Multi-region relaxed magnetohydrodynamics in plasmas with slowly changing boundaries - Resonant response of a plasma slab

R. L. Dewar, S. R. Hudson, A. Bhattacharjee, Z. Yoshida

Research output: Contribution to journalArticle

2 Scopus citations

Abstract

The adiabatic limit of a recently proposed dynamical extension of Taylor relaxation, multi-region relaxed magnetohydrodynamics (MRxMHD), is summarized, with special attention to the appropriate definition of a relative magnetic helicity. The formalism is illustrated using a simple two-region, sheared-magnetic-field model similar to the Hahm-Kulsrud-Taylor (HKT) rippled-boundary slab model. In MRxMHD, a linear Grad-Shafranov equation applies, even at finite ripple amplitude. The adiabatic switching on of boundary ripple excites a shielding current sheet opposing reconnection at a resonant surface. The perturbed magnetic field as a function of ripple amplitude is calculated by invoking the conservation of magnetic helicity in the two regions separated by the current sheet. At low ripple amplitude, “half islands” appear on each side of the current sheet, locking the rotational transform at the resonant value. Beyond a critical amplitude, these islands disappear and the rotational transform develops a discontinuity across the current sheet.

Original languageEnglish (US)
Article number042507
JournalPhysics of Plasmas
Volume24
Issue number4
DOIs
StatePublished - Apr 1 2017

All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics

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