scholarly journals Optical Birefringence Growth Driven by Magnetic Field in Liquids: The Case of Dibutyl Phosphate/Propylamine System

2019 ◽  
Vol 10 (1) ◽  
pp. 164 ◽  
Author(s):  
Mikolaj Pochylski ◽  
Domenico Lombardo ◽  
Pietro Calandra
Keyword(s):  
Magnetic Field ◽  
Self Assembly ◽  
Magnetic Field Intensity ◽  
Magnetic Energy ◽  
Molar Ratio ◽  
Molecular Liquids ◽  
Microscopic Scale ◽  
Intensity Response ◽  
Soft Particles ◽  
The Magnetic Field

Magnetically-induced birefringence is usually low in molecular liquids owing to the low magnetic energy of molecules with respect to the thermal one. Despite this, it has been found that a mixture of dibutyl phosphate and propylamine at propylamine molar ratio (X) around 0.33 surprisingly gives an intense effect (∆n/λ ≈ −0.1 at 1 Tesla). In this paper the time- and intensity- response to the magnetic field of such mixture have been studied. It was found that the reaction to the magnetic field is unusually slow (from several minutes to hours) depending of the magnetic field intensity. On the basis of the data, the model of orientable dipoles dispersed in a matrix enables to interpret the magnetic field-induced self-assembly in terms of soft molecules-based nanostructures. The analogy with systems made of magnetically polarizable (solid or soft) particles dispersed in liquid carrier allows understanding, at the microscopic scale, the molecular origin and the supra-molecular dynamics involved in the observed behavior. The data present a novel phenomenon in liquid phase where the progressive building up/change of ordered and strongly interacting amphiphiles is driven by the magnetic field.

scholarly journals The thermodynamics of magnetization.

1936 ◽  
Vol 155 (884) ◽  
pp. 70-101 ◽  
Author(s):  
Edward Armand Guggenheim ◽  
Charles Galton Darwin
Keyword(s):  
Magnetic Field ◽  
Field Intensity ◽  
Magnetic Induction ◽  
Magnetic Field Intensity ◽  
Magnetic Energy ◽  
Comprehensive Treatment ◽  
Accurate Analysis ◽  
General Validity ◽  
Magnetic Systems ◽  
The Magnetic Field

An accurate analysis of the thermodynamics of magnetic systems has to our knowledge never been made. The accounts given in the usual sources of reference are slight. Quite recently Stoner has tried to remedy this deficiency by a paper full of interest, but there are several points in his treatment which seem to us not altogether free from objection. We are therefore attempting in the present paper to give an accurate and fairly comprehensive treatment of the subject, in which the method of approach is somewhat different. This treatment seems to clarify the situation considerably. In particular we give a much more thorough analysis of pressure-volume effects than has previously been attempted. At the end of our paper we consider the relation between some of Stoner's formulae and our own. The thermodynamics of magnetic systems may be regarded as an extension of the electrodynamics of such systems to take account of thermal changes and volume changes of the magnetic matter. The chief difficulty encountered was that of finding a logically consistent treatment of magnetic energy from a purely electrodynamic aspect. In most of the recognized text-books either the treatment is not self-consistent or else it is assumed that the ratio of the magnetic induction to the magnetic field intensity is a constant. In a thermodynamic treatment this assumption may not be made even for diamagnetic and paramagnetic substances, because even supposing it to be valid at constant temperature it will not be valid when the temperature varies. Nor ca it generally be accurate both for variations at constant volume and for variations at constant pressure. It is therefore essential to start with a formula for magnetic energy which is independent of any assumed relation between the magnetic induction and the magnetic field intensity other than that each is a single valued continuous function of the other. This subject has been discussed in another paper where a formula of general validity for magnetic energy was obtained. We shall make this the basis of the present treatment.

CHOICE OF CONDITIONS FOR MHD SIMULATIONS ABOVE THE ACTIVE REGION, ALLOWING THE STUDY OF THE SOLAR FLARE MECHANISM

2021 ◽  
Vol 44 ◽  
pp. 92-95
Author(s):  
A.I. Podgorny ◽  
◽  
I.M. Podgorny ◽  
A.V. Borisenko ◽  
N.S. Meshalkina ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Active Region ◽  
Solar Flare ◽  
Magnetic Energy ◽  
Solar Radius ◽  
Computational Domain ◽  
Mhd Simulations ◽  
Flare Energy ◽  
Numerical Instabilities ◽  
The Magnetic Field

Primordial release of solar flare energy high in corona (at altitudes 1/40 - 1/20 of the solar radius) is explained by release of the magnetic energy of the current sheet. The observed manifestations of the flare are explained by the electrodynamical model of a solar flare proposed by I. M. Podgorny. To study the flare mechanism is necessary to perform MHD simulations above a real active region (AR). MHD simulation in the solar corona in the real scale of time can only be carried out thanks to parallel calculations using CUDA technology. Methods have been developed for stabilizing numerical instabilities that arise near the boundary of the computational domain. Methods are applicable for low viscosities in the main part of the domain, for which the flare energy is effectively accumulated near the singularities of the magnetic field. Singular lines of the magnetic field, near which the field can have a rather complex configuration, coincide or are located near the observed positions of the flare.

scholarly journals The development of magnetic field line wander by plasma turbulence

2017 ◽  
Vol 83 (4) ◽  
Author(s):  
Gregory G. Howes ◽  
Sofiane Bourouaine
Keyword(s):  
Magnetic Field ◽  
Field Line ◽  
Magnetic Field Line ◽  
Large Scale ◽  
Magnetic Energy ◽  
Plasma Turbulence ◽  
Alfven Wave ◽  
Astrophysical Plasmas ◽  
Field Lines ◽  
The Magnetic Field

Plasma turbulence occurs ubiquitously in space and astrophysical plasmas, mediating the nonlinear transfer of energy from large-scale electromagnetic fields and plasma flows to small scales at which the energy may be ultimately converted to plasma heat. But plasma turbulence also generically leads to a tangling of the magnetic field that threads through the plasma. The resulting wander of the magnetic field lines may significantly impact a number of important physical processes, including the propagation of cosmic rays and energetic particles, confinement in magnetic fusion devices and the fundamental processes of turbulence, magnetic reconnection and particle acceleration. The various potential impacts of magnetic field line wander are reviewed in detail, and a number of important theoretical considerations are identified that may influence the development and saturation of magnetic field line wander in astrophysical plasma turbulence. The results of nonlinear gyrokinetic simulations of kinetic Alfvén wave turbulence of sub-ion length scales are evaluated to understand the development and saturation of the turbulent magnetic energy spectrum and of the magnetic field line wander. It is found that turbulent space and astrophysical plasmas are generally expected to contain a stochastic magnetic field due to the tangling of the field by strong plasma turbulence. Future work will explore how the saturated magnetic field line wander varies as a function of the amplitude of the plasma turbulence and the ratio of the thermal to magnetic pressure, known as the plasma beta.

scholarly journals Magnetotaxis as a Means for Nanofabrication

2014 ◽  
Vol 23 (01n02) ◽  
pp. 1450008
Author(s):  
Isaac Macwan ◽  
Zihe Zhao ◽  
Omar Sobh ◽  
Jinnque Rho ◽  
Ausif Mahmood ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Geomagnetic Field ◽  
Semiconductor Manufacturing ◽  
Magnetic Field Intensity ◽  
Magnetotactic Bacteria ◽  
Semiconductor Substrate ◽  
Field Lines ◽  
A Chain ◽  
Magnetospirillum Magneticum ◽  
The Magnetic Field

Magnetotactic bacteria (MTB), discovered in early 1970s contain single-domain crystals of magnetite ( Fe 3 O 4) called magnetosomes that tend to form a chain like structure from the proximal to the distal pole along the long axis of the cell. The ability of these bacteria to sense the magnetic field for displacement, also called magnetotaxis, arises from the magnetic dipole moment of this chain of magnetosomes. In aquatic habitats, these organisms sense the geomagnetic field and traverse the oxic-anoxic interface for optimal oxygen concentration along the field lines. Here we report an elegant use of MTB where magnetotaxis of Magnetospirillum magneticum (classified as AMB-1) could be utilized for controlled navigation over a semiconductor substrate for selective deposition. We examined 50mm long coils made out of 18AWG and 20AWG copper conductors having diameters of 5mm, 10mm and 20mm for magnetic field intensity and heat generation. Based on the COMSOL simulations and experimental data, it is recognized that a compound semiconductor manufacturing technology involving bacterial carriers and carbon-based materials such as graphene and carbon nanotubes would be a desirable choice in the future.

Kinematic dynamo problem in a linear velocity field

1984 ◽  
Vol 144 ◽  
pp. 1-11 ◽  
Author(s):  
Ya. B. Zel'Dovich ◽  
A. A. Ruzmaikin ◽  
S. A. Molchanov ◽  
D. D. Sokoloff
Keyword(s):  
Magnetic Field ◽  
Spatial Distribution ◽  
Velocity Field ◽  
Random Matrix ◽  
Magnetic Energy ◽  
Linear Velocity ◽  
Finite Conductivity ◽  
Kinematic Dynamo ◽  
Linear Velocity Field ◽  
The Magnetic Field

A magnetic field is shown to be asymptotically (t → ∞) decaying in a flow of finite conductivity with v = Cr, where C = Cζ(t) is a random matrix. The decay is exponential, and its rate does not depend on the conductivity. However, the magnetic energy increases exponentially owing to growth of the domain occupied by the field. The spatial distribution of the magnetic field is a set of thin ropes and (or) layers.

Tunable amplified spontaneous emission based on liquid magnetically responsive photonic crystals

2019 ◽  
Vol 7 (13) ◽  
pp. 3740-3743 ◽  
Author(s):  
Ying Li ◽  
Yue Long ◽  
Guoqiang Yang ◽  
Chen-Ho Tung ◽  
Kai Song
Keyword(s):  
Magnetic Field ◽  
Photonic Crystals ◽  
Spontaneous Emission ◽  
Field Intensity ◽  
Magnetic Field Intensity ◽  
Amplified Spontaneous Emission ◽  
The Magnetic Field

The wavelength of amplified spontaneous emission based on liquid magnetically responsive photonic crystals can be tuned by simply changing the magnetic field intensity.

Fast magnetic field penetration into low resistivity plasma

2017 ◽  
Vol 83 (1) ◽  
Author(s):  
Amnon Fruchtman
Keyword(s):  
Magnetic Field ◽  
Energy Dissipation ◽  
Electric Field ◽  
Density Gradient ◽  
Magnetic Energy ◽  
Measured Velocity ◽  
Magnetic Field Penetration ◽  
The Magnetic Field ◽  
Uniform Plasma ◽  
Field Penetration

Penetration of a magnetic field into plasma that is faster than resistive diffusion can be induced by the Hall electric field in a non-uniform plasma. This mechanism explained successfully the measured velocity of the magnetic field penetration into pulsed plasmas. Major related issues have not yet been resolved. Such is the theoretically predicted, but so far not verified experimentally, high magnetic energy dissipation, as well as the correlation between the directions of the density gradient and of the field penetration.

Existence and Energy Balance of the Solar Dynamo

1993 ◽  
Vol 157 ◽  
pp. 19-23
Author(s):  
J.H.G.M. van Geffen
Keyword(s):  
Magnetic Field ◽  
Energy Balance ◽  
Energy Method ◽  
Magnetic Energy ◽  
Mean Field ◽  
Solar Dynamo ◽  
Ensemble Averaging ◽  
Dynamo Theory ◽  
The Magnetic Field ◽  
Mean Field Dynamo

The idea behind the use of ensemble averaging and the finite magnetic energy method of van Geffen and Hoyng (1992) is briefly discussed. Applying this method to the solar dynamo shows that the turbulence — an essential ingredient of traditional mean field dynamo theory — poses grave problems: the turbulence makes the magnetic field so unstable that it becomes impossible to recognize any period.

scholarly journals Multi-point observations of intermittency in the cusp regions

2007 ◽  
Vol 14 (4) ◽  
pp. 525-534 ◽  
Author(s):  
M. M. Echim ◽  
H. Lamy ◽  
T. Chang
Keyword(s):  
Magnetic Field ◽  
Magnetic Energy ◽  
Haar Wavelet ◽  
Distribution Functions ◽  
Statistical Properties ◽  
Coarse Grained ◽  
Haar Wavelet Transform ◽  
Intermittent Behavior ◽  
Field Fluctuations ◽  
The Magnetic Field

Abstract. In this paper we investigate the statistical properties of magnetic field fluctuations measured by the four Cluster spacecraft in the cusp and close to the interface with the magnetospheric lobes, magnetopause and magnetosheath. At lower altitudes along the outbound orbit of 26 February 2001, the magnetic field fluctuations recorded by all four spacecraft are random and their Probability Distribution Functions (PDFs) are Gaussian at all scales. The flatness parameter, F – related to the kurtosis of the time series, is equal to 3. At higher altitudes, in the cusp and its vicinity, closer to the interface with the magnetopause and magnetosheath, the PDFs from all Cluster satellites are non-Gaussian and show a clear intermittent behavior at scales smaller than τG≈ 61 s (or 170 km). The flatness parameter increases to values greater than 3 for scales smaller than τG. A Haar wavelet transform enables the identification of the "events" that produce sudden variations of the magnetic field and of the scales that have most of the power. The LIM parameter (i.e. normalized wavelet power) indicates that events for scales below 65 s are non-uniformly distributed throughout the cusp passage. PDFs, flatness and wavelet analysis show that at coarse-grained scales larger than τG the intermittency is absent in the cusp. Fluctuations of the magnetic energy observed during the same orbit in the magnetosheath show PDFs that tend toward a Gaussian at scales smaller than τG found in the cusp. The flatness analysis confirms the decreasing of τG from cusp to magnetosheath. Our analysis reveals the turbulent cusp as a transition region from a non-intermittent turbulent state inside the magnetosphere to an intermittent turbulent state in the magnetosheath that has statistical properties resembling the solar wind turbulence. The observed turbulent fluctuations in the cusp suggests a phenomenon of nonlinear interactions of plasma coherent structures as in contemporary models of space plasma turbulence.

Toward a Contactless Hydrokinetic Energy Harvester: A Computational Magnetic Field Estimation

2018 ◽  
Author(s):  
Georgios Tsakyridis ◽  
Nikolaos I. Xiros ◽  
Michael M. Bernitsas
Keyword(s):  
Magnetic Field ◽  
Energy Harvesting ◽  
Attitude Control ◽  
Magnetic Levitation ◽  
Magnetic Energy ◽  
Hydrodynamic Drag ◽  
Core Element ◽  
Hydrokinetic Energy ◽  
Ferromagnetic Core ◽  
The Magnetic Field

Magnetic levitation (maglev) concepts are applied to a variety of industries such as the automotive, aerospace, or energy in order to accomplish different tasks: suspension and propulsion in maglev trains, rocket propulsion and spacecraft attitude control, centrifuge of nuclear reactors. In this paper, maglev is implemented in environmentally friendly hydrokinetic energy harvesting to achieve contactless bearing, thus, minimizing friction and improving efficiency. Generally, maglev systems exhibit higher efficiency and reduced maintenance while providing longer lifetime and higher durability when appropriate engineering design and control are applied. A Flow Induced Oscillation (FIO) energy-harvesting converter is considered in this work. To minimize friction in the support of the cylinder in FIO (vortex induced vibrations and galloping) due to high hydrodynamic drag, a maglev system is proposed. In the proposed configuration, a ferromagnetic core (element 1), of known dimensions, is considered under the effects of an externally imposed magnetic field. A second ferromagnetic element, of smaller dimensions, is then placed adjacent to the previous considered core. This particular configuration results in a non-homogenous magnetic field for element 1, caused by dimensional disparity. Specifically, the magnetic flux does not follow a linear path from the ferromagnetic core to element 2. A general electromagnetic analysis is conducted to derive an analytical form for the magnetic field of element 1. Subsequent numerical simulation validates the obtained formula. This distinct expression for the magnetic field is valuable towards calculating the magnetic energy of this specific configuration, which is essential to the design of the FIO energy harvesting converter considered in this work.

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