scholarly journals Modeling magnetostratigraphy in a borehole

Geophysics ◽  
1989 ◽  
Vol 54 (8) ◽  
pp. 973-983 ◽  
Author(s):  
Yves Gallet ◽  
Vincent Courtillot
Keyword(s):  
Magnetic Field ◽  
Remanent Magnetization ◽  
Operation Mode ◽  
Resolving Power ◽  
Vertical Profiles ◽  
Rock Property ◽  
Hole Radius ◽  
Differential Operation ◽  
Vector Magnetometer ◽  
The Magnetic Field

The magnetic field along a hole bored through a sequence of dipping layers with varying magnetization and planar interfaces is calculated. The emphasis is on recovering remanent magnetization polarity transitions for magnetostratigraphic applications (dating, correlations), although intensity of remanent magnetization can in itself be a useful rock property. Results are presented for various cases of geologic interest in the form of axial vertical profiles and section maps of the holes at varying distances from polarity reversal interfaces. The vertical profiles demonstrate a resolving power of about six times the hole radius; meaningful magnetostratigraphies can be expected for rocks with a magnetization larger than [Formula: see text], for instruments with a sensitivity of 0.1 nT. In a number of natural occurrences, it may not be necessary to resort to progressive demagnetization to recover the polarity sequence. Depending on which magnetic field and magnetization component one looks at, the section maps display characteristic patterns, in which, for instance, the direction of magnetization and the dip of the layers interfere. These maps are discussed in some detail. They can be used as guidelines to build a multisensor vector magnetometer (downhole magnetostratigraphic tool), whose output should be coupled with measurement of magnetic susceptibility for reduction of induced magnetization and with output from a surface instrument in a differential operation mode to reduce transient magnetic variations.

A Super-High-Resolution HVEM (H-1500) Newly Installed in NIRIM

1990 ◽  
Vol 48 (1) ◽  
pp. 142-143
Author(s):  
S. Horiuchi ◽  
Y. Matsui
Keyword(s):  
Magnetic Field ◽  
High Resolution ◽  
Chromatic Aberration ◽  
Inorganic Materials ◽  
Electron Gun ◽  
Resolving Power ◽  
National Budget ◽  
Voltage Electron ◽  
Specimen Holder ◽  
The Magnetic Field

A new high-voltage electron microscope (H-1500) specially aiming at super-high-resolution (1.0 Å point-to-point resolution) is now installed in National Institute for Research in Inorganic Materials ( NIRIM ), in collaboration with Hitachi Ltd. The national budget of about 1 billion yen including that for a new building has been spent for the construction in the last two years (1988-1989). Here we introduce some essential characteristics of the microscope.(1) According to the analysis on the magnetic field in an electron lens, based on the finite-element-method, the spherical as well as chromatic aberration coefficients ( Cs and Cc ). which enables us to reach the resolving power of 1.0Å. have been estimated as a function of the accelerating As a result of the calculaton. it was noted that more than 1250 kV is needed even when we apply the highest level of the technology and materials available at present. On the other hand, we must consider the protection against the leakage of X-ray. We have then decided to set the conventional accelerating voltage at 1300 kV. However. the maximum accessible voltage is 1500 kV, which is practically important to realize higher voltage stabillity. At 1300 kV it is expected that Cs= 1.7 mm and Cc=3.4 mm with the attachment of the specimen holder, which tilts bi-axially in an angle of 35° ( Fig.1 ). In order to minimize the value of Cc a small tank is additionally placed inside the generator tank, which must serve to seal the magnetic field around the acceleration tube. An electron gun with LaB6 tip is used.

Quasi-static magnetic field changes associated with the CANNIKIN nuclear explosion

1972 ◽  
Vol 62 (6) ◽  
pp. 1479-1487 ◽  
Author(s):  
W. P. Hasbrouck ◽  
J. H. Allen
Keyword(s):  
Magnetic Field ◽  
Residual Stresses ◽  
Static Magnetic Field ◽  
Remanent Magnetization ◽  
Nuclear Explosion ◽  
Average Increase ◽  
Ground Zero ◽  
Total Magnetic Field ◽  
Fault Trace ◽  
The Magnetic Field

abstract As a result of the CANNIKIN nuclear explosion, the magnetic field several kilometers from the epicenter appears to have been permanently altered. Within 30 sec after detonation, a proton magnetometer 3 km away recorded a 9-gamma step increase in total magnetic field. Continuous difference recordings between the station at a distance of 3 km from the epicenter and one at 9 km showed that a 7.0-gamma average increase was maintained between these locations for 8 days after the shot. Along a 12-km traverse centered across a portion of a fault 1.6 km from ground zero, postshot-minus-preshot magnetic field difference readings decreased semi-sinusoidally from a high value of +13 gammas in the shot-contained block to a low value of −11 gammas in the distal block. Within 15 m to either side of the fault trace, a 15-gamma wedge-shaped magnetic low was observed. The magnetic effects can be reasonably interpreted as being caused by either shot-produced residual stresses or shot-caused alterations of remanent magnetization.

Noise Equivalent Power of Graphene–Superconductor-Based Optical Sensor

2017 ◽  
Vol 16 (01) ◽  
pp. 1750006
Author(s):  
B. Afkhami Aghda ◽  
A. Moftakharzadeh ◽  
M. Hosseini
Keyword(s):  
Magnetic Field ◽  
Optical Sensors ◽  
Operation Mode ◽  
Noise Equivalent Power ◽  
Direct Relation ◽  
Phonon Interaction ◽  
Electron Phonon Interaction ◽  
Device Resistance ◽  
Conductivity Electron ◽  
The Magnetic Field

In this paper, the noise equivalent power (NEP) of optical sensors based on graphene–superconductor junctions in the voltage bias operation mode has been calculated. The effects of device parameters such as temperature, magnetic field and device resistance on the NEP of these detectors have been thoroughly investigated. By solving the related equations, graphene specific heat, thermal conductivity, electron–phonon interaction and responsivity of the detector have been obtained. Using the calculated parameters, the NEP of the device was obtained. The results show that at constant magnetic field the NEP will increase linearly by increasing device temperature. On the other hand, at constant temperature the behavior of NEP versus magnetic field is first increasing and then decreasing. Our calculations show that the optimal resistance of the device has a direct relation with respect to the device temperature, while in the investigated operating range the optimal resistance of device is almost independent of the magnetic field.

MAGNETO-OPTICS OF QUANTUM DOTS IN THE NEAR FIELD

2007 ◽  
Vol 21 (08n09) ◽  
pp. 1649-1653
Author(s):  
CONSTANTINOS SIMSERIDES ◽  
ANNA ZORA ◽  
GEORGIOS TRIBERIS
Keyword(s):  
Magnetic Field ◽  
Spatial Resolution ◽  
Near Field ◽  
Resolving Power ◽  
Zero Magnetic Field ◽  
Far Field ◽  
Field Orientation ◽  
Structural Symmetry ◽  
Near Field Optics ◽  
The Magnetic Field

We examine a quantum dot (QD) illuminated in the near field with subwavelength spatial resolution, while simultaneously it is subjected to a magnetic field of variable orientation and magnitude. The magnetic field orientation can conserve or destroy the zero-magnetic-field ("structural") symmetry. The asymmetry induced by the magnetic field -except for specific orientations along symmetry axes- can be uncovered in the near-field (NF) but not in the far-field (FF) spectra. We predict that NF magnetoabsorption experiments of realistic spatial resolution could reveal the QD symmetry. This exceptional symmetry-resolving power of the near-field optics, is lost in the far field.

Mitigating remanent magnetization effects in magnetic data using the normalized source strength

Geophysics ◽  
2013 ◽  
Vol 78 (3) ◽  
pp. J25-J32 ◽  
Author(s):  
Mark Pilkington ◽  
Majid Beiki
Keyword(s):  
Magnetic Field ◽  
Remanent Magnetization ◽  
Field Data ◽  
Magnetic Data ◽  
Magnetization Distribution ◽  
Source Strength ◽  
Inversion Algorithm ◽  
Data Set ◽  
Magnetic Field Data ◽  
The Magnetic Field

We have developed an approach for the interpretation of magnetic field data that can be used when measured anomalies are affected by significant remanent magnetization components. The method deals with remanent effects by using the normalized source strength (NSS), a quantity calculated from the eigenvectors of the magnetic gradient tensor. The NSS is minimally affected by the direction of remanent magnetization present and compares well with other transformations of the magnetic field that are used for the same purpose. It therefore offers a way of inverting magnetic data containing the effects of remanent magnetizations, particularly when these are unknown and are possibly varying within a given data set. We use a standard 3D inversion algorithm to invert NSS data from an area where varying remanence directions are apparent, resulting in a more reliable image of the subsurface magnetization distribution than possible using the observed magnetic field data directly.

scholarly journals Observation of scissors modes in solid state systems with a SQUID

2016 ◽  
Vol 23 (2) ◽  
pp. 560-565 ◽  
Author(s):  
Keisuke Hatada ◽  
Kuniko Hayakawa ◽  
Fabrizio Palumbo ◽  
Augusto Marcelli
Keyword(s):  
Magnetic Field ◽  
Quantum Interference ◽  
Resolving Power ◽  
Wide Energy Range ◽  
Resonance Fluorescence ◽  
Superconducting Quantum Interference Device ◽  
Unit Cells ◽  
Wide Energy ◽  
The Magnetic Field ◽  
Very High

The occurrence of scissors modes in crystals that have deformed ions in their unit cells was predicted some time ago. The theoretical value of their energy is rather uncertain, however, ranging between ten and a few tens of eV, with the corresponding widths of 10−7to 10−6 eV. Their observation by resonance fluorescence experiments therefore requires a photon spectrometer covering a wide energy range with a very high resolving power. Here, a new experiment is proposed and discussed in which such difficulties are overcome by measuring with a superconducting quantum interference device (SQUID) the variation of the magnetic field associated with the excitation of scissors modes.

Influence of Remanent Magnetization on Pitting Corrosion in Pipeline Steel

2010 ◽  
Author(s):  
J. H. Espina-Herna´ndez ◽  
F. Caleyo ◽  
J. M. Hallen ◽  
A. Lo´pez-Montenegro ◽  
E. Pe´rez-Baruch
Keyword(s):  
Magnetic Field ◽  
Pitting Corrosion ◽  
Remanent Magnetization ◽  
Pipeline Steel ◽  
Local Magnetic Field ◽  
Extreme Value Analysis ◽  
Pit Depth ◽  
Pipeline Wall ◽  
The Magnetic Field ◽  
Control Samples

These days, in-line inspections based on the magnetic flux leakage (MFL) principle are routinely used to detect and size metal loss and mechanical anomalies in operating oil and gas pipelines. One of the characteristics of the MFL technology is that after the inspection, the pipeline wall shows a remanent magnetization. In this work, the influence of the magnetic field on pitting corrosion in pipeline steel is studied. Pitting corrosion experiments have been carried out on samples of an API 5L grade 52 steel under a magnetization level of the same order of magnitude of the remanent magnetization in the pipeline wall after the MFL inspection. The samples were magnetized using rings of the investigated steel. The closed magnetic circuit configuration used in this study survey guaranteed that the samples kept the same magnetization level during the complete duration of the conducted experiments. This experimental setup was used in order to reproduce the conditions observed in MFL-inspected pipelines in which the magnetic field was confined to the pipe wall thickness. Immediately after magnetization, the investigated samples were subjected to pitting by immersing them in a solution with dissolved Cl− and SO42− ions. The pitting experiments were conducted for exposure times of 7 days. Non-magnetized specimens were used as control samples. The depths of the pits induced in the investigated samples were measured using optical microscopy. The maximum pit depth of each sample was recorded and used to conduct extreme value analysis of the pitting process in the magnetized and non-magnetized specimens. The results of this investigation indicate that the magnetic field confined within the pipeline wall has a significant influence on the pitting corrosion process. The statistical assessment of the pitting corrosion data collected during this study shows that the magnetic field reduces the average depth of the pit population. It also reduces the extreme pit depth values that can be predicted from the maximum values observed in the magnetized samples, with respect to the non-magnetized control samples. Scanning electron microscopy observations show that the magnetic field alters the pit morphology by increasing the pit opening (mouth). It is shown that the observed reduction in the pit depth when a magnetic field is confined to the volume of the corroding material can be explained based on the behavior of the paramagnetic corrosion products under the influence of the local magnetic field gradients produced inside and within the immediate vicinity of stable pits.

Magnetic vector inversion using  XYZ measured by fluxgate magnetometer in UAV 

2021 ◽  
Author(s):  
Arto Karinen
Keyword(s):  
Magnetic Field ◽  
Remanent Magnetization ◽  
Magnetization Vector ◽  
Field Direction ◽  
Magnetic Data ◽  
Total Field ◽  
Main Field ◽  
Vector Inversion ◽  
The Magnetic Field ◽  
Measured Magnetic Field

<p>Traditionally, the inversion of magnetic data assumes the magnetization of the local geology to run parallel to the Earth’s internal magnetic field that is usually modelled using International Geomagnetic Reference Field (IGRF). Assuming the magnetization parallel to the main field, only the total (scalar) magnetic data are the sufficient input for the inversion of source susceptibility.</p><p>Local magnetization may alter from the main field direction in areas of remanent magnetization. Recently, magnetization vector inversion (MVI) using the total field has become an important tool trying to distinguish magnetic data affected by remanenence. Total field as a scalar field exclude all information of the direction of the internal magnetization and more information is required to reveal any remanent magnetization from the main field direction.  Compared to total field using the 3-component XYZ vector magnetic measurements provide more information of the source.  More measurements increase the unambiguous nature of data and may reveal the areas of possible remanence. </p><p>To measure XYZ vector magnetic field we use fluxgate 3-component magnetometer with rigid installation on a fixed-wing UAV. With the help of accurate inertial measurement units the measured magnetic field can be determined in the direction of fixed coordinate system. The components of the measured magnetic field rotated into the geographical coordinate represent the magnetic field at survey area.</p><p>UAV survey provided the data as the input for the inversions. We made the inversion separately for both susceptibility and magnetization vector. Susceptibility inversion means inversion of induced magnetization, i.e., a single component of magnetization parallel to the main field direction. Magnetization vector inversion, however, resolves all three components of magnetization, which may or may not include remanent magnetization in addition to induced one.</p><p>The benefits from utilizing XYZ components of the magnetic field with magnetization inversion seem promising in finding remanenence magnetization.</p><p> </p><p> </p>

Modelling of airborne Full Tensor Magnetic Gradiometry using data from the INFACT project

2020 ◽  
Author(s):  
Jouni Nevalainen ◽  
Elena Kozlovskaya ◽  
Jukka-Pekka Ranta ◽  
Joan Marie Blanco ◽  
Moritz Kirsch ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Quantum Interference ◽  
Remanent Magnetization ◽  
Magnetic Field Gradient ◽  
Magnetic Data ◽  
Joint Analysis ◽  
Horizon 2020 ◽  
Airborne Measurements ◽  
Magnetic Gradiometry ◽  
The Magnetic Field

<p>The measurement of the magnetic field has been a “backbone” geophysical method in mineral exploration since the 17th century. The existing instrumentation that measures Total Magnetic field Intensity (TMI) are a routinely used in ground, borehole and airborne surveys. In the TMI intensity data it is possible to observe certain signatures of magnetised objects, but retrieval of both magnetisation intensity and shape of 3-D magnetised objects from TMI can be difficult due to the vector nature of magnetisation and fundamental non-uniqueness of potential fields interpretation. Moreover, the presence of magnetic material in the host rock and/or presence of remanent magnetisation are challenges for TMI data interpretation.</p><p>Full Tensor Magnetic Gradiometry (FTMG) measurements provide the complete description of the magnetic field and hence an opportunity to get more information on the size, shape and material property of the magnetic rock mass. This is because the signatures in magnetic field originating from a specific magnetic object is observed in all independent components of magnetic field gradient tensor and thus, joint analysis of these tensor components constrains the number of possible magnetic models that fit the same data. In addition, observing the full tensor of magnetic field makes it possible to estimate the remanent magnetization with respect to the induced magnetization field if no a-priori information of remanent magnetization is available.</p><p>Highly sensitive magnetometers based on SQUID (Superconducting QUantum Interference Devices) technology has been successfully adopted in FTMG airborne measurements during the past decade. This achievement has given magnetic methods a new opportunity in terms of purely magnetic data modelling. In our work the benefits of interpretation of tensor airborne FTMG data are demonstrated through forward modelling and inversion with the grid search multiobjective global optimisation. As a case study, we consider airborne FTMG data measured with Supracon® JESSY STAR system in Northern Finland during the INFACT project.</p><p>Acknowledgements: This study has been done in the framework of EU Horizon 2020 funded INFACT project (webpage: https://www.infactproject.eu).</p>

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