Steepest‐descent moment method for three‐dimensional magnetohydrodynamic equilibria
作者:
S. P. Hirshman,
J. C. Whitson,
期刊:
Physics of Fluids(00319171)
(AIP Available online 1983)
卷期:
Volume 26,
issue 12
页码: 3553-3568
ISSN:0031-9171
年代: 1983
DOI:10.1063/1.864116
出版商: AIP
数据来源: AIP
摘要:
An energy principle is used to obtain the solution of the magnetohydrodynamic (MHD) equilibrium equationJ×B−∇p=0 for nested magnetic flux surfaces that are expressed in the inverse coordinate representationx=x(&rgr;, &thgr;, &zgr;). Here, &thgr; are &zgr; are poloidal and toroidal flux coordinate angles, respectively, andp=p(&rgr;) labels a magnetic surface. Ordinary differential equations in &rgr; are obtained for the Fourier amplitudes (moments) in the doubly periodic spectral decomposition ofx. A steepest‐descent iteration is developed for efficiently solving these nonlinear, coupled moment equations. The existence of a positive‐definite energy functional guarantees the monotonic convergence of this iteration toward an equilibrium solution (in the absence of magnetic island formation). A renormalization parameter &lgr; is introduced to ensure the rapid convergence of the Fourier series forx, while simultaneously satisfying the MHD requirement that magnetic field lines are straight in flux coordinates. A descent iteration is also developed for determining the self‐consistent value for &lgr;.
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