Formation of current singularity in a topologically constrained plasma
Authors: Yao Zhou, Yi-Min Huang, Hong Qin,
and A. Bhattacharjee
Abstract: Recently a variational integrator for
ideal magnetohydrodynamics in Lagrangian labeling has been
developed using discrete exterior calculus. Its built-in frozen-in
equation makes it optimal for studying current sheet formation. We
use this scheme to study the Hahm-Kulsrud-Taylor problem, which
considers the response of a 2D plasma magnetized by a sheared
field under mirrored sinusoidal boundary forcing. We obtain
equilibrium solutions that preserve the topology of the initial
field exactly, with a fluid mapping that is non-di fferentiable.
Unlike previous studies that examine the current density output,
we identify a singular current sheet from the fluid mapping. The
results are benchmarked with an unconventional Grad-Shafranov
solver.
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Submitted to: Physical Review Letters
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