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Microscopic origins of charge currents and electromagnetic (EM) radiation generated by them in spintronic THz emitters -- such as, femtosecond laser pulse-driven single magnetic layer or its heterostructures with a nonmagnetic layer hosting…

Mesoscale and Nanoscale Physics · Physics 2024-10-01 Ali Kefayati , Branislav K. Nikolic

A formal symplectic structure on RxM is constructed for the unsteady flow of an incompressible viscous fluid on a three dimensional domain M. The evolution equation for the helicity density is expressed via the divergence of the Liouville…

Mathematical Physics · Physics 2007-05-23 Hasan Gumral

We discuss inverse problem of detection turbulence magnetic field helical properties using radio survey observations statistics. In this paper, we present principal solution which connects magnetic helicity and correlation between Faraday…

Instrumentation and Methods for Astrophysics · Physics 2010-01-19 A. Volegova , R. Stepanov

The extent to which large scale magnetic fields are susceptible to turbulent diffusion is important for interpreting the need for in situ large scale dynamos in astrophysics and for observationally inferring field strengths compared to…

Cosmology and Nongalactic Astrophysics · Physics 2015-11-18 Eric G. Blackman , Kandaswamy Subramanian

The interaction of helical convective motions and differential rotation in the solar convection zone results in turbulent drift of a large-scale magnetic field. We discuss the pumping mechanism and its impact on the solar dynamo.

Solar and Stellar Astrophysics · Physics 2015-06-12 V. V. Pipin

In this ISSI-supported series of studies on magnetic helicity in the Sun, we systematically implement different magnetic helicity calculation methods on high-quality solar magnetogram observations. We apply finite-volume, discrete flux tube…

Solar and Stellar Astrophysics · Physics 2021-11-24 J. K. Thalmann , M. K. Georgoulis , Y. Liu , E. Pariat , G. Valori , S. Anfinogentov , F. Chen , Y. Guo , K. Moraitis , S. Yang , A. Mastrano

We study the writhe, twist and magnetic helicity of different magnetic flux ropes, based on models of the solar coronal magnetic field structure. These include an analytical force-free Titov--D\'emoulin equilibrium solution, non force-free…

Solar and Stellar Astrophysics · Physics 2017-05-10 Y. Guo , E. Pariat , G. Valori , S. Anfinogentov , F. Chen , M. Georgoulis , Y. Liu , K. Moraitis , J. K. Thalmann , S. Yang

We present explicit expressions of the helicity conservation in nematic liquid crystal flows, for both the Ericksen-Leslie and Landau-de Gennes theories. This is done by using a minimal coupling argument that leads to an Euler-like equation…

Soft Condensed Matter · Physics 2010-10-18 François Gay-Balmaz , Cesare Tronci

Relative magnetic helicity is conserved by magneto-hydrodynamic evolution even in the presence of moderate resistivity. For that reason, it is often invoked as the most relevant constraint to the dynamical evolution of plasmas in complex…

Solar and Stellar Astrophysics · Physics 2020-10-28 Gherardo Valori , Pascal Démoulin , Etienne Pariat , Anthony Yeates , Kostas Moraitis , Luis Linan

The statistics of the energy and helicity fluxes in isotropic turbulence are studied using high resolution direct numerical simulation. The scaling exponents of the energy flux agree with those of the transverse velocity structure functions…

Chaotic Dynamics · Physics 2009-11-07 Qiaoning Chen , Shiyi Chen , Gregory L. Eyink , Darryl D. Holm

Magnetic helicity is a quantity that underpins many theories of magnetic relaxation in electrically conducting fluids, both laminar and turbulent. Although much theoretical effort has been expended on magnetic fields that are everywhere…

Plasma Physics · Physics 2025-04-18 Sauli Lindberg , David MacTaggart

Obtaining observational constraints on the role of turbulent effects for the solar dynamo is a difficult, yet crucial, task. Without such knowledge, the full picture of the operation mechanism of the solar dynamo cannot be formed. The…

Solar and Stellar Astrophysics · Physics 2021-10-04 A. P. Prabhu , N. K. Singh , M. J. Käpylä , A. Lagg

The evolution of magnetic fields is studied using simulations of forced helical turbulence with strong imposed shear. After some initial exponential growth, the magnetic field develops a large scale travelling wave pattern. The resulting…

Astrophysics · Physics 2009-10-31 Axel Brandenburg , Alberto Bigazzi , Kandaswamy Subramanian

Renormalized viscosity, renormalized resistivity, and various energy fluxes are calculated for helical magnetohydrodynamics using perturbative field theory. The calculation is to first-order in perturbation. Kinetic and magnetic helicities…

Chaotic Dynamics · Physics 2008-11-26 Mahendra K. Verma

We study the influence of the random part of the Galactic magnetic field on the propagation of ultra high-energy cosmic rays. Within very mild approximations about the properties of the electron density fluctuations in the Galaxy we are…

Cosmology and Nongalactic Astrophysics · Physics 2016-02-25 M. S. Pshirkov , P. G. Tinyakov , F. R. Urban

In the recent years there was published some papers in which the photons are represented as electromagnetic solitons [1,2,3]. All particles - solitons - represent some electromagnetic field restricted in a very small volume, length,…

Atomic Physics · Physics 2007-05-23 Pavel S. Kamenov

Experimental and numerical study of the steady-state cyclonic vortex from isolated heat source in a rotating fluid layer is described. The structure of laboratory cyclonic vortex is similar to the typical structure of tropical cyclones from…

Fluid Dynamics · Physics 2017-05-03 A. Sukhanovskii , A. Evgrafova , E. Popova

The current driven magnetisation dynamics of a helical spin-density wave is investigated. Expressions for calculating the spin-transfer torque of real systems from first principles density functional theory are presented. These expressions…

Materials Science · Physics 2009-11-13 O. Wessely , B. Skubic , L. Nordstrom

A decomposition of the energy and helicity fluxes in a turbulent hydrodynamic flow is proposed. The decomposition is based on the projection of the flow to a helical basis that allows to investigate separately the role of interactions among…

Fluid Dynamics · Physics 2017-03-08 Alexandros Alexakis

In my thesis, I first develop the theoretical basis and tools for the use of helicity and duality in the study, understanding and engineering of interactions between electromagnetic radiation and material systems. Then, within the general…

Optics · Physics 2015-12-17 Ivan Fernandez-Corbaton