scholarly journals ABOUT THE ACCELERATION RATE OF RELATIVISTIC BEAMS BY A SURFACE WAVE IN A DIELECTRIC LASER ACCELERATOR

2021 ◽  
pp. 57-60
Author(s):  
O.O. Bolshov ◽  
A.V. Vasiliev ◽  
A.I. Povrozin ◽  
G.V. Sotnikov
Keyword(s):  
Surface Wave ◽  
Phase Velocity ◽  
Refractive Indices ◽  
Dielectric Media ◽  
At Resonance ◽  
Acceleration Rate ◽  
Excited Wave ◽  
Optically Transparent ◽  
Relativistic Particles ◽  
Resonance Acceleration

An analysis of the dependence of the acceleration rate of charged particles by a surface wave arising when a la-ser pulse/(plane wave) is incident on the interface between two dielectric media on the phase velocity of the excited wave is carried out. It is shown that at resonance acceleration this dependence has a maximum, for ultra-relativistic particles the acceleration rate tends to zero. The dependences of the acceleration rate on the phase velocity of the excited wave for various refractive indices (dielectric permittivities) of optically transparent medias are investigated analytically and numerically.

scholarly journals Sensitivities of surface wave velocities to the medium parameters in a radially anisotropic spherical Earth and inversion strategies

2015 ◽  
Vol 58 (5) ◽  
Author(s):  
Sankar N. Bhattacharya
Keyword(s):  
Surface Wave ◽  
Phase Velocity ◽  
Group Velocity ◽  
Wave Velocity ◽  
Love Waves ◽  
P Wave ◽  
Model Parameters ◽  
Nonlinear Inversion ◽  
Wave Velocities ◽  
Spherical Earth

<p>Sensitivity kernels or partial derivatives of phase velocity (<em>c</em>) and group velocity (<em>U</em>) with respect to medium parameters are useful to interpret a given set of observed surface wave velocity data. In addition to phase velocities, group velocities are also being observed to find the radial anisotropy of the crust and mantle. However, sensitivities of group velocity for a radially anisotropic Earth have rarely been studied. Here we show sensitivities of group velocity along with those of phase velocity to the medium parameters <em>V<sub>SV</sub>, V<sub>SH </sub>, V<sub>PV</sub>, V<sub>PH , </sub></em><em>h</em><em> </em>and density in a radially anisotropic spherical Earth. The peak sensitivities for <em>U</em> are generally twice of those for <em>c</em>; thus <em>U</em> is more efficient than <em>c</em> to explore anisotropic nature of the medium. Love waves mainly depends on <em>V<sub>SH</sub></em> while Rayleigh waves is nearly independent of <em>V<sub>SH</sub></em> . The sensitivities show that there are trade-offs among these parameters during inversion and there is a need to reduce the number of parameters to be evaluated independently. It is suggested to use a nonlinear inversion jointly for Rayleigh and Love waves; in such a nonlinear inversion best solutions are obtained among the model parameters within prescribed limits for each parameter. We first choose <em>V<sub>SH</sub></em>, <em>V<sub>SV </sub></em>and <em>V<sub>PH</sub></em> within their corresponding limits; <em>V<sub>PV</sub></em> and <em>h</em> can be evaluated from empirical relations among the parameters. The density has small effect on surface wave velocities and it can be considered from other studies or from empirical relation of density to average P-wave velocity.</p>

SURFACE-WAVE PROPAGATION OVER PLANE-LAYERED DIELECTRICS

1963 ◽  
Vol 41 (2) ◽  
pp. 405-413
Author(s):  
D. Morris
Keyword(s):  
Surface Wave ◽  
Phase Velocity ◽  
Experimental Investigations ◽  
Total Field ◽  
Power Variation ◽  
Surface Wave Propagation ◽  
Dielectric System ◽  
Layered Dielectrics ◽  
Layered Dielectric ◽  
The Waves

A two-layer dielectric system, consisting of a thin polystyrene sheet on top of water, is examined as a possible guiding structure for surface waves. Experimental investigations, at a frequency of 9.35 Gc/sec, of the phase velocity of the waves close to the surface of the upper layer, and the power variation with height above it, are described. A slow wave was found to propagate near the surface and its phase velocity was found to agree with that predicted theoretically for a TM surface wave. Qualitative agreement between the experimental and theoretical power variation with height confirmed the existence of a surface-wave contribution to the total field above such a layered dielectric system.

Ground roll: A potential tool for constraining shallow shear‐wave structure

Geophysics ◽  
1993 ◽  
Vol 58 (5) ◽  
pp. 713-719 ◽  
Author(s):  
Ghassan I. Al‐Eqabi ◽  
Robert B. Herrmann
Keyword(s):  
Surface Wave ◽  
Phase Velocity ◽  
Wave Velocity ◽  
Wave Structure ◽  
S Wave ◽  
Data Set ◽  
Velocity Inversion ◽  
Ground Roll ◽  
Lateral Variations ◽  
Wave Arrival

The objective of this study is to demonstrate that a laterally varying shallow S‐wave structure, derived from the dispersion of the ground roll, can explain observed lateral variations in the direct S‐wave arrival. The data set consists of multichannel seismic refraction data from a USGS-GSC survey in the state of Maine and the province of Quebec. These data exhibit significant lateral changes in the moveout of the ground‐roll as well as the S‐wave first arrivals. A sequence of surface‐wave processing steps are used to obtain a final laterally varying S‐wave velocity model. These steps include visual examination of the data, stacking, waveform inversion of selected traces, phase velocity adjustment by crosscorrelation, and phase velocity inversion. These models are used to predict the S‐wave first arrivals by using two‐dimensional (2D) ray tracing techniques. Observed and calculated S‐wave arrivals match well over 30 km long data paths, where lateral variations in the S‐wave velocity in the upper 1–2 km are as much as ±8 percent. The modeled correlation between the lateral variations in the ground‐roll and S‐wave arrival demonstrates that a laterally varying structure can be constrained by using surface‐wave data. The application of this technique to data from shorter spreads and shallower depths is discussed.

Surface-Wave Tomography of Eastern and Central Tibet from Two-Plane-Wave Inversion: Rayleigh-Wave and Love-Wave Phase Velocity Maps

2020 ◽  
Vol 110 (3) ◽  
pp. 1359-1371
Author(s):  
Lun Li ◽  
Yuanyuan V. Fu
Keyword(s):  
Surface Wave ◽  
Tibetan Plateau ◽  
Phase Velocity ◽  
Rayleigh Wave ◽  
Love Wave ◽  
The Tibetan Plateau ◽  
Surface Wave Tomography ◽  
Wave Phase ◽  
Wave Phase Velocity ◽  
Wave Tomography

ABSTRACT An understanding of mantle dynamics occurring beneath the Tibetan plateau requires a detailed image of its seismic velocity and anisotropic structure. Surface waves at long periods (&gt;50  s) could provide such critical information. Though Rayleigh-wave phase velocity maps have been constructed in the Tibetan regions using ambient-noise tomography (ANT) and regional earthquake surface-wave tomography, Love-wave phase velocity maps, especially those at longer periods (&gt;50  s), are rare. In this study, two-plane-wave teleseismic surface-wave tomography is applied to develop 2D Rayleigh-wave and Love-wave phase velocity maps at periods between 20 and 143 s across eastern and central Tibet and its surroundings using four temporary broadband seismic experiments. These phase velocity maps share similar patterns and show high consistency with those previously obtained from ANT at overlapping periods (20–50 s), whereas our phase velocity maps carry useful information at longer periods (50–143 s). Prominent slow velocity is imaged at periods of 20–143 s beneath the interior of the Tibetan plateau (i.e., the Songpan–Ganzi terrane, the Qiangtang terrane, and the Lhasa terrane), implying the existence of thick Tibetan crust along with warm and weak Tibetan lithosphere. In contrast, the dispersal of fast velocity anomalies coincides with mechanically strong, cold tectonic blocks, such as the Sichuan basin and the Qaidam basin. These phase velocity maps could be used to construct 3D shear-wave velocity and radial seismic anisotropy models of the crust and upper mantle down to 250 km across the eastern and central Tibetan plateau.

scholarly journals Surface Wave Tomography of the Alps Using Ambient-Noise and Earthquake Phase Velocity Measurements

2018 ◽  
Vol 123 (2) ◽  
pp. 1770-1792 ◽  
Author(s):  
Emanuel D. Kästle ◽  
A. El-Sharkawy ◽  
L. Boschi ◽  
T. Meier ◽  
C. Rosenberg ◽  
...  
Keyword(s):  
Surface Wave ◽  
Phase Velocity ◽  
Ambient Noise ◽  
Surface Wave Tomography ◽  
Velocity Measurements ◽  
Wave Tomography ◽  
The Alps
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