Magnetic Field Inversion – the cost of freedom

2019 ◽  
Vol 2019 (1) ◽  
pp. 1-5
Author(s):  
B. Vital Leonardo ◽  
Foss Clive ◽  
C. Oliveira Vanderlei ◽  
C. F. Barbosa Valeria
1990 ◽  
Vol 165-166 ◽  
pp. 1103-1104 ◽  
Author(s):  
A.M. Grishin ◽  
A.Yu. Martynovich ◽  
S.V. Yampolskii

Author(s):  
V Lesur ◽  
F Vervelidou

Summary We investigate to which extent the radially averaged magnetisation of the lithosphere can be recovered from the information content of a spherical harmonic model of the generated magnetic field when combined with few simple hypotheses. The results obtained show firstly that a hypothesis of magnetisation induced by a field of internal origin, even over a localised area, is not sufficient to recover uniquely the radially averaged magnetisation and, secondly, that this magnetisation can be recovered when a constant magnetisation direction is assumed. An algorithm to recover the magnetisation direction and distribution is then described and tested over a synthetic example. It requires to introduce a cost function that vanishes when estimated in a system of coordinates with its Z axis aligned with the magnetisation direction. Failing to find a vanishingly small value for the cost function is an indication that a constant magnetisation direction is not a valid hypothesis for the studied magnetic field model. The range of magnetisation directions that are compatible with the magnetic field model and a given noise level, can also be estimated. The whole process is illustrated by analysing a local, isolated maximum of the Martian magnetic field.


2006 ◽  
Vol 84 (9) ◽  
pp. 845-855 ◽  
Author(s):  
S Winter ◽  
C Mok ◽  
A Kumarakrishnan

We discuss the design and construction of a Faraday isolator for diode laser spectroscopy using commercially available components. The design involves modelling the magnetic field of an assembly of cylindrical magnets and verifying the predictions using a sensor. We obtain an isolation ratio for optical feedback of ∼35 dB at a wavelength of 780 nm. The cost is approximately one-fourth the cost of an equivalent commercially available device. We expect that the design can be widely used in experiments in laser spectroscopy and in advanced undergraduate laboratory experiments.PACS Nos.: 01.50.Pa, 32.80.Pj, 39.25.+k, 42.62.Fi


2013 ◽  
Vol 694-697 ◽  
pp. 1179-1182
Author(s):  
Yi Lai Ma ◽  
Li Lin ◽  
Kai Wen Jiang ◽  
Xu Lin Zhao

Magnetic flux leakage is one type of electromagnetic nondestructive testing (NDT) which is widely utilized in the testing the integrity of drill pipe in the field. In this paper, the 3D model of excitation unit is completely built and analyzed by ANSYS software. The magnetic field of drill pipe in the combination of full excitation device is showed by ANSYS software instead of the physic experiments which increases the efficiency tremendously and decreases the cost and achieves the anticipated desire. It is considered that this technique can provide the theoretical basis of drill pipe excitation device and the magnetic flux leakage testing of drill pipe.


MRS Advances ◽  
2015 ◽  
Vol 1 (17) ◽  
pp. 1137-1148 ◽  
Author(s):  
Yoshikazu Sakai ◽  
Takaaki Hibaru ◽  
Kiyoshi Miura ◽  
Akira Matsuo ◽  
Koushi Kawaguchi ◽  
...  

ABSTRACTOne of the authors developed the high strength and high conductivity Cu-24 wt% Ag alloy as a conductor material for high field magnets twenty years ago.Wire and sheet of the alloy have been used as a conductor material for pulsed magnets or resistive magnets of the high magnetic field facilities of each country. However, the alloy required large quantities of Ag addition to achieve high strength. The cost performance and workability of the alloy were not good for that. So, we investigated possibility of low Cu-Ag alloy for decreasing in material cost and improving in workability. We succeeded in the development of the Cu-6 wt% Ag alloy by the new heat treatment which is superior to the characteristic of the Cu-24 wt% Ag alloy even if the amount of Ag content is decreased in 1/4.At present, we make a lot of high field pulsed magnets by using the Cu-6 wt% Ag wire manufactured industrially, and do that magnetic field experiment and are getting good results at the ISSP, the university of Tokyo. We will talk about the characteristic, new heat treatment method and the manufacturing process of the conductor material for the Cu-6 wt% Ag alloy.


2019 ◽  
Vol 47 (1) ◽  
pp. 129-131
Author(s):  
O.O. Tsareva ◽  
V.Yu. Popov ◽  
H.V. Malova ◽  
E.P. Popova ◽  
M.V. Podzolko ◽  
...  

Recent observations, such as the magnetic field strength decrease, a magnetic poles shifts and the South Atlantic anomaly increase, may indicate the beginning of the Earth’s magnetic field inversion. According to the geomagnetic dynamo model, the dipole component of the magnetic field is zeroed at the inversion time, and the quadrupole one becomes dominant. To assess the occurrence of radiation hazards on the Earth’s surface and in near-Earth space at the time of magnetic field inversion, a numerical model was developed that made it possible to compare the GCR and SCR fluxes (at minima and maxima of solar activity) penetrating the Earth (taking into account the atmosphere) and the ISS in periods of the dipole and quadrupole fields dominance. It was found that during the period of inversion the flow of GCR (high-energy particles) can increase no more than three times over the entire surface of the Earth and the radiation dose will not exceed permissible one for man. Also, a change of the magnetic field configuration will redistribute areas of increased radiation on the Earth’s surface (today these are the poles of the Earth), which can adversely affect people’s health in these areas.


Author(s):  
Xu Jin ◽  
Guo Yilin

Background: As wireless energy transmission technology advances, the demand for energy directional transmission increases. Objective: Transfer of energy in the specified direction and increase in transmission power. Methods: A novel three-coil transmitting structure was proposed, which can transmit energy to a specified single or multiple space regions, and enhance the magnetic field strength in a single direction by magnetic field vector synthesis to improve the transmission power. Results: Combined with Mathcad numerical calculation and Maxwell simulation analysis, the experimental platform was built and the magnetic focusi of the proposed novel structure was experimentally verified. Conclusion: The novel emission structure can effectively perform directional energy transmission and increase the transmission power by 2~3 times in a single direction at the cost of 10%~15% efficiency loss.


2009 ◽  
Vol 7 (3) ◽  
pp. 423-428 ◽  
Author(s):  
J. Tomek ◽  
A. Platil

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