scholarly journals The Oriented and Flux-Weighted Current Density Stagnation Graph of LiH

2022 ◽  
Author(s):  
Raphael J F Berger ◽  
Maria Dimitrova
Keyword(s):  
Magnetic Field ◽  
Vector Field ◽  
External Magnetic Field ◽  
Current Density ◽  
Vector Fields ◽  
Connected Subset ◽  
Theoretical Limit ◽  
Density Vector ◽  
Topological Characteristics ◽  
Zero Points

A scheme is introduced to quantitatively analyze the magnetically induced molecular current density vector field $\mathbf{J}$. After determining the set of zero points of $\mathbf{J}$, which is called its {\em stagnation graph} (SG), the line integrals $\Phi_{\ell_i}=-\frac{1}{\mu_0} \int_{\ell_i} \mathbf{B}_\mathrm{ind}\cdot\mathrm{d}\mathbf{l}$ along all edges $\ell_i$ of the connected subset of the SG are determined. The edges $\ell_i$ are oriented such that all $\Phi_{\ell_i}$ are non-negative and they are weighted with $\Phi_{\ell_i}$. An oriented flux-weighted (current density) stagnation graph (OFW-SG) is obtained. Since $\mathbf{J}$ is in the exact theoretical limit divergence free and due to the topological characteristics of such vector fields the flux of all separate vortices and neighbouring vortex combinations can be determined by adding the weights of cyclic subsets of edges of the OFW-SG. The procedure is exemplified by the case of LiH for a perpendicular and weak homogeneous external magnetic field $\mathbf{B}$}

scholarly journals ARBTools: A Tricubic Spline Interpolator for Three-Dimensional Scalar or Vector Fields

2019 ◽  
Author(s):  
Paul Walker ◽  
Ulrich Krohn ◽  
Carty David
Keyword(s):  
Magnetic Field ◽  
Vector Field ◽  
Vector Fields ◽  
Three Dimensional ◽  
Spline Method ◽  
Particle Trajectories ◽  
The Core ◽  
Numerical Integrators ◽  
Data Points ◽  
System Requirements

ARBTools is a Python library containing a Lekien-Marsden type tricubic spline method for interpolating three-dimensional scalar or vector fields presented as a set of discrete data points on a regular cuboid grid. ARBTools was developed for simulations of magnetic molecular traps, in which the magnitude, gradient and vector components of a magnetic field are required. Numerical integrators for solving particle trajectories are included, but the core interpolator can be used for any scalar or vector field. The only additional system requirements are NumPy.

scholarly journals Fault Identification on a Fuel Cell by 3-D Current Density Reconstruction From External Magnetic Field Measurements

2019 ◽  
Vol 55 (6) ◽  
pp. 1-5 ◽  
Author(s):  
Lyes Ifrek ◽  
Olivier Chadebec ◽  
Sebastien Rosini ◽  
Gilles Cauffet ◽  
Yann Bultel ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Fuel Cell ◽  
External Magnetic Field ◽  
Current Density ◽  
Field Measurements ◽  
Fault Identification ◽  
Magnetic Field Measurements

scholarly journals Температурные зависимости критических параметров неоднородных сверхпроводящих пленок

2021 ◽  
Vol 63 (8) ◽  
pp. 1035
Author(s):  
П.И. Безотосный ◽  
К.А. Дмитриева
Keyword(s):  
Magnetic Field ◽  
Critical Temperature ◽  
External Magnetic Field ◽  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Superconducting Films ◽  
Critical Magnetic Field ◽  
Temperature Dependences ◽  
Comparison Of The Results

The results of calculating the temperature dependences of the critical current density and critical magnetic field of thin inhomogeneous superconducting films are presented. Comparison of the results obtained for inhomogeneous films with the results of calculations for homogeneous ones showed that in both cases, the decrease in the critical magnetic field occurs according to the root law, and the critical current density changes according to a power law with a degree of 3/2 when approaching the critical temperature. Quantitatively, the critical current density for inhomogeneous films in the absence of an external magnetic field is lower than for homogeneous ones. In turn, the critical magnetic field of inhomogeneous films is much larger than the critical field of homogeneous films.

Relaxed states of an ideal MHD plasma with external magnetic field

1995 ◽  
Vol 53 (3) ◽  
pp. 373-385 ◽  
Author(s):  
G. Knorr ◽  
M. Mond ◽  
C. Grabbe
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Vector Fields ◽  
Magnetic Energy ◽  
Adjoint Operator ◽  
Magnetic Helicity ◽  
Turbulent Transition ◽  
Ideal Mhd ◽  
Field Fluctuations ◽  
Base Vector

We study an ideal MHD plasma with the non-vanishing invariants energy, crosshelicity and magnetic helicity, confined in a cylinder with infinitely conducting walls and an externally applied magnetic field B0. The magnetic and velocity fields are expanded in base vector fields, satisfying Δ × Bλ = Bλ. Boundary conditions are imposed to make the curl a self-adjoint operator. The three invariants depend on the time-dependent coefficients of the base vector fields, and are used to construct the partition function to gather statistical information about the equlibrium thermodynamic state to which the plasma relaxes after a turbulent transition. For zero external magnetic field but large magnetic helicity, the energy resides preferentially in magnetic field fluctuations. A sizeable fraction of the kinetic energy initially present is transformed into magnetic energy. The energy condenses via an inverse cascade predominantly to the lowest energy eigenstate, in agreement with results obtained by Taylor. However, since we consider the whole spectrum of eigenstates, the energy does not exclusively occupy the lowest eigenstate. If the eigenvalues are densely spaced (as in a thin torus), the higher eigenmodes also contain appreciable amounts of energy, resulting in a finite pressure of the plasma. For constant and finite external magnetic field, the average induced magnetic field exactly cancels the external field. This indicates that, on a statistical average, the plasma is diamagnetic or superconducting. Superimposed on the average statistical state are fluctuations that may become large if the magnetic helicity is large.

Superconducting Tape-Shaped Wire by Y1Ba2cu3o7-δ with Jc ≈ 2000 A/cm2

1987 ◽  
Vol 99 ◽  
Author(s):  
S. Matsuda ◽  
M. Okada ◽  
T. Morimoto ◽  
T. Matsumoto ◽  
K. Ihara
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Superconducting Tape ◽  
Rolling Method ◽  
The Wire

ABSTRACTA tape-shaped wire with Y1 Ba2Cu3, O7-δ, core and Ag sheath was fabricated by a drawing-rolling method. The critical current density of the wire with 0.1 mm thickness and 6 mm width was in 2 the range of 2000 A/cm at 77 K in the absence of external magnetic field. Presence of 20 m Tesla magnetic field reduced the J value to 1/100.

Microwave Synthesis of Nano SiC Doping Mg(B1-2x(SiC)x)2 Superconductor and Superconductivity

2012 ◽  
Vol 512-515 ◽  
pp. 11-16
Author(s):  
Yuan Dong Peng ◽  
Qing Lin Xia ◽  
Qian Ming Huang ◽  
Li Ya Li ◽  
Hong Zhong Wang ◽  
...  
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Direct Synthesis ◽  
Xrd Analysis ◽  
Magnetization Measurement ◽  
Superconducting Transition ◽  
Short Time

Superconductor samples Mg(B1-2x(SiC)x)2 (x=0, 5%, 10%) are synthesized from nano SiC, Mg and amorphous boron powders by microwave direct synthesis in a short time. Powder X-ray diffraction (XRD) analysis indicates that the phases of the synthesis sample are MgB2 (major phase) and a small amount of MgO and Mg2Si. The main peaks of MgB2, (100), (101), (002) and (110) are shift to the higher diffraction angle position and the width of half height of the diffraction plane is broaden for the SiC doping Mg(B1-2x(SiC)x)2, which show that the B positions of MgB2 are partly substituted and the grains of MgB2 are fine. Scanning electron microscope (SEM) observation shows that the MgB2 grain size is very small and the sample is tightness (compact). The onset superconducting transition temperature of the Mg(B1-2x(SiC)x)2 (x=0, 5%, 10%) samples measured by magnetization measurement are about 37.6 K, 37.0 K, 36.8 K respectively. The critical current density Jc are calculated according to the Bean model from the magnetization hysteresis loop of the slab Mg(B1-2x(SiC)x)2 (x=0, 5%, 10%) samples. The critical current density Jc of nano SiC doping Mg(B1-2x(SiC)x)2 samples are greatly enhanced. In higher external magnetic field, the Jc of 10% SiC doped sample is the highest; in lower external magnetic field, the Jc of 5% SiC doped sample is the highest; while in the whole external magnetic field, the Jc of undoped sample is the lowest.

scholarly journals Current Density Distribution in 2G HTS Tape in an External Magnetic Field

2015 ◽  
Vol 67 ◽  
pp. 931-938 ◽  
Author(s):  
S.S. Fetisov ◽  
D.V. Sotnikov ◽  
S. Yu. Zanegin ◽  
N.V. Bykovsky ◽  
I.P. Radchenko ◽  
...  
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Density Distribution ◽  
Current Density ◽  
Current Density Distribution
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