Transformation of VLF anomaly maps into apparent resistivity and phase

Geophysics ◽  
2003 ◽  
Vol 68 (2) ◽  
pp. 497-505 ◽  
Author(s):  
Michael Becken ◽  
Laust B. Pedersen
Keyword(s):  
Magnetic Field ◽  
Plane Wave ◽  
Electric Field ◽  
Transfer Functions ◽  
Magnetic Data ◽  
Impedance Tensor ◽  
Wave Source ◽  
Layered Earth ◽  
Magnetic Transfer ◽  
The Magnetic Field

We investigate a transformation of magnetic transfer functions into the tangential‐electric mode part of the impedance tensor in the scope of the plane‐wave electromagnetic tensor–VLF method. The transformation, which is applicable to any 2D data representing the response of arbitrary 3D geoelectric structures, overcomes the difficulties of quantitative interpretation of magnetic transfer functions, which predominantly provide a measure of the lateral changes of the electrical conductivity in the earth. We require densely sampled magnetic transfer functions of one frequency as input data. These may be decomposed into their normal and anomalous parts (deviation from the response of a layered earth) for a unit external plane‐wave source field using the Hilbert transform relationship between the magnetic field components. Faraday's law then directly provides the anomalous toroidal electric field. Unfortunately, there is no chance to estimate the normal electric field from magnetic data, since the magnetic field is not sensitive to a layered earth. This constant must be provided as a boundary condition, e.g., from one ground measurement, to derive an impedance tensor and related apparent resistivities and phases.

THE TELLURIC‐MAGNETOTELLURIC METHOD

Geophysics ◽  
1975 ◽  
Vol 40 (4) ◽  
pp. 664-668 ◽  
Author(s):  
John F. Hermance ◽  
Richard E. Thayer
Keyword(s):  
Magnetic Field ◽  
Electric Field ◽  
Complex Impedance ◽  
Magnetic Data ◽  
Impedance Tensor ◽  
Combined Method ◽  
Remote Site ◽  
Base Site ◽  
Magnetotelluric Method ◽  
The Magnetic Field

The telluric‐magnetotelluric method uses magnetotelluric measurements at the base site, but only telluric measurements at remote sites. It thus combines the economy, simplicity, and speed of the traditional telluric method with the quantitative advantages of the traditional magnetotelluric method. The dominant features of the combined method are the following: First, the time required to set up a telluric site is less by a factor of at least 5 than the time for a complete magnetotelluric site. Second, one does not need to record magnetic field data at the base site simultaneously with the electric field recorded at each remote site. One needs only enough magnetic data to adequately determine the base tensor. A telluric transfer tensor coupling electric field measurements at the base site and each remote site can be used to transfer the base impedance tensor to an impedance tensor at each remote site. By being much more selective of the magnetic data used in the analysis, one can significantly improve the signal‐to‐noise ratio. Third, the data are analyzed to determine each element of the complex impedance tensor so that important phase information as well as amplitude information is available for interpretations which are more sophisticated than those currently attempted in conventional telluric surveys. Finally, in making the ultimate interpretation in terms of the impedance tensor rather than the telluric tensor used in conventional telluric surveys, one essentially refers the interpretation of remote electric field observations to the magnetic field at the base site rather than to the electric field. Both experience and model studies demonstrate that the magnetic field is much more homogeneous than the electricfield in the vicinity of lateral heterogeneities; thus the selection of a proper base site is not as critical in the combined method as it is in the conventional telluric method.

Seismoelectric wave conversions in porous media: Field measurements and transfer function analysis

Geophysics ◽  
2001 ◽  
Vol 66 (5) ◽  
pp. 1417-1430 ◽  
Author(s):  
Stéphane Garambois ◽  
Michel Dietrich
Keyword(s):  
Magnetic Field ◽  
Dielectric Constant ◽  
Electric Field ◽  
Electric Fields ◽  
Field Experiments ◽  
Transfer Functions ◽  
Function Analysis ◽  
Transfer Function Analysis ◽  
Electromagnetic Disturbances ◽  
The Magnetic Field

We present a series of field experiments showing the transient electric fields generated by a seismic excitation of the subsurface. After removing the powerline noise by adaptive filtering, the most prominent feature of the seismoelectric recordings is the presence of electric signals very similar to conventional seismic recordings. In one instance, we identified small‐amplitude precursory electromagnetic disturbances showing a polarity reversal on either side of the shotpoint. Concentrating on the dominant seismoelectric effect, we theoretically show that the electric field accompanying the compressional waves is approximately proportional to the grain acceleration. We also demonstrate that the magnetic field moving along with shear waves is roughly proportional to the grain velocity. These relationships hold true as long as the displacement currents are much smaller than the conduction currents (diffusive regime), which is normally the case in the low‐frequency range used in seismic prospecting. Furthermore, the analytical transfer functions thus obtained indicate that the electric field is mainly sensitive to the salt concentration and dielectric constant of the fluid, whereas the magnetic field principally depends on the shear modulus of the framework of grains and on the fluid’s viscosity and dielectric constant. Both transfer functions are essentially independent of the permeability. Our results suggest that the simultaneous recording of seismic, electric, and magnetic wavefields can be useful for characterizing porous layers at two different levels of investigation: near the receivers and at greater depth.

PEMANFAATAN RADIASI ENERGI TEGANGAN 150 KV UNTUK LAMPU LED PENERANGAN JALAN

Jurnal Teknik ◽  
2018 ◽  
Vol 7 (1) ◽  
Author(s):  
Mauludi Manfaluthy
Keyword(s):  
Magnetic Field ◽  
Electric Field ◽  
High Voltage ◽  
Low Frequency ◽  
Energy Utilization ◽  
World Health ◽  
Electromagnetic Signals ◽  
Health Organization ◽  
The Magnetic Field ◽  
Low Frequency Waves

WHO (World Health Organization) concludes that not much effect is caused by electric field up to 20 kV / m in humans. WHO standard also mentions that humans will not be affected by the magnetic field under  100 micro tesla and that the electric field will affect the human body with a maximum standard of 5,000 volts per meter. In this study did not discuss about the effect of high voltage radiation SUTT (High Voltage Air Channel) with human health. The research will focus on energy utilization of SUTT radiation. The combination of electric field and magnetic field on SUTT (70-150KV) can generate electromagnetic (EM) and radiation waves, which are expected to be converted to turn on street lights around the location of high voltage areas or into other forms. The design of this prototype works like an antenna in general that captures electromagnetic signals and converts them into AC waves. With a capacitor that can store the potential energy of AC and Schottky diode waves created specifically for low frequency waves, make the current into one direction (DC). From the research results obtained the current generated from the radiation is very small even though the voltage is big enough.Keywords : Radiance Energy, Joule Thief, and  LED Module.

Investigating flexible textile-based coils for wireless charging wearable electronics

2019 ◽  
Vol 50 (3) ◽  
pp. 333-345 ◽  
Author(s):  
Danmei Sun ◽  
Meixuan Chen ◽  
Symon Podilchak ◽  
Apostolos Georgiadis ◽  
Qassim S Abdullahi ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Electrical Conductivity ◽  
Electromagnetic Field ◽  
Electric Field ◽  
Dimensional Stability ◽  
Screen Printing ◽  
Wearable Electronics ◽  
Wireless Charging ◽  
The Magnetic Field ◽  
Screen Printed

Smart and interactive textiles have been attracted great attention in recent years. This research explored three different techniques and processes in developing textile-based conductive coils that are able to embed in a garment layer. Coils made through embroidery and screen printing have good dimensional stability, although the resistance of screen printed coil is too high due to the low conductivity of the print ink. Laser cut coil provided the best electrical conductivity; however, the disadvantage of this method is that it is very difficult to keep the completed coil to the predetermined shape and dimension. The tested results show that an electromagnetic field has been generated between the textile-based conductive coil and an external coil that is directly powered by electricity. The magnetic field and electric field worked simultaneously to complete the wireless charging process.

Gas-ionizing shocks in a magnetic field

1967 ◽  
Vol 1 (1) ◽  
pp. 37-54 ◽  
Author(s):  
M. D. Cowley
Keyword(s):  
Magnetic Field ◽  
Electric Field ◽  
Wave Speed ◽  
Normal Velocity ◽  
Electrically Conducting ◽  
Shock Stability ◽  
The Face ◽  
Arbitrary Velocity ◽  
Flow Plane ◽  
The Magnetic Field

Ionizing shocks for plane flows with the magnetic field lying in the flow plane are considered. The gas is assumed to be electrically conducting downstream, but non-conducting upstream. Shocks whose downstream state has a normal velocity component less than the slow magneto-acoustic-wave speed and whose upstream state is supersonic are found to be non-evolutionary in the face of plane magneto-acoustic disturbances, unless the upstream electric field in a frame of reference where the gas is at rest is arbitrary. Velocity conditions are also determined for shock stability with the electric field not arbitrary.Shock structures are found for the case of large ohmic diffusion, the initial temperature rise and ionization of the gas being caused by a thin transition having the properties of an ordinary gasdynamic shock. For the case where shocks are evolutionary when the upstream electric field is arbitrary, the shock structure requirements only restrict the electric field by limiting the range of possible values. When shocks are evolutionary with the electric field not arbitrary, they can only have a structure for a particular value of the electric field. Limits to the current carried by ionizing shocks and the effects of precursor ionization are discussed qualitatively.

scholarly journals Mapping of steady-state electric fields and convective drifts in geomagnetic fields – Part 1: Elementary models

2016 ◽  
Vol 34 (1) ◽  
pp. 55-65 ◽  
Author(s):  
A. D. M. Walker ◽  
G. J. Sofko
Keyword(s):  
Magnetic Field ◽  
Steady State ◽  
Electric Field ◽  
Electric Fields ◽  
Magnetic Field Line ◽  
Geomagnetic Field ◽  
Geomagnetic Field Models ◽  
Spatial Derivatives ◽  
Field Lines ◽  
The Magnetic Field

Abstract. When studying magnetospheric convection, it is often necessary to map the steady-state electric field, measured at some point on a magnetic field line, to a magnetically conjugate point in the other hemisphere, or the equatorial plane, or at the position of a satellite. Such mapping is relatively easy in a dipole field although the appropriate formulae are not easily accessible. They are derived and reviewed here with some examples. It is not possible to derive such formulae in more realistic geomagnetic field models. A new method is described in this paper for accurate mapping of electric fields along field lines, which can be used for any field model in which the magnetic field and its spatial derivatives can be computed. From the spatial derivatives of the magnetic field three first order differential equations are derived for the components of the normalized element of separation of two closely spaced field lines. These can be integrated along with the magnetic field tracing equations and Faraday's law used to obtain the electric field as a function of distance measured along the magnetic field line. The method is tested in a simple model consisting of a dipole field plus a magnetotail model. The method is shown to be accurate, convenient, and suitable for use with more realistic geomagnetic field models.

scholarly journals Non-magnetic generating electricity

2021 ◽  
Author(s):  
Shuai Yang
Keyword(s):  
Magnetic Field ◽  
Magnetic Flux ◽  
Electric Field ◽  
Induced Current ◽  
Current Generation ◽  
Scientific Cognition ◽  
The Past ◽  
Directional Movement ◽  
Voltage Generation ◽  
The Magnetic Field

Abstract In the past scientific cognition, changes in the magnetic field produce electric field, so when there is current and voltage generation, need to have a change in magnetic flux, However, in the process of studying the nature of magnetization, we found that the microscopic formation of a magnetic field is the directional movement of positive and negative charges, under the guidance of this theory, we use other methods, realize the separation of positive and negative charges, observation of induced current generation, this can be used as another way to generate electricity.

Fast magnetic field penetration into low resistivity plasma

2017 ◽  
Vol 83 (1) ◽  
Author(s):  
Amnon Fruchtman
Keyword(s):  
Magnetic Field ◽  
Energy Dissipation ◽  
Electric Field ◽  
Density Gradient ◽  
Magnetic Energy ◽  
Measured Velocity ◽  
Magnetic Field Penetration ◽  
The Magnetic Field ◽  
Uniform Plasma ◽  
Field Penetration

Penetration of a magnetic field into plasma that is faster than resistive diffusion can be induced by the Hall electric field in a non-uniform plasma. This mechanism explained successfully the measured velocity of the magnetic field penetration into pulsed plasmas. Major related issues have not yet been resolved. Such is the theoretically predicted, but so far not verified experimentally, high magnetic energy dissipation, as well as the correlation between the directions of the density gradient and of the field penetration.

scholarly journals Very High-Energy Emission from the Direct Vicinity of Rapidly Rotating Black Holes

Galaxies ◽  
2018 ◽  
Vol 6 (4) ◽  
pp. 122 ◽  
Author(s):  
Kouichi Hirotani
Keyword(s):  
Magnetic Field ◽  
Black Holes ◽  
Black Hole ◽  
Electric Field ◽  
Gamma Rays ◽  
Accretion Rate ◽  
High Energy ◽  
Relativistic Electrons ◽  
Field Lines ◽  
The Magnetic Field

When a black hole accretes plasmas at very low accretion rate, an advection-dominated accretion flow (ADAF) is formed. In an ADAF, relativistic electrons emit soft gamma-rays via Bremsstrahlung. Some MeV photons collide with each other to materialize as electron-positron pairs in the magnetosphere. Such pairs efficiently screen the electric field along the magnetic field lines, when the accretion rate is typically greater than 0.03–0.3% of the Eddington rate. However, when the accretion rate becomes smaller than this value, the number density of the created pairs becomes less than the rotationally induced Goldreich–Julian density. In such a charge-starved magnetosphere, an electric field arises along the magnetic field lines to accelerate charged leptons into ultra-relativistic energies, leading to an efficient TeV emission via an inverse-Compton (IC) process, spending a portion of the extracted hole’s rotational energy. In this review, we summarize the stationary lepton accelerator models in black hole magnetospheres. We apply the model to super-massive black holes and demonstrate that nearby low-luminosity active galactic nuclei are capable of emitting detectable gamma-rays between 0.1 and 30 TeV with the Cherenkov Telescope Array.

Ein Level-Crossing-Experiment im angeregten (5p1/2 5d5/2)J=2-Term des Sn I zur Untersuchung der Energieverschiebungen im elektrischen Feld / Level-Crossing Experiment in the Excited (5p1/25d5/2)J=2-State of the Sn I for the Investigation of the Energy Shifts in an Electric Field

1970 ◽  
Vol 25 (5) ◽  
pp. 608-611
Author(s):  
P. Zimmermann
Keyword(s):  
Magnetic Field ◽  
Electric Field ◽  
Stark Effect ◽  
Second Order ◽  
Wave Functions ◽  
Zero Field ◽  
Homogeneous Electric Field ◽  
Level Crossing ◽  
Crossing Experiment ◽  
The Magnetic Field

Observing the change of the Hanle effect under the influence of a homogeneous electric field E the Stark effect of the (5p1/25d5/2)j=2-state in Sn I was studied. Due to the tensorial part β Jz2E2 in the Hamiltonian of the second order Stark effect the signal of the zero field crossing (M ∓ 2, M′ = 0 β ≷ 0 ) is shifted to the magnetic field H with gJμBH=2 | β | E2. From these shifts for different electric field strengths the value of the Stark parameter|β| = 0.21(2) MHz/(kV/cm)2 · gJ/1.13was deduced. A theoretical value of ß using Coulomb wave functions is discussed.

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