A borehole induction procedure for investigating electrical conductivity structure within the broad vicinity of a hole

Geophysics ◽  
1981 ◽  
Vol 46 (1) ◽  
pp. 65-67 ◽  
Author(s):  
M. H. Worthington ◽  
A. Kuckes ◽  
M. Oristaglio
Keyword(s):  
Magnetic Field ◽  
Electrical Conductivity ◽  
Small Diameter ◽  
Effective Cross Section ◽  
Induction Procedure ◽  
Diameter Hole ◽  
Conductivity Structure ◽  
Metal Frame ◽  
The Magnetic Field ◽  
Broad Region

A field test was carried out of a controlled‐source induction procedure in which a source loop was positioned on the surface of the ground encircling a borehole, and the horizontal component of the magnetic field was measured within the hole. The problem of measuring the component of an alternating magnetic field at right angles to a small diameter hole was overcome by the construction of a μ‐metal frame for the induction coil that greatly increased the effective cross‐section of the coil. Data obtained with this configuration of source and receiver are dependent upon the electrical conductivity of the ground within a broad region around the hole. The method is effective in providing constraints on the location and distribution of regions of anomalous electrical conductivity which are not revealed by the drilling operation. These conclusions are supported by theoretical estimates of the magnetic field that would result from known conductivity distributions obtained using finite element techniques.

Transport measurements in annealed single crystal tellurium

1970 ◽  
Vol 48 (24) ◽  
pp. 3038-3046 ◽  
Author(s):  
C. H. Champness ◽  
A. L. Kipling
Keyword(s):  
Magnetic Field ◽  
Electrical Conductivity ◽  
Single Crystal ◽  
Room Temperature ◽  
Small Diameter ◽  
Impurity Scattering ◽  
Czochralski Method ◽  
Liquid Nitrogen Temperature ◽  
Carrier Analysis ◽  
The Magnetic Field

Single crystal samples of tellurium obtained from small diameter ingots, specially grown by the Czochralski method from a melt of the purified element, were studied by measuring the electrical conductivity (σ), Hall coefficient (RH), and transverse magnetoresistance (Δρ/ρ0). As a result of annealing and etching, the Hall mobility (RHσ) and Δρ/ρ0 were substantially increased in the samples at liquid nitrogen temperature, while RH was slightly decreased. The samples were completely intrinsic above 250 °K and at room temperature Δρ/ρ0 was strictly proportional to the square of the magnetic field. Like RH and σ at this temperature, it was also independent of sample history. Two-carrier analysis at room temperature gave electron and hole mobilities of 1890 and 790 cm2 V−1 s−1 respectively. At 77 °K, Δρ/ρ0 in the annealed and etched samples was larger than expected for a simple one-carrier model with a mixture of lattice and impurity scattering.

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.

scholarly journals Hydromagnetic dynamos in rotating spherical fluid shells in dependence on the Prandtl number, density stratification and electromagnetic boundary conditions

2014 ◽  
Vol 44 (4) ◽  
pp. 293-312 ◽  
Author(s):  
Tomáš Šoltis ◽  
Ján Šimkanin
Keyword(s):  
Magnetic Field ◽  
Electrical Conductivity ◽  
Magnetic Fields ◽  
Prandtl Number ◽  
Inner Core ◽  
Polar Regions ◽  
Number Density ◽  
Magnetic Diffusion ◽  
Spherical Fluid ◽  
The Magnetic Field

Abstract We present an investigation of dynamo in a simultaneous dependence on the non-uniform stratification, electrical conductivity of the inner core and the Prandtl number. Computations are performed using the MAG dynamo code. In all the investigated cases, the generated magnetic fields are dipolar. Our results show that the dynamos, especially magnetic field structures, are independent in our investigated cases on the electrical conductivity of the inner core. This is in agreement with results obtained in previous analyses. The influence of non-uniform stratification is for our parameters weak, which is understandable because most of the shell is unstably stratified, and the stably stratified region is only a thin layer near the CMB. The teleconvection is not observed in our study. However, the influence of the Prandtl number is strong. The generated magnetic fields do not become weak in the polar regions because the magnetic field inside the tangent cylinder is always regenerated due to the weak magnetic diffusion.

The stability of viscous flow between rotating cylinders in the presence of a magnetic field

1953 ◽  
Vol 216 (1126) ◽  
pp. 293-309 ◽  
Keyword(s):  
Magnetic Field ◽  
Electrical Conductivity ◽  
Viscous Flow ◽  
Thermal Instability ◽  
Horizontal Layer ◽  
Rotational Stability ◽  
Marginal Stability ◽  
Inhibiting Effect ◽  
The Stability ◽  
The Magnetic Field

In this paper the theory of the stability of viscous flow between two rotating coaxial cylinders which has been developed by Taylor, Jeffreys and Meksyn is extended to the case when the fluid considered is an electrical conductor and a magnetic field along the axis of the cylinders is present. A differential equation of order eight is derived which governs the situation in marginal stability; and a significant set of boundary conditions for the problem is formulated. The case when the two cylinders are rotating in the same direction and the difference ( d ) in their radii is small compared to their mean (R 0 ) is investigated in detail. A variational procedure for solving the underlying characteristic value problem and determining the critical Taylor numbers for the onset of instability is described. As in the case of thermal instability of a horizontal layer of fluid heated below, the effect of the magnetic field is to inhibit the onset of instability, the inhibiting effect being the greater, the greater the strength of the field and the value of the electrical conductivity. In both cases, the inhibiting effect of the magnetic field depends on the strength of the field ( H ), the density ( ρ ) and the coefficients of electrical conductivity ( σ ), kinematic viscosity ( v ) and magnetic permeability ( μ ) through the same non-dimensional combination Q =μ 2 H 2 d 2 σ/ pv ; however, the effect on rotational stability is more pronounced than on thermal instability. A table of the critical Taylor numbers for various values of Q is provided.

scholarly journals The Electrical Conductivity of a Partially Ionized Argon-Potassium Plasma in a Magnetic Field

1966 ◽  
Vol 21 (9) ◽  
pp. 1468-1470 ◽  
Author(s):  
W. Feneberg
Keyword(s):  
Magnetic Field ◽  
Electrical Conductivity ◽  
Laguerre Polynomials ◽  
Lorentz Gas ◽  
Small Deviations ◽  
Starting Point ◽  
Potassium Plasma ◽  
Partially Ionized ◽  
Ramsauer Effect ◽  
The Magnetic Field

In the case of small deviations from thermal equilibrium the second ENSKOG approximation is used as a starting point for solving the BOLTZMANN equation of the electrons in a partially ionized plasma. The distribution function is expanded according to LAGUERRE polynomials up to the order of 3. In this order the electrical conductivity of a LORENTZ gas, which is known exactly, is obtained to an accuracy of roughly 5%. The approximation tested in this way was then used to calculate the conductivity of an argon-potassium mixture at electron temperatures between 2000°K and 3500°K.If only he collisions between electrons and argon atoms were to be considered, the electrical conductivity in the absence of a magnetic field would, in view of the RAMSAUER effect, be greater by a factor of 2.8 than that obtained with an infinitely strong magnetic field. When the interaction with the potassium atoms and the COULOMB interaction are taken into account as well the conductivity in the magnetic field varies by about 20%.

scholarly journals Using the Carotazh Method to Determine the Electrical Characteristics of the Earth’s Subsoil

2021 ◽  
Keyword(s):  
Magnetic Field ◽  
Electrical Conductivity ◽  
Electromagnetic Field ◽  
Surface Impedance ◽  
Electromagnetic Waves ◽  
Dielectric Permeability ◽  
Electrical Characteristics ◽  
Measuring Systems ◽  
The Earth ◽  
The Magnetic Field

Logging is a detailed study of the structure of the well incision by descent and ascent of a geophysical probe. It is often used to determine the electrical conductivity of terrestrial depths. To do this, the sides of the well deepen the electrodes, and they are fed into the depths of a constant electric current. However, if you use natural or artificial electromagnetic waves, it becomes possible to determine the dielectric permeability of terrestrial rocks at depth. To do this, the surface impedance is first measured on the surface of the earth, and then by measuring at a certain frequency of the electromagnetic field in the well hole, the electrical conductivity and dielectric permeability of terrestrial rocks are calculated by fairly simple formulas. Such measurements can be carried out by standard measuring systems, adding only a narrow frame with wire winding to measure the magnetic field.

Geophysical mapping during the planning of new roads: an aid to the detection of mine-workings

1987 ◽  
Vol 4 (1) ◽  
pp. 447-452 ◽  
Author(s):  
P. D. Jackson ◽  
D. M. McCann ◽  
D. L. Russell
Keyword(s):  
Magnetic Field ◽  
Electrical Conductivity ◽  
Magnetic Anomalies ◽  
Surrounding Rock ◽  
Drainage Pattern ◽  
Conductivity Anomaly ◽  
Area North ◽  
Geophysical Anomalies ◽  
The Magnetic Field ◽  
Geophysical Mapping

AbstractMagnetic field strength and electrical conductivity surveys have been made over an extensively mined area north of Dalton-in-Furness along parts of a proposed by-pass route. This approach was successful in detecting shafts and other workings, which were brick-lined and back-filled with debris and ash, since the magnetic field and electrical conductivity values are normally higher in the vicinity of such areas. The use of non-contacting instruments resulted in the rapid location of the geophysical anomalies associated with the contrast in the physical properties between the material in-filling the mine shafts and the surrounding rock mass. Shafts covered with debris or back-filled with the original overburden did not generally give rise to significant magnetic anomalies but often produced a conductivity anomaly associated with changes in the drainage pattern of the area resulting from the presence of the shaft.

THE BIANCHI TYPE V MAGNETIZED STRING DUST COSMOLOGICAL MODEL IN GENERAL RELATIVITY

2007 ◽  
Vol 16 (11) ◽  
pp. 1769-1781 ◽  
Author(s):  
RAJ BALI ◽  
SHILPI JAIN
Keyword(s):  
Magnetic Field ◽  
Electrical Conductivity ◽  
General Relativity ◽  
Cosmological Model ◽  
Bianchi Type ◽  
Fluid Distribution ◽  
Type V ◽  
The Magnetic Field ◽  
Bianchi Type V ◽  
Nonvanishing Component

The Bianchi type V magnetized string dust cosmological model for perfect fluid distribution is investigated. We assume that the magnetic field is along the x direction, so F23 is the only nonvanishing component of Fij. We also find that F14 = 0 = F24 = F34 due to the assumption of infinite electrical conductivity. The behavior of the model in the presence and the absence of a magnetic field is also discussed.

scholarly journals Reflection and dissipation of oblique Alfvén waves in an isothermal atmosphere

1999 ◽  
Vol 22 (1) ◽  
pp. 161-169 ◽  
Author(s):  
Hadi Yahya Alkahby ◽  
M. A. Mahrous
Keyword(s):  
Magnetic Field ◽  
Electrical Conductivity ◽  
Transition Region ◽  
Solar Atmosphere ◽  
Alfven Waves ◽  
Alfvén Waves ◽  
Heating Mechanism ◽  
Downward Propagation ◽  
Isothermal Atmosphere ◽  
The Magnetic Field

In this article, we investigate the combined effects of viscosity and Ohmic electrical conductivity on upward and downward propagation oblique Alfvén waves in an isothermal atmosphere. It is shown that the presence and direction of the magnetic field play an important role in the structure and the heating mechanism of solar atmosphere. In addition, the atmosphere can be divided into two distinct regions connected by a transition region. In the lower region, the solution can be written as a linear combination of an upward and a downward propagation wave with unequal wavelengths. In the upper region, the solution decays exponentially with the altitude. Moreover, the magnetic field creates a reflecting and a non-absorbing transition region. On the contrary, the viscosity and Ohmic electrical conductivity produce a reflecting and an absorbing transition region. The nature of the transition region depends on the relative strength of the viscous diffusivity with respect to the resistive diffusivity and on the direction of the magnetic field. A unique solution is determined. The reflection coefficient and damping factors are derived and the conclusions are discussed in connection with the nature of the heating mechanism of the solar atmosphere.

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