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A new formulation of time-dependent Relaxed Magnetohydrodynamics (RxMHD) is derived variationally from Hamilton's Action Principle using microscopic conservation of mass, and macroscopic conservation of total magnetic helicity, cross…

Plasma Physics · Physics 2020-06-04 R. L. Dewar , J. W. Burby , Z. Qu , N. Sato , M. J. Hole

The gap between a recently developed dynamical version of relaxed magnetohydrodynamics (RxMHD) and ideal MHD (IMHD) is bridged by approximating the zero-resistivity "Ideal" Ohm's Law (IOL) constraint using an augmented Lagrangian method…

Plasma Physics · Physics 2022-02-23 R. L. Dewar , Z. S. Qu

The adiabatic limit of a recently proposed dynamical extension of Taylor relaxation, \emph{multi-region relaxed magnetohydrodynamics} (MRxMHD) is summarized, with special attention to the appropriate definition of relative magnetic…

Plasma Physics · Physics 2017-04-05 Robert L. Dewar , Stuart R. Hudson , Amitava Bhattacharjee , Zensho Yoshida

We present an extension of the multi-region relaxed magnetohydrodynamics (MRxMHD) equilibrium model that includes pressure anisotropy and general plasma flows. This anisotropic extension to our previous isotropic model is motivated by Sun…

Plasma Physics · Physics 2015-06-19 Graham R. Dennis , Stuart R. Hudson , Robert L. Dewar , Matthew J. Hole

A multi-symplectic formulation of ideal magnetohydrodynamics (MHD) is developed based on a Clebsch variable variational principle in which the Lagrangian consists of the kinetic minus the potential energy of the MHD fluid modified by…

Mathematical Physics · Physics 2019-02-20 G. M. Webb , J. F. McKenzie , G. P. Zank

Stability conditions of magnetized plasma flows are obtained by exploiting the Hamiltonian structure of the magnetohydrodynamics (MHD) equations and, in particular, by using three kinds of energy principles. First, the Lagrangian variable…

Plasma Physics · Physics 2015-06-16 T. Andreussi , P. J. Morrison , F. Pegoraro

The recent formulations of multi-region relaxed magnetohydrodynamics (MRxMHD) have generalized the famous Woltjer-Taylor states by incorporating a collection of "ideal barriers" that prevent global relaxation, and flow. In this paper, we…

Plasma Physics · Physics 2016-08-04 Manasvi Lingam , Hamdi M. Abdelhamid , Stuart R. Hudson

We describe a magnetohydrodynamic (MHD) constrained energy functional for equilibrium calculations that combines the topological constraints of ideal MHD with elements of Taylor relaxation. Extremizing states allow for partially chaotic…

Plasma Physics · Physics 2012-04-03 S. R. Hudson , R. L. Dewar , M. J. Hole , M. McGann

A unified energy principle approach is presented for analysing the magnetohydrodynamic (MHD) stability of plasmas consisting of multiple ideal and relaxed regions. By choosing an appropriate gauge, we show that the plasma displacement…

Plasma Physics · Physics 2015-05-13 R. L. Mills , M. J. Hole , R. L. Dewar

We show the stepped-pressure equilibria that are obtained from a generalization of Taylor relaxation known as multi-region, relaxed MHD (MRXMHD) are also generalizations of ideal MHD. We show this by proving that as the number of plasma…

Plasma Physics · Physics 2013-06-25 G. R. Dennis , S. R. Hudson , R. L. Dewar , M. J. Hole

We present an extension of the multi-region relaxed magnetohydrodynamics (MRxMHD) equilibrium model that includes plasma flow. This new model is a generalization of Woltjer's model of relaxed magnetohydrodynamics equilibria with flow. We…

Plasma Physics · Physics 2014-04-04 G. R. Dennis , S. R. Hudson , R. L. Dewar , M. J. Hole

A general formulation of the problem of calculating the spectrum of stable and unstable eigenmodes of linearized perturbations about a magnetically confined toroidal plasma is presented. The analysis is based on a new hydromagnetic…

Plasma Physics · Physics 2017-03-07 Robert L Dewar , Li Huey Tuen , Matthew J Hole

In this tutorial, a derivation of magnetohydrodynamics (MHD) valid beyond the usual ideal gas approximation is presented. Non-equilibrium thermodynamics is used to obtain conservation equations and linear constitutive relations. When…

Plasma Physics · Physics 2025-04-21 Jarett LeVan , Scott Baalrud

Extended magnetohydrodynamics (XMHD) is a fluid plasma model generalizing ideal MHD by taking into account the impact of Hall drift effects and the influence of electron inertial effects. XMHD has a Hamiltonian structure which has received…

Analysis of PDEs · Mathematics 2024-06-26 Christophe Cheverry , Nicolas Besse

We report the first measurements of equations of state of a fully relaxed magnetohydrodynamic (MHD) laboratory plasma. Parcels of magnetized plasma, called Taylor states, are formed in a coaxial magnetized plasma gun, and are allowed to…

Plasma Physics · Physics 2018-01-17 M. Kaur , L. J. Barbano , E. M. Suen-Lewis , J. E. Shrock , A. D. Light , D. A. Schaffner , M. R. Brown

This paper considers magnetohydrodynamics (MHD) and some of its applications from the perspective of differential geometry, considering the dynamics of an ideal fluid flow and magnetic field on a general three-dimensional manifold, equipped…

Fluid Dynamics · Physics 2023-07-26 Andrew D. Gilbert , Jacques Vanneste

We revisit the issue of conservation of magnetic helicity and the Woltjer-Taylor relaxation theory in magnetohydrodynamics in the context of weak solutions. We introduce a relaxed system for the ideal MHD system, which decouples the effects…

Analysis of PDEs · Mathematics 2021-09-21 Daniel Faraco , Sauli Lindberg , László Székelyhidi

We describe the construction of stepped-pressure equilibria as extrema of a multi-region, relaxed magnetohydrodynamic (MHD) energy functional that combines elements of ideal MHD and Taylor relaxation, and which we call MRXMHD. The model is…

Plasma Physics · Physics 2015-06-12 S. R. Hudson , R. L. Dewar , G. Dennis , M. J. Hole , M. McGann , G. von Nessi , S. Lazerson

In this paper we show how a Lagrangian variational principle can be used to derive the SPMHD (smoothed particle magnetohydrodynamics) equations for ideal MHD. We also consider the effect of a variable smoothing length in the SPH kernels…

Astrophysics · Physics 2009-11-10 D. J. Price , J. J. Monaghan

We show that the variational energy principle of multi-region relaxed magnetohydrodynamic (MRxMHD) model can be used to predict finite-pressure linear tearing instabilities. In this model, the plasma volume is sliced into sub-volumes…

Plasma Physics · Physics 2023-06-07 A. Kumar , J. Loizu , M. J. Hole , Z. Qu , S. R. Hudson , R. L Dewar
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