In-situ electric field and current density in Japanese male and female models for uniform magnetic field exposures

2009 ◽  
Vol 135 (4) ◽  
pp. 272-275 ◽  
Author(s):  
A. Hirata ◽  
K. Wake ◽  
S. Watanabe ◽  
M. Taki
2012 ◽  
Vol 1434 ◽  
Author(s):  
Kohei Higashikawa ◽  
Kei Shiohara ◽  
Masayoshi Inoue ◽  
Takanobu Kiss ◽  
Masateru Yoshizumi ◽  
...  

ABSTRACTTo enhance a global critical current in a superconductor, it is indispensable to understand current limiting factors and their influence on such a critical current. From this point of view, we have investigated in-plane distribution of local critical current density and its electric field criterion in a thin-film superconductor by using scanning-Hall probe microscopy. In a remanent state, after the application of sufficiently high magnetic field to a sample, current flows at critical current density according to the critical state model. Such distribution of current density was estimated from that of measured magnetic field using the Biot-Savart law. Furthermore, the corresponding electric field criterion was evaluated from the relaxation of such remanent magnetic field by considering Faraday’s law. This means that we could estimate in-plane distribution of local critical current density as a function of electric field criterion in a nondestructive manner. This characterization method would be very helpful for finding current limiting factors in a thin-film superconductor and their influence on its global current density versus electric field properties which would usually be obtained by four-probe method.


Author(s):  
Heinz London ◽  
Frederick Alexander Lindemann

In previous papers of F. and H. London supraconductivity has been described as a phenomenon, in which the current density is not connected with the electric field, as in normal conductors, but depends on magnetic field strength according to the equation Λ c curl J = - H with B = H and with Λ = m / ne 2, a new characteristic constant which contains the number n of supraconducting electrons. the behaviour of the electric field is not completely determined by this equation. Using Maxwell's induction law one can conclude from (1) only that Λ c curl j = c curl E or Λj = E + grand μ, where the physical signifance of grad μ is yet unknown.


2016 ◽  
Vol 31 (02) ◽  
pp. 1650005 ◽  
Author(s):  
Roberto Martorelli ◽  
Giovanni Montani ◽  
Nakia Carlevaro

We discuss a stochastic model for the behavior of electrons in a magnetically confined plasma having axial symmetry. The aim of the work is to provide an explanation for the density limit observed in the Frascati Tokamak Upgrade (FTU) machine. The dynamical framework deals with an electron embedded in a stationary and uniform magnetic field and affected by an orthogonal random electric field. The behavior of the average plasma profile is determined by the appropriate Fokker–Planck equation associated to the considered model and the disruptive effects of the stochastic electric field are shown. The comparison between the addressed model and the experimental data allows to fix the relevant spatial scale of such a stochastic field. It is found to be of the order of the Tokamak micro-physics scale, i.e. few millimeters. Moreover, it is clarified how the diffusion process outlines a dependence on the magnetic field as [Formula: see text].


IEEE Access ◽  
2019 ◽  
Vol 7 ◽  
pp. 184320-184331 ◽  
Author(s):  
Yinliang Diao ◽  
Jose Gomez-Tames ◽  
Essam A. Rashed ◽  
Robert Kavet ◽  
Akimasa Hirata

Energies ◽  
2020 ◽  
Vol 13 (14) ◽  
pp. 3635
Author(s):  
Junqing Lan ◽  
Akimasa Hirata

This study computationally evaluates the effect of loudspeakers on the in situ electric field in a driver body model exposed to the magnetic field from a wireless power transfer (WPT) system in an electric vehicle (EV), one with a body made of carbon fiber reinforced plastic (CFRP) and the other made with aluminum. A quasi-static two-step approach was applied to compute the in situ electric field. The computational results showed that the magnetic field distribution generated by the WPT is significantly altered around the loudspeakers, and shows obvious discontinuity and local enhancement. The maximum spatial-average magnetic field strength in the driver’s body was increased by 11% in the CFRP vehicle. It was 2.25 times larger than the reference levels (RL) prescribed in the International Commission of Non-Ionizing Radiation Protection (ICNIRP) guidelines in 2010. In addition, we found that the in situ electric field computed by the line- and volume-averaging methods were stable if the top 0.1% voxels are excluded. The maximum value was well below the basic restriction (BR) of the ICNIRP guidelines. Nevertheless, the presence of the loudspeaker led to increments in the electric field strength in parts of the human body, suggesting the potential influence of permissible transmitting power in the WPT system. The maximum electric field strength in the thigh and buttock with the woofer, increased by 27% in the CFRP vehicle. The arm value was up to 3 times higher than that obtained without the tweeter in the aluminum vehicle. Moreover, this study found that the maximum electric field strength depended on the location of the loudspeaker with respect to the WPT system and the separation from the driver model. Therefore, the loudspeaker should be considered when evaluating the maximum in situ electric field strength in the vehicle body design stage.


Geophysics ◽  
1991 ◽  
Vol 56 (8) ◽  
pp. 1140-1152 ◽  
Author(s):  
P. W. Walker ◽  
G. F. West

An integral equation solution for electromagnetic (EM) scattering by a thin plate robustly models scattering in either perfectly resistive, very resistive, or conducting host media. Because the solution is not restricted to modeling certain ranges of host conductivity, it can be used to model scattering over the large ranges in conductivity encountered in geophysics. The solution is developed around a pair of coupled integral equations for the scattering distributions on the plate. In one equation, the scattering distribution is the scalar potential set up by the scattered charge distribution. In the other, it is the component of the scattered magnetic field perpendicular to the plate. The equations are solved numerically using the Galerkin method with simple polynomial basis functions. To find the fields scattered by the conductor, the scattered current density is first calculated from the scalar potential and the magnetic field. The scattered fields can then be found by integrating over the scattered current density. To test the solution, we model horizontal loop EM responses with our solution and compare the results with those from two established integral equation solutions. One of these solutions models pure induction and is used to test our solution when the host is perfectly resistive. Agreement with this solution is very good. Comparisons with the other solution, an electric field integral equation, tests our solution when the host medium is conductive. Agreement with the latter solution is good where induction is not too strong: i.e., where the electric‐field solution is known to work well. Our solution therefore can accurately model EM scattering by a plate in a host medium with any conductivity.


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