Vacuum magnetic fields with exact quasisymmetry near a flux surface. Part 1. Solutions near an axisymmetric surface

Sengupta, Wrick; Paul, Elizabeth J.; Weitzner, Harold; Bhattacharjee, Amitava

doi:10.1017/s0022377821000039

Vacuum magnetic fields with exact quasisymmetry near a flux surface. Part 1. Solutions near an axisymmetric surface

Journal Article · Mon Mar 08 23:00:00 EST 2021 · Journal of Plasma Physics

DOI:https://doi.org/10.1017/s0022377821000039· OSTI ID:1849937

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OSTI

While several results have pointed to the existence of exactly quasisymmetric fields on a surface (Garren & Boozer,Phys. FluidsB, vol. 3, 1991, pp. 2805–2821; 2822–2834; Plunk & Helander,J. Plasma Phys., vol. 84, 2018, 905840205), we have obtained the first such solutions using a vacuum surface expansion formalism. We obtain a single nonlinear parabolic partial differential equation for a function$$\eta$$such the field strength satisfies$$B = B(\eta )$$. Closed-form solutions are obtained in cylindrical, slab and isodynamic geometries. Numerical solutions of the full nonlinear equations in general axisymmetric toroidal geometry are obtained, resulting in a class of quasihelical local vacuum equilibria near an axisymmetric surface. The analytic models provide additional insight into general features of the nonlinear solutions, such as localization of the surface perturbations on the inboard side. The local solutions thus obtained can be continued globally only for special initial surfaces.

Research Organization:: New York Univ. (NYU), NY (United States)

Sponsoring Organization:: USDOE Office of Science (SC)

DOE Contract Number:: FG02-86ER53223

OSTI ID:: 1849937

Journal Information:: Journal of Plasma Physics, Journal Name: Journal of Plasma Physics Journal Issue: 2 Vol. 87; ISSN 0022-3778

Publisher:: Cambridge University Press

Country of Publication:: United States

Language:: English

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