scholarly journals Twisted Waves near a Plasma Cutoff

Symmetry ◽  
2022 ◽  
Vol 14 (1) ◽  
pp. 146
Author(s):  
José Tito Mendonça ◽  
Camilla Willim ◽  
Jorge Vieira
Keyword(s):  
Wave Propagation ◽  
Normal Incidence ◽  
Pulse Envelope ◽  
Nonuniform Plasma ◽  
Mechanical Spring ◽  
Wave Properties

This work considers twisted wave propagation in inhomogeneous and unmagnetised plasma, and discusses the wave properties in the cutoff region. The qualitative differences between twisted waves described by a single Laguerre–Gauss (LG) mode, and light springs resulting from the superposition of two or more LG modes with different frequency and helicity are studied. The peculiar properties displayed by these waves in the nonuniform plasma are discussed. The pulse envelope of a light-spring shows a contraction at reflection, which resembles that of a compressed mechanical spring. The case of normal incidence is examined, and nonlinear ponderomotive effects are discussed, using theory and simulations.

scholarly journals Anomalous Anderson localization behavior in gain-loss balanced non-Hermitian systems

Nanophotonics ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 443-452
Author(s):  
Tianshu Jiang ◽  
Anan Fang ◽  
Zhao-Qing Zhang ◽  
Che Ting Chan
Keyword(s):  
Wave Propagation ◽  
Electromagnetic Waves ◽  
Anderson Localization ◽  
Random Media ◽  
Normal Incidence ◽  
Disordered Media ◽  
One Dimensional ◽  
Gain Loss ◽  
The Waves ◽  
Localization Behavior

AbstractIt has been shown recently that the backscattering of wave propagation in one-dimensional disordered media can be entirely suppressed for normal incidence by adding sample-specific gain and loss components to the medium. Here, we study the Anderson localization behaviors of electromagnetic waves in such gain-loss balanced random non-Hermitian systems when the waves are obliquely incident on the random media. We also study the case of normal incidence when the sample-specific gain-loss profile is slightly altered so that the Anderson localization occurs. Our results show that the Anderson localization in the non-Hermitian system behaves differently from random Hermitian systems in which the backscattering is suppressed.

scholarly journals SWRT: A package for semi-analytical solutions of surface wave propagation, including mode conversion, across transversely aligned vertical discontinuities

2018 ◽  
Vol 7 (1) ◽  
pp. 101-112 ◽  
Author(s):  
Arjun Datta
Keyword(s):  
Wave Propagation ◽  
Surface Wave ◽  
Mode Conversion ◽  
Normal Incidence ◽  
Seismic Wave Propagation ◽  
Reflection And Transmission ◽  
Computing Power ◽  
Transmission Coefficients ◽  
Surface Wave Propagation ◽  
Core Functionality

Abstract. We present a suite of programs that implement decades-old algorithms for computation of seismic surface wave reflection and transmission coefficients at a welded contact between two laterally homogeneous quarter-spaces. For Love as well as Rayleigh waves, the algorithms are shown to be capable of modelling multiple mode conversions at a lateral discontinuity, which was not shown in the original publications or in the subsequent literature. Only normal incidence at a lateral boundary is considered so there is no Love–Rayleigh coupling, but incidence of any mode and coupling to any (other) mode can be handled. The code is written in Python and makes use of SciPy's Simpson's rule integrator and NumPy's linear algebra solver for its core functionality. Transmission-side results from this code are found to be in good agreement with those from finite-difference simulations. In today's research environment of extensive computing power, the coded algorithms are arguably redundant but SWRT can be used as a valuable testing tool for the ever evolving numerical solvers of seismic wave propagation. SWRT is available via GitHub (https://github.com/arjundatta23/SWRT.git).

scholarly journals SWRT: A package for semi-analytical solutions of surface wave propagation, including mode conversion, across transversely aligned vertical discontinuities

2017 ◽  
Author(s):  
Arjun Datta
Keyword(s):  
Wave Propagation ◽  
Surface Wave ◽  
Mode Conversion ◽  
Normal Incidence ◽  
Seismic Wave Propagation ◽  
Reflection And Transmission ◽  
Computing Power ◽  
Transmission Coefficients ◽  
Surface Wave Propagation ◽  
Core Functionality

Abstract. We present a suite of programs that implement decades-old algorithms for computation of seismic surface wave reflection and transmission coefficients at a welded contact between two laterally homogeneous quarter-spaces. For Love as well as Rayleigh waves, the algorithms are shown to be capable of modelling multiple mode conversions at a lateral discontinuity, which was not shown in the original publications or in the subsequent literature. Only normal incidence at a lateral boundary is considered so there is no Love-Rayleigh coupling, but incidence of any mode and coupling to any (other) mode can be handled. The code is written in Python and makes use of SciPy's Simpson's rule integrator and NumPy's linear algebra solver for its core functionality. Transmission side results from this code are found to be in good agreement with those from finite difference simulations. In today's research environment of extensive computing power, the coded algorithms are arguably redundant but SWRT can be used as a valuable testing tool for the ever evolving numerical solvers of seismic wave propagation. SWRT is available via GitHub (https://github.com/arjundatta23/sw_reftrans.git).

SOME ASPECTS OF ELASTIC WAVE PROPAGATION IN FLUID‐SATURATED POROUS SOLIDS

Geophysics ◽  
1961 ◽  
Vol 26 (2) ◽  
pp. 169-181 ◽  
Author(s):  
J. Geertsma ◽  
D. C. Smit
Keyword(s):  
Wave Propagation ◽  
Low Frequency ◽  
Normal Incidence ◽  
Approximate Solutions ◽  
Porous Solids ◽  
Geophysical Research ◽  
Weak Points ◽  
Biot’S Equations ◽  
Second Wave ◽  
The Waves

Biot’s equations for the propagation of dilatational waves in fluid‐saturated porous solids in the low‐frequency range are analyzed for the purpose of application in geophysical research. The deformation constants of the system are unraveled in terms of compressibilities and porosity, and suitable approximate solutions for wave velocity and attenuation of the waves of both the first and the second kind are obtained. A saturated elastic porous solid is found to behave, as far as the wave of the first kind is concerned, approximately as a standard element. The wave of the second kind rapidly dies out with increasing distance from the source and consequently one might infer that in seismic studies only the wave of the first kind needs consideration. It is shown, however, that its presence has an effect upon the reflection and absorption at any interface between two different fluid‐saturated porous solids. At such an interface a wave of the second kind is again generated. General formulae for the reflection and absorption for normal incidence at the interface are obtained, which include the effect of second‐wave generation. Additional results of the investigation are the following: A rather simple formula for the speed of sound in sedimentary rocks (the wave of the first kind) is obtained, which has to replace the so‐called “time‐average relation” now sometimes used. A comparison between the results obtained here and published results on wave propagation in simpler fluid‐solid systems, such as, for instance, suspensions, showed some weak points in the older theories. Suggestions for possible improvements are given.

scholarly journals Effect of the Parametric Variations of Semiconductor Screen on Line Parameters and Wave Properties of Underground Cable

2019 ◽  
Vol 8 (4) ◽  
pp. 5279-5287
Keyword(s):  
Wave Propagation ◽  
High Frequency ◽  
Electromagnetic Properties ◽  
Propagation Mechanism ◽  
Loop Current ◽  
Cable Structure ◽  
Underground Cable ◽  
Wide Range ◽  
On Line ◽  
Wave Properties

Detection and understanding of different high frequency phenomenon in multilayered underground (UG) cable require a thorough study of wave propagation mechanism which is governed by the line parameters of the cable. Line parameters are the functions of cable geometric and electromagnetic properties. Therefore the inclusion of semiconducting screen in cable structure influences the line parameters as well as wave properties of the cable. This paper aims to investigate the effects of the variation of different geometric and electrical properties of the semiconducting screen on line parameters as well as wave propagation characteristics of UG cable over a wide range of frequency. The complete impedance matrix of cable considering the effect of the semiconducting screen is derived using loop current analysis without invoking the theory of a double-layered conductor system. A comparative analysis on the effect of parametric variations of the semiconducting screen on line parameters as well as wave properties between the cable with and without semiconducting screen over a wide range of frequency is performed. This analysis indicates that the wave properties like attenuation or phase velocity are considerably influenced by inclusions of the semiconducting screen in cable structure, especially at high frequency.

scholarly journals Analysis of surface acoustic wave properties in CaYAl3O7 single crystal

2021 ◽  
Vol 2131 (5) ◽  
pp. 052099
Author(s):  
R M Taziev
Keyword(s):  
Wave Propagation ◽  
Acoustic Wave ◽  
Single Crystal ◽  
Surface Acoustic Wave ◽  
Coupling Coefficient ◽  
Propagation Direction ◽  
Tetragonal Symmetry ◽  
Flow Angle ◽  
Wave Propagation Direction ◽  
Wave Properties

Abstract The success on the growth of new piezoelectric materials allows sufficiently increase the operating temperature of the surface acoustic wave (SAW) devices from 300°C to 1000°C. A new calcium yttrium aluminate (CaYAl3O7) single crystal of the tetragonal symmetry has piezoelectric properties up to the temperature of 1000°C. The paper presents a numerical study of the surface acoustic wave properties in the crystal. The SAW velocity, electromechanical coupling coefficient and power flow angle are studied for different crystal cuts of CaYAl3O7. It is shown that the maximum value of SAW coupling coefficient (0.24%) is on the Z+60°-cut and wave propagation direction along the X-axis of the crystal. For the Z-cut and wave propagation direction along the X+45°-axis of crystal, the SAW coupling coefficient is equal to 0.2%. These two cuts of the crystal are potentially useful for SAW device applications.

scholarly journals EVALUATION OF A PARAMETRIC-TYPE WAVE TRANSFORMATION MODEL AGAINST FIELD AND LABORATORY DATA

2012 ◽  
Vol 1 (33) ◽  
pp. 51
Author(s):  
Alireza Jafari ◽  
Nick Cartwright
Keyword(s):  
Wave Propagation ◽  
Laboratory Data ◽  
Break Point ◽  
Coastal Engineering ◽  
Transformation Model ◽  
Wave Transformation ◽  
Additional Energy ◽  
Propagation Models ◽  
Dissipation Model ◽  
Wave Properties

Predicting wave properties via parametric wave propagation models are broadly used in many coastal engineering applications. Numerous researchers have refined these types of models to increase their accuracy including; Battjes and Janssen (1978), Thornton and Guza (1983), Baldock et al. (1998), and Alsina and Baldock (2007). Alsina and Baldock (2007), proposed an improved parametric wave propagation models for a non-saturated surfzone which returns relatively more accuracy in comparison to others. In this paper, the Alsina and Baldock (2007) model along with Baldock et al. (1998) and Thornton and Guza (1983), are applied to data collected in South-East Queensland under stormy and calm conditions as well as laboratory data. Some of the comparisons indicate the need to incorporate some additional energy loss at the break point to account for plunging type breakers where the existing bore dissipation model is insufficient.

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