Downhole magnetometric resistivity response of a half‐plane conductor

Geophysics ◽  
1987 ◽  
Vol 52 (3) ◽  
pp. 353-362 ◽  
Author(s):  
D. M. Pai ◽  
J. P. Yeoh
Keyword(s):  
Magnetic Field ◽  
Half Plane ◽  
Current Flow ◽  
Galvanic Current ◽  
Current Electrode ◽  
Type Curves ◽  
Magnetic Field Sensors ◽  
Whole Space ◽  
Deep Underground ◽  
The Magnetic Field

The magnetometric resistivity (MMR) methods measure the magnetic field of the galvanic current flow introduced by current electrodes in the ground. The downhole MMR version overcomes some of the limitations imposed by a conductive overburden on the surface MMR methods. This paper is concerned with downhole MMR responses of buried conductors. The model considered is an infinitely conductive half‐plane conductor in a uniform whole‐space host, as an ideal representation of a plate‐like conductive orebody buried deep underground. Exact analytical downhole MMR responses are derived for arbitrary locations of current electrode sources and magnetic field sensors. Type curves are shown for various source‐sensor‐target orientations to illustrate some characteristics of the responses.

Study of MFM Application in Semiconductor Failure Analysis

2004 ◽  
Author(s):  
Way-Jam Chen ◽  
Lily Shiau ◽  
Ming-Ching Huang ◽  
Chia-Hsing Chao
Keyword(s):  
Magnetic Field ◽  
Failure Analysis ◽  
Magnetic Force Microscopy ◽  
Magnetic Force ◽  
Current Flow ◽  
Force Microscopy ◽  
The Magnetic Field ◽  
A Current

Abstract In this study we have investigated the magnetic field associated with a current flowing in a circuit using Magnetic Force Microscopy (MFM). The technique is able to identify the magnetic field associated with a current flow and has potential for failure analysis.

scholarly journals The Detector Control System for the magnetic field sensors in New Small Wheel phase I upgrade of ATLAS detector

2021 ◽  
Vol 2105 (1) ◽  
pp. 012026
Author(s):  
Stamatios Tzanos
Keyword(s):  
Magnetic Field ◽  
Control System ◽  
Hadron Collider ◽  
Atlas Detector ◽  
Magnetic Field Sensors ◽  
Atlas Experiment ◽  
Data Rates ◽  
Level 1 ◽  
The Magnetic Field ◽  
Detector Control System

Abstract In conjunction with the High Luminosity upgrade of the Large Hadron Collider accelerator at CERN, the ATLAS detector is also undergoing an upgrade to handle the significantly higher data rates. The muon end-cap system upgrade in ATLAS, lies with the replacement of the Small Wheel. The New Small Wheel (NSW) is expected to combine high tracking precision with upgraded information for the Level-1 trigger. To accomplish this, small Thin Gap Chamber (sTGC) and MicroMegas detector technologies are being deployed. Due to their installation location in ATLAS, the effects of Barrel Toroid and End-Cap Toroid magnets on NSW must be measured. For the final experiment at ATLAS, each sTGC large double wedge will be equipped with magnetic field Hall effect sensors to monitor the magnetic field near the NSW. The readout is done with an Embedded Local Monitor Board (ELMB) called MDT DCS Module (MDM). For the integration of this hardware in the experiment, first, a detector control system was developed to test the functionality of all sensors before their installation on the detectors. Subsequently, another detector control system was developed for the commissioning of the sensors. Finally, a detector control system based on the above two is under development for the expert panels of ATLAS experiment. In this paper, the sensor readout, the connectivity mapping and the detector control systems will be presented.

On the theory of magnetometric resistivity (MMR) methods

Geophysics ◽  
1978 ◽  
Vol 43 (6) ◽  
pp. 1176-1203 ◽  
Author(s):  
R. N. Edwards ◽  
H. Lee ◽  
M. N. Nabighian
Keyword(s):  
Theoretical Basis ◽  
Field Data ◽  
Current Flow ◽  
Low Frequency ◽  
Finite Conductivity ◽  
Type Curves ◽  
Two Factors ◽  
The Magnetic Field ◽  
Theoretical Results ◽  
Conductivity Contrast

The Magnetometric Resistivity (MMR) method is based on the measurement of the low‐level, low‐frequency magnetic fields associated with noninductive current flow in the ground. A component of the magnetic field is measured in the vicinity of one or more grounded electrodes. Recently, the method was tested successfully in the field. The present paper presents the theoretical basis of the method in a unified format. Part of the material is derived from valuable published papers which are difficult to obtain. The remainder of the paper contains original unpublished theoretical results. It is shown that a horizontally layered earth yields no MMR anomaly. The characteristic anomalies for an anisotropic earth, vertical and dipping contacts, thin and thick dikes, and semicylindrical and hemispherical depressions, as well as alpha media are presented in detail. There are two factors which influence the MMR anomaly; geometry and conductivity contrast. For many models, it is possible to separate these two effects. Type curves are presented for very large conductivity contrasts to illustrate the effect of geometry only. Ancillary curves enable finite conductivity contrasts to be deduced from field data.

Magnetoresistive Switch Effect and Its Application to Magnetic Field Sensors

2005 ◽  
Vol 475-479 ◽  
pp. 2223-2226
Author(s):  
Zhi-gang Sun ◽  
Masaki Mizuguchi ◽  
Hiroyuki Akinaga
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Threshold Voltage ◽  
Wet Etching ◽  
Magnetic Field Sensors ◽  
Field Sensitivity ◽  
Gaas Substrates ◽  
Etching Method ◽  
Magnetic Filed ◽  
The Magnetic Field

Magnetoresistive switch effect (MRS effect) devices containing two gold (Au) electrodes with a gap less than 2 µm were successfully fabricated on semi-insulting GaAs substrates by wet etching method. Huge MRS effect was observed. Magnetoresistance (MR) ratio reached 1,000,000% under the magnetic filed of 1.5 T when the devices were operated just above the threshold voltage. The magnetic field sensitivity at small magnetic fields was significantly improved. MR ratio of more than 1000% was achieved at 0.03 T. A relative high MR ratio of 100,000% under the magnetic filed of 1.5 T was also achieved when the devices operating before the threshold voltage.

The Magnetoelastic Problem for a Soft Ferromatnetic Elastic Half-Plane with a Crack and a Constant Magneic Induction

2009 ◽  
Vol 25 (1) ◽  
pp. 95-102 ◽  
Author(s):  
C.-S. Yeh ◽  
C.-W. Ren
Keyword(s):  
Magnetic Field ◽  
Stress Intensity Factor ◽  
Free Surface ◽  
Stress Intensity ◽  
Stress State ◽  
Intensity Factor ◽  
Half Plane ◽  
Elastic Solid ◽  
Soft Ferromagnetic ◽  
The Magnetic Field

AbstractThe stress state of a magnetized elastic half-plane with a uniformly pressurized crack parallel to the free surface subjected to a uniform magnetic induction Bo is considered. The linear theory for a soft ferromagnetic elastic solid with muti-domain structure, which has been developed by Pao and Yeh [1] is adopted to investigate this problem. A numerical method is developed to determine the magnetoelastic stress intensity factor. The effect of the magnetic field and the boundary conditions on the magnetoelasitc stress intensity factor are shown graphically and numerically.

New Developments to Reduce Arc Blow during SMAW of Pipelines

2018 ◽  
Vol 938 ◽  
pp. 96-103 ◽  
Author(s):  
Sergey V. Baklanov ◽  
Anton S. Gordynets ◽  
A.S. Kiselev ◽  
Mikhail S. Slobodyan
Keyword(s):  
Magnetic Field ◽  
Direct Current ◽  
Arc Welding ◽  
Alternating Current ◽  
Shielded Metal Arc Welding ◽  
Electrode Coating ◽  
Current Electrode ◽  
Repair Work ◽  
Metal Arc Welding ◽  
The Magnetic Field

In some cases, magnetic blow does not allow using direct current for shielded metal arc welding. This is especially true for repair work on pipelines after magnetic flaw detection. Alternating current is useful to control magnetic arc blow during welding. The most promising results give technologies using alternating current with a rectangular waveform. However, the advantages of this method have not been used until now. The main goal of this study is to determine the influence of the parameters of the arc on its stability and the metal transfer mode during shielded metal arc welding under perturbing action of the magnetic field. The proposed methodology of experimental research allowed identifying the cause of arc extinction using direct current electrode positive. This is due to displacement of molten droplets of metal by the magnetic field from of the uneven melted electrode coating and its subsequent separation. This problem was solved using alternating current with the square waveform pulse mode at a frequency of 500 Hz. The amplitude-time parameters of the current pulses provide stabilization of the arc and volume of the molten electrode metal.

Magnetometric resistivity (MMR) anomalies of two‐dimensional structures

Geophysics ◽  
1979 ◽  
Vol 44 (5) ◽  
pp. 947-958 ◽  
Author(s):  
E. Gomez Trevino ◽  
R. N. Edwards
Keyword(s):  
Magnetic Field ◽  
Integral Equation ◽  
Fourier Transform ◽  
Electric Field ◽  
Current Source ◽  
Two Dimensional ◽  
Galvanic Current ◽  
One Dimensional ◽  
The Magnetic Field ◽  
Surface Integrals

An inexpensive, rapid method has been developed for computing all three components of the magnetic field due to galvanic current flow from a point electrode in the vicinity of a conductive subsurface structure of infinite strike‐length and arbitrary cross‐section. For any three‐dimensional (3-D) structure, the magnetic field may be written as a sum of surface integrals over boundaries defining changes in conductivity by a direct modification of the Biot‐Savart law. The integrand of each surface integral includes the components of the electric field tangential to the boundary, which may be evaluated on the boundary using a standard integral equation technique. In the case of a two‐dimensional (2-D) structure, a reformulation of the theory by taking a one‐dimensional Fourier transform along the strike results in the reduction of both the surface integrals necessary to solve the integral equation for the electric field, and the integrals used in computing the magnetic field, to line integrals in wavenumber domain. We evaluate the integrals numerically and solve the integral equation for each of about ten wavenumbers; finally, we obtain the magnetic field in space domain through a concluding one‐dimensional inverse Fourier transform. Type curves and characteristic curves for the simple model of a buried horizontal cylinder beneath a thin layer of conductive overburden are constructed. In the absence of overburden, the half‐width of the anomaly is linearly related to the depth of the cylinder. In the presence of overburden, the form of the anomaly may be predicted in a simple manner from the corresponding anomaly in the absence of overburden, provided the distance from the current source is sufficiently large for most of the available current to have penetrated the overburden.

Measurements of RF-Induced SOL Modifications in Tore Supra Tokamak

2012 ◽  
Author(s):  
Martin Kubič ◽  
James P. Gunn ◽  
Laurent Colas ◽  
Stéphane Heuraux ◽  
Eric Faudot
Keyword(s):  
Magnetic Field ◽  
Radio Frequency ◽  
Flow Pattern ◽  
Current Flow ◽  
Power Ratio ◽  
Electrical Field ◽  
Ion Cyclotron ◽  
New Type ◽  
Field Lines ◽  
The Magnetic Field

Since spring 2011, one of the three ion cyclotron reconance heating (ICRH) antennas in the Tore Supra (TS) tokamak is equipped with a new type of Faraday screen (FS). Results from Radio Frequency (RF) simulations of the new Faraday screen suggest the innovative structure with cantilevered bars and ‘shark tooth’ openings significantly changes the current flow pattern on the front of the antenna which in turn reduces the RF potential and RF electrical field in particular parallel to the magnetic field lines which contributes to generating RF sheaths. Effects of the new FS operation on RF-induced scrape-off layer (SOL) modifications are studied for different plasma and antenna configurations — scans of strap power ratio imbalance, phasing, injected power and SOL density.

Effect of conductive host rock on borehole transient electromagnetic responses

Geophysics ◽  
1989 ◽  
Vol 54 (5) ◽  
pp. 598-608 ◽  
Author(s):  
Gregory A. Newman ◽  
Walter L. Anderson ◽  
Gerald W. Hohmann
Keyword(s):  
Magnetic Field ◽  
Half Space ◽  
Time Derivative ◽  
The Body ◽  
Galvanic Current ◽  
Large Loop ◽  
Transient Electromagnetic ◽  
Electromagnetic Responses ◽  
Pass Through ◽  
The Magnetic Field

Transient electromagnetic (TEM) borehole responses of 3-D vertical and horizontal tabular bodies in a half‐space are calculated to assess the effect of a conductive host. The transmitter is a large loop at the surface of the earth, and the receiver measures the time derivative of the vertical magnetic field. When the host is conductive (100 Ω ⋅ m), the borehole response is due mainly to current channeled through the body. The observed magnetic‐field response can be visualized as due to galvanic currents that pass through the conductor and return in the half‐space. When the host resistivity is increased, the magnetic field of the conductor is influenced more by vortex currents that flow in closed loops inside the conductor. For a moderately resistive host (1000 Ω ⋅ m), the magnetic field of the body is caused by both vortex and galvanic currents. The galvanic response is observed at early times, followed by the vortex response at later times if the body is well coupled to the transmitter. If the host is very resistive, the galvanic response vanishes; and the response of the conductor is caused only by vortex currents. The shapes of the borehole profiles change considerably with changes in the host resistivity because vortex and galvanic current distributions are very different. When only the vortex response is observed, it is easy to distinguish vertical and horizontal conductors. However, in a conductive host where the galvanic response is dominant, it is difficult to interpret the geometry of the body; only the approximate location of the body can be determined easily. For a horizontal conductor and a single transmitting loop, only the galvanic response enables one to determine whether the conductor is between the transmitter and the borehole or beyond the borehole. A field example shows behavior similar to that of our theoretical results.

Extraordinary magnetoresistance: sensing the future

Open Physics ◽  
2012 ◽  
Vol 10 (3) ◽  
Author(s):  
Thomas Hewett ◽  
Feodor Kusmartsev
Keyword(s):  
Magnetic Field ◽  
Contact Resistance ◽  
High Mobility ◽  
Future Application ◽  
The Finite Element Method ◽  
Metal Interface ◽  
Magnetic Field Sensors ◽  
Extraordinary Magnetoresistance ◽  
Best Fit ◽  
The Magnetic Field

AbstractSimulations utilising the finite element method (FEM) have been produced in order to investigate aspects of circular extraordinary magnetoresistance (EMR) devices. The effect of three specific features on the resultant magnetoresistance were investigated: the ratio of the metallic to semiconducting conductivities (σ M/σ S); the semiconductor mobility; and the introduction of an intermediate region at the semiconductormetal interface in order to simulate a contact resistance. In order to obtain a large EMR effect the conductivity ratio (σ M/σ S) is required to be larger than two orders of magnitude; below this critical value the resultant magnetoresistance effect is dramatically reduced. Large mobility semiconductors exhibit larger EMR values for a given field (below saturation) and reduce the magnetic field required to produce saturation of the magnetoresistance. This is due to a larger Hall angle produced at a given magnetic field and is consistent with the mechanism of the EMR effect. Since practical magnetic field sensors are required to operate at low magnetic fields, high mobility semiconductors are required in the production of more sensitive EMR sensors. The formation of a Schottky barrier at the semiconductor-metal interface has been modelled with the introduction of a contact resistance at the semiconductor-metal interface. Increasing values of contact resistance are found to reduce the EMR effect with it disappearing altogether for large values. This has been shown explicitly by looking at the current flow in the system and is consistent with the mechanism of the EMR effect. The interface resistance was used to fit the simulated model to existing experimental data. The best fit occurred with an interface with resistivity of 1.55×10−4 m (overestimate). The EMR effect holds great potential with regard to its future application to magnetic field sensors. The design of any such devices should incorporate high mobility materials (such as graphene) along with the specific features presented in this paper in order to produce effective magnetic field sensors.

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