INHOMOGENEOUS CYLINDRICAL ORE BODY IN PRESENCE OF A TIME VARYING MAGNETIC FIELD

Geophysics ◽  
1962 ◽  
Vol 27 (3) ◽  
pp. 386-392 ◽  
Author(s):  
Janardan G. Negi
Keyword(s):  
Magnetic Field ◽  
Magnetic Permeability ◽  
Propagation Constant ◽  
Homogeneous Medium ◽  
Step Function ◽  
Practical Case ◽  
Time Varying ◽  
Geophysical Prospecting ◽  
The Core ◽  
Ore Body

The secondary fields are evaluated for the case of an inhomogeneous conducting cylinder embedded in an infinite homogeneous medium under the influence of a time varying magnetic field. Both sinusoidal and step function responses are studied in detail for a practical case of interest in geophysical prospecting in which the exterior medium is relatively poorly conducting, the propagation constant in the cylinder is varying linearly across the section of the core, and the magnetic permeability is the same everywhere.

A CONDUCTING SPHERE IN A TIME VARYING MAGNETIC FIELD

Geophysics ◽  
1951 ◽  
Vol 16 (4) ◽  
pp. 666-672 ◽  
Author(s):  
James R. Wait
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Eddy Currents ◽  
Transient Behavior ◽  
Step Function ◽  
Conducting Medium ◽  
Time Varying ◽  
Geophysical Prospecting ◽  
Conducting Sphere

The secondary magnetic fields are evaluated for the case of a conducting sphere in a relatively poorly conducting medium under the influence of a time varying magnetic field. The sinusoidal and step function responses are both considered. The responses so calculated are thought to be useful in a geophysical prospecting method which utilizes the transient behavior of induced eddy currents in a highly conducting ore zone.

The recent secular variation and the motions at the core surface

1982 ◽  
Vol 306 (1492) ◽  
pp. 271-280 ◽  
Keyword(s):  
Magnetic Field ◽  
Time Derivative ◽  
Step Function ◽  
Second Derivative ◽  
Firm Conclusion ◽  
The Core ◽  
Drift Term ◽  
The Magnetic Field ◽  
Westward Drift ◽  
Magnetic Observatories

The Earth’s magnetic field has been undergoing a remarkably systematic variation during the last 30 years. This variation can be described by a constant time derivative and a step-function second derivative. These parameters are smoothly distributed over the Earth’s surface. The step occurred in 1969 and caused the second derivative to change signs for all of the components at most of the magnetic observatories. Similar but less well documented behavior had been observed around 1900; it seemed to correlate with a jump in the acceleration of the Earth’s rotation. We have investigated the motions at the top of the Earth’s core that are responsible for the recent magnetic variations by inversion procedures. The motions responsible for the time derivative of the magnetic field can be reasonably well assessed and are dominated by a westward drift term of approximately 0.2°/year, although important poloidal motions are also inferred. The data for the jump in the second derivative are much noisier and the motion accelerations are not as well resolved. The poloidal acceleration terms are still fairly well resolved, but the toroidal motions, especially the zonal motions, are very poorly resolved. No firm conclusion about an acceleration of the westward drift can be given on the basis of this analysis. The inversions give evidence that the motions for the lower modes are a strongly decreasing function of their order.

scholarly journals Time-like detonation in presence of magnetic field

2019 ◽  
Vol 37 (01) ◽  
pp. 30-37
Author(s):  
Shailendra Singh ◽  
Ritam Mallick
Keyword(s):  
Magnetic Field ◽  
Inertial Confinement Fusion ◽  
Gluon Plasma ◽  
High Energy ◽  
Inertial Confinement ◽  
Time Varying ◽  
Continuous Transition ◽  
The Core ◽  
Confinement Fusion ◽  
Sinusoidal Magnetic Field

AbstractWe study the effect of magnetic field in an implosion process achieved by radiation. A time-varying sinusoidal magnetic field is seen to affect the continuous transition of space-like detonation to time-like detonation at the core of implosion region. The oscillating varying magnetic field has a significant effect in increasing the volume of the time-like detonation of the core of implosion and also modifies the time of the implosion process. This transition can have significant outcome both theoretically and experimentally in the areas of high-energy hadronization of quark–gluon plasma matter and inertial confinement fusion efforts of fuels.

Transient fields for an electric dipole in a dissipative medium

1970 ◽  
Vol 48 (16) ◽  
pp. 1858-1862 ◽  
Author(s):  
James R. Wait ◽  
Kenneth P. Spies
Keyword(s):  
Magnetic Field ◽  
Dielectric Constant ◽  
Electric Dipole ◽  
Homogeneous Medium ◽  
Step Function ◽  
Dissipative Medium ◽  
Electric And Magnetic Field ◽  
Displacement Currents ◽  
Explicit Expressions

Explicit expressions are presented for the electric and magnetic field components of a step-function excited electric dipole immersed in an infinite homogeneous medium with a specified conductivity and dielectric constant. It is shown that displacement currents influence only the early part of the waveform.

CONTINUATION OF ELECTROMAGNETIC FIELDS—I

Geophysics ◽  
1968 ◽  
Vol 33 (5) ◽  
pp. 834-837 ◽  
Author(s):  
Amalendu Roy
Keyword(s):  
Electromagnetic Fields ◽  
Propagation Constant ◽  
Homogeneous Medium ◽  
Spherical Geometry ◽  
Theoretical Problem ◽  
Practical Case ◽  
Spatial Frequencies ◽  
Analysis And Synthesis ◽  
Space Frequency ◽  
Spectral Analysis And Synthesis

This note examines the theoretical problem of continuation of electromagnetic fields by the method of spectral analysis and synthesis, without making any restricting assumptions in regard to the conductivity of the medium and the frequency of the field. It is found that the space frequency spectrum of the continued field at a level z is obtained by multiplying that of the observed field on z=0 by exp (±θz), where [Formula: see text], [Formula: see text] and [Formula: see text] are the spatial frequencies in two orthogonal directions and k is the propagation constant. For spherical geometry, the expansion of the observed field needs to be done in terms of spherical harmonics, and the multiplying factors for inward and outward continuation are, respectively, [Formula: see text] and [Formula: see text] where J and H are Bessel functions, r is the radius of sphere of continuation and a is the radius of the sphere of observation. While the method is valid for continuation in air or inside a homogeneous medium, it fails in the more practical case when one wants to continue inside an inhomogeneous earth. This is because, in certain regions of an in homogeneous earth, the field consists of two unknown parts, one of which increases with z or r while the other decreases.

Investigation of the Structure and Magnetic Properties of Bulk Amorphous FeCoYB Alloy

2017 ◽  
Vol 68 (9) ◽  
pp. 2162-2165 ◽  
Author(s):  
Katarzyna Bloch ◽  
Mihail Aurel Titu ◽  
Andrei Victor Sandu
Keyword(s):  
Magnetic Field ◽  
Magnetic Properties ◽  
Hyperfine Field ◽  
Irreversible Processes ◽  
Magnetization Process ◽  
Casting Method ◽  
The Core ◽  
Injection Casting ◽  
Core Losses ◽  
Microstructural Studies

The paper presents the results of structural and microstructural studies for the bulk Fe65Co10Y5B20 and Fe63Co10Y7B20 alloys. All the rods obtained by the injection casting method were fully amorphous. It was found on the basis of analysis of distribution of hyperfine field induction that the samples of Fe65Co10Y5B20 alloy are characterised with greater atomic packing density. Addition of Y to the bulk amorphous Fe65Co10Y5B20 alloy leads to the decrease of the average induction of hyperfine field value. In a strong magnetic field (i.e. greater than 0.4HC), during the magnetization process of the alloys, where irreversible processes take place, the core losses associated with magnetization and de-magnetization were investigated.

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