Note on the surface impedance and the transmission of radiation through metal slabs

1970 ◽  
Vol 48 (3) ◽  
pp. 370-375 ◽  
Author(s):  
J. F. Cochran
Keyword(s):  
Magnetic Field ◽  
Electric Field ◽  
Surface Impedance ◽  
Uniform Magnetic Field ◽  
Electric Field Distribution ◽  
Skin Depth ◽  
Reflection And Transmission ◽  
Transmission Coefficients ◽  
Field Distributions ◽  
Simple Boundary

An arbitrary electric field distribution in a metal slab in a uniform magnetic field can be written as a linear combination of four functions each of which satisfies Maxwell's equations for particularly simple boundary conditions. In particular, if the slab is thick compared with the skin depth of the radiation, δ, and if (ω/c)δ « 1, then the reflection and transmission coefficients for the slab are proportional to Gx(0), Gy(0), Gx(d), Gy(d) respectively, where Gx(z), Gy(z) are the electric field distributions generated in a slab bounded by the planes z = 0, z = d by a unit alternating magnetic field applied to the surface z = 0 and directed along y.

The effect of nonlocal conductivity on the transmission of microwave radiation through ferromagnetic metals in the field-normal configuration

1986 ◽  
Vol 64 (7) ◽  
pp. 796-821 ◽  
Author(s):  
K. B. Urquhart ◽  
J. F. Cochran
Keyword(s):  
Magnetic Field ◽  
Electric Field ◽  
Microwave Radiation ◽  
Mean Free Path ◽  
Skin Depth ◽  
Charge Carriers ◽  
Surface Scattering ◽  
Field Distributions ◽  
Wide Range ◽  
Diffuse Surface

Procedures are described for the numerical calculation of the electric-field distributions generated in a model ferromagnetic metal slab of thickness d by incident microwave radiation when a static magnetic field is directed along the slab normal and the mean free path ℓ of the charge carriers becomes comparable to, or greater than, the skin depth δ. The model metal is characterized by a local, frequency-dependent permeability; a spherical Fermi surface; and a nonlocal relationship between the current density and the electric-field distribution. The two limiting cases of specular and diffuse scattering of the charge carriers at the slab faces are considered. Electric-field distributions, transmission amplitudes, and surface impedances have been calculated for a wide range of ℓ and d using parameters that simulate nickel. For diffuse surface scattering, the transmission of the magnetically active mode increases at both ferromagnetic resonance (FMR) and cyclotron resonance (CR). A most striking result is the total absence of structure in the magnetic-field dependence of the transmission amplitude near fields corresponding to FMR or to CR for the case of specular scattering. It is demonstrated that very simple formulae provide a good estimate of the free-space transmission amplitudes for both specular and diffuse surface scattering when [Formula: see text] and d/ℓ ≥ 1.

Interaction of plane electromagnetic waves with a moving compressible plasma fluid

1969 ◽  
Vol 47 (4) ◽  
pp. 375-387 ◽  
Author(s):  
H. Fujioka ◽  
F. Nihei ◽  
N. Kumagai
Keyword(s):  
Electric Field ◽  
Electromagnetic Waves ◽  
Surface Charge Density ◽  
Magnetohydrodynamic Wave ◽  
Reflection And Transmission ◽  
Numerical Examples ◽  
Compressible Plasma ◽  
Transmission Coefficients ◽  
Moving Interface ◽  
Magnetoacoustic Waves

The problem of reflection and transmission of plane electromagnetic waves by a semi-infinite compressible plasma fluid moving parallel to its own interface with vacuum is investigated. Solutions are obtained for both incident E wave and H wave. It is found that (i) for the case of incident E wave which excites only two distinct magnetoacoustic waves, the reflection and transmission coefficients add to unity; however, (ii) for the incident H wave which excites only the transverse magnetohydrodynamic wave, both coefficients do not add to unity in general, because of the interaction of the electric field of the transmitted wave with surface charge density at the moving interface. Other interesting features due to the movement of the medium are discussed, and a few numerical examples are given.

Potential and Electric Field Distribution of 220kV Insulator String with a Faulty Insulator under Windage Yaw Condition

2014 ◽  
Vol 521 ◽  
pp. 317-320
Author(s):  
Hui Hui Li ◽  
Zheng Zheng ◽  
Hong Bo Chen ◽  
Huan Bai ◽  
Hua Zhao Zhang ◽  
...  
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Field Strength ◽  
Electric Field ◽  
Field Distribution ◽  
Electric Field Distribution ◽  
Field Distributions ◽  
Space Potential ◽  
Suspension Insulator ◽  
Variation Characteristics

Faulty insulators could appear in the HV transmission line insulator string under the comprehensive effect of electrical, mechanical and environmental factors and they can be detected according to the space potential and electric field distribution variation characteristics around the insulator string. Finite Element Method (FEM) was used to study the potential and electric field distributions of a 220kV suspension insulator string contained a zero-value insulator in windage condition, comparing with a fine insulator string. The results show that the variation of the space potential and electric field distributions of insulator string is the same as that under no windage condition. The curve of synthetic electric field along the central axis around the good insulator string is U-shape. The 10th and 11th insulators from the high-voltage end are the sensitive insulators where the distortion ratio of synthetic field strength is higher than 3%, when a faulty insulator is in the string. This result can provide preferences for the online detection of faulty insulators.

scholarly journals Effect of a stochastic electric field on plasma confinement in FTU

2016 ◽  
Vol 31 (02) ◽  
pp. 1650005 ◽  
Author(s):  
Roberto Martorelli ◽  
Giovanni Montani ◽  
Nakia Carlevaro
Keyword(s):  
Magnetic Field ◽  
Experimental Data ◽  
Electric Field ◽  
Uniform Magnetic Field ◽  
Planck Equation ◽  
Plasma Confinement ◽  
Stochastic Field ◽  
Magnetically Confined ◽  
The Magnetic Field ◽  
Plasma Profile

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].

DETERMINATION OF THE ELECTRICAL CONDUCTIVITY OF THE SEA BED IN SHALLOW WATERS

Geophysics ◽  
1968 ◽  
Vol 33 (6) ◽  
pp. 995-1003 ◽  
Author(s):  
Peter R. Bannister
Keyword(s):  
Magnetic Field ◽  
Electric Field ◽  
Sea Water ◽  
Field Measurements ◽  
Bottom Layer ◽  
Dipole Antenna ◽  
Skin Depth ◽  
Noise Component ◽  
Sea Bed ◽  
Magnetic Field Measurements

The electric and magnetic field components produced by horizontal dipole antennas (both electric and magnetic) located within the upper layer of a two‐layer conducting earth are derived for the quasi‐near range. This range is defined as that in which the measurement distance is much greater than an earth skin depth but much less than a free‐space wavelength. Ionospheric effects are neglected. It is assumed that the transmitting and receiving anterenna depths are much less than their horizontal separation, and that the fields in the horizontal direction vary only slightly in a distance of one skin depth. It is well known that if the conductivity and thickness of the first layer (sea water) are known, the conductivity of the bottom layer (the sea bed) may be determined from magnetic field measurements alone. However, when extremely low‐frequency magnetic field measurements are performed at sea, the movement of the magnetic field sensors in the static magnetic field of the earth (which is many times stronger than the field to be measured) introduces a very strong noise component. It is argued that electric field measurements are preferable because the induced noise component is smaller. It is shown that the sea bed conductivity may be determined by measuring only the horizontal electric field components produced by a subsurface horizontal magnetic dipole antenna.

scholarly journals Surface impedance of electromagnetic field excited by a grounded horizontal antenna in the Earth–ionosphere waveguide

2019 ◽  
pp. 181-189
Author(s):  
E. D. Tereshchenko ◽  
P. E. Tereshchenko
Keyword(s):  
Magnetic Field ◽  
Electromagnetic Field ◽  
Surface Impedance ◽  
Low Frequency ◽  
Wave Impedance ◽  
Skin Layer ◽  
Skin Depth ◽  
Plane Waveguide ◽  
The Earth ◽  
Horizontal Antenna

Analytical formulas for the tangential components of extremely-low-frequency (ELF) electromagnetic field in the Earth–ionosphere plane waveguide excited by a grounded linear horizontal antenna are obtained. The behavior of surface impedance is studied as a function of electrodynamic characteristics of the waveguide and the distance from the source. It is shown that surface impedance coincides with the plane wave impedance on the Earth’s surface at distances from the source larger than the skin depth provided that the skin layer is thinner than double the waveguide’s height. The influence of the ionosphere on the amplitude of the ELF and lower-frequency magnetic field and, thus, on the impedance at the distances shorter than two ionospheric heights is theoretically substantiated. This type of effect was observed in the experiments conducted on the Kola Peninsula where the low conductivity of the Earth allowed the detection of the effect of the ionosphere on the amplitude of the magnetic field in the low-frequency band.

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