scholarly journals Conical two dimensional plasma acceleration at resonance absorption

1983 ◽  
Vol 1 (2) ◽  
pp. 107-119 ◽  
Author(s):  
G. W. Kentwell
Keyword(s):  
Collision Frequency ◽  
Analytic Solutions ◽  
Resonance Absorption ◽  
Angle Of Incidence ◽  
Plasma Acceleration ◽  
Wave Processes ◽  
Transient Wave ◽  
At Resonance ◽  
Nonlinear Force ◽  
Density Scale

By employing analytic solutions for the electromagnetic field at resonance absorption, first derived by Denisov, the total nonlinear force, in the plane of incidence has been evaluated. This 2-D force results in a conical type emission towards the vacuum and into the plasma which depends critically on the collision frequency and the density scale length. It is found that, for neodynium glass laser intensities of 1014 W/cm2, keV ions can be produced by nonlinear force acceleration. The analysis is limited by the following requirements: the dielectric constant varies linearly with distance, the angle of incidence is not too small and most importantly self consistent and transient wave processes occur at a later time and are neglected.

scholarly journals Study of the Propagation Characteristics of Terahertz Waves in a Collisional and Inhomogeneous Dusty Plasma with a Ceramic Substrate and Oblique Angle of Incidence

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Qingwen Rao ◽  
Guanjun Xu ◽  
Pengfei Wang ◽  
Zhengqi Zheng
Keyword(s):  
Electron Density ◽  
Dusty Plasma ◽  
Collision Frequency ◽  
Incident Angle ◽  
Ceramic Substrate ◽  
Dust Particles ◽  
Angle Of Incidence ◽  
Oblique Angle ◽  
Terahertz Waves ◽  
Thz Wave

In this paper, the propagation properties of a terahertz (THz) wave in a collisional and inhomogeneous dusty plasma with a ceramic substrate and oblique angle of incidence are studied using the scattering matrix method. The influence of the various corresponding parameters, such as the frequency of the THz wave, angle of incidence, electron density, radius and density of the dust particles, and the collision frequency, on the absorbance and transmittance is calculated. The results of the simulation indicate that an increase in the wave frequency increases the transmittance and decreases the absorbance. Moreover, the absorbance of a THz wave in a dusty plasma with a ceramic substrate increases with an increase in the incident angle, maximum electron density, coefficient of steepness, density and radius of the dust particles, and collision frequency. These results provide an important theoretical basis for the problem of communication blackout between ground and spacecraft.

scholarly journals On the convection of ionospheric density features

2019 ◽  
Vol 37 (2) ◽  
pp. 201-214
Author(s):  
John D. de Boer ◽  
Jean-Marc A. Noël ◽  
Jean-Pierre St.-Maurice
Keyword(s):  
Collision Frequency ◽  
Analytic Solutions ◽  
The Other ◽  
Density Difference ◽  
Density Gradients ◽  
Scale Invariant ◽  
The Real ◽  
Altitude Dependence ◽  
Density Enhancement ◽  
Auroral Arcs

Abstract. We investigate whether the boundaries of an ionospheric region of different density than its surroundings will drift relative to the background E×B drift and, if so, how the drift depends on the degree of density enhancement and the altitude. We find analytic solutions for discrete circular features in a 2-D magnetised plasma. The relative drift is proportional to the density difference, which suggests that where density gradients occur they should tend to steepen on one side of a patch while they are weakened on the other. This may have relevance to the morphology of polar ionospheric patches and auroral arcs, since the result is scale-invariant. There is also an altitude dependence which enters through the ion-neutral collision frequency. We discuss how the 2-D analytic result can be applied to the real ionosphere.

scholarly journals Resonant waves and localization phenomena in lattices

2019 ◽  
Vol 377 (2156) ◽  
pp. 20190110
Author(s):  
Sagdulla A. Abdukadirov ◽  
Mark V. Ayzenberg-Stepanenko ◽  
Gregory G. Osharovich
Keyword(s):  
Three Dimensional ◽  
Wave Processes ◽  
Theme Issue ◽  
Hexagonal Cell ◽  
Transient Wave ◽  
Structured Media ◽  
Different Types ◽  
Mass Spring ◽  
Square Cell ◽  
Dynamic Phenomena

Transient wave processes in mass-spring lattices excited by point oscillating sources are studied. Dispersion properties of uniform periodic three-dimensional (3D) square-cell and two-dimensional (2D) hexagonal-cell lattices including revealed star-shaped localization phenomena are analysed. The resonant-like waves and localization-like patterns in non-uniform lattices possessing predetermined and randomly distributed defects are numerically examined in order to identify the sensitivity of star-shape forms to different types of defects. This article is part of the theme issue ‘Modelling of dynamic phenomena and localization in structured media (part 1)’.

scholarly journals Design of Cold Plasma Based Ternary Photonic Crystal for Microwave Applications

2021 ◽  
Author(s):  
Narendra Kumar ◽  
Sonu Kaliramna ◽  
Mahima Singh
Keyword(s):  
Photonic Crystal ◽  
High Frequency ◽  
Collision Frequency ◽  
Angle Of Incidence ◽  
Photonic Bandgaps ◽  
Frequency Spectra ◽  
Unit Cells ◽  
Ternary Photonic Crystal ◽  
1D Photonic Crystal ◽  
Transmission And Reflection

Abstract In this paper, we propose a Silicon/Plasma/Air ternary 1D photonic crystal, whose transmission and reflection properties have been studied. We draw the transmittance and reflectance versus frequency spectra in microwave region (GHz) for RHP Plasma based ternary PC by changing the angle of incidence for a fixed value of unit cells, magnetic field, layer thickness, collision frequency, and electron density. It is observed that with increase in angle of incidence, there is increase in photonic bandgap obtained in low and high frequency regions. With increase in angle, the photonic bandgaps shift towards higher frequencies. At angle 89° there are multiple sharp peaks of transmission are obtained. By comparing this ternary PC with a binary silicon/plasma PC, it is observed that this proposed PC has higher number of bands for smaller angles which makes them a good candidate for making multi-channel tunable filters, and for higher angle it behaves like broadband reflector. The proposed structure may also be a good candidate for many applications in making other microwave devices.

The effect of a time varying collision frequency on a radio wave obliquely incident on the lower ionosphere

1976 ◽  
Vol 348 (1653) ◽  
pp. 245-263 ◽  
Keyword(s):  
Radio Wave ◽  
Collision Frequency ◽  
Modulation Frequency ◽  
Average Power ◽  
Lower Ionosphere ◽  
Angle Of Incidence ◽  
Disturbed Region ◽  
Quartic Equation ◽  
Obliquely Incident ◽  
Cross Modulation

The phenomenon of ionospheric cross-modulation occurs when a ‘wanted’ radio wave passes through a region of the ionospheric plasma where a powerful modulated ‘disturbing’ radio wave is strongly absorbed. Many previous studies have assumed that the wanted wave is vertically incident and, in some cases, that the ionosphere is isotropic. The theory is studied here for an obliquely incident wanted wave propagating through an anisotropic ionosphere. The Booker quartic equation is used to find the modulation transferred to the wanted wave, and how it depends on height, angle of incidence, azimuth and radio frequency. It is assumed that the disturbing wave has a sinusoidal amplitude modulation so that the collision frequency in the disturbed region varies periodically with the modulation frequency. The physical processes that occur in various situations are reviewed. It is found that many of the results from the simpler theories still apply, but some new effects are found. For example, there can be a marked difference in the modulation transferred to two ordinary (or two extraordinary) wanted waves with the same angle of incidence, one travelling obliquely upwards, and the other downwards through the disturbed region. It is found that an increase in the average power of the disturbing wave does not necessarily imply a corresponding increase in the modulation transferred to the wanted wave. The radio engineer who requires an accurate assessment of cross-modulation as a possible source of interference in communications could apply some methods of this paper with the aid of modern computers.

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