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We present strategies based upon extremization principles, in the case of the axisymmetric equations of magnetohydrodynamics (MHD). We study the equilibrium shape by using a minimum energy principle under the constraints of the MHD…

Fluid Dynamics · Physics 2007-05-23 Nicolas Leprovost , Pierre-Henri Chavanis , Berengere Dubrulle

Equilibrium equations for magnetically confined, axisymmetric plasmas are derived by means of the energy-Casimir variational principle in the context of Hall magnetohydrodynamics (MHD). This approach stems from the noncanonical Hamiltonian…

Plasma Physics · Physics 2023-08-01 A. Giannis , D. A. Kaltsas , G. N. Throumoulopoulos

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

We discuss tensor metric perturbations in a magnetic field around the homogeneous Juttner equilibrium of massless particles in an expanding universe. We solve the Liouville equation and derive the energy-momentum tensor up to linear terms…

General Relativity and Quantum Cosmology · Physics 2015-04-16 Z. Haba

Reduced magnetohydrodynamics is a simplified set of magnetohydrodynamics equations with applications to both fusion and astrophysical plasmas, possessing a noncanonical Hamiltonian structure and consequently a number of conserved…

Computational Physics · Physics 2017-10-05 Michael Kraus , Emanuele Tassi , Daniela Grasso

A fundamental principle of chaotic quantum dynamics is that local subsystems eventually approach a thermal equilibrium state. Large subsystems thermalize slower: their approach to equilibrium is limited by the hydrodynamic build-up of…

The hybrid Vlasov-Maxwell system of equations is suitable to describe a magnetized plasma at scales of the order of or larger than proton kinetic scales. An exact stationary solution is presented by revisiting previous results with a…

Plasma Physics · Physics 2018-06-06 F. Malara , O. Pezzi , F. Valentini

This work explores a novel approach to mitigating turbulence in fusion plasmas through spatially modulated plasma profiles. By imposing a harmonic modulation on plasma parameters, we introduce conditions that alter the propagation…

Plasma Physics · Physics 2024-12-10 Ilya Shesterikov

We propose a phenomenological theory of strong incompressible magnetohydrodynamic turbulence in the presence of a strong large-scale external magnetic field. We argue that in the inertial range of scales, magnetic-field and velocity-field…

Astrophysics · Physics 2007-05-23 Stanislav Boldyrev

Stabilizing plasma dynamics through externally applied electric and magnetic fields is a fundamental control problem. We study this question for a plasma evolving under a uniform external magnetic field. Although the governing dynamics are…

Plasma Physics · Physics 2026-03-18 Peiyi Chen , Rogerio Jorge , Qin Li , Yukun Yue

We study the intermittency and field-line structure of the MHD turbulence in plasmas with very large magnetic Prandtl numbers. In this regime, which is realized in the interstellar medium, some accretion disks, protogalaxies, galaxy-cluster…

Astrophysics · Physics 2008-11-26 A. Schekochihin , J. Maron , S. Cowley , J. McWilliams

This paper studies the turbulent cascade of magnetic energy in weakly collisional magnetized plasmas. A cascade model is presented, based on the assumptions of local nonlinear energy transfer in wavenumber space, critical balance between…

In magnetic confinement fusion devices, the ratio of the plasma pressure to the magnetic field energy, $\beta$, can become sufficiently large that electromagnetic microinstabilities become unstable, driving turbulence that distorts or…

We discuss a stochastic model for the behavior of electrons in a magnetically confined plasma having axial symmetry. The aim of the work is to provide an explanation for the density limit observed in the Frascati Tokamak Upgrade machine.…

Plasma Physics · Physics 2016-02-09 Roberto Martorelli , Giovanni Montani , Nakia Carlevaro

Understanding the physics of nonequilibrium systems remains as one of the major challenges of theoretical physics. This problem can be cracked in part by investigating the macroscopic fluctuations of the currents characterizing…

Statistical Mechanics · Physics 2014-03-18 Pablo I. Hurtado , Carlos P. Espigares , Jesus J. del Pozo , Pedro L. Garrido

Based on global conservation principles, magnetohydrodynamic (MHD) relaxation theory predicts the existence of several equilibria, such as the Taylor state or global dynamic alignment. These states are generally viewed as very long-time and…

Solar and Stellar Astrophysics · Physics 2015-06-22 S. Servidio , C. Gurgiolo , V. Carbone , M. L. Goldstein

We develop numerical methods for reaction-diffusion systems based on the equations of fluctuating hydrodynamics (FHD). While the FHD formulation is formally described by stochastic partial differential equations (SPDEs), it becomes similar…

Fluid Dynamics · Physics 2018-01-17 Changho Kim , Andy Nonaka , John B. Bell , Alejandro L. Garcia , Aleksandar Donev

We show that in a neutral magnetized plasma there exist microscopic oscillatory modes, with wavelengths of the order of magnitude of the mean interparticle distance, which become unstable when the electron density exceeds a limit…

Plasma Physics · Physics 2010-06-24 M. Marino , M. Zuin , A. Carati , E. Martines , L. Galgani

Understanding the nature of compressible fluctuations in a broad range of turbulent plasmas, from the intracluster medium to the solar wind, has been an active field of research in the past decades. Theoretical frameworks for weakly…

Solar and Stellar Astrophysics · Physics 2025-02-14 Riddhi Bandyopadhyay , James R. Beattie , Amitava Bhattacharjee

The spectrum of ideal magnetohydrodynamic (MHD) pressure-driven (ballooning) modes in strongly nonaxisymmetric toroidal systems is difficult to analyze numerically owing to the singular nature of ideal MHD caused by lack of an inherent…

Plasma Physics · Physics 2009-11-07 R. L. Dewar , C. Cuthbert , R. Ball