Science.gov

Sample records for ion sound wave

  1. Fundamental plasma emission involving ion sound waves

    NASA Technical Reports Server (NTRS)

    Cairns, Iver H.

    1987-01-01

    The theory for fundamental plasma emission by the three-wave processes L + or - S to T (where L, S and T denote Langmuir, ion sound and transverse waves, respectively) is developed. Kinematic constraints on the characteristics and growth lengths of waves participating in the wave processes are identified. In addition the rates, path-integrated wave temperatures, and limits on the brightness temperature of the radiation are derived.

  2. Negative ion sound solitary waves revisited

    NASA Astrophysics Data System (ADS)

    Cairns, R. A.; Cairns

    2013-12-01

    Some years ago, a group including the present author and Padma Shukla showed that a suitable non-thermal electron distribution allows the formation of ion sound solitary waves with either positive or negative density perturbations, whereas with Maxwellian electrons only a positive density perturbation is possible. The present paper discusses the qualitative features of this distribution allowing the negative waves and shared with suitable two-temperature distributions.

  3. Second harmonic plasma emission involving ion sound waves

    NASA Technical Reports Server (NTRS)

    Cairns, Iver H.

    1987-01-01

    The theory for second harmonic plasma emission by the weak turbulence (or random phase) processes L + L + or - S to T, proceeding in two three-wave steps, L + or - S to L prime and L + L prime to T, where L, S and T denote Langmuir, ion sound and electromagnetic waves, respectively, is developed. Kinematic constraints on the characteristics and growth lengths of waves participating in the wave processes, and constraints on the characteristics of the source plasma, are derived. Limits on the brightness temperature of the radiation and the levels of the L prime and S waves are determined. Expressions for the growth rates and path-integrated wave temperatures are derived for simple models of the wave spectra and source plasma.

  4. Solitary dust sound waves in a plasma with two-temperature ions and distributed grain size

    SciTech Connect

    Prudskikh, V. V.

    2009-01-15

    The propagation of weakly nonlinear dust sound waves in a dusty plasma containing two different-temperature ion species is explored. The nonlinear equations describing both the quadratic and cubic plasma nonlinearities are derived. It is shown that the properties of dust sound waves depend substantially on the grain size distribution. In particular, for solitary dust sound waves with a positive potential to exist in a plasma with distributed grain size, it is necessary that the difference between the temperatures of two ion species be larger than that in the case of equal-size grains.

  5. Dynamic of Langmuir and Ion-Sound Waves in Type 3 Solar Radio Sources

    NASA Technical Reports Server (NTRS)

    Robinson, P. A.; Willes, A. J.; Cairns, I. H.

    1993-01-01

    The evolution of Langmuir and ion-sound waves in type 3 sources is investigated, incorporating linear growth, linear damping, and nonlinear electrostatic decay. Improved estimates are obtained for the wavenumber range of growing waves and the nonlinear coupling coefficient for the decay process. The resulting prediction for the electrostatic decay threshold is consistent with the observed high-field cutoff in the Langmuir field distribution. It is shown that the conditions in the solar wind do not allow a steady state to be attained; rather, bursty linear and nonlinear interactions take place, consistent with the highly inhomogeneous and impulsive waves actually observed. Nonlinear growth is found to be fast enough to saturate the growth of the parent Langmuir waves in the available interaction time. The resulting levels of product Langmuir and ion-sound waves are estimated theoretically and shown to be consistent with in situ ISEE 3 observations of type 3 events at 1 AU. Nonlinear interactions slave the growth and decay of product sound waves to that of the product Langmuir waves. The resulting probability distribution of ion-sound field strengths is predicted to have a flat tail extending to a high-field cutoff. This prediction is consistent with statistics derived here from ISEE 3 observations. Agreement is also found between the frequencies of the observed waves and predictions for the product S waves. The competing processes of nonlinear wave collapse and quasilinear relaxation are discussed, and it is concluded that neither is responsible for the saturation of Langmuir growth. When wave and beam inhomogeneities are accounted for, arguments from quasi-linear relaxation yield an upper bound on the Langmuir fields that is too high to be relevant. Nor are the criteria for direct wave collapse of the beam-driven waves met, consistent with earlier simulation results that imply that this process is not responsible for saturation of the beam instability. Indeed, even

  6. Dynamics of Langmuir and ion-sound waves in type III solar radio sources

    NASA Technical Reports Server (NTRS)

    Robinson, P. A.; Willes, A. J.; Cairns, I. H.

    1993-01-01

    The study traces the evolution of Langmuir and ion-sound waves in type III sources, incorporating linear growth, linear damping, and nonlinear electrostatic decay. Improved estimates are obtained for the wavenumber range of growing waves and the nonlinear coupling coefficient for the decay process. It is shown that the conditions in the solar wind do not allow a steady state to be attained; instead, bursty linear and nonlinear interactions take place, consistent with the highly inhomogeneous and impulsive waves actually observed. Nonlinear growth is found to be rapid enough to saturate the growth of the parent Langmuir waves in the available interaction time. The competing processes of nonlinear wave collapse and quasi-linear relaxation are discussed, and it is concluded that neither is responsible for the saturation of Langmuir growth.

  7. Sound wave transmission (image)

    MedlinePlus

    When sounds waves reach the ear, they are translated into nerve impulses. These impulses then travel to the brain where they are interpreted by the brain as sound. The hearing mechanisms within the inner ear, can ...

  8. Nonlinear theory of ionic sound waves in a hot quantum-degenerate electron-positron-ion plasma

    SciTech Connect

    Dubinov, A. E. Sazonkin, M. A.

    2010-11-15

    A collisionless nonmagnetized e-p-i plasma consisting of quantum-degenerate gases of ions, electrons, and positrons at nonzero temperatures is considered. The dispersion equation for isothermal ionic sound waves is derived and analyzed, and an exact expression is obtained for the linear velocity of ionic sound. Analysis of the dispersion equation has made it possible to determine the ranges of parameters in which nonlinear solutions in the form of solitons should be sought. A nonlinear theory of isothermal ionic sound waves is developed and used for obtaining and analyzing the exact solution to the system of initial equations. Analysis has been carried out by the method of the Bernoulli pseudopotential. The ranges of phase velocities of periodic ionic sound waves and soliton velocities are determined. It is shown that in the plasma under investigation, these ranges do not overlap and that the soliton velocity cannot be lower than the linear velocity of ionic sound. The profiles of physical quantities in a periodic wave and in a soliton are constructed, as well as the dependences of the velocity of sound and the critical velocity on the ionic concentration in the plasma. It is shown that these velocities increase with the ion concentration.

  9. Plasma waves produced by the xenon ion beam experiment on the Porcupine sounding rocket

    NASA Technical Reports Server (NTRS)

    Kintner, P. M.; Kelley, M.

    1982-01-01

    The production of electrostatic ion cyclotron waves by a perpendicular ion beam in the F-region ionosphere is described. The ion beam experiment was part of the Porcupine program and produced electrostatic hydrogen cyclotron waves just above harmonics of the hydrogen cyclotron frequency. The plasma process may be thought of as a magnetized background ionosphere through which an unmagnetized beam is flowing. The dispersion equation for this hypothesis is constructed and solved. Preliminary solutions agree well with the observed plasma waves.

  10. Kinetic Effects on the Ion Sound Waves Generated by Stimulated Brillouin Scattering of a Spatially Smoothed Laser Beam

    NASA Astrophysics Data System (ADS)

    Riconda, Caterina; Hüller, Stefan; Myatt, Jason; Pesme, Denise

    Stimulated Brillouin Scattering (SBS) can drive ion sound waves to amplitudes such that steepening and particle kinetic effects occur. Such phenomena have been studied recently in spatial volumes corresponding to a single laser speckle, in two [Cohen, B. I. et al. Phys. Plasmas 4, 956 (1997)], and three spatial dimensions [Vu, H. X., Phys. Plasmas 4, 1841 (1997)]. We analyze the results of 2D kinetic simulations modeling the evolution of SBS in the case of a spatially smoothed laser beam interacting with a plasma containing many speckles. For this purpose, we have coupled a 2D particle-in-cell code to a 2D non-paraxial electromagnetic wave solver. The generation of a fast ion population is observed to initially take place in the most intense hot spots, resulting in a decrease of the amplitude of the ion sound wave amplitude generated by SBS in these hot spots. SBS activity is consequently reduced in the most intense laser speckles, so that the overall backscattering SBS reflectivity drops considerably below the values expected from models that do not account for particle kinetics and/or nonlinear hydrodynamics.

  11. Ion heating, burnout of the high-frequency field, and ion sound generation under the development of a modulation instability of an intense Langmuir wave in a plasma

    SciTech Connect

    Kirichok, A. V. Kuklin, V. M.; Pryimak, A. V.; Zagorodny, A. G.

    2015-09-15

    The development of one-dimensional parametric instabilities of intense long plasma waves is considered in terms of the so-called hybrid models, with electrons being treated as a fluid and ions being regarded as particles. The analysis is performed for both cases when the average plasma field energy is lower (Zakharov's hybrid model—ZHM) or greater (Silin's hybrid model—SHM) than the plasma thermal energy. The efficiency of energy transfer to ions and to ion perturbations under the development of the instability is considered for various values of electron-to-ion mass ratios. The energy of low-frequency oscillations (ion-sound waves) is found to be much lower than the final ion kinetic energy. We also discuss the influence of the changes in the damping rate of the high-frequency (HF) field on the instability development. The decrease of the absorption of the HF field inhibits the HF field burnout within plasma density cavities and gives rise to the broadening of the HF spectrum. At the same time, the ion velocity distribution tends to the normal distribution in both ZHM and SHM.

  12. Ion heating, burnout of the high-frequency field, and ion sound generation under the development of a modulation instability of an intense Langmuir wave in a plasma

    NASA Astrophysics Data System (ADS)

    Kirichok, A. V.; Kuklin, V. M.; Pryimak, A. V.; Zagorodny, A. G.

    2015-09-01

    The development of one-dimensional parametric instabilities of intense long plasma waves is considered in terms of the so-called hybrid models, with electrons being treated as a fluid and ions being regarded as particles. The analysis is performed for both cases when the average plasma field energy is lower (Zakharov's hybrid model—ZHM) or greater (Silin's hybrid model—SHM) than the plasma thermal energy. The efficiency of energy transfer to ions and to ion perturbations under the development of the instability is considered for various values of electron-to-ion mass ratios. The energy of low-frequency oscillations (ion-sound waves) is found to be much lower than the final ion kinetic energy. We also discuss the influence of the changes in the damping rate of the high-frequency (HF) field on the instability development. The decrease of the absorption of the HF field inhibits the HF field burnout within plasma density cavities and gives rise to the broadening of the HF spectrum. At the same time, the ion velocity distribution tends to the normal distribution in both ZHM and SHM.

  13. Just How Does Sound Wave?

    ERIC Educational Resources Information Center

    Shipman, Bob

    2006-01-01

    When children first hear the term "sound wave" perhaps they might associate it with the way a hand waves or perhaps the squiggly line image on a television monitor when sound recordings are being made. Research suggests that children tend to think sound somehow travels as a discrete package, a fast-moving invisible thing, and not something that…

  14. SU-E-J-138: On the Ion Beam Range and Dose Verification in Hadron Therapy Using Sound Waves

    SciTech Connect

    Fourkal, E; Veltchev, I; Gayou, O; Nahirnyak, V

    2015-06-15

    Purpose: Accurate range verification is of great importance to fully exploit the potential benefits of ion beam therapies. Current research efforts on this topic include the use of PET imaging of induced activity, detection of emerging prompt gamma rays or secondary particles. It has also been suggested recently to detect the ultrasound waves emitted through the ion energy absorption process. The energy absorbed in a medium is dissipated as heat, followed by thermal expansion that leads to generation of acoustic waves. By using an array of ultrasound transducers the precise spatial location of the Bragg peak can be obtained. The shape and intensity of the emitted ultrasound pulse depend on several variables including the absorbed energy and the pulse length. The main objective of this work is to understand how the ultrasound wave amplitude and shape depend on the initial ion energy and intensity. This would help guide future experiments in ionoacoustic imaging. Methods: The absorbed energy density for protons and carbon ions of different energy and field sizes were obtained using Fluka Monte Carlo code. Subsequently, the system of coupled equations for temperature and pressure is solved for different ion pulse intensities and lengths to obtain the pressure wave shape, amplitude and spectral distribution. Results: The proposed calculations show that the excited pressure wave amplitude is proportional to the absorbed energy density and for longer ion pulses inversely proportional to the ion pulse duration. It is also shown that the resulting ionoacoustic pressure distribution depends on both ion pulse duration and time between the pulses. Conclusion: The Bragg peak localization using ionoacoustic signal may eventually lead to the development of an alternative imaging method with sub-millimeter resolution. It may also open a way for in-vivo dose verification from the measured acoustic signal.

  15. Sound Waves Levitate Substrates

    NASA Technical Reports Server (NTRS)

    Lee, M. C.; Wang, T. G.

    1982-01-01

    System recently tested uses acoustic waves to levitate liquid drops, millimeter-sized glass microballoons, and other objects for coating by vapor deposition or capillary attraction. Cylindrical contactless coating/handling facility employs a cylindrical acoustic focusing radiator and a tapered reflector to generate a specially-shaped standing wave pattern. Article to be processed is captured by the acoustic force field under the reflector and moves as reflector is moved to different work stations.

  16. Ion sound instability driven by the ion flows

    SciTech Connect

    Koshkarov, O.; Smolyakov, A. I.; Kaganovich, I. D.; Ilgisonis, V. I.

    2015-05-15

    Ion sound instabilities driven by the ion flow in a system of a finite length are considered by analytical and numerical methods. The ion sound waves are modified by the presence of stationary ion flow resulting in negative and positive energy modes. The instability develops due to coupling of negative and positive energy modes mediated by reflections from the boundary. It is shown that the wave dispersion due to deviation from quasineutrality is crucial for the stability. In finite length system, the dispersion is characterized by the length of the system measured in units of the Debye length. The instability is studied analytically and the results are compared with direct, initial value numerical simulations.

  17. Hydrodynamic ion sound instability in systems of a finite length

    NASA Astrophysics Data System (ADS)

    Koshkarov, O.; Chapurin, O.; Smolyakov, A.; Kaganovich, I.; Ilgisonis, V.

    2016-09-01

    Plasmas permeated by an energetic ion beam is prone to the kinetic ion-sound instability that occurs as a result of the inverse Landau damping for ion velocity. It is shown here that in a finite length system there exists another type of the ion sound instability which occurs for v02 wave coupling mediated by reflections from the walls. Analytical theory is developed and is compared with results of direct initial value numerical simulations. Formally analogous model is applicable for the excitation of the lower-hybrid waves in Hall thruster. It is expected that this mechanism of ion sound and lower hybrid instabilities may be operative in E × B plasma discharges in which the ion beam is created by the application of the external voltage.

  18. Waves and Sound, An Experiment that Walks.

    ERIC Educational Resources Information Center

    Brunschwig, Fernand

    An experiment on sound waves, developed for non-science majors in a college physics course, is described. The student investigates the interference of two sound waves and measures and wavelength as he uses a prerecorded tape and a cassette player. The student is tutored by the cassette tape recorder, which also produces the overlapping sound…

  19. Sound wave propagation through glow discharge plasma

    NASA Astrophysics Data System (ADS)

    Stepaniuk, Vadim P.

    This work investigates the use of glow discharge plasma for acoustic wave manipulation. The broader goal is the suppression of aerodynamic noise using atmospheric glow discharge plasma as a sound barrier. Part of the effort was devoted to the development of a system for the generation of a large volume stable DC glow discharge in air both at atmospheric and at reduced pressures. The single tone sound wave propagation through the plasma was systematically studied. Attenuation of the acoustic wave passing through the glow discharge was measured for a range of experimental conditions including different discharge currents, electrode configurations, air pressures and sound frequencies including audible sound and ultrasound. Sound attenuation by glow discharge plasma as high as -28 dB was recorded in the experiments. Two types of possible mechanisms were considered that can potentially cause the observed sound attenuation. One is a global mechanism and the other is a local mechanism. The global mechanism considered is based on the reflection and refraction of acoustic wave due to the gas temperature gradients that form around the plasma. The local mechanism, on the other hand, is essentially the interaction of the acoustic wave with the plasma as it propagates inside the discharge and it can be viewed as a feedback system. Detailed temperature measurements, using laser-induced Rayleigh scattering technique, were carried out in the glow discharge plasma in order to evaluate the role of global mechanism in the observed attenuation. These measurements were made for a range of conditions in the atmospheric glow discharge. Theoretical analysis of the sound attenuation was carried out to identify the physical mechanism for the observed sound attenuation by plasma. It was demonstrated that the global mechanism is the dominant mechanism of sound attenuation. As a result of this study, the potentials and limitations of the plasma noise suppression technology were determined and

  20. Reflection of underwater sound from surface waves.

    PubMed

    Tindle, Chris T; Deane, Grant B; Preisig, James C

    2009-01-01

    A tank experiment has been conducted to measure reflection of underwater sound from surface waves. Reflection from a wave crest leads to focusing and caustics and results in rapid variation in the received waveform as the surface wave moves. Theoretical results from wavefront modeling show that interference of three surface reflected eigenrays for each wave crest produces complicated interference waveforms. There is good agreement between theory and experiment even on the shadow side of caustics where there are two surface reflected arrivals but only one eigenray.

  1. Crova's Disc: A Way to Make Sound Waves "Visible."

    ERIC Educational Resources Information Center

    Hastings, R. B.

    1981-01-01

    Explained are the differences between and offered are examples of longitudinal and transverse sound waves. Described is the construction of the Crova's Disc, a device used in the teaching of the propagation and properties of sound waves. (DS)

  2. Experiments on current-driven three-dimensional ion sound turbulence. I - Return-current limited electron beam injection. II - Wave dynamics

    NASA Technical Reports Server (NTRS)

    Stenzel, R. L.

    1978-01-01

    Pulsed electron beam injection into a weakly collisional magnetized background plasma is investigated experimentally; properties of the electron beam and background plasma, as well as the low-frequency instabilities and wave dynamics, are discussed. The current of the injected beam closes via a field-aligned return current of background electrons. Through study of the frequency and wavenumber distribution, together with the electron distribution function, the low-frequency instabilities associated with the pulsed injection are identified as ion acoustic waves driven unstable by the return current. The frequency cut-off of the instabilities predicted from renormalized plasma turbulence theory, has been verified experimentally.

  3. Radio wave propagation and acoustic sounding

    NASA Astrophysics Data System (ADS)

    Singal, S. P.

    Radio wave propagation of the decimetric and centimetric waves depends to a large extent on the boundary layer meteorological conditions which give rise to severe fadings, very often due to multipath propagation. Sodar is one of the inexpensive remote sensing techniques which can be employed to probe the boundary layer structure. In the paper a historical perspective has been given of the simultaneously conducted studies on radio waves and sodar at various places. The radio meteorological information needed for propagation studies has been clearly spelt out and conditions of a ray path especially in the presence of a ducting layer have been defined as giving rise to fading or signal enhancement conditions. Finally the potential of the sodar studies to obtain information about the boundary layer phenomena has been stressed, clearly spelling out the use of acoustic sounding in radio wave propagation studies.

  4. WAVE: Interactive Wave-based Sound Propagation for Virtual Environments.

    PubMed

    Mehra, Ravish; Rungta, Atul; Golas, Abhinav; Ming Lin; Manocha, Dinesh

    2015-04-01

    We present an interactive wave-based sound propagation system that generates accurate, realistic sound in virtual environments for dynamic (moving) sources and listeners. We propose a novel algorithm to accurately solve the wave equation for dynamic sources and listeners using a combination of precomputation techniques and GPU-based runtime evaluation. Our system can handle large environments typically used in VR applications, compute spatial sound corresponding to listener's motion (including head tracking) and handle both omnidirectional and directional sources, all at interactive rates. As compared to prior wave-based techniques applied to large scenes with moving sources, we observe significant improvement in runtime memory. The overall sound-propagation and rendering system has been integrated with the Half-Life 2 game engine, Oculus-Rift head-mounted display, and the Xbox game controller to enable users to experience high-quality acoustic effects (e.g., amplification, diffraction low-passing, high-order scattering) and spatial audio, based on their interactions in the VR application. We provide the results of preliminary user evaluations, conducted to study the impact of wave-based acoustic effects and spatial audio on users' navigation performance in virtual environments.

  5. How to Use a Candle to Study Sound Waves

    ERIC Educational Resources Information Center

    Carvalho, P. Simeão; Briosa, E.; Rodrigues, M.; Pereira, C.; Ataíde, M.

    2013-01-01

    It is well known that sound waves in air are longitudinal waves. Although teachers use analogies such as compressing horizontal springs to demonstrate what longitudinal waves look like, students still present some difficulty in understanding that (1) sound waves correspond to oscillations of air particles, and (2) there is no "air flow"…

  6. Thermodynamic effect of the ion sound instability in the ionosphere

    SciTech Connect

    Khazanov, G.V.; Gombosi, T.I.; Gorbachev, O.A.

    1994-04-01

    During geomagnetic disturbances when the ring current interacts intensely with the plasmasphere, the plasma of this region undergoes a strong heating due to an ion cyclotron instability. This is followed by the transfer of heat along geomagnetic field lines from the heating region to the ionosphere. One of the results of this process is the formation of a non isothermal region (in which T{sub e}>3.4 T{sub i} at ionospheric heights) caused by a rapid cooling the H{sup +} ions due to their resonant charge exchange with neutral hydrogen. Heat transfer from the top of the flux tube to the ionosphere is investigated using a hydrodynamic model for the ionosphere-plasmasphere coupling. Field-aligned currents, present in the topside ionosphere, are often accompanied by ion sound turbulence. The turbulence scatters electrons, increasing the total electron collision frequency through wave-particle effects. The influence of wave-particle interactions introduces an anomalous component to the total collision frequency, which modifies substantially the heat conduction coefficient of the plasma. As a result, the plasma is heated more intensely above than below this region of ion sound turbulence. 33 refs., 3 figs.

  7. Thermodynamic effect of the ion sound instability in the ionosphere

    NASA Technical Reports Server (NTRS)

    Khazanov, G. V.; Gombosi, T. I.; Gorbachev, O. A.; Trukhan, A. A.; Miller, R. H.

    1994-01-01

    During geomagnetic disturbances when the ring current interacts intensely with the plasmasphere, the plasma of this region undergoes a strong heating due to an ion cyclotron instability. This is followed by the transfer of heat along geomagnetic field lines from the heating region to the ionosphere. One of the results of this process is the formation of non-isothermal region (in which T(sub e) greater than 3.4 T(sub i) at ionospheric heights) caused by a rapid cooling the H(+) ions due to their resonant charge exchange with neutral hydrogen. Heat transfer from the top of the flux tube to the ionosphere is investigated using a hydrodynamic model for the ionosphere-plasmasphere coupling. Field-aligned currents, present in the topside ionosphere, are often accompanied by ion sound turbulence. The turbulence scatters electrons, increasing the total electron collision frequency through wave-particle effects. The influence of wave-particle interactions introduces an anomalous component to the total collision frequency, which modifies substantially the heat conduction coefficient of the plasma. As a result, the plasma is heated more intensely above than below this region of ion sound turbulence.

  8. Sound waves in multifractional liquids with bubbles

    NASA Astrophysics Data System (ADS)

    Gubaidullin, D. A.; Gafiyatov, R. N.

    2017-01-01

    The propagation of sound waves in multifractional mixtures of liquid with vapor–gas and gas bubbles of different sizes and different compositions with phase transitions is studied. The dispersed phase consists of N+M fractions having various gases in bubbles and different in the bubbles radii. Phase transitions accounted for N fractions. The total bubble volume concentration is small (less than 1%). The dispersion relation is derived and dispersion curves is built. The evolution of the weak pulsed perturbations of the pressure in this mixture was calculated numerically.

  9. Standing Sound Waves in Air with DataStudio

    ERIC Educational Resources Information Center

    Kraftmakher, Yaakov

    2010-01-01

    Two experiments related to standing sound waves in air are adapted for using the ScienceWorkshop data-acquisition system with the DataStudio software from PASCO scientific. First, the standing waves are created by reflection from a plane reflector. The distribution of the sound pressure along the standing wave is measured. Second, the resonance…

  10. Rayleigh scattering of a spherical sound wave.

    PubMed

    Godin, Oleg A

    2013-02-01

    Acoustic Green's functions for a homogeneous medium with an embedded spherical obstacle arise in analyses of scattering by objects on or near an interface, radiation by finite sources, sound attenuation in and scattering from clouds of suspended particles, etc. An exact solution of the problem of diffraction of a monochromatic spherical sound wave on a sphere is given by an infinite series involving products of Bessel functions and Legendre polynomials. In this paper, a simple, closed-form solution is obtained for scattering by a sphere with a radius that is small compared to the wavelength. Soft, hard, impedance, and fluid obstacles are considered. The solution is valid for arbitrary positions of the source and receiver relative to the scatterer. Low-frequency scattering is shown to be rather sensitive to boundary conditions on the surface of the obstacle. Low-frequency asymptotics of the scattered acoustic field are extended to transient incident waves. The asymptotic expansions admit an intuitive interpretation in terms of image sources and reduce to classical results in appropriate limiting cases.

  11. Sounding of the Ion Energization Region: Resolving Ambiguities

    NASA Technical Reports Server (NTRS)

    LaBelle, James

    2003-01-01

    Dartmouth College provided a single-channel high-frequency wave receiver to the Sounding of the Ion Energization Region: Resolving Ambiguities (SIERRA) rocket experiment launched from Poker Flat, Alaska, in January 2002. The receiver used signals from booms, probes, preamplifiers, and differential amplifiers provided by Cornell University coinvestigators. Output was to a dedicated 5 MHz telemetry link provided by WFF, with a small amount of additional Pulse Code Modulation (PCM) telemetry required for the receiver gain information. We also performed preliminary analysis of the data. The work completed is outlined below, in chronological order.

  12. Spin current-induced by a sound wave.

    PubMed

    Lyapilin, Igor I

    2013-04-01

    The interaction of conduction electrons with a longitudinal sound wave propagating in a crystal in a constant magnetic field is investigated. It is shown that the transverse spin current arises when the longitudinal sound wave propagation through the system. The average power absorbed by the spin subsystem of the conduction electrons and the spin-Hall conductivity have a resonant character.

  13. Visualization of Sound Waves Using Regularly Spaced Soap Films

    ERIC Educational Resources Information Center

    Elias, F.; Hutzler, S.; Ferreira, M. S.

    2007-01-01

    We describe a novel demonstration experiment for the visualization and measurement of standing sound waves in a tube. The tube is filled with equally spaced soap films whose thickness varies in response to the amplitude of the sound wave. The thickness variations are made visible based on optical interference. The distance between two antinodes is…

  14. Ion Bernstein wave heating research

    SciTech Connect

    Ono, Masayuki

    1992-03-01

    Ion Bernstein wave heating (IBWH) utilizes the ion Bernstein wave (IBW), a hot plasma wave, to carry the radio frequency (rf) power to heat tokamak reactor core. Earlier wave accessibility studies have shown that this finite-Larmor-radius (FLR) mode should penetrate into a hot dense reactor plasma core without significant attenuation. Moreover, the IBW`s low phase velocity ({omega}/k{sub {perpendicular}} {approx} V{sub Ti} {much_lt} V{sub {alpha}}) greatly reduces the otherwise serious wave absorption by the 3.5 MeV fusion {alpha}-particles. In addition, the property of IBW`s that k{sub {perpendicular}} {rho}{sub i} {approx} 1 makes localized bulk ion heating possible at the ion cyclotron harmonic layers. Such bulk ion heating can prove useful in optimizing fusion reactivity. In another vein, with proper selection of parameters, IBW`s can be made subject to strong localized electron Landau damping near the major ion cyclotron harmonic resonance layers. This property can be useful, for example, for rf current drive in the reactor plasma core. This paper discusses this research.

  15. Ion Bernstein wave heating research

    SciTech Connect

    Ono, Masayuki.

    1992-03-01

    Ion Bernstein wave heating (IBWH) utilizes the ion Bernstein wave (IBW), a hot plasma wave, to carry the radio frequency (rf) power to heat tokamak reactor core. Earlier wave accessibility studies have shown that this finite-Larmor-radius (FLR) mode should penetrate into a hot dense reactor plasma core without significant attenuation. Moreover, the IBW's low phase velocity ({omega}/k{sub {perpendicular}} {approx} V{sub Ti} {much lt} V{sub {alpha}}) greatly reduces the otherwise serious wave absorption by the 3.5 MeV fusion {alpha}-particles. In addition, the property of IBW's that k{sub {perpendicular}} {rho}{sub i} {approx} 1 makes localized bulk ion heating possible at the ion cyclotron harmonic layers. Such bulk ion heating can prove useful in optimizing fusion reactivity. In another vein, with proper selection of parameters, IBW's can be made subject to strong localized electron Landau damping near the major ion cyclotron harmonic resonance layers. This property can be useful, for example, for rf current drive in the reactor plasma core. This paper discusses this research.

  16. Spatial Statistics of Deep-Water Ambient Noise; Dispersion Relations for Sound Waves and Shear Waves

    DTIC Science & Technology

    2015-09-30

    Environmental and system data will also be depth-profiled, including temperature , salinity, pressure and (directly measured) sound speed, along...configurations, and an environmental sensor package [Conductivity- Temperature - Depth sensor (CTD) plus sound speed sensor (SVX)]. The system is untethered...Dispersion Relations for Sound Waves and Shear Waves Michael J. Buckingham Marine Physical Laboratory, Scripps Institution of Oceanography University

  17. [Pneumonia, when sound waves mix things up].

    PubMed

    Wachters, C; Hildebrand, M

    2011-01-01

    A 29-year old man is admitted in our hospital for a dry cough which appeared a few weeks earlier and is now associated with a breath depending thoracic pain. As an engineer, he is realizing a thesis about the sound waves produced by coughing and is therefore frequently exposed to patients with various pulmonary infections. The chest X-ray, presents predominant pulmonary infiltrates on the periphery of the upper fields of the lungs. Blood analysis revealed a hypereosinophilia of 4.650/microl. The various bacteriological, parasitic and viral investigation tests are negative. The bronchioalveolar washing reveals more than 50% eosinophils. Exclusive pulmonary impairment and lack of autoantibody moved us to the diagnosis of chronic eosinophilic pneumonia (or Carrington syndrome). Corticosteroids were started at the dosis of 0,5 mg/kg of methyl-prednisolone. Clinical and biological features improved amazingly within 48 hours. This case report illustrates the overlap between the chronic eosinophilic pneumonia and the Churg-Strauss desease who can be considered as variants of the hypereosinophilic syndrome (HES). Therefore, the use of anti-interleukin-5 antibodies, already used in the SHE and Churg-Strauss syndrome, might be useful in this case.

  18. A mechanism study of sound wave-trapping barriers.

    PubMed

    Yang, Cheng; Pan, Jie; Cheng, Li

    2013-09-01

    The performance of a sound barrier is usually degraded if a large reflecting surface is placed on the source side. A wave-trapping barrier (WTB), with its inner surface covered by wedge-shaped structures, has been proposed to confine waves within the area between the barrier and the reflecting surface, and thus improve the performance. In this paper, the deterioration in performance of a conventional sound barrier due to the reflecting surface is first explained in terms of the resonance effect of the trapped modes. At each resonance frequency, a strong and mode-controlled sound field is generated by the noise source both within and in the vicinity outside the region bounded by the sound barrier and the reflecting surface. It is found that the peak sound pressures in the barrier's shadow zone, which correspond to the minimum values in the barrier's insertion loss, are largely determined by the resonance frequencies and by the shapes and losses of the trapped modes. These peak pressures usually result in high sound intensity component impinging normal to the barrier surface near the top. The WTB can alter the sound wave diffraction at the top of the barrier if the wavelengths of the sound wave are comparable or smaller than the dimensions of the wedge. In this case, the modified barrier profile is capable of re-organizing the pressure distribution within the bounded domain and altering the acoustic properties near the top of the sound barrier.

  19. Synthesis of very small diameter silica nanofibers using sound waves.

    PubMed

    Datskos, Panos; Chen, Jihua; Sharma, Jaswinder

    2014-07-14

    Silica nanofibers of an average diameter ≈30 nm and length ≈100 μm have been synthesized using an unprecedented strategy: sound waves. A new phenomenon, spinning off the nanofibers at silica rod tips, is also observed.

  20. Demonstrating Sound Wave Propagation with Candle Flame and Loudspeaker

    ERIC Educational Resources Information Center

    Hrepic, Zdeslav; Nettles, Corey; Bonilla, Chelsea

    2013-01-01

    The motion of a candle flame in front of a loudspeaker has been suggested as a productive demonstration of the longitudinal wave nature of sound. The demonstration has been used also as a research tool to investigate students' understanding about sound. The underpinning of both applications is the expectation of a horizontal, back-and-forth…

  1. Analyzing Sound Waves Produced by Musical Notes & Chords.

    ERIC Educational Resources Information Center

    Cassidy, Michael

    This project description is designed to show how graphing calculators and calculator-based laboratories (CBL) can be used to explore topics in the physics of sound. The activities address topics such as sound waves, musical notes, and chords. Teaching notes, calculator instructions, and blackline masters are included. (MM)

  2. Air-borne sound generated by sea waves.

    PubMed

    Bolin, Karl; Åbom, Mats

    2010-05-01

    This paper describes a semi-empiric model and measurements of air-borne sound generated by breaking sea waves. Measurements have been performed at the Baltic Sea. Shores with different slopes and sediment types have been investigated. Results showed that the sound pressure level increased from 60 dB at 0.4 m wave height to 78 dB at 2.0 m wave height. The 1/3 octave spectrum was dependent on the surf type. A scaling model based on the dissipated wave power and a surf similarity parameter is proposed and compared to measurements. The predictions show satisfactory agreement to the measurements.

  3. Nonlinear decay of electromagnetic ion cyclotron waves in the magnetosphere

    SciTech Connect

    Gomberoff, L.; Gratton, F.T.; Gnavi, G.

    1995-02-01

    The authors study the parametric decays of left-hand polarized electromagnetic ion cyclotron waves, propagating parallel to the external magnetic field, in the magnetosphere. They show that the presence of He{sup +} ions and a mixed population of thermal and hot protons give rise to new wave couplings. These couplings lead to a number of new instabilities. Some of the instabilities involve sound waves carried mainly by the He{sup +} ions, which can be very efficient in heating up the bulk of the He{sup +} ions via Landau damping. Other instabilities involve the branch of the left-hand polarized electromagnetic ion cyclotron waves which has a resonance at the He{sup +} ion gyrofrequency. These instabilities can also play a role in the energy transfer from the pump wave to the He{sup +} ions through resonance absorption, preferably in the direction perpendicular to the external magnetic field. The new couplings give rise to several types of parametric instabilities such as ordinary decay instabilities, beat wave instabilities, and modulational instabilities. There are also couplings where the pump wave decays into the two electromagnetic sideband waves. 42 refs., 10 figs.

  4. Time dependent wave envelope finite difference analysis of sound propagation

    NASA Technical Reports Server (NTRS)

    Baumeister, K. J.

    1984-01-01

    A transient finite difference wave envelope formulation is presented for sound propagation, without steady flow. Before the finite difference equations are formulated, the governing wave equation is first transformed to a form whose solution tends not to oscillate along the propagation direction. This transformation reduces the required number of grid points by an order of magnitude. Physically, the transformed pressure represents the amplitude of the conventional sound wave. The derivation for the wave envelope transient wave equation and appropriate boundary conditions are presented as well as the difference equations and stability requirements. To illustrate the method, example solutions are presented for sound propagation in a straight hard wall duct and in a two dimensional straight soft wall duct. The numerical results are in good agreement with exact analytical results.

  5. Scattering of sound waves by a compressible vortex

    NASA Technical Reports Server (NTRS)

    Colonius, Tim; Lele, Sanjiva K.; Moin, Parviz

    1991-01-01

    Scattering of plane sound waves by a compressible vortex is investigated by direct computation of the two-dimensional Navier-Stokes equations. Nonreflecting boundary conditions are utilized, and their accuracy is established by comparing results on different sized domains. Scattered waves are directly measured from the computations. The resulting amplitude and directivity pattern of the scattered waves is discussed, and compared to various theoretical predictions. For compact vortices (zero circulation), the scattered waves directly computed are in good agreement with predictions based on an acoustic analogy. Strong scattering at about + or - 30 degrees from the direction of incident wave propagation is observed. Back scattering is an order of magnitude smaller than forward scattering. For vortices with finite circulation refraction of the sound by the mean flow field outside the vortex core is found to be important in determining the amplitude and directivity of the scattered wave field.

  6. Iron sound velocities in shock wave experiments

    SciTech Connect

    Holmes, N C; Nguyen, J H

    1999-08-20

    We have performed a series of sound velocity measurements in iron at earth's core pressures. Experiments were carried out at shock pressures as high as 400 GPa, with particular emphasis on the pressure range between 175 GPa and 275 GPa. The measured sound velocities of iron at elevated pressures exhibit a single discontinuity near 250 GPa, corresponding to the vanishing of shear strength as the iron melts. A second discontinuity reported by Brown and McQueen in their previous iron sound velocity studies was not observed in our study. Our results are consistent with their data otherwise. Experimental details and error propagation techniques essential to determining the melting point will also be discussed.

  7. Diffusion of Sound Waves in a Turbulent Atmosphere

    NASA Technical Reports Server (NTRS)

    Lyon, Richard H.

    1960-01-01

    The directional and frequency diffusion of a plane monochromatic 2 sound wave in statistically homogeneous, isotropic, and stationary turbulence is analyzed theoretically. The treatment is based on the diffusion equation for the energy density of sound waves, using the scattering cross section derived by Kraichnan for the type of turbulence assumed here. A form for the frequency-wave number spectrum of the turbulence is adopted which contains the pertinent parameters of the flow and is adapted to ease of calculation. A new approach to the evaluation of the characteristic period of the flow is suggested. This spectrum is then related to the scattering cross section. Finally, a diffusion equation is derived as a small-angle scattering approximation to the rigorous transport equation. The rate of spread of the incident wave in frequency and direction is calculated, as well as the power spectrum and autocorrelation for the wave.

  8. Monograph on propagation of sound waves in curved ducts

    NASA Technical Reports Server (NTRS)

    Rostafinski, Wojciech

    1991-01-01

    After reviewing and evaluating the existing material on sound propagation in curved ducts without flow, it seems strange that, except for Lord Rayleigh in 1878, no book on acoustics has treated the case of wave motion in bends. This monograph reviews the available analytical and experimental material, nearly 30 papers published on this subject so far, and concisely summarizes what has been learned about the motion of sound in hard-wall and acoustically lined cylindrical bends.

  9. Chaotic ion motion in magnetosonic plasma waves

    NASA Technical Reports Server (NTRS)

    Varvoglis, H.

    1984-01-01

    The motion of test ions in a magnetosonic plasma wave is considered, and the 'stochasticity threshold' of the wave's amplitude for the onset of chaotic motion is estimated. It is shown that for wave amplitudes above the stochasticity threshold, the evolution of an ion distribution can be described by a diffusion equation with a diffusion coefficient D approximately equal to 1/v. Possible applications of this process to ion acceleration in flares and ion beam thermalization are discussed.

  10. Shallow water sound propagation with surface waves.

    PubMed

    Tindle, Chris T; Deane, Grant B

    2005-05-01

    The theory of wavefront modeling in underwater acoustics is extended to allow rapid range dependence of the boundaries such as occurs in shallow water with surface waves. The theory allows for multiple reflections at surface and bottom as well as focusing and defocusing due to reflection from surface waves. The phase and amplitude of the field are calculated directly and used to model pulse propagation in the time domain. Pulse waveforms are obtained directly for all wavefront arrivals including both insonified and shadow regions near caustics. Calculated waveforms agree well with a reference solution and data obtained in a near-shore shallow water experiment with surface waves over a sloping bottom.

  11. Scattering of coherent sound waves by atmospheric turbulence

    NASA Technical Reports Server (NTRS)

    Chow, P. L.; Liu, C. H.; Maestrello, L.

    1975-01-01

    An analytical study of the propagation of coherent sound waves through an atmosphere containing both mean and fluctuating flow variables is presented. The general flow problem is formulated as a time-dependent wave propagation in a half-space containing the turbulent medium. The coherent acoustic waves are analyzed by a smoothing technique, assuming that mean flow variables vary with the height only. The general equations for the coherent waves are derived, and then applied to two special cases, corresponding to uniform and shear mean flow, respectively. The results show that mean shear and turbulence introduce pronounced effects on the propagation of coherent acoustic disturbances.

  12. Attenuation of sound waves in drill strings

    SciTech Connect

    Drumheller, D.S. )

    1993-10-01

    During drilling of deep wells, digital data are often transmitted from sensors located near the drill bit to the surface. Development of a new communication system with increased data capacity is of paramount importance to the drilling industry. Since steel drill strings are used, transmission of these data by elastic carrier waves traveling within the drill pipe is possible, but the potential communication range is uncertain. The problem is complicated by the presence of heavy-threaded tool joints every 10 m, which form a periodic structure and produce classical patterns of passbands and stop bands in the wave spectra. In this article, field measurements of the attenuation characteristics of a drill string in the Long Valley Scientific Well in Mammoth Lakes, California are presented. Wave propagation distances approach 2 km. A theoretical model is discussed which predicts the location, width, and attenuation of the passbands. Mode conversion between extensional and bending waves, and spurious reflections due to deviations in the periodic spacings of the tool joints are believed to be the sources of this attenuation. It is estimated that attenuation levels can be dramatically reduced by rearranging the individual pipes in the drill string according to length. 7 refs., 20 figs., 4 tabs.

  13. Non-contact sound speed measurement by optical probing of beam deflection due to sound wave.

    PubMed

    Jung, Sung Soo; Kim, Yong Tae; Pu, Yu Cheon; Kim, Min Gon; Kim, Ho Chul

    2006-01-01

    We report a non-contact and non-invasive method of sound speed measurement by optical probing of deflected laser beam due to normally incident degenerated shock wave. In this study the shock wave from an exploding wire was degenerated to an ordinary sound wave at the distance exceeding 0.23 m. Temporal resolution of the deflected beam signal was improved by passing through an adequate electronic high-pass filter, as a result we obtained a better temporal resolution than that of the acoustic pressure detection by PZT transducer in terms of rising time. The spatial resolution was improved by passing the refracted beam signal into the edge of focusing lens to make a larger deflection angle. Sound speed was calculated by monitoring the time of flight of transient deflected signal at the predetermined position. Sound speed has been measured in air, distilled water and acryl, agreed well with the published values. The sound speed measured in the solution of glycerin, magnesium sulfate (MgSO4), and dimethylformamide with various mole fractions also agrees within 3% of relative error with those measured in the present work by ultrasonic pulse echo method. The results suggest that the method proposed is to be reliable and reproducible.

  14. Understanding and Affecting Student Reasoning about Sound Waves.

    ERIC Educational Resources Information Center

    Wittmann, Michael C.; Steinberg, Richard N.; Redish, Edward F.

    2003-01-01

    Explains the design and development of curriculum materials that ask students to think about physics from a different view. These group-learning classroom materials specifically aim to bring about improvement of student understanding of sound waves. (Contains 29 references.) (Author/SOE)

  15. Ion Bernstein wave heating research

    NASA Astrophysics Data System (ADS)

    Ono, Masayuki

    1993-02-01

    Ion Bernstein wave heating (IBWH) utilizes the ion Bernstein wave (IBW), a hot plasma wave, to carry the radio frequency (rf) power to heat the tokamak reactor core. Earlier wave accessibility studies have shown that this finite-Larmor-radius (FLR) mode should penetrate into a hot dense reactor plasma core without significant attenuation. Moreover, the IBW's low perpendicular phase velocity (ω/k⊥≊VTi≪Vα) greatly reduces the otherwise serious wave absorption by the 3.5 MeV fusion α particles. In addition, the property of IBW's that k⊥ρi≊1 makes localized bulk ion heating possible at the ion cyclotron harmonic layers. Such bulk ion heating can prove useful in optimizing fusion reactivity. In another vein, with proper selection of parameters, IBW's can be made subject to strong localized electron Landau damping near the major ion cyclotron harmonic resonance layers. This property can be useful, for example, for rf current drive in the reactor plasma core. IBW's can be excited with loop antennas or with a lower-hybrid-like waveguide launcher at the plasma edge, the latter structure being one that is especially compatible with reactor application. In either case, the mode at the plasma edge is an electron plasma wave (EPW). Deeper in the plasma, the EPW is mode transformed into an IBW. Such launching and mode transformation of IBW's were first demonstrated in experiments in the Advanced Concepts Torus-1 (ACT-1) [Phys. Rev. Lett. 45, 1105 (1980)] plasma torus and in particle simulation calculations. These and other aspects of IBW heating physics have been investigated through a number of experiments performed on ACT-1, the Japanese Institute of Plasma Physics Tokamak II-Upgrade (JIPPTII-U) [Phys. Rev. Lett. 54, 2339 (1985)], the Tokyo University Non-Circular Tokamak (TNT) [Nucl. Fusion 26, 1097 (1986)], the Princeton Large Tokamak (PLT) [Phys. Rev. Lett. 60, 294 (1988)], and Alcator-C [Phys. Rev. Lett. 60, 298 (1988)]. In these experiments both linear and

  16. Sound

    NASA Astrophysics Data System (ADS)

    Capstick, J. W.

    2013-01-01

    1. The nature of sound; 2. Elasticity and vibrations; 3. Transverse waves; 4. Longitudinal waves; 5. Velocity of longitudinal waves; 6. Reflection and refraction. Doppler's principle; 7. Interference. Beats. Combination tones; 8. Resonance and forced vibrations; 9. Quality of musical notes; 10. Organ pipes; 11. Rods. Plates. Bells; 12. Acoustical measurements; 13. The phonograph, microphone and telephone; 14. Consonance; 15. Definition of intervals. Scales. Temperament; 16. Musical instruments; 17. Application of acoustical principles to military purposes; Questions; Answers to questions; Index.

  17. Multiple slow waves in metaporous layers for broadband sound absorption

    NASA Astrophysics Data System (ADS)

    Yang, Jieun; Lee, Joong Seok; Kim, Yoon Young

    2017-01-01

    Sound absorption for a broad frequency range requires sound dissipation. The mechanics of acoustic metamaterials for non-dissipative applications has been extensively studied, but sound absorption using dissipative porous metamaterials has been less explored because of the complexity resulting from the coupling of its dissipative mechanism and metamaterial behavior. We investigated broadband sound absorption by engineering dissipative metaporous layers, which absorb sound by the mechanism of multiple slow waves, and combined local and global resonance phenomena. A set of rigid partitions of varying lengths was elaborately inserted in a hard-backed porous layer of a finite thickness. An effective medium theory was used to explain the physics involved; high performance at a low-frequency range was found to be mainly due to the formation of global resonances caused by multiple slow waves over the thickness of the metaporous layer, while enhancement at a high-frequency range was attributed to the combined effects of the global resonances and the local resonances directly related to the sizes of the inserted partitions.

  18. Response of thermal ions to electromagnetic ion cyclotron waves

    NASA Technical Reports Server (NTRS)

    Anderson, B. J.; Fuselier, S. A.

    1994-01-01

    Electromagnetic ion cyclotron waves generated by 10 - 50 keV protons in the Earth's equatorial magnetosphere will interact with the ambient low-energy ions also found in this region. We examine H(+) and He(+) distribution functions from approx. equals 1 to 160 eV using the Hot Plasma Composition Experiment instrument on AMPTE/CCE to investigate the thermal ion response to the waves. A total of 48 intervals were chosen on the basis of electromagnetic ion cyclotron (EMIC) wave activity: 24 with prevalent EMIC waves and 24 with no EMIC waves observed on the orbit. There is a close correlation between EMIC waves and perpendicular heated ion distributions. For protons the perpendicular temperature increase is modest, about 5 eV, and is always observed at 90 deg pitch angles. This is consistent with a nonresonant interaction near the equator. By contrast, He(+) temperatures during EMIC wave events averaged 35 eV and sometimes exceeded 100 eV, indicating stronger interaction with the waves. Furthermore, heated He(+) ions have X-type distributions with maximum fluxes occurring at pitch angles intermediate between field-aligned and perpendicular directions. The X-type He(+) distributions are consistent with a gyroresonant interaction off the equator. The concentration of He(+) relative to H(+) is found to correlate with EMIC wave activity, but it is suggested that the preferential heating of He(+) accounts for the apparent increase in relative He(+) concentration by increasing the proportion of He(+) detected by the ion instrument.

  19. Response of thermal ions to electromagnetic ion cyclotron waves

    NASA Astrophysics Data System (ADS)

    Anderson, B. J.; Fuselier, S. A.

    1994-10-01

    Electromagnetic ion cyclotron waves generated by 10 - 50 keV protons in the Earth's equatorial magnetosphere will interact with the ambient low-energy ions also found in this region. We examine H(+) and He(+) distribution functions from approx. equals 1 to 160 eV using the Hot Plasma Composition Experiment instrument on AMPTE/CCE to investigate the thermal ion response to the waves. A total of 48 intervals were chosen on the basis of electromagnetic ion cyclotron (EMIC) wave activity: 24 with prevalent EMIC waves and 24 with no EMIC waves observed on the orbit. There is a close correlation between EMIC waves and perpendicular heated ion distributions. For protons the perpendicular temperature increase is modest, about 5 eV, and is always observed at 90 deg pitch angles. This is consistent with a nonresonant interaction near the equator. By contrast, He(+) temperatures during EMIC wave events averaged 35 eV and sometimes exceeded 100 eV, indicating stronger interaction with the waves. Furthermore, heated He(+) ions have X-type distributions with maximum fluxes occurring at pitch angles intermediate between field-aligned and perpendicular directions. The X-type He(+) distributions are consistent with a gyroresonant interaction off the equator. The concentration of He(+) relative to H(+) is found to correlate with EMIC wave activity, but it is suggested that the preferential heating of He(+) accounts for the apparent increase in relative He(+) concentration by increasing the proportion of He(+) detected by the ion instrument.

  20. Simulation of Sound Waves Using the Lattice Boltzmann Method for Fluid Flow: Benchmark Cases for Outdoor Sound Propagation

    PubMed Central

    Salomons, Erik M.; Lohman, Walter J. A.; Zhou, Han

    2016-01-01

    Propagation of sound waves in air can be considered as a special case of fluid dynamics. Consequently, the lattice Boltzmann method (LBM) for fluid flow can be used for simulating sound propagation. In this article application of the LBM to sound propagation is illustrated for various cases: free-field propagation, propagation over porous and non-porous ground, propagation over a noise barrier, and propagation in an atmosphere with wind. LBM results are compared with solutions of the equations of acoustics. It is found that the LBM works well for sound waves, but dissipation of sound waves with the LBM is generally much larger than real dissipation of sound waves in air. To circumvent this problem it is proposed here to use the LBM for assessing the excess sound level, i.e. the difference between the sound level and the free-field sound level. The effect of dissipation on the excess sound level is much smaller than the effect on the sound level, so the LBM can be used to estimate the excess sound level for a non-dissipative atmosphere, which is a useful quantity in atmospheric acoustics. To reduce dissipation in an LBM simulation two approaches are considered: i) reduction of the kinematic viscosity and ii) reduction of the lattice spacing. PMID:26789631

  1. Simulation of Sound Waves Using the Lattice Boltzmann Method for Fluid Flow: Benchmark Cases for Outdoor Sound Propagation.

    PubMed

    Salomons, Erik M; Lohman, Walter J A; Zhou, Han

    2016-01-01

    Propagation of sound waves in air can be considered as a special case of fluid dynamics. Consequently, the lattice Boltzmann method (LBM) for fluid flow can be used for simulating sound propagation. In this article application of the LBM to sound propagation is illustrated for various cases: free-field propagation, propagation over porous and non-porous ground, propagation over a noise barrier, and propagation in an atmosphere with wind. LBM results are compared with solutions of the equations of acoustics. It is found that the LBM works well for sound waves, but dissipation of sound waves with the LBM is generally much larger than real dissipation of sound waves in air. To circumvent this problem it is proposed here to use the LBM for assessing the excess sound level, i.e. the difference between the sound level and the free-field sound level. The effect of dissipation on the excess sound level is much smaller than the effect on the sound level, so the LBM can be used to estimate the excess sound level for a non-dissipative atmosphere, which is a useful quantity in atmospheric acoustics. To reduce dissipation in an LBM simulation two approaches are considered: i) reduction of the kinematic viscosity and ii) reduction of the lattice spacing.

  2. Determination of ocean surface wave shape from forward scattered sound.

    PubMed

    Walstead, Sean P; Deane, Grant B

    2016-08-01

    Forward scattered sound from the ocean surface is inverted for wave shape during three periods: low wind, mix of wind and swell, and stormy. Derived wave profiles are spatially limited to a Fresnel region at or near the nominal surface specular reflection point. In some cases, the surface wave profiles exhibit unrealistic temporal and spatial properties. To remedy this, the spatial gradient of inverted waves is constrained to a maximum slope of 0.88. Under this global constraint, only surface waves during low wind conditions result in a modeled surface multipath that accurately matches data. The power spectral density of the inverted surface wave field saturates around a frequency of 8 Hz while upward looking SONAR saturates at 1 Hz. Each shows a high frequency spectral slope of -4 that is in agreement with various empirical ocean wave spectra. The improved high frequency resolution provided by the scattering inversion indicates that it is possible to remotely gain information about high frequency components of ocean waves. The inability of the inversion algorithm to determine physically realistic surface waves in periods of high wind indicates that bubbles and out of plane scattering become important in those operating scenarios.

  3. Effect of Intense Sound Waves on a Stationary Gas Flame

    NASA Technical Reports Server (NTRS)

    Hahnemann, H; Ehret, L

    1950-01-01

    Intense sound waves with a resonant frequency of 5000 cycles per second were imposed on a stationary propane-air flame issuing from a nozzle. In addition to a slight increase of the flame velocity, a fundamental change both in the shape of the burning zone and in the flow pattern could be observed. An attempt is made to explain the origin of the variations in the flame configuration on the basis of transition at the nozzle from jet flow to potential flow.

  4. Cylindrical sound wave generated by shock-vortex interaction

    NASA Technical Reports Server (NTRS)

    Ribner, H. S.

    1985-01-01

    The passage of a columnar vortex broadside through a shock is investigated. This has been suggested as a crude, but deterministic, model of the generation of 'shock noise' by the turbulence in supersonic jets. The vortex is decomposed by Fourier transform into plane sinusoidal shear waves disposed with radial symmetry. The plane sound waves produced by each shear wave/shock interaction are recombined in the Fourier integral. The waves possess an envelope that is essentially a growing cylindrical sound wave centered at the transmitted vortex. The pressure jump across the nominal radius R = ct attenuates with time as 1/(square root of R) and varies around the arc in an antisymmetric fashion resembling a quadrupole field. Very good agreement, except near the shock, is found with the antisymmetric component of reported interferometric measurements in a shock tube. Beyond the front r approximately equals R is a precursor of opposite sign, that decays like 1/R, generated by the 1/r potential flow around the vortex core. The present work is essentially an extension and update of an early approximate study at M = 1.25. It covers the range (R/core radius) = 10, 100, 1000, and 10,000 for M = 1.25 and (in part) for M = 1.29 and, for fixed (R/core radius) = 1000, the range M = 1.01 to infinity.

  5. Laboratory measurements of the effect of internal waves on sound propagation

    NASA Astrophysics Data System (ADS)

    Zhang, Likun; Swinney, Harry L.; Lin, Ying-Tsong

    2016-11-01

    The fidelity of acoustic signals used in communication and imaging in the oceans is limited by density fluctuations arising from many sources, particularly from internal waves. We present results from laboratory experiments on sound propagation through an internal wave field produced by a wave generator consisting of multiple oscillating plates. The fluid density as a function of height is measured and used to determine the sound speed as a function of the height. Sound pulses from a transducer propagate through the fluctuating stratified density field and are detected to determine sound refraction, pulse arrival time, and sound signal distortion. The results are compared with sound ray model and numerical models of underwater sound propagation. The laboratory experiments can explore the parameter dependence by varying the fluid density profile, the sound pulse signal, and the internal wave amplitude and frequency. The results lead to a better understanding of sound propagation through and scattered by internal waves.

  6. Investigation of an ion-ion hybrid Alfven wave resonator

    SciTech Connect

    Vincena, S. T.; Farmer, W. A.; Maggs, J. E.; Morales, G. J.

    2013-01-15

    A theoretical and experimental investigation is made of a wave resonator based on the concept of wave reflection along the confinement magnetic field at a spatial location where the wave frequency matches the local value of the ion-ion hybrid frequency. Such a situation can be realized by shear Alfven waves in a magnetized plasma with two ion species because this mode has zero parallel group velocity and experiences a cut-off at the ion-ion hybrid frequency. Since the ion-ion hybrid frequency is proportional to the magnetic field, it is expected that a magnetic well configuration in a two-ion plasma can result in an Alfven wave resonator. Such a concept has been proposed in various space plasma studies and could have relevance to mirror and tokamak fusion devices. This study demonstrates such a resonator in a controlled laboratory experiment using a H{sup +}-He{sup +} mixture. The resonator response is investigated by launching monochromatic waves and impulses from a magnetic loop antenna. The observed frequency spectra are found to agree with predictions of a theoretical model of trapped eigenmodes.

  7. Global Simulation of Electromagnetic Ion Cyclotron Waves

    NASA Technical Reports Server (NTRS)

    Khazanov, G. V.; Gamayunov, K.; Gallagher, D. L.; Kozyra, J. U.

    2007-01-01

    It is well known that the effects of electromagnetic ion cyclotron (EMIC) waves on ring current (RC) ion and radiation belt (RB) electron dynamics strongly depend on such particle/wave characteristics as the phase-space distribution function, frequency, wave-normal angle, wave energy, and the form of wave spectral energy density. The consequence is that accurate modeling of EMIC waves and RC particles requires robust inclusion of the interdependent dynamics of wave growth/damping, wave propagation, and particles. Such a self-consistent model is being progressively developed by Khazanov et al. [2002 - 2007]. This model is based on a system of coupled kinetic equations for the RC and EMIC wave power spectral density along with the ray tracing equations. We will discuss the recent progress in understanding EMIC waves formation mechanisms in the inner magnetosphere. This problem remains unsettled in spite of many years of experimental and theoretical studies. Modern satellite observations by CRRES, Polar and Cluster still do not reveal the whole picture experimentally since they do not stay long enough in the generation region to give a full account of all the spatio-temporal structure of EMIC waves. The complete self-consistent theory taking into account all factors significant for EMIC waves generation remains to be developed. Several mechanisms are discussed with respect to formation of EMIC waves, among them are nonlinear modification of the ionospheric reflection by precipitating energetic protons, modulation of ion-cyclotron instability by long-period (Pc3/4) pulsations, reflection of waves from layers of heavy-ion gyroresonances, and nonlinearities of wave generation process. We show that each of these mechanisms have their attractive features and explains certain part experimental data but any of them, if taken alone, meets some difficulties when compared to observations. We conclude that development of a refined nonlinear theory and further correlated analysis

  8. Global Simulation of Electromagnetic Ion Cyclotron Waves

    NASA Technical Reports Server (NTRS)

    Khazanov, George V.; Gallagher, D. L.; Kozyra, J. U.

    2007-01-01

    It is very well known that the effects of electromagnetic ion cyclotron (EMIC) waves on ring current (RC) ion and radiation belt (RB) electron dynamics strongly depend on such particle/wave characteristics as the phase-space distribution function, frequency, wave-normal angle, wave energy, and the form of wave spectral energy density. The consequence is that accurate modeling of EMIC waves and RC particles requires robust inclusion of the interdependent dynamics of wave growth/damping, wave propagation, and particles. Such a self-consistent model is being progressively developed by Khazanov et al. This model is based on a system of coupled kinetic equations for the RC and EMIC wave power spectral density along with the ray tracing equations. We will discuss the recent progress in understanding EMIC waves formation mechanisms in the inner magnetosphere. This problem remains unsettled in spite of many years of experimental and theoretical studies. Modern satellite observations by CRRES, Polar and Cluster still do not reveal the whole picture experimentally since they do not stay long enough in the generation region to give a full account of all the spatio-temporal structure of EMIC waves. The complete self-consistent theory taking into account all factors significant for EMIC waves generation remains to be developed. Several mechanisms are discussed with respect to formation of EMIC waves, among them are nonlinear modification of the ionospheric reflection by precipitating energetic protons, modulation of ion-cyclotron instability by long-period (Pc3/4) pulsations, reflection of waves from layers of heavy-ion gyroresonances, and nonlinearities of wave generation process. We show that each of these mechanisms have their attractive features and explains certain part experimental data but any of them, if taken alone, meets some difficulties when compared to observations. We conclude that development of a refined nonlinear theory and further correlated analysis of modern

  9. Global Simulation of Electromagnetic Ion Cyclotron Waves

    NASA Astrophysics Data System (ADS)

    Khazanov, G. V.; Gamayunov, K. V.; Gallagher, D. L.; Kozyra, J. U.

    2007-12-01

    It is well known that the effects of electromagnetic ion cyclotron (EMIC) waves on ring current (RC) ion and radiation belt (RB) electron dynamics strongly depend on such particle/wave characteristics as the phase-space distribution function, frequency, wave-normal angle, wave energy, and the form of wave spectral energy density. The consequence is that accurate modeling of EMIC waves and RC particles requires robust inclusion of the interdependent dynamics of wave growth/damping, wave propagation, and particles. Such a self-consistent model is being progressively developed by Khazanov et al. [2002 - 2007]. This model is based on a system of coupled kinetic equations for the RC and EMIC wave power spectral density along with the ray tracing equations. We will discuss the recent progress in understanding EMIC waves formation mechanisms in the inner magnetosphere. This problem remains unsettled in spite of many years of experimental and theoretical studies. Modern satellite observations by CRRES, Polar and Cluster still do not reveal the whole picture experimentally since they do not stay long enough in the generation region to give a full account of all the spatio-temporal structure of EMIC waves. The complete self-consistent theory taking into account all factors significant for EMIC waves generation remains to be developed. Several mechanisms are discussed with respect to formation of EMIC waves, among them are nonlinear modification of the ionospheric reflection by precipitating energetic protons, modulation of ion-cyclotron instability by long-period (Pc3/4) pulsations, reflection of waves from layers of heavy-ion gyroresonances, and nonlinearities of wave generation process. We show that each of these mechanisms have their attractive features and explains certain part experimental data but any of them, if taken alone, meets some difficulties when compared to observations. We conclude that development of a refined nonlinear theory and further correlated analysis

  10. Elastic wave from fast heavy ion irradiation on solids

    NASA Astrophysics Data System (ADS)

    Kambara, T.; Kageyama, K.; Kanai, Y.; Kojima, T. M.; Nanai, Y.; Yoneda, A.; Yamazaki, Y.

    2002-06-01

    To study the time-dependent mechanical effects of fast heavy ion irradiations, we have irradiated various solids by a short-bunch beam of 95 MeV/u Ar ions and observed elastic waves generated in the bulk. The irradiated targets were square-shaped plates of poly-crystals of metals (Al and Cu), invar alloy, ceramic (Al 2O 3), fused silica (SiO 2) and single crystals of KC1 and LiF with a thickness of 10 mm. The beam was incident perpendicular to the surface and all ions were stopped in the target. Two piezo-electric ultrasonic sensors were attached to the surface of the target and detected the elastic waves. The elastic waveforms as well as the time structure and intensity of the beam bunch were recorded for each shot of a beam bunch. The sensor placed opposite to the beam spot recorded a clear waveform of the longitudinal wave across the material, except for the invar and fused silica targets. From its propagation time along with the sound velocity and the thickness of the target, the depth of the wave source was estimated. The result was compared with ion ranges calculated for these materials by TRIM code.

  11. Digitizing Sound: How Can Sound Waves be Turned into Ones and Zeros?

    NASA Astrophysics Data System (ADS)

    Vick, Matthew

    2010-10-01

    From MP3 players to cell phones to computer games, we're surrounded by a constant stream of ones and zeros. Do we really need to know how this technology works? While nobody can understand everything, digital technology is increasingly making our lives a collection of "black boxes" that we can use but have no idea how they work. Pursuing scientific literacy should propel us to open up a few of these metaphorical boxes. High school physics offers opportunities to connect the curriculum to sports, art, music, and electricity, but it also offers connections to computers and digital music. Learning activities about digitizing sounds offer wonderful opportunities for technology integration and student problem solving. I used this series of lessons in high school physics after teaching about waves and sound but before optics and total internal reflection so that the concepts could be further extended when learning about fiber optics.

  12. Evaluation of Interaction Between Fundamental Landscapes and Sounds in a District via Brain Wave

    NASA Astrophysics Data System (ADS)

    Okutani, Iwao; Takase, Tatsuo

    Interactions between regional landscape and sound are investigated in terms of subjects’ brain wave properties, i.e., α wave power spectrum and frequency fluctuation index of brain wave. The landscape samples consist of sea, buildings, crowds, trees, flowers, streamlet, vehicular traffic flow and residential area while the sound samples are made up of crowds sound, insect chirpings, rustling sound of leaves, wave sound, stream murmurings, bird chirpings and supersonic. It is revealed that (1) most of the best combinations of landscape and sound include natural landscape and sound whereas the worst combinations are associated with artificial environments, (2) best(worst) combinations determined via fluctuation index are composed of the landscape and sound which are evaluated as bests(worsts) at landscape only or sound only stimulus tests, (3) based on theα wave power spectrum, some of the best combinations include the landscapes and sounds which are evaluated low at the single stimulus tests and also some worst combinations include the stream murmuring sound or wave sound which are highly ranked at the sound only tests, (4) since supersonic appears in many worst combinations, it is likely to bring about unpleasant effects on human psychology.

  13. Fate of the initial state perturbations in heavy ion collisions. II. Glauber fluctuations and sounds

    SciTech Connect

    Staig, Pilar; Shuryak, Edward

    2011-09-15

    Heavy-ion collisions at the BNL Relativistic Heavy Ion Collider (RHIC) are well described by the (nearly ideal) hydrodynamics for average events. In the present paper we study initial state fluctuations appearing on an event-by-event basis and the propagation of perturbations induced by them. We found that (i) fluctuations of several of the lowest harmonics have comparable magnitudes and (ii) that at least all odd harmonics are correlated in phase, (iii) thus indicating the local nature of fluctuations. We argue that such local perturbations should be the source of the ''tiny bang,'' a pulse of sound propagating from it. We identify its two fundamental scales as (i) the ''sound horizon'' (analogous to the absolute ruler in cosmic microwave background and galaxy distributions) and (ii) the ''viscous horizon'' separating damped and undamped harmonics. We then qualitatively describe how one can determine them from the data and thus determine two fundamental parameters of the matter: the (average) speed of sound and viscosity. The rest of the paper explains how one can study mutual coherence of various harmonics. For that, one should go beyond the two-particle correlations to three (or more) particles. Mutual coherence is important for the picture of propagating sound waves.

  14. Finite-Difference Algorithms For Computing Sound Waves

    NASA Technical Reports Server (NTRS)

    Davis, Sanford

    1993-01-01

    Governing equations considered as matrix system. Method variant of method described in "Scheme for Finite-Difference Computations of Waves" (ARC-12970). Present method begins with matrix-vector formulation of fundamental equations, involving first-order partial derivatives of primitive variables with respect to space and time. Particular matrix formulation places time and spatial coordinates on equal footing, so governing equations considered as matrix system and treated as unit. Spatial and temporal discretizations not treated separately as in other finite-difference methods, instead treated together by linking spatial-grid interval and time step via common scale factor related to speed of sound.

  15. Xe/+/ -induced ion-cyclotron harmonic waves

    NASA Astrophysics Data System (ADS)

    Jones, D.

    Xenon ion sources on an ejectable package separated from the main payload during the flights of Porcupine rockets F3 and F4 which were launched from Kiruna, Sweden on March 19 and 31, 1979, respectively. The effects of the xenon ion beam, detected by the LF (f less than 16 kHz) wideband electric field experiment and analyzed by using a sonograph, are discussed. Particular attention is given to the stimulation of the ion-cyclotron harmonic waves which are usually linked to the local proton gyro-frequency, but are sometimes related to half that frequency. It was found that in a plasma dominated by O(+) ions, a small amount (1-10%) of protons could cause an effect such that the O(+) cyclotron harmonic waves are set up by the hydrogen ions, the net result being the observation of harmonic emissions separated by the hydrogen ion gyro frequency.

  16. Jump in the amplitude of a sound wave associated with contraction of a nitrogen discharge

    SciTech Connect

    Galechyan, G.A.; Mkrtchyan, A.R.; Tavakalyan, L.B.

    1993-11-01

    The use of a sound wave created by an external source and directed along the positive column of a nitrogen discharge in order to make the discharge pass to the contracted state is studied experimentally. A phenomenon involving a jump in the sound wave amplitude, caused by the discharge contraction, is observed and studied. It is established that the amplitude of the sound wave as a function of the discharge current near the jump exhibits hysteresis. It is shown that in the field of a high-intensity sound wave causing the discharge to expand eliminates the jump in the sound amplitude. The dependence of the growth time of the sound amplitude caused by the jump in this quantity on the sound wave intensity is determined. 24 refs., 4 figs., 1 tab.

  17. Nonresonant interaction of heavy ions with electromagnetic ion cyclotron waves

    NASA Technical Reports Server (NTRS)

    Berchem, J.; Gendrin, R.

    1985-01-01

    The motion of a heavy ion in the presence of an intense ultralow-frequency electromagnetic wave propagating along the dc magnetic field is analyzed. Starting from the basic equations of motion and from their associated two invariants, the heavy ion velocity-space trajectories are drawn. It is shown that after a certain time, particles whose initial phase angles are randomly distributed tend to bunch together, provided that the wave intensity b-sub-1 is sufficiently large. The importance of these results for the interpretation of the recently observed acceleration of singly charged He ions in conjunction with the occurrence of large-amplitude ion cyclotron waves in the equatorial magnetosphere is discussed.

  18. Simultaneous observations of electrostatic oxygen cyclotron waves and ion conics

    NASA Technical Reports Server (NTRS)

    Kintner, P. M.; Scales, W.; Vago, J.; Arnoldy, R.; Garbe, G.; Moore, T.

    1989-01-01

    A sounding rocket launched to 927 km apogee during an auroral substorm encountered regions of large quasi-static electric fields (not greater than 400 mV/m), ion conics (up to 700 eV maximum observed energy), and fluctuating electric fields near the oxygen cyclotron frequency. Since the fluctuating electric fields frequently exhibited spectral peaks just above the local oxygen cyclotron frequency, and since the fluctuating electric fields were linearly polarized, they are positively identified as electrostatic oxygen cyclotron waves (EOCW). The maximum amplitude of the EOCW was about 5 mV/m rms. The EOCW closely correlated with the presence of ion conics. Because of the relatively low amplitude of the EOCW and their relatively low coherence, it cannot be concluded that they are solely responsible for the production of the ion conics.

  19. Measuring the seeds of ion outflow: auroral sounding rocket observations of low-altitude ion heating and circulation

    SciTech Connect

    Fernandes, P. A.; Lynch, K. A.; Zettergren, M.; Hampton, D. L.; Bekkeng, T. A.; Cohen, I. J.; Conde, M.; Fisher, L. E.; Horak, P.; Lessard, M. R.; Miceli, R. J.; Michell, R. G.; Moen, J.; Powell, S. P.

    2016-01-25

    Here, we present an analysis of in situ measurements from the MICA (Magnetosphere-Ionosphere Coupling in the Alfvén Resonator) nightside auroral sounding rocket with comparisons to a multifluid ionospheric model. MICA made observations at altitudes below 325 km of the thermal ion kinetic particle distributions that are the origins of ion outflow. Late flight, in the vicinity of an auroral arc, we observe frictional processes controlling the ion temperature. Upflow of these cold ions is attributed to either the ambipolar field resulting from the heated electrons or possibly to ion-neutral collisions. We measure ExB convection away from the arc (poleward) and downflows of hundreds of m s-1 poleward of this arc, indicating small-scale low-altitude plasma circulation. In the early flight we observe DC electromagnetic Poynting flux and associated ELF wave activity influencing the thermal ion temperature in regions of Alfvénic aurora. We observe enhanced, anisotropic ion temperatures which we conjecture are caused by transverse heating by wave-particle interactions (WPI) even at these low altitudes. Throughout this region we observe several hundred m s-1 upflow of the bulk thermal ions colocated with WPI; however, the mirror force is negligible at these low energies; thus, the upflow is attributed to ambipolar fields (or possibly neutral upwelling drivers). Moreover, the low-altitude MICA observations serve to inform future ionospheric modeling and simulations of (a) the need to consider the effects of heating by WPI at altitudes lower than previously considered viable and (b) the occurrence of structured and localized upflows/downflows below where higher-altitude heating rocesses are expected.

  20. Measuring the seeds of ion outflow: auroral sounding rocket observations of low-altitude ion heating and circulation

    DOE PAGES

    Fernandes, P. A.; Lynch, K. A.; Zettergren, M.; ...

    2016-01-25

    Here, we present an analysis of in situ measurements from the MICA (Magnetosphere-Ionosphere Coupling in the Alfvén Resonator) nightside auroral sounding rocket with comparisons to a multifluid ionospheric model. MICA made observations at altitudes below 325 km of the thermal ion kinetic particle distributions that are the origins of ion outflow. Late flight, in the vicinity of an auroral arc, we observe frictional processes controlling the ion temperature. Upflow of these cold ions is attributed to either the ambipolar field resulting from the heated electrons or possibly to ion-neutral collisions. We measure E→xB→ convection away from the arc (poleward) andmore » downflows of hundreds of m s-1 poleward of this arc, indicating small-scale low-altitude plasma circulation. In the early flight we observe DC electromagnetic Poynting flux and associated ELF wave activity influencing the thermal ion temperature in regions of Alfvénic aurora. We observe enhanced, anisotropic ion temperatures which we conjecture are caused by transverse heating by wave-particle interactions (WPI) even at these low altitudes. Throughout this region we observe several hundred m s-1 upflow of the bulk thermal ions colocated with WPI; however, the mirror force is negligible at these low energies; thus, the upflow is attributed to ambipolar fields (or possibly neutral upwelling drivers). Moreover, the low-altitude MICA observations serve to inform future ionospheric modeling and simulations of (a) the need to consider the effects of heating by WPI at altitudes lower than previously considered viable and (b) the occurrence of structured and localized upflows/downflows below where higher-altitude heating rocesses are expected.« less

  1. Measuring the seeds of ion outflow: Auroral sounding rocket observations of low-altitude ion heating and circulation

    NASA Astrophysics Data System (ADS)

    Fernandes, P. A.; Lynch, K. A.; Zettergren, M.; Hampton, D. L.; Bekkeng, T. A.; Cohen, I. J.; Conde, M.; Fisher, L. E.; Horak, P.; Lessard, M. R.; Miceli, R. J.; Michell, R. G.; Moen, J.; Powell, S. P.

    2016-02-01

    We present an analysis of in situ measurements from the MICA (Magnetosphere-Ionosphere Coupling in the Alfvén Resonator) nightside auroral sounding rocket with comparisons to a multifluid ionospheric model. MICA made observations at altitudes below 325 km of the thermal ion kinetic particle distributions that are the origins of ion outflow. Late flight, in the vicinity of an auroral arc, we observe frictional processes controlling the ion temperature. Upflow of these cold ions is attributed to either the ambipolar field resulting from the heated electrons or possibly to ion-neutral collisions. We measure E→×B→ convection away from the arc (poleward) and downflows of hundreds of m s-1 poleward of this arc, indicating small-scale low-altitude plasma circulation. In the early flight we observe DC electromagnetic Poynting flux and associated ELF wave activity influencing the thermal ion temperature in regions of Alfvénic aurora. We observe enhanced, anisotropic ion temperatures which we conjecture are caused by transverse heating by wave-particle interactions (WPI) even at these low altitudes. Throughout this region we observe several hundred m s-1 upflow of the bulk thermal ions colocated with WPI; however, the mirror force is negligible at these low energies; thus, the upflow is attributed to ambipolar fields (or possibly neutral upwelling drivers). The low-altitude MICA observations serve to inform future ionospheric modeling and simulations of (a) the need to consider the effects of heating by WPI at altitudes lower than previously considered viable and (b) the occurrence of structured and localized upflows/downflows below where higher-altitude heating rocesses are expected.

  2. Transmission and reflection of sound wave from a layer of liquid with gas bubbles

    NASA Astrophysics Data System (ADS)

    Gubaidullin, D. A.; Gubaidullina, D. D.; Fedorov, Yu V.

    2017-01-01

    The problem of reflection and transmission of sound wave through the two-layer medium containing a layer of bubble liquid is considered. A comparison of the reflection and transmission of wave coefficients with known experimental data is presented.

  3. Estimation of Electron Density profile Using the Propagation Characteristics of Radio Waves by S-520-29 Sounding Rocket

    NASA Astrophysics Data System (ADS)

    Itaya, K.; Ishisaka, K.; Ashihara, Y.; Abe, T.; Kumamoto, A.; Kurihara, J.

    2015-12-01

    S-520-29 sounding rocket experiment was carried out at Uchinoura Space Center (USC) at 19:10 JST on 17 August, 2014. The purpose of this sounding rocket experiments is observation of sporadic E layer that appears in the lower ionosphere at near 100km. Three methods were used in order to observe the sporadic E layer. The first method is an optical method that observe the light of metal ion emitted by the resonance scattering in sporadic E layer using the imager. The second method is observation of characteristic of radio wave propagation that the LF/MF band radio waves transmitted from the ground. The third method is measuring the electron density in the vicinity of sounding rocket using the fast Langmuir probe and the impedance probe. We analyze the propagation characteristics of radio wave in sporadic E layer appeared from the results of the second method observation. This rocket was equipped with LF/MF band radio receiver for observe the LF/MF band radio waves in rocket flight. Antenna of LF/MF band radio receiver is composed of three axis loop antenna. LF/MF band radio receiver receives three radio waves of 873kHz (JOGB), 666kHz (JOBK), 60kHz (JJY) from the ground. 873kHz and 60kHz radio waves are transmitting from north side, and 666kHz radio waves are transmitting from the east side to the trajectory of the rocket. In the sounding rocket experiment, LF/MF band radio receiver was working properly. We have completed the observation of radio wave intensity. We analyze the observation results using a Doppler shift calculations by frequency analysis. Radio waves received by the sounding rocket include the influences of Doppler shift by polarization and the direction of rocket spin and the magnetic field of the Earth. So received radio waves that are separate into characteristics waves using frequency analysis. Then we calculate the Doppler shift from the separated data. As a result, 873kHz, 666kHz radio waves are reflected by the ionosphere. 60kHz wave was able to

  4. Mississippi Sound Wave-Hindcast Study: Main Text and Appendices A and B.

    DTIC Science & Technology

    1983-04-01

    rate follows that described by Jensen (in preparation). 32. Wave conditions generated in Mississippi Sound must also con- sider dispersion effects...influence the maximum wave condition. The parametric formulation follows the work conducted by Vincent (1981). The depth-limiting maximum wave condition is...wind direction. With this information, the SWWM is now ready to compute the wave conditions throughout Mississippi Sound. This procedure is followed for

  5. Transmission of high frequency sound waves through a slug flow jet

    NASA Technical Reports Server (NTRS)

    Parthasarathy, S. P.; Vijayaraghavan, A.

    1980-01-01

    An analysis has been performed of sound waves which propagate in a pipe with gas flow. At the pipe exit these waves are partially reflected and the remainder are diffracted. The analysis is carried out by resolving the sound at the exit into its Fourier components and then continuing the solution, which is a combination of elementary plane waves, beyond the exit. These waves are of two types: homogeneous waves which propagate to infinity, and inhomogeneous waves with complex wave numbers which decay. The reflected waves are evaluated from the inhomogeneous waves. At the boundary of the jet, refraction of the elementary plane waves is accounted for and the far field sound is evaluated by the method of stationary phase. Comparisons of the theoretical calculations are made with experimental results and with calculations of other theories.

  6. Fundamentals of traveling wave ion mobility spectrometry.

    PubMed

    Shvartsburg, Alexandre A; Smith, Richard D

    2008-12-15

    Traveling wave ion mobility spectrometry (TW IMS) is a new IMS method implemented in the Synapt IMS/mass spectrometry system (Waters). Despite its wide adoption, the foundations of TW IMS were only qualitatively understood and factors governing the ion transit time (the separation parameter) and resolution remained murky. Here we develop the theory of TW IMS using derivations and ion dynamics simulations. The key parameter is the ratio (c) of ion drift velocity at the steepest wave slope to wave speed. At low c, the ion transit velocity is proportional to the squares of mobility (K) and electric field intensity (E), as opposed to linear scaling in drift tube (DT) IMS and differential mobility analyzers. At higher c, the scaling deviates from quadratic in a way controlled by the waveform profile, becoming more gradual with the ideal triangular profile but first steeper and then more gradual for realistic profiles with variable E. At highest c, the transit velocity asymptotically approaches the wave speed. Unlike with DT IMS, the resolving power of TW IMS depends on mobility, scaling as K(1/2) in the low-c limit and less at higher c. A nonlinear dependence of the transit time on mobility means that the true resolving power of TW IMS differs from that indicated by the spectrum. A near-optimum resolution is achievable over an approximately 300-400% range of mobilities. The major predicted trends are in agreement with TW IMS measurements for peptide ions as a function of mobility, wave amplitude, and gas pressure. The issues of proper TW IMS calibration and ion distortion by field heating are also discussed. The new quantitative understanding of TW IMS separations allows rational optimization of instrument design and operation and improved spectral calibration.

  7. Wind wave spectral observations in Currituck Sound, North Carolina

    NASA Astrophysics Data System (ADS)

    Long, Charles E.; Resio, Donald T.

    2007-05-01

    We examine a set of 1626 high-resolution frequency-direction wind wave spectra and collocated winds collected during a 7-month period at a site in Currituck Sound, North Carolina, in terms of one-dimensional spectral structure and directional distribution functions. The data set includes cases of shore-normal winds in broad-fetch conditions as well as winds oblique to the basin geometry, with all fetches of order 10 km or less. Using equilibrium-range scaling, all one-dimensional spectra have a spectral peak region, an equilibrium range of finite bandwidth following an f-4 slope at slightly higher frequencies, and a high-frequency tail that falls off more rapidly than f-4. For shore-normal winds, spectral peakedness appears to be high and approximately constant for young waves, low and approximately constant for old waves, and steeply graded for intermediate inverse wave ages in the range 1.0 < u10/cp < 1.7. Equilibrium-range bandwidth seems to be narrow for young waves and increases with increasing wave age. Directional distribution functions in shore-normal winds are symmetric about the wind direction, narrow at spectral peaks, and broad at high frequencies with distinct directionally bimodal peaks, consistent with other observations. In oblique-wind cases, directional distribution functions are asymmetric and directionally sheared in spectral peak regions, with peak directions aligned with longer fetch directions. At high frequencies, directional distributions are more nearly symmetric about the wind direction. One-dimensional spectra tend to have reduced spectral peakedness and highly variable equilibrium-range bandwidths in oblique-wind conditions, clearly indicating a more complex balance of source terms in these cases than in the more elementary situation of shore-normal winds. These complications are not without consequence in wave modeling, as any bounded or semibounded lake or estuary will be subject to oblique winds, and current operational models do not

  8. Method of synthesizing silica nanofibers using sound waves

    DOEpatents

    Sharma, Jaswinder K.; Datskos, Panos G.

    2015-09-15

    A method for synthesizing silica nanofibers using sound waves is provided. The method includes providing a solution of polyvinyl pyrrolidone, adding sodium citrate and ammonium hydroxide to form a first mixture, adding a silica-based compound to the solution to form a second mixture, and sonicating the second mixture to synthesize a plurality of silica nanofibers having an average cross-sectional diameter of less than 70 nm and having a length on the order of at least several hundred microns. The method can be performed without heating or electrospinning, and instead includes less energy intensive strategies that can be scaled up to an industrial scale. The resulting nanofibers can achieve a decreased mean diameter over conventional fibers. The decreased diameter generally increases the tensile strength of the silica nanofibers, as defects and contaminations decrease with the decreasing diameter.

  9. Effect of sound on gap-junction-based intercellular signaling: Calcium waves under acoustic irradiation

    NASA Astrophysics Data System (ADS)

    Deymier, P. A.; Swinteck, N.; Runge, K.; Deymier-Black, A.; Hoying, J. B.

    2015-11-01

    We present a previously unrecognized effect of sound waves on gap-junction-based intercellular signaling such as in biological tissues composed of endothelial cells. We suggest that sound irradiation may, through temporal and spatial modulation of cell-to-cell conductance, create intercellular calcium waves with unidirectional signal propagation associated with nonconventional topologies. Nonreciprocity in calcium wave propagation induced by sound wave irradiation is demonstrated in the case of a linear and a nonlinear reaction-diffusion model. This demonstration should be applicable to other types of gap-junction-based intercellular signals, and it is thought that it should be of help in interpreting a broad range of biological phenomena associated with the beneficial therapeutic effects of sound irradiation and possibly the harmful effects of sound waves on health.

  10. Effect of sound on gap-junction-based intercellular signaling: Calcium waves under acoustic irradiation.

    PubMed

    Deymier, P A; Swinteck, N; Runge, K; Deymier-Black, A; Hoying, J B

    2015-01-01

    We present a previously unrecognized effect of sound waves on gap-junction-based intercellular signaling such as in biological tissues composed of endothelial cells. We suggest that sound irradiation may, through temporal and spatial modulation of cell-to-cell conductance, create intercellular calcium waves with unidirectional signal propagation associated with nonconventional topologies. Nonreciprocity in calcium wave propagation induced by sound wave irradiation is demonstrated in the case of a linear and a nonlinear reaction-diffusion model. This demonstration should be applicable to other types of gap-junction-based intercellular signals, and it is thought that it should be of help in interpreting a broad range of biological phenomena associated with the beneficial therapeutic effects of sound irradiation and possibly the harmful effects of sound waves on health.

  11. Measurement of sound speed vs. depth in South Pole ice: pressure waves and shear waves

    SciTech Connect

    IceCube Collaboration; Klein, Spencer

    2009-06-04

    We have measured the speed of both pressure waves and shear waves as a function of depth between 80 and 500 m depth in South Pole ice with better than 1% precision. The measurements were made using the South Pole Acoustic Test Setup (SPATS), an array of transmitters and sensors deployed in the ice at the South Pole in order to measure the acoustic properties relevant to acoustic detection of astrophysical neutrinos. The transmitters and sensors use piezoceramics operating at {approx}5-25 kHz. Between 200 m and 500 m depth, the measured profile is consistent with zero variation of the sound speed with depth, resulting in zero refraction, for both pressure and shear waves. We also performed a complementary study featuring an explosive signal propagating vertically from 50 to 2250 m depth, from which we determined a value for the pressure wave speed consistent with that determined for shallower depths, higher frequencies, and horizontal propagation with the SPATS sensors. The sound speed profile presented here can be used to achieve good acoustic source position and emission time reconstruction in general, and neutrino direction and energy reconstruction in particular. The reconstructed quantities could also help separate neutrino signals from background.

  12. Sound waves and modulational instabilities on continuous-wave solutions in spinor Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Tasgal, Richard S.; Band, Y. B.

    2015-01-01

    We analyze sound waves (phonons, i.e. Bogoliubov excitations) propagating on continuous-wave (cw) solutions of repulsive F =1 spinor Bose-Einstein condensates (BECs) such as 23Na (which is antiferromagnetic or polar) and 87Rb (which is ferromagnetic). Zeeman splitting by a uniform magnetic field is included. All cw solutions to ferromagnetic BECs with vanishing MF=0 particle density and nonzero components in both MF=±1 fields are subject to modulational instability (MI). Modulational instability increases with increasing particle density. Modulational instability also increases with differences in the components' wave numbers; this effect is larger at lower densities but becomes insignificant at higher particle densities. Continuous-wave solutions to antiferromagnetic (polar) BECs with vanishing MF=0 particle density and nonzero components in both MF=±1 fields do not suffer MI if the wave numbers of the components are the same. If there is a wave-number difference, MI initially increases with increasing particle density and then peaks before dropping to zero beyond a given particle density. The cw solutions with particles in both MF=±1 components and nonvanishing MF=0 components do not have MI if the wave numbers of the components are the same, but do exhibit MI when the wave numbers are different. Direct numerical simulations of a continuous wave with weak white noise confirm that weak noise grows fastest at wave numbers with the largest MI and show some of the results beyond small-amplitude perturbations. Phonon dispersion curves are computed numerically; we find analytic solutions for the phonon dispersion in a variety of limiting cases.

  13. Propagation of sound waves through a spatially homogeneous but smoothly time-dependent medium

    SciTech Connect

    Hayrapetyan, A.G.; Grigoryan, K.K.; Petrosyan, R.G.; Fritzsche, S.

    2013-06-15

    The propagation of sound through a spatially homogeneous but non-stationary medium is investigated within the framework of fluid dynamics. For a non-vortical fluid, especially, a generalized wave equation is derived for the (scalar) potential of the fluid velocity distribution in dependence of the equilibrium mass density of the fluid and the sound wave velocity. A solution of this equation for a finite transition period τ is determined in terms of the hypergeometric function for a phenomenologically realistic, sigmoidal change of the mass density and sound wave velocity. Using this solution, it is shown that the energy flux of the sound wave is not conserved but increases always for the propagation through a non-stationary medium, independent of whether the equilibrium mass density is increased or decreased. It is found, moreover, that this amplification of the transmitted wave arises from an energy exchange with the medium and that its flux is equal to the (total) flux of the incident and the reflected wave. An interpretation of the reflected wave as a propagation of sound backward in time is given in close analogy to Feynman and Stueckelberg for the propagation of anti-particles. The reflection and transmission coefficients of sound propagating through a non-stationary medium is analyzed in more detail for hypersonic waves with transition periods τ between 15 and 200 ps as well as the transformation of infrasound waves in non-stationary oceans. -- Highlights: •Analytically exact study of sound propagation through a non-stationary medium. •Energy exchange between the non-stationary medium and the sound wave. •Transformation of hypersonic and ultrasound frequencies in non-stationary media. •Propagation of sound backward in time in close analogy to anti-particles. •Prediction of tsunamis both in spatially and temporally inhomogeneous oceans.

  14. Nonlinear ion acoustic waves scattered by vortexes

    NASA Astrophysics Data System (ADS)

    Ohno, Yuji; Yoshida, Zensho

    2016-09-01

    The Kadomtsev-Petviashvili (KP) hierarchy is the archetype of infinite-dimensional integrable systems, which describes nonlinear ion acoustic waves in two-dimensional space. This remarkably ordered system resides on a singular submanifold (leaf) embedded in a larger phase space of more general ion acoustic waves (low-frequency electrostatic perturbations). The KP hierarchy is characterized not only by small amplitudes but also by irrotational (zero-vorticity) velocity fields. In fact, the KP equation is derived by eliminating vorticity at every order of the reductive perturbation. Here, we modify the scaling of the velocity field so as to introduce a vortex term. The newly derived system of equations consists of a generalized three-dimensional KP equation and a two-dimensional vortex equation. The former describes 'scattering' of vortex-free waves by ambient vortexes that are determined by the latter. We say that the vortexes are 'ambient' because they do not receive reciprocal reactions from the waves (i.e., the vortex equation is independent of the wave fields). This model describes a minimal departure from the integrable KP system. By the Painlevé test, we delineate how the vorticity term violates integrability, bringing about an essential three-dimensionality to the solutions. By numerical simulation, we show how the solitons are scattered by vortexes and become chaotic.

  15. Electrostatic ion waves in non-Maxwellian pair-ion plasmas

    SciTech Connect

    Arshad, Kashif; Mahmood, S.

    2010-12-15

    The electrostatic ion waves are studied for non-Maxwellian or Lorentzian distributed unmagnetized pair-ion plasmas. The Vlasov equation is solved and damping rates are calculated for electrostatic waves in Lorentzian pair-ion plasmas. The damping rates of the electrostatic ion waves are studied for the equal and different ion temperatures of pair-ion species. It is found that the Landau damping rate of the ion plasma wave is increased in Lorentzian plasmas in comparison with Maxwellian pair-ion plasmas. The numerical results are also presented for illustration by taking into account the parameters reported in fullerene pair-ion plasma experiments.

  16. Excitation of instability waves in a two-dimensional shear layer by sound

    NASA Technical Reports Server (NTRS)

    Tam, C. K. W.

    1978-01-01

    The excitation of instability waves in a plane compressible shear layer by sound waves is studied. The problem is formulated mathematically as an inhomogeneous boundary-value problem. A general solution for abitrary incident sound wave is found by first constructing the Green's function of the problem. Numerical values of the coupling constants between incident sound waves and excited instability waves for a range of flow Mach number are calculated. The effect of the angle of incidence in the case of a beam of acoustic waves is analyzed. It is found that for moderate subsonic Mach numbers a narrow beam aiming at an angle between 50 to 80 deg to the flow direction is most effective in exciting instability waves.

  17. Ion acoustic wave collapse via two-ion wave decay: 2D Vlasov simulation and theory

    NASA Astrophysics Data System (ADS)

    Chapman, Thomas; Berger, Richard; Banks, Jeffrey; Brunner, Stephan

    2015-11-01

    The decay of ion acoustic waves (IAWs) via two-ion wave decay may transfer energy from the electric field of the IAWs to the particles, resulting in a significant heating of resonant particles. This process has previously been shown in numerical simulations to decrease the plasma reflectivity due to stimulated Brillouin scattering. Two-ion wave decay is a fundamental property of ion acoustic waves that occurs over most if not all of the parameter space of relevance to inertial confinement fusion experiments, and can lead to a sudden collapse of IAWs. The treatment of all species kinetically, and in particular the electrons, is required to describe the decay process correctly. We present fully kinetic 2D+2V Vlasov simulations of IAWs undergoing decay to a highly nonlinear turbulent state using the code LOKI. The scaling of the decay rate with characteristic plasma parameters and wave amplitude is shown. A new theory describing two-ion wave decay in 2D, that incorporates key kinetic properties of the electrons, is presented and used to explain quantitatively for the first time the observed decay of IAWs. Work performed under auspices of U.S. DoE by LLNL, Contract DE-AC52-07NA2734. Funded by LDRD 15-ERD-038 and supported by LLNL Grand Challenge allocation.

  18. The study of sound wave propagation in rarefied gases using unified gas-kinetic scheme

    NASA Astrophysics Data System (ADS)

    Wang, Rui-Jie; Xu, Kun

    2012-08-01

    Sound wave propagation in rarefied monatomic gases is simulated using a newly developed unified gaskinetic scheme (UGKS). The numerical calculations are carried out for a wide range of wave oscillating frequencies. The corresponding rarefaction parameter is defined as the ratio of sound wave frequency to the intermolecular particle collision frequency. The simulation covers the flow regime from the continuum to free molecule one. The treatment of the oscillating wall boundary condition and the methods for evaluating the absorption coefficient and sound wave speed are presented in detail. The simulation results from the UGKS are compared to the Navier-Stokes solutions, the direct simulation Monte Carlo (DSMC) simulation, and experimental measurements. Good agreement with the experimental data has been obtained in the whole flow regimes for the corresponding Knudsen number from 0.08 to 32. The current study clearly demonstrates the capability of the UGKS method in capturing the sound wave propagation and its usefulness for the rarefied flow study.

  19. Ion Acceleration in Plasmas with Alfven Waves

    SciTech Connect

    O.Ya. Kolesnychenko; V.V. Lutsenko; R.B. White

    2005-06-15

    Effects of elliptically polarized Alfven waves on thermal ions are investigated. Both regular oscillations and stochastic motion of the particles are observed. It is found that during regular oscillations the energy of the thermal ions can reach magnitudes well exceeding the plasma temperature, the effect being largest in low-beta plasmas (beta is the ratio of the plasma pressure to the magnetic field pressure). Conditions of a low stochasticity threshold are obtained. It is shown that stochasticity can arise even for waves propagating along the magnetic field provided that the frequency spectrum is non-monochromatic. The analysis carried out is based on equations derived by using a Lagrangian formalism. A code solving these equations is developed. Steady-state perturbations and perturbations with the amplitude slowly varying in time are considered.

  20. High-frequency sound waves to eliminate a horizon in the mixmaster universe.

    NASA Technical Reports Server (NTRS)

    Chitre, D. M.

    1972-01-01

    From the linear wave equation for small-amplitude sound waves in a curved space-time, there is derived a geodesiclike differential equation for sound rays to describe the motion of wave packets. These equations are applied in the generic, nonrotating, homogeneous closed-model universe (the 'mixmaster universe,' Bianchi type IX). As for light rays described by Doroshkevich and Novikov (DN), these sound rays can circumnavigate the universe near the singularity to remove particle horizons only for a small class of these models and in special directions. Although these results parallel those of DN, different Hamiltonian methods are used for treating the Einstein equations.

  1. Source and listener directivity for interactive wave-based sound propagation.

    PubMed

    Mehra, Ravish; Antani, Lakulish; Kim, Sujeong; Manocha, Dinesh

    2014-04-01

    We present an approach to model dynamic, data-driven source and listener directivity for interactive wave-based sound propagation in virtual environments and computer games. Our directional source representation is expressed as a linear combination of elementary spherical harmonic (SH) sources. In the preprocessing stage, we precompute and encode the propagated sound fields due to each SH source. At runtime, we perform the SH decomposition of the varying source directivity interactively and compute the total sound field at the listener position as a weighted sum of precomputed SH sound fields. We propose a novel plane-wave decomposition approach based on higher-order derivatives of the sound field that enables dynamic HRTF-based listener directivity at runtime. We provide a generic framework to incorporate our source and listener directivity in any offline or online frequency-domain wave-based sound propagation algorithm. We have integrated our sound propagation system in Valve's Source game engine and use it to demonstrate realistic acoustic effects such as sound amplification, diffraction low-passing, scattering, localization, externalization, and spatial sound, generated by wave-based propagation of directional sources and listener in complex scenarios. We also present results from our preliminary user study.

  2. A volume-based hydrodynamic approach to sound wave propagation in a monatomic gas

    NASA Astrophysics Data System (ADS)

    Dadzie, S. Kokou; Reese, Jason M.

    2010-01-01

    We investigate sound wave propagation in a monatomic gas using a volume-based hydrodynamic model. In Dadzie et al. [Physica A 387, 6079 (2008)], a microscopic volume-based kinetic approach was proposed by analyzing molecular spatial distributions; this led to a set of hydrodynamic equations incorporating a mass-density diffusion component. Here we find that these new mass-density diffusive flux and volume terms mean that our hydrodynamic model, uniquely, reproduces sound wave phase speed and damping measurements with excellent agreement over the full range of Knudsen number. In the high Knudsen number (high frequency) regime, our volume-based model predictions agree with the plane standing waves observed in the experiments, which existing kinetic and continuum models have great difficulty in capturing. In that regime, our results indicate that the "sound waves" presumed in the experiments may be better thought of as "mass-density waves," rather than pressure waves.

  3. Hazardous sound levels produced by extracorporeal shock wave lithotripsy

    SciTech Connect

    Lusk, R.P.; Tyler, R.S.

    1987-06-01

    Sound emitted from the Dornier system GmbH lithotriptor was found to be of sufficient intensity to warrant concern about noise-induced sensorineural hearing loss. The patients were exposed to impulses of 112 dB. peak sound pressure level. Operating room personnel were exposed to sounds of less intensity, although the number of impulses they were exposed to was much greater, thereby increasing the risk of hearing loss. Hearing protection is recommended for patients and operating room personnel.

  4. Sound Radiated by a Wave-Like Structure in a Compressible Jet

    NASA Technical Reports Server (NTRS)

    Golubev, V. V.; Prieto, A. F.; Mankbadi, R. R.; Dahl, M. D.; Hixon, R.

    2003-01-01

    This paper extends the analysis of acoustic radiation from the source model representing spatially-growing instability waves in a round jet at high speeds. Compared to previous work, a modified approach to the sound source modeling is examined that employs a set of solutions to linearized Euler equations. The sound radiation is then calculated using an integral surface method.

  5. Diagnosis of ankylosis in permanent incisors by expert ratings, Periotest and digital sound wave analysis.

    PubMed

    Campbell, Karen M; Casas, Michael J; Kenny, David J; Chau, Tom

    2005-08-01

    The objectives of this investigation were to: (i) assess the reliability of expert raters to detect ankylosis from recordings of percussion sounds, (ii) measure differences in Periotest values (PTV) between ankylosed and non-ankylosed incisors and (iii) identify characteristic differences in recorded percussion sounds from ankylosed and non-ankylosed incisors using digital sound wave analysis. A convenience sample of healthy children (age range 7-18 years) was invited to participate. Ankylosis group children had one or more documented ankylosed maxillary incisors. Control group children had intact, non-ankylosed incisors. Digital recordings of percussion sounds and PTV were acquired for each incisor of interest. Four experienced pediatric dentists rated the randomized percussion sound pairs for the presence of ankylosis. Percussion sounds were also subjected to digital sound wave analysis. Overall agreement for the expert raters was substantial (kappa = 0.7). Intra-rater agreement was substantial to almost perfect (kappa = 0.6-0.9). Diagnosis of ankylosis demonstrated sensitivity of 76-92% and specificity of 74-100%. PTV from ankylosed incisors were statistically lower than PTV from non-ankylosed incisors. Ankylosed incisor digital sound wave signals exhibited significantly more energy in high-frequency bands than non-ankylosed incisors. This investigation demonstrated that: (i) experienced pediatric dentists reliably detected ankylosis by percussion sound alone; (ii) PTV for ankylosed incisors were statistically lower than PTV from non-ankylosed incisors; and (iii) ankylosed incisors exhibited a higher proportion of their signal energy in high-frequency bands.

  6. Sound generation and upstream influence due to instability waves interacting with non-uniform mean flows

    NASA Technical Reports Server (NTRS)

    Goldstein, M. E.

    1984-01-01

    Attention is given to the sound produced by artificially excited, spatially growing instability waves on subsonic shear layers. Real flows that always diverge in the downstream direction allow sound to be produced by the interaction of the instability waves with the resulting streamwise variations of the flow. The upstream influence, or feedback, can interact with the splitter plate lip to produce a downstream-propagating instability wave that may under certain conditions be the same instability wave that originally generated the upstream influence. The present treatment is restricted to very low Mach number flows, so that compressibility effects can only become important over large distances.

  7. Effective isolation of primo vessels in lymph using sound- and ultrasonic-wave stimulation.

    PubMed

    Park, Do-Young; Lee, Hye-Rie; Rho, Min-Suk; Lee, Sang-Suk

    2014-12-01

    The effects of stimulation with sound and ultrasonic waves of a specific bandwidth on the microdissection of primo vessels in lymphatic vessels of rabbit were investigated. The primo vessels stained with alcian-blue dye injected in the lymph nodes were definitely visualized and more easily isolated by sound-wave vibration and ultrasonic stimulation applied to rabbits at various frequencies and intensities. With sound wave at 7 Hz and ultrasonic waves at 2 MHz, the probability of detecting the primo vessels was improved to 90%; however, without wave stimulation the probability of discovering primo vessels was about 50% only. Sound and ultrasonic waves at specific frequency bands should be effective for microdissection of the primo vessels in the abdominal lymph of rabbit. We suggest that oscillation of the primo vessels by sound and ultrasonic waves may be useful to visualize specific primo structure, and wave vibration can be a very supportive process for observation and isolation of the primo vessels of rabbits.

  8. A nonlinear acoustic metamaterial: Realization of a backwards-traveling second-harmonic sound wave.

    PubMed

    Quan, Li; Qian, Feng; Liu, Xiaozhou; Gong, Xiufen

    2016-06-01

    An ordinary waveguide with periodic vibration plates and side holes can realize an acoustic metamaterial that simultaneously possesses a negative bulk modulus and a negative mass density. The study is further extended to a nonlinear case and it is predicted that a backwards-traveling second-harmonic sound wave can be obtained through the nonlinear propagation of a sound wave in such a metamaterial.

  9. Discrimination Among Wave-Generated Sounds by a Swash-Riding Clam.

    PubMed

    Ellers, O

    1995-10-01

    Clams, Donax variabilis, responded to sound stimuli presented to them in a laboratory aquarium by jumping out of the sand, lying on the sand for several seconds, and digging in again. On a beach, clams jump out of the sand and ride waves, migrating shoreward with the rising tide and seaward with the falling tide. Parallels between clam behavior on a beach and that elicited in the laboratory suggest that clams cue on wave sounds to jump out of the sand. Three aspects of the response to sound were parallel. (i) Clams were most responsive to low-frequency sounds similar to those produced on a beach by waves rolling onto shore. (ii) Clams were also more responsive to louder sounds; on a beach, clams jump preferentially for the largest (loudest) 20% of waves, (iii) Responsiveness in the laboratory had an endogenous tidal rhythm, with highest activity occurring at high tide and no activity occurring at low tide; this rhythm corresponds to the activity of clams on the beach from which they were collected. By using sounds to identify large waves, clams can ride selected waves and continuously maintain position at the sea's edge as the tide floods and ebbs.

  10. Ion Cyclotron Waves in the VASIMR

    NASA Astrophysics Data System (ADS)

    Brukardt, M. S.; Bering, E. A.; Chang-Diaz, F. R.; Squire, J. P.; Longmier, B.

    2008-12-01

    The Variable Specific Impulse Magnetoplasma Rocket is an electric propulsion system under development at Ad Astra Rocket Company that utilizes several processes of ion acceleration and heating that occur in the Birkeland currents of an auroral arc system. Among these processes are parallel electric field acceleration, lower hybrid resonance heating, and ion cyclotron resonance heating. The VASIMR is capable of laboratory simulation of electromagnetic ion cyclotron wave heating during a single pass of the plasma through the resonance region. The plasma is generated by a helicon discharge of about 25 kW then passes through an RF booster stage that shoots left hand polarized slow mode waves from the high field side of the resonance. This paper will focus on the upgrades to the VX-200 test model over the last year. After summarizing the VX- 50 and VX-100 results, the new data from the VX-200 model will be presented. Lastly, the changes to the VASIMR experiment due to Ad Astra Rocket Company's new facility in Webster, Texas will also be discussed, including the possibility of collaborative experiments at the new facility.

  11. Effect of Disorder on Bulk Sound Wave Speed : A Multiscale Spectral Analysis.

    NASA Astrophysics Data System (ADS)

    Shrivastava, Rohit; Luding, Stefan

    2016-04-01

    Disorder in the form of size (polydispersity) and mass of discrete elements/particles in a disordered media (a granular matter like soil) have numerous effects on it's sound propagation characteristics [1,2]. The influence of disorder on the sound wave speed and it's frequency filtering characteristics is the subject of investigation. The study will assist in understanding the connection between particle-scale dynamics and system-scale behavior of wave propagation which can be further used for modeling during non-destructive testing, seismic exploration of buried objects (oil, mineral, etc.) or to study the internal structure of the Earth. Studying the wave propagation characteristics through Discrete Element Models with varying polydispersity and mass of discrete elements in real-time, frequency space as well as through dispersion curves (ω (frequency) v/s k (wavenumber)) can shed light on this aspect by providing better microscopic understanding. To isolate the P-wave from shear and rotational modes, a one-dimensional system of elements/particles is used to study the effect of mass disorder on bulk sound wave speed through ensemble averaging of signals. Increasing polydispersity/disorder decreases the sound wave speed because of decrease in the number of contacts between particles [2] but, in contrast, increasing mass disorder increases the sound wave speed (in 1 D chains). Thus we conclude that a competition exists between these two kinds of disorder for their influence on the bulk sound wave speed. References [1] Brian P. Lawney and Stefan Luding. Frequency filtering in disordered granular chains. Acta Mechanica, 225(8):2385-2407, 2014. [2] O. Mouraille and S. Luding. Sound wave propagation in weakly polydisperse granular materials. Ultrasonics, 48(6-7):498 - 505, 2008. Selected Papers from ICU 2007.

  12. Acceleration of solitary ion-acoustic surface waves

    NASA Astrophysics Data System (ADS)

    Stenflo, L.; Gradov, O. M.

    1991-10-01

    We consider the interaction between long-wavelength ion-acoustic and electron-plasma surface waves on a semi-infinite plasma. It then turns out that an ion-acoustic solitary wave can be accelerated when the amplitude of the electron-plasma surface wave varies in time.

  13. Influence of Sound Wave Stimulation on the Growth of Strawberry in Sunlight Greenhouse

    NASA Astrophysics Data System (ADS)

    Qi, Lirong; Teng, Guanghui; Hou, Tianzhen; Zhu, Baoying; Liu, Xiaona

    In this paper, we adopt the QGWA-03 plant audio apparatus to investigate the sound effects on strawberry in the leaf area, the photosynthetic characteristics and other physiological indexes. It was found that when there were no significant differences between the circumstances of the two sunlight greenhouses, the strawberry after the sound wave stimulation grew stronger than in the control and its leaf were deeper green, and shifted to an earlier time about one week to blossom and bear fruit. It was also found that the resistance of strawberry against disease and insect pest were enhanced. The experiment results show that sound wave stimulation can certainly promote the growth of plants.

  14. High-frequency sound wave propagation in binary gas mixtures flowing through microchannels

    NASA Astrophysics Data System (ADS)

    Bisi, M.; Lorenzani, S.

    2016-05-01

    The propagation of high-frequency sound waves in binary gas mixtures flowing through microchannels is investigated by using the linearized Boltzmann equation based on a Bhatnagar-Gross-Krook (BGK)-type approach and diffuse reflection boundary conditions. The results presented refer to mixtures whose constituents have comparable molecular mass (like Ne-Ar) as well as to disparate-mass gas mixtures (composed of very heavy plus very light molecules, like He-Xe). The sound wave propagation model considered in the present paper allows to analyze the precise nature of the forced-sound modes excited in different gas mixtures.

  15. Nonlinear interactions in superfluid dynamics: Nonstationary heat transfer due to second sound shock waves

    NASA Technical Reports Server (NTRS)

    Liepmann, H. W.; Torczynski, J. R.

    1983-01-01

    Second sound techniques were used to study superfluid helium. Second sound shock waves produced relative velocities in the bulk fluid. Maximum counterflow velocities produced in this way are found to follow the Langer-Fischer prediction for the fundamental critical velocity in its functional dependence on temperature and pressure. Comparison of successive shock and rotating experiments provides strong evidence that breakdown results in vorticity production in the flow behind the shock. Schlieren pictures have verified the planar nature of second sound shocks even after multiple reflections. The nonlinear theory of second sound was repeatedly verified in its prediction of double shocks and other nonlinear phenomena.

  16. Wave field synthesis of a sound field described by spherical harmonics expansion coefficients.

    PubMed

    Ahrens, Jens; Spors, Sascha

    2012-03-01

    Near-field compensated higher order Ambisonics (NFC-HOA) and wave field synthesis (WFS) constitute the two best-known analytic sound field synthesis methods. While WFS is typically used for the synthesis of virtual sound scenes, NFC-HOA is typically employed in order to synthesize sound fields that have been captured with appropriate microphone arrays. Such recorded sound fields are essentially represented by the coefficients of the underlying surface spherical harmonics expansion. A sound field described by such coefficients cannot be straightforwardly synthesized in WFS. This is a consequence of the fact that, unlike in NFC-HOA, it is critical in WFS to carefully select those loudspeakers that contribute to the synthesis of a given sound source in a sound field under consideration. In order to enable such a secondary source selection, it is proposed to employ the well-known concept of decomposing the sound field under consideration into a continuum of plane waves, for which the secondary source selection is straightforward. The plane wave representation is projected onto the horizontal plane and a closed form expression of the secondary source driving signals for horizontal WFS systems of arbitrary convex shape is derived.

  17. Wave field synthesis of moving virtual sound sources with complex radiation properties.

    PubMed

    Ahrens, Jens; Spors, Sascha

    2011-11-01

    An approach to the synthesis of moving virtual sound sources with complex radiation properties in wave field synthesis is presented. The approach exploits the fact that any stationary sound source of finite spatial extent radiates spherical waves at sufficient distance. The angular dependency of the radiation properties of the source under consideration is reflected by the amplitude and phase distribution on the spherical wave fronts. The sound field emitted by a uniformly moving monopole source is derived and the far-field radiation properties of the complex virtual source under consideration are incorporated in order to derive a closed-form expression for the loudspeaker driving signal. The results are illustrated via numerical simulations of the synthesis of the sound field of a sample moving complex virtual source.

  18. Second sound shock waves and critical velocities in liquid helium 2. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Turner, T. N.

    1979-01-01

    Large amplitude second-sound shock waves were generated and the experimental results compared to the theory of nonlinear second-sound. The structure and thickness of second-sound shock fronts are calculated and compared to experimental data. Theoretically it is shown that at T = 1.88 K, where the nonlinear wave steepening vanishes, the thickness of a very weak shock must diverge. In a region near this temperature, a finite-amplitude shock pulse evolves into an unusual double-shock configuration consisting of a front steepened, temperature raising shock followed by a temperature lowering shock. Double-shocks are experimentally verified. It is experimentally shown that very large second-sound shock waves initiate a breakdown in the superfluidity of helium 2, which is dramatically displayed as a limit to the maximum attainable shock strength. The value of the maximum shock-induced relative velocity represents a significant lower bound to the intrinsic critical velocity of helium 2.

  19. Teaching about Mechanical Waves and Sound with a Tuning Fork and the Sun

    ERIC Educational Resources Information Center

    Leccia, Silvio; Colantonio, Arturo; Puddu, Emanuella; Galano, Silvia; Testa, Italo

    2015-01-01

    Literature in "Physics Education" has shown that students encounter many difficulties in understanding wave propagation. Such difficulties lead to misconceptions also in understanding sound, often used as context to teach wave propagation. To address these issues, we present in this paper a module in which the students are engaged in…

  20. Stopping power of charged particles due to ion wave excitations.

    PubMed

    Nitta, H; Muroki, C; Nambu, M

    2002-08-01

    Stopping power due to ion wave excitations is derived for a charged particle moving in a two-component plasma. Unlike previous theories based on ion-acoustic-wave approximation (IAWA), the excitation of short-wavelength ion waves is taken into account. The obtained stopping power has a magnitude larger than that of IAWA. Stopping power at subsonic velocities, where stopping power in IAWA disappears, is even larger than that of supersonic velocities.

  1. Stopping power of charged particles due to ion wave excitations

    NASA Astrophysics Data System (ADS)

    Nitta, H.; Muroki, C.; Nambu, M.

    2002-08-01

    Stopping power due to ion wave excitations is derived for a charged particle moving in a two-component plasma. Unlike previous theories based on ion-acoustic-wave approximation (IAWA), the excitation of short-wavelength ion waves is taken into account. The obtained stopping power has a magnitude larger than that of IAWA. Stopping power at subsonic velocities, where stopping power in IAWA disappears, is even larger than that of supersonic velocities.

  2. Recurrence of initial state of nonlinear ion waves

    SciTech Connect

    Abe, K.; Satofuka, N.

    1981-06-01

    By solving the Korteweg--deVries equation in a wide range of the ratio between the nonlinearity and the dispersion, the recurrence of the initial state of the ion wave is examined. The recurrence is assured of taking place only when the dispersion of the initial ion wave predominates over the nonlinearity. If the initial wave has strong nonlinearity compared with the dispersion, the recurrence is indistinct, and the initial monochromatic wave evolves to a turbulent state.

  3. Biodamage via shock waves initiated by irradiation with ions.

    PubMed

    Surdutovich, Eugene; Yakubovich, Alexander V; Solov'yov, Andrey V

    2013-01-01

    Radiation damage following the ionising radiation of tissue has different scenarios and mechanisms depending on the projectiles or radiation modality. We investigate the radiation damage effects due to shock waves produced by ions. We analyse the strength of the shock wave capable of directly producing DNA strand breaks and, depending on the ion's linear energy transfer, estimate the radius from the ion's path, within which DNA damage by the shock wave mechanism is dominant. At much smaller values of linear energy transfer, the shock waves turn out to be instrumental in propagating reactive species formed close to the ion's path to large distances, successfully competing with diffusion.

  4. Stochastic Ion Heating by the Lower-Hybrid Waves

    NASA Technical Reports Server (NTRS)

    Khazanov, G.; Tel'nikhin, A.; Krotov, A.

    2011-01-01

    The resonance lower-hybrid wave-ion interaction is described by a group (differentiable map) of transformations of phase space of the system. All solutions to the map belong to a strange attractor, and chaotic motion of the attractor manifests itself in a number of macroscopic effects, such as the energy spectrum and particle heating. The applicability of the model to the problem of ion heating by waves at the front of collisionless shock as well as ion acceleration by a spectrum of waves is discussed. Keywords: plasma; ion-cyclotron heating; shocks; beat-wave accelerator.

  5. Parametric decays of electromagnetic ion cyclotron waves in a H{sup +}-He{sup +}-O{sup +} magnetosphericlike plasma

    SciTech Connect

    Gomberoff, L.; Gnavi, G.; Gratton, F.T.

    1995-09-01

    Parametric decays of large-amplitude electromagnetic ion cyclotron waves (EICW) due to a minor {Omicron}{sup +} ion component in the magnetosphere are studied. It is shown that the presence of {Omicron}{sup +} ions leads to a number of new wave couplings which in turn lead to new instabilities. Some coupling involve sound waves carried mainly by the {Omicron}{sup +} ions, and a sideband EICW which has a resonace at the {Omicron}{sup +} ion gyrofrequency. These are decay instabilities which can lead to {Omicron}{sup +} heating through Landau damping and/or resonance absorption. There is also a modulational instability involving two sideband EICW, one propagating forward and the other propagating backward relative to the external magnetic field. These waves can also transfer energy to the {Omicron}{sup +} ions through resonance absorption. The other branches of the dispersion relation, namely, the He{sup +} and proton branch, have additional decay instabilities due to the presence of a minor {Omicron}{sup +} ion component. It is also shown that in the fluid description, the decays to sound waves associated with the minority heavy ion species have growth rates comparable to, or even larger than, the decays to the acoustic branch corresponding to the majority proton species. 44 refs., 5 figs.

  6. Thermal and viscous effects on sound waves: revised classical theory.

    PubMed

    Davis, Anthony M J; Brenner, Howard

    2012-11-01

    In this paper the recently developed, bi-velocity model of fluid mechanics based on the principles of linear irreversible thermodynamics (LIT) is applied to sound propagation in gases taking account of first-order thermal and viscous dissipation effects. The results are compared and contrasted with the classical Navier-Stokes-Fourier results of Pierce for this same situation cited in his textbook. Comparisons are also made with the recent analyses of Dadzie and Reese, whose molecularly based sound propagation calculations furnish results virtually identical with the purely macroscopic LIT-based bi-velocity results below, as well as being well-supported by experimental data. Illustrative dissipative sound propagation examples involving application of the bi-velocity model to several elementary situations are also provided, showing the disjoint entropy mode and the additional, evanescent viscous mode.

  7. Sounding rocket observations of precipitating ions in the morning auroral region

    SciTech Connect

    Clemmons, J.H.

    1992-01-01

    The origin of highly-structured ion fluxes measured by a sounding rocket launched into the morning auroral region on January 23, 1985 is investigated. The energy spectra of the precipitating ions exhibit an energy-time dependence in which particles of higher energies arrived at the rocket before those of lower energies. The spectra are interpreted as being due to the impulsive injection of particles onto high-altitude magnetic field lines, followed by their subsequent drift down the field lines to rocket altitudes. The dispersal to low energies with increasing time is explained as a time-of-flight effect in which the slower particles take longer times to traverse the distance. The ion signatures are used to constrain several possible physical models which characterize the source region. Source locations in the nightside magnetopause boundary layer are deduced through the examination of electron energy spectra and the use of a magnetospheric magnetic field model. The modeling efforts indicate that the data are consistent with sources located in the mid-latitude region of the flank boundary layer on the morning side of the magnetosphere, being in the range of 20-30 earth radii down the geomagnetic tail from the earth. Multiple injections of ions are observed, with a deduced quasi-periodicity of 100-200 s. Several candidate injection mechanisms are examined, with a mechanism related to the propagation of waves on the surface of the boundary layer found to be the most plausible explanation for the observations. Comparison is made to similar analyses by others and suggestions for future work are made.

  8. Intensity statistics of very high frequency sound scattered from wind-driven waves.

    PubMed

    Walstead, Sean P; Deane, Grant B

    2016-05-01

    The interaction of vhf 100-1000 kHz underwater sound with the ocean surface is explored. The bistatic forward scatter of 300 kHz sound is measured in a wind driven wave channel. Fluctuations in arrival amplitude are described by the scintillation index (SI) which is a measure of arrival intensity variance. SI initially increases with wind speed but eventually saturates to a value of 0.5 when the root-mean-square (rms) roughness is 0.5 mm. An adjusted scintillation index (SI*) is suggested that accounts for the multiple arrivals and properly saturates to a value of 1. Fluctuations in arrival time do not saturate and increase proportionately to the dominant surface wave component. Forward scattering is modeled at frequencies ranging from 50 to 2000 kHz using the Helmholtz-Kirchhoff integral with surface wave realizations derived from wave gauge data. The amplitude and temporal statistics of the simulated scattering agree well with measured data. Intensity saturation occurs at lower wind speeds for higher frequency sound. Both measured and modeled vhf sound is characterized by many surface arrivals at saturation. Doppler shifts associated with wave motion are expected to vary rapidly for vhf sound however further analysis is required.

  9. Ion acoustic shock wave in collisional equal mass plasma

    SciTech Connect

    Adak, Ashish; Ghosh, Samiran; Chakrabarti, Nikhil

    2015-10-15

    The effect of ion-ion collision on the dynamics of nonlinear ion acoustic wave in an unmagnetized pair-ion plasma has been investigated. The two-fluid model has been used to describe the dynamics of both positive and negative ions with equal masses. It is well known that in the dynamics of the weakly nonlinear wave, the viscosity mediates wave dissipation in presence of weak nonlinearity and dispersion. This dissipation is responsible for the shock structures in pair-ion plasma. Here, it has been shown that the ion-ion collision in presence of collective phenomena mediated by the plasma current is the source of dissipation that causes the Burgers' term which is responsible for the shock structures in equal mass pair-ion plasma. The dynamics of the weakly nonlinear wave is governed by the Korteweg-de Vries Burgers equation. The analytical and numerical investigations revealed that the ion acoustic wave exhibits both oscillatory and monotonic shock structures depending on the frequency of ion-ion collision parameter. The results have been discussed in the context of the fullerene pair-ion plasma experiments.

  10. Parasitic excitation of ion Bernstein waves from a Faraday shielded fast wave loop antenna

    SciTech Connect

    Skiff, F.; Ono, M.; Colestock, P.; Wong, K.L.

    1984-12-01

    Parasitic excitation of ion Bernstein waves is observed from a Faraday shielded fast wave loop antenna in the ion cyclotron frequency range. Local analysis of the Vlasov-Maxwell equations demonstrates the role of plasma density gradient in the coupling process. The effects of plasma density and of parallel wave number on the excitation process are investigated.

  11. Heating of ionospheric O(+) ions by shear Alfven waves

    NASA Technical Reports Server (NTRS)

    Winglee, R. M.; Ashour-Abdalla, M.; Sydora, R. D.

    1987-01-01

    Ionospheric ions, in particular O(+) ions, which have been transversely heated, are often observed flowing upward along auroral field lines. A new mechanism, heating by current-driven shear (or kinetic) Alfven waves (SAW), is proposed. An electron current drives oblique SAWs unstable near a wave frequency of about the oxygen cyclotron frequency, and these waves are in turn gyroresonantly absorbed by the ions. The mechanism is similar to ion heating by current-driven electrostatic ion cyclotron waves (EICW). However, the SAW differs from the EICW in that as the perpendicular temperature of the ions increases, growth of the SAW can still occur, whereas growth of the EICW becomes suppressed. As a consequence, the SAW is able to provide sustained perpendicular heating of ions with smaller currents being required for the heating than for heating via EICWs.

  12. Nonlinear particle simulation of ion cyclotron waves in toroidal geometry

    SciTech Connect

    Kuley, A. Lin, Z.; Bao, J.; Wei, X. S.; Xiao, Y.

    2015-12-10

    Global particle simulation model has been developed in this work to provide a first-principles tool for studying the nonlinear interactions of radio frequency (RF) waves with plasmas in tokamak. In this model, ions are considered as fully kinetic particles using the Vlasov equation and electrons are treated as guiding centers using the drift kinetic equation with realistic electron-to-ion mass ratio. Boris push scheme for the ion motion has been developed in the toroidal geometry using magnetic coordinates and successfully verified for the ion cyclotron and ion Bernstein waves in global gyrokinetic toroidal code (GTC). The nonlinear simulation capability is applied to study the parametric decay instability of a pump wave into an ion Bernstein wave side band and a low frequency ion cyclotron quasi mode.

  13. Nonlinear particle simulation of ion cyclotron waves in toroidal geometry

    NASA Astrophysics Data System (ADS)

    Kuley, A.; Bao, J.; Lin, Z.; Wei, X. S.; Xiao, Y.

    2015-12-01

    Global particle simulation model has been developed in this work to provide a first-principles tool for studying the nonlinear interactions of radio frequency (RF) waves with plasmas in tokamak. In this model, ions are considered as fully kinetic particles using the Vlasov equation and electrons are treated as guiding centers using the drift kinetic equation with realistic electron-to-ion mass ratio. Boris push scheme for the ion motion has been developed in the toroidal geometry using magnetic coordinates and successfully verified for the ion cyclotron and ion Bernstein waves in global gyrokinetic toroidal code (GTC). The nonlinear simulation capability is applied to study the parametric decay instability of a pump wave into an ion Bernstein wave side band and a low frequency ion cyclotron quasi mode.

  14. Sound power spectrum and wave drag of a propeller in flight

    NASA Technical Reports Server (NTRS)

    Hanson, D. B.

    1989-01-01

    Theory is presented for the sound power and sound power spectrum of a single rotation propeller in forward flight. Calculations are based on the linear wave equation with sources distributed over helicoidal surfaces to represent effects of blade thickness and steady loading. Sound power is distributed continuously over frequecy, as would be expected from Doppler effects, rather than in discrete harmonics. The theory is applied to study effects of sweep and Mach number in propfans. An acoustic efficiency is defined as the ratio of radiated sound power to shaft input power. This value is the linear estimate of the effect of wave drag due to the supersonic blade section speeds. It is shown that the acoustic efficiency is somewhat less than 1 percent for a well designed propfan.

  15. Sound waves in two-dimensional ducts with sinusoidal walls

    NASA Technical Reports Server (NTRS)

    Nayfeh, A. H.

    1974-01-01

    The method of multiple scales is used to analyze the wave propagation in two-dimensional hard-walled ducts with sinusoidal walls. For traveling waves, resonance occurs whenever the wall wavenumber is equal to the difference of the wavenumbers of any two duct acoustic modes. The results show that neither of these resonating modes could occur without strongly generating the other.

  16. Creating and studying ion acoustic waves in ultracold neutral plasmas

    SciTech Connect

    Killian, T. C.; Castro, J.; McQuillen, P.; O'Neil, T. M.

    2012-05-15

    We excite ion acoustic waves in ultracold neutral plasmas by imprinting density modulations during plasma creation. Laser-induced fluorescence is used to observe the density and velocity perturbations created by the waves. The effect of expansion of the plasma on the evolution of the wave amplitude is described by treating the wave action as an adiabatic invariant. After accounting for this effect, we determine that the waves are weakly damped, but the damping is significantly faster than expected for Landau damping.

  17. Nonlinear evolution of high frequency R-mode waves excited by water group ions near comets - Computer experiments

    NASA Technical Reports Server (NTRS)

    Kojima, H.; Matsumoto, H.; Omura, Y.; Tsurutani, B. T.

    1989-01-01

    An ion beam resonates with R-mode waves at a high-frequency RH mode and a low-frequency RL mode. The nonlinear evolution of ion beam-generated RH waves is studied here by one-dimensional hybrid computer experiments. Both wave-particle and subsequent wave-wave interactions are examined. The competing process among coexisting RH and RL mode beam instabilities and repeated decay instabilities triggered by the beam-excited RH mode waves is clarified. It is found that the quenching of the RH instability is not caused by a thermal spreading of the ion beam, but by the nonlinear wave-wave coupling process. The growing RH waves become unstable against the decay instability. This instability involves a backward-traveling RH electromagnetic wave and a forward-traveling longitudinal sound wave. The inverse cascading process is found to occur faster than the growth of the RL mode. Wave spectra decaying from the RH waves weaken as time elapses and the RL mode waves become dominant at the end of the computer experiment.

  18. Detailed study of nonlinear wave front distortion of focused sound in superfluid4He

    NASA Astrophysics Data System (ADS)

    Sasaki, Yasuo; Kishi, Hidenobu; Karaki, Koichi; Okuda, Yuichi

    1995-02-01

    We have investigated a nonlinear phenomenon which appears in a focused sound in superfluid4He under pressure higher than 18 atm. Wave front distortion of the focused ultrasound by nonlinear effect was obtained by the Fourier transform of the transducer output as a function of the defocusing length. The wave was found to suffer discontinuous wave front distortion for the input power above a certain value. This distortion is well represented by the picture that a second wave whose phase is shifted by approx. π develops, and interferes with the original wave. The amplitude of this second wave decreases suddenly as the pressure is lowered below 18 atm and the nonlinear wave front distortion also disappears. The possible mechanism of this second wave generation are discussed.

  19. Sensory illusions: Common mistakes in physics regarding sound, light and radio waves

    NASA Astrophysics Data System (ADS)

    Briles, T. M.; Tabor-Morris, A. E.

    2013-03-01

    Optical illusions are well known as effects that we see that are not representative of reality. Sensory illusions are similar but can involve other senses than sight, such as hearing or touch. One mistake commonly noted among instructors is that students often mis-identify radio signals as sound waves and not as part of the electromagnetic spectrum. A survey of physics students from multiple high schools highlights the frequency of this common misconception, as well as other nuances on this misunderstanding. Many students appear to conclude that, since they experience radio broadcasts as sound, then sound waves are the actual transmission of radio signals and not, as is actually true, a representation of those waves as produced by the translator box, the radio. Steps to help students identify and correct sensory illusion misconceptions are discussed. School of Education

  20. Quantum ion-acoustic wave oscillations in metallic nanowires

    SciTech Connect

    Moradi, Afshin

    2015-05-15

    The low-frequency electrostatic waves in metallic nanowires are studied using the quantum hydrodynamic model, in which the electron and ion components of the system are regarded as a two-species quantum plasma system. The Poisson equation as well as appropriate quantum boundary conditions give the analytical expressions of dispersion relations of the surface and bulk quantum ion-acoustic wave oscillations.

  1. Motion of a rigid prolate spheroid in a sound wave field.

    PubMed

    Zhou, Hongkun; Hong, Lianjin

    2014-08-01

    The motions of a rigid and unconstrained prolate spheroid subjected to plane sound waves are computed using preliminary analytic derivation and numerical approach. The acoustically induced motions are found comprising torsional motion as well as translational motion in the case of acoustic oblique incidence and present great relevance to the sound wavelength, body geometry, and density. The relationship between the motions and acoustic particle velocity is obtained through finite element simulation in terms of sound wavelengths much longer than the overall size of the prolate spheroid. The results are relevant to the design of inertial acoustic particle velocity sensors based on prolate spheroids.

  2. Adaptive wave field synthesis for active sound field reproduction: experimental results.

    PubMed

    Gauthier, Philippe-Aubert; Berry, Alain

    2008-04-01

    Sound field reproduction has applications in music reproduction, spatial audio, sound environment reproduction, and experimental acoustics. Sound field reproduction can be used to artificially reproduce the spatial character of natural hearing. The objective is then to reproduce a sound field in a real reproduction environment. Wave field synthesis (WFS) is a known open-loop technology which assumes that the reproduction environment is anechoic. The room response thus reduces the quality of the physical sound field reproduction by WFS. In recent research papers, adaptive wave field synthesis (AWFS) was defined as a potential solution to compensate for these quality reductions from which WFS objective performance suffers. In this paper, AWFS is experimentally investigated as an active sound field reproduction system with a limited number of reproduction error sensors to compensate for the response of the listening environment. Two digital signal processing algorithms for AWFS are used for comparison purposes, one of which is based on independent radiation mode control. AWFS performed propagating sound field reproduction better than WFS in three tested reproduction spaces (hemianechoic chamber, standard laboratory space, and reverberation chamber).

  3. On the electric activity of superfluid helium at the excitation of first and second sound waves

    SciTech Connect

    Pashitskii, E. A. Gurin, A. A.

    2010-01-15

    We show that the electric activity of superfluid helium (HeII) observed in the experiments [3] during the excitation of standing second sound waves in an acoustic resonator can be described in terms of the phenomenological mechanism of the inertial polarization of atoms in a dielectric, in particular, in HeII, when the polarization field induced in the medium is proportional to the mechanical acceleration, by analogy with the Stewart-Tolman effect. The variable relative velocity w = v{sub n} - v{sub s} of the normal and superfluid HeII components that emerges in the second sound wave determines the mean group velocity of rotons, V{sub g} Almost-Equal-To w, with the density of the normal component related to their equilibrium number density in the temperature range 1.3 K {<=} T {<=} 2 K. Therefore, the acceleration of the 4He atoms involved in the formation of a roton excitation is proportional to the time derivative of the relative velocity.w. In this case, the linear local relations between the variable values of the electric induction, electric field strength, and polarization vector should be taken into account. As a result, the variable displacement current induced in the bulk of HeII and the corresponding potential difference do not depend on the anomalously low polarizability of liquid helium. This allows the ratio of the amplitudes of the temperature and potential oscillations in the second sound wave, which is almost independent of T in the above temperature range, consistent with experimental data to be obtained. At the same time, the absence of an electric response during the excitation of first sound waves in the linear regime is related to an insufficient power of the sound oscillations. Based on the experimental data on the excitation of first and second sounds, we have obtained estimates for the phenomenological coefficient of proportionality between the polarization vector and acceleration and for the drag coefficient of helium atoms by rotons in the

  4. The Impact of Sound on Electroencephalographic Waves during Sleep in Patients Suffering from Tinnitus.

    PubMed

    Pedemonte, Marisa; Testa, Martín; Díaz, Marcela; Suárez-Bagnasco, Diego

    2014-09-01

    Based on the knowledge that sensory processing continues during sleep and that a relationship exists between sleep and learning, a new strategy for treatment of idiopathic subjective tinnitus, consisted of customized sound stimulation presented during sleep, was tested. It has been previously shown that this treatment induces a sustained decrease in tinnitus intensity; however, its effect on brain activity has not yet been studied. In this work, we compared the impact of sound stimulation in tinnitus patients in the different sleep stages. Ten patients with idiopathic tinnitus were treated with sound stimulation mimicking tinnitus during sleep. Power spectra and intra- and inter-hemispheric coherence of electroencephalographic waves from frontal and temporal electrodes were measured with and without sound stimulation for each sleep stage (stages N2 with sleep spindles; N3 with slow wave sleep and REM sleep with Rapid Eye Movements). The main results found were that the largest number of changes, considering both the power spectrum and wave׳s coherence, occurred in stages N2 and N3. The delta and theta bands were the most changed, with important changes also in coherence of spindles during N2. All changes were more frequent in temporal areas. The differences between the two hemispheres do not depend, at least exclusively, on the side where the tinnitus is perceived and, hence, of the stimulated side. These results demonstrate that sound stimulation during sleep in tinnitus patients׳ influences brain activity and open an avenue for investigating the mechanism underlying tinnitus and its treatment.

  5. Relativistic electromagnetic waves in an electron-ion plasma

    NASA Technical Reports Server (NTRS)

    Chian, Abraham C.-L.; Kennel, Charles F.

    1987-01-01

    High power laser beams can drive plasma particles to relativistic energies. An accurate description of strong waves requires the inclusion of ion dynamics in the analysis. The equations governing the propagation of relativistic electromagnetic waves in a cold electron-ion plasma can be reduced to two equations expressing conservation of energy-momentum of the system. The two conservation constants are functions of the plasma stream velocity, the wave velocity, the wave amplitude, and the electron-ion mass ratio. The dynamic parameter, expressing electron-ion momentum conversation in the laboratory frame, can be regarded as an adjustable quantity, a suitable choice of which will yield self-consistent solutions when other plasma parameters were specified. Circularly polarized electromagnetic waves and electrostatic plasma waves are used as illustrations.

  6. Ion-acoustic cnoidal waves in a quantum plasma

    SciTech Connect

    Mahmood, S.; Haas, F.

    2014-10-15

    Nonlinear ion-acoustic cnoidal wave structures are studied in an unmagnetized quantum plasma. Using the reductive perturbation method, a Korteweg-de Vries equation is derived for appropriate boundary conditions and nonlinear periodic wave solutions are obtained. The corresponding analytical solution and numerical plots of the ion-acoustic cnoidal waves and solitons in the phase plane are presented using the Sagdeev pseudo-potential approach. The variations in the nonlinear potential of the ion-acoustic cnoidal waves are studied at different values of quantum parameter H{sub e} which is the ratio of electron plasmon energy to electron Fermi energy defined for degenerate electrons. It is found that both compressive and rarefactive ion-acoustic cnoidal wave structures are formed depending on the value of the quantum parameter. The dependence of the wavelength and frequency on nonlinear wave amplitude is also presented.

  7. Tracking kidney stones with sound during shock wave lithotripsy

    NASA Astrophysics Data System (ADS)

    Kracht, Jonathan M.

    The prevalence of kidney stones has increased significantly over the past decades. One of the primary treatments for kidney stones is shock wave lithotripsy which focuses acoustic shock waves onto the stone in order to fragment it into pieces that are small enough to pass naturally. This typically requires a few thousand shock waves delivered at a rate of about 2 Hz. Although lithotripsy is the only non-invasive treatment option for kidney stories, both acute and chronic complications have been identified which could be reduced if fewer shock waves were used. One factor that could be used to reduce the number of shock waves is accounting for the motion of the stone which causes a portion of the delivered shock waves to miss the stone, yielding no therapeutic benefit. Therefore identifying when the stone is not in focus would allow tissue to be spared without affecting fragmentation. The goal of this thesis is to investigate acoustic methods to track the stone in real-time during lithotripsy in order to minimize poorly-targeted shock waves. A relatively small number of low frequency ultrasound transducers were used in pulse-echo mode and a novel optimization routine based on time-of-flight triangulation is used to determine stone location. It was shown that the accuracy of the localization may be estimated without knowing the true stone location. This method performed well in preliminary experiments but the inclusion of tissue-like aberrating layers reduced the accuracy of the localization. Therefore a hybrid imaging technique employing DORT (Decomposition of the Time Reversal Operator) and the MUSIC (Multiple Signal Classification) algorithm was developed. This method was able to localize kidney stories to within a few millimeters even in the presence of an aberrating layer. This would be sufficient accuracy for targeting lithotripter shock waves. The conclusion of this work is that tracking kidney stones with low frequency ultrasound should be effective clinically.

  8. Strongly driven ion acoustic waves in laser produced plasmas

    SciTech Connect

    Baldis, H.A.; Labaune, C.; Renard, N.

    1994-09-20

    This paper present an experimental study of ion acoustic waves with wavenumbers corresponding to stimulated Brillouin scattering. Time resolved Thomson scattering in frequency and wavenumber space, has permitted to observe the dispersion relation of the waves as a function of the laser intensity. Apart from observing ion acoustic waves associated with a strong second component is observed at laser intensities above 10{sup 13}Wcm{sup {minus}2}.

  9. Observation of sound focusing and defocusing due to propagating nonlinear internal waves.

    PubMed

    Luo, J; Badiey, M; Karjadi, E A; Katsnelson, B; Tskhoidze, A; Lynch, J F; Moum, J N

    2008-09-01

    Fluctuations of the low frequency sound field in the presence of an internal solitary wave packet during the Shallow Water '06 experiment are analyzed. Acoustic, environmental, and on-board ship radar image data were collected simultaneously before, during, and after a strong internal solitary wave packet passed through the acoustic track. Preliminary analysis of the acoustic wave temporal intensity fluctuations agrees with previously observed phenomena and the existing theory of the horizontal refraction mechanism, which causes focusing and defocusing when the acoustic track is nearly parallel to the front of the internal waves [J. Acoust. Soc. Am., 122(2), pp. 747-760 (2007)].

  10. Self-focusing of ion-acoustic surface waves

    NASA Astrophysics Data System (ADS)

    Stenflo, L.; Gradov, O. M.

    1996-06-01

    An electrostatic ion-acoustic surface wave propagating along the boundary of a semi-infinite plasma is considered. It is shown that a nonlinear Schrödinger equation can describe the development of the wave amplitude. The self-focusing length of a wave beam is estimated.

  11. Efficient techniques for wave-based sound propagation in interactive applications

    NASA Astrophysics Data System (ADS)

    Mehra, Ravish

    Sound propagation techniques model the effect of the environment on sound waves and predict their behavior from point of emission at the source to the final point of arrival at the listener. Sound is a pressure wave produced by mechanical vibration of a surface that propagates through a medium such as air or water, and the problem of sound propagation can be formulated mathematically as a second-order partial differential equation called the wave equation. Accurate techniques based on solving the wave equation, also called the wave-based techniques, are too expensive computationally and memory-wise. Therefore, these techniques face many challenges in terms of their applicability in interactive applications including sound propagation in large environments, time-varying source and listener directivity, and high simulation cost for mid-frequencies. In this dissertation, we propose a set of efficient wave-based sound propagation techniques that solve these three challenges and enable the use of wave-based sound propagation in interactive applications. Firstly, we propose a novel equivalent source technique for interactive wave-based sound propagation in large scenes spanning hundreds of meters. It is based on the equivalent source theory used for solving radiation and scattering problems in acoustics and electromagnetics. Instead of using a volumetric or surface-based approach, this technique takes an object-centric approach to sound propagation. The proposed equivalent source technique generates realistic acoustic effects and takes orders of magnitude less runtime memory compared to prior wave-based techniques. Secondly, we present an efficient framework for handling time-varying source and listener directivity for interactive wave-based sound propagation. The source directivity is represented as a linear combination of elementary spherical harmonic sources. This spherical harmonic-based representation of source directivity can support analytical, data

  12. Inferring Magnetospheric Heavy Ion Density using EMIC Waves

    SciTech Connect

    Kim, Eun-Hwa; Johnson, Jay R.; Kim, Hyomin; Lee, Dong-Hun

    2014-05-01

    We present a method to infer heavy ion concentration ratios from EMIC wave observations that result from ionion hybrid (IIH) resonance. A key feature of the ion-ion hybrid resonance is the concentration of wave energy in a field-aligned resonant mode that exhibits linear polarization. This mode converted wave is localized at the location where the frequency of a compressional wave driver matches the IIH resonance condition, which depends sensitively on the heavy ion concentration. This dependence makes it possible to estimate the heavy ion concentration ratio. In this letter, we evaluate the absorption coefficients at the IIH resonance at Earth's geosynchronous orbit for variable concentrations of He+ and field-aligned wave numbers using a dipole magnetic field. Although wave absorption occurs for a wide range of heavy ion concentrations, it only occurs for a limited range of field-aligned wave numbers such that the IIH resonance frequency is close to, but not exactly the same as the crossover frequency. Using the wave absorption and observed EMIC waves from GOES-12 satellite, we demonstrate how this technique can be used to estimate that the He+ concentration is around 4% near L = 6.6.

  13. Sound Wave Energy Resulting from the Impact of Water Drops on the Soil Surface.

    PubMed

    Ryżak, Magdalena; Bieganowski, Andrzej; Korbiel, Tomasz

    2016-01-01

    The splashing of water drops on a soil surface is the first step of water erosion. There have been many investigations into splashing-most are based on recording and analysing images taken with high-speed cameras, or measuring the mass of the soil moved by splashing. Here, we present a new aspect of the splash phenomenon's characterization the measurement of the sound pressure level and the sound energy of the wave that propagates in the air. The measurements were carried out for 10 consecutive water drop impacts on the soil surface. Three soils were tested (Endogleyic Umbrisol, Fluvic Endogleyic Cambisol and Haplic Chernozem) with four initial moisture levels (pressure heads: 0.1 kPa, 1 kPa, 3.16 kPa and 16 kPa). We found that the values of the sound pressure and sound wave energy were dependent on the particle size distribution of the soil, less dependent on the initial pressure head, and practically the same for subsequent water drops (from the first to the tenth drop). The highest sound pressure level (and the greatest variability) was for Endogleyic Umbrisol, which had the highest sand fraction content. The sound pressure for this soil increased from 29 dB to 42 dB with the next incidence of drops falling on the sample The smallest (and the lowest variability) was for Fluvic Endogleyic Cambisol which had the highest clay fraction. For all experiments the sound pressure level ranged from ~27 to ~42 dB and the energy emitted in the form of sound waves was within the range of 0.14 μJ to 5.26 μJ. This was from 0.03 to 1.07% of the energy of the incident drops.

  14. Sound Wave Energy Resulting from the Impact of Water Drops on the Soil Surface

    PubMed Central

    Ryżak, Magdalena; Bieganowski, Andrzej; Korbiel, Tomasz

    2016-01-01

    The splashing of water drops on a soil surface is the first step of water erosion. There have been many investigations into splashing–most are based on recording and analysing images taken with high-speed cameras, or measuring the mass of the soil moved by splashing. Here, we present a new aspect of the splash phenomenon’s characterization the measurement of the sound pressure level and the sound energy of the wave that propagates in the air. The measurements were carried out for 10 consecutive water drop impacts on the soil surface. Three soils were tested (Endogleyic Umbrisol, Fluvic Endogleyic Cambisol and Haplic Chernozem) with four initial moisture levels (pressure heads: 0.1 kPa, 1 kPa, 3.16 kPa and 16 kPa). We found that the values of the sound pressure and sound wave energy were dependent on the particle size distribution of the soil, less dependent on the initial pressure head, and practically the same for subsequent water drops (from the first to the tenth drop). The highest sound pressure level (and the greatest variability) was for Endogleyic Umbrisol, which had the highest sand fraction content. The sound pressure for this soil increased from 29 dB to 42 dB with the next incidence of drops falling on the sample The smallest (and the lowest variability) was for Fluvic Endogleyic Cambisol which had the highest clay fraction. For all experiments the sound pressure level ranged from ~27 to ~42 dB and the energy emitted in the form of sound waves was within the range of 0.14 μJ to 5.26 μJ. This was from 0.03 to 1.07% of the energy of the incident drops. PMID:27388276

  15. Propagation of sound waves in tubes of noncircular cross section

    NASA Technical Reports Server (NTRS)

    Richards, W. B.

    1986-01-01

    Plane-acoustic-wave propagation in small tubes with a cross section in the shape of a flattened oval is described. Theoretical descriptions of a plane wave propagating in a tube with circular cross section and between a pair of infinite parallel plates, including viscous and thermal damping, are expressed in similar form. For a wide range of useful duct sizes, the propagation constant (whose real and imaginary parts are the amplitude attenuation rate and the wave number, respectively) is very nearly the same function of frequency for both cases if the radius of the circular tube is the same as the distance between the parallel plates. This suggests that either a circular-cross-section model or a flat-plate model can be used to calculate wave propagation in flat-oval tubing, or any other shape tubing, if its size is expressed in terms of an equivalent radius, given by g = 2 x (cross-sectional area)/(length of perimeter). Measurements of the frequency response of two sections of flat-oval tubing agree with calculations based on this idea. Flat-plate formulas are derived, the use of transmission-line matrices for calculations of plane waves in compound systems of ducts is described, and examples of computer programs written to carry out the calculations are shown.

  16. Wave tilt sounding of multilayered structures. [for probing of stratified planetary surface electrical properties and thickness

    NASA Technical Reports Server (NTRS)

    Warne, L.; Jaggard, D. L.; Elachi, C.

    1979-01-01

    The relationship between the wave tilt and the electrical parameters of a multilayered structure is investigated. Particular emphasis is placed on the inverse problem associated with the sounding planetary surfaces. An inversion technique, based on multifrequency wave tilt, is proposed and demonstrated with several computer models. It is determined that there is close agreement between the electrical parameters used in the models and those in the inversion values.

  17. Visualization and Measurements of Sound Pressure Distribution of Ultrasonic Wave by Stroboscopic Real-Time Holographic Interferometry

    NASA Astrophysics Data System (ADS)

    Hisada, Shigeyoshi; Suzuki, Takahiro; Nakahara, Sumio; Fujita, Takeyoshi

    2002-05-01

    The sound pressure distribution of underwater ultrasonic waves is measured by real-time stroboscope holographic interferometry using bismuth silicon oxide single crystal. Stroboscopic sub-microsecond irradiation of laser light enables the recording of the stationary holographic interferogram of refractive index changes of water by ultrasonic waves for the frame time of a charge coupled device camera. The fringe order distribution is calculated from the interferogram by Fourier transform fringe analysis. The optical path differences caused by sound field along the optical path are converted into local field values of sound pressure, which is displayed as a gray scale distribution image. In the experiment, the sound pressure distributions of ultrasonic waves through rectangular and circular apertures are observed. They are compared with the theoretical sound pressure distribution. The sound pressure values obtained by a hydrophone show good agreement with the measured values obtained by this method. The converging and diverging sound pressure fields realized by an acoustic lens are measured.

  18. CRRES observations of ion composition during EMIC mode wave events

    SciTech Connect

    Macdonald, Elizabeth; Larsen, Brian

    2010-12-13

    EMIC mode waves may play an important role in the dynamics of the growth and loss of the radiation belts. CRRES mission analysis has provided extensive information on the distributions of EMIC mode waves. Less well studied and understood is the role that ion composition plays in the formation of the EMIC mode waves. The CRESS plasma mass spectrometer LOMICS measured all ion species of interest up to 45 keV/q. This preliminary study will examine the characteristics of heavy ions during a multitude of wave events, in particular, the effect of ion composition on wave-particle interactions, amplitude, and frequency. The relevance of such data to the upcoming RBSP mission will be highlighted.

  19. Stochastic Acceleration of Ions Driven by Pc1 Wave Packets

    NASA Technical Reports Server (NTRS)

    Khazanov, G. V.; Sibeck, D. G.; Tel'nikhin, A. A.; Kronberg, T. K.

    2015-01-01

    The stochastic motion of protons and He(sup +) ions driven by Pc1 wave packets is studied in the context of resonant particle heating. Resonant ion cyclotron heating typically occurs when wave powers exceed 10(exp -4) nT sq/Hz. Gyroresonance breaks the first adiabatic invariant and energizes keV ions. Cherenkov resonances with the electrostatic component of wave packets can also accelerate ions. The main effect of this interaction is to accelerate thermal protons to the local Alfven speed. The dependencies of observable quantities on the wave power and plasma parameters are determined, and estimates for the heating extent and rate of particle heating in these wave-particle interactions are shown to be in reasonable agreement with known empirical data.

  20. Stochastic acceleration of ions driven by Pc1 wave packets

    SciTech Connect

    Khazanov, G. V. Sibeck, D. G.; Tel'nikhin, A. A.; Kronberg, T. K.

    2015-07-15

    The stochastic motion of protons and He{sup +} ions driven by Pc1 wave packets is studied in the context of resonant particle heating. Resonant ion cyclotron heating typically occurs when wave powers exceed 10{sup −4} nT{sup 2}/Hz. Gyroresonance breaks the first adiabatic invariant and energizes keV ions. Cherenkov resonances with the electrostatic component of wave packets can also accelerate ions. The main effect of this interaction is to accelerate thermal protons to the local Alfven speed. The dependencies of observable quantities on the wave power and plasma parameters are determined, and estimates for the heating extent and rate of particle heating in these wave-particle interactions are shown to be in reasonable agreement with known empirical data.

  1. Horizontal ducting of sound by curved nonlinear internal gravity waves in the continental shelf areas.

    PubMed

    Lin, Ying-Tsong; McMahon, Kara G; Lynch, James F; Siegmann, William L

    2013-01-01

    The acoustic ducting effect by curved nonlinear gravity waves in shallow water is studied through idealized models in this paper. The internal wave ducts are three-dimensional, bounded vertically by the sea surface and bottom, and horizontally by aligned wavefronts. Both normal mode and parabolic equation methods are taken to analyze the ducted sound field. Two types of horizontal acoustic modes can be found in the curved internal wave duct. One is a whispering-gallery type formed by the sound energy trapped along the outer and concave boundary of the duct, and the other is a fully bouncing type due to continual reflections from boundaries in the duct. The ducting condition depends on both internal-wave and acoustic-source parameters, and a parametric study is conducted to derive a general pattern. The parabolic equation method provides full-field modeling of the sound field, so it includes other acoustic effects caused by internal waves, such as mode coupling/scattering and horizontal Lloyd's mirror interference. Two examples are provided to present internal wave ducts with constant curvature and meandering wavefronts.

  2. Schlieren imaging of loud sounds and weak shock waves in air near the limit of visibility

    NASA Astrophysics Data System (ADS)

    Hargather, Michael John; Settles, Gary S.; Madalis, Matthew J.

    2010-02-01

    A large schlieren system with exceptional sensitivity and a high-speed digital camera are used to visualize loud sounds and a variety of common phenomena that produce weak shock waves in the atmosphere. Frame rates varied from 10,000 to 30,000 frames/s with microsecond frame exposures. Sound waves become visible to this instrumentation at frequencies above 10 kHz and sound pressure levels in the 110 dB (6.3 Pa) range and above. The density gradient produced by a weak shock wave is examined and found to depend upon the profile and thickness of the shock as well as the density difference across it. Schlieren visualizations of weak shock waves from common phenomena include loud trumpet notes, various impact phenomena that compress a bubble of air, bursting a toy balloon, popping a champagne cork, snapping a wooden stick, and snapping a wet towel. The balloon burst, snapping a ruler on a table, and snapping the towel and a leather belt all produced readily visible shock-wave phenomena. In contrast, clapping the hands, snapping the stick, and the champagne cork all produced wave trains that were near the weak limit of visibility. Overall, with sensitive optics and a modern high-speed camera, many nonlinear acoustic phenomena in the air can be observed and studied.

  3. Analog of Optical Elements for Sound Waves in Air

    ERIC Educational Resources Information Center

    Gluck, Paul; Perkalskis, Benjamin

    2009-01-01

    Optical elements manipulate light waves. They may be used to focus the light or to change the phase, the polarization, the direction, or the intensity of light. Many of these functions are often demonstrated with microwaves, since the devices normally available in teaching laboratories produce wavelengths in the centimeter range and are therefore…

  4. Softening of stressed granular packings with resonant sound waves.

    PubMed

    Reichhardt, C J Olson; Lopatina, L M; Jia, X; Johnson, P A

    2015-08-01

    We perform numerical simulations of a two-dimensional bidisperse granular packing subjected to both a static confining pressure and a sinusoidal dynamic forcing applied by a wall on one edge of the packing. We measure the response experienced by a wall on the opposite edge of the packing and obtain the resonant frequency of the packing as the static or dynamic pressures are varied. Under increasing static pressure, the resonant frequency increases, indicating a velocity increase of elastic waves propagating through the packing. In contrast, when the dynamic amplitude is increased for fixed static pressure, the resonant frequency decreases, indicating a decrease in the wave velocity. This occurs both for compressional and for shear dynamic forcing and is in agreement with experimental results. We find that the average contact number Zc at the resonant frequency decreases with increasing dynamic amplitude, indicating that the elastic softening of the packing is associated with a reduced number of grain-grain contacts through which the elastic waves can travel. We image the excitations created in the packing and show that there are localized disturbances or soft spots that become more prevalent with increasing dynamic amplitude. Our results are in agreement with experiments on glass bead packings and earth materials such as sandstone and granite and may be relevant to the decrease in elastic wave velocities that has been observed to occur near fault zones after strong earthquakes, in surficial sediments during strong ground motion, and in structures during earthquake excitation.

  5. Illustrations and Supporting Texts for Sound Standing Waves of Air Columns in Pipes in Introductory Physics Textbooks

    ERIC Educational Resources Information Center

    Zeng, Liang; Smith, Chris; Poelzer, G. Herold; Rodriguez, Jennifer; Corpuz, Edgar; Yanev, George

    2014-01-01

    In our pilot studies, we found that many introductory physics textbook illustrations with supporting text for sound standing waves of air columns in open-open, open-closed, and closed-closed pipes inhibit student understanding of sound standing wave phenomena due to student misunderstanding of how air molecules move within these pipes. Based on…

  6. Mode conversion of fast Alfvén waves at the ion-ion hybrid resonance

    NASA Astrophysics Data System (ADS)

    Ram, A. K.; Bers, A.; Schultz, S. D.; Fuchs, V.

    1996-05-01

    Substantial radio-frequency power in the ion-cyclotron range of frequencies can be effectively coupled to a tokamak plasma from poloidal current strap antennas at the plasma edge. If there exists an ion-ion hybrid resonance inside the plasma, then some of the power from the antenna, delivered into the plasma by fast Alfvén waves, can be mode converted to ion-Bernstein waves. In tokamak confinement fields the mode-converted ion-Bernstein waves can damp effectively and locally on electrons [A. K. Ram and A. Bers, Phys. Fluids B 3, 1059 (1991)]. The usual mode-conversion analysis that studies the propagation of fast Alfvén waves in the immediate vicinity of the ion-ion hybrid resonance is extended to include the propagation and reflection of the fast Alfvén waves on the high magnetic-field side of the ion-ion hybrid resonance. It is shown that there exist plasma conditions for which the entire fast Alfvén wave power incident on the ion-ion hybrid resonance can be converted to ion-Bernstein waves. In this extended analysis of the mode conversion process, the fast Alfvén waves can be envisioned as being coupled to an internal plasma resonator. This resonator extends from the low magnetic-field cutoff near the ion-ion hybrid resonance to the high magnetic-field cutoff. The condition for 100% mode conversion corresponds to a critical coupling of the fast Alfvén waves to this internal resonator. As an example, the appropriate plasma conditions for 100% mode conversion are determined for the Tokamak Fusion Test Reactor (TFTR) [R. Majeski et al., Proceedings of the 11th Topical Conference on RF Power in Plasmas, Palm Springs (American Institute of Physics, New York, 1995), Vol. 355, p. 63] experimental parameters.

  7. Inferring magnetospheric heavy ion density using EMIC waves

    NASA Astrophysics Data System (ADS)

    Kim, Eun-Hwa; Johnson, Jay R.; Kim, Hyomin; Lee, Dong-Hun

    2015-08-01

    We present a method to infer heavy ion concentration ratios from electromagnetic ion cyclotron (EMIC) wave observations that result from ion-ion hybrid (IIH) resonance. A key feature of the IIH resonance is the concentration of wave energy in a field-aligned resonant mode that exhibits linear polarization. These mode-converted waves at the IIH resonance are localized at the location where the frequency of a compressional wave driver matches the IIH resonance condition, which depends sensitively on the heavy ion concentration. This dependence makes it possible to estimate the heavy ion concentration ratio. In this paper, we evaluate the absorption coefficients at the IIH resonance at Earth's geosynchronous orbit for variable concentrations of He+ and wave frequencies using a dipole magnetic field model. We find that the resonance only occurs over a limited range of wave frequency such that the IIH resonance frequency is close to but not exactly the same as the crossover frequency. Using the wave absorption and EMIC waves observed from the GOES 12 satellite, we demonstrate how this technique can be used to estimate the He+ concentration of around 4% near L = 6.6 assuming electron-H+-He+ plasma.

  8. Deltas, freshwater discharge, and waves along the Young Sound, NE Greenland.

    PubMed

    Kroon, Aart; Abermann, Jakob; Bendixen, Mette; Lund, Magnus; Sigsgaard, Charlotte; Skov, Kirstine; Hansen, Birger Ulf

    2017-02-01

    A wide range of delta morphologies occurs along the fringes of the Young Sound in Northeast Greenland due to spatial heterogeneity of delta regimes. In general, the delta regime is related to catchment and basin characteristics (geology, topography, drainage pattern, sediment availability, and bathymetry), fluvial discharges and associated sediment load, and processes by waves and currents. Main factors steering the Arctic fluvial discharges into the Young Sound are the snow and ice melt and precipitation in the catchment, and extreme events like glacier lake outburst floods (GLOFs). Waves are subordinate and only rework fringes of the delta plain forming sandy bars if the exposure and fetch are optimal. Spatial gradients and variability in driving forces (snow and precipitation) and catchment characteristics (amount of glacier coverage, sediment characteristics) as well as the strong and local influence of GLOFs in a specific catchment impede a simple upscaling of sediment fluxes from individual catchments toward a total sediment flux into the Young Sound.

  9. Amplification of sound waves in an imploding plasma shell: Exact results

    SciTech Connect

    Han, S.J.

    1988-01-01

    In an extended model, a rigorous proof is given for sound-wave amplifications in an imploding plasma shell. It is shown that, in the absence of a massless free surface, the boundary conditions give the exact eigenvalues which determine the asymptotic solution to the problem.

  10. Suggested Courseware for the Non-Calculus Physics Student: Simple Harmonic Motion, Wave Motion, and Sound.

    ERIC Educational Resources Information Center

    Grable-Wallace, Lisa; And Others

    1989-01-01

    Evaluates 5 courseware packages covering the topics of simple harmonic motion, 7 packages for wave motion, and 10 packages for sound. Discusses the price range, sub-topics, program type, interaction, time, calculus required, graphics, and comments of each courseware. Selects several packages based on the criteria. (YP)

  11. Numerical study of three-dimensional sound reflection from corrugated surface waves.

    PubMed

    Choo, Youngmin; Song, H C; Seong, Woojae

    2016-10-01

    When a sound wave propagates in a water medium bounded by a smooth surface wave, reflection from a wave crest can lead to focusing and result in rapid variation of the received waveform as the surface wave moves [Tindle, Deane, and Preisig, J. Acoust. Soc. Am. 125, 66-72 (2009)]. In prior work, propagation paths have been constrained to be in a plane parallel to the direction of corrugated surface waves, i.e., a two-dimensional (2-D) propagation problem. In this paper, the azimuthal dependence of sound propagation as a three-dimensional (3-D) problem is investigated using an efficient, time-domain Helmholtz-Kirchhoff integral formulation. When the source and receiver are in the plane orthogonal to the surface wave direction, the surface wave curvature vanishes in conventional 2-D treatments and the flat surface simply moves up and down, resulting in minimal temporal variation of the reflected signal intensity. On the other hand, the 3-D propagation analysis reveals that a focusing phenomenon occurs in the reflected signal due to the surface wave curvature formed along the orthogonal plane, i.e., out-of-plane scattering.

  12. Acoustofluidics 15: streaming with sound waves interacting with solid particles.

    PubMed

    Sadhal, S S

    2012-08-07

    In Part 15 of the tutorial series "Acoustofluidics-exploiting ultrasonic standing waves forces and acoustic streaming in microfluidic systems for cell and particle manipulation," we examine the interaction of acoustic fields with solid particles. The main focus here is the interaction of standing waves with spherical particles leading to streaming, together with some discussion on one non-spherical case. We begin with the classical problem of a particle at the velocity antinode of a standing wave, and then treat the problem of a sphere at the velocity node, followed by the intermediate situation of a particle between nodes. Finally, we discuss the effect of deviation from sphericity which brings about interesting fluid mechanics. The entire Focus article is devoted to the analysis of the nonlinear fluid mechanics by singular perturbation methods, and the study of the streaming phenomenon that ensues from the nonlinear interaction. With the intention of being instructive material, this tutorial cannot by any means be considered 'complete and comprehensive' owing to the complexity of the class of problems being covered herein.

  13. Mode identification of whistler mode, Z-mode, and Langmuir/Upper Hybrid mode waves observed in an auroral sounding rocket experiment

    NASA Astrophysics Data System (ADS)

    Colpitts, C. A.; Labelle, J.

    2008-04-01

    The SIERRA (Sounding of the Ion Energization Region - Resolving Ambiguities) rocket was launched to 735 km over an active auroral substorm from Poker Flat, Alaska, on 14 January 2002. A wealth of wave modes at frequencies from below 100 kHz to above 2000 kHz were detected with a dipole electric field antenna that was alternately parallel and perpendicular to Earth's magnetic field. At least two types of whistler mode waves were detected: unstructured broadband whistler waves commonly referred to as auroral hiss occurring at frequencies from <100 kHz up to 1000 kHz, and structured narrowband features in the whistler mode at frequencies of 100 kHz to 600 kHz (Samara and LaBelle, 2006a). Other waves detected in the frequency range 1200 to 2000 kHz were interpreted as Langmuir-upper hybrid waves and Z-mode waves. For the unstructured whistler mode waves, comparison of the observed spin dependence of the wave electric fields with Monte Carlo simulations of the expected spin dependence for various polarizations suggests that these waves propagate on or near the resonance cone, which is consistent with previous measurements. Similar analyses of the presumed Langmuir and Z-mode waves show their electric fields are preferentially parallel and perpendicular to the ambient magnetic field, respectively. These characteristics, together with the relation of the wave frequencies to the Z cutoff frequency, serve to confirm the mode identification of these waves.

  14. Sound waves induce Volkov-like states, band structure and collimation effect in graphene.

    PubMed

    Oliva-Leyva, M; Naumis, Gerardo G

    2016-01-20

    We find exact states of graphene quasiparticles under a time-dependent deformation (sound wave), whose propagation velocity is smaller than the Fermi velocity. To solve the corresponding effective Dirac equation, we adapt the Volkov-like solutions for relativistic fermions in a medium under a plane electromagnetic wave. The corresponding electron-deformation quasiparticle spectrum is determined by the solutions of a Mathieu equation resulting in band tongues warped in the surface of the Dirac cones. This leads to a collimation effect of electron conduction due to strain waves.

  15. Magnetosonic wave in pair-ion electron collisional plasmas

    NASA Astrophysics Data System (ADS)

    Hussain, S.; Hasnain, H.

    2017-03-01

    Low frequency magnetosonic waves in positive and negative ions of equal mass and opposite charges in the presence of electrons in collisional plasmas are studied. The collisions of ions and electrons with neutrals are taken into account. The nonlinearities in the plasma system arise due to ion and electrons flux, Lorentz forces, and plasma current densities. The reductive perturbation method is applied to derive the Damped Korteweg de Vries (DKdV) equation. The time dependent solution of DKdV is presented. The effects of variations of different plasma parameters on propagation characteristics of magnetosonic waves in pair-ion electron plasma in the context of laboratory plasmas are discussed.

  16. Asymptotic permanent profile of the ion acoustic wave driven by the Langmuir wave

    NASA Astrophysics Data System (ADS)

    Kaup, D. J.; Latifi, A.; Leon, J.

    1992-08-01

    We study the evolution of Langmuir waves coupled to the ion acoustic wave by means of the ponderomotive force in the Karpman limit (caviton equation). Using the spectral transform with singular dispersion relation, it is shown that the background noise (fluctuations in the ion density) is amplified and its time asymptotic behavior will be a static solution which is totally reflective for the Langmuir wave. Moreover, if the initial ion density contains a local depression, the asymptotic profile will contain a number of permanent localized density depressions (cavitons), static in the rest frame of the acoustic wave and entrained in its wake.

  17. The generation of sound by vorticity waves in swirling duct flows

    NASA Technical Reports Server (NTRS)

    Howe, M. S.; Liu, J. T. C.

    1977-01-01

    Swirling flow in an axisymmetric duct can support vorticity waves propagating parallel to the axis of the duct. When the cross-sectional area of the duct changes a portion of the wave energy is scattered into secondary vorticity and sound waves. Thus the swirling flow in the jet pipe of an aeroengine provides a mechanism whereby disturbances produced by unsteady combustion or turbine blading can be propagated along the pipe and subsequently scattered into aerodynamic sound. In this paper a linearized model of this process is examined for low Mach number swirling flow in a duct of infinite extent. It is shown that the amplitude of the scattered acoustic pressure waves is proportional to the product of the characteristic swirl velocity and the perturbation velocity of the vorticity wave. The sound produced in this way may therefore be of more significance than that generated by vorticity fluctuations in the absence of swirl, for which the acoustic pressure is proportional to the square of the perturbation velocity. The results of the analysis are discussed in relation to the problem of excess jet noise.

  18. NEW APPROACHES: The Doppler effect: a unified approach for sound and light waves

    NASA Astrophysics Data System (ADS)

    Gupta, O. P.

    1996-11-01

    A derivation of the Doppler effect is presented where the analysis of the Doppler shift for sound is the same as for electromagnetic waves (in vacuum). Furthermore, for sound waves the treatment is the same no matter whether only the sounce (S) is moving (with respect to the medium), or only the observer (O), or both S and O. The analysis shows clearly that the basic cause of the Doppler shift is the relative velocity between S and O in all cases, and not just for electromagnetic waves (where individual velocities of S and O are not even definable). The difference in the expressions for the Doppler shift in different cases is due to other factors which are easy to understand.

  19. Rogue wave triplets in an ion-beam dusty plasma with superthermal electrons and negative ions

    NASA Astrophysics Data System (ADS)

    Guo, Shimin; Mei, Liquan; Shi, Weijuan

    2013-11-01

    A new dust ion-acoustic wave structure called ‘Rogue wave triplets’ is investigated in an unmagnetized plasma consisting of stationary negatively charged dust grains, charged positive and negative ions, and electrons obeying kappa distribution, which is penetrated by an ion beam. The reductive perturbation theory is used to derive the nonlinear Schrödinger equation governing the dynamics as well as the modulation of wave packets. The rogue wave triplets which are composed of three separate Peregrine breathers can be generated in the modulation instability region. It has been suggested that a laboratory experiment be performed to test the theory presented here.

  20. Application of the Wave and Finite Element Method to Calculate Sound Transmission Through Cylindrical Structures

    NASA Astrophysics Data System (ADS)

    Kingan, Michael J.; Yang, Yi; Mace, Brian R.

    2016-09-01

    This paper concerns the prediction of sound transmission through a cylindrical structure. The problem considered is that of sound generated by a line source located exterior to a two-dimensional circular cylinder which produces sound waves which transmit through the cylinder to an internal medium. An analytical solution is presented for the case of sound transmission through a thin cylindrical shell, by modelling the shell response using the Flugge- Byrne-Lur'ye equations. This solution is then compared to calculations where the response of the cylinder is calculated using the Wave and Finite Element (WFE) method. The WFE method involves modelling a small segment of a structure using traditional finite element (FE) methods. The mass and stiffness matrices of the segment are then used to calculate the response of the structure to excitation by an acoustic field. The WFE approach for calculating sound transmission is validated by comparison with the analytic solution. Formulating analytic solutions for more complicated structures can be cumbersome whereas using a numerical technique, such as the WFE method, is relatively straightforward.

  1. Outgoing long-wave radiation computed from HIRS2/MSU soundings. [High InfraRed Spectrometer/Microwave Sounding Unit

    SciTech Connect

    Wu, M.C.; Susskind, J. )

    1990-05-20

    Fields of outgoing long-wave radiation (OLR) have been computed using geophysical parameters retrieved from analysis of HIRS2/MSU sounding data as input to a modified version of the Wu-Kaplan radiation code used in the Goddard Laboratory for Atmospheres fourth-order general circulation model. Monthly mean results for 1979 agree with monthly mean OLR fields measured by the Nimbus 7 Earth radiation budget (ERB) broadband narrow field of view instrument within standard deviations of 6.3 W/m{sup 2} but with a global mean bias of 8.0 W/m{sup 2}. Results are shown for July 1979. The areas of disagreement between high-resolution infrared radiation sounder OLR and ERB OLR are small but spatially coherent with patterns which may be related to sampling differences. The difference patterns are much less extensive than those between OLR derived from advanced very high resolution radiometer 11-{mu}m observations and ERB OLR. The ability to compute OLR from geophysical parameters is complementary to direct measurement of OLR because it enables one to attribute changes in OLR in space and time to changes in other geophysical parameters. In addition, it allows one to compute fields not directly measurable from satellite, such as the difference of the upward long-wave flux between the surface and the top of the atmosphere and the long-wave cloud radiative forcing.

  2. A wave field synthesis approach to reproduction of spatially correlated sound fields.

    PubMed

    Berry, Alain; Dia, Rokhiya; Robin, Olivier

    2012-02-01

    This article discusses an open-loop wave field synthesis (WFS) approach for the reproduction of spatially correlated sound fields. The main application concerns laboratory reproduction of turbulent boundary layer wall pressure on aircraft fuselages and measurement of their sound transmission loss. The problem configuration involves reconstruction of random sound pressure distributions on a planar reproduction surface using a planar array of reproduction monopoles parallel to the reproduction plane. In this paper, the WFS formulation is extended to sound fields with imposed time and spatial correlation properties (or equivalently imposed cross-spectral density in the frequency and wave number domains). Numerical examples are presented for the reproduction of a propagating plane wave, diffuse acoustic field and wall pressure in subsonic or supersonic turbulent boundary layers. The reproduction accuracy is examined in terms of the size of the source plane and reproduction plane, their separation, and the number of reproduction sources required per acoustic wavelength. While the reproduction approach cannot reconstruct sub-wavelength correlation scales of subsonic turbulent boundary layers, it effectively reconstructs correlation scales larger than the acoustic wavelength, making it appropriate for diffuse acoustic field and supersonic turbulent layers.

  3. Analysis of sound propagation in ducts using the wave envelope concept

    NASA Technical Reports Server (NTRS)

    Baumeister, K. J.

    1974-01-01

    A finite difference formulation is presented for sound propagation in a rectangular two-dimensional duct without steady flow for plane wave input. Before the difference equations are formulated, the governing Helmholtz equation is first transformed to a form whose solution does not oscillate along the length of the duct. This transformation reduces the required number of grid points by an order of magnitude, and the number of grid points becomes independent of the sound frequency. Physically, the transformed pressure represents the amplitude of the conventional sound wave. Example solutions are presented for sound propagation in a one-dimensional straight hard-wall duct and in a two-dimensional straight soft-wall duct without steady flow. The numerical solutions show evidence of the existence along the duct wall of a developing acoustic pressure diffusion boundary layer which is similar in nature to the conventional viscous flow boundary layer. In order to better illustrate this concept, the wave equation and boundary conditions are written such that the frequency no longer appears explicitly in them. The frequency effects in duct propagation can be visualized solely as an expansion and stretching of the suppressor duct.

  4. Weakly dissipative dust-ion acoustic wave modulation

    NASA Astrophysics Data System (ADS)

    Alinejad, H.; Mahdavi, M.; Shahmansouri, M.

    2016-02-01

    The modulational instability of dust-ion acoustic (DIA) waves in an unmagnetized dusty plasma is investigated in the presence of weak dissipations arising due to the low rates (compared to the ion oscillation frequency) of ionization recombination and ion loss. Based on the multiple space and time scales perturbation, a new modified nonlinear Schrödinger equation governing the evolution of modulated DIA waves is derived with a linear damping term. It is shown that the combined action of all dissipative mechanisms due to collisions between particles reveals the permitted maximum time for the occurrence of the modulational instability. The influence on the modulational instability regions of relevant physical parameters such as ion temperature, dust concentration, ionization, recombination and ion loss is numerically examined. It is also found that the recombination frequency controls the instability growth rate, whereas recombination and ion loss make the instability regions wider.

  5. Ion-neutral collision effect on an Alfven wave

    SciTech Connect

    Amagishi, Y.; Tanaka, M. Department of High Energy Engineering Science, Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, Kasuga, Fukuoka 816 )

    1993-07-19

    This paper reports that ion-neutral collisions in a magnetized plasma cause a drastic change in the dispersion relation of the shear Alfven wave with poloidal mode number [ital m]=0, connecting to the branch of the [ital m]=+1 compressional Alfven wave at frequencies below the ion-cyclotron frequency. An anomaly of the dispersion then appears on the refractive index curve and a wave packet in this frequency range undergoes strong amplitude damping and profile deformation. It is confirmed that the Kramers-Kronig relation holds for the dielectric function, estimated from both the measured refractive index and damping rate.

  6. Measured and calculated transmission losses of sound waves through a helium layer

    NASA Technical Reports Server (NTRS)

    Norum, T. D.

    1973-01-01

    An experiment was performed to measure the transmission losses of sound waves traversing an impedance layer. The sound emanated from a point source and the impedance layer was created by a low-speed helium jet. The transmission losses measured were of the order of 12 db for frequencies of the source between 4 and 12 kHz. These losses are greater than those predicted from analysis when the observer angle is less than about 35 deg, but less than those predicted for larger observer angles. The experimental results indicate that appreciable noise reductions can be realized for an observer shielded by an impedance layer, irrespective of his position relative to the source of sound.

  7. Oblique ion acoustic shock waves in a magnetized plasma

    SciTech Connect

    Shahmansouri, M.; Mamun, A. A.

    2013-08-15

    Ion acoustic (IA) shock waves are studied in a magnetized plasma consisting of a cold viscous ion fluid and Maxwellian electrons. The Korteweg–de Vries–Burgers equation is derived by using the reductive perturbation method. It is shown that the combined effects of external magnetic field and obliqueness significantly modify the basic properties (viz., amplitude, width, speed, etc.) of the IA shock waves. It is observed that the ion-viscosity is a source of dissipation, and is responsible for the formation of IA shock structures. The implications of our results in some space and laboratory plasma situations are discussed.

  8. Observation of two-dimensional classical wave localization: third sound on superfluid 4He films on a disordered substrate.

    PubMed

    Luhman, D R; Herrmann, J C; Hallock, R B

    2005-05-06

    We present the results of measurements of the propagation of third sound waves on superfluid 4He adsorbed to two-dimensional ordered and disordered substrates. In the disordered case we compare the experimental results to theoretical predictions of classical wave localization in such systems and conclude that classical wave localization is present in our system.

  9. Investigation of an ion-ion hybrid Alfvén wave resonator

    NASA Astrophysics Data System (ADS)

    Vincena, S. T.; Farmer, W. A.; Maggs, J. E.; Morales, G. J.

    2013-01-01

    A theoretical and experimental investigation is made of a wave resonator based on the concept of wave reflection along the confinement magnetic field at a spatial location where the wave frequency matches the local value of the ion-ion hybrid frequency. Such a situation can be realized by shear Alfvén waves in a magnetized plasma with two ion species because this mode has zero parallel group velocity and experiences a cut-off at the ion-ion hybrid frequency. Since the ion-ion hybrid frequency is proportional to the magnetic field, it is expected that a magnetic well configuration in a two-ion plasma can result in an Alfvén wave resonator. Such a concept has been proposed in various space plasma studies and could have relevance to mirror and tokamak fusion devices. This study demonstrates such a resonator in a controlled laboratory experiment using a H+-He+ mixture. The resonator response is investigated by launching monochromatic waves and impulses from a magnetic loop antenna. The observed frequency spectra are found to agree with predictions of a theoretical model of trapped eigenmodes.

  10. Shock wave initiated by an ion passing through liquid water

    NASA Astrophysics Data System (ADS)

    Surdutovich, Eugene; Solov'Yov, Andrey V.

    2010-11-01

    We investigate the shock wave produced by an energetic ion in liquid water. This wave is initiated by a rapid energy loss when the ion moves through the Bragg peak. The energy is transferred from the ion to secondary electrons, which then transfer it to the water molecules. The pressure in the overheated water increases by several orders of magnitude and drives a cylindrical shock wave on a nanometer scale. This wave eventually weakens as the front expands further; but before that, it may contribute to DNA damage due to large pressure gradients developed within a few nanometers from the ion’s trajectory. This mechanism of DNA damage may be a very important contribution to the direct chemical effects of low-energy electrons and holes.

  11. Stochastic threshold for ion heating with beating electrostatic waves.

    PubMed

    Jorns, B; Choueiri, E Y

    2013-06-14

    The stochastic threshold for the heating of ions in a magnetized plasma with two electrostatic waves is experimentally characterized. Two obliquely propagating electrostatic modes are launched in a magnetized plasma with frequencies that differ by the ion cyclotron frequency. The values of the wave amplitudes where a rapid increase in the local ion temperature occurs is then parametrically investigated. It is found that the two threshold wave amplitudes are linearly related and that this dependence translates to a lower required energy density for the onset of heating when compared to the case of a single electrostatic wave. Agreement also is demonstrated between the experimentally observed threshold for stochastic heating and an analytical prediction [B. Jorns and E. Y. Choueiri, Phys. Rev. E 87, 013107 (2013)] for this threshold.

  12. Ion Bernstein waves in a magnetic reconnection region

    NASA Astrophysics Data System (ADS)

    Narita, Y.; Nakamura, R.; Baumjohann, W.; Glassmeier, K. H.; Motschmann, U.; Comisel, H.

    2015-12-01

    Four-dimensional energy spectra and a diagram for dispersion relations are determined for the first time in a magnetic reconnection region in the magnetotail using the four-point magnetometer data from the Cluster mission on a spatial scale of 200 km, about 0.1 ion inertial lengths. The energy spectra are anisotropic with an extension in the perpendicular direction and axially asymmetric with respect to the mean magnetic field. The dispersion diagram for the waves in the quasi-perpendicular directions in the plasma rest frame is in reasonably good agreement with the ion Bernstein waves particularly at the second harmonic of the proton gyro-frequency. Perpendicular-propagating ion Bernstein waves likely exist in an outflow region of magnetic reconnection. We discuss the causality of the Bernstein waves with magnetic reconnection with an estimate of the anomalous resistivity, and propose an observationally-driven model of turbulent magnetic reconnection.

  13. Sounding-Rocket Studies of Langmuir-Wave Microphysics in the Auroral Ionosphere

    NASA Astrophysics Data System (ADS)

    Dombrowski, Micah P.

    Since their discovery in laboratory plasmas in the 1920s, Langmuir waves have been observed to be ubiquitous in plasma environments, particularly in space plasmas. From the greater solar wind to planetary foreshocks and the auroral ionosphere, Langmuir waves are a key factor mediating electron temperature, and controlling electron beam propagation and beam-plasma energy transfer. Because they are so important, Langmuir waves in the space environment have been intensively investigated; however, there remain two challenging types of experiments that are relatively lacking: three-dimensional measurements of Langmuir-wave fields, and measurements of Langmuir wave-electron correlations. This thesis works on filling these two gaps, plus development of new Langmuir-wave instrumentation. The CHARM-II wave-particle Correlator instrument was designed to study the energy transfer between electron beams and plasmas via the sorting of incoming particles by concurrent Langmuir-wave phase, allowing for direct observation of electron bunching. Data from the CHARM-II sounding rocket comprises the first such observations with statistical levels of events, revealing an association between the polarity of the resistive component of the electron phase-bunching and changes in the electron flux at the associated energy, such that a negative resistive component goes with an increase in electron flux, and vice versa, effectively showing energy flow from the beam to the waves, and subsequent enhancements of wave damping. Surprisingly, the results also show comparable amounts of resistive and reactive activity. A test-particle simulation was developed to confirm the details of the theoretical explanation for the observed effect. A three-dimensional Langmuir-wave receiver flown on the TRICE sounding rocket mission reveals the beat signature of the amplitude-modulated 'bursty' form of Langmuir waves which has been observed in many environments. An analysis of the three-dimensional data shows

  14. Self-Consistent Model of Magnetospheric Ring Current and Propagating Electromagnetic Ion Cyclotron Waves: Waves in Multi-Ion Magnetosphere

    NASA Technical Reports Server (NTRS)

    Khazanov, G. V.; Gamayunov, K. V.; Gallagher, D. L.; Kozyra, J. U.

    2006-01-01

    The further development of a self-consistent theoretical model of interacting ring current ions and electromagnetic ion cyclotron waves (Khazanov et al., 2003) is presented In order to adequately take into account wave propagation and refraction in a multi-ion magnetosphere, we explicitly include the ray tracing equations in our previous self-consistent model and use the general form of the wave kinetic equation. This is a major new feature of the present model and, to the best of our knowledge, the ray tracing equations for the first time are explicitly employed on a global magnetospheric scale in order to self-consistently simulate the spatial, temporal, and spectral evolution of the ring current and of electromagnetic ion cyclotron waves To demonstrate the effects of EMIC wave propagation and refraction on the wave energy distribution and evolution, we simulate the May 1998 storm. The main findings of our simulation can be summarized as follows. First, owing to the density gradient at the plasmapause, the net wave refraction is suppressed, and He+-mode grows preferably at the plasmapause. This result is in total agreement with previous ray tracing studies and is very clearly found in presented B field spectrograms. Second, comparison of global wave distributions with the results from another ring current model (Kozyra et al., 1997) reveals that this new model provides more intense and more highly plasmapause-organized wave distributions during the May 1998 storm period Finally, it is found that He(+)-mode energy distributions are not Gaussian distributions and most important that wave energy can occupy not only the region of generation, i.e., the region of small wave normal angles, but all wave normal angles, including those to near 90 . The latter is extremely crucial for energy transfer to thermal plasmaspheric electrons by resonant Landau damping and subsequent downward heat transport and excitation of stable auroral red arcs.

  15. Development of a hybrid wave based-transfer matrix model for sound transmission analysis.

    PubMed

    Dijckmans, A; Vermeir, G

    2013-04-01

    In this paper, a hybrid wave based-transfer matrix model is presented that allows for the investigation of the sound transmission through finite multilayered structures placed between two reverberant rooms. The multilayered structure may consist of an arbitrary configuration of fluid, elastic, or poro-elastic layers. The field variables (structural displacements and sound pressures) are expanded in terms of structural and acoustic wave functions. The boundary and continuity conditions in the rooms determine the participation factors in the pressure expansions. The displacement of the multilayered structure is determined by the mechanical impedance matrix, which gives a relation between the pressures and transverse displacements at both sides of the structure. The elements of this matrix are calculated with the transfer matrix method. First, the hybrid model is numerically validated. Next a comparison is made with sound transmission loss measurements of a hollow brick wall and a sandwich panel. Finally, numerical simulations show the influence of structural damping, room dimensions and plate dimensions on the sound transmission loss of multilayered structures.

  16. Sound radiation from an infinite elastic cylinder with dual-wave propagation-intensity distributions

    NASA Technical Reports Server (NTRS)

    Fuller, C. R.

    1988-01-01

    The radiation of sound from an elastic cylindrical shell filled with fluid and supporting multiwave propagation is studied analytically. Combinations of supersonic and subsonic shell waves are considered. The radiated field is mapped by using acoustic intensity vectors evaluated at various locations. Both time averaged and instantaneous intensity are investigated. The acoustic intensity is seen to vary markedly with axial distance down the cylinder. The effect is shown to be associated with cross terms in the intensity relations, and its magnitude and location to depend upon the relative phase and amplitudes of individual waves. Subsonic shell waves are demonstrated to interact strongly with supersonic shell waves to cause a large modification in the radiated intensity distributions near the shell surface.

  17. Heterodyne mixing of millimetre electromagnetic waves and sub-THz sound in a semiconductor device.

    PubMed

    Heywood, Sarah L; Glavin, Boris A; Beardsley, Ryan P; Akimov, Andrey V; Carr, Michael W; Norman, James; Norton, Philip C; Prime, Brian; Priestley, Nigel; Kent, Anthony J

    2016-08-01

    We demonstrate heterodyne mixing of a 94 GHz millimetre wave photonic signal, supplied by a Gunn diode oscillator, with coherent acoustic waves of frequency ~100 GHz, generated by pulsed laser excitation of a semiconductor surface. The mixing takes place in a millimetre wave Schottky diode, and the intermediate frequency electrical signal is in the 1-12 GHz range. The mixing process preserves all the spectral content in the acoustic signal that falls within the intermediate frequency bandwidth. Therefore this technique may find application in high-frequency acoustic spectroscopy measurements, exploiting the nanometre wavelength of sub-THz sound. The result also points the way to exploiting acoustoelectric effects in photonic devices working at sub-THz and THz frequencies, which could provide functionalities at these frequencies, e.g. acoustic wave filtering, that are currently in widespread use at lower (GHz) frequencies.

  18. Heterodyne mixing of millimetre electromagnetic waves and sub-THz sound in a semiconductor device

    PubMed Central

    Heywood, Sarah L.; Glavin, Boris A.; Beardsley, Ryan P.; Akimov, Andrey V.; Carr, Michael W.; Norman, James; Norton, Philip C.; Prime, Brian; Priestley, Nigel; Kent, Anthony J.

    2016-01-01

    We demonstrate heterodyne mixing of a 94 GHz millimetre wave photonic signal, supplied by a Gunn diode oscillator, with coherent acoustic waves of frequency ~100 GHz, generated by pulsed laser excitation of a semiconductor surface. The mixing takes place in a millimetre wave Schottky diode, and the intermediate frequency electrical signal is in the 1–12 GHz range. The mixing process preserves all the spectral content in the acoustic signal that falls within the intermediate frequency bandwidth. Therefore this technique may find application in high-frequency acoustic spectroscopy measurements, exploiting the nanometre wavelength of sub-THz sound. The result also points the way to exploiting acoustoelectric effects in photonic devices working at sub-THz and THz frequencies, which could provide functionalities at these frequencies, e.g. acoustic wave filtering, that are currently in widespread use at lower (GHz) frequencies. PMID:27477841

  19. Heterodyne mixing of millimetre electromagnetic waves and sub-THz sound in a semiconductor device

    NASA Astrophysics Data System (ADS)

    Heywood, Sarah L.; Glavin, Boris A.; Beardsley, Ryan P.; Akimov, Andrey V.; Carr, Michael W.; Norman, James; Norton, Philip C.; Prime, Brian; Priestley, Nigel; Kent, Anthony J.

    2016-08-01

    We demonstrate heterodyne mixing of a 94 GHz millimetre wave photonic signal, supplied by a Gunn diode oscillator, with coherent acoustic waves of frequency ~100 GHz, generated by pulsed laser excitation of a semiconductor surface. The mixing takes place in a millimetre wave Schottky diode, and the intermediate frequency electrical signal is in the 1–12 GHz range. The mixing process preserves all the spectral content in the acoustic signal that falls within the intermediate frequency bandwidth. Therefore this technique may find application in high-frequency acoustic spectroscopy measurements, exploiting the nanometre wavelength of sub-THz sound. The result also points the way to exploiting acoustoelectric effects in photonic devices working at sub-THz and THz frequencies, which could provide functionalities at these frequencies, e.g. acoustic wave filtering, that are currently in widespread use at lower (GHz) frequencies.

  20. Underwater Sound Levels at a Wave Energy Device Testing Facility in Falmouth Bay, UK.

    PubMed

    Garrett, Joanne K; Witt, Matthew J; Johanning, Lars

    2016-01-01

    Passive acoustic monitoring devices were deployed at FaBTest in Falmouth Bay, UK, a marine renewable energy device testing facility during trials of a wave energy device. The area supports considerable commercial shipping and recreational boating along with diverse marine fauna. Noise monitoring occurred during (1) a baseline period, (2) installation activity, (3) the device in situ with inactive power status, and (4) the device in situ with active power status. This paper discusses the preliminary findings of the sound recording at FabTest during these different activity periods of a wave energy device trial.

  1. Stability of giant sand waves in eastern Long Island Sound, U.S.A.

    USGS Publications Warehouse

    Fenster, M.S.; FitzGerald, D.M.; Bohlen, W.F.; Lewis, R.S.; Baldwin, C.T.

    1990-01-01

    A combination of a highly accurate bathymetric surveying technique and in-situ submersible observations and measurements were used to assess the migrational trends and morphological changes of large sand waves (Ht ??? 17 m) in eastern Long Island Sound. Although residing in a high-energy tidal environment characterized by a net westward sediment flux, the large bedforms are relatively stable over the short term. Over a 7 month period, 55.1% of a total 2942 m of sand wave crestline lengths migrated less than the horizontal accuracy limits of navigation (2 m). Approximately 35% of the remaining sand wave crests migrated less than 4 m. Net migration of the sand wave crests in the study area was 0.2 m. In addition, the bulk form (center of area in profile view) or the base of the sand waves showed little, if any, movement. These data, in conjunction with flow data within the sand wave field, suggest that net migration rates are greater than the time span of this study and/or the sand waves move in response to large residual flows created by high-energy, aperiodic storm events. The latter scenerio suggests that day to day processes only serve to rework and modify the sand waves. ?? 1990.

  2. Ring Current-Electromagnetic Ion Cyclotron Waves Coupling

    NASA Technical Reports Server (NTRS)

    Khazanov, G. V.

    2005-01-01

    The effect of Electromagnetic Ion Cyclotron (EMIC) waves, generated by ion temperature anisotropy in Earth s ring current (RC), is the best known example of wave- particle interaction in the magnetosphere. Also, there is much controversy over the importance of EMIC waves on RC depletion. Under certain conditions, relativistic electrons, with energies 21 MeV, can be removed from the outer radiation belt (RB) by EMIC wave scattering during a magnetic storm. That is why the calculation of EMIC waves must be a very critical part of the space weather studies. The new RC model that we have developed and present for the first time has several new features that we have combine together in a one single model: (a) several lower frequency cold plasma wave modes are taken into account; (b) wave tracing of these wave has been incorporated in the energy EMIC wave equation; (c) no assumptions regarding wave shape spectra have been made; (d) no assumptions regarding the shape of particle distribution have been made to calculate the growth rate; (e) pitch-angle, energy, and mix diffusions are taken into account together for the first time; (f) the exact loss-cone RC analytical solution has been found and coupled with bounce-averaged numerical solution of kinetic equation; (g) the EMIC waves saturation due to their modulation instability and LHW generation are included as an additional factor that contributes to this process; and (h) the hot ions were included in the real part of dielectric permittivity tensor. We compare our theoretical results with the different EMIC waves models as well as RC experimental data.

  3. A Reconfigurable Sound Wave Decomposition Filterbank for Hearing Aids Based on Nonlinear Transformation.

    PubMed

    Huang, Shaoguang; Tian, Lan; Ma, Xiaojie; Wei, Ying

    2016-04-01

    Hearing impaired people have their own hearing loss characteristics and listening preferences. Therefore hearing aid system should become more natural, humanized and personalized, which requires the filterbank in hearing aids provides flexible sound wave decomposition schemes, so that patients are likely to use the most suitable scheme for their own hearing compensation strategy. In this paper, a reconfigurable sound wave decomposition filterbank is proposed. The prototype filter is first cosine modulated to generate uniform subbands. Then by non-linear transformation the uniform subbands are mapped to nonuniform subbands. By changing the control parameters, the nonlinear transformation changes which leads to different subbands allocations. It provides four different sound wave decomposition schemes without changing the structure of the filterbank. The performance of the proposed reconfigurable filterbank was compared with that of fixed filerbanks, fully customizable filterbanks and other existing reconfigurable filterbanks. It is shown that the proposed filterbank provides satisfactory matching performance as well as low complexity and delay, which make it suitable for real hearing aid applications.

  4. A Discrete Constraint for Entropy Conservation and Sound Waves in Cloud-Resolving Modeling

    NASA Technical Reports Server (NTRS)

    Zeng, Xi-Ping; Tao, Wei-Kuo; Simpson, Joanne

    2003-01-01

    Ideal cloud-resolving models contain little-accumulative errors. When their domain is so large that synoptic large-scale circulations are accommodated, they can be used for the simulation of the interaction between convective clouds and the large-scale circulations. This paper sets up a framework for the models, using moist entropy as a prognostic variable and employing conservative numerical schemes. The models possess no accumulative errors of thermodynamic variables when they comply with a discrete constraint on entropy conservation and sound waves. Alternatively speaking, the discrete constraint is related to the correct representation of the large-scale convergence and advection of moist entropy. Since air density is involved in entropy conservation and sound waves, the challenge is how to compute sound waves efficiently under the constraint. To address the challenge, a compensation method is introduced on the basis of a reference isothermal atmosphere whose governing equations are solved analytically. Stability analysis and numerical experiments show that the method allows the models to integrate efficiently with a large time step.

  5. Electrostatic Wave Generation and Transverse Ion Acceleration by Alfvenic Wave Components of BBELF Turbulence

    NASA Technical Reports Server (NTRS)

    Singh, Nagendra; Khazanov, George; Mukhter, Ali

    2007-01-01

    We present results here from 2.5-D particle-in-cell simulations showing that the electrostatic (ES) components of broadband extremely low frequency (BBELF) waves could possibly be generated by cross-field plasma instabilities driven by the relative drifts between the heavy and light ion species in the electromagnetic (EM) Alfvenic component of the BBELF waves in a multi-ion plasma. The ES components consist of ion cyclotron as well as lower hybrid modes. We also demonstrate that the ES wave generation is directly involved in the transverse acceleration of ions (TAI) as commonly measured with the BBELF wave events. The heating is affected by ion cyclotron resonance in the cyclotron modes and Landau resonance in the lower hybrid waves. In the simulation we drive the plasma by the transverse electric field, E(sub y), of the EM waves; the frequency of E(sub y), omega(sub d), is varied from a frequency below the heavy ion cyclotron frequency, OMEGA(sub h), to below the light ion cyclotron frequency, OMEGA(sub i). We have also performed simulations for E(sub y) having a continuous spectrum given by a power law, namely, |Ey| approx. omega(sub d) (exp -alpha), where the exponent alpha = _, 1, and 2 in three different simulations. The driving electric field generates polarization and ExB drifts of the ions and electrons. When the interspecies relative drifts are sufficiently large, they drive electrostatic waves, which cause perpendicular heating of both light and heavy ions. The transverse ion heating found here is discussed in relation to observations from Cluster, FAST and Freja.

  6. Are Ring Current Ions Lost in Electromagnetic Ion Cyclotron Wave Dispersion Relation?

    NASA Technical Reports Server (NTRS)

    Khazanov, G. V.; Gamayunov, K. V.

    2006-01-01

    Electromagnetic ion cyclotron (EMIC) waves are widely observed in the inner and outer magnetosphere, at geostationary orbit, at high latitudes along the plasmapause, and at the ionospheric altitudes. Interaction of the Ring Current (RC) ions and EMIC waves causes ion scattering into the loss cone and leads to decay of the RC, especially during the main phase of storms when the RC decay times of about one hour or less are observed. The oblique EMIC waves damp due to Landau resonance with the thermal plasmaspheric electrons, and subsequent transport of the dissipating wave energy into the ionosphere below causes an ionosphere temperature enhancement. Induced scattering of these waves by the plasmaspheric thermal ions leads to ion temperature enhancement, and forms a so-called hot zone near the plasmapause where the temperature of core plasma ions can reach tens of thousands of degrees. Relativistic electrons in the outer radiation belt also interact well with the EMIC waves, and during the main and/or recovery phases of the storms these electrons can easily be scattered into the loss cone over a time scale from several hours to a day. The plasma density distribution in the magnetosphere and the ion content play a critical role in EMIC wave generation and propagation, but the wave dispersion relation in the known RC-EMIC wave interaction models is assumed to be determined by the thermal plasma distribution only. In these models, the modification of the EMIC wave dispersion relation caused by the RC ions is not taken into account, and the RC ions are only treated as a source of free energy in order to generate EMIC waves. At the same time, the RC ions can dominate the thermal magnetospheric content in the night MLT sector at great L shells during the main and/or recovery storm phase. In this study, using our self-consistent RC-EMIC wave model [Khazanov et al., 2006], we simulate the May 1998 storm in order to quantify the global EMIC wave redistribution caused by

  7. Effect of Ring Current Ions on Electromagnetic Ion Cyclotron Wave Dispersion Relation

    NASA Technical Reports Server (NTRS)

    Gamayunov, K. V.; Khazanov, G. V.

    2006-01-01

    Electromagnetic ion cyclotron (EMIC) waves are widely observed in the inner and outer magnetosphere, at geostationary orbit, at high latitudes along the plasmapause, and at the ionospheric altitudes. Interaction of the Ring Current (RC) ions and EMIC waves causes ion scattering into the loss cone and leads to decay of the RC, especially during the main phase of storms when the RC decay times of about one hour or less are observed. The oblique EMIC waves damp due to Landau resonance with the thermal plasmaspheric electrons, and subsequent transport of the dissipating wave energy into the ionosphere below causes an ionosphere temperature enhancement. Induced scattering of these waves by the plasmaspheric thermal ions leads to ion temperature enhancement, and forms a so-called hot zone near the plasmapause where the temperature of core plasma ions can reach tens of thousands of degrees. Relativistic electrons in the outer radiation belt also interact well with the EMIC waves, and during the main and/or recovery phases of the storms these electrons can easily be scattered into the loss cone over a time scale from several hours to a day. The plasma density distribution in the magnetosphere and the ion content play a critical role in EMIC wave generation and propagation, but the wave dispersion relation in the known RC-EMIC wave interaction models is assumed to be determined by the thermal plasma distribution only. In these models, the modification of the EMIC wave dispersion relation caused by the RC ions is not taken into account, and the RC ions are only treated as a source of free energy in order to generate EMIC waves. At the same time, the RC ions can dominate the thermal magnetospheric content in the night MLT sector at great L shells during the main and/or recovery storm phase. In this study, using our self-consistent RC-EMIC wave model [Khazanov et al., 2006], we simulate the May 1998 storm in order to quantify the global EMIC wave redistribution caused by

  8. Self-Consistent Model of Magnetospheric Ring Current and Propagating Electromagnetic Ion Cyclotron Waves. 1; Waves in Multi Ion Magnetosphere

    NASA Technical Reports Server (NTRS)

    Khazanov, G. V.; Gumayunov, K. V.; Gallagher, D. L.; Kozyra, J. U.

    2006-01-01

    The further development of a self-consistent theoretical model of interacting ring current ions and electromagnetic ion cyclotron waves [Khazanov et al., 2003] is presented. In order to adequately take into account the wave propagation and refraction in a multi-ion plasmasphere, we explicitly include the ray tracing equations in our previous self-consistent model and use the general form of the wave kinetic equation. This is a major new feature of the present model and, to the best of our knowledge, the ray tracing equations for the first time are explicitly employed on a global magnetospheric scale in order to self-consistently simulate spatial, temporal, and spectral evolutions of the ring current and electromagnetic ion cyclotron waves. To demonstrate the effects of EMIC wave propagation and refraction on the EMIC wave energy distributions and evolution we simulate the May 1998 storm. The main findings of our simulation can be summarized as follows. First, due to the density gradient at the plasmapause, the net wave refraction is suppressed, and He(+)-mode grows preferably at plasmapause. This result is in a total agreement with the previous ray tracing studies, and very clear observed in presented B-field spectrograms. Second, comparison the global wave distributions with the results from other ring current model [Kozyra et al., 1997] reveals that our model provides more intense and higher plasmapause organized distributions during the May, 1998 storm period. Finally, the found He(+)-mode energy distributions are not Gaussian distributions, and most important that wave energy can occupy not only the region of generation, i. e. the region of small wave normal angles, but the entire wave normal angle region and even only the region near 90 degrees. The latter is extremely crucial for energy transfer to thermal plasmaspheric electrons by resonant Landau damping, and subsequent downward heat transport and excitation of stable auroral red arcs.

  9. Nonlinear heating of ions by electron cyclotron frequency waves

    NASA Astrophysics Data System (ADS)

    Zestanakis, P. A.; Hizanidis, K.; Ram, A. K.; Kominis, Y.

    2010-11-01

    We study the nonlinear interaction of ions with electron cyclotron (EC) wave packets in a magnetized plasma. Previous studies have shown that such interactions with high frequency electrostatic lower hybrid waves can lead to coherent energization of ions. It requires the frequency bandwidth of the wave packet to be broader than the ion cyclotron frequency [1,2]. For the electromagnetic high frequency EC waves we have developed a more general theory, based on the Lie transform canonical perturbation method [3,4]. We apply the theory to the case of two overlapping EC beams. The wave frequency of each beam is assumed to be frequency modulated with a modulation bandwidth comparable to the ion cyclotron frequency. We present results for both X-mode and O-mode and illustrate the conditions for ion energization. [4pt] [1] D. Benisti, A. K. Ram, and A. Bers, Phys. Plasmas 5, 3224 (1998). [0pt] [2] A. K. Ram, A. Bers, and D. Benisti , J. Geophys. Res. 103, 9431 (1998). [0pt] [3] J.R. Cary and A.N. Kaufman, Phys. Fluids 24, 1238 (1981). [0pt] [4] R.L. Dewar, J. Phys A-Math. Gen 9, 2043 (1976).

  10. Excitation of low frequency waves by streaming ions via anomalous cyclotron resonance

    NASA Technical Reports Server (NTRS)

    Wu, C. S.; Dillenburg, D.; Gaffey, J. D., Jr.; Ziebell, L. F.; Goedert, J.; Freund, H. P.

    1978-01-01

    The effect of a small population of streaming ions on low-frequency waves with frequencies below the ion cyclotron frequency is analyzed for three modes of interest: Alfven waves, magnetosonic waves, and ion-cyclotron waves. The instability mechanism is the anomalous cyclotron resonance of the waves with the streaming ions. Conditions for excitation of the three types of waves are derived and expressions for the growth rates are obtained. Excitation of Alfven waves is possible even if the ratio of the densities of the streaming ions to the thermal ions is very small. For magnetosonic waves, excitation can easily occur if waves are propagating parallel or nearly parallel to the ambient magnetic field. As for ion-cyclotron waves, it is found that for the ion-whistler branch the excitation is suppressed over a broader range of wave frequencies than for the fast magnetosonic branch.

  11. Alfven waves and associated energetic ions downstream from Uranus

    SciTech Connect

    Zhang, Ming; Belcher, J.W.; Richardson, J.D. ); Smith, C.W. )

    1991-02-01

    The authors report the observation of low-frequency waves in the solar wind downstream from Uranus. These waves are observed by the Voyager spacecraft for more than 2 weeks after the encounter with Uranus and are present during this period whenever the interplanetary magnetic field is oriented such that the field lines intersect the Uranian bow shock. The magnetic field and velocity components transverse to the background field are strongly correlated, consistent with the interpretation that these waves are Alfvenic and/or fast-mode waves. The waves have a spacecraft frame frequency of about 10{sup {minus}3} Hz, and when first observed near the bow shock have an amplitude comparable to the background field. As the spacecraft moves farther from Uranus, the amplitude decays. The waves appear to propagate along the magnetic field lines outward from Uranus and are right-hand polarized. Theory suggests that these waves are generated in the upstream region by a resonant instability with a proton beam streaming along the magnetic field lines. The solar wind subsequently carries these waves downstream to the spacecraft location. These waves are associated with the presence of energetic (> 28 keV) ions observed by the low-energy charged particle instrument. These ions appear two days after the start of the wave activity and occur thereafter whenever the Alfven waves occur, increasing in intensity away from Uranus. The ions are argued to originate in the Uranian magnetosphere, but pitch-angle scattering in the upstream region is required to bring them downstream to the spacecraft location.

  12. High-Frequency Electrostatic Wave Generation and Transverse Ion Acceleration by Low Alfvenic Wave Components of BBELF Turbulence

    NASA Technical Reports Server (NTRS)

    Singh, Nagendra; Khazanov, George; Mukhter, Ali

    2006-01-01

    Satellite observations in the auroral plasma have revealed that extremely low frequency (ELF) waves play a dominant role in the acceleration of electrons and ions in the auroral plasma. The electromagnetic components of the ELF (EMELF) waves are the electromagnetic ion cyclotron (EMIC) waves below the cyclotron frequency of the lightest ion species in a multi-ion plasma. Shear Alfv6n waves (SAWS) constitute the lowest frequency components of the ELF waves below the ion cyclotron frequency of the heaviest ion. The -2 mechanism for the transfer of energy from such EMELF waves to ions affecting transverse ion heating still remains a matter of debate. A very ubiquitous fe8ture of ELF waves now observed in several rocket and satellite experiments is that they occur in conjunction with high-frequency electrostatic waves. The frequency spectrum of the composite wave turbulence extends from the low frequency of the Alfvenic waves to the high frequency of proton plasma frequency and/or the lower hybrid frequency. The spectrum does not show any feature organized by the ion cyclotron frequencies and their harmonics. Such broadband waves consisting of both the EM and ES waves are now popularly referred as BBELF waves. We present results here from 2.5-D particle-in-cell simulations showing that the ES components are directly generated by cross- field plasma instabilities driven by the drifts of the ions and electrons in the EM component of the BBELF waves.

  13. Ion acoustic solitary waves in plasmas with nonextensive electrons, Boltzmann positrons and relativistic thermal ions

    NASA Astrophysics Data System (ADS)

    Hafez, M. G.; Talukder, M. R.

    2015-09-01

    This work investigates the theoretical and numerical studies on nonlinear propagation of ion acoustic solitary waves (IASWs) in an unmagnetized plasma consisting of nonextensive electrons, Boltzmann positrons and relativistic thermal ions. The Korteweg-de Vries (KdV) equation is derived by using the well known reductive perturbation method. This equation admits the soliton like solitary wave solution. The effects of phase velocity, amplitude of soliton, width of soliton and electrostatic nonlinear propagation of weakly relativistic ion-acoustic solitary waves have been discussed with graphical representation found in the variation of the plasma parameters. The obtained results can be helpful in understanding the features of small but finite amplitude localized relativistic ion-acoustic waves for an unmagnetized three component plasma system in astrophysical compact objects.

  14. Excitation of Ion Acoustic Waves by Electron Beams

    NASA Astrophysics Data System (ADS)

    Sydorenko, Dmytro; Tokluoglu, Erinc; Kaganovich, Igor; Startsev, Edward; Davidson, Ronald

    2012-10-01

    The interaction of electron beams with plasmas is of considerable importance particularly for hybrid DC/RF coupled plasma sources used in plasma processing [1]. An electron beam is formed by emission from one surface, is accelerated through a dc bias electric field and enters the bulk plasma. Emitted electrons excite electron plasma (Langmuir) waves through the two-stream instability. Due to the high localized plasmon pressure, ion acoustic waves are excited parametrically. The plasma waves saturate by non-linear wave trapping. Eventually coupling between electron plasma waves and ion acoustic waves deteriorates the Langmuir waves, which leads to a bursting behavior. The two-stream instability and the consequent ion fluctuations are studied over a wide range of system parameters using the particle-in-cell codes EDIPIC and LSP. The influenceof these instabilities on collisionless electron heating are presented for a hybrid RF-DC plasma source.[4pt] [1] Lin Xu, et al, Appl. Phys. Lett., 93, 261502 (2008).

  15. Acoustic waves generated from seismic surface waves: propagation properties determined from Doppler sounding observations and normal-mode modelling

    NASA Astrophysics Data System (ADS)

    Artru, Juliette; Farges, Thomas; Lognonné, Philippe

    2004-09-01

    Since 1960, experiments have shown that perturbations of the ionosphere can occur after earthquakes, by way of dynamic coupling between seismic surface waves and the atmosphere. The atmospheric wave is amplified exponentially while propagating upwards due to the decrease of density, and interaction with the ionospheric plasma leads to clearly identified signals on both ground-based or satellite ionospheric measurements. In 1999 and 2000, after an upgrade of the HF Doppler sounder, the Commisariat à l'Énergie Atomique systematically recorded these effects in the ionosphere with the Francourville (France) network, by measuring vertical oscillations of ionospheric layers with the Doppler technique. Normal-mode theory extended to a solid Earth with an atmosphere allows successful modelling of such signals, even if this 1-D approach is probably too crude, especially in the solid Earth, where 20 s surface waves see large lateral variations in the crust. The combination of observations and simulations provides a new tool to determine acoustic gravity wave propagation characteristics from the ground to ionospheric height. Observed velocity and amplification of the atmospheric waves show good agreement from the ground up to moderate sounding altitudes (140-150 km); however, at higher altitudes the propagation speed is found to be much smaller than predicted and attenuation is underestimated. This shows that the standard formalism of acoustic gravity waves in the atmosphere cannot efficiently describe propagation in the ionized atmosphere. Further work is needed to characterize the propagation of acoustic waves in this altitude range: we believe that seismic waves can provide a well-constrained source for such study.

  16. Collapse of a nanoscopic void triggered by a spherically symmetric traveling sound wave.

    PubMed

    Hołyst, Robert; Litniewski, Marek; Garstecki, Piotr

    2012-05-01

    Molecular-dynamics simulations of the Lennard-Jones fluid (up to 10(7) atoms) are used to analyze the collapse of a nanoscopic bubble. The collapse is triggered by a traveling sound wave that forms a shock wave at the interface. The peak temperature T(max) in the focal point of the collapse is approximately ΣR(0)(a), where Σ is the surface density of energy injected at the boundary of the container of radius R(0) and α ≈ 0.4-0.45. For Σ = 1.6 J/m(2) and R(0) = 51 nm, the shock wave velocity, which is proportional to √Σ, reaches 3400 m/s (4 times the speed of sound in the liquid); the pressure at the interface, which is proportional to Σ, reaches 10 GPa; and T(max) reaches 40,000 K. The Rayleigh-Plesset equation together with the time of the collapse can be used to estimate the pressure at the front of the shock wave.

  17. Planar and nonplanar ion acoustic shock waves in relativistic degenerate astrophysical electron-positron-ion plasmas

    SciTech Connect

    Ata-ur-Rahman,; Qamar, A.; Ali, S.; Mirza, Arshad M.

    2013-04-15

    We have studied the propagation of ion acoustic shock waves involving planar and non-planar geometries in an unmagnetized plasma, whose constituents are non-degenerate ultra-cold ions, relativistically degenerate electrons, and positrons. By using the reductive perturbation technique, Korteweg-deVries Burger and modified Korteweg-deVries Burger equations are derived. It is shown that only compressive shock waves can propagate in such a plasma system. The effects of geometry, the ion kinematic viscosity, and the positron concentration are examined on the ion acoustic shock potential and electric field profiles. It is found that the properties of ion acoustic shock waves in a non-planar geometry significantly differ from those in planar geometry. The present study has relevance to the dense plasmas, produced in laboratory (e.g., super-intense laser-dense matter experiments) and in dense astrophysical objects.

  18. Solitary and freak waves in superthermal plasma with ion jet

    NASA Astrophysics Data System (ADS)

    Abdelsalam, U. M.; Abdelsalam

    2013-06-01

    The nonlinear solitary and freak waves in a plasma composed of positive and negative ions, superthermal electrons, ion beam, and stationary dust particles have been investigated. The reductive perturbation method is used to obtain the Korteweg-de Vries (KdV) equation describing the system. The latter admits solitary wave solution, while the dynamics of the modulationally unstable wavepackets described by the KdV equation gives rise to the formation of freak/rogue excitation described by the nonlinear Schrödinger equation. In order to show that the characteristics of solitary and freak waves are influenced by plasma parameters, relevant numerical analysis of appropriate nonlinear solutions are presented. The results from this work predict nonlinear excitations that may associate with ion jet and superthermal electrons in Herbig-Haro objects.

  19. LH wave absorption by mode conversion near ion cyclotron harmonics

    SciTech Connect

    Ko, K.; Bers, A.; Fuchs, V.

    1981-02-01

    Numerical studies of the dispersion relation near the lower-hybrid frequency in an inhomogeneous plasma (..delta.. n, ..delta.. T, ..delta.. B) show that portions of an incident lower-hybrid wave spectrum undergo successive but partial mode conversions to warm-plasma waves in the presence of ion cyclotron harmonics. Wave absorption beyond the first mode conversion occurs near an ion cyclotron harmonic where ion Landau damping is enhanced. A second-order dispersion relation numerically in good agreement with the full dispersion relation in the mode conversion region is derived using the condition par. delta D/par. delta k = 0. The mode conversion efficiency at each confluence is evaluated by solving the corresponding differential equation.

  20. Flute waves at the ion Larmor radius scales

    SciTech Connect

    Onishchenko, O. G.

    2010-12-14

    The theory of the magnetic Rayleigh-Taylor instability (RTI) is discussed. Modified linear kinetic theory allows us to investigate RTI and flute waves with arbitrary perpendicular spatial scales compared to the ion Larmor radius. It is shown that in the linear limit a Fourier transform of these equations yields the dispersion relation which in the so-called Pade approximation corresponds to results of the kinetic theory. This analysis represents an extension of the previous study of the magnetic RTI obtained in the large wave scale approximation. It is shown that incorporation of the effects associated with wave scales of the order of the ion Larmor radius leads to a broader wave number range of the magnetic RTI.

  1. A model for gravity-wave spectra observed by Doppler sounding systems

    NASA Technical Reports Server (NTRS)

    Vanzandt, T. E.

    1986-01-01

    A model for Mesosphere - Stratosphere - Troposphere (MST) radar spectra is developed following the formalism presented by Pinkel (1981). Expressions for the one-dimensional spectra of radial velocity versus frequency and versus radial wave number are presented. Their dependence on the parameters of the gravity-wave spectrum and on the experimental parameters, radar zenith angle and averaging time are described and the conditions for critical tests of the gravity-wave hypothesis are discussed. The model spectra is compared with spectra observed in the Arctic summer mesosphere by the Poker Flat radar. This model applies to any monostatic Doppler sounding system, including MST radar, Doppler lidar and Doppler sonar in the atmosphere, and Doppler sonar in the ocean.

  2. Ion-acoustic cnoidal waves in plasmas with warm ions and kappa distributed electrons and positrons

    NASA Astrophysics Data System (ADS)

    Kaladze, T.; Mahmood, S.

    2014-03-01

    Electrostatic ion-acoustic periodic (cnoidal) waves and solitons in unmagnetized electron-positron-ion (EPI) plasmas with warm ions and kappa distributed electrons and positrons are investigated. Using the reductive perturbation method, the Korteweg-de Vries (KdV) equation is derived with appropriate boundary conditions for periodic waves. The corresponding analytical and various numerical solutions are presented with Sagdeev potential approach. Differences between the results caused by the kappa and Maxwell distributions are emphasized. It is revealed that only hump (compressive) structures of the cnoidal waves and solitons are formed. It is shown that amplitudes of the cnoidal waves and solitons are reduced in an EPI plasma case in comparison with the ordinary electron-ion plasmas. The effects caused by the temperature variations of the warm ions are also discussed. It is obtained that the amplitude of the cnoidal waves and solitons decreases for a kappa distributed (nonthermal) electrons and positrons plasma case in comparison with the Maxwellian distributed (thermal) electrons and positrons EPI plasmas. The existence of kappa distributed particles leads to decreasing of ion-acoustic frequency up to thermal ions frequency.

  3. Simulations of heavy ion heating by electromagnetic ion cyclotron waves driven by proton temperature anisotropies

    NASA Technical Reports Server (NTRS)

    Tanaka, M.

    1985-01-01

    Heating of heavy ions by the electromagnetic ion cyclotron (EMIC) waves, which are driven by proton temperature anisotropies, is studied by means of hybrid particle simulations. Initially, relaxation of the temperature anisotropies in the proton distribution and isotropic heating of the heavy ions are observed (phase I), followed by substantial perpendicular heating of the heavy ions (phase II). The heavy ions are distinctly gyrophase modulated by the EMIC waves. The isotropic heating in phase I is due to magnetic trapping by the excited proton cyclotron waves. The perpendicular heating in phase II is attributed to cyclotron resonance with the EMIC waves, which becomes possible by means of the preceding heating in phase I. Saturation of the EMIC instability is instead attributed to magnetic trapping of the majority ions: protons. When the proton anisotropy is very large, frequency shift (decrease) of the proton cyclotron waves to less than 1/2 Ohm(p) is observed. The present mechanism is not only relevant to He(+) heating in the dayside equator of the magnetosphere, but it also predicts hot He2(+) ions behind the earth's bow shock.

  4. Shock waves in dusty plasma with two temperature superthermal ions

    NASA Astrophysics Data System (ADS)

    Ghai, Yashika; Saini, N. S.

    2017-03-01

    An investigation of dust acoustic shock waves in dusty plasma containing two temperature ions is presented. The present investigation is motivated by the observations of Geotail spacecraft that report the occurrence of two temperature ion populations in Earth's magnetotail. We have derived Burgers equation to study dust acoustic shock structures in an unmagnetized plasma with two temperature superthermal ions. We have also derived the modified Burgers equation at critical values of physical parameters for which nonlinear coefficient (A) of Burgers equation vanishes. The numerical analysis is performed in context with observations in Earth's magnetotail and the influence of various plasma parameters viz. ions temperature ratio, superthermality of hot and cold ions, kinematic viscosity etc. has been observed on characteristics of DA shocks. It is observed that the amplitude of positive shocks via Burgers equation decreases whereas that of modified shocks with higher order nonlinearity increases with increase in superthermality of cold ions.

  5. Impact of Ring Current Ions on Electromagnetic Ion Cyclotron Wave Dispersion Relation

    NASA Technical Reports Server (NTRS)

    Khazanov, G. V.; Gamayunov, K. V.

    2007-01-01

    Effect of the ring current ions in the real part of electromagnetic ion Cyclotron wave dispersion relation is studied on global scale. Recent Cluster observations by Engebretson et al. showed that although the temperature anisotropy of is energetic (> 10 keV) ring current protons was high during the entire 22 November 2003 perigee pass, electromagnetic ion cyclotron waves were observed only in conjunction with intensification of the ion fluxes below 1 keV by over an order of magnitude. To study the effect of the ring current ions on the wave dispersive properties and the corresponding global wave redistribution, we use a self-consistent model of interacting ring current and electromagnetic ion cyclotron waves, and simulate the May 1998 storm. The main findings of our simulation can be summarized as follows: First, the plasma density enhancement in the night MLT sector during the main and recovery storm phases is mostly caused by injection of suprathermal plasma sheet H + (approximately < 1 keV), which dominate the thermal plasma density. Second, during the recovery storm phases, the ring current modification of the wave dispersion relation leads to a qualitative change of the wave patterns in the postmidnight-dawn sector for L > 4.75. This "new" wave activity is well organized by outward edges of dense suprathermal ring current spots, and the waves are not observed if the ring current ions are not included in the real part of dispersion relation. Third, the most intense wave-induced ring current precipitation is located in the night MLT sector and caused by modification of the wave dispersion relation. The strongest precipitating fluxes of about 8 X 10(exp 6)/ (cm(exp 2) - s X st) are found near L=5.75, MLT=2 during the early recovery phase on 4 May. Finally, the nightside precipitation is more intense than the dayside fluxes, even if there are less intense waves, because the convection field moves ring current ions into the loss cone on the nightside, but drives

  6. Ion-Acoustic Waves in Self-Gravitaing Dusty Plasma

    SciTech Connect

    Kumar, Nagendra; Kumar, Vinod; Kumar, Anil

    2008-09-07

    The propagation and damping of low frequency ion-acoustic waves in steady state, unmagnetised, self-gravitating dusty plasma are studied taking into account two important damping mechanisms creation damping and Tromso damping. It is found that imaginary part of wave number is independent of frequency in case of creation damping. But when we consider the case of creation and Tromso damping together, an additional contribution to damping appears with the increase in frequency attributed to Tromso effect.

  7. Ion-wave stabilization of an inductively coupled plasma

    SciTech Connect

    Camparo, J.C.; Mackay, R.

    2006-04-24

    Stabilization of the rf power driving an inductively coupled plasma (ICP) has implications for fields ranging from atomic clocks to analytical chemistry to illumination technology. Here, we demonstrate a technique in which the plasma itself acts as a probe of radio wave power, and provides a correction signal for active rf-power control. Our technique takes advantage of the resonant nature of forced ion waves in the plasma, and their observation in the ICP's optical emission.

  8. Sound waves in a liquid with polydisperse vapor-gas bubbles

    NASA Astrophysics Data System (ADS)

    Gubaidullin, D. A.; Fedorov, Yu. V.

    2016-03-01

    A mathematical model is presented for the propagation of plane, spherical, and cylindrical sound waves in a liquid containing polydisperse vapor-gas bubbles with allowance for phase transitions. A system of integro-differential equations is constructed to describe perturbed motion of a two-phase mixture, and a dispersion relation is derived. An expression for equilibrium sound velocity is obtained for a gas-liquid or vapor-liquid mixture. The theoretical results agree well with the known experimental data. The dispersion curves obtained for the phase velocity and the attenuation coefficient in a mixture of water with vapor-gas bubbles are compared for various values of vapor concentration in the bubbles and various bubble distributions in size. The evolution of pressure pulses of plane and cylindrical waves is demonstrated for different values of the initial vapor concentration in bubbles. The calculated frequency dependence of the phase sound velocity in a mixture of water with vapor bubbles is compared with experimental data.

  9. Ion Heating by Alfven Waves and Reconnection in NSTX

    NASA Astrophysics Data System (ADS)

    Fredrickson, E. D.

    2006-04-01

    The evolution of laboratory and astrophysical plasmas depends on the flow of energy between the ``equilibrium'' configuration, waves in the plasma and the thermal plasma. We explore two examples of this energy flow. In the first example, data from NSTX is examined for evidence that CAE in the frequency range from ˜ 0.2 fci to ˜ 1.2 fci excited by super-thermal ions might heat the thermal ions. Theory indicates that only a relatively small portion of the beam power would go into exciting the CAE on NSTX, and observations indicate that the amplitude of these waves, deduced from density fluctuations, is below the stochastic threshold for heating. Another example examines how internal magnetic reconnections can lead to heating of the thermal ions. One model postulates the excitation of a high frequency wave, which then damps on the ions. High frequency waves are indeed seen to follow some NSTX reconnection events. The second invokes direct acceleration of the thermal ions by the induced electric field [P. Helander, L.-G. Eriksson, R.J. Akers, et al.,Phys. Rev. Lett. 89 (2002) 235002-1]. In collaboration with S.S. Medley, Princeton Plasma Physics Laboratory.

  10. Estimation of seismic wave velocity at seafloor surface and sound source localization based on transmitted wave observation with an ocean bottom seismometer offshore of Kamaishi, Japan

    NASA Astrophysics Data System (ADS)

    Iwase, Ryoichi

    2016-07-01

    An in situ method of estimating the seismic wave velocity at the seafloor surface by observing the particle motion of a wave transmitted into the sediment is presented; this method uses a sound source whose location is known. Conversely, a sound source localization method using the obtained seismic velocities and involving particle motion observation is also presented. Although this method is applicable only when the sound source exists within the critical incidence angle range, it is expected to contribute to the tracing of vocalizing baleen whales, which are unknown around Japanese waters.

  11. Electrostatic ion-cyclotron waves in a nonuniform magnetic field

    NASA Technical Reports Server (NTRS)

    Cartier, S. L.; Dangelo, N.; Merlino, R. L.

    1985-01-01

    The properties of electrostatic ion-cyclotron waves excited in a single-ended cesium Q machine with a nonuniform magnetic field are described. The electrostatic ion-cyclotron waves are generated in the usual manner by drawing an electron current to a small exciter disk immersed in the plasma column. The parallel and perpendicular (to B) wavelengths and phase velocities are determined by mapping out two-dimensional wave phase contours. The wave frequency f depends on the location of the exciter disk in the nonuniform magnetic field, and propagating waves are only observed in the region where f is approximately greater than fci, where fci is the local ion-cyclotron frequency. The parallel phase velocity is in the direction of the electron drift. From measurements of the plasma properties along the axis, it is inferred that the electron drift velocity is not uniform along the entire current channel. The evidence suggests that the waves begin being excited at that axial position where the critical drift velocity is first exceeded, consistent with a current-driven excitation mechanism.

  12. Ion-acoustic waves in ultracold neutral plasmas: Modulational instability and dissipative rogue waves

    NASA Astrophysics Data System (ADS)

    El-Tantawy, S. A.

    2017-02-01

    Progress is reported on the modulational instability (MI) of ion-acoustic waves (IAWs) and dissipative rogue waves (RWs) in ultracold neutral plasmas (UNPs). The UNPs consist of inertial ions fluid and Maxwellian inertialess hot electrons, and the presence of an ion kinematic viscosity is allowed. For this purpose, a modified nonlinear Schrödinger equation (NLSE) is derived and then solved analytically to show the occurrence of MI. It is found that the (in)stability regions of the wavepacks are dependent on time due to of the existence of the dissipative term. The existing regions of the MI of the IAWs are inventoried precisely. After that, we use a suitable transformation to convert the modified NLSE into the normal NLSE whose analytical solutions for rogue waves are known. The rogue wave propagation condition and its behavior are discussed. The impact of the relevant physical parameters on the profile of the RWs is examined.

  13. Wave-particle resonance condition test for ion-kinetic waves in the solar wind

    NASA Astrophysics Data System (ADS)

    Narita, Y.; Marsch, E.; Perschke, C.; Glassmeier, K.-H.; Motschmann, U.; Comişel, H.

    2016-04-01

    Conditions for the Landau and cyclotron resonances are tested for 543 waves (identified as local peaks in the energy spectra) in the magnetic field fluctuations of the solar wind measured by the Cluster spacecraft on a tetrahedral scale of 100 km. The resonance parameters are evaluated using the frequencies in the plasma rest frame, the parallel components of the wavevectors, the ion cyclotron frequency, and the ion thermal speed. The observed waves show a character of the sideband waves associated with the ion Bernstein mode, and are in a weak agreement with the fundamental electron cyclotron resonance in spite of the ion-kinetic scales. The electron cyclotron resonance is likely taking place in solar wind turbulence near 1 AU (astronomical unit).

  14. Ion temperature in plasmas with intrinsic Alfven waves

    SciTech Connect

    Wu, C. S.; Yoon, P. H.; Wang, C. B.

    2014-10-15

    This Brief Communication clarifies the physics of non-resonant heating of protons by low-frequency Alfvenic turbulence. On the basis of general definition for wave energy density in plasmas, it is shown that the wave magnetic field energy is equivalent to the kinetic energy density of the ions, whose motion is induced by the wave magnetic field, thus providing a self-consistent description of the non-resonant heating by Alfvenic turbulence. Although the study is motivated by the research on the solar corona, the present discussion is only concerned with the plasma physics of the heating process.

  15. Ion temperature in plasmas with intrinsic Alfven waves

    NASA Astrophysics Data System (ADS)

    Wu, C. S.; Yoon, P. H.; Wang, C. B.

    2014-10-01

    This Brief Communication clarifies the physics of non-resonant heating of protons by low-frequency Alfvenic turbulence. On the basis of general definition for wave energy density in plasmas, it is shown that the wave magnetic field energy is equivalent to the kinetic energy density of the ions, whose motion is induced by the wave magnetic field, thus providing a self-consistent description of the non-resonant heating by Alfvenic turbulence. Although the study is motivated by the research on the solar corona, the present discussion is only concerned with the plasma physics of the heating process.

  16. Effects of energetic heavy ions on electromagnetic ion cyclotron wave generation in the plasmapause region

    NASA Technical Reports Server (NTRS)

    Kozyra, J. U.; Cravens, T. E.; Nagy, A. F.; Fontheim, E. G.; Ong, R. S. B.

    1984-01-01

    An expression for electromagnetic ion cyclotron convective growth rates is derived. The derivation of the dispersion relation and convective growth rates in the presence of a multicomponent energetic and cold plasma is presented. The effects that multiple heavy ions in the ring current and cold plasma produce in the growth and propagation characteristics of ion cyclotron waves are explored. Results of growth rate calculations using parameters consistent with conditions in the plasmapause region during the early recovery phase of geomagnetic storms are presented and compared with ground-based and satellite observations of waves in this region. The geophysical implications of the results are discussed.

  17. Ion radial transport induced by ICRF waves in tokamaks

    SciTech Connect

    Chen, L.; Vaclavik, J.; Hammett, G.W.

    1987-05-01

    The wave-induced fluxes of energetic-trapped ions during ICRF heating of tokamak plasmas are calculated using quasilinear equations. A simple single particle model of this transport mechanism is also given. Both a convective flux proportional to k/sub phi/vertical bar E/sub +/vertical bar/sup 2/ and a diffusive flux proportional to k/sub phi//sup 2/vertical bar E/sub +/vertical bar/sup 2/ are found. Here, k/sub phi/ is the toroidal wave number and E/sub +/ is the left-hand polarized wave field. The convective flux may become significant for large k/sub phi/ if the wave spectrum is asymmetric in k/sub phi/. But for the conditions of most previous experiments, these calculations indicate that radial transport driven directly by the ICRF wave is unimportant.

  18. Coupling between ion-acoustic waves and neutrino oscillations.

    PubMed

    Haas, Fernando; Pascoal, Kellen Alves; Mendonça, José Tito

    2017-01-01

    The work investigates the coupling between ion-acoustic waves and neutrino flavor oscillations in a nonrelativistic electron-ion plasma under the influence of a mixed neutrino beam. Neutrino oscillations are mediated by the flavor polarization vector dynamics in a material medium. The linear dispersion relation around homogeneous static equilibria is developed. When resonant with the ion-acoustic mode, the neutrino flavor oscillations can transfer energy to the plasma exciting a new fast unstable mode in extreme astrophysical scenarios. The growth rate and the unstable wavelengths are determined in typical type II supernova parameters. The predictions can be useful for a new indirect probe on neutrino oscillations in nature.

  19. Coupling between ion-acoustic waves and neutrino oscillations

    NASA Astrophysics Data System (ADS)

    Haas, Fernando; Pascoal, Kellen Alves; Mendonça, José Tito

    2017-01-01

    The work investigates the coupling between ion-acoustic waves and neutrino flavor oscillations in a nonrelativistic electron-ion plasma under the influence of a mixed neutrino beam. Neutrino oscillations are mediated by the flavor polarization vector dynamics in a material medium. The linear dispersion relation around homogeneous static equilibria is developed. When resonant with the ion-acoustic mode, the neutrino flavor oscillations can transfer energy to the plasma exciting a new fast unstable mode in extreme astrophysical scenarios. The growth rate and the unstable wavelengths are determined in typical type II supernova parameters. The predictions can be useful for a new indirect probe on neutrino oscillations in nature.

  20. Ion-acoustic solitary waves in ultra-relativistic degenerate pair-ion plasmas

    SciTech Connect

    Rasheed, A.; Tsintsadze, N. L.; Murtaza, G.

    2011-11-15

    The arbitrary and the small amplitude ion-acoustic solitary waves (IASWs) have been studied. The former is studied by using the Sagdeev pseudo-potential approach in a plasma consisting of the degenerate ultrarelativistic electrons, positrons, and the non-relativistic classical ions. It is seen that only compressive solitary waves can propagate through such plasmas. The numerical calculations show that the region of existence of the ion-acoustic solitary waves depends upon the positron (ion) number density and the plasma thermal temperature. This study is appropriate for applications in inertial confinement fusion laboratory research as well as the study of astrophysical dense objects such as white dwarf and dense neutron stars.

  1. Sounding rocket based investigations of HF waves in the auroral ionosphere

    NASA Astrophysics Data System (ADS)

    McAdams, Kristin Lynn

    1999-10-01

    The PHAZE II and Auroral Turbulence II sounding rockets were launched into active, pre-midnight aurora during the February 1997 sounding rocket campaign from Poker Flat, Alaska. Both rockets carried a full complement of plasma intruments including particle detectors and electric field instruments. The high frequency electric field instrument (HFE), flown on both rockets, was designed and built at Dartmouth College. This unusual instrument transmitted the full electric field waveform using a dedicated telemetry link. The unprecedented resolution in both frequency and time yielded the first identifiable observations of several HF wave phenomena. We investigated two of these phenomena, HF chirps in the region when fpe > fce and HF bands at higher altitudes where fpe < fce. HF chirps are extremely narrowband, short-lived emissions which occur when fpe > fce. We propose that these waves are created as Z-modes waves which are quasi- trapped in density cavities. HF bands have long durations and narrowband, constant frequency structure and are observed in regions where the local plasma density is varying. These emissions occur when fpe < fce and the whistler mode connects to the Langmuir mode. They are generated by an electron beam interaction which produces Langmuir waves which then move onto the whistler mode when the local plasma density increases. The HFE also provided a method for determining the local plasma density without relying on Langmuir probes or active plasma experiments. When the frequency cutoff of the background wideband emissions is evident, this cutoff is used as a track of the local plasma frequency, which is dependent on the plasma density. We used this technique to definitively correlate lower hybrid solitary structures with density gradients. The use of the HFE on both flights has allowed us to observe HF wave phenomena which have been inaccessible previously.

  2. Analysis of EMIC waves in relation to magnetospheric heavy ion density

    NASA Astrophysics Data System (ADS)

    Kim, H.; Kim, E. H.; Johnson, J.; Lee, D. H.; Clauer, C. R.; Lessard, M.; Engebretson, M. J.; Xu, Z.

    2014-12-01

    This study presents observations of EMIC wave events and their relation to heavy ion density in the magnetosphere. It is well known that EMIC waves play an important role in particle acceleration and loss via wave-particle interaction. It is critical to know the ion composition in the plasma with which EMIC waves interact in order to understand wave generation and propagation because it controls ion cyclotron resonance frequencies of EMIC waves. The presence of heavy ions (He+ and O+) causes the wave modes to be more complex with two additional resonance (ion-ion hybrid and Buchsbaum resonances) and polarization changes, making it challenging to analyze wave generation and propagation. In this study, we show wave polarization and Poynting flux using data from the Time History of Events and Macroscale Interactions during Substorms (THEMIS) and Van Allen Probes (VAP) satellites and their ground conjunctions and compare them with the heavy ion density estimated by a wave model.

  3. Simulating Negative Pickup Ions and Ion Cyclotron Wave Generation at Europa (Invited)

    NASA Astrophysics Data System (ADS)

    Desai, R. T.; Cowee, M.; Gary, S. P.; Wei, H.; Coates, A. J.; Kataria, D. O.; Fu, X.

    2015-12-01

    The mass loading of space environments through the ionisation of planetary atmospheres is a fundamental process governing the plasma interactions and long term evolution of celestial bodies across the solar system. Regions containing significant pickup ion populations have been observed to exhibit a rich variety of electromagnetic plasma wave phenomena, the characteristics and properties of which can be used to infer the ion species present, their spatial and temporal distributions, and the global ionisation rates of the neutral material. In this study we present hybrid (kinetic ion, massless fluid electron) simulations of ion pickup and Ion Cyclotron (IC) waves observed in the Jovian magnetosphere and draw comparisons to sub-alfvénic pickup observed by Cassini in the Saturnian system, and also to supra-alfvénic pickup at planetary bodies immersed directly in the solar wind. At Jupiter, Europa has been identified as the secondary mass loader in the magnetosphere, orbiting within a neutral gas torus at ~9.38 Rj. Near Europa, Galileo magnetometer observations displayed bursty IC wave characteristics at the gyrofrequency of a number of species including SO2, K, Cl, O2, and Na, suggesting a complex mass loading environment. A particular deduction from the dataset was the presence of both positively and negatively charged pickup ions, inferred from the left and right hand polarisations of the transverse waves. Using hybrid simulations for both positively and negatively charged Cl pickup ions we are able to self-consistently reproduce the growth of both right and left hand near-circularly polarised waves in agreement with linear theory and, using the observed wave amplitudes, estimate Cl pickup ion densities at Europa.

  4. Contaminant ions and waves in the space station environment

    NASA Technical Reports Server (NTRS)

    Murphy, G. B.

    1988-01-01

    The probable plasma (ions and electrons) and plasma wave environment that will exist in the vicinity of the Space Station and how this environment may affect the operation of proposed experiments are discussed. Differences between quiescent operational periods and non-operational periods are also addressed. Areas which need further work are identified and a course of action suggested.

  5. Radiative amplification of sound waves in the winds of O and B stars

    NASA Technical Reports Server (NTRS)

    Macgregor, K. B.; Hartmann, L.; Raymond, J. C.

    1979-01-01

    The velocity perturbation associated with an outwardly propagating sound wave in a radiation-driven stellar wind gives rise to a periodic Doppler shifting of absorption lines formed in the flow. A linearized theory applicable to optically thin waves is used to show that the resulting fluctuation in the absorption-line force can cause the wave amplitude to grow. Detailed calculations of the acceleration due to a large number of lines indicate that significant amplification can occur throughout the high-velocity portion of winds in which the dominant force-producing lines have appreciable optical depths. In the particular case of the wind of Zeta Pup (O4f), it is found that the e-folding distance for wave growth is considerably shorter than the scale lengths over which the physical properties of the flow vary. A qualitative estimate of the rate at which mechanical energy due to nonlinear waves can be dissipated suggests that this mechanism may be important in heating the supersonic portion of winds of early-type stars.

  6. Solar wind implication on dust ion acoustic rogue waves

    NASA Astrophysics Data System (ADS)

    Abdelghany, A. M.; Abd El-Razek, H. N.; Moslem, W. M.; El-Labany, S. K.

    2016-06-01

    The relevance of the solar wind with the magnetosphere of Jupiter that contains positively charged dust grains is investigated. The perturbation/excitation caused by streaming ions and electron beams from the solar wind could form different nonlinear structures such as rogue waves, depending on the dominant role of the plasma parameters. Using the reductive perturbation method, the basic set of fluid equations is reduced to modified Korteweg-de Vries (KdV) and further modified (KdV) equation. Assuming that the frequency of the carrier wave is much smaller than the ion plasma frequency, these equations are transformed into nonlinear Schrödinger equations with appropriate coefficients. Rational solution of the nonlinear Schrödinger equation shows that rogue wave envelopes are supported by the present plasma model. It is found that the existence region of rogue waves depends on the dust-acoustic speed and the streaming temperatures for both the ions and electrons. The dependence of the maximum rogue wave envelope amplitude on the system parameters has been investigated.

  7. Observation of standing waves of electron-hole sound in a photoexcited semiconductor.

    PubMed

    Padmanabhan, P; Young, S M; Henstridge, M; Bhowmick, S; Bhattacharya, P K; Merlin, R

    2014-07-11

    Three-dimensional multicomponent plasmas composed of species with very different masses support a new branch of charge-density fluctuations known as acoustic plasmons. Here, we report on an ultrafast optical method to generate and probe coherent states of acoustic plasmons in a slab of GaAs, which relies on strong photoexcitation to create a large population of light electrons and heavy holes. Consistent with the random-phase-approximation theory, the data reveal standing plasma waves confined to these slabs, similar to those of conventional sound but with associated velocities that are significantly larger.

  8. Bulk ion heating with ICRF waves in tokamaks

    SciTech Connect

    Mantsinen, M. J.; Bilato, R.; Bobkov, V. V.; Kappatou, A.; McDermott, R. M.; Odstrčil, T.; Tardini, G.; Bernert, M.; Dux, R.; Maraschek, M.; Noterdaeme, J.-M.; Ryter, F.; Stober, J.; Nocente, M.; Hellsten, T.; Mantica, P.; Tardocchi, M.; Nielsen, S. K.; Rasmussen, J.; Stejner, M.; and others

    2015-12-10

    Heating with ICRF waves is a well-established method on present-day tokamaks and one of the heating systems foreseen for ITER. However, further work is still needed to test and optimize its performance in fusion devices with metallic high-Z plasma facing components (PFCs) in preparation of ITER and DEMO operation. This is of particular importance for the bulk ion heating capabilities of ICRF waves. Efficient bulk ion heating with the standard ITER ICRF scheme, i.e. the second harmonic heating of tritium with or without {sup 3}He minority, was demonstrated in experiments carried out in deuterium-tritium plasmas on JET and TFTR and is confirmed by ICRF modelling. This paper focuses on recent experiments with {sup 3}He minority heating for bulk ion heating on the ASDEX Upgrade (AUG) tokamak with ITER-relevant all-tungsten PFCs. An increase of 80% in the central ion temperature T{sub i} from 3 to 5.5 keV was achieved when 3 MW of ICRF power tuned to the central {sup 3}He ion cyclotron resonance was added to 4.5 MW of deuterium NBI. The radial gradient of the T{sub i} profile reached locally values up to about 50 keV/m and the normalized logarithmic ion temperature gradients R/LT{sub i} of about 20, which are unusually large for AUG plasmas. The large changes in the T{sub i} profiles were accompanied by significant changes in measured plasma toroidal rotation, plasma impurity profiles and MHD activity, which indicate concomitant changes in plasma properties with the application of ICRF waves. When the {sup 3}He concentration was increased above the optimum range for bulk ion heating, a weaker peaking of the ion temperature profile was observed, in line with theoretical expectations.

  9. Plasma Wave Observations during Ion Gun Experiments

    DTIC Science & Technology

    1990-03-20

    Spacecraft Charging by Magnetospheric Plasma , Progress in Aeronautics and Astronautics , Vol. 47, ed. A. Rosen, IAA, pp. 15-30 (1976). 3. H. C. Koons, P. F...AIAA 75-92 (January 20-22, 1975). 2. D. A. McPherson and W. R. Schober, " Spacecraft Charging at High Altitudes: The SCATHA Satellite Program," in...on the AF/NASI P78-2 (SCATHA) satellite were conducted with a plasma /ion source in the inner magnetosphere . These experiments were monitored with

  10. Tritium Minority Heating by Ion Bernstein Waves in Ignitor

    NASA Astrophysics Data System (ADS)

    Castaldo, C.; Cardinali, A.

    2010-11-01

    A promising scenario of minority heating of Tritium ions by Ion Bernstein Waves (IBW) coupled by mode conversion of fast waves in D(H) plasmas has been recently proposed.ootnotetextC. Castaldo and A. Cardinali, Phys. of Plasmas, in press (2010) The tritium ions are accelerated at energies high enough to increase significantly the DT fusion reactivity at relatively low temperature. It has been shown that breakeven can be reached considering a specific heating scenario for the JET machine. A similar heating scheme is analyzed for the Ignitor machine at reduced parameters. It is shown that 10 MW of ICRF power at f = 91.6 MHz, N||=3.6 that are coupled as fast waves to plasmas at BT=9 T, Ip=6 MA, ne0= 2 x10^20 m-3, Te0=Ti0=8 keV, with 25% T, 40% D, 35% H concentration, are mode converted to IBW near the D-H hybrid resonant layer and are efficiently absorbed by tritium ions via cyclotron damping at φ=2φT. The tritium ions are accelerated at energies of the order of 100 keV, where the the DT fusion reactivity peaks. As a result about 50 MW/m^3 of peak fusion power are obtained, and the expected fusion power is about 30 MW, with Q =2. The detailed comparison between equivalent scenarios in 50-50 D-T plasma is underway by means of the JETTO transport code.

  11. Plasma wave interactions with energetic ions near the magnetic equator

    NASA Technical Reports Server (NTRS)

    Gurnett, D. A.

    1976-01-01

    An intense band of electromagnetic noise is frequently observed near the magnetic equatorial plane at radial distance from about 2 to 9 earth radii. Recent wide band wave form measurements with the Imp 6 and Hawkeye 1 satellites have shown that the equatorial noise consists of a complex superposition of many harmonically spaced lines. Several distinctly different frequency spacings are often evident in the same spectrum. The frequency spacing typically ranges from a few hertz to a few tens of hertz. The purpose of this paper is to suggest that these waves are interacting with energetic protons, alpha particles, and other heavy ions trapped near the magnetic equator. The possible role that these waves play in controlling the distribution of the energetic ions is considered.

  12. Plasma wave interactions with energetic ions near the magnetic equator

    NASA Technical Reports Server (NTRS)

    Gurnett, D. A.

    1975-01-01

    An intense band of electromagnetic noise is frequently observed near the magnetic equatorial plane at radial distance from about 2 to 5 Re. Recent wideband wave-form measurements with the IMP-6 and Hawkeye-1 satellites have shown that the equatorial noise consists of a complex superposition of many harmonically spaced lines. Several distinctly different frequency spacings are often evident in the same spectrum. The frequency spacing typically ranges from a few Hz to a few tens of Hz. It is suggested that these waves are interacting with energetic protons, alpha particles, and other heavy ions trapped near the magnetic equator. The possible role these waves play in controlling the distribution of the energetic ions is considered.

  13. ARCS 3 ionospheric artificial argon ion beam injections - Waves near the heavy ion gyrofrequencies

    NASA Technical Reports Server (NTRS)

    Erlandson, R. E.; Cahill, L. J., Jr.; Kaufmann, R. L.; Arnoldy, R. L.; Pollock, C. J.

    1989-01-01

    Low-frequency electric field data below the proton gyrofrequency are presented for the duration of the argon ion beam experiment conducted as part of the Argon Release for Controlled Studies (ARCS) program. An argon ion beam was injected from the subpayload antiparallel or perpendicular to the magnetic field at altitudes from 250 to 405 km. During the injections, the wave spectra were broadband near the subpayload and narrow-band near heavy ion gyrofrequencies at perpendicular separation distances between 42 and 254 m. It is suggested that the narrow-band waves are associated with both the perpendicular argon ion beam and an unexpected flux of low-energy ions which peaked in energy near 15 eV and pitch angle near 90 deg with respect to the magnetic field.

  14. Spatial Statistics of Deep-Water Ambient Noise; Dispersion Relations for Sound Waves and Shear Waves

    DTIC Science & Technology

    2014-09-30

    published, refereed]. 24. M. J. Buckingham and M. S. Garcés, “Airborne acoustics of explosive volcanic eruptions ,” J. Comp. Acoust., 9 (3), 1215-1225...Buckingham, “On the transient solutions of three acoustic wave equations: van Wijngaarden’s equation, Stokes’ equation and the time-dependent diffusion

  15. Ion Bernstein waves in the magnetic reconnection region

    NASA Astrophysics Data System (ADS)

    Narita, Y.; Nakamura, R.; Baumjohann, W.; Glassmeier, K.-H.; Motschmann, U.; Comişel, H.

    2016-01-01

    Four-dimensional energy spectra and a diagram for dispersion relations are determined for the first time in a magnetic reconnection region in the magnetotail using data from four-spacecraft measurements by the Cluster mission on a spatial scale of 200 km, about 0.1 ion inertial lengths. The energy spectra are anisotropic with an extension in the perpendicular direction and axially asymmetric with respect to the mean magnetic field. The dispersion diagram in the plasma rest frame is in reasonably good agreement with the ion Bernstein waves at the second and higher harmonics of the proton gyrofrequency. Perpendicular-propagating ion Bernstein waves likely exist in an outflow region of magnetic reconnection, which may contribute to bifurcation of the current sheet in the outflow region.

  16. Contribution of Antisymmetric and Symmetric Waves to the Reflection of Sound in a Fluid by a Thick, Homogeneous Plate.

    DTIC Science & Technology

    1980-10-23

    SOUND IN A FLUID BY A THICK, HOMOGENEOUS PLATE INTRODUCTION In a recent report Rudgers [11 describes the acoustical behavior of thick, fluid-loaded...symmetric waves to the plate-fluid interactions studied by Rudgers (1]. In the present report, the role of antisymmetric and symmetric waves is analyzed...defined by Rudgers (4]. The structural response function of the two types of waves in combination is related to the response functions of the two types

  17. Gravitational waves from the sound of a first order phase transition.

    PubMed

    Hindmarsh, Mark; Huber, Stephan J; Rummukainen, Kari; Weir, David J

    2014-01-31

    We report on the first three-dimensional numerical simulations of first-order phase transitions in the early Universe to include the cosmic fluid as well as the scalar field order parameter. We calculate the gravitational wave (GW) spectrum resulting from the nucleation, expansion, and collision of bubbles of the low-temperature phase, for phase transition strengths and bubble wall velocities covering many cases of interest. We find that the compression waves in the fluid continue to be a source of GWs long after the bubbles have merged, a new effect not taken properly into account in previous modeling of the GW source. For a wide range of models, the main source of the GWs produced by a phase transition is, therefore, the sound the bubbles make.

  18. Transmission of singularities through a shock wave and the sound generation

    NASA Technical Reports Server (NTRS)

    Ting, L.

    1974-01-01

    The interaction of a plane shock wave of finite strength with a vortex line, point vortex, doublet or quadrupole of weak strength is studied. Based upon the physical condition that a free vortex line cannot support a pressure difference, rules are established which define the change of the linear intensity of the segment of the vortex line after its passage through the shock. The rules for point vortex, doublet, and quadrupole are then established as limiting cases. These rules can be useful for the construction of the solution of the entire flow field and for its physical interpretation. However, the solution can be obtained directly by the technique developed for shock diffraction problems. Explicit solutions and the associated sound generation are obtained for the passage of a point vortex through the shock wave.

  19. Damping of sound waves in the terahertz range and strength of the boson peak.

    PubMed

    Bove, Livia E; Petrillo, C; Fontana, A; Sokolov, A P

    2008-05-14

    By applying a new two-step line-shape analysis to inelastic neutron and x-ray scattering spectra of glassy systems, we were able to resolve the acoustic excitations from the low-frequency excess modes and to accurately estimate the damping of sound waves in the terahertz frequency range. Using this approach, we estimated the damping parameter for terahertz acoustic waves in a wide class of chemically different glasses and did a quantitative comparison of the results with prediction of theoretical models. By comparing the estimates of the mean-free path of the acoustic modes in different glasses and the corresponding boson peak strengths, we show the existence of a simple correlation between these two quantities. The relationship between attenuation of the terahertz acoustic modes, strength of the boson peak, and fragility is discussed.

  20. Do sound waves transport the AGN energy in the Perseus cluster?

    NASA Astrophysics Data System (ADS)

    Fabian, A. C.; Walker, S. A.; Russell, H. R.; Pinto, C.; Sanders, J. S.; Reynolds, C. S.

    2017-01-01

    The level of random motions in the intracluster gas lying between 20 and 60 kpc radius in the core of the Perseus cluster has been measured by the Hitomi Soft X-ray Spectrometer (SXS) at 164 ± 10 km s-1. The maximum energy density in turbulent motions on that scale is therefore low. If dissipated as heat, the turbulent energy will be radiated away in less than 80 Myr and cannot spread across the core. A higher velocity is needed to prevent a cooling collapse. Gravity waves are shown to travel too slowly in a radial direction. Here we investigate propagation of energy by sound waves. The energy travels at ˜ 1000 km s-1 and can cross the core in a cooling time. We show that the displacement velocity amplitude of the gas required to carry the power is consistent with the Hitomi result and that the inferred density and temperature variations are consistent with Chandra observations.

  1. Observationally constrained modeling of sound in curved ocean internal waves: examination of deep ducting and surface ducting at short range.

    PubMed

    Duda, Timothy F; Lin, Ying-Tsong; Reeder, D Benjamin

    2011-09-01

    A study of 400 Hz sound focusing and ducting effects in a packet of curved nonlinear internal waves in shallow water is presented. Sound propagation roughly along the crests of the waves is simulated with a three-dimensional parabolic equation computational code, and the results are compared to measured propagation along fixed 3 and 6 km source/receiver paths. The measurements were made on the shelf of the South China Sea northeast of Tung-Sha Island. Construction of the time-varying three-dimensional sound-speed fields used in the modeling simulations was guided by environmental data collected concurrently with the acoustic data. Computed three-dimensional propagation results compare well with field observations. The simulations allow identification of time-dependent sound forward scattering and ducting processes within the curved internal gravity waves. Strong acoustic intensity enhancement was observed during passage of high-amplitude nonlinear waves over the source/receiver paths, and is replicated in the model. The waves were typical of the region (35 m vertical displacement). Two types of ducting are found in the model, which occur asynchronously. One type is three-dimensional modal trapping in deep ducts within the wave crests (shallow thermocline zones). The second type is surface ducting within the wave troughs (deep thermocline zones).

  2. Wave generation by contaminant ions near a large spacecraft

    NASA Technical Reports Server (NTRS)

    Singh, N.

    1993-01-01

    Measurements from the space shuttle flights have revealed that a large spacecraft in a low earth orbit is accompanied by an extensive gas cloud which is primarily made up of water. The charge exchange between the water molecule and the ionospheric O(+) ions produces a water ion beam traversing downstream of the spacecraft. In this report we present results from a study on the generation of plasma waves by the interaction of the water ion beams with the ionospheric plasma. Since velocity distribution function is key to the understanding of the wave generation process, we have performed a test particle simulation to determine the nature of H2O(+) ions velocity distribution function. The simulations show that at the time scales shorter than the ion cyclotron period tau(sub c), the distribution function can be described by a beam. On the other hand, when the time scales are larger than tau(sub c), a ring distribution forms. A brief description of the linear instabilities driven by an ion beam streaming across a magnetic field in a plasma is presented. We have identified two types of instabilities occurring in low and high frequency bands; the low-frequency instability occurs over the frequency band from zero to about the lower hybrid frequency for a sufficiently low beam density. As the beam density increases, the linear instability occurs at decreasing frequencies below the lower-hybrid frequency. The high frequency instability occurs near the electron cyclotron frequency and its harmonics.

  3. Reconstruction of nonstationary sound fields based on the time domain plane wave superposition method.

    PubMed

    Zhang, Xiao-Zheng; Thomas, Jean-Hugh; Bi, Chuan-Xing; Pascal, Jean-Claude

    2012-10-01

    A time-domain plane wave superposition method is proposed to reconstruct nonstationary sound fields. In this method, the sound field is expressed as a superposition of time convolutions between the estimated time-wavenumber spectrum of the sound pressure on a virtual source plane and the time-domain propagation kernel at each wavenumber. By discretizing the time convolutions directly, the reconstruction can be carried out iteratively in the time domain, thus providing the advantage of continuously reconstructing time-dependent pressure signals. In the reconstruction process, the Tikhonov regularization is introduced at each time step to obtain a relevant estimate of the time-wavenumber spectrum on the virtual source plane. Because the double infinite integral of the two-dimensional spatial Fourier transform is discretized directly in the wavenumber domain in the proposed method, it does not need to perform the two-dimensional spatial fast Fourier transform that is generally used in time domain holography and real-time near-field acoustic holography, and therefore it avoids some errors associated with the two-dimensional spatial fast Fourier transform in theory and makes possible to use an irregular microphone array. The feasibility of the proposed method is demonstrated by numerical simulations and an experiment with two speakers.

  4. Statistical Analysis of Bursty Langmuir Waves, Alfvén and Whistler Waves, and Precipitating Electrons Seen by the CHARM II Nightside Sounding Rocket

    NASA Astrophysics Data System (ADS)

    Dombrowski, M. P.; Labelle, J. W.; Kletzing, C.; Bounds, S. R.; Kaeppler, S. R.

    2013-12-01

    Bursty Langmuir waves have been interpreted as the result of the superposition of multiple Langmuir normal-mode waves, with the resultant modulation being the beat pattern between waves with e.g. 10 kHz frequency differences. The normal-mode waves could be generated either through wave-wave interactions with VLF waves, or through independent linear processes. The CHARM II sounding rocket was launched into a substorm at 9:49 UT on 15 February 2010, from the Poker Flat Research Range in Alaska. The primary instruments included the Dartmouth High-Frequency Experiment (HFE), a receiver system which effectively yields continuous (100% duty cycle) E-field waveform measurements up to 5 MHz, as well as a number of charged particle detectors, including a wave-particle correlator. The payload also included a magnetometer and several low-frequency wave instruments. CHARM II encountered several regions of strong Langmuir wave activity throughout its 15-minute flight, including several hundred discrete Langmuir-wave bursts. We show results of a statistical analysis of CHARM II data for the entire flight, comparing HFE data with the other payload instruments, specifically looking at timings and correlations between bursty Langmuir waves, Alfvén and whistler-mode waves, and electrons precipitating parallel to the magnetic field. Following a similar analysis on TRICE dayside sounding rocket data, we also calculate the fraction of correlated waves with VLF waves at appropriate frequencies to support the wave-wave interaction bursty Langmuir wave generation mechanism, and compare to results from CHARM II nightside data.

  5. Illustrations and supporting texts for sound standing waves of air columns in pipes in introductory physics textbooks

    NASA Astrophysics Data System (ADS)

    Zeng, Liang; Smith, Chris; Poelzer, G. Herold; Rodriguez, Jennifer; Corpuz, Edgar; Yanev, George

    2014-12-01

    In our pilot studies, we found that many introductory physics textbook illustrations with supporting text for sound standing waves of air columns in open-open, open-closed, and closed-closed pipes inhibit student understanding of sound standing wave phenomena due to student misunderstanding of how air molecules move within these pipes. Based on the construct of meaningful learning from cognitive psychology and semiotics, a quasiexperimental study was conducted to investigate the comparative effectiveness of two alternative approaches to student understanding: a traditional textbook illustration approach versus a newly designed air molecule motion illustration approach. Thirty volunteer students from introductory physics classes were randomly assigned to two groups of 15 each. Both groups were administered a presurvey. Then, group A read the air molecule motion illustration handout, and group B read a traditional textbook illustration handout; both groups were administered postsurveys. Subsequently, the procedure was reversed: group B read the air molecule motion illustration handout and group A read the traditional textbook illustration handout. This was followed by a second postsurvey along with an exit research questionnaire. The study found that the majority of students experienced meaningful learning and stated that they understood sound standing wave phenomena significantly better using the air molecule motion illustration approach. This finding provides a method for physics education researchers to design illustrations for abstract sound standing wave concepts, for publishers to improve their illustrations with supporting text, and for instructors to facilitate deeper learning in their students on sound standing waves.

  6. Electromagnetic ion cyclotron waves observed in the plasma depletion layer

    NASA Technical Reports Server (NTRS)

    Anderson, B. J.; Fuselier, S. A.; Murr, D.

    1991-01-01

    Observations from AMPTE/CCE in the earth's magnetosheath on October 5, 1984 are presented to illustrate 0.1 - 4.0 Hz magnetic field pulsations in the subsolar plasma depletion layer (PDL) for northward sheath field during a magnetospheric compression. The PDL is unambiguously identified by comparing CCE data with data from IRM in the upstream solar wind. Pulsations in the PDL are dominated by transverse waves with F/F(H+) 1.0 or less and a slot in spectral power at F/F(H+) = 0.5. The upper branch is left hand polarized while the lower branch is linearly polarized. In the sheath the proton temperature anisotropy is about 0.6 but it is about 1.7 in the PDL during wave occurrence. The properties and correlation of waves with increased anisotropy indicate that they are electromagnetic ion cyclotron waves.

  7. Synergy between middle infrared and millimeter-wave limb sounding of atmospheric temperature and minor constituents

    NASA Astrophysics Data System (ADS)

    Cortesi, Ugo; Del Bianco, Samuele; Ceccherini, Simone; Gai, Marco; Dinelli, Bianca Maria; Castelli, Elisa; Oelhaf, Hermann; Woiwode, Wolfgang; Höpfner, Michael; Gerber, Daniel

    2016-05-01

    Synergistic exploitation of redundant and complementary information from independent observations of the same target remains a major issue in atmospheric remote sounding and increasing attention is devoted to investigate optimized or innovative methods for the combination of two or more measured data sets. This paper focuses on the synergy between middle infrared and millimeter-wave limb sounding measurements of atmospheric composition and temperature and reports the results of a study conducted as part of the preparatory activities of the PREMIER (Process Exploration through Measurements of Infrared and millimeter-wave Emitted Radiation) mission candidate to the Core Missions of the European Space Agency (ESA) Earth Explorer 7. The activity was based on data acquired by the MIPAS-STR (Michelson Interferometer for Passive Atmospheric Sounding - STRatospheric aircraft) and MARSCHALS (Millimetre-wave Airborne Receivers for Spectroscopic CHaracterisation in Atmospheric Limb Sounding) instruments on-board the high-altitude research aircraft M-55 Geophysica during the flight of the PremierEx (PREMIER Experiment) campaign on 10 March 2010 from Kiruna, Sweden, for observation of the Arctic upper troposphere and lower stratosphere. The cloud coverage observed along the flight provided representative test cases to evaluate the synergy in three different scenarios: low clouds in the first part, no clouds in the central part and high tropospheric clouds at the end. The calculation of synergistic profiles of four atmospheric targets (i.e., O3, HNO3, H2O and temperature) was performed using a posteriori combination of individual retrieved profiles, i.e., Level 2 (L2) data rather than simultaneous inversion of observed radiances, i.e., Level 1 (L1) data. An innovative method of data fusion, based on the Measurement Space Solution (MSS) was applied along with the standard approach of inversion of MARSCHALS spectral radiances using MIPAS-STR retrieval products as a priori

  8. Synergy between middle infrared and millimetre-wave limb sounding of atmospheric temperature and minor constituents

    NASA Astrophysics Data System (ADS)

    Cortesi, U.; Del Bianco, S.; Ceccherini, S.; Gai, M.; Dinelli, B. M.; Castelli, E.; Oelhaf, H.; Woiwode, W.; Höpfner, M.; Gerber, D.

    2015-11-01

    Synergistic exploitation of redundant and complementary information from independent observations of the same target remains a major issue in atmospheric remote-sounding and increasing attention is devoted to investigate optimised or innovative methods for the combination of two or more measured data sets. This paper is focusing on the synergy between middle infrared and millimetre-wave limb sounding measurements of atmospheric composition and temperature and reports the results of a study conducted as part of the preparatory activities of the PREMIER (Process Exploration through Measurements of Infrared and millimetre wave Emitted Radiation) mission candidate to the Core Missions of ESA Earth Explorer 7. The activity was based on data acquired by the MIPAS-STR (Michelson Interferometer for Passive Atmospheric Sounding - STRatospheric aircraft) and MARSCHALS (Millimetre-wave Airborne Receivers for Spectroscopic CHaracterisation in Atmospheric Limb Sounding) instruments onboard the high altitude research aircraft M-55 Geophysica during the flight of the PremierEx (PREMIER Experiment) campaign on 10 March 2010 from Kiruna, Sweden for observation of the Arctic upper troposphere and lower stratosphere. The cloud coverage observed along the flight provided representative test cases to evaluate the synergy in three different scenarios: low clouds in the first part, no clouds in the central part and high tropospheric clouds at the end. The calculation of synergistic profiles of four atmospheric targets (i.e., O2, HNO3, H2O and temperature) was performed using a posteriori combination of individual retrieved profiles, i.e., Level 2 (L2) data rather than simultaneous inverse processing of observed radiances, i.e., Level 1 (L1) data. An innovative method of data fusion, based on the Measurement Space Solution (MSS) was applied along with the standard approach of inverse processing of MARSCHALS spectral radiances using MIPAS-STR retrieval products as a priori information (L1

  9. Sound-wave coherence in atmospheric turbulence with intrinsic and global intermittency.

    PubMed

    Wilson, D Keith; Ostashev, Vladimir E; Goedecke, George H

    2008-08-01

    The coherence function of sound waves propagating through an intermittently turbulent atmosphere is calculated theoretically. Intermittency mechanisms due to both the turbulent energy cascade (intrinsic intermittency) and spatially uneven production (global intermittency) are modeled using ensembles of quasiwavelets (QWs), which are analogous to turbulent eddies. The intrinsic intermittency is associated with decreasing spatial density (packing fraction) of the QWs with decreasing size. Global intermittency is introduced by allowing the local strength of the turbulence, as manifested by the amplitudes of the QWs, to vary in space according to superimposed Markov processes. The resulting turbulence spectrum is then used to evaluate the coherence function of a plane sound wave undergoing line-of-sight propagation. Predictions are made by a general simulation method and by an analytical derivation valid in the limit of Gaussian fluctuations in signal phase. It is shown that the average coherence function increases as a result of both intrinsic and global intermittency. When global intermittency is very strong, signal phase fluctuations become highly non-Gaussian and the average coherence is dominated by episodes with weak turbulence.

  10. Adaptive wave field synthesis for broadband active sound field reproduction: signal processing.

    PubMed

    Gauthier, Philippe-Aubert; Berry, Alain

    2008-04-01

    Sound field reproduction is a physical approach to the reproduction of the natural spatial character of hearing. It is also useful in experimental acoustics and psychoacoustics. Wave field synthesis (WFS) is a known open-loop technology which assumes that the reproduction environment is anechoic. A real reflective reproduction space thus reduces the objective accuracy of WFS. Recently, adaptive wave field synthesis (AWFS) was defined as a combination of WFS and active compensation. AWFS is based on the minimization of reproduction errors and on the penalization of departure from the WFS solution. This paper focuses on signal processing for AWFS. A classical adaptive algorithm is modified for AWFS: filtered-reference least-mean-square. This modified algorithm and the classical equivalent leaky algorithm have similar convergence properties except that the WFS solution influences the adaptation rule of the modified algorithm. The paper also introduces signal processing for independent radiation mode control of AWFS on the basis of plant decoupling. Simulation results for AWFS are introduced for free-field and reflective spaces. The two algorithms effectively reproduce the sound field and compensate for the reproduction errors at the error sensors. The independent radiation mode control allows a more flexible tuning of the algorithm.

  11. CWIS Experiment On Board REXUS-16 Sounding Rocket: Investigation of the Chemical Wave in Binary Mixture

    NASA Astrophysics Data System (ADS)

    Tzevelecos, W.; Pugliese, A.; de Filippis, L.; Manzone, S.; Alfano, B.; Mancino, F.; Runge, W.; Desenfans, O.; Galand, Q.; Van Vaerenbergh, S.

    2015-09-01

    Chemical Wave in Soret Effect (CWIS) is an experiment launched in May 2014 on-board a REXUS sounding rocket from Esrange Space Center. The experiment was completely designed and assembled by students from different countries under an international collaboration between the Université libre de Bruxelles (ULB) and the University of Naples Federico II. This student program called REXUS/BEXUS allows students to perform experiments in space science applications under the supervision of the European Space Agency (ESA). The objective of the CWIS Team was to visualize the Chemical Wave (CW) during the transient of the Soret effect. The CW is a concentration front that rapidly propagates under thermal gradient in a liquid mixture, and which marks the beginning of the chemical separation phenomenon by thermodiffusion (the separation process is itself named Soret effect, but is usually analyzed statically). The selected mixture was a solution of Ethylene Glycol in Water and concentration variation due to thermal gradients was recorded using a modified Fizeau interferometer, with modifications designed to enlarge a very small region of the test cell using cylindrical squeezing. We recorded more than 100 images with the chemical information and in this paper work we will show the final results of the sounding rocket experiment.

  12. Using second-sound shock waves to probe the intrinsic critical velocity of liquid helium II

    NASA Technical Reports Server (NTRS)

    Turner, T. N.

    1983-01-01

    A critical velocity truly intrinsic to liquid helium II is experimentally sought in the bulk fluid far from the apparatus walls. Termed the 'fundamental critical velocity,' it necessarily is caused by mutual interactions which operate between the two fluid components and which are activated at large relative velocities. It is argued that flow induced by second-sound shock waves provides the ideal means by which to activate and isolate the fundamental critical velocity from other extraneous fluid-wall interactions. Experimentally it is found that large-amplitude second-sound shock waves initiate a breakdown in the superfluidity of helium II, which is dramatically manifested as a limit to the maximum attainable shock strength. This breakdown is shown to be caused by a fundamental critical velocity. Secondary effects include boiling for ambient pressures near the saturated vapor pressure or the formation of helium I boundary layers at higher ambient pressures. When compared to the intrinsic critical velocity discovered in highly restricted geometries, the shock-induced critical velocity displays a similar temperature dependence and is the same order of magnitude.

  13. Sound waves generated due to the absorption of a pulsed electron beam in gas

    NASA Astrophysics Data System (ADS)

    Pushkarev, A. I.; Pushkarev, M. A.; Remnev, G. E.

    2002-03-01

    The results of an experimental investigation of acoustic vibrations (their frequency, amplitude, and attenuation coefficient) generated in a gas mixture as a result of the injection of a high-current pulsed electron beam into a closed reactor are presented. It is shown that the change in the phase composition of the initial mixture under the action of the electron beam leads to a change in the frequency of the sound waves and to an increase in the attenuation coefficient. By measuring the change in frequency, it is possible to evaluate with sufficient accuracy (about 2%) the degree of conversion of the initial products in the plasmochemical process. Relations describing the dependence of the sound energy attenuation coefficient on the size of the reactor and on the thermal and physical properties of the gases under study are derived. It is shown that a simple experimental setup measuring the parameters of acoustic waves can be used for monitoring the plasmochemical processes initiated by a pulsed excitation of a gas mixture.

  14. Active listening room compensation for massive multichannel sound reproduction systems using wave-domain adaptive filtering.

    PubMed

    Spors, Sascha; Buchner, Herbert; Rabenstein, Rudolf; Herbordt, Wolfgang

    2007-07-01

    The acoustic theory for multichannel sound reproduction systems usually assumes free-field conditions for the listening environment. However, their performance in real-world listening environments may be impaired by reflections at the walls. This impairment can be reduced by suitable compensation measures. For systems with many channels, active compensation is an option, since the compensating waves can be created by the reproduction loudspeakers. Due to the time-varying nature of room acoustics, the compensation signals have to be determined by an adaptive system. The problems associated with the successful operation of multichannel adaptive systems are addressed in this contribution. First, a method for decoupling the adaptation problem is introduced. It is based on a generalized singular value decomposition and is called eigenspace adaptive filtering. Unfortunately, it cannot be implemented in its pure form, since the continuous adaptation of the generalized singular value decomposition matrices to the variable room acoustics is numerically very demanding. However, a combination of this mathematical technique with the physical description of wave propagation yields a realizable multichannel adaptation method with good decoupling properties. It is called wave domain adaptive filtering and is discussed here in the context of wave field synthesis.

  15. Effect of sound wave stress on antioxidant enzyme activities and lipid peroxidation of Dendrobium candidum.

    PubMed

    Li, Biao; Wei, Jinmin; Wei, Xiaolan; Tang, Kun; Liang, Yilong; Shu, Kunxian; Wang, Bochu

    2008-06-01

    The effect of sound wave stress on important medicinal plant, Dendrobium candidum Wall. ex Lindl, was investigated, including the responses on malondialdehyde (MDA) content, the activities change of superoxide dismutase (SOD), catalase (CAT), peroxidase (POD) and ascorbate peroxidase (APX). Results were found that the activities of SOD, CAT, POD and APX enhanced totally in different organs of D. candidum, as leaves, stems and roots, in response to the stress. Furthermore there happened similar shift of antioxidant enzymes activities, which increased in the initial stimulation and decreased afterwards. Data showed SOD, CAT, POD and APX activities ascended to max at day 9, 6, 9 and 12 in leaves, at day 9, 6, 12 and 9 in stems, and at day 12, 6, 9 and 9 in roots, respectively. As a lipid peroxidation parameter, MDA content in different organs increased in the beginning, dropped afterward, and increased again in the late. Anyway the total trend was the rise of MDA level compared to the control. It was interesting that the MDA content appeared the lowest levels almost when the antioxidant enzymes activities were up to the highest. Our results demonstrated the different organs of D. candidum might produce accumulation of active oxygen species (AOS) under initial treatment of sound wave stress. Later AOS might start to reduce due to the enhancement of antioxidant enzymes activities treated by the stress. The data revealed that the antioxidant metabolism was to be important in determining the ability of plants to survive in sound stress, and the up regulation of these enzymes activities would help to reduce the build up of AOS, which could protect plant cells from oxidative damage. Moreover, different cell compartments might activate different defensive system to reduce excessive amount of AOS. Finally the mechanism of this action was also discussed simply.

  16. Character, distribution, and ecological significance of storm wave-induced scour in Rhode Island Sound, USA

    NASA Astrophysics Data System (ADS)

    McMullen, Katherine Y.; Poppe, Lawrence J.; Parker, Castle E.

    2015-04-01

    Multibeam bathymetry, collected during NOAA hydrographic surveys in 2008 and 2009, is coupled with USGS data from sampling and photographic stations to map the seabed morphology and composition of Rhode Island Sound along the US Atlantic coast, and to provide information on sediment transport and benthic habitats. Patchworks of scour depressions cover large areas on seaward-facing slopes and bathymetric highs in the sound. These depressions average 0.5-0.8 m deep and occur in water depths reaching as much as 42 m. They have relatively steep well-defined sides and coarser-grained floors, and vary strongly in shape, size, and configuration. Some individual scour depressions have apparently expanded to combine with adjacent depressions, forming larger eroded areas that commonly contain outliers of the original seafloor sediments. Where cobbles and scattered boulders are present on the depression floors, the muddy Holocene sands have been completely removed and the winnowed relict Pleistocene deposits exposed. Low tidal-current velocities and the lack of obstacle marks suggest that bidirectional tidal currents alone are not capable of forming these features. These depressions are formed and maintained under high-energy shelf conditions owing to repetitive cyclic loading imposed by high-amplitude, long-period, storm-driven waves that reduce the effective shear strength of the sediment, cause resuspension, and expose the suspended sediments to erosion by wind-driven and tidal currents. Because epifauna dominate on gravel floors of the depressions and infauna are prevalent in the finer-grained Holocene deposits, it is concluded that the resultant close juxtaposition of silty sand-, sand-, and gravel-dependent communities promotes regional faunal complexity. These findings expand on earlier interpretations, documenting how storm wave-induced scour produces sorted bedforms that control much of the benthic geologic and biologic diversity in Rhode Island Sound.

  17. Character, distribution, and ecological significance of storm wave-induced scour in Rhode Island Sound, USA

    USGS Publications Warehouse

    McMullen, Katherine Y.; Poppe, Lawrence J.; Parker, Castle E.

    2015-01-01

    Multibeam bathymetry, collected during NOAA hydrographic surveys in 2008 and 2009, is coupled with USGS data from sampling and photographic stations to map the seabed morphology and composition of Rhode Island Sound along the US Atlantic coast, and to provide information on sediment transport and benthic habitats. Patchworks of scour depressions cover large areas on seaward-facing slopes and bathymetric highs in the sound. These depressions average 0.5-0.8 m deep and occur in water depths reaching as much as 42 m. They have relatively steep well-defined sides and coarser-grained floors, and vary strongly in shape, size, and configuration. Some individual scour depressions have apparently expanded to combine with adjacent depressions, forming larger eroded areas that commonly contain outliers of the original seafloor sediments. Where cobbles and scattered boulders are present on the depression floors, the muddy Holocene sands have been completely removed and the winnowed relict Pleistocene deposits exposed. Low tidal-current velocities and the lack of obstacle marks suggest that bidirectional tidal currents alone are not capable of forming these features. These depressions are formed and maintained under high-energy shelf conditions owing to repetitive cyclic loading imposed by high-amplitude, long-period, storm-driven waves that reduce the effective shear strength of the sediment, cause resuspension, and expose the suspended sediments to erosion by wind-driven and tidal currents. Because epifauna dominate on gravel floors of the depressions and infauna are prevalent in the finer-grained Holocene deposits, it is concluded that the resultant close juxtaposition of silty sand-, sand-, and gravel-dependent communities promotes regional faunal complexity. These findings expand on earlier interpretations, documenting how storm wave-induced scour produces sorted bedforms that control much of the benthic geologic and biologic diversity in Rhode Island Sound.

  18. Freak waves in negative-ion plasmas: an experiment revisited

    NASA Astrophysics Data System (ADS)

    Kourakis, Ioannis; Elkamash, Ibrahem; Reville, Brian

    2016-10-01

    Extreme events in the form of rogue waves (freak waves) occur widely in the open sea. These are space- and time-localised excitations, which appear unexpectedly and are characterised by a significant amplitude. Beyond ocean dynamics, the mechanisms underlying rogue wave formation are now being investigated in various physical contexts, including materials science, nonlinear optics and plasma physics, to mention but a few. We have undertaken an investigation, from first principles, of the occurrence of rogue waves associated with the propagation of electrostatic wavepackets in plasmas. Motivated by recent experimental considerations involving freak waves in negative-ion plasmas (NIP), we have addresed the occurrence of freak waves in NIP from first principles. An extended range of plasma parameter values was identified, where freak wave formation is possible, in terms of relevant plasma parameters. Our results extend -and partly contradict- the underlying assumptions in the interpretation of the aforementioned experiment, where a critical plasma configuration was considered and a Gardner equation approach was adopted. This work was supported from CPP/QUB funding. One of us (I. Elkamash) acknowledges financial support by an Egyptian Government fellowship.

  19. Characteristics of surface sound pressure and absorption of a finite impedance strip for a grazing incident plane wave.

    PubMed

    Sum, K S; Pan, J

    2007-07-01

    Distributions of sound pressure and intensity on the surface of a flat impedance strip flush-mounted on a rigid baffle are studied for a grazing incident plane wave. The distributions are obtained by superimposing the unperturbed wave (the specularly reflected wave as if the strip is rigid plus the incident wave) with the radiated wave from the surface vibration of the strip excited by the unperturbed pressure. The radiated pressure interferes with the unperturbed pressure and distorts the propagating plane wave. When the plane wave propagates in the baffle-strip-baffle direction, it encounters discontinuities in acoustical impedance at the baffle-strip and strip-baffle interfaces. The radiated pressure is highest around the baffle-strip interface, but decreases toward the strip-baffle interface where the plane wave distortion reduces accordingly. As the unperturbed and radiated waves have different magnitudes and superimpose out of phase, the surface pressure and intensity increase across the strip in the plane wave propagation direction. Therefore, the surface absorption of the strip is nonzero and nonuniform. This paper provides an understanding of the surface pressure and intensity behaviors of a finite impedance strip for a grazing incident plane wave, and of how the distributed intensity determines the sound absorption coefficient of the strip.

  20. Ion acoustic shock waves in plasmas with warm ions and kappa distributed electrons and positrons

    SciTech Connect

    Hussain, S.; Mahmood, S.; Hafeez Ur-Rehman

    2013-06-15

    The monotonic and oscillatory ion acoustic shock waves are investigated in electron-positron-ion plasmas (e-p-i) with warm ions (adiabatically heated) and nonthermal kappa distributed electrons and positrons. The dissipation effects are included in the model due to kinematic viscosity of the ions. Using reductive perturbation technique, the Kadomtsev-Petviashvili-Burgers (KPB) equation is derived containing dispersion, dissipation, and diffraction effects (due to perturbation in the transverse direction) in e-p-i plasmas. The analytical solution of KPB equation is obtained by employing tangent hyperbolic (Tanh) method. The analytical condition for the propagation of oscillatory and monotonic shock structures are also discussed in detail. The numerical results of two dimensional monotonic shock structures are obtained for graphical representation. The dependence of shock structures on positron equilibrium density, ion temperature, nonthermal spectral index kappa, and the kinematic viscosity of ions are also discussed.

  1. Nonlinear heavy-ion-acoustic waves in an adiabatic collisionless bi-ion plasma

    NASA Astrophysics Data System (ADS)

    Hossen, M. A.; Rahman, M. M.; Hossen, M. R.; Mamun, A. A.

    2017-03-01

    The basic properties of heavy-ion-acoustic (HIA) waves have been investigated in a collisionless plasma system which is supposed to be composed of nonthermal electrons, Boltzmann distributed light ions, and adiabatic positively charged inertial heavy ions. The Kortewg-de Vries and Burgers equations are derived in nonplanar (cylindrical and spherical) geometry by employing the standard reductive perturbation method for studying the basic features (viz. amplitude, phase speed, etc.) of HIA solitary and shock waves, which are associated with either positive or negative potential. It is found that the effects of nonplanar geometry, adiabaticity of positively charged inertial heavy ions, the presence of nonthermal (Cairns distributed) electrons, and number densities of the plasma components significantly modify the basic features of nonplanar HIA waves. It has been observed that the properties of solitary and shock waves associated with HIA waves in a nonplanar geometry differ from those in a planar geometry. The implications of our results may be helpful in understanding the electrostatic perturbations in various laboratory and astrophysical plasma environments.

  2. A Self-Consistent Model of the Interacting Ring Current Ions and Electromagnetic Ion Cyclotron Waves, Initial Results: Waves and Precipitating Fluxes

    NASA Technical Reports Server (NTRS)

    Khazanov, G. V.; Gamayunov, K. V.; Jordanova, V. K.; Krivorutsky, E. N.

    2002-01-01

    Initial results from a newly developed model of the interacting ring current ions and ion cyclotron waves are presented. The model is based on the system of two kinetic equations: one equation describes the ring current ion dynamics, and another equation describes wave evolution. The system gives a self-consistent description of the ring current ions and ion cyclotron waves in a quasilinear approach. These equations for the ion phase space distribution function and for the wave power spectral density were solved on aglobal magnetospheric scale undernonsteady state conditions during the 2-5 May 1998 storm. The structure and dynamics of the ring current proton precipitating flux regions and the ion cyclotron wave-active zones during extreme geomagnetic disturbances on 4 May 1998 are presented and discussed in detail.

  3. On the rogue wave propagation in ion pair superthermal plasma

    SciTech Connect

    Abdelwahed, H. G. E-mail: hgomaa-eg@mans.edu.eg; Zahran, M. A.; El-Shewy, E. K. Elwakil, S. A.

    2016-02-15

    Effects of superthermal electron on the features of nonlinear acoustic waves in unmagnetized collisionless ion pair plasma with superthermal electrons have been examined. The system equations are reduced in the form of the nonlinear Schrodinger equation. The rogue wave characteristics dependences on the ionic density ratio (ν = n{sub –0}/n{sub +0}), ionic mass ratio (Q = m{sub +}/m{sub −}), and superthermality index (κ) are investigated. It is worth mentioning that the results present in this work could be applicable in the Earth's ionosphere plasmas.

  4. Dust-ion acoustic cnoidal waves and associated nonlinear ion flux in a nonthermal dusty plasma

    NASA Astrophysics Data System (ADS)

    Ur-Rehman, Hafeez; Mahmood, S.

    2016-09-01

    The dust-ion acoustic nonlinear periodic (cnoidal) waves and solitons are investigated in a dusty plasma containing dynamic cold ions, superthermal kappa distributed electrons and static charged dust particles. The massive dust particles can have positive or negative charge depending on the plasma environment. Using reductive perturbation method (RPM) with appropriate periodic boundary conditions, the evolution equations for the first and second order nonlinear potentials are derived. The first order potential is determined through Korteweg-de Vries (KdV) equation which gives dust-ion acoustic cnoidal waves and solitons structures. The solution of second order nonlinear potential is obtained through an inhomogeneous differential equation derived from collecting higher order terms of dynamic equations, which is linear for second order electrostatic potential. The nonlinear ion flux associated with the cnoidal waves is also found out numerically. The numerical plots of the dust-ion acoustic cnoidal wave and soliton structures for both positively and negatively charged dust particles cases and nonthermal electrons are also presented for illustration. It is found that only compressive nonlinear electrostatic structures are formed in case of positively dust charged particles while both compressive and rarefactive nonlinear structures are obtained in case of negatively charged particles depending on the negatively charged dust density in a nonthermal dusty plasma. The numerical results are obtained using data of the ionospheric region containing dusty plasma exist in the literature.

  5. Classification of biological cells using a sound wave based flow cytometer

    NASA Astrophysics Data System (ADS)

    Strohm, Eric M.; Gnyawali, Vaskar; Van De Vondervoort, Mia; Daghighi, Yasaman; Tsai, Scott S. H.; Kolios, Michael C.

    2016-03-01

    A flow cytometer that uses sound waves to determine the size of biological cells is presented. In this system, a microfluidic device made of polydimethylsiloxane (PDMS) was developed to hydrodynamically flow focus cells in a single file through a target area. Integrated into the microfluidic device was an ultrasound transducer with a 375 MHz center frequency, aligned opposite the transducer was a pulsed 532 nm laser focused into the device by a 10x objective. Each passing cell was insonfied with a high frequency ultrasound pulse, and irradiated with the laser. The resulting ultrasound and photoacoustic waves from each cell were analyzed using signal processing methods, where features in the power spectra were compared to theoretical models to calculate the cell size. Two cell lines with different size distributions were used to test the system: acute myeloid leukemia cells (AML) and melanoma cells. Over 200 cells were measured using this system. The average calculated diameter of the AML cells was 10.4 +/- 2.5 μm using ultrasound, and 11.4 +/- 2.3 μm using photoacoustics. The average diameter of the melanoma cells was 16.2 +/- 2.9 μm using ultrasound, and 18.9 +/- 3.5 μm using photoacoustics. The cell sizes calculated using ultrasound and photoacoustic methods agreed with measurements using a Coulter Counter, where the AML cells were 9.8 +/- 1.8 μm and the melanoma cells were 16.0 +/- 2.5 μm. These results demonstrate a high speed method of assessing cell size using sound waves, which is an alternative method to traditional flow cytometry techniques.

  6. Radiation of Sound Waves Via Soliton Excitation of the Angarmonic Chain of Atoms in a Dislocation Core

    NASA Astrophysics Data System (ADS)

    Gestrin, S. G.; Shchukina, E. V.

    2016-07-01

    It is demonstrated that propagation of the soliton described by the Boussinesq equation along a linear defect of the crystal structure leads to radiation of sound waves (analog of the Vavilov-Cherenkov effect). Radiation that has a continuous spectrum diverges conically from the dislocation line, and the apex angle of the cone is determined by the ratio of the sound speed in the crystal to the soliton speed. With increasing soliton speed, the maximum of the spectral flux density of sound energy is displaced toward higher frequencies. An analytical expression for energy losses is derived.

  7. Observations of multiharmonic ion cyclotron waves due to inverse ion cyclotron damping in the northern magnetospheric cusp

    NASA Astrophysics Data System (ADS)

    Slapak, R.; Gunell, H.; Hamrin, M.

    2017-01-01

    We present a case study of inverse ion cyclotron damping taking place in the northern terrestrial magnetospheric cusp, exciting waves at the ion cyclotron frequency and its harmonics. The ion cyclotron waves are primarily seen as peaks in the magnetic-field spectral densities. The corresponding peaks in the electric-field spectral densities are not as profound, suggesting a background electric field noise or other processes of wave generation causing the electric spectral densities to smoothen out more compared to the magnetic counterpart. The required condition for inverse ion cyclotron damping is a velocity shear in the magnetic field-aligned ion bulk flow, and this condition is often naturally met for magnetosheath influx in the northern magnetospheric cusp, just as in the presented case. We note that some ion cyclotron wave activity is present in a few similar shear events in the southern cusp, which indicates that other mechanisms generating ion cyclotron waves may also be present during such conditions.

  8. Heating by waves in the ion cyclotron frequency range

    SciTech Connect

    Koch, R.

    1996-03-01

    The main aspects of heating with the fast wave in the ion cyclotron range of frequencies (ICRF) are reviewed. First, the ion cyclotron resonance mechanism, fundamental and harmonics, is examined. Then the properties of fast wave dispersion are reviewed, and the principles of minority and higher cylcotron harmonic heating are discussed. An elementary coupling model is worked out in order to outline the computation of the electrical properties of ICRF antennas. Using the simple model, the antenna radiation pattern inside the plasma is computed and the effect of phasing on the k spectrum and on the antenna radiation properties is illustrated. The quasi linear-Fokker-Planck computation of the deformation of distribution functions due to Radio-Frequency (RF) and tail formation are briefly discussed. 11 refs., 5 figs.

  9. Freja observations of electromagnetic ion cyclotron ELF waves and transverse oxygen ion acceleration on auroral field lines

    SciTech Connect

    Erlandson, R.E.; Zanetti, L.J.; Acuna, M.H.; Eliasson, L.; Boehm, M.H.; Blomberg, L.G.

    1994-08-15

    Extremely low-frequency (ELF) magnetic and electric field plasma wave emissions were recorded on 2 October 1993 on auroral field lines by the Magnetic Field Experiment during Freja orbit 4770. The ELF wave frequencies were below the local oxygen gyrofrequency (25 Hz) and between the helium and proton gyrofrequencies (100 to 400 Hz). The ELF waves, interpreted as electromagnetic ion cyclotron (EMIC) waves, were observed in a region of inverted-V-type electron precipitation. The EMIC waves were correlated over time with auroral and lower energy ({approximately} 100 eV) electrons, which are both possible sources of free energy, and also with transversely accelerated oxygen ions. The waves above the helium gyrofrequency were more closely correlated with the transverse oxygen ion acceleration than the waves below the oxygen gyrofrequency. These observations are consistent with a scenario in which electron beams generate EMIC waves, which then produce transverse oxygen ion acceleration through a gyroresonant interaction. 16 refs., 4 figs.

  10. Characterization of Traveling Wave Ion Mobility Separations in Structures for Lossless Ion Manipulations.

    PubMed

    Hamid, Ahmed M; Ibrahim, Yehia M; Garimella, Sandilya V B; Webb, Ian K; Deng, Liulin; Chen, Tsung-Chi; Anderson, Gordon A; Prost, Spencer A; Norheim, Randolph V; Tolmachev, Aleksey V; Smith, Richard D

    2015-11-17

    We report on the development and characterization of a traveling wave (TW)-based Structures for Lossless Ion Manipulations (TW-SLIM) module for ion mobility separations (IMS). The TW-SLIM module uses parallel arrays of rf electrodes on two closely spaced surfaces for ion confinement, where the rf electrodes are separated by arrays of short electrodes, and using these TWs can be created to drive ion motion. In this initial work, TWs are created by the dynamic application of dc potentials. The capabilities of the TW-SLIM module for efficient ion confinement, lossless ion transport, and ion mobility separations at different rf and TW parameters are reported. The TW-SLIM module is shown to transmit a wide mass range of ions (m/z 200-2500) utilizing a confining rf waveform (∼1 MHz and ∼300 Vp-p) and low TW amplitudes (<20 V). Additionally, the short TW-SLIM module achieved resolutions comparable to existing commercially available low pressure IMS platforms and an ion mobility peak capacity of ∼32 for TW speeds of <210 m/s. TW-SLIM performance was characterized over a wide range of rf and TW parameters and demonstrated robust performance. The combined attributes of the flexible design and low voltage requirements for the TW-SLIM module provide a basis for devices capable of much higher resolution and more complex ion manipulations.

  11. Characterization of Traveling Wave Ion Mobility Separations in Structures for Lossless Ion Manipulations

    DOE PAGES

    Hamid, Ahmed M.; Ibrahim, Yehia M.; Garimella, Venkata BS; ...

    2015-10-28

    We report on the development and characterization of a new traveling wave-based Structure for Lossless Ion Manipulations (TW-SLIM) for ion mobility separations (IMS). The TW-SLIM module uses parallel arrays of rf electrodes on two closely spaced surfaces for ion confinement, where the rf electrodes are separated by arrays of short electrodes, and using these TWs can be created to drive ion motion. In this initial work, TWs are created by the dynamic application of dc potentials. The capabilities of the TW-SLIM module for efficient ion confinement, lossless ion transport, and ion mobility separations at different rf and TW parameters aremore » reported. The TW-SLIM module is shown to transmit a wide mass range of ions (m/z 200–2500) utilizing a confining rf waveform (~1 MHz and ~300 Vp-p) and low TW amplitudes (<20 V). Additionally, the short TW-SLIM module achieved resolutions comparable to existing commercially available low pressure IMS platforms and an ion mobility peak capacity of ~32 for TW speeds of <210 m/s. TW-SLIM performance was characterized over a wide range of rf and TW parameters and demonstrated robust performance. In conclusion, the combined attributes of the flexible design and low voltage requirements for the TW-SLIM module provide a basis for devices capable of much higher resolution and more complex ion manipulations.« less

  12. Characterization of Traveling Wave Ion Mobility Separations in Structures for Lossless Ion Manipulations

    SciTech Connect

    Hamid, Ahmed M.; Ibrahim, Yehia M.; Garimella, Venkata BS; Webb, Ian K.; Deng, Liulin; Chen, Tsung-Chi; Anderson, Gordon A.; Prost, Spencer A.; Norheim, Randolph V.; Tolmachev, Aleksey V.; Smith, Richard D.

    2015-10-28

    We report on the development and characterization of a new traveling wave-based Structure for Lossless Ion Manipulations (TW-SLIM) for ion mobility separations (IMS). The TW-SLIM module uses parallel arrays of rf electrodes on two closely spaced surfaces for ion confinement, where the rf electrodes are separated by arrays of short electrodes, and using these TWs can be created to drive ion motion. In this initial work, TWs are created by the dynamic application of dc potentials. The capabilities of the TW-SLIM module for efficient ion confinement, lossless ion transport, and ion mobility separations at different rf and TW parameters are reported. The TW-SLIM module is shown to transmit a wide mass range of ions (m/z 200–2500) utilizing a confining rf waveform (~1 MHz and ~300 Vp-p) and low TW amplitudes (<20 V). Additionally, the short TW-SLIM module achieved resolutions comparable to existing commercially available low pressure IMS platforms and an ion mobility peak capacity of ~32 for TW speeds of <210 m/s. TW-SLIM performance was characterized over a wide range of rf and TW parameters and demonstrated robust performance. In conclusion, the combined attributes of the flexible design and low voltage requirements for the TW-SLIM module provide a basis for devices capable of much higher resolution and more complex ion manipulations.

  13. Shaken, then stirred: The interaction of sound waves with X-ray cavities and bubbles in galaxy clusters

    NASA Astrophysics Data System (ADS)

    Heinz, Sebastian

    2008-09-01

    We propose to investigate the complex interaction of sound waves with bubbles and filaments of radio plasma in the inhomogeneous intracluster medium. This interaction is important for dissipating wave energy (thus heating cooling flow atmospheres) and creating a complex, turbulent, multiphase mixture of gas in the wake of the waves that can severely affect the X-ray appearance of clusters. Our planned program of 3D hydro and MHD simulations will investigate the role that shock wave/bubble interactions play in shaping the X-ray emitting atmospheres of galaxy clusters observed with Chandra.

  14. Sound waves effectively assist tobramycin in elimination of Pseudomonas aeruginosa biofilms in vitro.

    PubMed

    Bandara, H M H N; Harb, A; Kolacny, D; Martins, P; Smyth, H D C

    2014-12-01

    Microbial biofilms are highly refractory to antimicrobials. The aim of this study was to investigate the use of low-frequency vibration therapy (20-20 kHz) on antibiotic-mediated Pseudomonas aeruginosa biofilm eradication. In screening studies, low-frequency vibrations were applied on model biofilm compositions to identify conditions in which surface standing waves were observed. Alginate surface tension and viscosity were also measured. The effect of vibration on P. aeruginosa biofilms was studied using a standard biofilm assay. Subminimal inhibitory concentrations (sub-MIC) of tobramycin (5 μg/ml) were added to biofilms 3 h prior, during, and immediately after vibration and quantitatively assessed by (2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide) reduction assay (XTT) and, qualitatively, by confocal laser scanning microscopy (CLSM). The standing waves occurred at frequencies <1,000 Hz. Biofilms vibrated without sub-MIC tobramycin showed a significantly reduced metabolism compared to untreated controls (p < 0.05). Biofilms treated with tobramycin and vibrated simultaneously (450, 530, 610, and 650 Hz), or vibrated (450 and 650 Hz) then treated with tobramycin subsequently, or vibrated (610 Hz, 650 Hz) after 3 h of tobramycin treatment showed significantly lower metabolism compared to P. aeruginosa biofilm treated with tobramycin alone (p < 0.05). CLSM imaging further confirmed these findings. Low frequency vibrations assisted tobramycin in killing P. aeruginosa biofilms at sub-MIC. Thus, sound waves together with antibiotics are a promising approach in eliminating pathogenic biofilms.

  15. Resonance of relativistic electrons with electromagnetic ion cyclotron waves

    DOE PAGES

    Denton, R. E.; Jordanova, V. K.; Bortnik, J.

    2015-06-29

    Relativistic electrons have been thought to more easily resonate with electromagnetic ion cyclotron EMIC waves if the total density is large. We show that, for a particular EMIC mode, this dependence is weak due to the dependence of the wave frequency and wave vector on the density. A significant increase in relativistic electron minimum resonant energy might occur for the H band EMIC mode only for small density, but no changes in parameters significantly decrease the minimum resonant energy from a nominal value. The minimum resonant energy depends most strongly on the thermal velocity associated with the field line motionmore » of the hot ring current protons that drive the instability. High density due to a plasmasphere or plasmaspheric plume could possibly lead to lower minimum resonance energy by causing the He band EMIC mode to be dominant. We demonstrate these points using parameters from a ring current simulation.« less

  16. Resonance of relativistic electrons with electromagnetic ion cyclotron waves

    SciTech Connect

    Denton, R. E.; Jordanova, V. K.; Bortnik, J.

    2015-06-29

    Relativistic electrons have been thought to more easily resonate with electromagnetic ion cyclotron EMIC waves if the total density is large. We show that, for a particular EMIC mode, this dependence is weak due to the dependence of the wave frequency and wave vector on the density. A significant increase in relativistic electron minimum resonant energy might occur for the H band EMIC mode only for small density, but no changes in parameters significantly decrease the minimum resonant energy from a nominal value. The minimum resonant energy depends most strongly on the thermal velocity associated with the field line motion of the hot ring current protons that drive the instability. High density due to a plasmasphere or plasmaspheric plume could possibly lead to lower minimum resonance energy by causing the He band EMIC mode to be dominant. We demonstrate these points using parameters from a ring current simulation.

  17. Propagation of ion acoustic shock waves in negative ion plasmas with nonextensive electrons

    SciTech Connect

    Hussain, S.; Akhtar, N.; Mahmood, S.

    2013-09-15

    Nonlinear ion acoustic shocks (monotonic as well as oscillatory) waves in negative ion plasmas are investigated. The inertialess electron species are assumed to be nonthermal and follow Tsallis distribution. The dissipation in the plasma is considered via kinematic viscosities of both positive and negative ion species. The Korteweg-de Vries Burgers (KdVB) equation is derived using small amplitude reductive perturbation technique and its analytical solution is presented. The effects of variation of density and temperature of negative ions and nonthermal parameter q of electrons on the strength of the shock structures are plotted for illustration. The numerical solutions of KdVB equation using Runge Kutta method are obtained, and transition from oscillatory to monotonic shock structures is also discussed in detail for negative ions nonthermal plasmas.

  18. Accessibility condition of wave propagation and multicharged ion production in electron cyclotron resonance ion source plasma

    SciTech Connect

    Kato, Yushi Yano, Keisuke; Nishiokada, Takuya; Nagaya, Tomoki; Kimura, Daiju; Kumakura, Sho; Imai, Youta; Hagino, Shogo; Otsuka, Takuro; Sato, Fuminobu

    2016-02-15

    A new tandem type source of electron cyclotron resonance (ECR) plasmas has been constructing for producing synthesized ion beams in Osaka University. Magnetic mirror field configuration with octupole magnets can be controlled to various shape of ECR zones, namely, in the 2nd stage plasma to be available by a pair mirror and a supplemental coil. Noteworthy correlations between these magnetic configurations and production of multicharged ions are investigated in detail, as well as their optimum conditions. We have been considering accessibility condition of electromagnetic and electrostatic waves propagating in ECR ion source plasma, and then investigated their correspondence relationships with production of multicharged ions. It has been clarified that there exits efficient configuration of ECR zones for producing multicharged ion beams experimentally, and then has been suggested from detail accessibility conditions on the ECR plasma that new resonance, i.e., upper hybrid resonance, must have occurred.

  19. Accessibility condition of wave propagation and multicharged ion production in electron cyclotron resonance ion source plasma.

    PubMed

    Kato, Yushi; Yano, Keisuke; Nishiokada, Takuya; Nagaya, Tomoki; Kimura, Daiju; Kumakura, Sho; Imai, Youta; Hagino, Shogo; Otsuka, Takuro; Sato, Fuminobu

    2016-02-01

    A new tandem type source of electron cyclotron resonance (ECR) plasmas has been constructing for producing synthesized ion beams in Osaka University. Magnetic mirror field configuration with octupole magnets can be controlled to various shape of ECR zones, namely, in the 2nd stage plasma to be available by a pair mirror and a supplemental coil. Noteworthy correlations between these magnetic configurations and production of multicharged ions are investigated in detail, as well as their optimum conditions. We have been considering accessibility condition of electromagnetic and electrostatic waves propagating in ECR ion source plasma, and then investigated their correspondence relationships with production of multicharged ions. It has been clarified that there exits efficient configuration of ECR zones for producing multicharged ion beams experimentally, and then has been suggested from detail accessibility conditions on the ECR plasma that new resonance, i.e., upper hybrid resonance, must have occurred.

  20. Latitudinal dependence of nonlinear interaction between electromagnetic ion cyclotron wave and terrestrial ring current ions

    SciTech Connect

    Su, Zhenpeng Zhu, Hui; Zheng, Huinan; Xiao, Fuliang; Zhang, Min; Liu, Y. C.-M.; Shen, Chao; Wang, Yuming; Wang, Shui

    2014-05-15

    Electromagnetic ion cyclotron (EMIC) waves can lead to the rapid decay (on a timescale of hours) of the terrestrial ring current. Such decay process is usually investigated in the framework of quasi-linear theory. Here, both theoretical analysis and test-particle simulation are performed to understand the nonlinear interaction between ring current ions and EMIC waves. In particular, the dependence of the nonlinear wave-particle interaction processes on the ion initial latitude is investigated in detail. These nonlinear processes are classified into the phase trapping and phase bunching, and the phase bunching is further divided into the channel and cluster effects. Compared to the prediction of the quasi-linear theory, the ring current decay rate can be reduced by the phase trapping, increased by the channel effect phase bunching, but non-deterministically influenced by the cluster effect phase bunching. The ion initial latitude changes the occurrence of the phase trapping, modulates the transport direction and strength of the cluster effect phase bunching, and only slightly affects the channel effect phase bunching. The current results suggest that the latitudinal dependence of these nonlinear processes should be considered in the evaluation of the ring current decay induced by EMIC waves.

  1. Ion streaming instabilities with application to collisionless shock wave structure

    NASA Technical Reports Server (NTRS)

    Golden, K. I.; Linson, L. M.; Mani, S. A.

    1973-01-01

    The electromagnetic dispersion relation for two counterstreaming ion beams of arbitrary relative strength flowing parallel to a dc magnetic field is derived. The beams flow through a stationary electron background and the dispersion relation in the fluid approximation is unaffected by the electron thermal pressure. The dispersion relation is solved with a zero net current condition applied and the regions of instability in the k-U space (U is the relative velocity between the two ion beams) are presented. The parameters are then chosen to be applicable for parallel shocks. It was found that unstable waves with zero group velocity in the shock frame can exist near the leading edge of the shock for upstream Alfven Mach numbers greater than 5.5. It is suggested that this mechanism could generate sufficient turbulence within the shock layer to scatter the incoming ions and create the required dissipation for intermediate strength shocks.

  2. Ion streaming instabilities with application to collisionless shock wave structure

    NASA Technical Reports Server (NTRS)

    Golden, K. I.; Linson, L. M.; Mani, S. A.

    1973-01-01

    The electromagnetic dispersion relation for two counterstreaming ion beams of arbitrary relative strength flowing parallel to a dc magnetic field is derived. The beams flow through a stationary electron background and the dispersion relation in the fluid approximation is unaffected by the electron thermal pressure. Magnetic effects on the ion beams are included, but the electrons are treated as a magnetized fluid. The dispersion relation is solved with a zero net current condition applied and the regions of instability in the k-U space (U is the relative velocity between the two ion beams) are presented. These results are extensions of Kovner's analysis for weak beams. The parameters are then chosen to be applicable for parallel shocks. It is found that unstable waves with zero group velocity in the shock frame can exist near the leading edge of the shock for upstream Alfven Mach numbers greater than 5.5.

  3. Stabilized platform for tethered balloon soundings of broadband long- and short-wave radiation

    SciTech Connect

    Alzheimer, J.M.; Anderson, G.A.; Whiteman, C.D.

    1993-01-01

    Changes in the composition of trace gases in the earth`s atmosphere have been reported by many observers, and a general concern has been expressed regarding possible changes to the earth`s climate that may be caused by radiatively active gases introduced into the earth`s atmosphere by man`s activities. Radiatively active trace gases produce temperature changes in the earth`s atmosphere through changes in radiative flux divergence. Our knowledge of and means of measuring radiative flux divergence is very limited. A few observations of vertical radiative flux divergences have been reported from aircraft from radiometersondes from towers and from large tethered balloons. These measurement techniques suffers from one or more drawbacks, including shallow sounding depths (towers), high cost (aircraft), complicated logistics (large tethered balloons), and limitation to nighttime hours (radiometersondes). Changes in radiative flux divergence caused by anthropogenic trace gases are expected to be quite small, and will be difficult to measure with existing broadband radiative flux instruments. The emphasis of present research in global climate change is thus being focused on improving radiative transfer algorithms in global climate models. The radiative parameterizations in these models are at an early stage of development and information is needed regarding their performance, especially in cloudy conditions. The impetus for the research reported in this paper is the need for a device that can supplement existing means of measuring vertical profiles of long- and short-wave irradiance and radiative flux divergence. We have designed a small tethered-balloon-based system that can make radiometric soundings through the atmospheric boundary layer. This paper discusses the concept, the design considerations, and the design and construction of this sounding system. The performance of the system will be tested in a series of balloon flights scheduled for the fall and winter of 1992.

  4. Stabilized platform for tethered balloon soundings of broadband long- and short-wave radiation

    SciTech Connect

    Alzheimer, J.M.; Anderson, G.A.; Whiteman, C.D.

    1993-01-01

    Changes in the composition of trace gases in the earth's atmosphere have been reported by many observers, and a general concern has been expressed regarding possible changes to the earth's climate that may be caused by radiatively active gases introduced into the earth's atmosphere by man's activities. Radiatively active trace gases produce temperature changes in the earth's atmosphere through changes in radiative flux divergence. Our knowledge of and means of measuring radiative flux divergence is very limited. A few observations of vertical radiative flux divergences have been reported from aircraft from radiometersondes from towers and from large tethered balloons. These measurement techniques suffers from one or more drawbacks, including shallow sounding depths (towers), high cost (aircraft), complicated logistics (large tethered balloons), and limitation to nighttime hours (radiometersondes). Changes in radiative flux divergence caused by anthropogenic trace gases are expected to be quite small, and will be difficult to measure with existing broadband radiative flux instruments. The emphasis of present research in global climate change is thus being focused on improving radiative transfer algorithms in global climate models. The radiative parameterizations in these models are at an early stage of development and information is needed regarding their performance, especially in cloudy conditions. The impetus for the research reported in this paper is the need for a device that can supplement existing means of measuring vertical profiles of long- and short-wave irradiance and radiative flux divergence. We have designed a small tethered-balloon-based system that can make radiometric soundings through the atmospheric boundary layer. This paper discusses the concept, the design considerations, and the design and construction of this sounding system. The performance of the system will be tested in a series of balloon flights scheduled for the fall and winter of 1992.

  5. Study of Interactions Between ULF Waves and Ring Current Heavy (He+ and O+) Ions

    NASA Astrophysics Data System (ADS)

    Kim, H.; Lanzerotti, L. J.; Gerrard, A. J.; Manweiler, J. W.; Soto-chavez, A. R.; Cohen, R. J.; Bortnik, J.; Kim, E. H.; Johnson, J.

    2015-12-01

    We report the spatiotemporal structure of interactions between ULF waves and ring current heavy (He+ and O+) ions using a suite of Van Allen Probes instruments. It is well known that although heavy ions constitute only a fraction of magnetospheric particles in most conditions (especially during quiet times), their role in wave generation and propagation is significant. The relative contribution of each heavy ion species to ULF wave generation and propagation still needs to be further investigated to understand ring current heavy ion dynamics. We present data from the ion composition (Radiation Belt Storm Probes Ion Composition Experiment; RBSPICE) and field (Electric and Magnetic Field Instrument Suite and Integrated Science; EMFISIS) instruments onboard Van Allen Probes to examine ULF wave activity in the presence of heavy ions and the scattering of heavy ions. Ground-based data near spacecraft conjunction sites are also used to investigate wave propagation associated with wave-particle interactions.

  6. Dust ion-acoustic solitary waves in a dusty plasma with positive and negative ions

    SciTech Connect

    Sayed, F.; Haider, M. M.; Mamun, A. A.; Shukla, P. K.; Eliasson, B.; Adhikary, N.

    2008-06-15

    Properties of small but finite amplitude dust ion-acoustic (DIA) solitary waves in a dusty plasma composed of inertialess electrons, positive and negative inertial ions, and immobile negative/positive charged dust grains are investigated. By using the multifluid dusty plasma model, the Kortweg-de Vries equation and energy integral for small and large amplitude solitary pulses, are derived. It is found that the presence of the negative ions modifies the properties of the solitary DIA waves, and provides the possibility of positive and negative solitary potential structures to coexist. The present results may be useful for understanding the salient features of localized DIA excitations that may appear in data from forthcoming laboratory experiments and space observations.

  7. Propagation and linear mode conversion of magnetosonic and electromagnetic ion cyclotron waves in the radiation belts

    NASA Astrophysics Data System (ADS)

    Horne, Richard B.; Miyoshi, Yoshizumi

    2016-10-01

    Magnetosonic waves and electromagnetic ion cyclotron (EMIC) waves are important for electron acceleration and loss from the radiation belts. It is generally understood that these waves are generated by unstable ion distributions that form during geomagnetically disturbed times. Here we show that magnetosonic waves could be a source of EMIC waves as a result of propagation and a process of linear mode conversion. The converse is also possible. We present ray tracing to show how magnetosonic (EMIC) waves launched with large (small) wave normal angles can reach a location where the wave normal angle is zero and the wave frequency equals the so-called crossover frequency whereupon energy can be converted from one mode to another without attenuation. While EMIC waves could be a source of magnetosonic waves below the crossover frequency, magnetosonic waves could be a source of hydrogen band waves but not helium band waves.

  8. Characteristics of ion Bernstein wave heating in JIPPT-II-U tokamak

    SciTech Connect

    Okamoto, M.; Ono, M.

    1985-11-01

    Using a transport code combined with an ion Bernstein wave tokamak ray tracing code, a modelling code for the ion Bernstein wave heating has been developed. Using this code, the ion Bernstein wave heating experiment on the JIPPT-II-U tokamak has been analyzed. It is assumed that the resonance layer is formed by the third harmonic of deuterium-like ions, such as fully ionized carbon, and oxygen ions near the plasma center. For wave absorption mechanisms, electron Landau damping, ion cyclotron harmonic damping, and collisional damping are considered. The characteristics of the ion Bernstein wave heating experiment, such as the ion temperature increase, the strong dependence of the quality factor on the magnetic field strength, and the dependence of the ion temperature increment on the input power, are well reproduced.

  9. W-type ion-acoustic solitary waves in plasma consisting of cold ions and nonthermal electrons

    NASA Astrophysics Data System (ADS)

    Paul, I.; Chandra, S.; Chattopadhyay, S.; Paul, S. N.

    2016-10-01

    Sagdeev potential approach is used for the study of nonlinear propagation of ion-acoustic waves in plasma consisting of cold positive ions and nonthermal electrons. The nonlinear equation so derived are analysed with the help of Bogoliubov-Mitropolosky method. The profiles of Sagdeev potential solitary waves are evaluated in first-, second- and third- order which are depicted for different values of nonthermal parameter of electrons. It is seen that nonthermal electrons has considerable impact on the shape of ion-acoustic solitary waves in each order. The plasma consisting of cold positive ions and no negative ions can support the formation of compressive as well as W-type solitary waves in second- and third- order for certain value of nonthermal parameter of electrons. The results are new because W-type ion-acoustic solitary wave is found by earlier authors in plasma in presence of negative ions only. The ion-acoustic solitary waves near critical value of nonthermal parameter and arbitrary amplitude solitary waves in presence of nonthermal electrons have also been studied in the paper. Moreover, the solution for ion-acoustic double layers in plasma consisting of nonthermal electrons is obtained. Our results in the paper would be useful to understand the nonlinear wave processes in ionospheric and magnetospheric multicomponent plasma having nonthermal electrons.

  10. Fire Sources of Tropospheric Ozone from the Summer 2008 ARCTAS/ARC-IONS Soundings: Budgets, Trajectory Mapping and IONS-04 and IONS-06 Comparisons

    NASA Astrophysics Data System (ADS)

    Thompson, A. M.; Macfarlane, A.; Tarasick, D. W.; Oltmans, S. J.; Forbes, G.; Miller, S. K.; Klich, C.; Witte, J. C.; Soja, A. J.

    2009-12-01

    Soundings from the ARC-IONS (ARCTAS [Arctic Research of the Composition of the Troposphere with Aircraft and Satellites; http://espo.nasa.gov/arctas] Intensive Ozonesonde Network Study; [http://croc.gsfc.nasa.gov/arcions]) coordinated ozonesonde network have been used to produce (1) five-term tropospheric ozone budgets [based on Laminar ID, as in Luzik, 2009], including fires, using trajectories, fire maps and other tracers; (2) 3-D ozone maps across northern North America using trajectory mapping techniques [Tarasick et al., 2009]. Results will be presented for daily soundings taken over 15 Canadian and US sites in late June and early July 2008, when three NASA aircraft operated for fire-related studies. Besides fire contribution, regional linkages for each site will be illustrated, along with assessment of stratospheric-tropospheric interactions. Ozone budgets from IONS-04 [Tarasick et al., 2007; Thompson et al., 2007] and IONS-06 [Thompson et al., 2008] put ARCTAS in perspective. For several eastern Canadian sites, there were more fire influences in 2008 than in the earlier campaigns, owing to high US fire activity.

  11. New insights into the decay of ion waves to turbulence, ion heating, and soliton generation

    SciTech Connect

    Chapman, T. Banks, J. W.; Berger, R. L.; Cohen, B. I.; Williams, E. A.; Brunner, S.

    2014-04-15

    The decay of a single-frequency, propagating ion acoustic wave (IAW) via two-ion wave decay to a continuum of IAW modes is found to result in a highly turbulent plasma, ion soliton production, and rapid ion heating. Instability growth rates, thresholds, and sensitivities to plasma conditions are studied via fully kinetic Vlasov simulations. The decay rate of IAWs is found to scale linearly with the fundamental IAW potential amplitude ϕ{sub 1} for ZT{sub e}/T{sub i}≲20, beyond which the instability is shown to scale with a higher power of ϕ{sub 1}, where Z is the ion charge number and T{sub e} (T{sub i}) is the electron (ion) thermal temperature. The threshold for instability is found to be smaller by an order of magnitude than linear theory estimates. Achieving a better understanding of the saturation of stimulated Brillouin scatter levels observed in laser-plasma interaction experiments is part of the motivation for this study.

  12. Making Sound Connections

    ERIC Educational Resources Information Center

    Deal, Walter F., III

    2007-01-01

    Sound provides and offers amazing insights into the world. Sound waves may be defined as mechanical energy that moves through air or other medium as a longitudinal wave and consists of pressure fluctuations. Humans and animals alike use sound as a means of communication and a tool for survival. Mammals, such as bats, use ultrasonic sound waves to…

  13. Dispersion relation of electrostatic ion cyclotron waves in multi-component magneto-plasma

    SciTech Connect

    Khaira, Vibhooti Ahirwar, G.

    2015-07-31

    Electrostatic ion cyclotron waves in multi component plasma composed of electrons (denoted by e{sup −}), hydrogen ions (denoted by H{sup +}), helium ions (denoted by He{sup +}) and positively charged oxygen ions (denoted by O{sup +})in magnetized cold plasma. The wave is assumed to propagate perpendicular to the static magnetic field. It is found that the addition of heavy ions in the plasma dispersion modified the lower hybrid mode and also allowed an ion-ion mode. The frequencies of the lower hybrid and ion- ion hybrid modes are derived using cold plasma theory. It is observed that the effect of multi-ionfor different plasma densities on electrostatic ion cyclotron waves is to enhance the wave frequencies. The results are interpreted for the magnetosphere has been applied parameters by auroral acceleration region.

  14. Analysis of propagation characteristics of flexural wave in honeycomb sandwich panel and design of loudspeaker for radiating inclined sound

    NASA Astrophysics Data System (ADS)

    Fujii, Ayaka; Wakatsuki, Naoto; Mizutani, Koichi

    2015-07-01

    A loudspeaker for an auditory guiding system is proposed. This loudspeaker utilizes inclined sound transformed from a flexural wave in a honeycomb sandwich panel. We focused on the fact that the inclined sound propagates extensively with uniform level and direction. Furthermore, sound can be generated without group delay dispersion because the phase velocity of the flexural wave in the sandwich panel becomes constant with increasing frequency. These characteristics can be useful for an auditory guiding system in public spaces since voice-guiding navigation indicates the right direction regardless of position on a pathway. To design the proposed loudspeaker, the behavior of the sandwich panel is predicted using a theoretical equation in which the honeycomb core is assumed as an orthotropic continuum. We calculated the phase velocity dispersion of the flexural wave in the sandwich panel and compared the results obtained using the equation with those of a simulation based on the finite element method and an experiment in order to confirm the applicability of the theoretical equation. It was confirmed that the phase velocities obtained using the theoretical equation and by the simulation were in good agreement with that obtained experimentally. The obtained results suggest that the behavior of the sandwich panel can be predicted using the parameters of the panel. In addition, we designed an optimized honeycomb sandwich panel for radiating inclined sound by calculating the phase velocity characteristics of various panels that have different parameters of core height and cell size using the theoretical equation. Sound radiation from the optimized panel was simulated and compared with that of a homogeneous plate. It was clear that the variance of the radiation angle with varying frequency of the optimized panel was smaller than that of the homogeneous plate. This characteristic of sound radiation with a uniform angle is useful for indicating the destination direction. On

  15. Precipitation of Relativistic Electrons by Electromagnetic Ion Cyclotron (EMIC) Waves

    NASA Astrophysics Data System (ADS)

    Denton, R. E.

    2015-12-01

    We use the electromagnetic ion cyclotron (EMIC) wave fields produced in a two dimensional hybrid code simulation (full dynamics particle ions, but inertialess fluid electrons) in dipole geometry in order to investigate the effect of magnetospheric EMIC waves on relativistic electrons. The plane of the simulation includes variation in the L shell direction and along magnetic field lines. Relativistic test particle electrons are inserted into the simulation when the wave fields are near their maximum amplitude. These electrons can be scattered into the loss cone so that they precipitate into the ionosphere. We find the effective pitch angle diffusion coefficient and probability of precipitation using these test particles. The pitch angle diffusion coefficients are largest for relativistic energies greater than 2 MeV, though they may be substantial for lower energies. The probability of precipitation is highest for low energy particles at small initial equatorial pitch angle. For high initial equatorial pitch angles, the probability of precipitation increases greatly with respect to particle energy. Starting from an isotropic pitch angle distribution of relativistic electrons with a Gaussian spread in the relativistic momentum, we find only a small drop in the probability of precipitation during 13 s time as the particle energy decreases. But that result depends on the initial pitch angle distribution. Starting with a distribution of particles steeply peaked at 90° initial equatorial pitch angle, the probability of precipitation would be greater for high-energy particles. We will discuss the mechanism of pitch angle scattering.

  16. A Schamel equation for ion acoustic waves in superthermal plasmas

    SciTech Connect

    Williams, G. Kourakis, I.; Verheest, F.; Hellberg, M. A.; Anowar, M. G. M.

    2014-09-15

    An investigation of the propagation of ion acoustic waves in nonthermal plasmas in the presence of trapped electrons has been undertaken. This has been motivated by space and laboratory plasma observations of plasmas containing energetic particles, resulting in long-tailed distributions, in combination with trapped particles, whereby some of the plasma particles are confined to a finite region of phase space. An unmagnetized collisionless electron-ion plasma is considered, featuring a non-Maxwellian-trapped electron distribution, which is modelled by a kappa distribution function combined with a Schamel distribution. The effect of particle trapping has been considered, resulting in an expression for the electron density. Reductive perturbation theory has been used to construct a KdV-like Schamel equation, and examine its behaviour. The relevant configurational parameters in our study include the superthermality index κ and the characteristic trapping parameter β. A pulse-shaped family of solutions is proposed, also depending on the weak soliton speed increment u{sub 0}. The main modification due to an increase in particle trapping is an increase in the amplitude of solitary waves, yet leaving their spatial width practically unaffected. With enhanced superthermality, there is a decrease in both amplitude and width of solitary waves, for any given values of the trapping parameter and of the incremental soliton speed. Only positive polarity excitations were observed in our parametric investigation.

  17. Wideband characterization of the complex wave number and characteristic impedance of sound absorbers.

    PubMed

    Salissou, Yacoubou; Panneton, Raymond

    2010-11-01

    Several methods for measuring the complex wave number and the characteristic impedance of sound absorbers have been proposed in the literature. These methods can be classified into single frequency and wideband methods. In this paper, the main existing methods are revisited and discussed. An alternative method which is not well known or discussed in the literature while exhibiting great potential is also discussed. This method is essentially an improvement of the wideband method described by Iwase et al., rewritten so that the setup is more ISO 10534-2 standard-compliant. Glass wool, melamine foam and acoustical/thermal insulator wool are used to compare the main existing wideband non-iterative methods with this alternative method. It is found that, in the middle and high frequency ranges the alternative method yields results that are comparable in accuracy to the classical two-cavity method and the four-microphone transfer-matrix method. However, in the low frequency range, the alternative method appears to be more accurate than the other methods, especially when measuring the complex wave number.

  18. A wave-envelope of sound propagation in nonuniform circular ducts with compressible mean flows

    NASA Technical Reports Server (NTRS)

    Nayfeh, A. H.; Kaiser, J. E.; Shaker, B. S.

    1979-01-01

    An acoustic theory is developed to determine the sound transmission and attenuation through an infinite, hard-walled or lined circular duct carrying compressible, sheared, mean flows and having a variable cross section. The theory is applicable to large as well as small axial variations, as long as the mean flow does not separate. The technique is based on solving for the envelopes of the quasi-parallel acoustic modes that exist in the duct instead of solving for the actual wave, thereby reducing the computation time and the round-off error encountered in purely numerical techniques. The solution recovers the solution based on the method of multiple scales for slowly varying duct geometry. A computer program was developed based on the wave-envelope analysis for general mean flows. Results are presented for the reflection and transmission coefficients as well as the acoustic pressure distributions for a number of conditions: both straight and variable area ducts with and without liners and mean flows from very low to high subsonic speeds are considered.

  19. Travelling-wave ion mobility and negative ion fragmentation of high mannose N-glycans

    PubMed Central

    Harvey, David J.; Scarff, Charlotte A.; Edgeworth, Matthew; Struwe, Weston B.; Pagel, Kevin; Thalassinos, Konstantinos; Crispin, Max; Scrivens, Jim

    2016-01-01

    The isomeric structure of high-mannose N-glycans can significantly impact biological recognition events. Here, the utility of travelling-wave ion mobility-mass spectrometry (TW IM-MS)for isomer separation of high-mannose N-glycans is investigated. Negative ion fragmentation using collision-induced dissociation (CID) gave more informative spectra than positive ion spectra with mass-different fragment ions characterizing many of the isomers. Isomer separation by ion mobility in both ionization modes was generally limited, with the arrival time distributions (ATD) often showing little sign of isomers. However, isomers could be partially resolved by plotting extracted fragment ATDs of the diagnostic fragment ions from the negative ion spectra and the fragmentation spectra of the isomers could be extracted by using ions from limited areas of the ATD peak. In some cases, asymmetric ATDs were observed but no isomers could be detected by fragmentation. In these cases, it was assumed that conformers were being separated. Collision cross sections (CCSs) of the isomers in positive and negative fragmentation mode were estimated from TW IM-MS data using dextran glycans as calibrant. More complete CCS data were achieved in negative ion mode by utilizing the diagnostic fragment ions. Examples of isomer separations are shown for N-glycans released from the well-characterized glycoproteins chicken ovalbumin, porcine thyroglobulin and gp120 from the human immunodeficiency virus. In addition to the cross sectional data, details of the negative ion collision-induced dissociation (CID) spectra of all resolved isomers are discussed. PMID:26956389

  20. Electrostatic ion cyclotron, beam-plasma, and lower hybrid waves excited by an electron beam

    SciTech Connect

    Singh, N.; Conrad, J.R.; Schunk, R.W.

    1985-06-01

    It is pointed out that electrostatic ion cyclotron (EIC) waves have been extensively investigated in connection with both space and laboratory plasmas. The present investigation has the objective to study the excitation of low-frequency waves in a multiion plasma by electron beams. The frequencies considered range from below the lowest gyrofrequency of the heaviest ion to about the lower hybrid frequency. It is shown that electron-beam instabilities can produce peaks in the growth rate below the cyclotron frequency of each ion species if nonzero perpendicular wave number effects are included in the ion dynamics. The dispersion relations for neutralized ion Bernstein (NIB) and pure ion Bernstein (PIB) waves are considered along with an instability analysis for a cold plasma and warm electron beam, the electron beam-plasma mode, banded ion cyclotron (EIC) waves with small perpendicular wavelengths, and the growth lengths of the waves. 39 references.

  1. Electrostatic ion cyclotron, beam-plasma, and lower hybrid waves excited by an electron beam

    NASA Technical Reports Server (NTRS)

    Singh, N.; Conrad, J. R.; Schunk, R. W.

    1985-01-01

    It is pointed out that electrostatic ion cyclotron (EIC) waves have been extensively investigated in connection with both space and laboratory plasmas. The present investigation has the objective to study the excitation of low-frequency waves in a multiion plasma by electron beams. The frequencies considered range from below the lowest gyrofrequency of the heaviest ion to about the lower hybrid frequency. It is shown that electron-beam instabilities can produce peaks in the growth rate below the cyclotron frequency of each ion species if nonzero perpendicular wave number effects are included in the ion dynamics. The dispersion relations for neutralized ion Bernstein (NIB) and pure ion Bernstein (PIB) waves are considered along with an instability analysis for a cold plasma and warm electron beam, the electron beam-plasma mode, banded ion cyclotron (EIC) waves with small perpendicular wavelengths, and the growth lengths of the waves.

  2. Heating of ions to superthermal energies in the topside ionosphere by electrostatic ion cyclotron waves

    NASA Technical Reports Server (NTRS)

    Ungstrup, E.; Klumpar, D. M.; Heikkila, W. J.

    1979-01-01

    The soft particle spectrometer on the Isis 2 spacecraft occasionally observes fluxes of ions moving upward out of the ionosphere in the vicinity of the auroral oval. These ion fluxes are characterized by a sharp pitch angle distribution usually peaked at an angle somewhat greater than 90 deg, indicative of particles heated to a large transverse temperature in a narrow range below the spacecraft. The observations are interpreted in terms of electrostatic ion cyclotron waves, which heat the ions to superthermal energies transverse to the earth's magnetic field. When the transverse energy increases, the repulsive force of the earth's magnetic field, proportional to the particle magnetic moment, repels the particles away from the earth.

  3. Ion reflection by shock waves and pulse generation by cross-field ion beams

    NASA Astrophysics Data System (ADS)

    Ohsawa, Yukiharu

    2017-02-01

    Comparisons are made of two different particle simulations: one for the study of plasma-based accelerators (Gueroult & Fisch, Phys. Plasmas, vol. 23, 2016, 032113) and the other for the study of shock formation in the interstellar medium (Yamauchi & Ohsawa, Phys. Plasmas, vol. 14, 2007, 053110). In the former, shock waves used for plasma density control create ion beams by reflection. In the latter, a fast and dense beam of exploding ions penetrates a surrounding plasma. In both simulations, magnetic bumps are generated from the motion of ion beams perpendicular to a magnetic field. Despite the apparent differences of their purposes, configurations and spatial scales, the two simulations show strong similarities in the generation processes and effects of the bumps, suggesting that these are not rare plasma phenomena. The bump created by the exploding ions develops into backward and forward magnetosonic pulses.

  4. Treatment of Ion-Atom Collisions Using a Partial-Wave Expansion of the Projectile Wavefunction

    ERIC Educational Resources Information Center

    Wong, T. G.; Foster, M.; Colgan, J.; Madison, D. H.

    2009-01-01

    We present calculations of ion-atom collisions using a partial-wave expansion of the projectile wavefunction. Most calculations of ion-atom collisions have typically used classical or plane-wave approximations for the projectile wavefunction, since partial-wave expansions are expected to require prohibitively large numbers of terms to converge…

  5. Plane waves at or near grazing incidence in the parabolic approximation. [acoustic equations of motion for sound fields

    NASA Technical Reports Server (NTRS)

    Mcaninch, G. L.; Myers, M. K.

    1980-01-01

    The parabolic approximation for the acoustic equations of motion is applied to the study of the sound field generated by a plane wave at or near grazing incidence to a finite impedance boundary. It is shown how this approximation accounts for effects neglected in the usual plane wave reflection analysis which, at grazing incidence, erroneously predicts complete cancellation of the incident field by the reflected field. Examples are presented which illustrate that the solution obtained by the parabolic approximation contains several of the physical phenomena known to occur in wave propagation near an absorbing boundary.

  6. Transport induced by ion cyclotron range of frequencies waves

    SciTech Connect

    Zhang, Debing Xu, Yingfeng; Wang, Shaojie

    2014-11-15

    The Vlasov equation, which includes the effect of the ion cyclotron range of frequencies (ICRF) waves, can be written as the Fokker-Planck equation which describes the quasilinear transport in phase space by using the Lie-transform method. The radial transport fluxes of particle, energy and parallel momentum driven by ICRF waves in the slab geometry have been derived. The results show that the ICRF-induced radial redistributions of particle, energy and parallel momentum are driven by the inhomogeneity in energy of the equilibrium distribution function, and related to the correlation between the excursion in the real space and the excursion in energy. For the case with strong asymmetry of k{sub y} spectrum, the ICRF-induced radial transport driven by the energy inhomogeneity dominates the ICRF-induced radial transport driven by the spatial inhomogeneity.

  7. Nonresonant interactions of electromagnetic ion cyclotron waves with relativistic electrons

    NASA Astrophysics Data System (ADS)

    Chen, Lunjin; Thorne, Richard M.; Bortnik, Jacob; Zhang, Xiao-Jia

    2016-10-01

    The dynamics of relativistic electrons traveling through a parallel-propagating, monochromatic electromagnetic ion cyclotron (EMIC) wave in the Earth's dipole field are investigated via test particle simulations. Both resonant and nonresonant responses in electron pitch angle are considered, and the differences between the two are highlighted. Nonresonant electrons, with energies below the minimum resonant energy down to hundreds of keV, are scattered stochastically in pitch angle and can be scattered into the atmospheric loss cone. The nonresonant effect is attributed to the spatial edge associated with EMIC wave packets. A condition for effective nonresonant response is also provided. This effect is excluded from current quasi-linear theory and can be a potentially important loss mechanism of relativistic and subrelativistic electrons in the radiation belts.

  8. Finite-difference theory for sound propagation in a lined duct with uniform flow using the wave envelope concept

    NASA Technical Reports Server (NTRS)

    Baumeister, K. J.

    1977-01-01

    Finite difference equations are derived for sound propagation in a two dimensional, straight, soft wall duct with a uniform flow by using the wave envelope concept. This concept reduces the required number of finite difference grid points by one to two orders of magnitude depending on the length of the duct and the frequency of the sound. The governing acoustic difference equations in complex notation are derived. An exit condition is developed that allows a duct of finite length to simulate the wave propagation in an infinitely long duct. Sample calculations presented for a plane wave incident upon the acoustic liner show the numerical theory to be in good agreement with closed form analytical theory. Complete pressure and velocity printouts are given to some sample problems and can be used to debug and check future computer programs.

  9. Sound generated by instability waves of supersonic flows. I Two-dimensional mixing layers. II - Axisymmetric jets

    NASA Technical Reports Server (NTRS)

    Tam, C. K. W.; Burton, D. E.

    1984-01-01

    An investigation is conducted of the phenomenon of sound generation by spatially growing instability waves in high-speed flows. It is pointed out that this process of noise generation is most effective when the flow is supersonic relative to the ambient speed of sound. The inner and outer asymptotic expansions corresponding to an excited instability wave in a two-dimensional mixing layer and its associated acoustic fields are constructed in terms of the inner and outer spatial variables. In matching the solutions, the intermediate matching principle of Van Dyke and Cole is followed. The validity of the theory is tested by applying it to an axisymmetric supersonic jet and comparing the calculated results with experimental measurements. Very favorable agreements are found both in the calculated instability-wave amplitude distribution (the inner solution) and the near pressure field level contours (the outer solution) in each case.

  10. Ion Bernstein wave heating on the Compact Ignition Tokamak (CIT)

    SciTech Connect

    Ignat, D.W.; Ono, M.

    1989-02-01

    In the present plan, CIT is to be heated by power in the ion cyclotron range of frequencies (ICRF), and electron cyclotron heating (ECH) may be used if suitable rf sources can be developed. We consider the option of ion Bernstein wave heating (IBWH). The key points are that a simple vacuum waveguide launcher can be well- removed from high fluxes of heat and particles and that the development of a suitable source is straightforward. A practical point is that an IBWH waveguide launcher, including transition from coaxial power feeds, fits inside the shield wall surrounding CIT. To confirm IBWH as an option for CIT, experiments are needed on a shaped, H-mode plasma at high power. Successful experiments should be followed by a tube development program to allow CIT heating at 200 - 275 MHz. 2 refs., 3 figs.

  11. Electrostatic ion-cyclotron waves in magnetospheric plasmas Nonlocal aspects

    NASA Technical Reports Server (NTRS)

    Ganguli, G.; Bakshi, P.; Palmadesso, P.

    1984-01-01

    The importance of the effect of the magnetic shear and the finite size of current channel on the electrostatic ion-cyclotron instability for the space plasmas is illustrated. A non-local treatment is used. When the channel width Lc, is larger than the shear length Ls, there is a large reduction in the growth rate along with a noteworthy reduction of the band of the unstable perpendicular wavelengths. For Lc less than or = Ls/10 the growth rate is not much altered from its local value, however for Lc/pi i less than or = 10 to the second power the growth rate starts falling below the local value and vanishes for Lc pi i. The non-local effects lead to enhanced coherence in the ion cyclotron waves. Previously announced in STAR as N84-14917

  12. Ionospheric Ion Upflows Associated with the Alfven Wave Heating

    NASA Astrophysics Data System (ADS)

    Song, P.; Tu, J.

    2014-12-01

    In this study we present the simulation results from a self-consistent inductive-dynamic ionosphere-thermosphere model. In a 2-D numerical simulation (noon-midnight meridian plane), we solve the continuity, momentum, and energy equations for multiple species of ions and neutrals and Maxwell's equations. In particular, the model retains Faraday's law, inertial term in the ion momentum equations and photochemistry. The code is based on an implicit algorithm and simulates a region from 80 km to 5000 km above the Earth. The system is driven by an antisunward motion at the upper boundary of the dayside cusp latitude in both hemispheres. We show that the frictional heating, which can produce upflows of the light (H+ and He+) and heave (O+) ions, is driven by the Alfven wave-induced ion motion relative to the neutrals. The variations of the upflows along a noon-midnight magnetic meridian are examined in association with given driving conditions imposed by the magnetosphere convection.

  13. Modulation instability of ion acoustic waves, solitons, and their interactions in nonthermal electron-positron-ion plasmas

    SciTech Connect

    Zhang Jiefang; Wang Yueyue; Wu Lei

    2009-06-15

    The propagation of ion acoustic waves in plasmas composed of ions, positrons, and nonthermally distributed electrons is investigated. By means of the reduction perturbation technique, a nonlinear Schroedinger equation is derived and the modulation instability of ion acoustic wave is analyzed, where the nonthermal parameter is found to be of significant importance. Furthermore, analytical expressions for the bright and dark solitons are obtained, and the interaction of multiple solitons is discussed.

  14. Modeling of "Stripe" Wave Phenomena Seen by the CHARM II and ACES Sounding Rockets

    NASA Astrophysics Data System (ADS)

    Dombrowski, M. P.; Labelle, J. W.

    2010-12-01

    Two recent sounding-rocket missions—CHARM II and ACES—have been launched from Poker Flat Research Range, carrying the Dartmouth High-Frequency Experiment (HFE) among their primary instruments. The HFE is a receiver system which effectively yields continuous (100% duty cycle) E-field waveform measurements up to 5 MHz. The CHARM II sounding rocket was launched 9:49 UT on 15 February 2010 into a substorm, while the ACES mission consisted of two rockets, launched into quiet aurora at 9:49 and 9:50 UT on 29 January 2009. At approximately 350 km on CHARM II and the ACES High-Flyer, the HFE detected short (~2s) bursts of broadband (200-500 kHz) noise with a 'stripe' pattern of nulls imposed on it. These nulls have 10 to 20 kHz width and spacing, and many show a regular, non-linear frequency-time relation. These events are different from the 'stripes' discussed by Samara and LaBelle [2006] and Colpitts et al. [2010], because of the density of the stripes, the non-linearity, and the appearance of being an absorptive rather than emissive phenomenon. These events are similar to 'stripe' features reported by Brittain et al. [1983] in the VLF range, explained as an interference pattern between a downward-traveling whistler-mode wave and its reflection off the bottom of the ionosphere. Following their analysis method, we modeled our stripes as higher-frequency interfering whistlers reflecting off of a density gradient. This model predicts the near-hyperbolic frequency-time curves and high density of the nulls, and therefore shows promise at explaining the new observations.

  15. Wave field synthesis, adaptive wave field synthesis and ambisonics using decentralized transformed control: Potential applications to sound field reproduction and active noise control

    NASA Astrophysics Data System (ADS)

    Gauthier, Philippe-Aubert; Berry, Alain; Woszczyk, Wieslaw

    2005-09-01

    Sound field reproduction finds applications in listening to prerecorded music or in synthesizing virtual acoustics. The objective is to recreate a sound field in a listening environment. Wave field synthesis (WFS) is a known open-loop technology which assumes that the reproduction environment is anechoic. Classical WFS, therefore, does not perform well in a real reproduction space such as room. Previous work has suggested that it is physically possible to reproduce a progressive wave field in-room situation using active control approaches. In this paper, a formulation of adaptive wave field synthesis (AWFS) introduces practical possibilities for an adaptive sound field reproduction combining WFS and active control (with WFS departure penalization) with a limited number of error sensors. AWFS includes WFS and closed-loop ``Ambisonics'' as limiting cases. This leads to the modification of the multichannel filtered-reference least-mean-square (FXLMS) and the filtered-error LMS (FELMS) adaptive algorithms for AWFS. Decentralization of AWFS for sound field reproduction is introduced on the basis of sources' and sensors' radiation modes. Such decoupling may lead to decentralized control of source strength distributions and may reduce computational burden of the FXLMS and the FELMS algorithms used for AWFS. [Work funded by NSERC, NATEQ, Université de Sherbrooke and VRQ.] Ultrasound/Bioresponse to

  16. Global and seasonal variations in three-dimensional gravity wave momentum flux from satellite limb-sounding temperatures

    NASA Astrophysics Data System (ADS)

    Alexander, M. Joan

    2015-08-01

    Satellite limb-sounding methods provide the best global temperature data available for simultaneous measurement of gravity wave horizontal and vertical structures needed to estimate momentum flux and constrain wave effects on general circulation. Gravity waves vary in the three spatial dimensions and time, so the ideal measurement observes all three dimensions at high resolution nearly simultaneously. High Resolution Dynamics Limb Sounder (HIRDLS) measurements give near-simultaneous profiles in close proximity and at high vertical resolution, but these coincident profiles lie only along the plane of the measurement track. Here we combine HIRDLS and radio occultation data sets to obtain three-dimensional properties of gravity waves on a global scale as well as seasonal variations. The results show dramatic changes from previous estimates using either data set alone. Changes include much larger momentum fluxes and latitudinal variations in propagation direction that support an enhanced role for gravity wave forcing of middle atmosphere circulation.

  17. Heating of ions by high frequency electromagnetic waves in magnetized plasmas

    SciTech Connect

    Zestanakis, P. A.; Kominis, Y.; Hizanidis, K.; Ram, A. K.

    2013-07-15

    The heating of ions by high frequency electrostatic waves in magnetically confined plasmas has been a paradigm for studying nonlinear wave-particle interactions. The frequency of the waves is assumed to be much higher than the ion cyclotron frequency and the waves are taken to propagate across the magnetic field. In fusion type plasmas, electrostatic waves, like the lower hybrid wave, cannot access the core of the plasma. That is a domain for high harmonic fast waves or electron cyclotron waves—these are primarily electromagnetic waves. Previous studies on heating of ions by two or more electrostatic waves are extended to two electromagnetic waves that propagate directly across the confining magnetic field. While the ratio of the frequency of each wave to the ion cyclotron frequency is large, the frequency difference is assumed to be near the ion cyclotron frequency. The nonlinear wave-particle interaction is studied analytically using a two time-scale canonical perturbation theory. The theory elucidates the effects of various parameters on the gain in energy by the ions—parameters such as the amplitudes and polarizations of the waves, the ratio of the wave frequencies to the cyclotron frequency, the difference in the frequency of the two waves, and the wave numbers associated with the waves. For example, the ratio of the phase velocity of the envelope formed by the two waves to the phase velocity of the carrier wave is important for energization of ions. For a positive ratio, the energy range is much larger than for a negative ratio. So waves like the lower hybrid waves will impart very little energy to ions. The theoretical results are found to be in good agreement with numerical simulations of the exact dynamical equations. The analytical results are used to construct mapping equations, simplifying the derivation of the motion of ions, which are, subsequently, used to follow the evolution of an ion distribution function. The heating of ions can then be

  18. Oblique propagation of ion-acoustic solitary waves in a magnetized electron-positron-ion plasma

    SciTech Connect

    Ferdousi, M.; Sultana, S.; Mamun, A. A.

    2015-03-15

    The properties of obliquely propagating ion-acoustic solitary waves in the presence of ambient magnetic field have been investigated theoretically in an electron-positron-ion nonthermal plasma. The plasma nonthermality is introduced via the q-nonextensive distribution of electrons and positrons. The Korteweg-de Vries (K-dV) and modified K-dV (mK-dV) equations are derived by adopting reductive perturbation method. The solution of K-dV and modified K-dV equation, which describes the solitary wave characteristics in the long wavelength limit, is obtained by steady state approach. It is seen that the electron and positron nonextensivity and external magnetic field (obliqueness) have significant effects on the characteristics of solitary waves. A critical value of nonextensivity is found for which solitary structures transit from positive to negative potential. The findings of this investigation may be used in understanding the wave propagation in laboratory and space plasmas where static external magnetic field is present.

  19. Lower hybrid frequency range waves generated by ion polarization drift due to electromagnetic ion cyclotron waves: Analysis of an event observed by the Van Allen Probe B

    NASA Astrophysics Data System (ADS)

    Khazanov, G. V.; Boardsen, S.; Krivorutsky, E. N.; Engebretson, M. J.; Sibeck, D.; Chen, S.; Breneman, A.

    2017-01-01

    We analyze a wave event that occurred near noon between 07:03 and 07:08 UT on 23 February 2014 detected by the Van Allen Probes B spacecraft, where waves in the lower hybrid frequency range (LHFR) and electromagnetic ion cyclotron (EMIC) waves are observed to be highly correlated, with Pearson correlation coefficient of 0.86. We assume that the correlation is the result of LHFR wave generation by the ions' polarization drift in the electric field of the EMIC waves. To check this assumption the drift velocities of electrons and H+, He+, and O+ ions in the measured EMIC wave electric field were modeled. Then the LHFR wave linear instantaneous growth rates for plasma with these changing drift velocities and different plasma compositions were calculated. The time distribution of these growth rates, their frequency distribution, and the frequency dependence of the ratio of the LHFR wave power spectral density (PSD) parallel and perpendicular to the ambient magnetic field to the total PSD were found. These characteristics of the growth rates were compared with the corresponding characteristics of the observed LHFR activity. Reasonable agreement between these features and the strong correlation between EMIC and LHFR energy densities support the assumption that the LHFR wave generation can be caused by the ions' polarization drift in the electric field of an EMIC wave.

  20. Sound Waves Induce Neural Differentiation of Human Bone Marrow-Derived Mesenchymal Stem Cells via Ryanodine Receptor-Induced Calcium Release and Pyk2 Activation.

    PubMed

    Choi, Yura; Park, Jeong-Eun; Jeong, Jong Seob; Park, Jung-Keug; Kim, Jongpil; Jeon, Songhee

    2016-10-01

    Mesenchymal stem cells (MSCs) have shown considerable promise as an adaptable cell source for use in tissue engineering and other therapeutic applications. The aims of this study were to develop methods to test the hypothesis that human MSCs could be differentiated using sound wave stimulation alone and to find the underlying mechanism. Human bone marrow (hBM)-MSCs were stimulated with sound waves (1 kHz, 81 dB) for 7 days and the expression of neural markers were analyzed. Sound waves induced neural differentiation of hBM-MSC at 1 kHz and 81 dB but not at 1 kHz and 100 dB. To determine the signaling pathways involved in the neural differentiation of hBM-MSCs by sound wave stimulation, we examined the Pyk2 and CREB phosphorylation. Sound wave induced an increase in the phosphorylation of Pyk2 and CREB at 45 min and 90 min, respectively, in hBM-MSCs. To find out the upstream activator of Pyk2, we examined the intracellular calcium source that was released by sound wave stimulation. When we used ryanodine as a ryanodine receptor antagonist, sound wave-induced calcium release was suppressed. Moreover, pre-treatment with a Pyk2 inhibitor, PF431396, prevented the phosphorylation of Pyk2 and suppressed sound wave-induced neural differentiation in hBM-MSCs. These results suggest that specific sound wave stimulation could be used as a neural differentiation inducer of hBM-MSCs.

  1. Dust-acoustic solitary waves in dusty plasmas with non-thermal ions

    SciTech Connect

    Asgari, H.; Muniandy, S. V.; Wong, C. S.

    2013-02-15

    Most studies on dusty plasmas have assumed that electrons and ions follow Maxwellian distributions. However, in the presence of energetic ions, the distribution of ions tends to be non-Maxwellian. It is shown here that the existence of non-thermal ions would increase the phase velocity of a dust-acoustic wave. It is also found that the change in the phase velocity profoundly affects the characteristics of a dust-acoustic solitary wave.

  2. An Evaluation of Linear Instability Waves as Sources of Sound in a Supersonic Turbulent Jet

    NASA Technical Reports Server (NTRS)

    Mohseni, Kamran; Colonius, Tim; Freund, Jonathan B.

    2002-01-01

    Mach wave radiation from supersonic jets is revisited to better quantify the extent to which linearized equations represent the details of the actual mechanism. To this end, we solve the linearized Navier-Stokes equations (LNS) with precisely the same mean flow and inflow disturbances as a previous direct numerical simulation (DNS) of a perfectly expanded turbulent M = 1.92 jet. We restrict our attention to the first two azimuthal modes, n = 0 and n = 1, which constitute most of the acoustic field. The direction of peak radiation and the peak Strouhal number matches the DNS reasonably well, which is in accord with previous experimental justification of the linear theory. However, it is found that the sound pressure level predicted by LNS is significantly lower than that from DNS. In order to investigate the discrepancy, individual frequency components of the solution are examined. These confirm that near the peak Strouhal number, particularly for the first helical mode n = 1, the amplification of disturbances in the LNS closely matches the DNS. However, away from the peak frequency (and generally for the azimuthal mode n = 0), modes in the LNS are damped while those in the DNS grow at rates comparable to those at the peak Strouhal number.

  3. Heuristic approximations for sound fields produced by spherical waves incident on locally and non-locally reacting planar surfaces.

    PubMed

    Li, Kai Ming; Tao, Hongdan

    2014-01-01

    The classic Weyl-van der Pol (WVDP) formula is a well-known asymptotic solution for accurately predicting sound fields above a locally reacting ground surface. However, the form of the WVDP formula is inadequate for predicting sound fields in the vicinity of non-locally reacting surfaces; a correction term is often required in the formula to provide accurate numerical solutions. Even with this correction, there is a singularity in the diffraction wave term when the source is located directly above or below the receiver. This paper explores a heuristic method to remove this singularity and suggests an analytical form comparable to the WVDP formula. This improved formula offers a physically interpretable solution and allows for accurate predictions of the total sound field above locally and non-locally reacting surfaces for all geometrical configurations.

  4. Kinetic study of ion acoustic twisted waves with kappa distributed electrons

    NASA Astrophysics Data System (ADS)

    Arshad, Kashif; Aman-ur-Rehman, Mahmood, Shahzad

    2016-05-01

    The kinetic theory of Landau damping of ion acoustic twisted modes is developed in the presence of orbital angular momentum of the helical (twisted) electric field in plasmas with kappa distributed electrons and Maxwellian ions. The perturbed distribution function and helical electric field are considered to be decomposed by Laguerre-Gaussian mode function defined in cylindrical geometry. The Vlasov-Poisson equation is obtained and solved analytically to obtain the weak damping rates of the ion acoustic twisted waves in a non-thermal plasma. The strong damping effects of ion acoustic twisted waves at low values of temperature ratio of electrons and ions are also obtained by using exact numerical method and illustrated graphically, where the weak damping wave theory fails to explain the phenomenon properly. The obtained results of Landau damping rates of the twisted ion acoustic wave are discussed at different values of azimuthal wave number and non-thermal parameter kappa for electrons.

  5. Ducted electromagnetic waves in the Martian ionosphere detected by the Mars Advanced Radar for Subsurface and Ionosphere Sounding radar

    NASA Astrophysics Data System (ADS)

    Zhang, Zhenfei; Orosei, Roberto; Huang, Qian; Zhang, Jie

    2016-07-01

    In the data of the Mars Advanced Radar for Subsurface and Ionosphere Sounding on board the European Space Agency (ESA) mission Mars Express (MEX), a distinctive type of signals (called the "epsilon signature"), which is similar to that previously detected during radio sounding of the terrestrial F region ionosphere, is found. The signature is interpreted to originate from multiple reflections of electromagnetic waves propagating along sounder pulse-created, crustal magnetic field-aligned plasma bubbles (waveguides). The signatures have a low (below 0.5%) occurrence rate and apparent cutoff frequencies 3-5 times higher than the theoretical one for an ordinary mode wave. These properties are explained by the influence of the perpendicular ionospheric plasma density gradient and the sounder pulse frequency on the formation of waveguides.

  6. Prediction of Sound Waves Propagating Through a Nozzle Without/With a Shock Wave Using the Space-Time CE/SE Method

    NASA Technical Reports Server (NTRS)

    Wang, Xiao-Yen; Chang, Sin-Chung; Jorgenson, Philip C. E.

    2000-01-01

    The benchmark problems in Category 1 (Internal Propagation) of the third Computational Aeroacoustics (CAA) Work-shop sponsored by NASA Glenn Research Center are solved using the space-time conservation element and solution element (CE/SE) method. The first problem addresses the propagation of sound waves through a nearly choked transonic nozzle. The second one concerns shock-sound interaction in a supersonic nozzle. A quasi one-dimension CE/SE Euler solver for a nonuniform mesh is developed and employed to solve both problems. Numerical solutions are compared with the analytical solution for both problems. It is demonstrated that the CE/SE method is capable of solving aeroacoustic problems with/without shock waves in a simple way. Furthermore, the simple nonreflecting boundary condition used in the CE/SE method which is not based on the characteristic theory works very well.

  7. Localization of ultra-low frequency waves in multi-ion plasmas of the planetary magnetosphere

    SciTech Connect

    Kim, Eun -Hwa; Johnson, Jay R.; Lee, Dong -Hun

    2015-01-01

    By adopting a 2D time-dependent wave code, we investigate how mode-converted waves at the Ion-Ion Hybrid (IIH) resonance and compressional waves propagate in 2D density structures with a wide range of field-aligned wavenumbers to background magnetic fields. The simulation results show that the mode-converted waves have continuous bands across the field line consistent with previous numerical studies. These waves also have harmonic structures in frequency domain and are localized in the field-aligned heavy ion density well. Lastly, our results thus emphasize the importance of a field-aligned heavy ion density structure for ultra-low frequency wave propagation, and suggest that IIH waves can be localized in different locations along the field line.

  8. Time-fractional Gardner equation for ion-acoustic waves in negative-ion-beam plasma with negative ions and nonthermal nonextensive electrons

    NASA Astrophysics Data System (ADS)

    Guo, Shimin; Mei, Liquan; Zhang, Zhengqiang

    2015-05-01

    Nonlinear propagation of ion-acoustic waves is investigated in a one-dimensional, unmagnetized plasma consisting of positive ions, negative ions, and nonthermal electrons featuring Tsallis distribution that is penetrated by a negative-ion-beam. The classical Gardner equation is derived to describe nonlinear behavior of ion-acoustic waves in the considered plasma system via reductive perturbation technique. We convert the classical Gardner equation into the time-fractional Gardner equation by Agrawal's method, where the time-fractional term is under the sense of Riesz fractional derivative. Employing variational iteration method, we construct solitary wave solutions of the time-fractional Gardner equation with initial condition which depends on the nonlinear and dispersion coefficients. The effect of the plasma parameters on the compressive and rarefactive ion-acoustic solitary waves is also discussed in detail.

  9. Time-fractional Gardner equation for ion-acoustic waves in negative-ion-beam plasma with negative ions and nonthermal nonextensive electrons

    SciTech Connect

    Guo, Shimin Mei, Liquan; Zhang, Zhengqiang

    2015-05-15

    Nonlinear propagation of ion-acoustic waves is investigated in a one-dimensional, unmagnetized plasma consisting of positive ions, negative ions, and nonthermal electrons featuring Tsallis distribution that is penetrated by a negative-ion-beam. The classical Gardner equation is derived to describe nonlinear behavior of ion-acoustic waves in the considered plasma system via reductive perturbation technique. We convert the classical Gardner equation into the time-fractional Gardner equation by Agrawal's method, where the time-fractional term is under the sense of Riesz fractional derivative. Employing variational iteration method, we construct solitary wave solutions of the time-fractional Gardner equation with initial condition which depends on the nonlinear and dispersion coefficients. The effect of the plasma parameters on the compressive and rarefactive ion-acoustic solitary waves is also discussed in detail.

  10. A Statistical Analysis of Langmuir Wave-Electron Correlations Observed by the CHARM II Auroral Sounding Rocket

    NASA Astrophysics Data System (ADS)

    Dombrowski, M. P.; Labelle, J. W.; Kletzing, C.; Bounds, S. R.; Kaeppler, S. R.

    2014-12-01

    Langmuir-mode electron plasma waves are frequently observed by spacecraft in active plasma environments such as the ionosphere. Ionospheric Langmuir waves may be excited by the bump-on-tail instability generated by impinging beams of electrons traveling parallel to the background magnetic field (B). The Correlation of High-frequencies and Auroral Roar Measurement (CHARM II) sounding rocket was launched into a substorm at 9:49 UT on 17 February 2010, from the Poker Flat Research Range in Alaska. The primary instruments included the University of Iowa Wave-Particle Correlator (WPC), the Dartmouth High-Frequency Experiment (HFE), several charged particle detectors, low-frequency wave instruments, and a magnetometer. The HFE is a receiver system which effectively yields continuous (100% duty cycle) electric-field waveform measurements from 100 kHz to 5 MHz, and which had its detection axis aligned nominally parallel to B. The HFE output was fed on-payload to the WPC, which uses a phase-locked loop to track the incoming wave frequency with the most power, then sorting incoming electrons at eight energy levels into sixteen wave-phase bins. CHARM II encountered several regions of strong Langmuir wave activity throughout its 15-minute flight, and the WPC showed wave-lock and statistically significant particle correlation distributions during several time periods. We show results of an in-depth analysis of the CHARM II WPC data for the entire flight, including statistical analysis of correlations which show evidence of direct interaction with the Langmuir waves, indicating (at various times) trapping of particles and both driving and damping of Langmuir waves by particles. In particular, the sign of the gradient in particle flux appears to correlate with the phase relation between the electrons and the wave field, with possible implications for the wave physics.

  11. Effect of a progressive sound wave on the profiles of spectral lines. 2: Asymmetry of faint Fraunhofer lines. [absorption spectra

    NASA Technical Reports Server (NTRS)

    Kostyk, R. I.

    1974-01-01

    The absorption coefficient profile was calculated for lines of different chemical elements in a medium with progressive sound waves. Calculations show that (1) the degree and direction of asymmetry depend on the atomic ionization potential and the potential of lower level excitation of the individual line; (2) the degree of asymmetry of a line decreases from the center toward the limb of the solar disc; and (3) turbulent motions 'suppress' the asymmetry.

  12. Application of Local Time Dependent Ion Composition to Observations, Modeling, and Effects of Electromagnetic Ion Cyclotron Waves

    NASA Astrophysics Data System (ADS)

    Lee, J. H.; Angelopoulos, V.; Chen, L.; Thorne, R. M.

    2014-12-01

    Numerous global magnetospheric studies on electromagnetic ion cyclotron (EMIC) waves have revealed the typical wave properties observed throughout the Earth's magnetosphere. The observed trends in the wave properties at various geocentric distances and local time sectors, although in general agreement, elude satisfactory explanation without further details on the ambient plasma properties, the low-energy (few to ~100 eV) ions in particular. Recent studies also described techniques to deduce the presence and properties of low-energy ions and the application of such a technique to THEMIS (Time History of Events and Macroscale Interactions during Substorms) data has revealed the typical low-energy ion compositional properties throughout the Earth's magnetosphere. Motivated by the recent work on EMIC waves and low-energy ion composition, we analyze typical wave cases observed at each local time sector by the THEMIS satellites and apply the composition techniques or the statistical low-energy ion composition data to constrain the low-energy components in modeling of each wave case in the context of linear hot plasma theory. We find that the observed waves are modeled well with hot plasma theory and both are fully consistent with the composition of the ambient plasma. Our results suggest that combined ion composition and wave measurements are critical for further assessment of the effects of the waves on energetic particles. In the cases we report on here, we find the waves could resonantly interact with electrons at energies in excess of 2 MeV and therefore do not have an effect on the dominant trapped electron population.

  13. Interference pattern of the sound field in the presence of an internal Kelvin wave in a stratified lake.

    PubMed

    Katsnelson, Boris; Lunkov, Andrey; Ostrovsky, Ilia

    2016-02-01

    Internal Kelvin waves (IKWs) initiated by rotation of the Earth are one of the main hydrodynamic phenomena in large stratified lakes where baroclinic Rossby radius of deformation is smaller than the horizontal scale of the lake. IKWs can be identified using the spectra of internal waves, where in the presence of IKWs, the inertial frequency is at maximum. IKWs play a rather important role in the lake's dynamics for different processes, both in the water layer and sediment, especially at the periphery of lake. Due to influence of internal waves on the sound propagation, acoustical methods can be used for estimation of behaviour of IKWs. In this paper, the spatiotemporal variability of the mid-frequency (∼1 kHz) sound field in the presence of IKWs in a deep stratified Lake Kinneret is studied using numerical simulations based on normal-mode theory. Due to the specific character of perturbation of the water layer, IKWs can cause specific variations of interference pattern, in particular, a significant shift of the sound interference pattern both in spatial and frequency domain. These shifts can be easily measured and used for reconstruction of IKW parameters.

  14. A Simple Experiment to Explore Standing Waves in a Flexible Corrugated Sound Tube

    NASA Astrophysics Data System (ADS)

    Amorim, Maria Eva; Sousa, Teresa Delmira; Carvalho, P. Simeão; Sousa, Adriano Sampaioe

    2011-09-01

    Sound tubes, pipes, and singing rods are used as musical instruments and as toys to perform amusing experiments. In particular, corrugated tubes present unique characteristics with respect to the sounds they can produce; that is why they have been studied so intensively, both at theoretical and experimental levels.1-4 Experimental studies usually involve expensive and sophisticated equipment that is out of reach of school laboratory facilities.3-6 In this paper we show how to investigate quantitatively the sounds produced by a flexible sound tube corrugated on the inside by using educational equipment readily available in school laboratories, such as the oscilloscope, the microphone, the anemometer, and the air pump. We show that it is possible for students to study the discontinuous spectrum of sounds produced by a flexible corrugated tube and go even further, computing the speed of sound in air with a simple experimental procedure.

  15. Van Allen Probes observations of cross-scale coupling between electromagnetic ion cyclotron waves and higher-frequency wave modes

    NASA Astrophysics Data System (ADS)

    Colpitts, C. A.; Cattell, C. A.; Engebretson, M.; Broughton, M.; Tian, S.; Wygant, J.; Breneman, A.; Thaller, S.

    2016-11-01

    We present observations of higher-frequency ( 50-2500 Hz, 0.1-0.7 fce) wave modes modulated at the frequency of colocated lower frequency (0.5-2 Hz, on the order of fci) waves. These observations come from the Van Allen Probes Electric Field and Waves instrument's burst mode data and represent the first observations of coupling between waves in these frequency ranges. The higher-frequency wave modes, typically whistler mode hiss and chorus or magnetosonic waves, last for a few to a few tens of seconds but are in some cases observed repeatedly over several hours. The higher-frequency waves are observed to be unmodulated before and after the presence of the electromagnetic ion cyclotron (EMIC) waves, but when the EMIC waves are present, the amplitude of the higher-frequency waves drops to the instrument noise level once every EMIC wave cycle. Such modulation could significantly impact wave-particle interactions such as acceleration and pitch angle scattering, which are crucial in the formation and depletion of the radiation belts. We present one case study with broadband, high-frequency waves observed to be modulated by EMIC waves repeatedly over a 2 h time span on both spacecraft. Finally, we show two additional case studies where other high-frequency wave modes exhibit similar modulation.

  16. Anomerization of Acrylated Glucose During Traveling Wave Ion Mobility Spectrometry

    NASA Astrophysics Data System (ADS)

    Chendo, Christophe; Moreira, Guillaume; Tintaru, Aura; Posocco, Paola; Laurini, Erik; Lefay, Catherine; Gigmes, Didier; Viel, Stéphane; Pricl, Sabrina; Charles, Laurence

    2015-09-01

    Anomerization of simple sugars in the liquid phase is known as an acid- and base-catalyzed process, which highly depends on solvent polarity. This reaction is reported here to occur in the gas phase, during traveling wave ion mobility spectrometry (TWIMS) experiments aimed at separating α- and β-anomers of penta-acrylated glucose generated as ammonium adducts in electrospray ionization. This compound was available in two samples prepared from glucose dissolved in solvents of different polarity, namely tetrahydrofuran (THF) and N,N-dimethylacetamide (DMAC), and analyzed by electrospray tandem mass spectrometry (ESI-MS/MS) as well as traveling wave ion mobility (ESI-TWIMS-MS). In MS/MS, an anchimerically-assisted process was found to be unique to the electrosprayed α-anomer, and was only observed for the THF sample. In ESI-TWIMS-MS, a signal was measured at the drift time expected for the α-anomer for both the THF and DMAC samples, in apparent contradiction to the MS/MS results, which indicated that the α-anomer was not present in the DMAC sample. However, MS/MS experiments performed after TWIMS separation revealed that ammonium adducts of the α-anomer produced from each sample, although exhibiting the same collision cross section, were clearly different. Indeed, while the α-anomer actually present in the THF sample was electrosprayed with the ammonium adducted at the C2 acrylate, its homologue only observed when the DMAC sample was subjected to TWIMS hold the adducted ammonium at the C1 acrylate. These findings were explained by a β/α inter-conversion upon injection in the TWIMS cell, as supported by theoretical calculation and dynamic molecular modeling.

  17. Modified ion-acoustic solitary waves in plasmas with field-aligned shear flows

    SciTech Connect

    Saleem, H.; Haque, Q.

    2015-08-15

    The nonlinear dynamics of ion-acoustic waves is investigated in a plasma having field-aligned shear flow. A Korteweg-deVries-type nonlinear equation for a modified ion-acoustic wave is obtained which admits a single pulse soliton solution. The theoretical result has been applied to solar wind plasma at 1 AU for illustration.

  18. Ion-acoustic rogue waves in magnetized solar wind plasma with nonextensive electrons

    NASA Astrophysics Data System (ADS)

    Bacha, Mustapha; Gougam, Leila Ait; Tribeche, Mouloud

    2017-01-01

    Ion-acoustic rogue waves are investigated in a two-component magnetized solar wind plasma, composed of positively charged fluid ions, as well as nonextensive electrons. Typical solar wind plasmas parameters are used. It is shown that the wave number domain for the onset of ion-acoustic modulational instability enlarges as the electrons evolve towards their thermal equilibrium. Interestingly, we show that as the solar wind plasma expands far out from the sun, the wave amplitude increases and the IA rogue wave concentrates therefore a significant amount of energy. Our investigation may be of wide relevance to astronomers and space scientists working on the solar wind and interstellar plasmas.

  19. Dynamic behavior of ion acoustic waves in electron-positron-ion magnetoplasmas with superthermal electrons and positrons

    SciTech Connect

    Saha, Asit E-mail: prasantachatterjee1@rediffmail.com; Pal, Nikhil; Chatterjee, Prasanta E-mail: prasantachatterjee1@rediffmail.com

    2014-10-15

    The dynamic behavior of ion acoustic waves in electron-positron-ion magnetoplasmas with superthermal electrons and positrons has been investigated in the framework of perturbed and non-perturbed Kadomtsev-Petviashili (KP) equations. Applying the reductive perturbation technique, we have derived the KP equation in electron-positron-ion magnetoplasma with kappa distributed electrons and positrons. Bifurcations of ion acoustic traveling waves of the KP equation are presented. Using the bifurcation theory of planar dynamical systems, the existence of the solitary wave solutions and the periodic traveling wave solutions has been established. Two exact solutions of these waves have been derived depending on the system parameters. Then, using the Hirota's direct method, we have obtained two-soliton and three-soliton solutions of the KP equation. The effect of the spectral index κ on propagations of the two-soliton and the three-soliton has been shown. Considering an external periodic perturbation, we have presented the quasi periodic behavior of ion acoustic waves in electron-positron-ion magnetoplasmas.

  20. Low dust charging rate induced weakly dissipative dust acoustic solitary waves: Role of nonthermal ions

    SciTech Connect

    Chaudhuri, Tushar Kanti; Khan, Manoranjan; Gupta, M. R.; Ghosh, Samiran

    2007-10-15

    The effects of low dust charging rate compared to the dust oscillation frequency and nonthermal ions on small but finite amplitude nonlinear dust acoustic wave have been investigated. It is seen that because of the low dust charging rate, the nonlinear wave exhibits weakly dissipative solitary wave that is governed by a modified form of the Korteweg-de Vries equation. The solitary wave possesses both rarefactive and compressive soliton solution depending on the values of ion nonthermality parameter a. An analytical solution reveals that because of the simultaneous effects of low dust charging rate and nonthermal ions, the wave amplitude may grow exponentially with time if the ion nonthermality parameter (a) exceeds a critical value provided the ion-electron temperature ratio ({sigma}{sub i}) is less than 0.11.

  1. On dust ion acoustic solitary waves in collisional dusty plasmas with ionization effect

    NASA Astrophysics Data System (ADS)

    Shalaby, M.; El-Labany, S. K.; El-Shamy, E. F.; Khaled, M. A.

    2010-04-01

    The propagation of solitary waves in an unmagnetized collisional dusty plasma consisting of a negatively charged dust fluid, positively charged ions, isothermal electrons, and background neutral particles is studied. The ionization, ion loss, ion-neutral, ion-dust, and dust-neutral collisions are considered. Applying a reductive perturbation theory, a damped Korteweg-de Vries (DKdV) equation is derived. On the other hand, at a critical phase velocity, the dynamics of solitary waves is governed by a damped modified Korteweg-de Vries (DMKdV) equation. The nonlinear properties of solitary waves in the two cases are discussed.

  2. Numerical Simulation of Waves Driven by Plasma Currents Generated by Low-Frequency Alfven Waves in a Multi-Ion Plasma

    NASA Technical Reports Server (NTRS)

    Singh, Nagendra; Khazanov, George

    2004-01-01

    When multi-ion plasma consisting of heavy and light ions is permeated by a low-frequency Alfven (LFA) wave, the crossed-electric-and-magnetic field (E x B), and the polarization drifts of the different ion species and the electrons could be quite different. The relative drifts between the charged-particle species drive waves, which energize the plasma. Using 2.5-dimensional (2.5-D) particle-in-cell simulations, we study this process of wave generation and its nonlinear consequences in terms of acceleration and heating plasma. Specifically, we study the situation for LFA wave frequency being lower than the heavy-ion cyclotron frequency in a multi-ion plasma. We impose such a wave to the plasma assuming that its wavelength is much larger than that of the waves generated by the relative drifts. For better understanding, the LFA-wave driven simulations are augmented by those driven by initialized ion beams. The driven high-frequency (HF) wave modes critically depend on the heavy ion density nh; for small values of nh, the lower hybrid (LH) waves dominate. On the other hand, for large nh a significantly enhanced level of waves occurs over a much broader frequency spectrum below the LH frequency and such waves are interpreted here as the ion Bernstein (IB) mode near the light ion cyclotron harmonics. Irrespective of the driven wave modes, both the light and heavy ions undergo significant transverse acceleration, but for the large heavy-ion densities, even the electrons are significantly accelerated in the parallel direction by the waves below the LH frequency. Even when the LFA wave drive is maintained, the ion heating leads to the cessation of HF wave excitation just after a few cycles of the former wave. On the basis of marginal stability seen in the simulations, an empirical relation for LFA wave amplitude, frequency and ion temperature is given.

  3. Localization of ultra-low frequency waves in multi-ion plasmas of the planetary magnetosphere

    DOE PAGES

    Kim, Eun -Hwa; Johnson, Jay R.; Lee, Dong -Hun

    2015-01-01

    By adopting a 2D time-dependent wave code, we investigate how mode-converted waves at the Ion-Ion Hybrid (IIH) resonance and compressional waves propagate in 2D density structures with a wide range of field-aligned wavenumbers to background magnetic fields. The simulation results show that the mode-converted waves have continuous bands across the field line consistent with previous numerical studies. These waves also have harmonic structures in frequency domain and are localized in the field-aligned heavy ion density well. Lastly, our results thus emphasize the importance of a field-aligned heavy ion density structure for ultra-low frequency wave propagation, and suggest that IIH wavesmore » can be localized in different locations along the field line.« less

  4. Horizontal coherence of low-frequency fixed-path sound in a continental shelf region with internal-wave activity.

    PubMed

    Duda, Timothy F; Collis, Jon M; Lin, Ying-Tsong; Newhall, Arthur E; Lynch, James F; DeFerrari, Harry A

    2012-02-01

    Sound at 85 to 450 Hz propagating in approximately 80-m depth water from fixed sources to a joint horizontal/vertical line array (HLA/VLA) is analyzed. The data are from a continental shelf area east of Delaware Bay (USA) populated with tidally generated long- and short-wavelength internal waves. Sound paths are 19 km in the along-shore (along internal-wave crest) direction and 30 km in the cross-shore direction. Spatial statistics of HLA arrivals are computed as functions of beam steering angle and time. These include array gain, horizontally lagged spatial correlation function, and coherent beam power. These quantities vary widely in magnitude, and vary over a broad range of time scales. For example, correlation scale can change rapidly from forty to five wavelengths, and correlation-scale behavior is anisotropic. In addition, the vertical array can be used to predict correlation expected for adiabatic propagation with cylindrical symmetry, forming a benchmark. Observed variations are in concert with internal-wave activity. Temporal variations of three coherence measures, horizontal correlation length, array gain, and ratio of actual correlation length to predicted adiabatic-mode correlation length, are very strong, varying by almost a factor of ten as internal waves pass.

  5. A Simple Experiment to Explore Standing Waves in a Flexible Corrugated Sound Tube

    ERIC Educational Resources Information Center

    Amorim, Maria Eva; Sousa, Teresa Delmira; Carvalho, P. Simeao; Sousa, Adriano Sampaioe

    2011-01-01

    Sound tubes, pipes, and singing rods are used as musical instruments and as toys to perform amusing experiments. In particular, corrugated tubes present unique characteristics with respect to the sounds they can produce; that is why they have been studied so intensively, both at theoretical and experimental levels. Experimental studies usually…

  6. Bifurcations of dust ion acoustic travelling waves in a magnetized quantum dusty plasma

    NASA Astrophysics Data System (ADS)

    Samanta, Utpal Kumar; Saha, Asit; Chatterjee, Prasanta

    2013-10-01

    Bifurcation behavior of nonlinear dust ion acoustic travelling waves in a magnetized quantum dusty plasma has been studied. Applying the reductive perturbation technique (RPT), we have derived a Kadomtsev-Petviashili (KP) equation for dust ion acoustic waves (DIAWs) in a magnetized quantum dusty plasma. By using the bifurcation theory of planar dynamical systems to the KP equation, we have proved that our model has solitary wave solutions and periodic travelling wave solutions. We have derived two exact explicit solutions of the above travelling waves depending on different parameters.

  7. Effect of a RF Wave on Ion Cyclotron Instability in Size Distributed Impurities Containing Plasmas

    SciTech Connect

    Sharma, A. K.; Tripathi, V. K.; Annou, R.

    2008-09-07

    The effect of a large amplitude lower hybrid wave on current driven ion cyclotron waves in a dusty plasma where dust grains are size distributed is examined. The influence of the lower hybrid wave on the stabilization of the instability is studied. The efficacy of rf is dust density dependent.

  8. Apparatus for studying wave motion and sound at the University of Nebraska-Lincoln's ``Historical Scientific Instrument Gallery.''

    NASA Astrophysics Data System (ADS)

    Wang, Lily M.; Rudd, M. Eugene

    2004-05-01

    The University of Nebraska-Lincoln's ``Historical Scientific Instrument Gallery,'' compiled by the second author in 1998, contains approximately 700 inventoried items and may be visited on-line at http://physics.unl.edu/outreach/histinstr/. Amidst the collection are several acoustical instruments that were used in the early 1900s. These include equipment that demonstrate wave motion (traveling wave machine, mercury ripple dish, vibration microscope), wave interference (interference machine), resonance conditions (Helmholtz resonators, vibrating rods, singing flames, sonometer), and sound generation (Galton's whistles, high-frequency tuning forks, large tuning forks, organ pipes, siren saw). A review of the equipment and the history of their use at the University of Nebraska are discussed. Much of the equipment was superbly manufactured by the Max Kohl/Chemnitz Company in Germany and Rudolph Koenig in France. Pages from the Max Kohl/Chemnitz equipment catalogs of 1910 and 1925 helped to characterize several of the pieces and are shown in this presentation.

  9. A passive low frequency instrument for radio wave sounding the subsurface oceans of the Jovian icy moons: An instrument concept

    NASA Astrophysics Data System (ADS)

    Hartogh, P.; Ilyushin, Ya. A.

    2016-10-01

    Exploration of subsurface oceans on Jovian icy moons is a key issue of the icy moons' geology. Electromagnetic wave propagation is the only way to probe their icy mantles from the orbit. In the present paper, a principal concept of a passive interferometric instrument for deep sounding of the icy moons' crust is proposed. Its working principle is measuring and correlating Jupiter's radio wave emissions with reflections from the deep sub-surface of the icy moons. A number of the functional aspects of the proposed experiment are studied, in particular, impact of the wave scattering on the surface terrain on the instrument performance and digital sampling of the noisy signal. Results of the test of the laboratory prototype of the instrument are also presented in the paper.

  10. Nonlinear ion-acoustic cnoidal waves in a dense relativistic degenerate magnetoplasma.

    PubMed

    El-Shamy, E F

    2015-03-01

    The complex pattern and propagation characteristics of nonlinear periodic ion-acoustic waves, namely, ion-acoustic cnoidal waves, in a dense relativistic degenerate magnetoplasma consisting of relativistic degenerate electrons and nondegenerate cold ions are investigated. By means of the reductive perturbation method and appropriate boundary conditions for nonlinear periodic waves, a nonlinear modified Korteweg-de Vries (KdV) equation is derived and its cnoidal wave is analyzed. The various solutions of nonlinear ion-acoustic cnoidal and solitary waves are presented numerically with the Sagdeev potential approach. The analytical solution and numerical simulation of nonlinear ion-acoustic cnoidal waves of the nonlinear modified KdV equation are studied. Clearly, it is found that the features (amplitude and width) of nonlinear ion-acoustic cnoidal waves are proportional to plasma number density, ion cyclotron frequency, and direction cosines. The numerical results are applied to high density astrophysical situations, such as in superdense white dwarfs. This research will be helpful in understanding the properties of compact astrophysical objects containing cold ions with relativistic degenerate electrons.

  11. Nonlinear ion-acoustic cnoidal waves in a dense relativistic degenerate magnetoplasma

    NASA Astrophysics Data System (ADS)

    El-Shamy, E. F.

    2015-03-01

    The complex pattern and propagation characteristics of nonlinear periodic ion-acoustic waves, namely, ion-acoustic cnoidal waves, in a dense relativistic degenerate magnetoplasma consisting of relativistic degenerate electrons and nondegenerate cold ions are investigated. By means of the reductive perturbation method and appropriate boundary conditions for nonlinear periodic waves, a nonlinear modified Korteweg-de Vries (KdV) equation is derived and its cnoidal wave is analyzed. The various solutions of nonlinear ion-acoustic cnoidal and solitary waves are presented numerically with the Sagdeev potential approach. The analytical solution and numerical simulation of nonlinear ion-acoustic cnoidal waves of the nonlinear modified KdV equation are studied. Clearly, it is found that the features (amplitude and width) of nonlinear ion-acoustic cnoidal waves are proportional to plasma number density, ion cyclotron frequency, and direction cosines. The numerical results are applied to high density astrophysical situations, such as in superdense white dwarfs. This research will be helpful in understanding the properties of compact astrophysical objects containing cold ions with relativistic degenerate electrons.

  12. PICKUP ION MEDIATED PLASMAS. I. BASIC MODEL AND LINEAR WAVES IN THE SOLAR WIND AND LOCAL INTERSTELLAR MEDIUM

    SciTech Connect

    Zank, G. P.; Hunana, P.; Mostafavi, P.; Goldstein, M. L.

    2014-12-20

    Pickup ions (PUIs) in the outer heliosphere and the local interstellar medium are created by charge exchange between protons and hydrogen (H) atoms, forming a thermodynamically dominant component. In the supersonic solar wind beyond >10 AU, in the inner heliosheath (IHS), and in the very local interstellar medium (VLISM), PUIs do not equilibrate collisionally with the background plasma. Using a collisionless form of Chapman-Enskog expansion, we derive a closed system of multi-fluid equations for a plasma comprised of thermal protons and electrons, and suprathermal PUIs. The PUIs contribute an isotropic scalar pressure to leading order, a collisionless heat flux at the next order, and a collisionless stress tensor at the second-order. The collisionless heat conduction and viscosity in the multi-fluid description results from a non-isotropic PUI distribution. A simpler one-fluid MHD-like system of equations with distinct equations of state for both the background plasma and the PUIs is derived. We investigate linear wave properties in a PUI-mediated three-fluid plasma model for parameters appropriate to the VLISM, the IHS, and the solar wind in the outer heliosphere. Five distinct wave modes are possible: Alfvén waves, thermal fast and slow magnetoacoustic waves, PUI fast and slow magnetoacoustic waves, and an entropy mode. The thermal and PUI acoustic modes propagate at approximately the combined thermal magnetoacoustic speed and the PUI sound speed respectively. All wave modes experience damping by the PUIs through the collisionless PUI heat flux. The PUI-mediated plasma model yields wave properties, including Alfvén waves, distinctly different from those of the standard two-fluid model.

  13. Flute mode waves near the lower hybrid frequency excited by ion rings in velocity space

    NASA Technical Reports Server (NTRS)

    Cattell, C.; Hudson, M.

    1982-01-01

    Discrete emissions at the lower hybrid frequency are often seen on the S3-3 satellite. Simultaneous observation of perpendicularly heated ions suggests that these ions may provide the free energy necessary to drive the instability. Studies of the dispersion relation for flute modes excited by warm ion rings in velocity space show that waves are excited with real frequencies near the lower hybrid frequency and with growth rates ranging from about 0.01 to 1 times the ion cyclotron frequency. Numerical results are therefore consistent with the possibility that the observed ions are the free energy source for the observed waves.

  14. ENERGY CONSERVATION AND GRAVITY WAVES IN SOUND-PROOF TREATMENTS OF STELLAR INTERIORS. PART I. ANELASTIC APPROXIMATIONS

    SciTech Connect

    Brown, Benjamin P.; Zweibel, Ellen G.; Vasil, Geoffrey M.

    2012-09-10

    Typical flows in stellar interiors are much slower than the speed of sound. To follow the slow evolution of subsonic motions, various sound-proof equations are in wide use, particularly in stellar astrophysical fluid dynamics. These low-Mach number equations include the anelastic equations. Generally, these equations are valid in nearly adiabatically stratified regions like stellar convection zones, but may not be valid in the sub-adiabatic, stably stratified stellar radiative interiors. Understanding the coupling between the convection zone and the radiative interior is a problem of crucial interest and may have strong implications for solar and stellar dynamo theories as the interface between the two, called the tachocline in the Sun, plays a crucial role in many solar dynamo theories. Here, we study the properties of gravity waves in stably stratified atmospheres. In particular, we explore how gravity waves are handled in various sound-proof equations. We find that some anelastic treatments fail to conserve energy in stably stratified atmospheres, instead conserving pseudo-energies that depend on the stratification, and we demonstrate this numerically. One anelastic equation set does conserve energy in all atmospheres and we provide recommendations for converting low-Mach number anelastic codes to this set of equations.

  15. Dispersion characteristics of the electromagnetic waves in a relativistic electron beam guided by the ion channel

    SciTech Connect

    Mirzanejhad, Saeed; Sohbatzadeh, Farshad; Ghasemi, Maede; Sedaghat, Zeinab; Mahdian, Zeinab

    2010-05-15

    In this article, the dispersion characteristics of the paraxial (near axis) electromagnetic (EM) waves in a relativistic electron beam guided by the ion channel are investigated. Equilibrium fields such as ion-channel electrostatic field and self-fields of relativistic electron beam are included in this formalism. In accordance with the equilibrium field structure, radial and azimuthal waves are selected as base vectors for EM waves. It is shown that the dispersion of the radially polarized EM and space charge waves are influenced by the equilibrium fields, but azimuthally polarized wave remain unaffected. In some wave number domains, the radially polarized EM and fast space charge waves are coupled. In these regions, instability is analyzed as a function of equilibrium structure. It is shown that the total equilibrium radial force due to the ion channel and electron beam and also relativistic effect play a key role in the coupling of the radially polarized EM wave and space charge wave. Furthermore, some asymptotic behaviors such as weak and strong ion channel, nonrelativistic case and cutoff frequencies are discussed. This instability could be used as an amplification mechanism for radially polarized EM waves in a beam-plasma system where a relativistic electron beam is guided by the ion channel.

  16. HEAVY ION HEATING DUE TO INTERACTIONS WITH OUTWARD AND INWARD ALFVEN WAVE PACKETS

    SciTech Connect

    Galinsky, V. L.; Shevchenko, V. I.

    2012-06-01

    The study of simultaneous cyclotron interactions of heavy ions with outward- and inward-propagating Alfven wave packets in the solar wind was self-consistently conducted with wave-packet dynamics. It was shown that, even when the ratio of intensities of the Alfven waves propagating from the Sun and the inward propagating waves are rather large (a factor of 10 or more), the distribution function of the ions simultaneously interacting with both of the wave packets drastically differs from the distribution function formed by the interaction of ions with waves only propagating from the Sun. In the latter case, the ions acquire a shell-like distribution; in the former case, a new non-shell-type distribution with much larger effective temperatures is formed. The temporal dynamics of the ion-distribution function and the self-consistent modification of the wave-power spectral density for both the outward and inward waves were also investigated. The results refute claims by Isenberg and Hollweg that the outward-propagating waves generate the inward waves through the instability of their resonant particle shell distribution.

  17. Combined effect of pulsed electromagnetic field and sound wave on In vitro and In vivo neural differentiation of human mesenchymal stem cells.

    PubMed

    Choi, Yun-Kyong; Urnukhsaikhan, Enerelt; Yoon, Hee-Hoon; Seo, Young-Kwon; Cho, Hyunjin; Jeong, Jong-Seob; Kim, Soo-Chan; Park, Jung-Keug

    2017-01-01

    Biophysical wave stimulus has been used as an effective tool to promote cellular maturation and differentiation in the construction of engineered tissue. Pulsed electromagnetic fields (PEMFs) and sound waves have been selected as effective stimuli that can promote neural differentiation. The aim of this study was to investigate the synergistic effect of PEMFs and sound waves on the neural differentiation potential in vitro and in vivo using human bone marrow mesenchymal stem cells (hBM-MSCs). In vitro, neural-related genes in hBM-MSCs were accelerated by the combined exposure to both waves more than by individual exposure to PEMFs or sound waves. The combined wave also up-regulated the expression of neural and synaptic-related proteins in a three-dimensional (3-D) culture system through the phosphorylation of extracellular signal-related kinase. In a mouse model of photochemically induced ischemia, exposure to the combined wave reduced the infarction volume and improved post-injury behavioral activity. These results indicate that a combined stimulus of biophysical waves, PEMFs and sound can enhance and possibly affect the differentiation of MSCs into neural cells. Our study is meaningful for highlighting the potential of combined wave for neurogenic effects and providing new therapeutic approaches for neural cell therapy. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 33:201-211, 2017.

  18. Main Characteristics of the VLF Magnetic Field Waves Recorded by the Search Coil Magnetometer Experiment Onboard the CUSP Sounding Rocket

    NASA Astrophysics Data System (ADS)

    Pinçon, J.; Krasnoselskikh, V.; de Feraudy, H.; Rezeau, L.; Robert, P.; Pfaff, R. F.

    2003-12-01

    The CUSP rocket is a NASA Black Brant X sounding rocket dedicated to the exploration of the electrodynamic coupling, pulsations, and acceleration processes in the dayside cusp and the boundary layer interface. The launch occured on December 14, 2002, from Ny Åleysund, Spitzbergen (79° N) during Bz negative conditions. We present the magnetic field waves measurement collected in the frequency range [10 Hz - 10 kHz] by the three axis Search Coil Magnetometer (SCM) experiment onboard CUSP. The observations reveal the presence of intense field fluctuations corresponding to ELF hiss which is only seen on closed field lines and hence can be used to define the magnetic boundary of the cusp. Several data analysis techniques were applied to the 3 components of the magnetic field fluctuations associated with the ELF hiss to obtain information regarding the wave polarization and the wave vector directions. The magnetic field wave data are compared with simultaneous observations of electric field wave data to further enhance our understanding of these wave phenomena. The main results coming from this detailed study are presented and discussed.

  19. Ion-acoustic super rogue waves in ultracold neutral plasmas with nonthermal electrons

    SciTech Connect

    El-Tantawy, S. A.; El-Bedwehy, N. A.; El-Labany, S. K.

    2013-07-15

    The ion-acoustic rogue waves in ultracold neutral plasmas consisting of ion fluid and nonthermal electrons are reported. A reductive perturbation method is used to obtain a nonlinear Schrödinger equation for describing the system and the modulation instability of the ion-acoustic wave is analyzed. The critical wave number k{sub c}, which indicates where the modulational instability sets in, has been determined. Moreover, the possible region for the ion-acoustic rogue waves to exist is defined precisely. The effects of the nonthermal parameter β and the ions effective temperature ratio σ{sub *} on the critical wave number k{sub c} are studied. It is found that there are two critical wave numbers in our plasma system. For low wave number, increasing β would lead to cringe k{sub c} until β approaches to its critical value β{sub c}, then further increase of β beyond β{sub c} would enhance the values of k{sub c}. For large wave numbers, the increase of β would lead to a decrease of k{sub c}. However, increasing σ{sub *} would lead to the reduction of k{sub c} for all values of the wave number. The dependence of the rogue waves profile on the plasma parameters is numerically examined. It is found that the rogue wave amplitudes have complex behavior with increasing β. Furthermore, the enhancement of σ{sub *} and the carrier wave number k reduces the rogue wave amplitude. It is noticed that near to the critical wave number, the rogue wave amplitude becomes high, but it shrinks whenever we stepped away from k{sub c}. The implications of our results in laboratory ultracold neutral plasma experiments are briefly discussed.

  20. The Interaction of Sound and Shock Waves with Flexible Porous Materials

    NASA Astrophysics Data System (ADS)

    Abbott, James Fuller

    Several topics are studied which illustrate the role of flexibility in determining the acoustical properties of flexible porous materials. A power balance relation is obtained for the flexible porous material which explicitly identifies two loss mechanisms for sound absorption: the losses due to the irreversible deformation of the structure, and those attributed to the viscous drag between the fluid and the structure. The finite flexible porous layer backed by a rigid wall is then considered. Irreversible deformation of the structure is shown to be the dominant loss mechanism for closed layers. Three departures from the basic model-- a porous layer with anisotropic flow resistance and structure factor, periodic structures consisting of porous layers separated by air gaps, and the porous medium in bulk with mean fluid flow--are considered. The reflection of shock waves is also studied, and a quasi-linear theory is developed which reproduces the principal features of experimental results obtained previously by Ingard. The theory assumes that the propagating pulses in the air and structure are linear and the gross, zeroth order motion of the porous layer is modeled by including its energy and momentum in the conservation equations; these equations compare the system just before and just after the reflection of the incident shock from the front surface of the layer. The substantial motion of the layer and its dragging against a constraining boundary (in this case the walls of the shock tube) are found to introduce a dependence of the front reflection coefficient and maximal layer deformation on the peak pressure of the incident shock. Lastly, we address the question of measurement of the complex compressibility K, a key parameter used to describe the dynamics of a given flexible porous material. The standard long-wavelength assumption used to determine K from experimental measurements of the frequency dependent velocity transfer function across a sample is shown to

  1. Multiple Scattering of Sound by Internal Waves and Acoustic Characterization of Internal Wave Fields in Deep and Shallow Water

    DTIC Science & Technology

    2005-09-30

    approximation in many practical situations. The equation for the average acoustic field in the statistically homogeneous in horizontal plane stratified...using diagrammatic technique similar to the one used in the theory of wave propagation in the homogeneous medium. The mass operator was calculated...perturbations on various eigenrays due to the horizontal refraction induced by internal waves with the Garrett-Munk spectrum: rigorous internal wave model

  2. Lower Hybrid Oscillations in Multicomponent Space Plasmas Subjected to Ion Cyclotron Waves

    NASA Technical Reports Server (NTRS)

    Khazanov, G. V.; Krivorutsky, E. N.; Moore, T. E.; Liemohn, M. W.; Horwitz, J. L.

    1997-01-01

    It is found that in multicomponent plasmas subjected to Alfven or fast magnetosonic waves, such as are observed in regions of the outer plasmasphere and ring current-plasmapause overlap, lower hybrid oscillations are generated. The addition of a minor heavy ion component to a proton-electron plasma significantly lowers the low-frequency electric wave amplitude needed for lower hybrid wave excitation. It is found that the lower hybrid wave energy density level is determined by the nonlinear process of induced scattering by ions and electrons; hydrogen ions in the region of resonant velocities are accelerated; and nonresonant particles are weakly heated due to the induced scattering. For a given example, the light resonant ions have an energy gain factor of 20, leading to the development of a high-energy tail in the H(+) distribution function due to low-frequency waves.

  3. Generation of waves in the Venus mantle by the ion acoustic beam instability

    NASA Technical Reports Server (NTRS)

    Huba, J. D.

    1993-01-01

    The ion acoustic beam instability is suggested as a mechanism to produce wave turbulence observed in the Venus mantle at frequencies 100 Hz and 730 Hz. The plasma is assumed to consist of a stationary cold O(+) ion plasma and a flowing, shocked solar wind plasma. The O(+) ions appear as a beam relative to the flowing ionosheath plasma which provides the free energy to drive the instability. The plasma is driven unstable by inverse electron Landau damping of an ion acoustic wave associated with the cold ionospheric O(+) ions. The instability can directly generate the observed 100 Hz waves in the Venus mantle as well as the observed 730 Hz waves through the Doppler shift of the frequency caused by the satellite motion.

  4. Electric Field Observations of Plasma Convection, Shear, Alfven Waves, and other Phenomena Observed on Sounding Rockets in the Cusp and Boundary Layer

    NASA Technical Reports Server (NTRS)

    Pfaff, R. F.

    2009-01-01

    On December 14,2002, a NASA Black Brant X sounding rocket was launched equatorward from Ny Alesund, Spitzbergen (79 N) into the dayside cusp and subsequently cut across the open/closed field line boundary, reaching an apogee of771 km. The launch occurred during Bz negative conditions with strong By negative that was changing during the flight. SuperDarn (CUTLASS) radar and subsequent model patterns reveal a strong westward/poleward convection, indicating that the rocket traversed a rotational reversal in the afternoon merging cell. The payload returned DC electric and magnetic fields, plasma waves, energetic particle, suprathermal electron and ion, and thermal plasma data. We provide an overview of the main observations and focus on the DC electric field results, comparing the measured E x B plasma drifts in detail with the CUTLASS radar observations of plasma drifts gathered simultaneously in the same volume. The in situ DC electric fields reveal steady poleward flows within the cusp with strong shears at the interface of the closed/open field lines and within the boundary layer. We use the observations to discuss ionospheric signatures of the open/closed character of the cusp/low latitude boundary layer as a function of the IMF. The electric field and plasma density data also reveal the presence of very strong plasma irregularities with a large range of scales (10 m to 10 km) that exist within the open field line cusp region yet disappear when the payload was equatorward of the cusp on closed field lines. These intense low frequency wave observations are consistent with strong scintillations observed on the ground at Ny Alesund during the flight. We present detailed wave characteristics and discuss them in terms of Alfven waves and static irregularities that pervade the cusp region at all altitudes.

  5. Investigations into the Influence of Heavy Ions on EMIC Wave Propagation in the Earth's Magnetosphere

    NASA Astrophysics Data System (ADS)

    Keller, S.; Kim, E. H.; Johnson, J.

    2015-12-01

    Geomagnetic pulsations in the Pc1 frequency range (0.2 to 5.0 Hz), which are known as electromagnetic ion cyclotron (EMIC) waves, are often observed at magnetically conjugate locations by spacecraft in the equatorial magnetosphere and ground-based stations. One difficulty in linking the propagation of detected radiation between these regions is the presence of stop bands near the heavy ion cyclotron resonance locations. Recent full wave calculations (Kim and Johnson, Full wave modeling of EMIC waves in the Earth's magnetosphere, 2015 AGU fall meeting) demonstrate how EMIC waves propagate to higher magnetic latitudes in an electron-proton-He+ plasma. However, while the heavy ion concentration can be large during the solar maximum and geomagnetic storms, they adopted a 5% He+ plasma. In this study, we explore the roles of heavy ion (He+ and O+) concentrations on the levels of EMIC wave energy that reach lower altitudes using a two-dimensional, finite element, full wave model. The Poynting flux and polarization of the emissions are used to monitor the propagation and absorption of wave energy, as well as mode coupling between left- and right-hand circularly polarized modes. Due to the increase in heavy ion populations in the magnetosphere, the consequences that geomagnetic storms have on EMIC wave propagation are also discussed.

  6. Multi-dimensional instability of obliquely propagating ion acoustic solitary waves in electron-positron-ion superthermal magnetoplasmas

    SciTech Connect

    EL-Shamy, E. F.

    2014-08-15

    The solitary structures of multi–dimensional ion-acoustic solitary waves (IASWs) have been considered in magnetoplasmas consisting of electron-positron-ion with high-energy (superthermal) electrons and positrons are investigated. Using a reductive perturbation method, a nonlinear Zakharov-Kuznetsov equation is derived. The multi-dimensional instability of obliquely propagating (with respect to the external magnetic field) IASWs has been studied by the small-k (long wavelength plane wave) expansion perturbation method. The instability condition and the growth rate of the instability have been derived. It is shown that the instability criterion and their growth rate depend on the parameter measuring the superthermality, the ion gyrofrequency, the unperturbed positrons-to-ions density ratio, the direction cosine, and the ion-to-electron temperature ratio. Clearly, the study of our model under consideration is helpful for explaining the propagation and the instability of IASWs in space observations of magnetoplasmas with superthermal electrons and positrons.

  7. Effect of two ion species on the propagation of shear Alfven waves of small transverse scale

    SciTech Connect

    Vincena, S. T.; Morales, G. J.; Maggs, J. E.

    2010-05-15

    The results of a theoretical modeling study and experimental investigation of the propagation properties of shear Alfven waves of small transverse scale in a plasma with two ion species are reported. In the two ion plasma, depending on the mass of the heavier species, ion kinetic effects can become prominent, and significant parallel electric fields result in electron acceleration. The theory predicts the appearance of frequency propagation gaps at the ion-ion hybrid frequency and between harmonics of the lower cyclotron frequency. Within these frequency bands spatial structures arise that mix the cone-propagation characteristics of Alfven waves with radially expanding ion Bernstein modes. The experiments, performed at the Basic Plasma Science Facility (BaPSF) at UCLA, consist of the spatial mapping of shear waves launched by a loop antenna. Although a variety of two ion-species combinations were explored, only results from a helium-neon mix are reported. A clear signature of a shear wave propagation gap, as well as propagation between multiple harmonics, is found for this gas combination. The evanescence of shear waves beyond the reflection point at the ion-ion hybrid frequency in the presence of an axial magnetic field gradient is also documented.

  8. Nonlinear propagation of ion-acoustic waves through the Burgers equation in weakly relativistic plasmas

    NASA Astrophysics Data System (ADS)

    Hafez, M. G.; Talukder, M. R.; Ali, M. Hossain

    2017-03-01

    The Burgers equation is obtained to study the characteristics of nonlinear propagation of ion-acoustic shock, singular kink, and periodic waves in weakly relativistic plasmas containing relativistic thermal ions, nonextensive distributed electrons, Boltzmann distributed positrons, and kinematic viscosity of ions using the well-known reductive perturbation technique. This equation is solved by employing the (G'/G)-expansion method taking unperturbed positron-to-electron concentration ratio, electron-to-positron temperature ratio, strength of electrons nonextensivity, ion kinematic viscosity, and weakly relativistic streaming factor. The influences of plasma parameters on nonlinear propagation of ion-acoustic shock, periodic, and singular kink waves are displayed graphically and the relevant physical explanations are described. It is found that these parameters extensively modify the shock structures excitation. The obtained results may be useful in understanding the features of small but finite amplitude localized relativistic ion-acoustic shock waves in an unmagnetized plasma system for some astrophysical compact objects and space plasmas.

  9. Dust negative ion acoustic shock waves in a dusty multi-ion plasma with positive dust charging current

    SciTech Connect

    Duha, S. S.

    2009-11-15

    Recent analysis of Mamun et al.[ Phys. Lett. A 373, 2355 (2009)], who considered electrons, light positive ions, heavy negative ions, and extremely massive (few micron size) charge fluctuating dust, has been extended by positive dust charging current, i.e., considering the charging currents for positively charged dust grains. A dusty multi-ion plasma system consisting of electrons, light positive ions, negative ions, and extremely massive (few micron size) charge fluctuating stationary dust have been considered. The electrostatic shock waves associated with negative ion dynamics and dust charge fluctuation have been investigated by employing the reductive perturbation method. It has been shown that the dust charge fluctuation is a source of dissipation and is responsible for the formation of dust negative ion acoustic (DNIA) shock structures. The basic features of such DNIA shock structures have been identified. The findings of this investigation may be useful in understanding the laboratory phenomena and space dusty plasmas.

  10. Measurement of Field Aligned Electron and Ion Densities and Ducts from the Whistler and Z Mode Radio Sounding from IMAGE

    NASA Astrophysics Data System (ADS)

    Sonwalkar, V. S.; Hazra, S.; Mayank, K.; Reddy, A.; Liu, Y.; Carpenter, D. L.

    2013-12-01

    We present recent results from the application of whistler mode (WM) and Z mode (ZM) radio sounding experiments from the IMAGE satellite to the magnetospheric plasma diagnostics. A recently developed WM radio sounding method [Sonwalkar et al., JGR, 116, A11210, doi:10.1029/2011JA016759, 2011] was applied to 200 cases of WM echoes observed within the plasmasphere to measure field aligned electron density (Ne) and ion densities (NH+, NHe+, NO+) for L~1.6 -4, altitude <5000 km, Kp ~1-7, and F10.7 ~ 72-110 (low solar activity). The measured plasma parameters are in general consistent with the past space borne (e.g. CHAMP, DMSP, Alouette, ISIS, AE) and ground (e.g. ionosonde) measurements, but show significant differences from those predicted by IRI-2012 and GCPM models. We believe our measurements will lead to an improved model of electron and ion densities at <5000 km within the plasmasphere. The WM radio sounding method was applied to a case study of the variation of plasma parameters at L~2 during the development of a major storm, from quiet conditions and subsequent recovery, followed by a moderate and minor storm. Our study showed that relative to the preceding quiet time: (1) There was depletion in electron density, H+, He+ and enhancement in O+ ions leading to increase in O+-H+ transition height; (2) The recovery period of electrons and individual ions was different; (3) A similar trend in the variation of electron density, H+, O+ was observed after the moderate storm and the minor storm but He+ was not affected. Following a ray tracing technique originally developed for whistler mode sounding, we analyzed the fast nonducted and ducted Z mode echoes to obtain field aligned electron density and duct parameters (duct width and enhancement) from the measured dispersion of Z mode echoes. With the help of two case studies, we illustrate that fast Z mode echoes provide measurement of electron density at altitudes <10,000 km and duct width and enhancement within an

  11. Energy density of standing sound waves at the radiation-dominated phase of the universe expansion (hydrodynamic derivation)

    NASA Astrophysics Data System (ADS)

    Inogamov, N. A.; Sunyaev, R. A.

    2015-12-01

    In the early Universe up to hydrogen recombination in the Universe, the radiation pressure was much greater than the pressure of baryons and electrons. Moreover, the energy density of cosmic microwave background (CMB) photons was greater than or close to the energy density contained in the rest mass of baryonic matter, i.e., the primordial plasma was a radiated-dominated one and the adiabatic index was close to 4/3. The small density perturbations from which the observed galaxies have grown grew as long as the characteristic perturbation scales exceeded the horizon of the Universe сt at that time. On smaller scales, the density perturbations were standing sound waves. Radiative viscosity and heat conduction must have led to the damping of sound waves on very small scales. After the discovery of the cosmic microwave background, J. Silk calculated the scales of this damping, which is now called Silk damping, knowing the CMBtemperature and assuming the density of baryons and electrons. Observations with the South Pole Telescope, the Atacama Cosmology Telescope, and the Planck satellite have revealed the predicted damping of acoustic peaks in the CMB power spectrum and confirmed one important prediction of the theory. In 1970, R.A. Sunyaev and Ya.B. Zeldovich showed that such energy release in the early Universe should lead to characteristic deviations of the CMB spectrum from the Planck one. The development of the technology of cryogenic detectors of submillimeter and millimeter wavelength radiation has made it possible to measure the CMB spectral distortions at 10-8 of its total intensity (PIXIE). This has sharply increased the interest of theoretical cosmologists in the problem of energy release when smallscale sound waves are damped. We have derived a relativistic formula for the energy of a standing sound wave in a photon-baryon-electron plasma from simple hydrodynamic and thermodynamic relations. This formula is applicable for an arbitrary relation between the

  12. Resonant behaviour of MHD waves on magnetic flux tubes. I - Connection formulae at the resonant surfaces. II - Absorption of sound waves by sunspots

    NASA Technical Reports Server (NTRS)

    Sakurai, Takashi; Goossens, Marcel; Hollweg, Joseph V.

    1991-01-01

    The present method of addressing the resonance problems that emerge in such MHD phenomena as the resonant absorption of waves at the Alfven resonance point avoids solving the fourth-order differential equation of dissipative MHD by recourse to connection formulae across the dissipation layer. In the second part of this investigation, the absorption of solar 5-min oscillations by sunspots is interpreted as the resonant absorption of sounds by a magnetic cylinder. The absorption coefficient is interpreted (1) analytically, under certain simplifying assumptions, and numerically, under more general conditions. The observed absorption coefficient magnitude is explained over suitable parameter ranges.

  13. Squeezing of Ion Populations and Peaks in Traveling Wave Ion Mobility Separations and Structures for Lossless Ion Manipulations using Compression Ratio Ion Mobility Programming

    SciTech Connect

    Garimella, Venkata BS; Hamid, Ahmed M.; Deng, Liulin; Ibrahim, Yehia M.; Webb, Ian K.; Baker, Erin M.; Prost, Spencer A.; Norheim, Randolph V.; Anderson, Gordon A.; Smith, Richard D.

    2016-11-02

    In this work, we report an approach for spatial and temporal gas phase ion population manipulation, and demonstrate its application for the collapse of the ion distributions in ion mobility (IM) separations into tighter packets providing higher sensitivity measurements in conjunction with mass spectrometry (MS). We do this for ions moving from a conventionally traveling wave (TW)-driven region to a region where the TW is intermittently halted or ‘stuttered’. This approach causes the ion packets spanning a number of TW-created traveling traps (TT) to be redistributed into fewer TT, resulting in spatial compression. The degree of spatial compression is controllable and determined by the ratio of stationary time of the TW in the second region to its moving time. This compression ratio ion mobility programming (CRIMP) approach has been implemented using Structures for Lossless Ion Manipulations (SLIM) in conjunction with MS. CRIMP with the SLIM-MS platform is shown to provide increased peak intensities, reduced peak widths, and improved S/N ratios with MS detection. CRIMP also provides a foundation for extremely long path length and multi-pass IM separations in SLIM providing greatly enhanced IM resolution by reducing the detrimental effects of diffusional peak broadening due to increasing peak widths.

  14. Heating of ions by Alfvén waves via nonresonant interactions.

    PubMed

    Wang, C B; Wu, C S; Yoon, P H

    2006-03-31

    Finite-amplitude intrinsic Alfvén waves exist pervasively in astrophysical and solar-terrestrial environment. It is generally believed that linear wave-particle resonant interaction between thermal protons and Alfvén waves is ineffective when the proton beta is low. However, this Letter demonstrates that the ions can be heated by Alfvén waves via nonresonant nonlinear interaction. Contrary to the customary expectation, it is found that the lower the plasma beta value, the more effective is the heating process. It is also shown that the ion temperature increase is more prominent along perpendicular direction.

  15. Dust ion acoustic solitary waves in a collisional dusty plasma with dust grains having Gaussian distribution

    SciTech Connect

    Maitra, Sarit; Banerjee, Gadadhar

    2014-11-15

    The influence of dust size distribution on the dust ion acoustic solitary waves in a collisional dusty plasma is investigated. It is found that dust size distribution changes the amplitude and width of a solitary wave. A critical wave number is derived for the existence of purely damping mode. A deformed Korteweg-de Vries (dKdV) equation is obtained for the propagation of weakly nonlinear dust ion acoustic solitary waves and the effect of different plasma parameters on the solution of this equation is also presented.

  16. Ultrahigh resolution simulations of mode converted ion cyclotron waves and lower hybrid waves

    NASA Astrophysics Data System (ADS)

    Wright, J. C.; Bonoli, P. T.; D'Azevedo, E.; Brambilla, M.

    2004-12-01

    Full wave studies of mode conversion (MC) processes in toroidal plasmas have required prohibitive amount of computer resources in the past because of the disparate spatial scales involved. The TORIC code [Brambilla, Nucl. Fusion 38 (1998) 1805] solves the linear sixth order reduced wave equation for the ion cyclotron range of frequencies (ICRF), in toroidal geometry using a Fourier representation for the poloidal dimension and finite elements in the flux dimension. The range of problems that TORIC can do has been extended through both new serial algorithms and parallelization of memory and processing. The implementation of out-of-core memory management, FFT convolutions, and improved memory management brought MC studies just into range of the serial version of the code running on a NERSC Cray SV1. Some simple tests and arguments show that more resolution than is possible on a single processor system is needed to fully resolve these scenarios. By distributing the large linear system across many processors in conjunction with the out-of-core technique, the resolution limitations are effectively removed. ScaLAPACK is used to do the linear algebra operations and message passing interface (MPI) is used to distribute the significant amount of post-processing. The new parallel version of the code can easily do the most difficult MC problems on present day tokamaks (Alcator C-Mod and Asdex-Upgrade), with only 32 pc from a local Beowulf cluster. Using 48 or more processors admits us to problems in the lower hybrid range of frequencies.

  17. Ion acoustic waves at comet 67P/Churyumov-Gerasimenko. Observations and computations

    NASA Astrophysics Data System (ADS)

    Gunell, H.; Nilsson, H.; Hamrin, M.; Eriksson, A.; Odelstad, E.; Maggiolo, R.; Henri, P.; Vallieres, X.; Altwegg, K.; Tzou, C.-Y.; Rubin, M.; Glassmeier, K.-H.; Stenberg Wieser, G.; Simon Wedlund, C.; De Keyser, J.; Dhooghe, F.; Cessateur, G.; Gibbons, A.

    2017-03-01

    Context. On 20 January 2015 the Rosetta spacecraft was at a heliocentric distance of 2.5 AU, accompanying comet 67P/Churyumov-Gerasimenko on its journey toward the Sun. The Ion Composition Analyser (RPC-ICA), other instruments of the Rosetta Plasma Consortium, and the ROSINA instrument made observations relevant to the generation of plasma waves in the cometary environment. Aims: Observations of plasma waves by the Rosetta Plasma Consortium Langmuir probe (RPC-LAP) can be explained by dispersion relations calculated based on measurements of ions by the Rosetta Plasma Consortium Ion Composition Analyser (RPC-ICA), and this gives insight into the relationship between plasma phenomena and the neutral coma, which is observed by the Comet Pressure Sensor of the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis instrument (ROSINA-COPS). Methods: We use the simple pole expansion technique to compute dispersion relations for waves on ion timescales based on the observed ion distribution functions. These dispersion relations are then compared to the waves that are observed. Data from the instruments RPC-LAP, RPC-ICA and the mutual impedance probe (RPC-MIP) are compared to find the best estimate of the plasma density. Results: We find that ion acoustic waves are present in the plasma at comet 67P/Churyumov-Gerasimenko, where the major ion species is H2O+. The bulk of the ion distribution is cold, kBTi = 0.01 eV when the ion acoustic waves are observed. At times when the neutral density is high, ions are heated through acceleration by the solar wind electric field and scattered in collisions with the neutrals. This process heats the ions to about 1 eV, which leads to significant damping of the ion acoustic waves. Conclusions: In conclusion, we show that ion acoustic waves appear in the H2O+ plasmas at comet 67P/Churyumov-Gerasimenko and how the interaction between the neutral and ion populations affects the wave properties. Computer code for the dispersion analysis is

  18. Roles of positively charged heavy ions and degenerate plasma pressure on cylindrical and spherical ion acoustic solitary waves

    NASA Astrophysics Data System (ADS)

    Hossen, M. R.; Nahar, L.; Sultana, S.; Mamun, A. A.

    2014-09-01

    The properties of heavy-ion-acoustic (HIA) solitary structures associated with the nonlinear propagation of cylindrical and spherical electrostatic perturbations in an unmagnetized, collisionless dense plasma system has been investigated theoretically. Our considered model contains degenerate electron and inertial light ion fluids, and positively charged static heavy ions, which is valid for both of the non-relativistic and ultra-relativistic limits. The Korteweg-de Vries (K-dV) and modified K-dV (mK-dV) equations have been derived by employing the reductive perturbation method, and numerically examined in order. It has been found that the effect of degenerate pressure and number density of electron and inertial light ion fluids, and positively charged static heavy ions significantly modify the basic features of HIA solitary waves. It is also noted that the inertial light ion fluid is the source of dispersion for HIA waves and is responsible for the formation of solitary waves. The basic features and the underlying physics of HIA solitary waves, which are relevant to some astrophysical compact objects, are briefly discussed.

  19. Ion temperature effects on magnetotail Alfvén wave propagation and electron energization: ION TEMPERATURE EFFECTS ON ALFVÉN WAVES

    SciTech Connect

    Damiano, P. A.; Johnson, J. R.; Chaston, C. C.

    2015-07-01

    A new 2-D self-consistent hybrid gyrofluid-kinetic electron model in dipolar coordinates is presented and used to simulate dispersive-scale Alfvén wave pulse propagation from the equator to the ionosphere along an L = 10 magnetic field line. The model is an extension of the hybrid MHD-kinetic electron model that incorporates ion Larmor radius corrections via the kinetic fluid model of Cheng and Johnson (1999). It is found that consideration of a realistic ion to electron temperature ratio decreases the propagation time of the wave from the plasma sheet to the ionosphere by several seconds relative to a ρi=0 case (which also implies shorter timing for a substorm onset signal) and leads to significant dispersion of wave energy perpendicular to the ambient magnetic field. Additionally, ion temperature effects reduce the parallel current and electron energization all along the field line for the same magnitude perpendicular electric field perturbation.

  20. Ion Heating in Inhomogeneous Expanding Solar Wind Plasma: The Role of Parallel and Oblique Ion-cyclotron Waves

    NASA Astrophysics Data System (ADS)

    Ozak, N.; Ofman, L.; Viñas, A.-F.

    2015-01-01

    Remote sensing observations of coronal holes show that heavy ions are hotter than protons and their temperature is anisotropic. In-situ observations of fast solar wind streams provide direct evidence for turbulent Alfvén wave spectrum, left-hand polarized ion-cyclotron waves, and He++ - proton drift in the solar wind plasma, which can produce temperature anisotropies by resonant absorption and perpendicular heating of the ions. Furthermore, the solar wind is expected to be inhomogeneous on decreasing scales approaching the Sun. We study the heating of solar wind ions in inhomogeneous plasma with a 2.5D hybrid code. We include the expansion of the solar wind in an inhomogeneous plasma background, combined with the effects of a turbulent wave spectrum of Alfvénic fluctuations and initial ion-proton drifts. We study the influence of these effects on the perpendicular ion heating and cooling and on the spectrum of the magnetic fluctuations in the inhomogeneous background wind. We find that inhomogeneities in the plasma lead to enhanced heating compared to the homogenous solar wind, and the generation of significant power of oblique waves in the solar wind plasma. The cooling effect due to the expansion is not significant for super-Alfvénic drifts, and is diminished further when we include an inhomogeneous background density. We reproduce the ion temperature anisotropy seen in observations and previous models, which is present regardless of the perpendicular cooling due to solar wind expansion. We conclude that small scale inhomogeneities in the inner heliosphere can significantly affect resonant wave ion heating.

  1. ION HEATING IN INHOMOGENEOUS EXPANDING SOLAR WIND PLASMA: THE ROLE OF PARALLEL AND OBLIQUE ION-CYCLOTRON WAVES

    SciTech Connect

    Ozak, N.; Ofman, L.; Viñas, A.-F.

    2015-01-20

    Remote sensing observations of coronal holes show that heavy ions are hotter than protons and their temperature is anisotropic. In-situ observations of fast solar wind streams provide direct evidence for turbulent Alfvén wave spectrum, left-hand polarized ion-cyclotron waves, and He{sup ++} - proton drift in the solar wind plasma, which can produce temperature anisotropies by resonant absorption and perpendicular heating of the ions. Furthermore, the solar wind is expected to be inhomogeneous on decreasing scales approaching the Sun. We study the heating of solar wind ions in inhomogeneous plasma with a 2.5D hybrid code. We include the expansion of the solar wind in an inhomogeneous plasma background, combined with the effects of a turbulent wave spectrum of Alfvénic fluctuations and initial ion-proton drifts. We study the influence of these effects on the perpendicular ion heating and cooling and on the spectrum of the magnetic fluctuations in the inhomogeneous background wind. We find that inhomogeneities in the plasma lead to enhanced heating compared to the homogenous solar wind, and the generation of significant power of oblique waves in the solar wind plasma. The cooling effect due to the expansion is not significant for super-Alfvénic drifts, and is diminished further when we include an inhomogeneous background density. We reproduce the ion temperature anisotropy seen in observations and previous models, which is present regardless of the perpendicular cooling due to solar wind expansion. We conclude that small scale inhomogeneities in the inner heliosphere can significantly affect resonant wave ion heating.

  2. Calculating Speed of Sound

    NASA Astrophysics Data System (ADS)

    Bhatnagar, Shalabh

    2017-01-01

    Sound is an emerging source of renewable energy but it has some limitations. The main limitation is, the amount of energy that can be extracted from sound is very less and that is because of the velocity of the sound. The velocity of sound changes as per medium. If we could increase the velocity of the sound in a medium we would be probably able to extract more amount of energy from sound and will be able to transfer it at a higher rate. To increase the velocity of sound we should know the speed of sound. If we go by the theory of classic mechanics speed is the distance travelled by a particle divided by time whereas velocity is the displacement of particle divided by time. The speed of sound in dry air at 20 °C (68 °F) is considered to be 343.2 meters per second and it won't be wrong in saying that 342.2 meters is the velocity of sound not the speed as it's the displacement of the sound not the total distance sound wave covered. Sound travels in the form of mechanical wave, so while calculating the speed of sound the whole path of wave should be considered not just the distance traveled by sound. In this paper I would like to focus on calculating the actual speed of sound wave which can help us to extract more energy and make sound travel with faster velocity.

  3. The Backward Electrostatic Ion-Cyclotron Wave, Fast Wave Current Drive, and Far-Infrared Laser Scattering

    NASA Astrophysics Data System (ADS)

    Goree, John Arlin

    1985-12-01

    The first observations of several radio frequency wave phenomena in a magnetized plasma are presented. The backward branch of the electrostatic ion-cyclotron wave, which was previously described in reports of theoretical but not experimental work, was observed. This hot magnetized plasma mode propagates for frequencies above each harmonic of the ion-cyclotron frequency. A phased antenna structure, inserted into a neon plasma, excited the wave. An experimental dispersion relation produced from probe measurements of the mode agrees with the dispersion relation predicted using linear theory. Fast wave current drive in a toroidal plasma was observed for the first time. A loop antenna launched the fast Alfven wave in the range of high ion-cyclotron harmonics, (omega)/(OMEGA) = O(10). Signals from magnetic loop probes, Langmuir probes, and FIR laser scattering revealed the identity of the mode. Using a single antenna to launch the wave into a plasma containing a unidirectional electron beam, the circulating current increased according to the rf power applied. This increase in current occurs when the plasma is sufficiently dense to support fast wave propagation. Fast wave current drive may be a desirable method of sustaining the toroidal current in a fusion reactor. A fast wave antenna also excites slow wave resonance cones, i.e., lower-hybrid waves, as shown here for the first time. This process occurs in the same frequency range of high ion-cyclotron harmonics as fast wave current drive, and may represent an undesirable loss mechanism. A far-infrared laser scattering diagnostic was developed for detecting coherent radio frequency waves. In this system, an unusual detection method employing two lock-in amplifiers reduced noise from rf pickup and broadband noise. A criterion is presented for its use. A new type of cathode for producing plasmas, used in the fast wave experiment, consists of a lanthanum-hexaboride emissive element heated by a graphite resistor. Inserted

  4. Energy transfer between energetic ring current H(+) and O(+) by electromagnetic ion cyclotron waves

    NASA Technical Reports Server (NTRS)

    Thorne, Richard M.; Horne, Richard B.

    1994-01-01

    Electromagnetic ion cyclotron (EMIC) waves in the frequency range below the helium gyrofrequency can be excited in the equatorial region of the outer magnetosphere by cyclotron resonant instability with anisotropic ring current H(+) ions. As the unducted waves propagate to higher latitudes, the wave normal should become highly inclined to the ambient magnetic field. Under such conditions, wave energy can be absorbed by cyclotron resonant interactions with ambient O(+), leading to ion heating perpendicular to the ambient magnetic field. Resonant wave absorption peaks in the vicinity of the bi-ion frequency and the second harmonic of the O(+) gyrofrequrency. This absorption should mainly occur at latitudes between 10 deg and 30 deg along auroral field lines (L is greater than or equal to 7) in the postnoon sector. The concomitant ion heating perpendicular to the ambient magnetic field can contribute to the isotropization and geomagnetic trapping of collapsed O(+) ion conics (or beams) that originate from a low-altitude ionospheric source region. During geomagnetic storms when the O(+) content of the magnetosphere is significantly enhanced, the absorption of EMIC waves should become more efficient, and it may contribute to the observed acceleration of O(+) ions of ionospheric origin up to ring current energies.

  5. Scattering of relativistic and ultra-relativistic electrons by obliquely propagating Electromagnetic Ion Cyclotron waves

    NASA Astrophysics Data System (ADS)

    Uzbekov, Bogdan; Shprits, Yuri Y.; Orlova, Ksenia

    2016-10-01

    Electromagnetic Ion Cyclotron (EMIC) waves are transverse plasma waves that are generated in the Earth magnetosphere by ring current protons with temperature anisotropy in three different bands: below the H+, He+ and O+ ion gyrofrequencies. EMIC events are enhanced during the main phase of a geomagnetic storm when intensifications in the electric field result in enhanced injections of ions and are usually confined to high-density regions just inside the plasmapause or within drainage plumes. EMIC waves are capable of scattering radiation belt electrons and thus provide an important link between the intensification of the electric field, ion populations, and radiation belt electrons. Bounce-averaged diffusion coefficients computed with the assumption of parallel wave propagation are compared to the results of the code that uses the full cold plasma dispersion relation taking into account oblique propagation of waves and higher-order resonances. We study the sensitivity of the scattering rates to a number of included higher-order resonances, wave spectral distribution parameters, wave normal angle distribution parameters, ambient plasma density, and ion composition. Inaccuracies associated with the neglect of higher-order resonances and oblique propagation of waves are compared to potential errors introduced by uncertainties in the model input parameters.

  6. Dust ion-acoustic rogue waves in a three-species ultracold quantum dusty plasmas

    SciTech Connect

    Sun, Wen-Rong; Tian, Bo Liu, Rong-Xiang; Liu, De-Yin

    2014-10-15

    Dust ion-acoustic (DIA) rogue waves are reported for a three-component ultracold quantum dusty plasma comprised of inertialess electrons, inertial ions, and negatively charged immobile dust particles. The nonlinear Schrödinger (NLS) equation appears for the low frequency limit. Modulation instability (MI) of the DIA waves is analyzed. Influence of the modulation wave number, ion-to-electron Fermi temperature ratio ρ and dust-to-ion background density ratio N{sub d} on the MI growth rate is discussed. The first- and second-order DIA rogue-wave solutions of the NLS equation are examined numerically. It is found that the enhancement of N{sub d} and carrier wave number can increase the envelope rogue-wave amplitudes. However, the increase of ρ reduces the envelope rogue-wave amplitudes. - Highlights: • The nonlinear Schrödinger equation is derived for the low frequency limit. • Modulational instability growth rate is discussed. • The first- and second-order dust ion-acoustic rogue waves are examined numerically.

  7. Evidence for two-dimensional solitary sound waves in a lipid controlled interface and its implications for biological signalling.

    PubMed

    Shrivastava, Shamit; Schneider, Matthias F

    2014-08-06

    Biological membranes by virtue of their elastic properties should be capable of propagating localized perturbations analogous to sound waves. However, the existence and the possible role of such waves in communication in biology remain unexplored. Here, we report the first observations of two-dimensional solitary elastic pulses in lipid interfaces, excited mechanically and detected by FRET. We demonstrate that the nonlinearity near a maximum in the susceptibility of the lipid monolayer results in solitary pulses that also have a threshold for excitation. These experiments clearly demonstrate that the state of the interface regulates the propagation of pulses both qualitatively and quantitatively. Finally, we elaborate on the striking similarity of the observed phenomenon to nerve pulse propagation and a thermodynamic basis of cell signalling in general.

  8. Bottom attenuation estimation using sound intensity fluctuations due to mode coupling by nonlinear internal waves in shallow water.

    PubMed

    Grigorev, Valery A; Katsnelson, Boris G; Lynch, James F

    2016-11-01

    Analyses of fluctuations of low frequency signals (300 ± 30 Hz) propagating in shallow water in the presence of nonlinear internal waves (NIWs) in the Shallow Water 2006 experiment are carried out. Signals were received by a vertical line array at a distance of ∼20 km from the source. A NIW train was moving totally inside of the acoustic track, and the angle between the wave front of the NIW and the acoustic track in the horizontal plane was ∼10°. It is shown that the spectrum of the sound intensity fluctuations contains peaks corresponding to the coupling of pairs of propagating modes. Analysis of spectra at different hydrophone depths, and also summed over depth allows the authors to estimate attenuation in the bottom sediments.

  9. Generalized wave envelope analysis of sound propagation in ducts with stepped noise source profiles and variable axial impedance

    NASA Technical Reports Server (NTRS)

    Baumeister, K. J.

    1975-01-01

    A finite difference formulation is presented for sound propagation in a rectangular two-dimensional duct without steady flow. Before the difference equations are formulated, the governing Helmholtz equation is first transformed to a form whose solution tends not to oscillate along the length of the duct. This transformation reduces the required number of grid points by an order of magnitude. Example solutions indicate that stepped noise source profiles have much higher attenuation than plane waves in a uniform impedance liner. Also, multiple stepped impedance liners are shown to have higher attenuation than uniform ducts if the impedances are chosen properly. For optimum noise reduction with axial variations in impedance, the numerical analysis indicates that for a plane wave input the resistance should be near zero at the entrance of a suppressor duct, while the reactance should be near the optimum value associated with the least-attenuated mode in a uniform duct.

  10. Ion acceleration by Alfvén waves on auroral field lines

    NASA Astrophysics Data System (ADS)

    Bingham, Robert; Eliasson, Bengt; Tito Mendonça, José; Stenflo, Lennart

    2013-05-01

    Observations of ion acceleration along auroral field lines at the boundary of the plasma sheet and tail lobe of the Earth show that the energy of the ions increases with decreasing density. The observations can be explained by ion acceleration through Landau resonance with kinetic Alfvén waves (KAWs) such that kA·vi = ωA, where kA is the wave vector, vi is the ion resonance velocity and ωA is the Alfvén wave frequency. The ion resonance velocities are proportional to the Alfvén velocity which increases with decreasing density. This is in agreement with the data if the process is occurring at the plasma sheet tail lobe boundary. A quasi-linear theory of ion acceleration by KAWs is presented. These ions propagate both down towards and away from the Earth. The paths of the Freja and Polar satellites indicate that the acceleration takes place between the two satellites, between 1Re and 5Re. The downward propagating ions develop a horseshoe-type of distribution which has a positive slope in the perpendicular direction. This type of distribution can produce intense lower hybrid wave activity, which is also observed. Finally, the filamentation of shear Alfvén waves is considered. It may be responsible for large-scale density striations. In memory of Padma Kant Shukla, a great scientist and a good friend.

  11. Role of DC Electric Fields and Wave Heating in Cavity Profiles of Depleted Density and Transverse Ion Acceleration in Laboratory and Space Plasmas

    NASA Astrophysics Data System (ADS)

    Koepke, M. E.; Reynolds, E. W.; Knudsen, D. J.

    2007-05-01

    Laboratory experiments on the WVU Q Machine, test-particle simulations, and Monte Carlo simulations are shown to provide evidence for explaining the inhomogeneity in both the plasma-density profile and the ion- temperature profile associated with cylindrically symmetric lower-hybrid cavities observed by the GEODESIC sounding rocket, the OEDIPUS-C sounding rocket, and the Freja satellite. Two potential contributions to the inhomogeneous profiles are identified. Both mechanisms (one dc and the other ac) rely on finite values of the Larmor radius and can result in nonlocal effects that deplete ion density within the cavity and enhance ion density immediately outside the cavity to form ion-gyroradius-scale shoulders encircling the cavity perimeter. In the absence of waves, a cylindrically symmetric, radial, DC electric field can be responsible for a polarization shift that produces such inhomogeneity in the density profile [1]. In the presence of waves, wave-induced transverse ion acceleration occurring within the cavity can produce such inhomogeneity in the density profile [2]. In combination, the two effects are shown to be comparable, necessitating an interpretation that includes both mechanisms for quantitative agreement. For the lab data, laser-induced fluorescence techniques provide high resolution in coordinate space and velocity space. [1] Reynolds et al., Inhomogeneity scale lengths in a magnetized, low temperature, collisionless, Q-machine plasma column containing perpendicular-velocity shear, Phys. Plasmas 13, 092106 (2006). [2] Knudsen et al., Lower-hybrid cavity density depletions as a result of transverse ion acceleration localized on the gyroradius scale, J. Geophys. Res. 109, A04212 (2004). This research is supported by NSF.

  12. Experimental and numerical characterization of the sound pressure in standing wave acoustic levitators.

    PubMed

    Stindt, A; Andrade, M A B; Albrecht, M; Adamowski, J C; Panne, U; Riedel, J

    2014-01-01

    A novel method for predictions of the sound pressure distribution in acoustic levitators is based on a matrix representation of the Rayleigh integral. This method allows for a fast calculation of the acoustic field within the resonator. To make sure that the underlying assumptions and simplifications are justified, this approach was tested by a direct comparison to experimental data. The experimental sound pressure distributions were recorded by high spatially resolved frequency selective microphone scanning. To emphasize the general applicability of the two approaches, the comparative studies were conducted for four different resonator geometries. In all cases, the results show an excellent agreement, demonstrating the accuracy of the matrix method.

  13. ENERGY CONSERVATION AND GRAVITY WAVES IN SOUND-PROOF TREATMENTS OF STELLAR INTERIORS. II. LAGRANGIAN CONSTRAINED ANALYSIS

    SciTech Connect

    Vasil, Geoffrey M.; Lecoanet, Daniel; Brown, Benjamin P.; Zweibel, Ellen G.; Wood, Toby S.

    2013-08-20

    The speed of sound greatly exceeds typical flow velocities in many stellar and planetary interiors. To follow the slow evolution of subsonic motions, various sound-proof models attempt to remove fast acoustic waves while retaining stratified convection and buoyancy dynamics. In astrophysics, anelastic models typically receive the most attention in the class of sound-filtered stratified models. Generally, anelastic models remain valid in nearly adiabatically stratified regions like stellar convection zones, but may break down in strongly sub-adiabatic, stably stratified layers common in stellar radiative zones. However, studying stellar rotation, circulation, and dynamos requires understanding the complex coupling between convection and radiative zones, and this requires robust equations valid in both regimes. Here we extend the analysis of equation sets begun in Brown et al., which studied anelastic models, to two types of pseudo-incompressible models. This class of models has received attention in atmospheric applications, and more recently in studies of white-dwarf supernova progenitors. We demonstrate that one model conserves energy but the other does not. We use Lagrangian variational methods to extend the energy conserving model to a general equation of state, and dub the resulting equation set the generalized pseudo-incompressible (GPI) model. We show that the GPI equations suitably capture low-frequency phenomena in both convection and radiative zones in stars and other stratified systems, and we provide recommendations for converting low-Mach number codes to this equation set.

  14. Energy Conservation and Gravity Waves in Sound-proof Treatments of Stellar Interiors. II. Lagrangian Constrained Analysis

    NASA Astrophysics Data System (ADS)

    Vasil, Geoffrey M.; Lecoanet, Daniel; Brown, Benjamin P.; Wood, Toby S.; Zweibel, Ellen G.

    2013-08-01

    The speed of sound greatly exceeds typical flow velocities in many stellar and planetary interiors. To follow the slow evolution of subsonic motions, various sound-proof models attempt to remove fast acoustic waves while retaining stratified convection and buoyancy dynamics. In astrophysics, anelastic models typically receive the most attention in the class of sound-filtered stratified models. Generally, anelastic models remain valid in nearly adiabatically stratified regions like stellar convection zones, but may break down in strongly sub-adiabatic, stably stratified layers common in stellar radiative zones. However, studying stellar rotation, circulation, and dynamos requires understanding the complex coupling between convection and radiative zones, and this requires robust equations valid in both regimes. Here we extend the analysis of equation sets begun in Brown et al., which studied anelastic models, to two types of pseudo-incompressible models. This class of models has received attention in atmospheric applications, and more recently in studies of white-dwarf supernova progenitors. We demonstrate that one model conserves energy but the other does not. We use Lagrangian variational methods to extend the energy conserving model to a general equation of state, and dub the resulting equation set the generalized pseudo-incompressible (GPI) model. We show that the GPI equations suitably capture low-frequency phenomena in both convection and radiative zones in stars and other stratified systems, and we provide recommendations for converting low-Mach number codes to this equation set.

  15. Greatly Increasing Trapped Ion Populations for Mobility Separations Using Traveling Waves in Structures for Lossless Ion Manipulations

    SciTech Connect

    Deng, Liulin; Ibrahim, Yehia M.; Garimella, Sandilya V. B.; Webb, Ian K.; Hamid, Ahmed M.; Norheim, Randolph V.; Prost, Spencer A.; Sandoval, Jeremy A.; Baker, Erin S.; Smith, Richard D.

    2016-10-18

    The initial use of traveling waves (TW) for ion mobility (IM) separations using a structures for lossless ion manipulations (SLIM) employed an ion funnel trap (IFT) to accumulate ions from a continuous electrospray ionization source, and limited to injected ion populations of ~106 charges due to the onset of space charge effects in the trapping region. Additional limitations arise due to the loss of resolution for the injection of ions over longer periods (e.g. in extended pulses). In this work a new SLIM ‘flat funnel’ (FF) module has been developed and demonstrated to enable the accumulation of much larger ion populations and their injection for IM separations. Ion current measurements indicate a capacity of ~3.2×108 charges for the extended trapping volume, over an order of magnitude greater than the IFT. The orthogonal ion injection into a funnel shaped separation region can greatly reduce space charge effects during the initial IM separation stage, and the gradually reduced width of the path allows the ion packet to be increasingly compressed in the lateral dimension as the separation progresses, allowing e.g. efficient transmission through conductance limits or compatibility with subsequent ion manipulations. This work examined the TW, RF, and DC confining field SLIM parameters involved in ion accumulation, injection, transmission and separation in the FF IM module using both direct ion current and MS measurements. Wide m/z range ion transmission is demonstrated, along with significant increases in signal to noise (S/N) ratios due to the larger ion populations injected. Additionally, we observed a reduction in the chemical background, which was attributed to more efficient desolvation of solvent related clusters over the extended ion accumulation periods. The TW SLIM FF IM module is anticipated to be especially effective as a front end for long path SLIM IM separation modules.

  16. Solitary and freak waves in a dusty plasma with negative ions

    SciTech Connect

    Abdelsalam, U. M.; Moslem, W. M.; Khater, A. H.; Shukla, P. K.

    2011-09-15

    It is shown that solitary and freak waves can propagate in a dusty plasma composed of positive and negative ions, as well as nonextensive electrons. The evolution of the solitary waves is described by the Korteweg-de Vries (KdV) equation. However, when the frequency of the carrier wave is much smaller than the ion plasma frequency then the KdV equation is also used to study the nonlinear evolution of modulationally unstable modified ion-acoustic wavepackets through the derivation of the nonlinear Schroedinger (NLS) equation. In order to show that the characteristics of the solitary and freak waves are influenced by the plasma parameters, the relevant numerical analysis of the appropriate nonlinear solutions is presented. The relevance of the present investigation to nonlinear waves in astrophysical plasma environments is discussed.

  17. The nonlinear evolution of driven nonlinear ion acoustic waves with kinetic electrons

    NASA Astrophysics Data System (ADS)

    Berger, Richard; Brunner, Stephan; Valeo, Ernest; Divol, Laurent; Still, Charles

    2006-10-01

    The stimulated Brillouin scattering (SBS) of laser light from hot plasma drives ion acoustic waves to large amplitudes particularly if the phase velocity is much greater than the ion thermal velocity for all ion species, that is, ZTe/Ti >>1 where Z is the charge state of the ion, and Te and Ti are the electron and ion temperatures. In fluid simulations of the SBS from CO2 and Krypton plasmas, ad hoc limits on the amplitude of the driven ion waves were required to match the measured reflectivity. Because ZTe/Ti >>1, ion kinetics are unlikely to play a role in the saturation of ion waves. Here, we study the effect of electron trapping which produces a positive frequency shift in quantitative agreement with theory (see abstract by S. Brunner et al., this meeting) and the role of electron kinetics on the decay instability of the driven ion wave. Further, we apply these results to modeling of experiments where ZTe/Ti >>1 [e.g., Glenzer et al., PRL 86, 2565 (2001), L. Divol, et al., Physics of Plasmas 10, 1822 (2003)].

  18. Mid-frequency sound propagation through internal waves at short range with synoptic oceanographic observations.

    PubMed

    Rouseff, Daniel; Tang, Dajun; Williams, Kevin L; Wang, Zhongkang; Moum, James N

    2008-09-01

    Preliminary results are presented from an analysis of mid-frequency acoustic transmission data collected at range 550 m during the Shallow Water 2006 Experiment. The acoustic data were collected on a vertical array immediately before, during, and after the passage of a nonlinear internal wave on 18 August, 2006. Using oceanographic data collected at a nearby location, a plane-wave model for the nonlinear internal wave's position as a function of time is developed. Experimental results show a new acoustic path is generated as the internal wave passes above the acoustic source.

  19. Space-Borne Radio-Sounding Investigations Facilitated by the Virtual Wave Observatory (VWO)

    NASA Technical Reports Server (NTRS)

    Benson, Robert F.; Fung, Shing F.; Bilitza,Dieter; Garcia, Leonard N.; Shao, Xi; Galkin, Ivan A.

    2011-01-01

    The goal of the Virtual Wave Observatory (VWO) is to provide userfriendly access to heliophysics wave data. While the VWO initially emphasized the vast quantity of wave data obtained from passive receivers, the VWO infrastructure can also be used to access active sounder data sets. Here we use examples from some half-million Alouette-2, ISIS-1, and ISIS-2 digital topside-sounder ionograms to demonstrate the desirability of such access to the actual ionograms for investigations of both natural and sounder-stimulated plasma-wave phenomena. By this demonstration, we wish to encourage investigators to make other valuable space-borne sounder data sets accessible via the VWO.

  20. Dust ion-acoustic solitary and shock waves due to dust charge fluctuation with vortexlike electrons

    SciTech Connect

    Duha, S. S.; Anowar, M. G. M.; Mamun, A. A.

    2010-10-15

    A rigorous theoretical investigation has been made of the dust ion-acoustic (DIA) solitary and shock waves in an unmagnetized dusty plasma (containing vortexlike electrons, mobile ions, and charge fluctuating static dust) by reductive perturbation method. The effects of dust grain charge fluctuation and vortexlike (trapped) electron are found to modify the properties of the DIA solitary and shock waves significantly. The implications of these results for some space and astrophysical dusty plasma systems, especially planetary ring systems, are briefly mentioned.

  1. Propagation and oblique collision of ion-acoustic solitary waves in a magnetized dusty electronegative plasma

    SciTech Connect

    El-Labany, S. K.; Behery, E. E.; El-Shamy, E. F.

    2013-12-15

    The propagation and oblique collision of ion-acoustic (IA) solitary waves in a magnetized dusty electronegative plasma consisting of cold mobile positive ions, Boltzmann negative ions, Boltzmann electrons, and stationary positive/negative dust particles are studied. The extended Poincaré-Lighthill-Kuo perturbation method is employed to derive the Korteweg-de Vries equations and the corresponding expressions for the phase shifts after collision between two IA solitary waves. It turns out that the angle of collision, the temperature and density of negative ions, and the dust density of opposite polarity have reasonable effects on the phase shift. Clearly, the numerical results demonstrated that the IA solitary waves are delayed after the oblique collision. The current finding of this work is applicable in many plasma environments having negative ion species, such as D- and F-regions of the Earth's ionosphere and some laboratory plasma experiments.

  2. The Sound of Science

    ERIC Educational Resources Information Center

    Merwade, Venkatesh; Eichinger, David; Harriger, Bradley; Doherty, Erin; Habben, Ryan

    2014-01-01

    While the science of sound can be taught by explaining the concept of sound waves and vibrations, the authors of this article focused their efforts on creating a more engaging way to teach the science of sound--through engineering design. In this article they share the experience of teaching sound to third graders through an engineering challenge…

  3. Numerical Simulation of Waves Driven by Plasma Currents Generated by Low-Frequency Alfven Waves in a Multi-Ion Plasma

    NASA Technical Reports Server (NTRS)

    Singh, Nagendra; Khazanov, George

    2003-01-01

    When multi-ion plasma consisting of heavy and light ions is permeated by a lowfrequency Alfien (LFA) wave, the EXB and the polarization drifts of the different ion species and the electrons could be quite different. The relative drifts between the charged-particle species drive waves, which energize the plasma. Using 2.5-D particle-in-cell simulations, we study this process of wave generation and its nonlinear consequences in terms of acceleration and heating plasma. Specifically we study the situation for LFA wave frequency being lower than the heavyion cyclotron frequency in a multi-ion plasma. We impose such a wave to the plasma assuming that its wavelength is much larger than that of the waves generated by the relative drifts. For better understanding, the LFA-wave driven simulations are augmented by those driven by initialized ion beams.

  4. IONS-06 Ozone Profiles in the Rural-Urban Transition at Mexico City in March 2006: Mixture of Pollution and UT/LS Waves

    NASA Astrophysics Data System (ADS)

    Thompson, A. M.; Long, R. B.; Miller, S. K.; Yorks, J. E.; Madigan, M. J.; Witte, J. C.; Kucsera, T. L.; Lefer, B.; Morris, G. A.

    2006-12-01

    We have used ozone profile data from soundings for better interpretation of atmospheric chemistry and dynamics at the urban-non-urban interface. Notably soundings have been taken during regional field campaigns like INTEX-NA (Intercontinental Transport Experiment - North America, 2004) and the 2006 Milagro/MIRAGE-Mex (Megacity Impacts of Regional and Global Environments)/ INTEX-B. IONS (INTEX Ozonesonde Network Study) is a network for studying the vertical structure and long-range transport of ozone and tropospheric water vapor during the INTEX experiments. In IONS-04, the urban-non-urban transition, was targeted at Beltsville, Maryland, a wooded suburban Washington DC site, and Narragansett, a coastal region downwind of New York City. From 5 to 20 March 2006, during IONS-06, ozone soundings were made over the Milagro T1 site (Tecamac, 19N, 99W), at the urban-rural interface, about 80 km NE of Mexico City. Simultaneous soundings were made over Houston, TX, 30N, 95W, approximately 1000 km to the northeast. Day-to-day variations in tropospheric ozone at T1 are explained by regional meteorology and emissions. Pollution accumulation at T1 was most noticeable during a stagnation period early in March, with winds from Mexico City. Downwind of T1, Houston was affected on 10 March 2006. In addition to pollution impacts, ozone variations throughout the troposphere and lower stratosphere over T1 were associated with equatorial Gravity waves. IONS-06 images for Mexico City/Tecamac, Houston, and those for other March 2006 data are viewable at: http://croc.gsfc.nasa.gov/intexb/ions06.

  5. Ion Cyclotron Waves Observed at Galileo's Io Encounter: Implications for Neutral Cloud Distribution

    NASA Astrophysics Data System (ADS)

    Warnecke, J.; Walker, R. J.; Russell, C. T.; Kivelson, M. G.; Khurana, K. K.

    1996-09-01

    At Galileo's Io encounter on December 7, 1995, the magnetic field experiment detected large-amplitude, highly coherent waves near the SO(+_2) and SO(+) gyro-frequencies. On the inbound leg of the flyby, these waves were detected starting about 18 RIO from Io. Their power spectral density decreased as 1/r(3) . On the outbound leg, the waves decayed more rapidly. The waves are believed to be caused by the ionization and pickup of particles originating from Io by the corotating magnetospheric plasma. The presence of wave power near the molecular ion gyro-frequencies reveals that neutral molecules survive intact over a surprisingly large range of distances from Io.

  6. Observation of fast-ion Doppler-shifted cyclotron resonance with shear Alfven waves

    SciTech Connect

    Zhang Yang; Heidbrink, W. W.; Boehmer, H.; McWilliams, R.; Vincena, S.; Carter, T. A.; Gekelman, W.; Leneman, D.; Pribyl, P.

    2008-10-15

    The Doppler-shifted cyclotron resonance ({omega}-k{sub z}v{sub z}={omega}{sub f}) between fast ions and shear Alfven waves is experimentally investigated ({omega}, wave frequency; k{sub z}, axial wavenumber; v{sub z}, fast-ion axial speed; {omega}{sub f}, fast-ion cyclotron frequency). A test particle beam of fast ions is launched by a Li{sup +} source in the helium plasma of the LArge Plasma Device (LAPD) [W. Gekelman, H. Pfister, Z. Lucky, J. Bamber, D. Leneman, and J. Maggs, Rev. Sci. Instrum. 62, 2875 (1991)], with shear Alfven waves (SAW) (amplitude {delta} B/B up to 1%) launched by a loop antenna. A collimated fast-ion energy analyzer measures the nonclassical spreading of the beam, which is proportional to the resonance with the wave. A resonance spectrum is observed by launching SAWs at 0.3-0.8{omega}{sub ci}. Both the magnitude and frequency dependence of the beam-spreading are in agreement with the theoretical prediction using a Monte Carlo Lorentz code that launches fast ions with an initial spread in real/velocity space and random phases relative to the wave. Measured wave magnetic field data are used in the simulation.

  7. Observation of multiple mechanisms for stimulating ion waves in ignition scale plasmas. Revision 1

    SciTech Connect

    Kirkwood, R.K.; MacGowan, B.J.; Montgomery, D.S.

    1997-03-03

    The laser and plasma conditions expected in ignition experiments using indirect drive inertial confinement have been studied experimentally. It has been shown that there are at least three ways in which ion waves can be stimulated in these plasmas and have significant effect on the energy balance and distribution in the target. First ion waves can be stimulated by a single laser beam by the process of Stimulated Brillouin Scattering (SBS) in which an ion acoustic and a scattered electromagnetic wave grow from noise. Second, in a plasma where more than one beam intersect, ion waves can Lie excited at the `beat` frequency and wave number of the intersecting beams,, causing the side scatter instability to be seeded, and substantial energy to be transferred between the beams [R. K. Kirkwood et. al. Phys. Rev. Lett. 76, 2065 (1996)]. And third, ion waves may be stimulated by the decay of electron plasma waves produced by Stimulated Raman Scattering (SRS), thereby inhibiting the SRS process [R. K. Kirkwood et. al. Phys. Rev. Lett. 77, 2706 (1996)].

  8. Transverse acceleration of oxygen ions by electromagnetic ion cyclotron resonance with broad band left-hand polarized waves

    NASA Technical Reports Server (NTRS)

    Chang, T.; Crew, G. B.; Hershkowitz, N.; Jasperse, J. R.; Retterer, J. M.

    1986-01-01

    Central plasma sheet (CPS) ion conics are oxygen-dominated, with peak energies ranging from tens to hundreds of eV centered around pitch-angles between 115 and 130 degrees. Because of the lack of correlation between the CPS conics and the observed currents and/or electron beam-like structures, it is not likely that all of these conics are generated by interactions with electrostatic ion cyclotron waves or lower hybrid waves. Instead, it is suggested that the observed intense broad band electric field fluctuations in the frequency range between 0 and 100 Hz can be responsible for the transverse energization of the ions through cyclotron resonance heating with the left-hand polarized electromagnetic waves. This process is much more efficient for heating the oxygen ions than hydrogen ions, thus providing a plausible explanation of the oxygen dominance in CPS conics. Simple algebraic expressions are given from which estimates of conic energy and pitch angle can be easily calculated. This suggested mechanism can also provide some preheating of the oxygen ions in the boundary plasma sheet (BPS) where discrete aurorae form.

  9. Stability of ion acoustic nonlinear waves and solitons in magnetized plasmas

    NASA Astrophysics Data System (ADS)

    Goldstein, Piotr; Infeld, Eryk

    2016-12-01

    Early results concerning the shape and stability of ion acoustic waves are generalized to propagation at an angle to the magnetic field lines. Each wave has a critical angle for stability. Known soliton results are recovered as special cases. A historical overview of the problem concludes the paper.

  10. Effects of external magnetic field on oblique propagation of ion acoustic cnoidal wave in nonextensive plasma

    NASA Astrophysics Data System (ADS)

    Farhad Kiyaei, Forough; Dorranian, Davoud

    2017-01-01

    Effects of the obliqueness and the strength of external magnetic field on the ion acoustic (IA) cnoidal wave in a nonextensive plasma are investigated. The reductive perturbation method is employed to derive the corresponding KdV equation for the IA wave. Sagdeev potential is extracted, and the condition of generation of IA waves in the form of cnoidal waves or solitons is discussed in detail. In this work, the domain of allowable values of nonextensivity parameter q for generation of the IA cnoidal wave in the plasma medium is considered. The results show that only the compressive IA wave may generate and propagate in the plasma medium. Increasing the strength of external magnetic field will increase the frequency of the wave and decrease its amplitude, while increasing the angle of propagation will decrease the frequency of the wave and increase its amplitude.

  11. Anomalous electron-ion energy coupling in electron drift wave turbulence

    NASA Astrophysics Data System (ADS)

    Zhao, Lei

    Turbulence is a ubiquitous phenomenon in nature, and it is well known that turbulence couples energy input to dissipation by cascade processes. Plasma turbulence play a critical role in tokamak confinement. Magnetized plasma turbulence is quasi 2D, anisotropic, wave like and two fluid (i.e. electrons and ions) in structure. Thus, weakly collisional plasma turbulence can mediate electron and ion energy transfer. The issue of anomalous electron and ion energy coupling is particularly important for low collisionality, electron heated plasmas, such as ITER. In this work, we reconsider the classic problem of turbulent heating and energy transfer pathways in drift wave turbulence. The total turbulent heating, composed of quasilinear electron cooling, quasilinear ion heating, nonlinear ion heating and zonal flow frictional heating, is analyzed. In Chapter 2, the electron and ion energy exchange via linear wave and particle resonance will be computed. To address net heating, we show the turbulent heating in an annulus arises due to a wave energy flux differential across this region. We show this net heating is proportional to the Reynolds work on the zonal flow. Zonal flow friction heats ions, thus the turbulence and zonal flow interaction enters as an important energy transfer channel. Since zonal flows are nonlinearly generated, it follows that we should apply weak turbulence theory to calculate the nonlinear ion turbulent heating via the virtual mode resonance in the electron drift wave turbulence, which will be discussed in Chapter 3. We defines a new collisionless turbulent energy transfer channel through nonlinear Landau damping in the electron and ion energy coupling process. The result shows that nonlinear ion heating can exceed quasilinear ion heating, so that nonlinear heating becomes the principal collisionless wave energy dissipation channel in electron drift wave turbulence. This follows since the beat mode resonates with the bulk of the ion distribution, in

  12. Probing the shear-band formation in granular media with sound waves

    NASA Astrophysics Data System (ADS)

    Khidas, Y.; Jia, X.

    2012-05-01

    We investigate the mechanical responses of dense granular materials, using a direct shear box combined with simultaneous acoustic measurements. Measured shear wave speeds evidence the structural change of the material under shear, from the jammed state to the flowing state. There is a clear acoustic signature when the shear band is formed. Subjected to cyclic shear, both shear stress and wave speed show the strong hysteretic dependence on the shear strain, likely associated with the geometry change in the packing structure. Moreover, the correlation function of configuration-specific multiply scattered waves reveals an intermittent behavior before the failure of material.

  13. Dust ion-acoustic shock waves in an adiabatic dusty plasma

    SciTech Connect

    Rahman, Armina; Sayed, Fatema; Mamun, A. A.

    2007-03-15

    The properties of dust ion-acoustic shock waves in an unmagnetized dusty plasma, whose constituents are adiabatic ion fluid, Boltzmann electrons, and static dust, are investigated by employing the reductive perturbation method. The Burgers equation is derived and its stationary analytical solution is numerically analyzed. It has been found that both the amplitude and the width decrease with the increase of the ion-fluid temperature. The implications of our results in space and laboratory dusty plasmas are briefly discussed.

  14. Edge Ion Heating by Launched High Harmonic Fast Waves in NSTX

    SciTech Connect

    T.M. Biewer; R.E. Bell; S.J. Diem; C.K. Phillips; J.R. Wilson; P.M. Ryan

    2004-12-01

    A new spectroscopic diagnostic on the National Spherical Torus Experiment (NSTX) measures the velocity distribution of ions in the plasma edge simultaneously along both poloidal and toroidal views. An anisotropic ion temperature is measured during high-power high harmonic fast wave (HHFW) radio-frequency (rf) heating in helium plasmas, with the poloidal ion temperature roughly twice the toroidal ion temperature. Moreover, the measured spectral distribution suggests that two populations of ions are present and have temperatures of typically 500 eV and 50 eV with rotation velocities of -50 km/s and -10 km/s, respectively (predominantly perpendicular to the local magnetic field). This bi-modal distribution is observed in both the toroidal and poloidal views (for both He{sup +} and C{sup 2+} ions), and is well correlated with the period of rf power application to the plasma. The temperature of the hot component is observed to increase with the applied rf power, which was scanned between 0 and 4.3 MW . The 30 MHz HHFW launched by the NSTX antenna is expected and observed to heat core electrons, but plasma ions do not resonate with the launched wave, which is typically at >10th harmonic of the ion cyclotron frequency in the region of observation. A likely ion heating mechanism is parametric decay of the launched HHFW into an Ion Bernstein Wave (IBW). The presence of the IBW in NSTX plasmas during HHFW application has been directly confirmed with probe measurements. IBW heating occurs in the perpendicular ion distribution, consistent with the toroidal and poloidal observations. Calculations of IBW propagation indicate that multiple waves could be created in the parametric decay process, and that most of the IBW power would be absorbed in the outer 10 to 20 cm of the plasma, predominantly on fully stripped ions. These predictions are in qualitative agreement with the observations, and must be accounted for when calculating the energy budget of the plasma.

  15. A comprehensive analysis of ion cyclotron waves in the equatorial magnetosphere of Saturn

    NASA Astrophysics Data System (ADS)

    Meeks, Zachary; Simon, Sven; Kabanovic, Slawa

    2016-09-01

    We present a comprehensive analysis of ion cyclotron waves in the equatorial magnetosphere of Saturn, considering all magnetic field data collected during the Cassini era (totaling to over 4 years of data from the equatorial plane). This dataset includes eight targeted flybys of Enceladus, three targeted flybys of Dione, and three targeted flybys of Rhea. Because all remaining orbits of Cassini are high-inclination, our study provides the complete map of ion cyclotron waves in Saturn's equatorial magnetosphere during the Cassini era. We provide catalogs of the radial and longitudinal dependencies of the occurrence rate and amplitude of the ion cyclotron fundamental and first harmonic wave modes. The fundamental wave mode is omnipresent between the orbits of Enceladus and Dione and evenly distributed across all Local Times. The occurrence rate of the fundamental mode displays a Fermi-Dirac-like profile with respect to radial distance from Saturn. Detection of the first harmonic mode is a rare event occurring in only 0.49% of measurements taken and always in conjunction with the fundamental mode. We also search for a dependency of the ion cyclotron wave field on the orbital positions of the icy moons Enceladus, Dione, and Rhea. On magnetospheric length scales, the wave field is independent of the moons' orbital positions. For Enceladus, we analyze wave amplitude profiles of seven close flybys (E9, E12, E13, E14, E17, E18, and E19), which occurred during the studied trajectory segments, to look for any local effects of Enceladan plume variability on the wave field. We find that even in the close vicinity of Enceladus, the wave amplitudes display no discernible dependency on Enceladus' angular distance to its orbital apocenter. Thus, the correlation between plume activity and angular distance to apocenter proposed by Hedman et al. (2013) does not leave a clearly distinguishable imprint in the ion cyclotron wave field.

  16. Oblique propagation of dust ion-acoustic solitary waves in a magnetized dusty pair-ion plasma

    NASA Astrophysics Data System (ADS)

    Misra, A. P.; Barman, Arnab

    2014-07-01

    We investigate the propagation characteristics of electrostatic waves in a magnetized pair-ion plasma with immobile charged dusts. It is shown that obliquely propagating (OP) low-frequency (in comparison with the negative-ion cyclotron frequency) long-wavelength "slow" and "fast" modes can propagate, respectively, as dust ion-acoustic (DIA) and dust ion-cyclotron (DIC)-like waves. The properties of these modes are studied with the effects of obliqueness of propagation (θ), the static magnetic field, the ratios of the negative to positive ion masses (m), and temperatures (T) as well as the dust to negative-ion number density ratio (δ). Using the standard reductive perturbation technique, we derive a Korteweg-de Vries (KdV) equation which governs the evolution of small-amplitude OP DIA waves. It is found that the KdV equation admits only rarefactive solitons in plasmas with m well below its critical value mc (≫ 1) which typically depends on T and δ. It is shown that the nonlinear coefficient of the KdV equation vanishes at m = mc, i.e., for plasmas with much heavier negative ions, and the evolution of the DIA waves is then described by a modified KdV (mKdV) equation. The latter is shown to have only compressive soliton solution. The properties of both the KdV and mKdV solitons are studied with the system parameters as above, and possible applications of our results to laboratory and space plasmas are briefly discussed.

  17. Oblique propagation of dust ion-acoustic solitary waves in a magnetized dusty pair-ion plasma

    SciTech Connect

    Misra, A. P. E-mail: apmisra@gmail.com; Barman, Arnab

    2014-07-15

    We investigate the propagation characteristics of electrostatic waves in a magnetized pair-ion plasma with immobile charged dusts. It is shown that obliquely propagating (OP) low-frequency (in comparison with the negative-ion cyclotron frequency) long-wavelength “slow” and “fast” modes can propagate, respectively, as dust ion-acoustic (DIA) and dust ion-cyclotron (DIC)-like waves. The properties of these modes are studied with the effects of obliqueness of propagation (θ), the static magnetic field, the ratios of the negative to positive ion masses (m), and temperatures (T) as well as the dust to negative-ion number density ratio (δ). Using the standard reductive perturbation technique, we derive a Korteweg-de Vries (KdV) equation which governs the evolution of small-amplitude OP DIA waves. It is found that the KdV equation admits only rarefactive solitons in plasmas with m well below its critical value m{sub c} (≫ 1) which typically depends on T and δ. It is shown that the nonlinear coefficient of the KdV equation vanishes at m = m{sub c}, i.e., for plasmas with much heavier negative ions, and the evolution of the DIA waves is then described by a modified KdV (mKdV) equation. The latter is shown to have only compressive soliton solution. The properties of both the KdV and mKdV solitons are studied with the system parameters as above, and possible applications of our results to laboratory and space plasmas are briefly discussed.

  18. Comparison of magnetosonic wave and water group ion energy densities at Comet Giacobini-Zinner

    NASA Technical Reports Server (NTRS)

    Staines, K.; Balogh, A.; Cowley, S. W. H.; Forster, P. M. De F.; Hynds, R. J.; Yates, T. S.; Sanderson, T. R.; Wenzel, K.-P.; Tsurutani, B. T.

    1991-01-01

    Measurements of the Comet Giacobini-Zinner (GZ) are presented to determine to what extent wave-particle scattering redistributed the initial pick-up energy of the ion population. Also examined is the difference between the ion thermal energy and the energy in the magnetic fields of the waves. In spite of uncertainty of about a factor of 2 noted in the pick-up and mass-loaded regions, it is shown that less than approximately 50 percent of the pick-up energy is converted into wave magnetic energy in the inbound pick-up region.

  19. Charging-delay induced dust acoustic collisionless shock wave: Roles of negative ions

    SciTech Connect

    Ghosh, Samiran; Bharuthram, R.; Khan, Manoranjan; Gupta, M. R.

    2006-11-15

    The effects of charging-delay and negative ions on nonlinear dust acoustic waves are investigated. It has been found that the charging-delay induced anomalous dissipation causes generation of dust acoustic collisionless shock waves in an electronegative dusty plasma. The small but finite amplitude wave is governed by a Korteweg-de Vries Burger equation in which the Burger term arises due to the charging-delay. Numerical investigations reveal that the charging-delay induced dissipation and shock strength decreases (increases) with the increase of negative ion concentration (temperature)

  20. Dust-ion acoustic freak wave propagation in a nonthermal mesospheric dusty plasma

    NASA Astrophysics Data System (ADS)

    El-Labany, S. K.; El-Shewy, E. K.; Abd El-Razek, H. N.; El-Rahman, A. A.

    2017-03-01

    Nonlinear properties of dust-ion acoustic freak waves have been studied in homogeneous unmagnetized dusty plasmas consisting of ions, nonthermal fast electrons, and positive and negative dust grains. By using derivative expansion method under the assumption of strongly dispersive medium, the basic equations are reduced to nonlinear Schrödinger equation (NLSE). One of NLSE solutions in the unstable region is the rational one which is responsible for creation of the freak waves. The dependence of the freak wave profile on the dust grain charge, carrier wavenumber, and energetic nonthermal electron population is discussed.

  1. Coronal Alfven waves detected by radio sounding during the solar occultations of the HELIOS spacecraft

    NASA Astrophysics Data System (ADS)

    Bird, M. K.; Volland, H.; Efimov, A. I.; Levy, G. S.; Seidel, B. L.; Stelzried, C. T.

    The two Helios spacecraft underwent regular solar occultations during their extended missions from Dec 1974-Feb 1986 (Helios 1) and Jan 1976-Mar 1980 (Helios 2) thereby providing many opportunities for radio propagation experiments in the solar corona. On certain rare occasions over the course of these investigations, Faraday rotation measurements of the linearly polarized Helios signals could be recorded simultaneously at two widely-spaced ground stations. Many of these two-station measurement intervals display clear evidence of wave-like structures with quasi-periods of the order of a few minutes to a few hours. These structures are attributed to coronal Alfven waves. The radial propagation direction and velocity of these waves are estimated from a cross-correlation analysis of the data between the two stations. The majority of the waves appear to propagate away from the Sun, but about 30 percent of the cases indicate a propagation direction toward the Sun.

  2. Stimulated Scattering of Light from Ion Acoustic Waves in Collisional Multi-species Plasma.

    NASA Astrophysics Data System (ADS)

    Berger, Richard; Valeo, Ernest

    2003-10-01

    The dispersion properties of ion acoustic waves (IAW) are sensitive to the strength of ion-ion collisions,especially in multi-species plasma in which the different species have differing charge-to-mass ratios(Bychenkov et al., PRE 51, 1400 (1995)). Here, we consider the modification of the frequency and damping of the fast and slow acoustic modes in a plasma composed of light (low Z) and heavy (high Z) ions. In the fluid limit, kλ_lh <<1, the friction between the two species causes the damping whereas, in the collisionless limit, Landau damping of the light ions provides the dissipation. Collisions between light and heavy ions also affect the nonlinear response(P. W. Rambo, S. C. Wilks, and W. L. Kruer, Phys. Rev. Lett. 79), 83 (1997).. We examine the effects of collisions on the linear evolution of ion waves driven by the ponderomotive force of two light waves within the context of linear parametric instability theory. The simulation of the nonlinear evolution is done with a δ f model that evolves the background(E. J. Valeo and S. Brunner, Bull. Am. Phys. Soc. 46), QP1.137 (2001)., and includes the effects of collisions of light on heavy ions within the Lorentz model. The calculated effect of a small number of high Z ions on SBS in low Z plasmas will be compared with recent experimental results(Suter et al.,private communication). l

  3. Argon–oxygen dc magnetron discharge plasma probed with ion acoustic waves

    SciTech Connect

    Saikia, Partha Saikia, Bipul Kumar; Goswami, Kalyan Sindhu; Phukan, Arindam

    2014-05-15

    The precise determination of the relative concentration of negative ions is very important for the optimization of magnetron sputtering processes, especially for those undertaken in a multicomponent background produced by adding electronegative gases, such as oxygen, to the discharge. The temporal behavior of an ion acoustic wave excited from a stainless steel grid inside the plasma chamber is used to determine the relative negative ion concentration in the magnetron discharge plasma. The phase velocity of the ion acoustic wave in the presence of negative ions is found to be faster than in a pure argon plasma, and the phase velocity increases with the oxygen partial pressure. Optical emission spectroscopy further confirms the increase in the oxygen negative ion density, along with a decrease in the argon positive ion density under the same discharge conditions. The relative negative ion concentration values measured by ion acoustic waves are compared with those measured by a single Langmuir probe, and a similarity in the results obtained by both techniques is observed.

  4. Dynamic acoustics for the STAR-100. [computer algorithms for time dependent sound waves in jet

    NASA Technical Reports Server (NTRS)

    Bayliss, A.; Turkel, E.

    1979-01-01

    An algorithm is described to compute time dependent acoustic waves in a jet. The method differs from previous methods in that no harmonic time dependence is assumed, thus permitting the study of nonharmonic acoustical behavior. Large grids are required to resolve the acoustic waves. Since the problem is nonstiff, explicit high order schemes can be used. These have been adapted to the STAR-100 with great efficiencies and permitted the efficient solution of problems which would not be feasible on a scalar machine.

  5. Investigation of electrostatic waves in the ion cyclotron range of frequencies in L-4 and ACT-1

    SciTech Connect

    Ono, Masayuki.

    1993-05-01

    Electrostatic waves in the ion cyclotron range of frequencies (ICRF) were studied in the Princeton L-4 and ACT-1 devices for approximately ten years, from 1975 to 1985. The investigation began in the L-4 linear device, looking for the parametric excitation of electrostatic ion cyclotron waves in multi-ion-species plasmas. In addition, this investigation verified multi-ion-species effects on the electrostatic ion cyclotron wave dispersion religion including the ion-ion hybrid resonance. Finite-Larmor-radius modification of the wave dispersion relation was also observed, even for ion temperatures of T[sub i] [approx] 1/40 eV. Taking advantage of the relatively high field and long device length of L-4, the existence of the cold electrostatic ion cyclotron wave (CES ICW) was verified. With the arrival of the ACT-1 toroidal device, finite-Larmor-radius (FLR) waves were studied in a relatively collisionless warm-ion hydrogen plasma. Detailed investigations of ion Bernstein waves (IBW) included the verification of mode-transformation in their launching, their wave propagation characteristics, their absorption, and the resulting ion heating. This basic physics activity played a crucial role in developing a new reactor heating concept termed ion Bernstein wave heating. Experimental research in the lower hybrid frequency range confirmed the existence of FLR effects near the lower hybrid resonance, predicted by Stix in 1965. In a neon plasma with a carefully placed phased wave exciter, the neutralized ion Bernstein wave was observed for the first time. Using a fastwave ICRF antenna, two parasitic excitation processes for IBW -- parametric instability and density-gradient-driven excitation -- were also discovered. In the concluding section of this paper, a possible application of externally launched electrostatic waves is suggested for helium ash removal from fusion reactor plasmas.

  6. Investigation of electrostatic waves in the ion cyclotron range of frequencies in L-4 and ACT-1

    SciTech Connect

    Ono, Masayuki

    1993-05-01

    Electrostatic waves in the ion cyclotron range of frequencies (ICRF) were studied in the Princeton L-4 and ACT-1 devices for approximately ten years, from 1975 to 1985. The investigation began in the L-4 linear device, looking for the parametric excitation of electrostatic ion cyclotron waves in multi-ion-species plasmas. In addition, this investigation verified multi-ion-species effects on the electrostatic ion cyclotron wave dispersion religion including the ion-ion hybrid resonance. Finite-Larmor-radius modification of the wave dispersion relation was also observed, even for ion temperatures of T{sub i} {approx} 1/40 eV. Taking advantage of the relatively high field and long device length of L-4, the existence of the cold electrostatic ion cyclotron wave (CES ICW) was verified. With the arrival of the ACT-1 toroidal device, finite-Larmor-radius (FLR) waves were studied in a relatively collisionless warm-ion hydrogen plasma. Detailed investigations of ion Bernstein waves (IBW) included the verification of mode-transformation in their launching, their wave propagation characteristics, their absorption, and the resulting ion heating. This basic physics activity played a crucial role in developing a new reactor heating concept termed ion Bernstein wave heating. Experimental research in the lower hybrid frequency range confirmed the existence of FLR effects near the lower hybrid resonance, predicted by Stix in 1965. In a neon plasma with a carefully placed phased wave exciter, the neutralized ion Bernstein wave was observed for the first time. Using a fastwave ICRF antenna, two parasitic excitation processes for IBW -- parametric instability and density-gradient-driven excitation -- were also discovered. In the concluding section of this paper, a possible application of externally launched electrostatic waves is suggested for helium ash removal from fusion reactor plasmas.

  7. Fluid simulation of dispersive and nondispersive ion acoustic waves in the presence of superthermal electrons

    NASA Astrophysics Data System (ADS)

    Lotekar, Ajay; Kakad, Amar; Kakad, Bharati

    2016-10-01

    One-dimensional fluid simulation is performed for the unmagnetized plasma consisting of cold fluid ions and superthermal electrons. Such a plasma system supports the generation of ion acoustic (IA) waves. A standard Gaussian type perturbation is used in both electron and ion equilibrium densities to excite the IA waves. The evolutionary profiles of the IA waves are obtained by varying the superthermal index and the amplitude of the initial perturbation. This simulation demonstrates that the amplitude of the initial perturbation and the superthermal index play an important role in determining the time evolution and the characteristics of the generated IA waves. The initial density perturbation in the system creates charge separation that drives the finite electrostatic potential in the system. This electrostatic potential later evolves into the dispersive and nondispersive IA waves in the simulation system. The density perturbation with the amplitude smaller than 10% of the equilibrium plasma density evolves into the dispersive IA waves, whereas larger density perturbations evolve into both dispersive and nondispersive IA waves for lower and higher superthermal index. The dispersive IA waves are the IA oscillations that propagate with constant ion plasma frequency, whereas the nondispersive IA waves are the IA solitary pulses (termed as IA solitons in the stability region) that propagate with the constant wave speed. The characteristics of the stable nondispersive IA solitons are found to be consistent with the nonlinear fluid theory. To the best of our knowledge, this is the first fluid simulation study that has considered the superthermal distributions for the plasma species to model the electrostatic solitary waves.

  8. Fast damping of poloidal Alfven waves by bounce-resonant ions: observations and modeling

    NASA Astrophysics Data System (ADS)

    Wang, C.; Rankin, R.; Sydorenko, D.; Zong, Q.

    2015-12-01

    Interplanetary shocks and solar wind dynamic pressure variations can excite intense ultra-low-frequency (ULF) waves in the inner magnetosphere. An analysis of two interplanetary shocks observed by Cluster on 7 November 2004 and 30 August 2001 shows that the poloidal waves excited in these events are damped away rapidly in tens of minutes. This damping is the result of wave-particle interactions involving H+ and O+ ions with energies in the range of several to a few tens of keV [Wang et al., J. Geophys. Res., 2015]. Damping is found to be more effective in the plasmasphere boundary layer due to the relatively higher proportion of Landau resonant ions that exists in that region. In the November 2004 shock event it has been suggested that energy-dispersed ions observed travelling parallel and anti-parallel direction to the geomagnetic field immediately after the shockare locally accelerated rather than originating from Earth's ionosphere. We use test-particle simulations to show that adiabatic advection of the particle differential flux caused bydrift-bounce-resonance with ULF waves is responsible for the energy-dispersed ions observed in these events. In the simulations,Liouville's theorem is used to reconstruct the iondistribution function and differential flux in a model dipole magnetosphere.It is shown that flux modulations of H and O ions can be reproduced when test-particle ions are advanced in the electric fields of the 3D ULF wave model we have developed.

  9. Treatment of ion-atom collisions using a partial-wave expansion of the projectile wavefunction

    SciTech Connect

    Foster, M; Colgan, J; Wong, T G; Madison, D H

    2008-01-01

    We present calculations of ion-atom collisions using a partial-wave expansion of the projectile wavefunction. Most calculations of ion-atom collisions have typically used classical or plane-wave approximations for the projectile wavefunction, since partial-wave expansions are expected to require prohibitively large numbers of terms to converge scattering quantities. Here we show that such calculations are possible using modern high-performance computing. We demonstrate the utility of our method by examining elastic scattering of protons by hydrogen and helium atoms, problems familiar to undergraduate students of atomic scattering. Application to ionization of helium using partial-wave expansions of the projectile wavefunction, which has long been desirable in heavy-ion collision physics, is thus quite feasible.

  10. High-resolution spectrograms of ion acoustic waves in the solar wind

    NASA Technical Reports Server (NTRS)

    Kurth, W. S.; Gurnett, D. A.; Scarf, F. L.

    1979-01-01

    High-resolution, frequency-time spectrograms of ion acoustic waves in the solar wind obtained by the Voyager spacecraft at distances of up to 1.7 AU are examined. The plasma wave instrument on board the Voyager spacecraft used to acquire the spectra employs an electric dipole antenna with a 16-channel step frequency receiver and a high-bit-rate waveform receiver to detect and measure the electric field of plasma waves. Voyager spectrograms show that the ion acoustic waves consist of narrowband, rapidly varying bursts, lasting a few seconds or less, usually in the range between the plasma ion and electron frequencies. Spectrograms taken at 1.7 AU are shown to be essentially identical to similar measurements taken upstream of the earth's magnetosphere, which are produced by suprathermal protons streaming into the solar wind from the bow shock, and to those taken upstream of interplanetary shocks.

  11. Shock waves and double layers in a quantum electron-positron-ion plasma

    NASA Astrophysics Data System (ADS)

    Dip, P. R.; Hossen, M. A.; Salahuddin, M.; Mamun, A. A.

    2016-02-01

    The ion-acoustic (IA) shock waves and double layers (DLs) in an unmagnetized, dissipative, quantum electron-positron-ion (EPI) plasma (composed of a viscous heavy ion fluid, Fermi electrons and positrons) have been theoretically investigated. The higher-order Burgers and Gardner equations are derived by employing the reductive perturbation method. The basic features of the IA shock waves and the DLs are identified by analyzing the solutions of both the higher-order Burgers and Gardner equations. The ratio of the Fermi temperature of the positron to that of the electron, the Fermi pressure of electrons and positrons, the viscous force, the plasma particle number densities, etc. are found to change remarkably the basic features (viz. amplitude, width, phase speed, etc.) of the IA waves. The results of our investigation may be helpful in understanding the nonlinear features of localized IA waves propagating in quantum EPI plasmas which are ubiquitous in astrophysical, as well as laboratory, environments.

  12. Thermomechanical damage of nucleosome by the shock wave initiated by ion passing through liquid water

    NASA Astrophysics Data System (ADS)

    Yakubovich, Alexander V.; Surdutovich, Eugene; Solov'yov, Andrey V.

    2012-05-01

    We report on the results of full-atom molecular dynamics simulations of the heat spike in the water medium caused by the propagation of the heavy ion in the vicinity of its Bragg peak. High rate of energy transfer from an ion to the molecules of surrounding water environment leads to the rapid increase of the temperature of the molecules in the vicinity of ions trajectory. As a result of an abrupt increase of the temperature we observe the formation of the nanoscale shock wave propagating through the medium. We investigate the thermomechanical damage caused by the shock wave to the nucleosome located in the vicinity of heavy ion trajectory. We observe the substantial deformation of the DNA secondary structure. We show that the produced shock wave can lead to the thermomechanical breakage of the DNA backbone covalent bonds and present estimates for the number of such strand brakes per one cell nucleus.

  13. Parallel-velocity-shear-modified drift wave in negative ion plasmas

    NASA Astrophysics Data System (ADS)

    Ichiki, R.; Kaneko, T.; Hayashi, K.; Tamura, S.; Hatakeyama, R.

    2009-03-01

    A systematic investigation of the effects of a parallel velocity shear and negative ions on the collisionless drift wave instability has for the first time been realized by simultaneously using a segmented tungsten hot plate of a Q-machine and sulfur hexafluoride (SF6) gas in a magnetized potassium plasma. The parallel velocity shear of the positive ion flow tends to decrease the fluctuation level of the drift wave. The introduction of negative ions first increases the fluctuation level and then starts to decrease it at the negative ion exchange fraction of around 10%, while keeping the above-mentioned shear effect qualitatively. In addition, a simple dispersion relation based on the local model has been calculated to show that it can predict wave characteristics similar to the experimental results. Our findings provide a potential for gaining a more profound insight into the physics of space/circumterrestrial plasmas.

  14. Controlled high-energy ion acceleration with intense chirped standing waves

    NASA Astrophysics Data System (ADS)

    Mackenroth, Felix; Gonoskov, Arkady; Marklund, Mattias

    2016-10-01

    We present the latest results of the recently proposed ion acceleration mechanism ``chirped standing wave acceleration''. This mechanism is based on locking the electrons of a thin plasma layer to the moving nodes of a standing wave formed by a chirped laser pulse reflected from a mirror behind the thin layer. The resulting longitudinal charge separation field between the displaced electrons and the residual ions then accelerates the latter. Since the plasma layer is stabilized by the standing wave, the formation of plasma instabilities is suppressed. Furthermore, the experimentally accessible laser chirp provides a versatile tool for manipulating the resulting ion beam in terms of maximum particle energy, particle number and spectral distribution. Through this scheme, proton beams, with energy spectra peaked around 100 MeV, were shown to be feasible for pulse energies at the level of 10 J. Wallenberg Foundation within the Grant ''Plasma based compact ion sources'' (PLIONA).

  15. Acceleration of cometary H2O group pickup ions by obliquely propagating nonlinear magnetosonic waves

    NASA Astrophysics Data System (ADS)

    Srivastava, Krishna M.; Tsurutani, Bruce T.; Goldstein, Bruce E.; Sharma, V.; Okada, M.

    1993-12-01

    The observations made during the encounter with comet Giacobini Zinner show that the character of MHD turbulence is governed by the magnetosonic (MS) waves generated by the pickup ions via a resonant cyclotron instability. The interaction of cometary ions in the mass loaded solar wind with MS waves propagating away from the comet and oblique to the interplanetary magnetic field (IMF) is investigated using the test particle approach. Ion trajectories, distribution functions, widths of pitch angle scattering and energy diffusion are obtained. We have also investigated the relationship between pitch angle scattering and the three parameters, namely, alpha, the angle between the solar wind flow direction and the ambient magnetic field, thetaBK, the angle between the ambient magnetic field and the wave propagation vector, and the ion injection velocity.

  16. Noncontact, nondestructive elasticity evaluation of sound and demineralized human dental enamel using a laser ultrasonic surface wave dispersion technique

    NASA Astrophysics Data System (ADS)

    Wang, Hsiao-Chuan; Fleming, Simon; Lee, Yung-Chun; Law, Susan; Swain, Michael; Xue, Jing

    2009-09-01

    Laser ultrasonic nondestructive evaluation (NDE) methods have been proposed to replace conventional in vivo dental clinical diagnosis tools that are either destructive or incapable of quantifying the elasticity of human dental enamel. In this work, a laser NDE system that can perform remote measurements on samples of small dimensions is presented. A focused laser line source is used to generate broadband surface acoustic wave impulses that are detected with a simplified optical fiber interferometer. The measured surface wave velocity dispersion spectrum is in turn used to characterize the elasticity of the specimen. The NDE system and the analysis technique are validated with measurements of different metal structures and then applied to evaluate human dental enamel. Artificial lesions are prepared on the samples to simulate different states of enamel elasticity. Measurement results for both sound and lesioned regions, as well as lesions of different severity, are clearly distinguishable from each other and fit well with physical expectations and theoretical value. This is the first time, to the best of our knowledge, that a laser-based surface wave velocity dispersion technique is successfully applied on human dental enamel, demonstrating the potential for noncontact, nondestructive in vivo detection of the development of carious lesions.

  17. Coupling between whistler waves and ion-scale solitary waves: cluster measurements in the magnetotail during a substorm.

    PubMed

    Tenerani, A; Le Contel, O; Califano, F; Pegoraro, F; Robert, P; Cornilleau-Wehrlin, N; Sauvaud, J A

    2012-10-12

    We present a new model of self-consistent coupling between low frequency, ion-scale coherent structures with high frequency whistler waves in order to interpret Cluster data. The idea relies on the possibility of trapping whistler waves by inhomogeneous external fields where they can be spatially confined and propagate for times much longer than their characteristic electronic time scale. Here we take the example of a slow magnetosonic soliton acting as a wave guide in analogy with the ducting properties of an inhomogeneous plasma. The soliton is characterized by a magnetic dip and density hump that traps and advects high frequency waves over many ion times. The model represents a new possible way of explaining space measurements often detecting the presence of whistler waves in correspondence to magnetic depressions and density humps. This approach, here given by means of slow solitons, but more general than that, is alternative to the standard approach of considering whistler wave packets as associated with nonpropagating magnetic holes resulting from a mirror-type instability.

  18. Multiple Scattering of Sound by Internal Waves and Acoustic Characterization of Internal Wave Fields in Deep and Shallow Water

    DTIC Science & Technology

    2007-09-30

    less pronounced for steeper and shallower rays (Figs. 2 - 4). Results obtained with eigenrays and unconstrained rays are similar as long as the...intervals of the launch angle (yellow), and averages over the internal wave field realizations for eigenrays with additional averaging over 0.5º...realizations for eigenrays with additional averaging over 0.5º (magenta dots) and 2º (magenta line) intervals of the launch angle. Propagation range r

  19. Role of Parallel and Oblique Ion-Cyclotron Waves in Heating Ions in an Inhomogeneous Expanding Solar Wind Plasma

    NASA Astrophysics Data System (ADS)

    Ofman, L.; Ozak, N. O.; Vinas, A. F.

    2014-12-01

    In-situ observations of fast solar wind streams at distances of 0.29 AU and beyond by Helios and recently by MESSENGER, and at ~1 AU by STEREO, ACE, and Wind spacecraft provide direct evidence for the presence of turbulent Alfvén wave spectrum and of left-hand polarized ion-cyclotron waves as well as He++ - proton drift in the solar wind plasma. The waves and the super-Alfvénic drift can produce temperature anisotropies by resonant absorption and perpendicular heating of the ions. Measurements indicate that proton velocity distributions are generally non-Maxwellian with evidence for beams, while remote sensing observations of coronal holes have shown that heavy ions are hotter than protons with a temperature anisotropy greater than one (Ti,perp> Ti,||). In addition to the anisotropy, it is expected that the solar wind will be inhomogeneous on decreasing scales approaching the Sun. Here we use a 2.5 D hybrid code and extend previous work to study the heating of solar wind ions (H+, He+) in an inhomogeneous plasma background. We explore the effects of an initial ion drift and of a turbulent wave spectrum on the perpendicular ion heating and cooling and on the spectrum of the magnetic fluctuations in the inhomogeneous background solar wind. Using the 2D hybrid model we find that inhomogeneities in the plasma generate significant power of oblique waves in the solar wind plasma, in addition to enhanced heating compared to the homogenous solar wind case. We find that the cooling effect due to the solar wind expansion is only significant when sub-Alfvénic drifts are explored. On the other hand, the cooling is not significant in the presence of a super-Alfvénic drift, and it is even less significant when we include an inhomogeneous background density. We are able to reproduce the ion temperature anisotropy seen in observations and previous models and find that small-scale inhomogeneities in the inner heliosphere can have a significant impact on resonant wave ion

  20. Achieving High Resolution Ion Mobility Separations Using Traveling Waves in Compact Multiturn Structures for Lossless Ion Manipulations

    SciTech Connect

    Hamid, Ahmed M.; Garimella, Sandilya V. B.; Ibrahim, Yehia M.; Deng, Liulin; Zheng, Xueyun; Webb, Ian K.; Anderson, Gordon A.; Prost, Spencer A.; Norheim, Randolph V.; Tolmachev, Aleksey V.; Baker, Erin S.; Smith, Richard D.

    2016-09-20

    We report on ion mobility separations (IMS) achievable using traveling waves in a Structures for Lossless Ion Manipulations (TW-SLIM) module having a 44-cm path length and sixteen 90º turns. The performance of the TW-SLIM module was evaluated for ion transmission, and ion mobility separations with different RF, TW parameters and SLIM surface gaps in conjunction with mass spectrometry. In this work TWs were created by the transient and dynamic application of DC potentials. The TW-SLIM module demonstrated highly robust performance and the ion mobility resolution achieved even with sixteen close spaced turns was comparable to a similar straight path TW-SLIM module. We found an ion mobility peak capacity of ~ 31 and peak generation rate of 780 s-1 for TW speeds of <210 m/s using the current multi-turn TW-SLIM module. The separations achieved for isomers of peptides and tetrasaccharides were found to be comparable to those from a ~ 0.9-m drift tube-based IMS-MS platform operated at the same pressure (4 torr). The combined attributes of flexible design, low voltage requirements and lossless ion transmission through multiple turns for the present TW-SLIM module provides a basis for SLIM devices capable of achieving much greater ion mobility resolutions via greatly extended ion path lengths and compact serpentine designs that do not significantly impact the instrumentation profile, a direction described in a companion manuscript.

  1. Arbitrary amplitude electrostatic wave propagation in a magnetized dense plasma containing helium ions and degenerate electrons

    NASA Astrophysics Data System (ADS)

    Mahmood, S.; Sadiq, Safeer; Haque, Q.; Ali, Munazza Z.

    2016-06-01

    The obliquely propagating arbitrary amplitude electrostatic wave is studied in a dense magnetized plasma having singly and doubly charged helium ions with nonrelativistic and ultrarelativistic degenerate electrons pressures. The Fermi temperature for ultrarelativistic degenerate electrons described by N. M. Vernet [(Cambridge University Press, Cambridge, 2007), p. 57] is used to define ion acoustic speed in ultra-dense plasmas. The pseudo-potential approach is used to solve the fully nonlinear set of dynamic equations for obliquely propagating electrostatic waves in a dense magnetized plasma containing helium ions. The upper and lower Mach number ranges for the existence of electrostatic solitons are found which depends on the obliqueness of the wave propagation with respect to applied magnetic field and charge number of the helium ions. It is found that only compressive (hump) soliton structures are formed in all the cases and only subsonic solitons are formed for a singly charged helium ions plasma case with nonrelativistic degenerate electrons. Both subsonic and supersonic soliton hump structures are formed for doubly charged helium ions with nonrelativistic degenerate electrons and ultrarelativistic degenerate electrons plasma case containing singly as well as doubly charged helium ions. The effect of propagation direction on the soliton amplitude and width of the electrostatic waves is also presented. The numerical plots are also shown for illustration using dense plasma parameters of a compact star (white dwarf) from literature.

  2. Magnetic signatures of ion cyclotron waves during Cassini's high-inclination orbits of Saturn

    NASA Astrophysics Data System (ADS)

    Meeks, Zachary; Simon, Sven

    2017-02-01

    Based on magnetic field data from Cassini's high-inclination orbits of Saturn (radius RS = 60 , 268 km), we analyze the latitudinal distribution of ion cyclotron waves in the giant planet's magnetosphere. Our survey takes into account magnetic field data from all high-inclination orbits between 2004 and 2015. We analyze the dependency of the occurrence rate and amplitude of the ion cyclotron waves on radial distance ρ to Saturn's rotation axis, vertical distance z to Saturn's equatorial plane, and magnetic latitude λ. The occurrence rate of ion cyclotron waves is approximately 100% in Saturn's equatorial plane between the orbits of Enceladus and Dione and decreases to 50% at altitudes of | z | ≈ 0.6RS . Ion cyclotron waves were detected up to | z | = 2.0RS . The occurrence rate displays strong, non-monotonic variations with respect to ρ, z, and λ. The vertical amplitude profile of the waves exhibits an M-like pattern with two distinct peaks near z = ± 0.3RS and the central minimum at z=0. Compared to earlier observations, we find this M-like structure to be inflated in±z direction by a factor of three. The available magnetic field data provides only weak evidence for a local impact of Enceladus and Dione on the ion cyclotron wave field. Using the observed Doppler shift of the ion cyclotron wave frequency during Cassini's high-inclination orbits, we demonstrate the existence of a narrow band of bidirectional wave propagation. This band is centered around Saturn's equatorial plane and possesses a half-width of | z | = 0.15RS , which agrees well with the vertical scale height of Saturn's neutral cloud. To the north of this band, all ion cyclotron waves propagate towards the north (z > 0); and to the south, all waves propagate towards the south (z < 0). In companion with our previous study (Meeks et al., 2016), this survey provides the complete three-dimensional picture of the ion cyclotron wave field between the orbits of Enceladus and Rhea during the Cassini

  3. The interaction between ULF waves and thermal plasma ions in the magnetosphere

    NASA Astrophysics Data System (ADS)

    Zong, Qiugang

    2016-07-01

    During substorm activities, energetic particle injections associated with ULF waves have been detected when Cluster fleet was traveling inbound in the Southern Hemisphere. Substorm-injected energetic particles are strong and clearly modulated by these ULF waves. The ULF waves with the period of 1 min are probably the third harmonic mode. The periodic pitch angle dispersion signatures at 5.2-6.9 keV energy channel were detected by Cluster satellite. These thermal plasma have high coherence with the electric field of the third harmonic poloidal mode and satisfy the drift-bounce resonant condition of N = 2. In addition, ion outflows from the Earth's ionosphere (tens to hundreds of eV) are also observed to be modulated by these ULF waves. To the best of our knowledge, this is the first report to show that ULF waves can simultaneously interact with both substorm-injected "hot" particles from the magnetotail and cold outflow ions from the Earth's ionosphere.

  4. Performance of an ion-cyclotron-wave plasma apparatus operated in the radiofrequency sustained mode

    NASA Technical Reports Server (NTRS)

    Swett, C. C.; Woollett, R. R.

    1973-01-01

    An experimental study has been made of an ion-cyclotron-wave apparatus operated in the RF-sustained mode, that is, a mode in which the Stix RF coil both propagates the waves and maintains the plasma. Problems associated with this method of operation are presented. Some factors that are important to the coupling of RF power are noted. In general, the wave propagation and wave damping data agree with theory. Some irregularities in wave fields are observed. Maximum ion temperature is 870 eV at a density of five times 10 to the 12th power cu cm and RF power of 90 kW. Coupling efficiency is 70 percent.

  5. Nonplanar dust acoustic solitary waves in a strongly coupled dusty plasma with superthermal ions

    SciTech Connect

    El-Labany, S. K. Zedan, N. A.; El-Taibany, W. F. E-mail: eltaibany@du.edu.eg; El-Shamy, E. F.

    2014-12-15

    The nonplanar amplitude modulation of dust acoustic (DA) envelope solitary waves in a strongly coupled dusty plasma (SCDP) has been investigated. By using a reductive perturbation technique, a modified nonlinear Schrödinger equation (NLSE) including the effects of geometry, polarization, and ion superthermality is derived. The modulational instability (MI) of the nonlinear DA wave envelopes is investigated in both planar and nonplanar geometries. There are two stable regions for the DA wave propagation strongly affected by polarization and ion superthermality. Moreover, it is found that the nonlinear DA waves in spherical geometry are the more structurally stable. The larger growth rate of the nonlinear DA MI is observed in the cylindrical geometry. The salient characteristics of the MI in the nonplanar geometries cannot be found in the planar one. The DA wave propagation and the NLSE solutions are investigated both analytically and numerically.

  6. Ion-acoustic waves in a nonstationary ultra-cold neutral plasma

    SciTech Connect

    Mendonca, J. T.; Shukla, P. K.

    2011-04-15

    We consider the excitation and dispersion of electrostatic ion-acoustic (IA) waves in a nonstationary ultra-cold neutral plasma (UCNP). This can be seen as an extension of time-refraction models of photons and plasmons to the case of low-frequency IA waves in the UCNP. It is shown that temporal changes in the medium lead to a frequency-shift of the IA wave, and to the emission of the IA waves propagating in a direction opposite to each other. We consider an arbitrary temporal variation of the background plasma density, and determine the transmission and reflection coefficients. We also consider the influence of a fast ionization process, assumed inhomogeneous in volume and show that it excites a well-defined spectrum of ion-acoustic waves, which agree very well with a recent experimental observation.

  7. Ion acoustic kinetic Alfvén rogue waves in two temperature electrons superthermal plasmas

    NASA Astrophysics Data System (ADS)

    Kaur, Nimardeep; Saini, N. S.

    2016-10-01

    The propagation properties of ion acoustic kinetic Alfvén (IAKA) solitary and rogue waves have been investigated in two temperature electrons magnetized superthermal plasma in the presence of dust impurity. A nonlinear analysis is carried out to derive the Korteweg-de Vries (KdV) equation using the reductive perturbation method (RPM) describing the evolution of solitary waves. The effect of various plasma parameters on the characteristics of the IAKA solitary waves is studied. The dynamics of ion acoustic kinetic Alfvén rogue waves (IAKARWs) are also studied by transforming the KdV equation into nonlinear Schrödinger (NLS) equation. The characteristics of rogue wave profile under the influence of various plasma parameters (κc, μc, σ , θ) are examined numerically by using the data of Saturn's magnetosphere (Schippers et al. 2008; Sakai et al. 2013).

  8. Ion thermal effects on slow mode solitary waves in plasmas with two adiabatic ion species

    SciTech Connect

    Nsengiyumva, F. Hellberg, M. A. Mace, R. L.

    2015-09-15

    Using both the Sagdeev and Korteweg-de Vries (KdV) methods, ion thermal effects on slow mode ion acoustic solitons and double layers are investigated in a plasma with two adiabatic positive ion species. It is found that reducing the gap between the two ion thermal speeds by increasing the relative temperature of the cool ions increases the typical soliton/double layer speeds for all values of the ion-ion density ratio and reduces the range in the density ratio that supports double layers. The effect of increasing the relative cool ion temperature on the soliton/double layer amplitudes depends on the relative densities. For lower values of the ion density ratio, an increase in cool ion temperature leads to a significant decrease in soliton/double layer amplitude, so one may find that solitons of all permissible speeds lie within the range of KdV theory.

  9. Propagation of sound waves through a linear shear layer - A closed form solution

    NASA Technical Reports Server (NTRS)

    Scott, J. N.

    1978-01-01

    Closed form solutions are presented for sound propagation from a line source in or near a shear layer. The analysis is exact for all frequencies and is developed assuming a linear velocity profile in the shear layer. This assumption allows the solution to be expressed in terms of parabolic cylinder functions. The solution is presented for a line monopole source first embedded in the uniform flow and then in the shear layer. Solutions are also discussed for certain types of dipole and quadrupole sources. Asymptotic expansions of the exact solutions for small and large values of Strouhal number give expressions which correspond to solutions previously obtained for these limiting cases.

  10. Propagation of sound waves through a linear shear layer: A closed form solution

    NASA Technical Reports Server (NTRS)

    Scott, J. N.

    1978-01-01

    Closed form solutions are presented for sound propagation from a line source in or near a shear layer. The analysis was exact for all frequencies and was developed assuming a linear velocity profile in the shear layer. This assumption allowed the solution to be expressed in terms of parabolic cyclinder functions. The solution is presented for a line monopole source first embedded in the uniform flow and then in the shear layer. Solutions are also discussed for certain types of dipole and quadrupole sources. Asymptotic expansions of the exact solutions for small and large values of Strouhal number gave expressions which correspond to solutions previously obtained for these limiting cases.

  11. Ion gyroradius effects on particle trapping in kinetic Alfven waves along auroral field lines

    DOE PAGES

    Damiano, P. A.; Johnson, J. R.; Chaston, C. C.

    2016-11-10

    In this study, a 2-D self-consistent hybrid gyrofluid-kinetic electron model is used to investigate Alfven wave propagation along dipolar magnetic field lines for a range of ion to electron temperature ratios. The focus of the investigation is on understanding the role of these effects on electron trapping in kinetic Alfven waves sourced in the plasma sheet and the role of this trapping in contributing to the overall electron energization at the ionosphere. This work also builds on our previous effort by considering a similar system in the limit of fixed initial parallel current, rather than fixed initial perpendicular electric field.more » It is found that the effects of particle trapping are strongest in the cold ion limit and the kinetic Alfven wave is able to carry trapped electrons a large distance along the field line yielding a relatively large net energization of the trapped electron population as the phase speed of the wave is increased. However, as the ion temperature is increased, the ability of the kinetic Alfven wave to carry and energize trapped electrons is reduced by more significant wave energy dispersion perpendicular to the ambient magnetic field which reduces the amplitude of the wave. This reduction of wave amplitude in turn reduces both the parallel current and the extent of the high-energy tails evident in the energized electron populations at the ionospheric boundary (which may serve to explain the limited extent of the broadband electron energization seen in observations). Here, even in the cold ion limit, trapping effects in kinetic Alfven waves lead to only modest electron energization for the parameters considered (on the order of tens of eV) and the primary energization of electrons to keV levels coincides with the arrival of the wave at the ionospheric boundary.« less

  12. Ion gyroradius effects on particle trapping in kinetic Alfven waves along auroral field lines

    SciTech Connect

    Damiano, P. A.; Johnson, J. R.; Chaston, C. C.

    2016-11-10

    In this study, a 2-D self-consistent hybrid gyrofluid-kinetic electron model is used to investigate Alfven wave propagation along dipolar magnetic field lines for a range of ion to electron temperature ratios. The focus of the investigation is on understanding the role of these effects on electron trapping in kinetic Alfven waves sourced in the plasma sheet and the role of this trapping in contributing to the overall electron energization at the ionosphere. This work also builds on our previous effort by considering a similar system in the limit of fixed initial parallel current, rather than fixed initial perpendicular electric field. It is found that the effects of particle trapping are strongest in the cold ion limit and the kinetic Alfven wave is able to carry trapped electrons a large distance along the field line yielding a relatively large net energization of the trapped electron population as the phase speed of the wave is increased. However, as the ion temperature is increased, the ability of the kinetic Alfven wave to carry and energize trapped electrons is reduced by more significant wave energy dispersion perpendicular to the ambient magnetic field which reduces the amplitude of the wave. This reduction of wave amplitude in turn reduces both the parallel current and the extent of the high-energy tails evident in the energized electron populations at the ionospheric boundary (which may serve to explain the limited extent of the broadband electron energization seen in observations). Here, even in the cold ion limit, trapping effects in kinetic Alfven waves lead to only modest electron energization for the parameters considered (on the order of tens of eV) and the primary energization of electrons to keV levels coincides with the arrival of the wave at the ionospheric boundary.

  13. Unusual characteristics of electromagnetic waves excited by cometary newborn ions with large perpendicular energies

    NASA Technical Reports Server (NTRS)

    Brinca, A. L.; Tsurutani, B. T.

    1987-01-01

    The characteristics of electromagnetic waves excited by cometary newborn ions with large perpendicular energies are examined using a model of solar wind permeated by dilute drifting ring distributions of electrons and oxygen ions with finite thermal spreads. The model has parameters compatible with the ICE observations at the Giacobini-Zinner comet. It is shown that cometary newborn ions with large perpendicular energies can excite a wave mode with rest frame frequencies in the order of the heavy ion cyclotron frequency, Omega(i), and unusual propagation characteristics at small obliquity angles. For parallel propagation, the mode is left-hand circularly polarized, might be unstable in a frequency range containing Omega(i), and moves in the direction of the newborn ion drift along the static magnetic field.

  14. Relationship between wave energy and free energy from pickup ions in the Comet Halley environment

    NASA Technical Reports Server (NTRS)

    Huddleston, D. E.; Johnstone, A. D.

    1992-01-01

    The free energy available from the implanted heavy ion population at Comet Halley is calculated by assuming that the initial unstable velocity space ring distribution of the ions evolves toward a bispherical shell. Ultimately this free energy adds to the turbulence in the solar wind. Upstream and downstream free energies are obtained separately for the conditions observed along the Giotto spacecraft trajectory. The results indicate that the waves are mostly upstream propagating in the solar wind frame. The total free energy density always exceeds the measured wave energy density because, as expected in the nonlinear process of ion scattering, the available energy is not all immediately released. An estimate of the amount which has been released can be obtained from the measured oxygen ion distributions and again it exceeds that observed. The theoretical analysis is extended to calculate the k spectrum of the cometary-ion-generated turbulence.

  15. Ion acoustic and dust acoustic waves at finite size of plasma particles

    SciTech Connect

    Andreev, Pavel A. Kuz'menkov, L. S.

    2015-03-15

    We consider the influence of the finite size of ions on the properties of classic plasmas. We focus our attention at the ion acoustic waves for electron-ion plasmas. We also consider the dusty plasmas where we account the finite size of ions and particles of dust and consider the dispersion of dust acoustic waves. The finite size of particles is a classical effect as well as the Coulomb interaction. The finite size of particles considerably contributes to the properties of the dense plasmas in the small wavelength limit. Low temperature dense plasmas, revealing the quantum effects, are also affected by the finite size of plasma particles. Consequently, it is important to consider the finite size of ions in the quantum plasmas as well.

  16. Frequency-and-angular sounding of traveling ionospheric disturbances in the model of three-dimensional electron density waves

    NASA Astrophysics Data System (ADS)

    Galushko, V. G.; Kascheev, A. S.; Paznukhov, V. V.; Yampolski, Yu. M.; Reinisch, B. W.

    2008-08-01

    A new technique for diagnostics of traveling ionospheric disturbances (TIDs) uses measurements of arrival angles and Doppler frequency shift variations of HF radio signals reflected from the ionosphere. This technique is a further improvement of a frequency-and-angular sounding method previously suggested. Here we solve the respective inverse problem of reconstructing TID parameters by using a physically realistic three-dimensional model of electron density waves propagating through an ionospheric layer. The developed diagnostic algorithms were tested through computer simulations demonstrating the high efficiency of the proposed method. We also reprocessed the data collected in an earlier experiment carried out at the Millstone Hill Observatory in March 2001 using the new algorithms. In that campaign, HF signal trajectory parameters were recorded using the Digisonde instrument as a receiver monitoring continuous transmission from the CHU station. Comparison of the TID parameters determined with the frequency-and-angular sounding method and simultaneous incoherent scatter radar observations showed good agreement between the two diagnostic techniques with the differences of no greater than 10%.

  17. Oblique ion-acoustic cnoidal waves in two temperature superthermal electrons magnetized plasma

    SciTech Connect

    Panwar, A. Ryu, C. M.; Bains, A. S.

    2014-12-15

    A study is presented for the oblique propagation of ion acoustic cnoidal waves in a magnetized plasma consisting of cold ions and two temperature superthermal electrons modelled by kappa-type distributions. Using the reductive perturbation method, the nonlinear Korteweg de-Vries equation is derived, which further gives the solutions with a special type of cnoidal elliptical functions. Both compressive and rarefactive structures are found for these cnoidal waves. Nonlinear periodic cnoidal waves are explained in terms of plasma parameters depicting the Sagdeev potential and the phase curves. It is found that the density ratio of hot electrons to ions μ significantly modifies compressive/refractive wave structures. Furthermore, the combined effects of superthermality of cold and hot electrons κ{sub c},κ{sub h}, cold to hot electron temperature ratio σ, angle of propagation and ion cyclotron frequency ω{sub ci} have been studied in detail to analyze the height and width of compressive/refractive cnoidal waves. The findings in the present study could have important implications in understanding the physics of electrostatic wave structures in the Saturn's magnetosphere where two temperature superthermal electrons are present.

  18. Dust-ion-acoustic shock and solitary waves in a dusty electronegative plasma

    SciTech Connect

    Mamun, A. A.; Tasnim, S.

    2010-07-15

    A dusty electronegative plasma containing Boltzmann electrons, Boltzmann negative ions, warm positive ions, and charge fluctuating (negatively charged) stationary dust has been considered. The basic features of the shock and solitary waves, which are associated with positive ion dynamics and dust charge fluctuation, have been investigated by employing the reductive perturbation method. It has been shown that the dust charge fluctuation is a source of dissipation, and is responsible for the formation of dust-ion-acoustic shock structures. The implications of the results (obtained from this investigation) in space and laboratory experiments have been discussed.

  19. Integrating a Traveling Wave Tube into an AECR-U ion source

    SciTech Connect

    Covo, Michel Kireeff; Benitez, Janilee Y.; Ratti, Alessandro; Vujic, Jasmina L.

    2011-07-01

    An RF system of 500W - 10.75 to 12.75 GHz was designed and integrated into the Advanced Electron Cyclotron Resonance - Upgrade (AECR-U) ion source of the 88-Inch Cyclotron at Lawrence Berkeley National Laboratory. The AECR-U produces ion beams for the Cyclotron giving large flexibility of ion species and charge states. The broadband frequency of a Traveling Wave Tube (TWT) allows modifying the volume that couples and heats the plasma. The TWT system design and integration with the AECR-U ion source and results from commissioning are presented.

  20. Drift wave stabilized by an additional streaming ion or plasma population.

    PubMed

    Bashir, M F; Vranjes, J

    2015-03-01

    It is shown that the universally unstable kinetic drift wave in an electron-ion plasma can very effectively be suppressed by adding an extra flowing ion (or plasma) population. The effect of the flow of the added ions is essential, their response is of the type (vph-vf0)exp[-(vph-vf0)2], where vf0 is the flow speed and vph is the phase speed parallel to the magnetic field vector. The damping is strong and it is mainly due to this ion exponential term, and this remains so for vf0

  1. Cold Electronstatic Ion Cyclotron Waves for Preionization and IBW Launching in LHD

    SciTech Connect

    Masayuki Ono

    1999-04-01

    A folded waveguide with E|| polarization is being installed on LHD device. The main purpose of the folded waveguide is to pre-ionize and create good target plasmas. The present manuscript proposes a launching of IBW via CESICW (Cold Electrostatic Ion Cyclotron Wave) for heating the core of LHD with the folded waveguide. The core heating can be accomplished by adding a minority hydrogen ion species in a helium majority plasma facilitating the mode-transformation of CESICW into IBW at the ion-ion hybrid resonance.

  2. Self-Consistent Model of Magnetospheric Ring Current and Propagating Electromagnetic Ion Cyclotron Waves. 2; Waves, Precipitating Ring Current Ions, and Thermal Electron Heating

    NASA Technical Reports Server (NTRS)

    Khazanov, G. V.; Gamayunov, K. V.; Gallagher, D. L.

    2006-01-01

    This paper is dedicated to further presentations and discussions of the results from our new global self-consistent theoretical model of interacting ring current ions and electromagnetic ion cyclotron waves [Khazanov et al., 2006; here referred to as Paper 1]. In order to adequately take into account the wave propagation and refraction in a multi-ion plasmasphere, we explicitly include the ray tracing equations in our previous self-consistent model and use the general form of the wave kinetic equation [for details see Paper 1]. To demonstrate the effects of the EMIC wave propagation and refraction on the RC proton precipitations and heating of the thermal plasmaspheric electrons we simulate the May 1998 storm. The main findings of our simulation can be summarized as follows. Firstly, the wave induced precipitations have a quite fine structure, and are highly organized by location of the plasmapause gradient. The strongest fluxes of about 4 (raised dot) 10(exp 6) [(cm (raised dot) s (raised dot) sr)(sup -l)] are observed during the main and early recovery phases of the storm. The very interesting and probably more important finding is that in a number of cases the most intense precipitating fluxes are not simply connected to the most intense EMIC waves. The character of the EMIC wave power spectral density distribution over the equatorial wave normal angle is an extremely crucial for the effectiveness of the RC ion scattering. Secondly, comparison of the global proton precipitating patterns with the results from other ring current model [Kozyra et al., 1997] reveals that although we observe a qualitative agreement between localizations of the wave induced fluxes in the models, there is no quantitative agreement between the magnitudes of these fluxes. These differences are mainly due to a qualitative difference between the characters of the EMIC wave power spectral density distributions over the equatorial wave normal angle. Finally, the two energy sources to the

  3. Interaction between high harmonic fast waves and fast ions in NSTX/NSTX-U plasmas

    NASA Astrophysics Data System (ADS)

    Bertelli, N.; Valeo, E. J.; Gorelenkova, M.; Green, D. L.; RF SciDAC Team

    2016-10-01

    Fast wave (FW) heating in the ion cyclotron range of frequency (ICRF) has been successfully used to sustain and control the fusion plasma performance, and it will likely play an important role in the ITER experiment. As demonstrated in the NSTX and DIII-D experiments the interactions between fast waves and fast ions can be so strong to significantly modify the fast ion population from neutral beam injection. In fact, it has been recently found in NSTX that FWs can modify and, under certain conditions, even suppress the energetic particle driven instabilities, such as toroidal Alfvén eigenmodes and global Alfvén eigenmodes and fishbones. This paper examines such interactions in NSTX/NSTX-U plasmas by using the recent extension of the RF full-wave code TORIC to include non-Maxwellian ions distribution functions. Particular attention is given to the evolution of the fast ions distribution function w/ and w/o RF. Tests on the RF kick-operator implemented in the Monte-Carlo particle code NUBEAM is also discussed in order to move towards a self consistent evaluation of the RF wave-field and the ion distribution functions in the TRANSP code. Work supported by US DOE Contract DE-AC02-09CH11466.

  4. Ion Cyclotron Waves Observed in the Comet Halley: A New Look to Giotto Observations

    NASA Astrophysics Data System (ADS)

    Rodriguez-Martinez, M. R.; Blanco-Cano, X.; Aguilar-Rodriguez, E.; Haro-Corzo, S. S. A. R., Sr.; Arriaga-Contreras, V. V. R.

    2015-12-01

    Ion Cyclotron Waves (ICW) were observed with Giotto spacecraft. Magnetic field data have been analyzed in the past to determine the nature of ICW and compared with other comets, as Giacobini-Zinner and Grigg-Skjellerup. It is important to develop tools that allow re-analyze these data in order to know better the characteristics of these waves. In this work we have applied a Fast Fourier Transform (FFT) analysis in which we define the transverse and compressive powers for a better contrast and characterization of ICW. The information obtained will be presented through dynamic spectra in several time intervals. This tool will allow to explore the possibility to check the existence of Harmonic Mode Waves (HMW) of these waves. Finally, we use linear kinetic theory, using WHAMP code, in order to determine conditions for wave growth in a plasma resembling the regions where these waves were observed.

  5. High-speed helicopter rotor noise - Shock waves as a potent source of sound

    NASA Technical Reports Server (NTRS)

    Farassat, F.; Lee, Yung-Jang; Tadghighi, H.; Holz, R.

    1991-01-01

    In this paper we discuss the problem of high speed rotor noise prediction. In particular, we propose that from the point of view of the acoustic analogy, shocks around rotating blades are sources of sound. We show that, although for a wing at uniform steady rectilinear motion with shocks the volume quadrupole and shock sources cancel in the far field to the order of 1/r, this cannot happen for rotating blades. In this case, some cancellation between volume quadrupoles and shock sources occurs, yet the remaining shock noise contribution is still potent. A formula for shock noise prediction is presented based on mapping the deformable shock surface to a time independent region. The resulting equation is similar to Formulation 1A of Langley. Shock noise prediction for a hovering model rotor for which experimental noise data exist is presented. The comparison of measured and predicted acoustic data shows good agreement.

  6. New theory on the reverberation of rooms. [considering sound wave travel time

    NASA Technical Reports Server (NTRS)

    Pujolle, J.

    1974-01-01

    The inadequacy of the various theories which have been proposed for finding the reverberation time of rooms can be explained by an attempt to examine what might occur at a listening point when image sources of determined acoustic power are added to the actual source. The number and locations of the image sources are stipulated. The intensity of sound at the listening point can be calculated by means of approximations whose conditions for validity are given. This leads to the proposal of a new expression for the reverberation time, yielding results which fall between those obtained through use of the Eyring and Millington formulae; these results are made to depend on the shape of the room by means of a new definition of the mean free path.

  7. On the nonlinear dynamics of breathers waves in electronegative plasmas with Maxwellian negative ions

    NASA Astrophysics Data System (ADS)

    El-Tantawy, S. A.; Wazwaz, A. M.; Ali Shan, S.

    2017-02-01

    Theoretical investigations depending on the observation data are carried out for the nonlinear amplitude modulation of ion-acoustic waves propagating in an unmagnetized plasma composed of Maxwellian electrons and light negative ions in addition to mobile cold positive ions. The basic set of fluid equations is reduced to a nonlinear Schrödinger equation (NLSE) for describing the modulational instability process. The regions of the stable and unstable wavepackets have been confined precisely for various regimes. Moreover, the criteria for the existence of the breathers have been obtained. Analytical solutions of the NLSE in the forms of Akhmediev breathers, Kuznetsov-Ma (KM) solitons, and rogue waves are obtained. The characteristics of the profile of Akhmediev breathers, KM solitons, and freak waves are examined depending on the relevant physical parameters of the observed data.

  8. Nonlinear theory of electron neutralization waves in ions beams with dissipation

    NASA Technical Reports Server (NTRS)

    Wilhelm, H. E.

    1974-01-01

    An analytical theory of nonlinear neutralization waves generated by injection of electrons from a grid in the direction of a homogeneous ion beam of uniform velocity and infinite extension is presented. The electrons are assumed to interact with the ions through the self-consistent space charge field and by strong collective interactions, while diffusion in the pressure gradient is disregarded (zero-temperature approximation). The associated nonlinear boundary-value problem is solved in closed form by means of a von Mises transformation. It is shown that the electron gas moves into the ion space in the form of a discontinuous neutralization wave, which exhibits a periodic field structure (incomplete neutralization). This periodic wave structure is damped out by intercomponent momentum transfer - i.e., after a few relaxation lengths a quasi-neutral plasma results.

  9. Ion conics and counterstreaming electrons generated by lower hybrid waves in the earth's magnetosphere

    NASA Technical Reports Server (NTRS)

    Chang, Tom; Crew, Geoffrey B.; Retterrer, John M.; Jasperse, John R.

    1989-01-01

    The exotic phenomenon of energetic ion-conic and counterstreaming electron formation by lower hybrid waves along discrete auroral field lines in the earth magnetosphere is considered. Mean-particle calculations, plasma simulations, and analytical treatments of the acceleration processes are described. It is shown that, in the primary auroral electron-beam region, lower hybrid waves could be an efficient mechanism for the transverse heating of H (+) and O(+) ions of ionospheric origin, as well as for the field-aligned heating of the ambient electrons leading to coincident counterstreaming electron distributions. For O(+) ions to be energized by such a wave-particle interaction process, however, some sort of preheating mechanism is required.

  10. PIC simulation of compressive and rarefactive dust ion-acoustic solitary waves

    NASA Astrophysics Data System (ADS)

    Li, Zhong-Zheng; Zhang, Heng; Hong, Xue-Ren; Gao, Dong-Ning; Zhang, Jie; Duan, Wen-Shan; Yang, Lei

    2016-08-01

    The nonlinear propagations of dust ion-acoustic solitary waves in a collisionless four-component unmagnetized dusty plasma system containing nonextensive electrons, inertial negative ions, Maxwellian positive ions, and negatively charged static dust grains have been investigated by the particle-in-cell method. By comparing the simulation results with those obtained from the traditional reductive perturbation method, it is observed that the rarefactive KdV solitons propagate stably at a low amplitude, and when the amplitude is increased, the prime wave form evolves and then gradually breaks into several small amplitude solitary waves near the tail of soliton structure. The compressive KdV solitons propagate unstably and oscillation arises near the tail of soliton structure. The finite amplitude rarefactive and compressive Gardner solitons seem to propagate stably.

  11. Nonlinear features of ion acoustic shock waves in dissipative magnetized dusty plasma

    NASA Astrophysics Data System (ADS)

    Sahu, Biswajit; Sinha, Anjana; Roychoudhury, Rajkumar

    2014-10-01

    The nonlinear propagation of small as well as arbitrary amplitude shocks is investigated in a magnetized dusty plasma consisting of inertia-less Boltzmann distributed electrons, inertial viscous cold ions, and stationary dust grains without dust-charge fluctuations. The effects of dissipation due to viscosity of ions and external magnetic field, on the properties of ion acoustic shock structure, are investigated. It is found that for small amplitude waves, the Korteweg-de Vries-Burgers (KdVB) equation, derived using Reductive Perturbation Method, gives a qualitative behaviour of the transition from oscillatory wave to shock structure. The exact numerical solution for arbitrary amplitude wave differs somehow in the details from the results obtained from KdVB equation. However, the qualitative nature of the two solutions is similar in the sense that a gradual transition from KdV oscillation to shock structure is observed with the increase of the dissipative parameter.

  12. Dust Acoustic Solitary Waves in Dusty Plasma with Trapped Electrons Having Different Temperature Nonthermal Ions

    NASA Astrophysics Data System (ADS)

    Deka, Manoj Kr.

    2016-12-01

    In this report, a detailed investigation on the study of dust acoustics solitary waves solution with negatively dust charge fluctuation in dusty plasma corresponding to lower and higher temperature nonthermal ions with trapped electrons is presented. We consider temporal variation of dust charge as a source of dissipation term to derive the lower order modified Kadomtsev-Petviashvili equation by using the reductive perturbation technique. Solitary wave solution is obtained with the help of sech method in presence of trapped electrons and low (and high) temperature nonthermal ions. Both nonthermality of ions and trapped state of the electrons are found to have an imperative control on the nonlinear coefficient, dissipative coefficient as well as height of the wave potential.

  13. Room acoustics analysis using circular arrays: an experimental study based on sound field plane-wave decomposition.

    PubMed

    Torres, Ana M; Lopez, Jose J; Pueo, Basilio; Cobos, Maximo

    2013-04-01

    Plane-wave decomposition (PWD) methods using microphone arrays have been shown to be a very useful tool within the applied acoustics community for their multiple applications in room acoustics analysis and synthesis. While many theoretical aspects of PWD have been previously addressed in the literature, the practical advantages of the PWD method to assess the acoustic behavior of real rooms have been barely explored so far. In this paper, the PWD method is employed to analyze the sound field inside a selected set of real rooms having a well-defined purpose. To this end, a circular microphone array is used to capture and process a number of impulse responses at different spatial positions, providing angle-dependent data for both direct and reflected wavefronts. The detection of reflected plane waves is performed by means of image processing techniques applied over the raw array response data and over the PWD data, showing the usefulness of image-processing-based methods for room acoustics analysis.

  14. Near-Axial Interference Effects for Long-Range Sound Transmissions through Ocean Internal Waves

    DTIC Science & Technology

    2007-09-30

    Prescribed by ANSI Std Z39-18 While the eikonal equation can be solved for the ray paths and travel times can be calculated by integrating the index of... point source problem with the parabolic index of refraction squared was studied in detail in Refs. (3) and (4). The integral representation of the...for the axial wave can be obtained as well by transforming the integral representation of the exact solution of the point source problem. But this

  15. Effect of ionic temperature on the modulational instability of ion acoustic waves in the presence of a magnetic field

    NASA Astrophysics Data System (ADS)

    Murtaza, G.; Salahuddin, M.

    1981-12-01

    The modulational instability of ion acoustic waves is studied in the presence of a dc magnetic field, taking the ion temperature into account. It is well known that the instability sets in for wave numbers exceeding 1.47 kD when there is no magnetic field and the ion temperature is negligible. The instability behaviour, however, changes drastically when either the magnetic field is switched on or the ion temperature becomes important or both. In general three different regions emerge wherein the waves becomes modulationally unstable. The relative sizes of these regions change as the magnetic field, the angle of propagation and the ion temperature are varied.

  16. Suppression of stimulated Brillouin instability of a beat-wave of two lasers in multiple-ion-species plasmas

    SciTech Connect

    Yadav, Pinki; Gupta, D. N. Avinash, K.

    2016-01-15

    Stimulated Brillouin instability of a beat-wave of two lasers in plasmas with multiple-ion-species (negative-ions) was studied. The inclusion of negative-ions affects the growth of ion-acoustic wave in Brillouin scattering. Thus, the growth rate of instability is suppressed significantly by the density of negative-ions. To obey the phase-matching condition, the growth rate of the instability attains a maxima for an appropriate scattering angle (angle between the pump and scattered sideband waves). This study would be technologically important to have diagnostics in low-temperature plasmas.

  17. Adiabatic effects of electrons and ions on electro-acoustic solitary waves in an adiabatic dusty plasma

    NASA Astrophysics Data System (ADS)

    Tanjia, Fatema; Mamun, A. A.

    2009-02-01

    A dusty plasma consisting of negatively charged cold dust, adiabatic hot ions, and inertia-less adiabatic hot electrons has been considered. The adiabatic effects of electrons and ions on the basic properties of electro-acoustic solitary waves associated with different types of electro-acoustic (viz. ion-acoustic (IA), dust ion-acoustic (DIA), and dust acoustic (DA)) waves are thoroughly investigated by the reductive perturbation method. It is found that the basic properties of the IA, DIA, and DA waves are significantly modified by the adiabatic effects of ions and inertia-less electrons. The implications of our results in space and laboratory dusty plasmas are briefly discussed.

  18. The radiation of sound by the instability waves of a compressible plane turbulent shear layer

    NASA Technical Reports Server (NTRS)

    Tam, C. K. W.; Morris, P. J.

    1980-01-01

    The problem of acoustic radiation generated by instability waves of a compressible plane turbulent shear layer is solved. The solution provided is valid up to the acoustic far-field region. It represents a significant improvement over the solution obtained by classical hydrodynamic-stability theory which is essentially a local solution with the acoustic radiation suppressed. The basic instability-wave solution which is valid in the shear layer and the near-field region is constructed in terms of an asymptotic expansion using the method of multiple scales. This solution accounts for the effects of the slightly divergent mean flow. It is shown that the multiple-scales asymptotic expansion is not uniformly valid far from the shear layer. Continuation of this solution into the entire upper half-plane is described. The extended solution enables the near- and far-field pressure fluctuations associated with the instability wave to be determined. Numerical results show that the directivity pattern of acoustic radiation into the stationary medium peaks at 20 degrees to the axis of the shear layer in the downstream direction for supersonic flows. This agrees qualitatively with the observed noise-directivity patterns of supersonic jets.

  19. Sound speed estimation using wave-based ultrasound tomography: theory and GPU implementation

    NASA Astrophysics Data System (ADS)

    Roy, O.; Jovanović, I.; Hormati, A.; Parhizkar, R.; Vetterli, M.

    2010-03-01

    We present preliminary results obtained using a time domain wave-based reconstruction algorithm for an ultrasound transmission tomography scanner with a circular geometry. While a comprehensive description of this type of algorithm has already been given elsewhere, the focus of this work is on some practical issues arising with this approach. In fact, wave-based reconstruction methods suffer from two major drawbacks which limit their application in a practical setting: convergence is difficult to obtain and the computational cost is prohibitive. We address the first problem by appropriate initialization using a ray-based reconstruction. Then, the complexity of the method is reduced by means of an efficient parallel implementation on graphical processing units (GPU). We provide a mathematical derivation of the wave-based method under consideration, describe some details of our implementation and present simulation results obtained with a numerical phantom designed for a breast cancer detection application. The source code of our GPU implementation is freely available on the web at www.usense.org.

  20. Predicting electromagnetic ion cyclotron wave amplitude from unstable ring current plasma conditions

    NASA Astrophysics Data System (ADS)

    Fu, Xiangrong; Cowee, Misa M.; Jordanova, Vania K.; Gary, S. Peter; Reeves, Geoffrey D.; Winske, Dan

    2016-11-01

    Electromagnetic ion cyclotron (EMIC) waves in the Earth's inner magnetosphere are enhanced fluctuations driven unstable by ring current ion temperature anisotropy. EMIC waves can resonate with relativistic electrons and play an important role in precipitation of MeV radiation belt electrons. In this paper, we investigate the excitation and saturation of EMIC instability in a homogeneous plasma using both linear theory and nonlinear hybrid simulations. We have explored a four-dimensional parameter space, carried out a large number of simulations, and derived a scaling formula that relates the saturation EMIC wave amplitude to initial plasma conditions. Such scaling can be used in conjunction with ring current models like ring current-atmosphere interactions model with self-consistent magnetic field to provide global dynamic EMIC wave maps that will be more accurate inputs for radiation belt modeling than statistical models.