ., New York, NY (United States)] (ORCID:0000000293555595), Nies, R. [Princeton Univ., NJ (United States); Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)] (ORCID:0000000295081223), Kaptanoglu, A. A. [New York Univ. (NYU), NY (United States)] (ORCID:0000000263372907), Hudson, S. R. [Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)] (ORCID:0000000315302733), Bhattacharjee, A. [Princeton Univ., NJ (United States)] (ORCID:0000000164110178). 2025-10-22. Periodic Korteweg–de Vries soliton potentials generate quasisymmetric magnetic field strength in a finite plasma- β equilibrium. https://doi.org/10.1063/5.0289641
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