Acoustic Shock Waves Research Articles

Characteristics of nonlinear dust acoustic waves in a Lorentzian dusty plasma with effect of adiabatic and nonadiabatic grain charge fluctuation

In this paper, characteristics of small amplitude nonlinear dust acoustic wave have been investigated in a unmagnetized, collisionless, Lorentzian dusty plasma where electrons and ions are inertialess and modeled by generalized Lorentzian Kappa distribution. Dust grains are inertial and equilibrium dust charge is negative. Both adiabatic and nonadiabatic fluctuation of charges on dust grains have been taken under consideration. For adiabatic dust charge variation reductive perturbation analysis gives rise to a KdV equation that governs the nonlinear propagation of dust acoustic waves having soliton solutions. For nonadiabatic dust charge variation nonlinear propagation of dust acoustic wave obeys KdV-Burger equation and gives rise to dust acoustic shock waves. Numerical estimation for adiabatic grain charge variation shows the existence of rarefied soliton whose amplitude and width varies with grain charges. Amplitude and width of the soliton have been plotted for different electron Kappa indices keeping ion velocity distribution Maxwellian. For non adiabatic dust charge variation, ratio of the coefficients of Burger term and dispersion term have been plotted against charge fluctuation for different kappa indices. All these results approach to the results of Maxwellian plasma if both electron and ion kappa tends to infinity.

Ion acoustic shock and periodic waves through Burgers equation in weakly and highly relativistic plasmas with nonextensivity

A comparative study is carried out for the nonlinear propagation of ion acoustic shock waves both for the weakly and highly relativistic plasmas consisting of relativistic ions and q-distributed electrons and positions. The Burgers equation is derived to reveal the physical phenomena using the well known reductive perturbation technique. The integration of the Burgers equation is performed by the method. The effects of positron concentration, ion–electron temperature ratio, electron–positron temperature ratio, ion viscosity coefficient, relativistic streaming factor and the strength of the electron and positron nonextensivity on the nonlinear propagation of ion acoustic shock and periodic waves are presented graphically and the relevant physical explanations are provided.

Dust ion acoustic solitary and shock waves in strongly coupled dusty plasma in presence of attractive interparticle interaction potential

The streaming of ions through the dust particles significantly modifies the repulsive Debye-Hückel type of interaction in the sheath and pre-sheath regions and leads to the appearance of oscillatory and attractive wake type interaction. In this paper, we investigate the formation of dust-ion acoustic solitary and shock waves in the presence of streaming ions in a strongly coupled dusty plasma. The generalized hydrodynamic equation is used to describe the dust dynamics, and the dust-dust interaction has been taken into account via the electrostatic pressure term. The novel feature of the present study is the incorporation of both the repulsive and attractive interactions in the electrostatic pressure term. The flow of ions along the vertical direction in the sheath/presheath region of the plasma brings asymmetry to the dust dynamics, which has been carefully handled while considering the effect of strong coupling in the formation of nonlinear structures in such plasma. The study reveals that the ion streaming velocity has a crucial role in controlling the nonlinear coherent structures.

Ionospheric detection and localization of volcano eruptions on the example of the April 2015 Calbuco events

AbstractUsing data from ground‐based Global Navigation Satellite Systems (GNSS) receivers located in southern Chile, we study the ionospheric total electron content (TEC) response to two eruptions of the Calbuco volcano that occurred on 22–23 April 2015. In both cases, the TEC response showed quasi‐periodic signals with several consecutive wave trains. The averaged amplitude of the observed covolcanic TEC perturbations amounted 0.45 total electron content unit, 1 TECU = 1016 el m−2 (TECU) for the first eruption and 0.16 TECU for the second one. We compare amplitudes of the TEC response to volcano eruptions of different intensity from our and previously published data, and we show that both the intensity and the background ionospheric conditions define the amplitude of ionospheric covolcanic disturbances. The relative contribution, however, scales with the eruption intensity. The traveltime diagrams allowed to estimate the propagation speed of the observed covolcanic TEC perturbations as ~900–1200 m/s, which is close to the acoustic (or shock acoustic) waves speed at the ionospheric height. The spectrograms are consistent with the conclusion on the acoustic nature of the observed TEC perturbations. Finally, we use the approximation of a spherical wave propagating at a constant velocity from a point source, and for the first time, we calculate the location of the volcanic source and the onset time of the volcano eruption from ionospheric measurements. We show that even from 30 s ionospheric GPS data it is possible to “localize” the eruptive source within several degrees of latitude/longitude.

On the coseismic ionospheric disturbances after the Nepal Mw7.8 earthquake on April 25, 2015 using GNSS observations

Nepal Mw7.8 earthquake occurred at 06:11:26 UTC on April 25, 2015. The epicenter was located at 28.147°N, 84.708°E, with the focal depth of 15km. In this paper, the coseismic ionospheric disturbances were analyzed using Vertical Total Electron Content from Global Navigation Satellite System (GNSS) observations obtained from 309 continuous tracking stations around the epicenter. The results show that significant ionospheric disturbances occurred within 10min after the earthquake. The maximum anomaly reached 1.34 TECU; the maximum duration was 10min; the farthest anomaly was found beyond 3000km from the epicenter. The ionospheric response was attributed to two modes: shock acoustic waves and Rayleigh wave. Within 500km from the epicenter, ionosphere anomaly was induced by both waves, with average propagating speed of 0.61 and 1.62km/s, respectively. With increasing epicentral distance, the ionospheric disturbances caused by acoustic waves gradually weakened, whereas Rayleigh waves induced ionosphere disturbances reached up to 3000km from the epicenter. The propagation speed of Rayleigh waves gradually increased to 2.74km/s while the distance from the epicenter to sub-ionospheric point was over 1500km. The occurrence of the disturbances appeared strong directivity. The amplitudes of the disturbances were large to the south of the epicenter. In contrast, to the northwest of the epicenter, few disturbances were observed, and the amplitudes of these disturbances were small. In general, the amplitude of the anomaly decreased with increasing epicentral distance. However, the amplitude of the anomaly increased at 1500–2500km to the northeast of the epicenter.

Radiation linear energy transfer and drop size dependence of the low frequency signal from tiny superheated droplets

The bubble nucleation in superheated tiny droplets of R-12 (CCl2F2, boiling point: −29.8°C) induced by neutrons and α-particles has been observed using condenser microphone as an acoustic sensor. The superheated droplets used in these experiments are of very small radii having distribution with main peak around 2–3µm expanding until about 40µm. The low frequency component of the acoustic shock wave released during bubble nucleation has been measured with condenser microphone and the analysis has been done using ROOT software. Pulses due to bubble nucleation have been recorded in the presence of 241Am–Be neutron source (few keV to about 10MeV) and 241Am alpha-source (5.48MeV with intensity 85.2%). The observables related to the power associated with bubble nucleation (P) and the area under the frequency spectrum of the signal (PFreq) have been estimated for the α-particle and neutron induced events. It shows that the α-particle induced bubble nucleation signals are of lower intensity than those obtained from the neutron induced bubble nucleation signals. This phenomenon as observed with tiny droplets is opposite to that observed so far for the larger droplets.

K–P–Burgers equation in negative ion-rich relativistic dusty plasma including the effect of kinematic viscosity

The stationary solution is obtained for the K–P–Burgers equation that describes the nonlinear propagations of dust ion acoustic waves in a multi-component, collisionless, un-magnetized relativistic dusty plasma consisting of electrons, positive and negative ions in the presence of charged massive dust grains. Here, the Kadomtsev–Petviashvili (K–P) equation, three-dimensional (3D) Burgers equation, and K–P–Burgers equations are derived by using the reductive perturbation method including the effects of viscosity of plasma fluid, thermal energy, ion density, and ion temperature on the structure of a dust ion acoustic shock wave (DIASW). The K–P equation predictes the existences of stationary small amplitude solitary wave, whereas the K–P–Burgers equation in the weakly relativistic regime describes the evolution of shock-like structures in such a multi-ion dusty plasma.

Oblique propagation of ion acoustic shock waves in weakly and highly relativistic plasmas with nonthermal electrons and positrons

This work investigates the oblique nonlinear propagation of ion acoustic (IA) shock waves for both weakly and highly relativistic plasmas composed of nonthermal electrons and positrons with relativistic thermal ions. The KdVB-like equation, involving dispersive, weakly transverse dispersive, nonlinearity and dissipative coefficients, is derived employing the well known reductive perturbation method. The integration of this equation is carried out by the $\mathit{tanh}$ method taking the stable shock formation condition into account. The effects of nonthermal electrons and positrons, nonthermal electrons with isothermal positrons, isothermal electrons with nonthermal positrons, and isothermal electrons and positrons on oblique propagation of IA shock waves in weakly relativistic regime are described. Furthermore, the effects of plasma parameters on oblique propagation of IA shock waves in highly relativistic regime are discussed and compared with weakly relativistic case. It is seen that the plasma parameters within certain limits significantly modify the structures of the IA shock waves in both cases. The results may be useful for better understanding of the interactions of charged particles with extra-galactic jets as well as astrophysical compact objects.

Experimental investigation of flow induced dust acoustic shock waves in a complex plasma

We report on experimental observations of flow induced large amplitude dust-acoustic shock waves in a complex plasma. The experiments have been carried out in a Π shaped direct current glow discharge experimental device using kaolin particles as the dust component in a background of Argon plasma. A strong supersonic flow of the dust fluid is induced by adjusting the pumping speed and neutral gas flow into the device. An isolated copper wire mounted on the cathode acts as a potential barrier to the flow of dust particles. A sudden change in the gas flow rate is used to trigger the onset of high velocity dust acoustic shocks whose dynamics are captured by fast video pictures of the evolving structures. The physical characteristics of these shocks are delineated through a parametric scan of their dynamical properties over a range of flow speeds and potential hill heights. The observed evolution of the shock waves and their propagation characteristics are found to compare well with model numerical results based on a modified Korteweg-de-Vries-Burgers type equation.

Ionospheric disturbances triggered by the 25 April, 2015 M7.8 Gorkha earthquake, Nepal: Constraints from GPS TEC measurements

The ionosphere response to the April 11, 2015 (Mw 7.8) Gorkha earthquake, occurring in the Himalayan arc, is analysed using GPS Total Electron Content (TEC) measurements, from GPS sites in Nepal and India, situated both close to and far from the epicentre. In the near field, the Coseismic Ionospheric disturbance (CID) following the earthquake rupture propagation arrive east of the epicentre, within 5–7min with a propagation velocity of 980m/s, equal to the speed of the shock acoustic waves at the ionospheric heights, and on to the west with a reduced speed of 650m/s, within 8–11min, after the earthquake occurrence. The phenomenon of CID splitting into two modes, east and west of the epicentre is observed. In the far-field region, up to epicentral distances of 2200km, Rayleigh wave induced ionospheric disturbance are recorded with a propagation speed of 2.6km/s. Higher TEC amplitude of 0.2–1.5 TECU is observed east of the epicentre compared to the west with 0.1–0.3 TECU. The characteristics of this dip-slip earthquake are well projected in the TEC waveforms. The ambient magnetic field in the mid-latitudes prohibited the propagation of ionospheric disturbance in the northward direction. In the present study the observed primary CID is essentially in congruence with the rupture propagation of the earthquake in E-SE direction.

Effect of ion viscosity on dust ion-acoustic shock waves in a nonextensive magnetoplasma

The nonlinear features of dust ion-acoustic shock waves (DIASWs) in a magnetoplasma containing cold positive ions, nonextensive electrons, and immobile negatively charged dust grains taking into account the cold ion kinematic viscosity are investigated. The reductive perturbation technique is used to derive a Zakharov-Kuznetsov-Burgers (ZK-Burgers). It is found that the fundamental properties of the DIASWs are significantly modified by the different system parameters such as the nonextensive parameter, the ion gyrofrequency, the dust concentration, the viscosity parameter, and the direction cosines. Also, the polarities (positive and negative shocks) of the potential are found to exist in the plasma under consideration. The implications of our results may be used in understanding the acoustic shock waves propagation in laboratory and space plasmas.

Variational principle, conservation laws and exact solutions for dust ion acoustic shock waves modeling modified Burger equation

The nonlinear dust ion acoustic (DIA) shock waves have been investigated in one-dimensional, collisionless and unmagnetized dusty plasma consisting of mobile ion, vortex-like electron and charge fluctuating static dust particles. The basic set of fluid equations is reduced to the modified Burger equation by using the reductive perturbation method. The effects of dust grain charge fluctuation and vortex-like (trapped) electron are found to modify the properties of the DIA shock waves significantly. By the semi-inverse method, a variational principle, and conservation laws for the modified Burger equation are obtained. It is shown that the modified Burger equation is non-integrable using Painlevé analysis. A set of new exact solutions are obtained by the auto-Bäcklund transformations. Finally, we will study the physical meanings of solutions.

Time fractional effect on ion acoustic shock waves in ion-pair plasma

The nonlinear properties of ion acoustic shock waves are studied. The Burgers equation is derived and converted into the time fractional Burgers equation by Agrawal’s method. Using the Adomian decomposition method, shock wave solutions of the time fractional Burgers equation are constructed. The effect of the time fractional parameter on the shock wave properties in ion-pair plasma is investigated. The results obtained may be important in investigating the broadband electrostatic shock noise in D- and F-regions of Earth’s ionosphere.

Observation of dust acoustic shock wave in a strongly coupled dusty plasma

Dust acoustic shock wave is observed in a strongly coupled laboratory dusty plasma. A supersonic flow of charged microparticles is allowed to perturb a stationary dust fluid to excite dust acoustic shock wave. The evolution process beginning with steepening of initial wave front and then formation of a stable shock structure is similar to the numerical results of the Korteweg-de Vries-Burgers equation. The measured Mach number of the observed shock wave agrees with the theoretical results. Reduction of shock amplitude at large distances is also observed due to the dust neutral collision and viscosity effects. The dispersion relation and the spatial damping of a linear dust acoustic wave are also measured and compared with the relevant theory.

Effect of pulse duration on the acoustic frequency emissions during the laser-induced breakdown of atmospheric air.

Acoustic shock waves (ASWs) in the frequency range of 30-120kHz generated during laser-induced breakdown (LIB) of ambient air using 7ns and 30ps pulse durations are studied. The specific frequency range and peak amplitudes are observed to be different for nanosecond (ns) and picosecond (ps) LIB. The ASW frequencies for ps-LIB lie between 90 and 120kHz with one dominant peak, whereas for ns-LIB, two dominant peaks with frequencies in the 30-70kHz and 80-120kHz range are observed. These frequencies are observed to be laser pulse intensity dependent. With increasing energy of ns laser pulses, acoustic frequencies move toward the audible frequency range. The variation in the acoustic parameters, such as peak-to-peak pressures, signal energy, frequency and acoustic pulse widths as a function of laser energy, for two different pulse durations are presented in detail and compared. The acoustic emissions are observed to be higher for ns-LIB than ps-LIB, indicating higher conversion efficiency of optical energy into mechanical energy.

Seismo-ionospheric anomalies and implications from recent GNSS observations in India and South-East Asia

The lithosphere and the atmosphere/ionosphere, continuously exchange energy through various coupling mechanisms. Earthquake creates waves of energy, e.g. direct shock acoustic waves (SAWs) and Rayleigh wave induced acoustic waves (RAWs). In the event of an earthquake occurring beneath the sea, atmospheric gravity waves (AGWs) are also generated. If the earthquake is large enough (Mw > 6), SAWs, RAWs and AGWs induce detectable ionospheric plasma perturbations. Inferring the seismological information from these seismo-ionospheric manifestations is the subject that pertains to ionospheric seismology. Both ground and satellite based advanced radio techniques are being used in monitoring ionospheric plasma perturbations. In this study, seismo-ionospheric anomalies and implications from recent GNSS observations in India and South-East Asia are discussed, mainly pertaining to the following. (1) From the ionospheric plasma response to 2015 Nepal earthquake, the estimated group velocity for Andaman and Indian shield regions are 2100 ms−1 and 3900 ms−1 respectively and validated from ground measurements. (2) Atmospheric acoustic resonance at 4.0 mHz and a train of wave packet of TEC variation resulting from the beat phenomenon observed at the site ‘umlh’ and (3) GNSS-based tsunami warning which is going to be promising tool in augmenting the existing tsunami warning systems.

Ion acoustic shock and solitary waves in highly relativistic plasmas with nonextensive electrons and positrons

The Korteweg-de Vries Burgers (KdVB)-like equation is derived to study the characteristics of nonlinear propagation of ion acoustic solitions in a highly relativistic plasma containing relativistic ions and nonextensive distribution of electrons and positrons using the well known reductive perturbation technique. The KdVB-like equation is solved employing the Bernoulli's equation method taking unperturbed positron to electron concentration ratio, electron to positron temperature ratio, strength of nonextensivity, ion kinematic viscosity, and highly relativistic streaming factor. It is found that these parameters significantly modify the structures of the solitonic excitation. The ion acoustic shock profiles are observed due to the influence of ion kinematic viscosity. In the absence of dissipative term to the KdVB equation, compressive and rarefactive solitons are observed in case of superthermality, but only compressive solitons are found for the case of subthermality.

Propagation of Electron Acoustic Soliton, Periodic and Shock Waves in Dissipative Plasma with a q-Nonextensive Electron Velocity Distribution

The nonlinear properties of small amplitude electron-acoustic (EA) solitary and shock waves in a homogeneous system of unmagnetized collisionless plasma with nonextensive distribution for hot electrons have been investigated. A reductive perturbation method used to obtain the Kadomstev–Petviashvili-Burgers equation. Bifurcation analysis has been discussed for non-dissipative system in the absence of Burgers term and reveals different classes of the traveling wave solutions. The obtained solutions are related to periodic and soliton waves and their behavior are shown graphically. In the presence of the Burgers term, the EXP-function method is used to solve the Kadomstev–Petviashvili-Burgers equation and the obtained solution is related to shock wave. The obtained results may be helpful in better conception of waves propagation in various space plasma environments as well as in inertial confinement fusion laboratory plasmas.

Oblique shock waves in a two electron temperature superthermally magnetized plasma

A study is presented for the oblique propagation of low-frequency ion acoustic (IA) shock waves in a magnetized plasma consisting of cold ions and two temperature superthermally distributed electrons. A nonlinear Korteweg de-Vries-Burger (KdV-Burger) equation is obtained by using the reductive perturbation method (RPM) which governs the dynamics of the IA shock wave. Using the solution of KdV-Burger equation, the characteristics of the IA shock wave have been studied for various plasma parameters. The combined effects of the cold to hot electron temperature ratio ( $\sigma$ ), the density ratio of hot electrons to ions ( $f$ ), the superthermality of cold and hot electrons ( $\kappa_{c}, \kappa_{h}$ ), the strength of the magnetic field ( $\omega_{ci}$ ), and the obliqueness ( $\theta$ ), significantly influence the profile of the shock wave. The findings in the present study could be important for the electrostatic wave structures in the Saturn’s magnetosphere, where two temperature electrons exist with a kappa distribution.

Characterization of Pressure Transients Generated by Nanosecond Electrical Pulse (nsEP) Exposure.

The mechanism(s) responsible for the breakdown (nanoporation) of cell plasma membranes after nanosecond pulse (nsEP) exposure remains poorly understood. Current theories focus exclusively on the electrical field, citing electrostriction, water dipole alignment and/or electrodeformation as the primary mechanisms for pore formation. However, the delivery of a high-voltage nsEP to cells by tungsten electrodes creates a multitude of biophysical phenomena, including electrohydraulic cavitation, electrochemical interactions, thermoelastic expansion, and others. To date, very limited research has investigated non-electric phenomena occurring during nsEP exposures and their potential effect on cell nanoporation. Of primary interest is the production of acoustic shock waves during nsEP exposure, as it is known that acoustic shock waves can cause membrane poration (sonoporation). Based on these observations, our group characterized the acoustic pressure transients generated by nsEP and determined if such transients played any role in nanoporation. In this paper, we show that nsEP exposures, equivalent to those used in cellular studies, are capable of generating high-frequency (2.5 MHz), high-intensity (>13 kPa) pressure transients. Using confocal microscopy to measure cell uptake of YO-PRO®-1 (indicator of nanoporation of the plasma membrane) and changing the electrode geometry, we determined that acoustic waves alone are not responsible for poration of the membrane.