Numerical Approach for Computation of Electromagnetic Shielding

Disturbing magnetic field (so-called magnetic smog) can be in certain areas suppressed by shielding jacket. Disturbing field is possible to be “lead away” from the shielded area with the use of jacket made of materials with high magnetic permeability (so-called passive shielding, or flux-entrapment shielding). If the disturbing field is time-variable, eddy currents are induced into electrically conductive jacket. Magnetic field generated by these eddy currents suppress the disturbing field (this is called active shielding, or lossy magnetic shielding). Both of these principles can be applied altogether (this is called combined shielding). Presented paper states numerical approach to shielding jacket design and is an introduction to following solution of a real problem of magnetic shielding when the disturbing magnetic field is space-time complicated. Effective design of the magnetic shielding should then be formulated as an optimization task.

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FERROMAGNETS WITH EDDY CURRENTS AND PINNING EFFECTS: THEIR THERMODYNAMICS AND ANALYSIS

Mathematical Models and Methods in Applied Sciences ◽

10.1142/s0218202511004976 ◽

2011 ◽

Vol 21 (01) ◽

pp. 29-55 ◽

Cited By ~ 10

Author(s):

TOMÁŠ ROUBÍČEK ◽

GIUSEPPE TOMASSETTI

Keyword(s):

Magnetic Field ◽

Domain Wall ◽

Parabolic Equations ◽

Eddy Currents ◽

Continuum Theory ◽

Nonlinear Parabolic Equations ◽

Electrically Conductive ◽

Existence Of Weak Solutions ◽

Nonlinear Parabolic ◽

Domain Wall Pinning

Existence of weak solutions is proved for a system of nonlinear parabolic equations/inequalities describing evolution of magnetization, temperature, magnetic field, and electric field in electrically-conductive unsaturated ferromagnets. The system is derived from a recently-proposed thermodynamically-consistent continuum theory for the ferro/paramagnetic transition. Besides the standard viscous-like damping, dissipation due to eddy currents and domain-wall pinning is considered.

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HEATING RATE PREDICTION FOR INDUCTION WELDING MAGNETIC SUSCEPTORS

10.12783/asc36/35740 ◽

2021 ◽

Author(s):

ROMAIN G. MARTIN ◽

CHRISTER JOHANSSON ◽

JASON R. TAVARES ◽

MARTINE DUBÉ

Keyword(s):

Magnetic Field ◽

Heating Rate ◽

Surface Area ◽

Magnetic Particles ◽

Eddy Currents ◽

Field Amplitude ◽

Hysteresis Curve ◽

Heating Rates ◽

Electrically Conductive ◽

Thermoplastic Matrix

Induction welding involves generating heat by applying an oscillating magnetic field, which produces eddy currents and Joule losses in an electrically-conductive material or hysteresis losses in a magnetic material. Most applications rely on eddy currents generation as composites are often made of electrically-conductive carbon fibres. However, in other applications, heat can be produced by a magnetic susceptor located at the weld interface of the parts to be joined. Composite films of magnetic particles dispersed in a thermoplastic matrix can serve as magnetic susceptors. Magnetic particles selection relies on various parameters that must be thoroughly defined beforehand. Firstly, the applied magnetic field amplitude and frequency is calculated, based on the generated current and the induction coil geometry. Secondly, the thermoplastic matrix is characterized, mainly with DSC measurements, to define its processing window. Finally, the magnetic properties of the particles are measured – for instance using a vibrating sample magnetometer (VSM) – to obtain the hysteresis curve for the applied field. The enclosed surface area of the hysteresis curve (i.e. absorbed energy density) is critical, as low hysteresis materials (i.e. soft magnets) will not dissipate enough heat, while high hysteresis materials (i.e. hard magnets) cannot be fully exploited as the saturation hysteresis is not reached within the used field amplitude. A methodology to approximate the hysteresis enclosed surface area with limited data is proposed, helping to anticipate the heating rate of a susceptor candidate material. Based on these parameters, the theoretical heating rates of three magnetic susceptor materials (magnetic particles of iron, nickel and magnetite) for induction welding are calculated. They are verified experimentally by comparing with the hysteresis analysis and by measuring the temperature evolution of samples made of polypropylene containing the magnetic particles.

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METHOD OF SYNTHESIS OF CLOSED-LOOP SYSTEMS OF ACTIVE SHIELDING MAGNETIC FIELD OF POWER TRANSMISSION LINES

Tekhnichna Elektrodynamika ◽

10.15407/techned2016.04.008 ◽

2016 ◽

Vol 2016 (4) ◽

pp. 8-10 ◽

Cited By ~ 1

Author(s):

B.I. Kuznetsov ◽

◽

A.N. Turenko ◽

T.B. Nikitina ◽

A.V. Voloshko ◽

...

Keyword(s):

Magnetic Field ◽

Transmission Lines ◽

Closed Loop ◽

Power Transmission ◽

Power Transmission Lines ◽

Closed Loop Systems ◽

Active Shielding

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Jeffrey fluid effect on free convective over a vertically inclined plate with magnetic field: A numerical approach

10.1063/1.5033258 ◽

2018 ◽

Author(s):

J. Anand Rao ◽

R. Srinivasa Raju ◽

C. D. Bucchaiah

Keyword(s):

Magnetic Field ◽

Numerical Approach ◽

Jeffrey Fluid ◽

Inclined Plate

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Weakly Nonlinear Magnetic Convection in a Nonuniformly Rotating Electrically Conductive Medium Under the Action of Modulation of External Fields

East European Journal of Physics ◽

10.26565/2312-4334-2020-2-01 ◽

2020 ◽

Keyword(s):

Magnetic Field ◽

Angular Velocity ◽

Landau Equation ◽

Temperature Modulation ◽

External Fields ◽

Ginzburg Landau ◽

Electrically Conductive ◽

Weakly Nonlinear ◽

Conductive Fluid ◽

Ginzburg Landau Equations

In this paper we studied the weakly nonlinear stage of stationary convective instability in a nonuniformly rotating layer of an electrically conductive fluid in an axial uniform magnetic field under the influence of: a) temperature modulation of the layer boundaries; b) gravitational modulation; c) modulation of the magnetic field; d) modulation of the angular velocity of rotation. As a result of applying the method of perturbation theory for the small parameter of supercriticality of the stationary Rayleigh number nonlinear non-autonomous Ginzburg-Landau equations for the above types of modulation were obtaned. By utilizing the solution of the Ginzburg-Landau equation, we determined the dynamics of unsteady heat transfer for various types of modulation of external fields and for different profiles of the angular velocity of the rotation of electrically conductive fluid.

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