Influence of anisotropy on the structure of an ion-sound wave

We study the influence of magnetic field on the ion-sound disturbance of a weakly ionized plasma ahead of a strong shock wave of the neutral component. Different regimes (subsonic, sonic, and supersonic) are studied. Main attention is paid to the case of formation of a discontinuous field in the plasma. Radiophysical Research Institute, St. Petersburg University, St. Petersburg, Russia. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 42, No. 2, pp. 120–128, February 1999.     

Study on the Mach and regular reflections of shock wave

Journal of Visualization - While a moving incident shock wave moves through a sharp compression ramp with the fixed angle, θr, the incident shock wave is reflected by the ramp surface and the...     

Effect of external power supply to a shock layer on the shock wave structure

A physical model that describes the structure of a 1D shock wave in a gas containing a moving heat source is put forward. A stationary equation for the profile of a shock wave in a gas with an arbitrary-shape heat source that is at rest relative to this wave is derived. Analytical solutions to this equation make it possible to analyze the flow pattern in the case of external power supply.     

Ponderomotive transport of a variable-charge granule in a dusty plasma in the field of an intense ion-sound wave

The ponderomotive force acting on a variable-charge granule in a dusty plasma from an intense ion-sound wave is considered. Allowance for oscillations of the granule charge in the field of an ion-sound wave makes it possible to reveal new components of this force that are proportional to the wave vector of the field and the cube of its amplitude. These components do not vanish in the case of a uniform field and also lead to a directed transport of the dust plasma fraction.     

Influence of radiation cross section uncertainties on shock wave structure

This numerical study investigates the sensitivity of non-equilibrium shockwave structure to uncertainties in (a) the ground and excited state continuum radiative cross section and (b) the bound-bound radiative cross section in a three level (ground, excited, and free electronic states considered) argon-like gas at Mach 18 and a pressure of 1 cm Hg. Changing the values of the radiative cross sections by an order of magnitude does not significantly influence the relaxation region; however, a large change occurs in not only the magnitude but also the extent of both the electron and excited state precursors. Increasing either the ground state continuum or the bound-bound cross section decreases the number of free electrons in front of the shock wave. These cross sections also influence the extent of the electron precursor through their influence on the ratio of the electrons produced by ground state photoionization to those produced by ground state photoexcitation followed by excited state photoionization. The bound-bound cross section also controls the excited state precursor, because the production of excited states is entirely due to line radiation. Increasing the excited state photoionization cross section increases both the magnitude and extent of the electron precursor, because the cross section influences the ratio of the two processes that compete to produce free electrons, and at the same time it influences the magnitude of the excited state precursor.     

Influence of electron-atom cross section uncertainties on shock wave structure

The exact value of the electron-atom collisional ionization cross section for argon is not accurately known. The purpose of the present research is to determine numerically the effect of varying the magnitude of the electron-atom cross section on nonequilibrium shock-wave structure. Mach 18 shock waves propagating into an argon-like gas at 1 cm-Hg and 300°K have been analyzed. Thermal, ionizational, and excitational non-equilibrium are considered in the relaxation region behind the shock wave. Electrons in the relaxation region are formed by a two-step collisional process, wherein the atom is first excited and then it is ionized. The precursor is formed by ground and excited state continuum radiation and line radiation which is emitted, but not reabsorbed, in the region behind the shock wave. When the electron-atom ionization cross section is varied from 1·86 × 10^?4to 1·86 × 10^?2cm²/erg, the results show that (1) it influences the coupling between the precursor and relaxation region through the radiative source functions, (2) it does not influence the distance necessary to attain equilibrium behind the shock wave, (3) it inversely influences the magnitude of the precursor ionization, and excitation, and (4) it inversely influences both the free electron and excited state population in the relaxation layer.     

Classification of shock wave reflections from a wedge. Part 2: Experimental and numerical simulations of different types of Mach reflections

Classification of various types of the reflections of a shock wave over straight wedge is supposed. The idea about entire reflection phenomenon as a result of interaction of two processes—the shock wave refection process and the flow deflection process—serves as a basis for the classification. To recognize the types of reflection, changes in the shapes of the reflected wave, Mach stem and contact surface are taken into account. The boundaries and domains of existence for various types of reflection are reported. New names for some types of reflection are proposed.     

Classification of shock wave reflections from a wedge. Part 1: Boundaries and domains of existence for different types of reflections

Classification of various types of the reflections of a shock wave over straight wedge is supposed. The idea about entire reflection phenomenon as a result of interaction of two processes—the shock wave refection process and the flow deflection process—serves as a basis for the classification. To recognize the types of reflection, changes in the shapes of the reflected wave, Mach stem and contact surface are taken into account. The boundaries and domains of existence for various types of reflection are reported. New names for some types of reflection are proposed.     

Chaotic matter shock wave of an open system

We investigate a one-dimensional open Bose-Einstein condensate with attractive interaction,by considering the effect of feeding from nonequilibrium thermal cloud and applying the time-periodic inverted-harmonic potential.Using the direct perturbation method and the exact shock wave solution of the stationary Gross-Pitaevskii equation,we obtain the chaotic perturbed solution and the Melnikov chaotic regions.Based on the analytical and the numerical methods,the influence of the feeding strength on the chaotic motion is revealed.It is shown that the chaotic regions could be enlarged by reducing the feeding strength and the increase of feeding strength plays a role in suppressing chaos.In the case of "nonpropagated" shock wave with fixed boundary,the number of condensed atoms increases faster as the feeding strength increases.However,for the free boundary the metastable shock wave with fixed front density oscillates its front position and atomic number aperiodically,and their amplitudes decay with the increase of the feeding strength.     

Molecular dynamics study on the structure of shock wave front in a hard-core fluid

Stationary normal shock waves in a hard-core fluid were simulated via molecular dynamics. Profiles of various physical quantities near the shock front were calculated, and their dependence on the fluid density and the shock Mach number was studied.     

Effect of rippled laser beam on excitation of ion acoustic wave

Growth of a radially symmetrical ripple, superimposed on a Gaussian laser beam in collisional unmagnetised plasma is investigated. From numerical computation, it is observed that self-focusing of main beam as well as ripple determine the growth dynamics of ripple with the distance of propagation. The effect of growing ripple on excitation of ion acoustic wave (IAW) has also been studied.     

Study of the fine structure of charged particles flows in the bow shock wave

The paper presents a study of the bow shock wave based on the data from an energy ion spectrometer installed on board the satellite Prognoz 8. In the experiment both the vector of total ion flux and the ion energy spectra were measured, the energy range being from 0·16 to 4·2 keV with the time resolution of about 1 sec. The paper describes a statistical data processing of basic parameters from several consecutive shock wave crossings, following each other in short time intervals. The results, compared with the behaviour of other parameters characteristic for this region, enable to draw a qualitative conclusion about the processes responsible for fast thermalization in the region after the shock wave front.Presented at the Fifth Scientific Assembly of IAGA in Prague, 1985.We would like to express our thanks to Dr. Russel who kindly supplied the data from ISEE-3 mag. field measurements. We are grateful to Dr. Vaisberg for many valuable suggestions concerning data processing and interpretation.     

Effect of an Xe additive on the degree of translational nonequilibrium of an He-O2-H2 mixture in a shock wave front

Computer simulations of the experimentally observed detonation threshold shift upon adding small amounts of Xe with the use of the direct simulation Monte Carlo method once again confirmed that this effect is associated with a substantial increase in the degree of translational nonequilibrium in the shock wave front. It was demonstrated that, when the presence of hydrogen in the mixture is taken into account, the calculated degree of translational nonequilibrium becomes higher. In addition, the effect of Xe was observed to grow stronger as the Xe concentration was decreased from 0.5 to 0.25%.     

The effect of ion motion on the reflection of an electromagnetic wave from plasma

An electromagnetic wave with electric vector parallel to the plasma boundary falls from a vacuum on a half-space filled with magnetoactive plasma and bounded by a particle-reflecting wall. A comparison is made of the effect of thermal motion of electrons and ions on the boundary, on the coefficient of reflection and on the absorbed energy.