A CONDUCTING PERMEABLE SPHERE IN THE PRESENCE OF A COIL CARRYING AN OSCILLATING CURRENT

1953 ◽  
Vol 31 (4) ◽  
pp. 670-678 ◽  
Author(s):  
James R. Wait
Keyword(s):  
Magnetic Fields ◽  
Magnetic Permeability ◽  
Scalar Potential ◽  
Spherical Body ◽  
Primary Field ◽  
Secondary Field ◽  
Electrical Prospecting ◽  
Permeable Sphere ◽  
A Current

The analysis is carried out for the problem of a current-carrying coil in the neighborhood of a spherical body whose conductivity and magnetic permeability differ from the surroundings. The case is considered in detail where the frequency is low enough so that the primary field of the coil can be derived from a magnetic scalar potential. The secondary magnetic fields due to the sphere are then derived. The "in-phase" and "quadrature" components of the secondary field are discussed numerically and illustrated by graphs. The results have application to electrical prospecting.

Measuring Magnetic Permeability of Monolithic Annular Measures in Alternating Magnetic Fields

2019 ◽  
Vol 55 (11) ◽  
pp. 851-857 ◽  
Author(s):  
V. A. Syas’ko ◽  
S. S. Golubev ◽  
Ya. G. Smorodinskii ◽  
P. V. Solomenchuk ◽  
E. B. Bryukhovetskaya
Keyword(s):  
Magnetic Fields ◽  
Magnetic Permeability ◽  
Alternating Magnetic Fields

Dynamic vortex Mott transition in triangular superconducting arrays

2021 ◽  
Author(s):  
Pei Zi-Xi ◽  
Guo Wei-Gui ◽  
Qiu Xiang-Gang
Keyword(s):  
Magnetic Fields ◽  
Differential Resistance ◽  
Mott Transition ◽  
Top Down ◽  
Au Film ◽  
Magnetic Flux Quantum ◽  
Universality Classes ◽  
Potential Landscape ◽  
Superconducting Arrays ◽  
A Current

Abstract The proximity-coupled superconducting island arrays on a metallic film provide an ideal platform to study the phase transition of vortex states under mutual interactions between the vortex and potential landscape. We have developed a top-down microfabrication process for Nb island arrays on Au film by employing an Al hard mask. A current-induced dynamic vortex Mott transition has been observed under the perpendicular magnetic fields of $f$ magnetic flux quantum per unit cell, which is characterized by a dip-to-peak reversal in differential resistance $dV/dI$ vs. $f$ curve with the increasing current. The $dV/dI$ vs. $I$ characteristics show a scaling behavior near the magnetic fields of $f=\frac{1}{2}$ and $f=1$, with the critical exponents $\varepsilon$ of 0.45 and 0.3 respectively, suggesting different universality classes at these two fields.

Statistics on Jupiter's Current Sheet with Juno Data: Geometry, Magnetic Fields and Energetic Particles

2021 ◽  
Author(s):  
Zhi-Yang Liu ◽  
Qiu-Gang Zong ◽  
Michel Blanc
Keyword(s):  
Magnetic Fields ◽  
Current Sheet ◽  
Power Law ◽  
Heavy Ions ◽  
Particle Interaction ◽  
The Other ◽  
Gaussian Functions ◽  
Fixed Energy ◽  
Thin Current Sheet ◽  
A Current

<p>Jupiter's magnetosphere contains a current sheet of huge size near its equator. The current sheet not only mediates the global mass and energy cycles of Jupiter's magnetosphere, but also provides an occurring place for many localized dynamic processes, such as reconnection and wave-particle interaction. To correctly evaluate its role in these processes, a statistical description of the current sheet is required. To this end, here we conduct statistics on Jupiter's current sheet, with four-year Juno data recorded in the 20-100 Jupiter radii, post-midnight magnetosphere. The results suggest a thin current sheet whose thickness is comparable with the gyro-radius of dominant ions. Magnetic fields in the current sheet decrease in power-law with increasing radial distances. At fixed energy, the flux of electrons and protons increases with decreasing radial distances. On the other hand, at fixed radial distances, the flux decreases in power-law with increasing energy. The flux also varies with the distances to the current sheet center. The corresponding relationship can be well described by Gaussian functions peaking at the current sheet center. In addition, the statistics show the flux of oxygen- and sulfur-group ions is comparable with the flux of protons at the same energy and radial distances, indicating the non-negligible effects of heavy ions on current sheet dynamics. From these results, a statistical model of Jupiter's current sheet is constructed, which provides us with a start point of understanding the dynamics of the whole Jupiter's magnetosphere.</p>

Static magnetic fields in vacuum

2018 ◽  
Author(s):  
J. Pierrus
Keyword(s):  
Magnetic Field ◽  
Problem Solving ◽  
Magnetic Fields ◽  
Vector Potential ◽  
Scalar Potential ◽  
Multipole Expansion ◽  
Magnetic Vector Potential ◽  
Magnetic Dipoles ◽  
Static Magnetic Fields ◽  
The Magnetic Field

Wherever possible, an attempt has been made to structure this chapter along similar lines to Chapter 2 (its electrostatic counterpart). Maxwell’s magnetostatic equations are derived from Ampere’s experimental law of force. These results, along with the Biot–Savart law, are then used to determine the magnetic field B arising from various stationary current distributions. The magnetic vector potential A emerges naturally during our discussion, and it features prominently in questions throughout the remainder of this book. Also mentioned is the magnetic scalar potential. Although of lesser theoretical significance than the vector potential, the magnetic scalar potential can sometimes be an effective problem-solving device. Some examples of this are provided. This chapter concludes by making a multipole expansion of A and introducing the magnetic multipole moments of a bounded distribution of stationary currents. Several applications involving magnetic dipoles and magnetic quadrupoles are given.

Estimation and geologic interpretation of regolith chargeability and superparamagnetic susceptibility in airborne electromagnetic data

Geophysics ◽  
2020 ◽  
Vol 85 (5) ◽  
pp. E153-E162 ◽  
Author(s):  
James Macnae ◽  
Tim Munday ◽  
Camilla Soerensen
Keyword(s):  
Magnetic Permeability ◽  
Thin Sheet ◽  
Secondary Field ◽  
Conductivity Model ◽  
Electromagnetic Data ◽  
Delay Times ◽  
Airborne Electromagnetic ◽  
Geologic Interpretation ◽  
Airborne Electromagnetic Data ◽  
Dispersive Models

All available inversion software for airborne electromagnetic (AEM) data can at a minimum fit a nondispersive conductivity model to the observed inductive secondary field responses, whether operating in the time or frequency domain. Quasistatic inductive responses are essentially controlled by the induction number, the product of frequency with conductivity and magnetic permeability. Recent research has permitted the conductivity model to be dispersive, commonly using a single Cole-Cole parameterization of the induced polarization (IP) effect; but this parameterization slows down and destabilizes any inversion, and it does not account for the need for dual or multiple Cole-Cole responses. Little has been published on inverting AEM data affected by frequency-dependent magnetic permeability, or superparamagnetism (SPM), usually characterized by a Chikazumi model. Because the IP and SPM effects are small and are usually only obvious at late delay times, the aim of our research is to determine if these IP and SPM effects can be fitted and stripped from the AEM data after being approximated with simple dispersive models. We are able to successfully automate a thin-sheet model to do this stripping. Stripped data then can be inverted using a nondispersive conductivity model. The IP and SPM parameters fitted independently to each independent measured decay to provide stripping are proven to be spatially coherent, and they are geologically sensible. The results are found to enhance interpretation of the regolith geology, particularly the nature and distribution of transported materials that are not afforded by mapping conductivity/conductance alone.

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