Density-modulation effects on the propagation of an electromagnetic wave in a plasma

1992 ◽  
Vol 48 (2) ◽  
pp. 209-214 ◽  
Author(s):  
Maurizio Lontano ◽  
Nicolai Lunin
Keyword(s):  
Electromagnetic Wave ◽  
Reflection Coefficient ◽  
Spatial Modulation ◽  
Transmission Spectra ◽  
Density Profiles ◽  
Plasma Slab ◽  
Density Modulation ◽  
Transparent Plasma ◽  
Single Plasma ◽  
Linear Cut

The propagation of an electromagnetic wave through a transparent plasma characterized by a spatial modulation of the density in the direction of propagation is analysed by computing the reflection coefficient of a single plasma slab and then that relevant to a set of many identical or slightly different slabs. The transmission spectra relevant to different density profiles of a single slab are computed to show the effects of (a) the density gradient, (b) a slight non-uniformity among adjacent slabs and (c) plasma modulation on the linear cut-off.

Radar Absorbing Materials Based on Metamaterials

2010 ◽  
Vol 75 ◽  
pp. 215-223
Author(s):  
Andrey Nikolayevich Lagarkov ◽  
Vladimir Nikolayevich Kisel ◽  
Vladimir Nikolayevich Semenenko
Keyword(s):  
Electromagnetic Wave ◽  
Reflection Coefficient ◽  
Frequency Band ◽  
Radar Absorbing Material ◽  
Wide Range ◽  
Absorbing Materials ◽  
Different Types ◽  
Absorbing Material ◽  
Wave Incidence

The use of metamaterial for design of radar absorbing material (RAM) is discussed. The typical features of the frequency dependencies of , , ,  of composites manufactured of different types of resonant inclusions are given as an example. The RAM characteristics obtained by the use of the composites are given. It is shown that it is possible to use for RAM design the metamaterials with both the positive values of ,  and negative ones. Making use of the frequency band with negative  and  it is possible to create a RAM with low reflection coefficient in a wide range of the angles of electromagnetic wave incidence.

scholarly journals Model of Е-polarized wave propagation in a multilayer dielectric structure

2021 ◽  
Vol 2021 (3) ◽  
pp. 111-118
Author(s):  
P.I. Zabolotnyi ◽  
Keyword(s):  
Dielectric Constant ◽  
Electromagnetic Wave ◽  
Reflection Coefficient ◽  
Incidence Angle ◽  
Relative Dielectric Constant ◽  
Normal Incidence ◽  
Dielectric Constants ◽  
Dielectric Structure ◽  
Range Of Variation ◽  
Multilayer Dielectric

This paper addresses the determination of the dielectric constant of multilayer dielectric structures by radiowave interferometry. In the general case, in interferometry measurements to one measured value of the reflection coefficient there may correspond an infinity of dielectric constants. This ambiguity may be resolved by first determining the effect of different parameters of the probing electromagnetic wave on the reflection coefficient. In particular, it is important to have a preliminary estimate of the effect of the incidence angle and the polarization on the range of variation of the reflection coefficient with the variation of one of the structure parameters. This paper considers the case where a plane E-polarized electromagnetic wave, i.e. a wave whose magnetic field is perpendicular to the incidence plane, is incident on a multilayer dielectric structure. The aim of this work is to develop a model of the propagation of an E-polarized electromagnetic wave through a multilayer dielectric structure at an arbitrary incidence angle and to determine the range of variation of the reflection coefficient with the variation of the dielectric constants of the layers. The paper presents a model of the propagation of an E-polarized electromagnetic wave in a two-layer dielectric structure. A metal base, which is an ideal conductor, underlies the structure. The electromagnetic wave is incident from the air at an arbitrary incidence angle. Based on the model, a method is proposed for measuring the relative dielectric constant and the dielectric loss tangent. It is shown that at a normal incidence the reflection coefficient magnitude is the same both for H- and E-polarization. Because of this, determining the relative dielectric constant and the loss tangent from the measured reflection coefficient magnitude calls for measurements not only at a normal incidence, but also at an oblique incidence, at which the reflection coefficient magnitudes will be different for H- and E-polarization.

Reflection Properties of Electromagnetic Wave in a Bounded Plasma Slab

2010 ◽  
Vol 38 (12) ◽  
pp. 3348-3355 ◽  
Author(s):  
C. X. Yuan ◽  
Z. X. Zhou ◽  
H. G. Sun
Keyword(s):  
Electromagnetic Wave ◽  
Bounded Plasma ◽  
Plasma Slab

scholarly journals Alkaline exospheres of exoplanet systems: evaporative transmission spectra

2020 ◽  
Vol 497 (4) ◽  
pp. 5271-5291 ◽  
Author(s):  
Andrea Gebek ◽  
Apurva V Oza
Keyword(s):  
High Resolution ◽  
Cross Sections ◽  
Planetary Atmospheres ◽  
Hydrostatic Equilibrium ◽  
Transmission Spectra ◽  
Absorption Cross ◽  
Density Profiles ◽  
Hot Jupiters ◽  
Exoplanet Systems ◽  
Sodium And Potassium

ABSTRACT Hydrostatic equilibrium is an excellent approximation for the dense layers of planetary atmospheres, where it has been canonically used to interpret transmission spectra of exoplanets. Here, we exploit the ability of high-resolution spectrographs to probe tenuous layers of sodium and potassium gas due to their formidable absorption cross-sections. We present an atmosphere–exosphere degeneracy between optically thick and optically thin mediums, raising the question of whether hydrostatic equilibrium is appropriate for Na i lines observed at exoplanets. To this end we simulate three non-hydrostatic, evaporative, density profiles: (i) escaping, (ii) exomoon, and (iii) torus to examine their imprint on an alkaline exosphere in transmission. By analysing an evaporative curve of growth, we find that equivalent widths of $W_{\mathrm{Na D2}} \sim 1{\!-\!} 10\, \mathrm{m\mathring{\rm A}}$ are naturally driven by evaporation rates ∼103−105 kg s−1 of pure atomic Na. To break the degeneracy between atmospheric and exospheric absorption, we find that if the line ratio is D2/D1 ≳ 1.2 the gas is optically thin on average roughly indicating a non-hydrostatic structure of the atmosphere/exosphere. We show this is the case for Na i observations at hot Jupiters WASP-49b and HD189733b and also simulate their K i spectra. Lastly, motivated by the slew of metal detections at ultra-hot Jupiters, we suggest a toroidal atmosphere at WASP-76b and WASP-121b is consistent with the Na i data at present.

Durchgang von Mikrowellen durch ebene Plasmaschichten

1962 ◽  
Vol 17 (1) ◽  
pp. 59-64
Author(s):  
K. Hain ◽  
M. Tutter
Keyword(s):  
Magnetic Field ◽  
Electromagnetic Wave ◽  
Static Magnetic Field ◽  
Plane Electromagnetic Wave ◽  
Reflection And Transmission ◽  
Plasma Slab ◽  
Plane Plasma

The reflection and transmission of a plane electromagnetic wave propagating through a plane plasma slab with and without a static magnetic field is computed.

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