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Magnetic helicity is approximately conserved in resistive MHD models. It quantifies the entanglement of the magnetic field within the plasma. The transport and removal of helicity is crucial in both the dynamo in the solar interior and…

Solar and Stellar Astrophysics · Physics 2020-03-25 Christopher Prior , Gareth Hawkes , Mitch Berger

We explain the (non)helical dynamo process using a field-structure model based on magnetic induction equation in an intuitive way. We show how nonhelical kinetic energy converts into magnetic energy and cascades toward smaller eddies in a…

Cosmology and Nongalactic Astrophysics · Physics 2019-02-27 Kiwan Park

We briefly review the recent developments in magnetohydrodynamics, which in particular deal with the evolution of magnetic fields in turbulent plasmas. We especially emphasize (i) the necessity of renormalizing equations of motion in…

Plasma Physics · Physics 2025-05-01 Amir Jafari

In this paper we describe the theory of a device that is able to extract energy from an external magnetic field. The device is a cylindrical magnetic insulator that once put in rotation makes electromagnetic angular momentum to be stored in…

Mathematical Physics · Physics 2012-09-21 Waldyr A. Rodrigues , Edmundo Capelas de Oliveira

We consider the magnetoelectric effect produced by a capacitor formed by two semispherical perfectly conducting plates subjected to a potential difference and surrounded by a spherical shell of a topologically insulating material. The…

Mesoscale and Nanoscale Physics · Physics 2020-07-21 Daniel G. Velázquez , L. F. Urrutia

A novel form of the current potential, a mathematical tool for the design of stellarators and stellarator coils, is developed. Specifically, these are current potentials with a finite-element-like basis, called \textit{current potential…

Plasma Physics · Physics 2024-07-10 Todd Elder , Allen H Boozer

The electron magnetohydrodynamics (MHD) contains a highly nonlinear Hall term with an interesting structure. Exploring the Hall nonlinear structure, we investigate possible phenomena of finite time blow up for the electron MHD with a…

Analysis of PDEs · Mathematics 2025-03-20 Mimi Dai

Electromagnetic potentials allow for an alternative description of the Maxwell field, the electric and magnetic components of which emerge as gradients of the vector and the scalar potential. We provide a general relativistic analysis of…

General Relativity and Quantum Cosmology · Physics 2022-04-01 Panagiotis Mavrogiannis , Christos G. Tsagas

We investigate the evolution of field line helicity for magnetic fields that connect two boundaries without null points, with emphasis on localized finite-B magnetic reconnection. Total (relative) magnetic helicity is already recognized as…

In this paper we discuss the phenomenon of resonance that we predict will occur when a superconducting coil is submitted simultaneously to a magnetic field and to an external force. When both the force and the magnetic field are constant in…

Superconductivity · Physics 2007-05-23 Osvaldo F. Schilling

It is demonstrated that targets with a broken rotational symmetry may facilitate generation of a strong axial (poloidal) magnetic field. An intense laser beam irradiating such a target creates intense electron currents carrying vorticity…

Plasma Physics · Physics 2017-04-05 Ph. Korneev , V. Tikhonchuk , E. d'Humières

Vector displacements expressed in spherical coordinates are proposed. They correspond to electromagnetic fields in vacuum that globally rotate about an axis and display many circular patterns on the surface of a sphere. The fields basically…

Classical Physics · Physics 2021-06-11 Daniele Funaro

A rigorous theory for the generation of a large-scale magnetic field by random non-helically forced motions of a conducting fluid combined with a linear shear is presented in the analytically tractable limit of low Rm and weak shear. The…

Astrophysics · Physics 2011-12-15 T. Heinemann , J. C. McWilliams , A. A. Schekochihin

Maxwell's equations and the equations governing charged particle dynamics are presented for a rotating coordinate system with the global time coordinate of an observer on the rotational axis. Special care is taken in defining the relevant…

Astrophysics · Physics 2012-08-27 Paul N. Arendt,

Potential field extrapolations are widely used as minimum-energy models for the Sun's coronal magnetic field. As the reference to which other magnetic fields are compared, they have -- by any reasonable definition -- no global (signed)…

Solar and Stellar Astrophysics · Physics 2020-08-12 A. R. Yeates

Theory and recent experiments concerning exchange-driven magnetic excitation (EDME) are reviewed. This phenomenon employs the exchange field produced by a narrowly distributed spin-polarized electron current to excite Larmor precession in a…

Condensed Matter · Physics 2007-05-23 J. C. Slonczewski

The electron states in a size-quantaized coated semiconductor wire in a uniform magnetic field applied parallel to the wire axis is considered. The wave functions are found and the equation for determination of energy eigenvalues depending…

Condensed Matter · Physics 2007-05-23 M. M. Aghasyan A. A. Kirakosyan

The prepared doctoral dissertation focuses on studying dynamics of systems composed of magnetic pendulums subjected to a non-stationary magnetic field. A magnetic pendulum is a physical pendulum with a magnet attached to its end and is…

Pattern Formation and Solitons · Physics 2024-01-22 Krystian Polczyński

Two non-local asymptotic invariants of magnetic fields for the ideal magnetohydrodynamics are introduced. The velocity of variation of the invariants for a non-ideal magnetohydrodynamics with a small magnetic dissipation is estimated. By…

Mathematical Physics · Physics 2011-10-06 Petr M. Akhmet'ev

Bitter coil is an electromagnet used for the generation of exceptionally strong magnetic fields. The upper bound of magnet flux density is restricted by several factors. One principal restriction is the high stresses due to Lorentz forces…

Instrumentation and Detectors · Physics 2016-10-26 V. Kobelev