scholarly journals DIFFUSION FROM A LINE SOURCE IN A MAGNETIC FIELD

1963 ◽  
Author(s):  
K Berkner ◽  
R Pyle ◽  
H Rugge ◽  
J Stearns ◽  
J Winocur
Keyword(s):  
Magnetic Field ◽  
Line Source

RADIATION FROM A LINE SOURCE IN A UNIAXIALLY ANISOTROPIC PLASMA

1963 ◽  
Vol 41 (2) ◽  
pp. 246-257 ◽  
Author(s):  
H. S. Tuan ◽  
S. R. Seshadri
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Line Source ◽  
Plasma Frequency ◽  
Angular Spectrum ◽  
Radiation Characteristics ◽  
Magnetic Current ◽  
Line Charge ◽  
Unit Path Length ◽  
Moving Line

Two problems of radiation in a magnetized, incompressible plasma are investigated. The radiation characteristics of a line source of magnetic current are studied for the case in which the external magnetic field is infinite and oriented in a direction perpendicular to that of the source. The second problem that is treated is the radiation from a uniformly moving line charge. Two cases are considered, namely: (1) when the motion of the line charge is parallel and (2) when it is perpendicular to the direction of the external magnetic field. In each case it is found that there is a Cerenkov-type radiation for frequencies less than the plasma frequency. The frequency and the angular spectrum, as well as the total energy radiated per unit path length, are determined for both cases.

ELECTROMAGNETIC SCATTERING BY CONDUCTORS IN THE EARTH NEAR A LINE SOURCE OF CURRENT

Geophysics ◽  
1971 ◽  
Vol 36 (1) ◽  
pp. 101-131 ◽  
Author(s):  
Gerald W. Hohmann
Keyword(s):  
Magnetic Field ◽  
Half Space ◽  
Line Source ◽  
Numerical Technique ◽  
The Body ◽  
Scale Model ◽  
Electromagnetic Response ◽  
Field Phase ◽  
Horizontal Magnetic Field ◽  
Depth Of Burial

A theoretical solution is developed for the electromagnetic response of a two‐dimensional inhomogeneity in a conductive half‐space, in the field of a line source of current. The solution is in the form of an integral equation, which is reduced to a matrix equation, and solved numerically for the electric field in the body. The electric and magnetic fields at the surface of the half‐space are found by integrating the half‐space Green’s functions over the scattering currents. One advantage of this particular numerical technique is that it is necessary to solve for scattering currents only in the conductor and not throughout the half‐space. The response of a thin, vertical conductor is studied in some detail. Because the only interpretational aids available previously were scale model results for conductors in free space, the results presented here should be useful in interpreting data and in designing new EM systems. As expected, anomalies decay rapidly as depth of burial is increased, due to attenuation in the conductive half‐space. Depth of exploration appears to be greatest for measurements of horizontal magnetic field phase, while vertical field phase is diagnostic of conductivity. Horizontal location and depth of burial are best determined through measurements of vertical or horizontal magnetic field amplitude.

scholarly journals The Structure of a Stream of Electrons and Ions Drifting and Diffusing in a Gas When Ionization by Collision and Molecular Attachment are Present

1959 ◽  
Vol 12 (2) ◽  
pp. 171 ◽  
Author(s):  
LGH Huxley
Keyword(s):  
Magnetic Field ◽  
Point Source ◽  
Line Source ◽  
Electron Attachment ◽  
Uniform Field ◽  
Electrons And Ions

The theory is developed of the structure of a stream of electrons and ions drifting under the action of a uniform field and diffusing in a gas when either or both ionization by collision and electron attachment are present. The cases considered include a point source and a line source, and in the latter case the influence of a magnetic field is discussed.

RADIATION FROM A SOURCE NEAR A PLANE INTERFACE BETWEEN AN ISOTROPIC AND A GYROTROPIC DIELECTRIC

1964 ◽  
Vol 42 (11) ◽  
pp. 2153-2172 ◽  
Author(s):  
S. R. Seshadri ◽  
A. Hessel
Keyword(s):  
Magnetic Field ◽  
Electromagnetic Field ◽  
Surface Waves ◽  
High Frequency ◽  
Free Space ◽  
Line Source ◽  
Low Frequency ◽  
Plane Interface ◽  
Magnetic Current ◽  
Asymptotic Evaluation

The radiation from a line source of magnetic current situated in free space near a plane interface between a semi-infinite free space and a semi-infinite gyrotropic dielectric is investigated for the case in which the gyrotropic axis is parallel to the line source. In addition to the space waves, it is found that in general two unidirectional surface waves are excited along the interface. The dispersion relations for the space and the surface waves are thoroughly examined. Both surface waves have different high-frequency cutoff but no low-frequency cutoff. The characteristics of these surface waves are investigated. An asymptotic evaluation of the total electromagnetic field is carried out for a particularly simple choice of the source frequency. For this frequency, the dependence of the efficiency of excitation of the surface waves on the distance of the source from the interface is determined. The radiation patterns are plotted for various values of the static magnetic field and the position of the source.

Guided propagation of Alfvén waves in the magnetosphere

1967 ◽  
Vol 1 (4) ◽  
pp. 387-406 ◽  
Author(s):  
J. A. Fejer ◽  
Kaifong Lee
Keyword(s):  
Magnetic Field ◽  
Line Source ◽  
Cold Plasma ◽  
Alfven Waves ◽  
Alfvén Waves ◽  
Finite Width ◽  
Radiated Power ◽  
Points Of View ◽  
Guided Propagation ◽  
The Magnetic Field

The guided propagation of Alfvén waves in a cold plasma is discussed from several points of view. First the field of a line source is calculated at infinity. This calculation leads to a divergence in the radiated power in two directions forming very small angles with the magnetic field.The divergence is removed if the line source is replaced by a strip source of finite width. It is shown that propagation from a strip source only a few kilo-metres wide is strongly guided by the magnetic field, with almost no spreading, along a field line extending up to, say, 4 earth radii for wave periods of about 100 sec.

scholarly journals The Effect of Remanent Magnetization on Aeromagnetic Interpretation

1957 ◽  
Vol 10 (4) ◽  
pp. 547 ◽  
Author(s):  
DJ Sutton ◽  
WG Mumme
Keyword(s):  
Magnetic Field ◽  
Dipole Moment ◽  
Line Source ◽  
Remanent Magnetization ◽  
Point Dipole ◽  
Earth’S Magnetic Field ◽  
Plane Normal ◽  
Earth's Magnetic Field

The interpretation of aeromagnetic maps when the source may be approximated to a point dipole or line of dipoles is considered for the general case in which the dipole moment is not necessarily parallel to the Earth's magnetic field. For the line of dipoles, it is shown that even in this general case the depth and location of the source can be found, and in addition the direction of the component of the dipole moment in a plane normal to the line source may be determined. If the K�nigsberger ratio for the rock constituting the source is large, this is approximately the direction of the remanent magnetization. Such information is important from a palaeomagnetic viewpoint. When the source approximates closely to a point dipole, it is not possible both to locate the source and determine the direction of the dipole moment from an analysis of the aeromagnetic map and the solution of the problem requires further information.

THE ELECTROMAGNETIC FIELDS OF A SUBTERRANEAN CYLINDRICAL INHOMOGENEITY EXCITED BY A LINE SOURCE

Geophysics ◽  
1972 ◽  
Vol 37 (6) ◽  
pp. 975-984 ◽  
Author(s):  
Allen Q. Howard
Keyword(s):  
Magnetic Field ◽  
Integral Equation ◽  
Line Source ◽  
Field Amplitude ◽  
Two Dimensional ◽  
Vertical Magnetic Field ◽  
Geophysical Prospecting ◽  
Field Phase ◽  
Horizontal Magnetic Field ◽  
Mine Rescue

The anomalous fields from a buried cylindrical inhomogeneity in an otherwise uniform half‐space are analyzed. The problem is rendered two‐dimensional by assuming that the uniform line source of current is parallel to the subsurface cylinder. The multipole scattered field coefficients are obtained from the numerical solution to the associated singular Fredholm integral equation of the second kind. The horizontal magnetic field amplitude, the vertical magnetic field phase, and the amplitude and phase of the ratio of horizontal to vertical magnetic fields are shown to be diagnostic of the location of the inhomogeneity. The results have possible applications to electromagnetic location in mine rescue operations and to geophysical prospecting.

Electromagnetic radiation from line sources embedded in a moving bounded magnetoplasma sheath

1977 ◽  
Vol 17 (2) ◽  
pp. 171-184 ◽  
Author(s):  
P. K. Mukherjee
Keyword(s):  
Magnetic Field ◽  
Electromagnetic Radiation ◽  
Line Source ◽  
Plasma Sheath ◽  
Magnetic Line ◽  
Conducting Plane ◽  
Radiation Fields ◽  
Electric Line ◽  
Moving Plasma ◽  
The Magnetic Field

The problem of electromagnetic radiation from electric and magnetic line sources embedded in a moving bounded magrietoplasma sheath situated over a perfectly conducting plane is studied. The radiation fields due to the line sources consist of both E and H modes, excited simultaneously in the moving sheath. However, when the magnetic field lies parallel to the line source and is oriented normal to the direction of the sheath motion, the modes become decoupled. The far-zone radiation fields for both the electric and the magnetic line sources have been obtained, using the method of saddle-point approximation. The corresponding radiation patterns are also obtained and their variation studied as a function of the magnetic field, the location of the line source, the thickness and the velocity of the moving plasma sheath. It is found that the fields radiated by an electric line source remain unaffected by the presence of an ambient magnetic field and that, in the presence of a sufficiently intense magnetizing field, the magnetic line source over a perfectly conducting plane radiates as though surrounded by vacuum.

scholarly journals Steady Natural Convection Heat and Mass Transfer Due to a Horizontal Line Source in the Presence Of Magnetic Field and Chemical Reaction

2018 ◽  
Vol 7 (3.31) ◽  
pp. 168
Author(s):  
Venkat Rao Kanuri ◽  
Sridevi Dandu ◽  
Santhi Gottumukkala ◽  
Nagubabeswara Rao Cheemalapati
Keyword(s):  
Magnetic Field ◽  
Mass Transfer ◽  
Prandtl Number ◽  
Chemical Reaction ◽  
Line Source ◽  
Schmidt Number ◽  
Horizontal Line ◽  
Transport Parameters ◽  
Centre Line ◽  
Plume Flow

Natural convective heat and mass transfer due to a horizontal line source at an adiabatic plate and plane plume flow are analyzed in the presence of magnetic field and chemical reaction. The case of an isothermal plate and a plate of varying temperature are also discussed. Certain qualitatively distinct behaviours of the transport parameters noticed are - for an adiabatic plate as well as an isothermal plate, the transport parameters have exhibited asymptotic behaviour with the Prandtl number and Schmidt number. For Plume flow centre line velocity has exhibited asymptotic behaviour with Prandtl number and Schmidt number. Transport parameters diminished but centre line velocity of the Plume increased with increasing magnetic field. Chemical reaction is seen to increase centre line velocity/Sherwood number and diminish skin friction/Nusselt number. Comparison of the results at an adiabatic plate with those at an isothermal plate and a plate of varying temperature is made.       

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