Acoustic Shock Waves Research Articles

Nonextensive dust acoustic solitary and shock waves in nonplanar geometry

The properties of cylindrical and spherical dust acoustic (DA) solitary and shock waves in an unmagnetized electron depleted dusty plasma consisting of inertial dust fluid and ions featuring Tsallis statistics are investigated by employing the reductive perturbation technique. A Korteweg-de Vries Burgers (KdVB) equation is derived and its numerical solution is obtained. The effects of ion nonextensivity and dust kinematic viscosity on the basic features of DA solitary and shock waves are discussed in nonplanar geometry. It is found that nonextensive nonplanar DA waves behave quite differently from their one-dimensional planar counterpart.

Ion acoustic solitary and shock waves with nonextensive electrons and thermal positrons in nonplanar geometry

The nonlinear wave structures of ion acoustic waves (IAWs) in an unmagnetized plasma consisting of nonextensive electrons and thermal positrons are studied in bounded nonplanar geometry. Using reductive perturbation technique we have derived cylindrical and spherical Korteweg-de Vries-Burgers’ (KdVB) equations for IAWs. The presence of nonextensive q-distributed electrons is shown to influence the solitary and shock waves. Furthermore, in the existence of ion kinematic viscosity, the shock wave structure appears. Also, the effects of nonextensivity of electrons, ion kinematic viscosities, positron concentration on the properties of ion acoustic shock waves (IASWs) are discussed in nonplanar geometry. It is found that both compressive and rarefactive type solitons or shock waves are obtained depending on the plasma parameter.

Nonlinear Propagation of Ion-Acoustic Shock Waves in Dissipative Electron–Positron–Ion Plasma with Trapped Electrons and Relativistic Ions

Ion acoustic shock waves are studied in dissipative three-component plasma. Relativistic ions, Maxwell–Boltzmann distributed positrons, nonisothermal electrons are considered in the plasma and we also consider the kinematic viscosity among the plasma constituents. The dynamics of the nonlinear wave are governed by a modified Korteweg–de Vries Burger equation that possesses dissipative Burger term. The trapping parameter (β), the ratio of the free electron temperature to the trapped electron temperature, is treated as a variable. The effects of the coefficient of the kinematic viscosity, parameter β and also relativistic factor on the solitary and shock waves are studied.

The characteristics of ion acoustic shock waves in non-Maxwellian plasmas with (G′/G)-expansion method

Korteweg-de-Vries-Burger (K-dVB) equation is derived for ion acoustic shock waves in electron-positron-ion plasmas. Electrons and positrons are considered superthermal and are effectively modeled by a kappa distribution in which ions are as cold fluid. The analytical traveling wave solutions of the K-dVB equation investigated, through the (G′/G)-expansion method. These traveling wave solutions are expressed by hyperbolic function, trigonometric functions are rational functions. When the parameters are taken special values, the shock waves are derived from the traveling waves. It is observed that the amplitude ion acoustic shock waves increase as spectral index κ and kinematic viscosity ηi,0 increases in which with increasing positron density β and electron temperature σ the shock amplitude decreases. Also, numerically the effect different parameters on the nonlinearity A and dispersive B terms and wave velocity V investigated.

Placement of the dam for the no. 2 kambaratinskaya HPP by large-scale blasting: some observations

Results of complex instrument observations of large-scale blasting during construction of the dam for the No. 2 Kambaratinskaya HPP on the Naryn River in the Republic of Kirgizia are analyzed. The purpose of these observations was: to determine the actual parameters of the seismic process, evaluate the effect of air and acoustic shock waves, and investigate the kinematics of the surface formed by the blast in its core region within the mass of fractured rocks.

Dust acoustic shock waves in two temperatures charged dusty grains

The reductive perturbation method has been used to derive the Korteweg–de Vries–Burger equation and modified Korteweg–de Vries–Burger for dust acoustic shock waves in a homogeneous unmagnetized plasma having electrons, singly charged ions, hot and cold dust species with Boltzmann distributions for electrons and ions in the presence of the cold (hot) dust viscosity coefficients. The behavior of the shock waves in the dusty plasma has been investigated.

Linear and nonlinear excitations in complex plasmas with nonadiabatic dust charge fluctuation and dust size distribution

Both linear and nonlinear excitation in dusty plasmas have been investigated including the nonadiabatic dust charge fluctuation and Gaussian size distribution dust particles. A linear dispersion relation and a Korteweg—de Vries—Burgers equation governing the dust acoustic shock waves are obtained. The relevance of the instability of wave and the wave evolution to the dust size distribution and nonadiabatic dust charge fluctuation is illustrated both analytically and numerically. The numerical results show that the Gaussian size distribution of dust particles and the nonadiabatic dust charge fluctuation have strong common influence on the propagation of both linear and nonlinear excitations.

First ionospheric images of the seismic fault slip on the example of the Tohoku-oki earthquake

[1] 1Hz GPS measurements from the Japanese GPS network GEONET allowed to retrieve information on the seismic fault of the great M9.0 Tohoku-oki earthquake from the ionosphere total electron content (TEC) measurements. The first arrival of the TEC perturbation was registered 464 seconds after the earthquake ∼140 km on the east from the epicenter. Within next 45 seconds the distribution of ionospheric points imaged a rectangular area (37.39 - 39.28°N; 142.8 – 143.73°E), which coincides with the area of the coseismic crustal uplift. From this source region, the coseismic ionospheric perturbation further propagated at 1.3-1.5 km/s. Such velocity values are 30-40% higher than previously reported for acoustic waves. It is likely that we observed shock-acoustic waves propagating at supersonic speed and having blown all the electrons available between the ground and the height of detection. This fact is coherent with registration of the first arrival of perturbation 464 sec after the earthquake that is, generally speaking, too short time for a regular acoustic wave to reach the ionosphere. Our findings show that the real-time GPS monitoring of seismo-active areas could inform about the parameters of coseismic crustal displacements and can be, subsequently, used for short-term tsunami warnings. In the case of the 03/11/2011 earthquake, the first ionosphere perturbations were registered ∼17 minutes before the tsunami arrived on the east coast of Honshu.

Effect of q-nonextensive distribution of electrons on dust acoustic shock waves in strongly coupled dusty plasmas

The reductive perturbation method is used to derive the Kordeweg – de Vries – Burgers equation in strongly coupled dusty plasmas containing Boltzmann distributed ions and q-nonextensive electrons. It is observed that the nonlinear propagation of the dust acoustic waves gives rise to shock structures when there is strong correlation among the dust grains. The effect of the q-nonextensive parameter on the shock waves is discussed.

Quantum ion–acoustic shock waves in warm dissipative electron–positron–ion plasmas with relativistic ions

Propagation of nonlinear quantum ion–acoustic shock waves in dense quantum plasma, whose constituents are electrons, positrons, and positive ions, is investigated using a quantum hydrodynamical model. Moreover, it is assumed that ion velocity is weakly relativistic. Also, we consider the effects of kinematic viscosity among the plasma constituents. By using reductive perturbation method, the Korteweg – de Vries – Burger equation is derived. The effects of relativistic ions, ion temperature, and the quantum Bohm potential on the shock waves are reported in this paper.

Dust acoustic shock waves in coupled dusty plasmas with nonthermal ions

Dust acoustic shock waves of the Korteweg-de Vries–Burgers (KdV–Burgers) equation and the modified Korteweg-de Vries–Burgers (MKdV–Burgers) equation are studied in strongly coupled dusty plasmas containing nonthermal ions and Boltzmann-distributed electrons. The effects of important parameters, such as nonthermal parameter, relative temperature, relative density and dust particles viscosity, on the properties of shock waves are discussed.

Acoustic shock wave propagation in a heterogeneous medium: A numerical simulation beyond the parabolic approximation

Numerical simulation of nonlinear acoustics and shock waves in a weakly heterogeneous and lossless medium is considered. The wave equation is formulated so as to separate homogeneous diffraction, heterogeneous effects, and nonlinearities. A numerical method called heterogeneous one-way approximation for resolution of diffraction (HOWARD) is developed, that solves the homogeneous part of the equation in the spectral domain (both in time and space) through a one-way approximation neglecting backscattering. A second-order parabolic approximation is performed but only on the small, heterogeneous part. So the resulting equation is more precise than the usual standard or wide-angle parabolic approximation. It has the same dispersion equation as the exact wave equation for all forward propagating waves, including evanescent waves. Finally, nonlinear terms are treated through an analytical, shock-fitting method. Several validation tests are performed through comparisons with analytical solutions in the linear case and outputs of the standard or wide-angle parabolic approximation in the nonlinear case. Numerical convergence tests and physical analysis are finally performed in the fully heterogeneous and nonlinear case of shock wave focusing through an acoustical lens.

Ion acoustic shock waves in degenerate plasmas

Korteweg de Vries Burgers equation for negative ion degenerate dissipative plasma has been derived using reductive perturbation technique. The quantum hydrodynamic model is used to study the quantum ion acoustic shock waves. The effects of different parameters on quantum ion acoustic shock waves are studied. It is found that quantum parameter, electrons Fermi temperature, temperature of positive and negative ions, mass ratio of positive to negative ions, viscosity, and density ratio have significant impact on the shock wave structure in negative ion degenerate plasma.

Effect of nonthermal electrons on the propagation characteristics and stability of two-dimensional nonlinear electrostatic coherent structures in relativistic electron positron ion plasmas

Two-dimensional propagation of nonlinear ion acoustic shock and solitary waves in an unmagnetized plasma consisting of nonthermal electrons, Boltzmannian positrons, and singly charged hot ions streaming with relativistic velocities are investigated. The system of fluid equations is reduced to Kadomtsev-Petviashvili-Burgers and Kadomtsev-Petviashvili (KP) equations in the limit of small amplitude perturbation. The dependence of the ion acoustic shock and solitary waves on various plasma parameters are explored in detail. Interestingly, it is observed that increasing the nonthermal electron population increases the wave dispersion which enervates the strength of the ion acoustic shock wave; however, the same effect leads to an enhancement of the soliton amplitude due to the absence of dissipation in the KP equation. The present investigation may be useful to understand the two-dimensional propagation characteristics of small but finite amplitude localized shock and solitary structures in planetary magnetospheres and auroral plasmas where nonthermal populations of electrons have been observed by several satellite missions.

Effect of q-nonextensive distribution of electrons on ion acoustic shock waves in dissipative plasma

Ion acoustic shock waves (IASWs) are studied in a plasma consisting of nonextensive electrons and ions. The dissipation is taken into account the kinematic viscosity among the plasma constituents. The Korteweg-de Vries-Burgers (KdV-Burgers) equation is derived by reductive perturbation method. Shock waves are solutions of KdV-Burgers equation. It is shown that acceptable values of q-parameter (where q stands for the electron nonextensive parameter) are more than 3 in a weakly nonlinear analysis. We have found that the amplitude of shock waves decreases by an increasing q-parameter.

Effects of adiabaticity and non-adiabaticity of dust charge fluctuation on the propagation of the dust ion acoustic waves in inhomogeneous dusty plasma

A theoretical investigation has been made for adiabatic positive and negative dust charge fluctuations on the propagation of dust-ion acoustic waves (DIAWs) in a weakly inhomogeneous, collisionless, unmagnetized dusty plasmas consisting of cold positive ions, stationary positively and negatively charged dust particles and isothermal electrons. The reductive perturbation method is employed to reduce the basic set of fluid equations to the variable coefficients Korteweg–de Vries (KdV) equation. Either compressive or rarefactive solitons are shown to exist depending on the critical value of the ion density, which in turn, depends on the inhomogeneous distribution of the ion. The dissipative effects of non-adiabatic dust charge variation has been studied which cause generation of dust ion acoustic shock waves governed by KdV-Burger (KdVB) equation. The results of the present investigation may be applicable to some dusty plasma environments, such as dusty plasma existing in polar mesosphere region.

Cavitation inception and damage effects in liquid mercury exposed to a high-energy pulsed proton beam.

The Oak Ridge National Laboratory Spallation Neutron Source (SNS) employs a high-energy proton beam incident on a liquid mercury target to generate short bursts of neutrons. Concomitant with neutron production is the rapid heating of the mercury, resulting in the formation of acoustic shock waves and the nucleation of cavitation bubbles. The subsequent collapse of these bubbles may result in the premature erosion of the target’s steel walls. We report on a multi-pronged effort to both understand and address the problem by (1) inhibiting cavitation inception using bubble injection, (2) analyze cavitation and cavitation cloud dynamics using passive noise diagnostics, and (3) mitigating vessel wall damage using surface modification techniques. [Work supported by the ORNL Spallation Neutron Source, which is managed by UT-Battelle, LLC, under Contract No. DE-AC05-00OR22725 for the U.S. Department of Energy.]

The 3+1 dimensional Kadomtsev–Petviashvili Burgers' equation in non-uniform dusty plasmas

Using the perturbation method, the 3+1 dimensional modified variable coefficient Kadomtsev–Petviashvili (MKP) Burgers' equation governing nonlinear dust acoustic shock waves is derived with the combined effects of non-adiabatic dust charge fluctuation, higher-order transverse perturbation and the non-thermally distributed ions in inhomogeneous dusty plasmas due to spatial gradients of dust charge and plasma densities for the first time. The MKP Burgers' equation is reduced to the standard variable coefficient Kadomtsev–Petviashvili (KP) Burgers' equation. A particular solution of this KP Burgers' equation is also obtained. It is shown that the dust acoustic shock waves can exist in the KP Burgers' equation.

Scattering of ultrasonic shock waves in suspensions of silica nanoparticles

Experiments are carried out to assess, for the first time, the validity of a generalized Burgers' equation, introduced first by Davidson [J. Acoust. Soc. Am. 54, 1331-1342 (1973)] to compute the nonlinear propagation of finite amplitude acoustical waves in suspensions of "rigid" particles. Silica nanoparticles of two sizes (33 and 69 nm) have been synthesized in a water-ethanol mixture and precisely characterized via electron microscopy. An acoustical beam of high amplitude is generated at 1 MHz inside a water tank, leading to the formation of acoustical shock waves through nonlinear steepening. The signal is then measured after propagation in a cylinder containing either a reference solution or suspensions of nanoparticles. In this way, a "nonlinear attenuation" is obtained and compared to the numerical solution of a generalized Burgers' equation adapted to the case of hydrosols. An excellent agreement (corresponding to an error on the particles size estimation of 3 nm) is achieved in the frequency range from 1 to 40 MHz. Both visco-inertial and thermal scattering are significant in the present case, whereas thermal effects can generally be neglected for most hydrosols. This is due to the value of the specific heat ratio of water-ethanol mixture which significantly differs from unity.

Dust acoustic shock waves in plasmas with strongly coupled dusts and superthermal ions

The reductive perturbation method is used for deriving the Kordeweg–de Vries–Burgers (KdVB) equation in strongly coupled dusty plasmas, containing Boltzmann distributed electron and superthermal ions. We discuss the shock wave solutions and also study the effect of superthermal ions on the waves.