ANALOGUE MODEL MEASUREMENTS FOR ELECTROMAGNETIC VARIATIONS NEAR A COASTLINE

1966 ◽  
Vol 3 (7) ◽  
pp. 917-936 ◽  
Author(s):  
H. W. Dosso
Keyword(s):  
Magnetic Field ◽  
Vertical Magnetic Field ◽  
Analogue Model ◽  
Conducting Zone

An analogue model for studying the behavior of the natural geomagnetic and telluric field variations for the coastline problem is discussed. Measurements of amplitudes and phases for the horizontal electric, the horizontal magnetic, and the vertical magnetic field components for sloping earth–sea interfaces and for a sea over an upwelling conducting zone within the mantle in the form of a step are discussed for both the E and the H polarizations.

ANALOGUE MODEL MEASUREMENTS FOR ELECTROMAGNETIC VARIATIONS NEAR VERTICAL FAULTS AND DYKES

1966 ◽  
Vol 3 (3) ◽  
pp. 287-303 ◽  
Author(s):  
H. W. Dosso
Keyword(s):  
Magnetic Field ◽  
Vertical Magnetic Field ◽  
Geological Structures ◽  
Analogue Model

An analogue model for studying the behavior of the natural geomagnetic and telluric field variations for various geological structures is described. Measurements of amplitudes and phases for the horizontal electric, the horizontal magnetic, and the vertical magnetic field components are obtained and discussed for various conducting vertical faults and dykes for both the H and the E polarizations.

Analogue model measurements of electromagnetic variations in the near field of an oscillating line current

1968 ◽  
Vol 5 (1) ◽  
pp. 23-29 ◽  
Author(s):  
H. W. Dosso ◽  
J. A. Jacobs
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Current Model ◽  
Near Field ◽  
Analogue Model ◽  
Line Current ◽  
Earth’S Mantle ◽  
Electric And Magnetic Fields ◽  
Sheet Current ◽  
Conducting Zone

An analogue model for studying electromagnetic variations for an overhead oscillating line current is described. Measurements of electric and magnetic fields for model earth–sea interfaces are discussed and compared with results reported earlier for an overhead sheet current. A truncated cone representing a circular sea, a graphite wedge representing an ocean coastline, and a graphite wedge underlain by a graphite block representing an upwelling conducting zone in the earth's mantle near a sea coast are considered. In some cases the results for the line current model differ appreciably from those for the sheet current model, indicating that the nature of the source field can be an important factor in determining the behavior of the field components. The model measurements indicate that land–sea interfaces produce no appreciable anomalous magnetic fields at frequencies below 0.01 cps and hence the presence of the sea alone cannot account for coastal magnetic field anomalies. The results obtained for the model coastline structures tend to support the idea put forth by various workers that experimentally observed coastal magnetic field anomalies can in some cases be explained by assuming an upwelling conducting zone within the earth's mantle.

scholarly journals Overstable rotating convection in the presence of a vertical magnetic field

2021 ◽  
Vol 33 (3) ◽  
pp. 034130
Author(s):  
Ankan Banerjee ◽  
Manojit Ghosh ◽  
Lekha Sharma ◽  
Pinaki Pal
Keyword(s):  
Magnetic Field ◽  
Vertical Magnetic Field ◽  
Rotating Convection

Effects of a Vertical Magnetic Field on Particle Confinement in a Magnetized Plasma Torus

2004 ◽  
Vol 93 (16) ◽  
Author(s):  
S. H. Müller ◽  
A. Fasoli ◽  
B. Labit ◽  
M. McGrath ◽  
M. Podestà ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetized Plasma ◽  
Vertical Magnetic Field ◽  
Plasma Torus ◽  
Particle Confinement

Effect of magnetic field on parametrically driven surface waves

2006 ◽  
Vol 463 (2079) ◽  
pp. 711-722 ◽  
Author(s):  
Supriyo Paul ◽  
Krishna Kumar
Keyword(s):  
Magnetic Field ◽  
Surface Waves ◽  
Liquid Metals ◽  
Tricritical Point ◽  
Thin Layers ◽  
Vertical Magnetic Field ◽  
Harmonic Solution ◽  
Chandrasekhar Number ◽  
The Magnetic Field ◽  
Primary Instability

Stability analysis of parametrically driven surface waves in liquid metals in the presence of a uniform vertical magnetic field is presented. Floquet analysis gives various subharmonic and harmonic instability zones. The magnetic field stabilizes the onset of parametrically excited surface waves. The minima of all the instability zones are raised by a different amount as the Chandrasekhar number is raised. The increase in the magnetic field leads to a series of bicritical points at a primary instability in thin layers of a liquid metal. The bicritical points involve one subharmonic and another harmonic solution of different wavenumbers. A tricritical point may also be triggered as a primary instability by tuning the magnetic field.

scholarly journals ELECTROMAGNETIC FIELDS OF CHARGED AND MAGNETIZED CYLINDRICAL CONDUCTORS IN NUT SPACE

2005 ◽  
Vol 14 (03n04) ◽  
pp. 687-695 ◽  
Author(s):  
B. J. AHMEDOV ◽  
A. V. KHUGAEV ◽  
N. I. RAKHMATOV
Keyword(s):  
Magnetic Field ◽  
Gravitational Field ◽  
Electromagnetic Fields ◽  
Electric Charge ◽  
Maxwell Equations ◽  
Analytic Solutions ◽  
Vertical Magnetic Field ◽  
General Relativistic ◽  
Azimuthal Current ◽  
Cylindrical Conductors

We present analytic solutions of Maxwell equations for infinitely long cylindrical conductors with nonvanishing electric charge and currents in the external background spacetime of a line gravitomagnetic monopole. It has been shown that vertical magnetic field arising around cylindrical conducting shell carrying azimuthal current will be modified by the gravitational field of NUT source. We obtain that the purely general relativistic magnetic field which has no Newtonian analog will be produced around charged gravitomagnetic monopole.

The Thermal-Convective Instability in a Stellar Atmosphere with Rotation and Hall Effects

1974 ◽  
Vol 29 (6) ◽  
pp. 867-869 ◽  
Author(s):  
R. C. Sharma
Keyword(s):  
Magnetic Field ◽  
Convective Instability ◽  
Stellar Atmosphere ◽  
Vertical Magnetic Field ◽  
Hall Effects ◽  
Monotonic Instability

The problem of thermal-convective instability of a stellar atmosphere is considered to include the effects due to rotation and Hall currents in the presence of a uniform vertical magnetic field The criterion for monotonic instability is found to be unchanged by the presence of rotation and Hall effects.

scholarly journals Properties of the inner penumbral boundary and temporal evolution of a decaying sunspot

2018 ◽  
Vol 620 ◽  
pp. A191 ◽  
Author(s):  
M. Benko ◽  
S. J. González Manrique ◽  
H. Balthasar ◽  
P. Gömöry ◽  
C. Kuckein ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Flux ◽  
Temporal Evolution ◽  
Vertical Component ◽  
Field Vector ◽  
Linear Increase ◽  
Vertical Magnetic Field ◽  
Magnetic Diffusion ◽  
The Magnetic Field ◽  
Linear Decay

Context. It has been empirically determined that the umbra-penumbra boundaries of stable sunspots are characterized by a constant value of the vertical magnetic field. Aims. We analyzed the evolution of the photospheric magnetic field properties of a decaying sunspot belonging to NOAA 11277 between August 28–September 3, 2011. The observations were acquired with the spectropolarimeter on-board of the Hinode satellite. We aim to prove the validity of the constant vertical magnetic-field boundary between the umbra and penumbra in decaying sunspots. Methods. A spectral-line inversion technique was used to infer the magnetic field vector from the full-Stokes profiles. In total, eight maps were inverted and the variation of the magnetic properties in time were quantified using linear or quadratic fits. Results. We find a linear decay of the umbral vertical magnetic field, magnetic flux, and area. The penumbra showed a linear increase of the vertical magnetic field and a sharp decay of the magnetic flux. In addition, the penumbral area quadratically decayed. The vertical component of the magnetic field is weaker on the umbra-penumbra boundary of the studied decaying sunspot compared to stable sunspots. Its value seem to be steadily decreasing during the decay phase. Moreover, at any time of the sunspot decay shown, the inner penumbra boundary does not match with a constant value of the vertical magnetic field, contrary to what is seen in stable sunspots. Conclusions. During the decaying phase of the studied sunspot, the umbra does not have a sufficiently strong vertical component of the magnetic field and is thus unstable and prone to be disintegrated by convection or magnetic diffusion. No constant value of the vertical magnetic field is found for the inner penumbral boundary.

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