WorldWideScience

Sample records for dispersive ion waves

  1. Dispersion surfaces and ion wave instabilities in space plasmas

    International Nuclear Information System (INIS)

    Andre, M

    1985-08-01

    In this thesis, the dispersion relation of linear waves in a non-relativistic, collisionless and homogeneous plasma in a uniform magnetic field, is solved numerically. Both electrostatic and elecromagnetic waves with frequencies from below the ion gyrofrequency to above the electron gyrofrequency are studied for all angles of propagation. Modes occurring in a cold plasma as well as waves dependent on thermal effects are included. Dispersion surfaces, that is plots of frequency versus wavevector components, are presented for some models of space plasmas. Waves with frequencies of the order of the ion gyrofrequency (ion waves), are well known to exist in space plasmas. In this thesis, the generation of ion waves by ion distributions with loss-cones or temperature anisotropies, or by beams of charged particles, is investigated by numerical methods. Effects of heavy ions are considered. Dispersion surfaces and analytical arguments are used to clarify the results. It is shown that particle beams and ion loss-cone distributions can generate electrostatic ion waves, even when a significant amount of the electrons are cool. These calculations are in agreement with simultaneous observatons of waves and particles obtained by a satellite on auroral field lines. (author)

  2. Hot-ion Bernstein wave with large kparallel

    International Nuclear Information System (INIS)

    Ignat, D.W.; Ono, M.

    1995-01-01

    The complex roots of the hot plasma dispersion relation in the ion cyclotron range of frequencies have been surveyed. Progressing from low to high values of perpendicular wave number k perpendicular we find first the cold plasma fast wave and then the well-known Bernstein wave, which is characterized by large dispersion, or large changes in k perpendicular for small changes in frequency or magnetic field. At still higher k perpendicular there can be two hot plasma waves with relatively little dispersion. The latter waves exist only for relatively large k parallel, the wave number parallel to the magnetic field, and are strongly damped unless the electron temperature is low compared to the ion temperature. Up to three mode conversions appear to be possible, but two mode conversions are seen consistently

  3. Electromagnetic Waves Dispersion and Interaction of an Annular Beam-Ion Channel System in Plasma Waveguide

    Directory of Open Access Journals (Sweden)

    Jixiong Xiao

    2017-01-01

    Full Text Available A linear theory for the electromagnetic properties and interactions of an annular beam-ion channel system in plasma waveguide is presented. The dispersion relations for two families of propagating modes, including the electrostatic and transverse magnetic modes, are derived. The dependencies of the dispersion behavior and interaction for different wave modes on the thickness of the annular beam and betatron oscillation frequency are studied in detail by numerical calculations. The results show that the inner and outer radii of the beam have different influences on propagation properties of the electrostatic and electromagnetic modes with different betatron oscillation parameters. In the weak ion channel situation, the two types of electrostatic waves, that is, space charge and betatron modes, have no interaction with the transverse magnetic modes. However, in the strong ion channel situation, the transverse magnetic modes will have two branches and a low frequency mode emerged as the new branch. In this case, compared with the solid beam case, the betatron modes not only can interact with the high frequency branch at small wavenumber but also can interact with the low frequency branch at large wavenumber.

  4. Dispersion and absorption of longitudinal electro-kinetic wave in ion-implanted GaN semiconductor plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Soni, Dilip [Government P G Madhav Science College, Ujjain (M P) (India); Sharma, Giriraj, E-mail: grsharma@gmail.com [SRJ Government Girls’ College, Neemuch (M P) (India); Saxena, Ajay [Government College, Garoth, Dist. Mandsaur (M P) (India); Jadhav, Akhilesh [Government J Yoganandam Chhattisgarh College, Raipur (C G) (India)

    2015-07-31

    An analytical study on propagation characteristics of longitudinal electro-kinetic (LEK) waves is presented. Based on multi-fluid model of plasma, we have derived a dispersion relation for LEK waves in colloid laden GaN semiconductor plasmas. It is assumed that ions are implanted to form colloids in the GaN sample. The colloids are continuously bombarded by the plasma particles and stick on them, but they acquire a net negative charge due to relatively higher mobility of electrons. It is found from the dispersion relation that the presence of charged colloids not only modifies the existing modes but also supports new novel modes of LEKWs. It is hoped that the study would enhance understanding on dispersion and absorption of LEKWs and help in singling out the appropriate configurations in which GaN crystal would be better suited for fabrication of microwave devices.

  5. Electrostatic ion acoustic waves

    International Nuclear Information System (INIS)

    Hasegawa, A.

    1983-01-01

    In this paper, certain aspects of plasma physics are illustrated through a study of electrostatic ion acoustic waves. The paper consists of three Sections. Section II deals with linear properties of the ion acoustic wave including derivation of the dispersions relation with the effect of Landau damping and of an ambient magnetic field. The section also introduces the excitation processes of the ion acoustic wave due to an electron drift or to a stimulated Brillouin scattering. The nonlinear properties are introduced in Section III and IV. In Section III, incoherent nonlinear effects such as quasilinear and mode-coupling saturations of the instability are discussed. The coherent nonlinear effects such as the generation of ion acoustic solitons, shocks and weak double layers are presented in Section IV. (Auth.)

  6. Ion temperature via laser scattering on ion Bernstein waves

    International Nuclear Information System (INIS)

    Wurden, G.A.; Ono, M.; Wong, K.L.

    1981-10-01

    Hydrogen ion temperature has been measured in a warm toroidal plasma with externally launched ion Bernstein waves detected by heterodyne CO 2 laser scattering. Radial scanning of the laser beam allows precise determination of k/sub perpendicular to/ for the finite ion Larmor radius wave (ω approx. less than or equal to 2Ω/sub i/). Knowledge of the magnetic field strength and ion concentration then give a radially resolved ion temperature from the dispersion relation. Probe measurements and Doppler broadening of ArII 4806A give excellent agreement

  7. Nonlinear self-modulation of ion-acoustic waves

    International Nuclear Information System (INIS)

    Ikezi, H.; Schwarzenegger, K.; Simons, A.L.; Ohsawa, Y.; Kamimura, T.

    1978-01-01

    The nonlinear evolution of an ion-acoustic wave packet is studied. Experimentally, it is found that (i) nonlinear phase modulation develops in the wave packet; (ii) the phase modulation, together with the dispersion effect, causes expansion and breaking of the wave packet; (iii) the ions trapped in the troughs of the wave potential introduce self-phase modulation; and (iv) the ion-acoustic wave is stable with respect to the modulational instability. Computer simulations have reproduced the experimental results. The physical picture and the model equation describing the wave evolution are discussed

  8. Ion acoustic waves in pair-ion plasma: Linear and nonlinear analyses

    International Nuclear Information System (INIS)

    Saeed, R.; Mushtaq, A.

    2009-01-01

    Linear and nonlinear properties of low frequency ion acoustic wave (IAW) in pair-ion plasma in the presence of electrons are investigated. The dispersion relation and Kadomtsev-Petviashvili equation for linear/nonlinear IAW are derived from sets of hydrodynamic equations where the ion pairs are inertial while electrons are Boltzmannian. The dispersion curves for various concentrations of electrons are discussed and compared with experimental results. The predicted linear IAW propagates at the same frequencies as those of the experimentally observed IAW if n e0 ∼10 4 cm -3 . It is found that nonlinear profile of the ion acoustic solitary waves is significantly affected by the percentage ratio of electron number density and temperature. It is also determined that rarefactive solitary waves can propagate in this system. It is hoped that the results presented in this study would be helpful in understanding the salient features of the finite amplitude localized ion acoustic solitary pulses in a laboratory fullerene plasma.

  9. Langmuir wave dispersion relation in non-Maxwellian plasmas

    International Nuclear Information System (INIS)

    Ouazene, M.; Annou, R.

    2010-01-01

    The Langmuir wave dispersion relation is derived in partially ionized plasmas, where free electrons are confined to move in a nearest neighbor ions' potential well. The equilibrium velocity distribution function experiences then, a departure from Maxwell distribution function. The effect of the non-Maxwellian character of the distribution function on the Langmuir phase and group velocities as well as the phase matching conditions and the nonlinear growth rate of decay instability is investigated. The proposed Langmuir wave dispersion relation is relevant to dense and cryogenic plasmas.

  10. The influence of multiple ion species on Alfven wave dispersion and Alfven wave plasma heating

    International Nuclear Information System (INIS)

    Elfimov, A.G.; Tataronis, J.A.; Hershkowitz, N.

    1994-01-01

    In this paper, the effects of light impurities, such as deuterium, helium, or carbon, on Alfven wave dispersion characteristics are explored. It is shown that a small population of light impurities in a hydrogen plasma modify the dispersion of the global Alfven waves and the Alfven continuum in such a way that the wave frequency depends weakly on the toroidal wave number. It is also shown that the global Alfven wave enters into the Alfven continuum. Under these conditions, it is possible to heat plasma efficiently by employing an antenna with a broad toroidal wavelength spectrum. The relationship between impurity concentration and the efficiency of Alfven wave heating is explored. Under appropriate conditions, the results indicate that in the presence of impurities, Alfven waves can heat electrons predominantly in the central part of the plasma. This effect is explored via a series of numerical calculations of the heating specifically for the Phaedrus-T Alfven wave heating experiment [Phys. Fluids B 5, 2506 (1993)

  11. Wave-equation dispersion inversion

    KAUST Repository

    Li, Jing

    2016-12-08

    We present the theory for wave-equation inversion of dispersion curves, where the misfit function is the sum of the squared differences between the wavenumbers along the predicted and observed dispersion curves. The dispersion curves are obtained from Rayleigh waves recorded by vertical-component geophones. Similar to wave-equation traveltime tomography, the complicated surface wave arrivals in traces are skeletonized as simpler data, namely the picked dispersion curves in the phase-velocity and frequency domains. Solutions to the elastic wave equation and an iterative optimization method are then used to invert these curves for 2-D or 3-D S-wave velocity models. This procedure, denoted as wave-equation dispersion inversion (WD), does not require the assumption of a layered model and is significantly less prone to the cycle-skipping problems of full waveform inversion. The synthetic and field data examples demonstrate that WD can approximately reconstruct the S-wave velocity distributions in laterally heterogeneous media if the dispersion curves can be identified and picked. The WD method is easily extended to anisotropic data and the inversion of dispersion curves associated with Love waves.

  12. Plasmon band gap generated by intense ion acoustic waves

    International Nuclear Information System (INIS)

    Son, S.; Ku, S.

    2010-01-01

    In the presence of an intense ion acoustic wave, the energy-momentum dispersion relation of plasmons is strongly modified to exhibit a band gap structure. The intensity of an ion acoustic wave might be measured from the band gap width. The plasmon band gap can be used to block the nonlinear cascading channel of the Langmuir wave decay.

  13. Gyro-viscosity and linear dispersion relations in pair-ion magnetized plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Kono, M. [Faculty of Policy Studies, Chuo University, Tokyo 192-0393 (Japan); Vranjes, J. [Instituto de Astrofisica de Canarias, Tenerife E38205 (Spain); Departamento de Astrofisica, Universidad de La Laguna, Tenerife E38205 (Spain)

    2015-11-15

    A fluid theory has been developed by taking account of gyro-viscosity to study wave propagation characteristics in a homogeneous pair-ion magnetized plasma with a cylindrical symmetry. The exact dispersion relations derived by the Hankel-Fourier transformation are shown comparable with those observed in the experiment by Oohara and co-workers. The gyro-viscosity is responsible for the change in propagation characteristics of the ion cyclotron wave from forward to backward by suppressing the effect of the thermal pressure which normally causes the forward nature of dispersion. Although the experiment has been already explained by a kinetic theory by the present authors, the kinetic derivations are so involved because of exact particle orbits in phase space, finite Lamor radius effects, and higher order ion cyclotron resonances. The present fluid theory provides a simple and transparent structure to the dispersion relations since the gyro-viscosity is renormalized into the ion cyclotron frequency which itself indicates the backward nature of dispersion. The usual disadvantage of a fluid theory, which treats only fundamental modes of eigen-waves excited in a system and is not able to describe higher harmonics that a kinetic theory does, is compensated by simple derivations and clear picture based on the renormalization of the gyro-viscosity.

  14. Energy-dispersed ions in the plasma sheet boundary layer and associated phenomena: Ion heating, electron acceleration, Alfvén waves, broadband waves, perpendicular electric field spikes, and auroral emissions

    Directory of Open Access Journals (Sweden)

    A. Keiling

    2006-10-01

    Full Text Available Recent Cluster studies reported properties of multiple energy-dispersed ion structures in the plasma sheet boundary layer (PSBL that showed substructure with several well separated ion beamlets, covering energies from 3 keV up to 100 keV (Keiling et al., 2004a, b. Here we report observations from two PSBL crossings, which show a number of identified one-to-one correlations between this beamlet substructure and several plasma-field characteristics: (a bimodal ion conics (<1 keV, (b field-aligned electron flow (<1 keV, (c perpendicular electric field spikes (~20 mV/m, (d broadband electrostatic ELF wave packets (<12.5 Hz, and (e enhanced broadband electromagnetic waves (<4 kHz. The one-to-one correlations strongly suggest that these phenomena were energetically driven by the ion beamlets, also noting that the energy flux of the ion beamlets was 1–2 orders of magnitude larger than, for example, the energy flux of the ion outflow. In addition, several more loosely associated correspondences were observed within the extended region containing the beamlets: (f electrostatic waves (BEN (up to 4 kHz, (g traveling and standing ULF Alfvén waves, (h field-aligned currents (FAC, and (i auroral emissions on conjugate magnetic field lines. Possible generation scenarios for these phenomena are discussed. In conclusion, it is argued that the free energy of magnetotail ion beamlets drove a variety of phenomena and that the spatial fine structure of the beamlets dictated the locations of where some of these phenomena occurred. This emphasizes the notion that PSBL ion beams are important for magnetosphere-ionosphere coupling. However, it is also shown that the dissipation of electromagnetic energy flux (at altitudes below Cluster of the simultaneously occurring Alfvén waves and FAC was larger (FAC being the largest than the dissipation of beam kinetic energy flux, and thus these two energy carriers contributed more to the energy transport on PSBL field lines

  15. Ion acoustic waves in one- and two-negative ion species plasmas

    International Nuclear Information System (INIS)

    Ichiki, Ryuta; Shindo, Masako; Yoshimura, Shinji; Watanabe, Tsuguhiro; Kawai, Yoshinobu

    2001-01-01

    Ion acoustic waves in multi-ion plasmas including two negative ion species are investigated both numerically and experimentally. Numerically, the kinetic dispersion relation in two-negative ion plasmas is investigated. There are three modes of the ion acoustic waves in two-negative ion plasmas. In an Ar + -F - -SF 6 - plasma, only one of the three modes is dominant, regardless of the values of the electron and the ion temperatures. In a Xe + -F - -SF 6 - plasma, on the other hand, two modes can be important for a certain range of the electron-ion temperature ratio. The results also imply the possibility of the coexistence of the fast mode and the slow mode in one-negative ion plasmas. Experimentally, ion acoustic waves are observed in an Ar + -F - -SF 6 - plasma and are found to show a mode transition that agrees with the theoretical prediction for one of the three ion acoustic modes

  16. Properties of waves in an ion-beam plasma system

    International Nuclear Information System (INIS)

    Zank, G.P.; McKenzie, J.F.

    1988-01-01

    A multi-fluid approach is used to describe electrostatic interactions in an ion-beam plasma system. The structure of the wave equation governing the system exhibits the anisotropic and dispersive nature of the waves, whose properties are analysed in terms of the dispersion relation. The main purpose is to classify the different waves that can arise in an ion-beam plasma system in a systematic fashion. The classification is facilitated by introducing a three-parameter CMA diagram that illustrates the topological changes in not only the wavenumber, or refractive-index, surface but also the ray-velocity surface. Furthermore, an analytic expression governing wave amplification in an ion beam plasma is incorporated within the framework of a generalized CMA diagram. Such a description provides a simple interpretation for the onset of wave amplification in terms of a topological change in the refractive-index surface. It is hoped that by collating the wave properties in a unified form, many of the complicated wave features observed in an experiment may be interpreted more easily. (author)

  17. Self excitation of second harmonic ion-acoustic waves in a weakly magnetized plasma

    International Nuclear Information System (INIS)

    Tsukabayashi, I.; Yagishita, T.; Nakamura, Y.

    1994-01-01

    Electrostatic ion-acoustic waves in a weakly magnetized plasma are investigated experimentally. It is observed that finite amplitudes ion acoustic waves excite a new second harmonic wave train behind the initial ion waves excite a new second harmonic wave train behind the initial ion waves in a parallel magnetic field. The excitation of higher harmonic waves can be explained by non-linearity of finite amplitude ion-acoustic waves. The newly excited second harmonics waves satisfy a dispersion relation of the ion-acoustic waves. (author). 3 refs, 5 figs

  18. Three-dimensional stability of solitary kinetic Alfven waves and ion-acoustic waves

    International Nuclear Information System (INIS)

    Ghosh, G.; Das, K.P.

    1994-01-01

    Starting from a set of equations that lead to a linear dispersion relation coupling kinetic Alfven waves and ion-acoustic waves, three-dimensional KdV equations are derived for these waves. These equations are then used to investigate the three-dimensional stability of solitary kinetic Alfven waves and ion-acoustic waves by the small-k perturbation expansion method of Rowlands and Infeld. For kinetic Alfven waves it is found that there is instability if the direction of the plane-wave perturbation lies inside a cone, and the growth rate of the instability attains a maximum when the direction of the perturbation lies in the plane containing the external magnetic field and the direction of propagation of the solitary wave. For ion-acoustic waves the growth rate of instability attains a maximum when the direction of the perturbation lies in a plane perpendicular to the direction of propagation of the solitary wave. (Author)

  19. Ion temperature effects on magnetotail Alfvén wave propagation and electron energization: ION TEMPERATURE EFFECTS ON ALFVÉN WAVES

    Energy Technology Data Exchange (ETDEWEB)

    Damiano, P. A. [Princeton Center for Heliophysics, Princeton Plasma Physics Laboratory, Princeton University, Princeton New Jersey USA; Johnson, J. R. [Princeton Center for Heliophysics, Princeton Plasma Physics Laboratory, Princeton University, Princeton New Jersey USA; Chaston, C. C. [Space Sciences Laboratory, University of California, Berkeley California USA; School of Physics, University of Sydney, Sydney New South Wales Australia

    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. External excitation of ion cyclotron drift waves in a two-ion species plasma

    International Nuclear Information System (INIS)

    Kando, M.; Ikezawa, S.; Sugai, H.

    1984-01-01

    Ion cyclotron drift waves propagating across a density gradient and a magnetic field have been excited externally in a two-ion species plasma, with its concentration ratio controlled. The measured dispersion relations agree with the theoretical predictions. (author)

  1. Excitation of electrostatic ion cyclotron wave in electron beam plasma system

    International Nuclear Information System (INIS)

    Fukumura, Takashi; Takamoto, Teruo

    1984-01-01

    The electrostatic ion cyclotron waves excited in an electron beam plasma system was investigated. The excitation condition of the waves was calculated by using Harris type dispersion relation under some assumption, and its comparison with the experimental result was made. Beam plasma discharge is a kind of RF discharge, and it is caused by the waves generated by the interaction of electron beam with plasma. It was shown that electrostatic ion cyclotron waves seemed to be the most probable as excited waves. But the excitation mechanism of these waves has not been concretely investigated. In this study, the excitation condition of electrostatic ion cyclotron waves was calculated as described above. The experimental apparatus and the results of potential, electric field and ion saturation current in beam plasma, electron drift motion in azimuthal direction and the waves excited in beam plasma are reported. The frequency of oscillation observed in beam plasma corresponds to the harmonics or subharmonics of ion cyclotron frequency. The calculation of Harris type dispersion relation, the numerical calculation and the comparison of the experimental result with the calculated result are described. (Kako, I.)

  2. Electromagnetic Cyclotron Waves in the Solar Wind: Wind Observation and Wave Dispersion Analysis

    Science.gov (United States)

    Jian, L. K.; Moya, P. S.; Vinas, A. F.; Stevens, M.

    2016-01-01

    Wind observed long-lasting electromagnetic cyclotron waves near the proton cyclotron frequency on 11 March 2005, in the descending part of a fast wind stream. Bi-Maxwellian velocity distributions are fitted for core protons, beam protons, and alpha-particles. Using the fitted plasma parameters we conduct kinetic linear dispersion analysis and find ion cyclotron and/or firehose instabilities grow in six of 10 wave intervals. After Doppler shift, some of the waves have frequency and polarization consistent with observation, thus may be correspondence to the cyclotron waves observed.

  3. Observation of large-amplitude ion acoustic wave in microwave-plasma interaction experiments

    International Nuclear Information System (INIS)

    Yugami, Noboru; Nishida, Yasushi

    1997-01-01

    Large amplitude ion acoustic wave, which is not satisfied with a linear dispersion relationship of ion acoustic wave, is observed in microwave-plasma interaction experiments. This ion acoustic wave is excited around critical density layer and begins to propagate to underdense region with a phase velocity one order faster than sound velocity C s , which is predicted by the linear theory, the phase velocity and the wave length of the wave decreases as it propagates. Finally, it converges to C s and strongly dumps. Diagnostic by the Faraday cup indicates that this ion acoustic wave is accompanied with a hot ion beam. (author)

  4. Electron Landau damping of ion Bernstein waves in tokamak plasmas

    International Nuclear Information System (INIS)

    Brambilla, M.

    1998-01-01

    Absorption of ion Bernstein (IB) waves by electrons is investigated. These waves are excited by linear mode conversion in tokamak plasmas during fast wave (FW) heating and current drive experiments in the ion cyclotron range of frequencies. Near mode conversion, electromagnetic corrections to the local dispersion relation largely suppress electron Landau damping of these waves, which becomes important again, however, when their wavelength is comparable to the ion Larmor radius or shorter. The small Larmor radius wave equations solved by most numerical codes do not correctly describe the onset of electron Landau damping at very short wavelengths, and these codes, therefore, predict very little damping of IB waves, in contrast to what one would expect from the local dispersion relation. We present a heuristic, but quantitatively accurate, model which allows account to be taken of electron Landau damping of IB waves in such codes, without affecting the damping of the compressional wave or the efficiency of mode conversion. The possibilities and limitations of this approach are discussed on the basis of a few examples, obtained by implementing this model in the toroidal axisymmetric full wave code TORIC. (author)

  5. Kolmogorov spectra of long wavelength ion-drift waves in dusty plasmas

    International Nuclear Information System (INIS)

    Onishchenko, O.G.; Pokhotelov, O.A.; Sagdeev, R.Z.; Pavlenko, V.P.; Stenflo, L.; Shukla, P.K.; Zolotukhin, V.V.

    2002-01-01

    Weakly turbulent Kolmogorov spectra of ion-drift waves in dusty plasmas with an arbitrary ratio between the ion-drift and the Shukla-Varma frequencies are investigated. It is shown that in the long wavelength limit, when the contribution to the wave dispersion associated with the inhomogeneity of the dust component is larger than that related to the plasma inhomogeneity, the wave dispersion and the matrix interaction element coincide with those for the Rossby or the electron-drift waves described by the Charney or Hasegawa-Mima equations with an accuracy of unessential numerical coefficients. It is found that the weakly turbulent spectra related to the conservation of the wave energy are local and thus the energy flux is directed towards smaller spatial scales

  6. Landau damping in bi-dust ion-acoustic waves

    International Nuclear Information System (INIS)

    Castro, E.; Puerta, J.; Martin, P.; Cereceda, C.

    2006-01-01

    Ion acoustic dust waves in a bi-dust plasma are analyzed in this paper. In order to model this system, we assume the existence of two different kinds of grains, each characterized by a different radius. Relative velocities between grains and charge fluctuations are neglected. In order to derive the dispersion relation of this system, we use the well known hybrid fluid-kinetic model, in which ions are treated kinetically and other species as fluids. In this plasma, waves with non-relative velocities between species leads to damped waves with frequency modes, defined by the grain radius. The induced damping ratio is studied as a function of the grain and ion densities. (Author)

  7. Skeletonized wave equation of surface wave dispersion inversion

    KAUST Repository

    Li, Jing

    2016-09-06

    We present the theory for wave equation inversion of dispersion curves, where the misfit function is the sum of the squared differences between the wavenumbers along the predicted and observed dispersion curves. Similar to wave-equation travel-time inversion, the complicated surface-wave arrivals in traces are skeletonized as simpler data, namely the picked dispersion curves in the (kx,ω) domain. Solutions to the elastic wave equation and an iterative optimization method are then used to invert these curves for 2D or 3D velocity models. This procedure, denoted as wave equation dispersion inversion (WD), does not require the assumption of a layered model and is less prone to the cycle skipping problems of full waveform inversion (FWI). The synthetic and field data examples demonstrate that WD can accurately reconstruct the S-wave velocity distribution in laterally heterogeneous media.

  8. Wave Model Development in Multi-Ion Plasmas

    Directory of Open Access Journals (Sweden)

    Sung-Hee Song

    1999-06-01

    Full Text Available Near-earth space is composed of plasmas which embed a number of plasma waves. Space plasmas consist of electrons and multi-ion that determine local wave propagation characteristics. In multi-ion plasmas, it is di cult to find out analytic solution from the dispersion relation in general. In this work, we have developed a model with an arbitrary magnetic field and density as well as multi-ion plasmas. This model allows us to investigate how plasma waves behave when they propagate along realistic magnetic field lines, which are assumed by IGRF(International Geomagnetic Reference Field. The results are found to be useful for the analysis of the in situ observational data in space. For instance, if waves are assumed to propagate into the polar region, from the equatorial region, our model quantitatively shows how polarization is altered along earth travel path.

  9. Relativistic nonlinear waves of cyclotron in electron and electron-ion plasmas

    International Nuclear Information System (INIS)

    Bruno, R.

    1981-12-01

    Dispersion relations for electron-cyclotron and ion-cyclotron waves are examined in two models of plasmas, the first propagating in fluent electronic plasmas (''streaming'') as well as in fluent electron-ionic plasmas, and the last in fluent electron-ionic plasmas. The identification of the propagation modes is realized with the aid of a special technique of polinomial expantion of the dispersion relation in the limit of large frequencies and short wavelenghts. The analisys so developed on these dispersion relations for fluent plasmas show that: (i) the wave amplitudes are frequency dependent; (ii) the ''resonances'' frequencies of the respective estationary plasmas must be re-examined with the relations between wave amplitudes and the propagation frequencies near these frequencies; (iii) the electric field amplitudes for the non-linear waves of electron-cyclotron and ion-cyclotron go to zero in the limits of the respective cyclotron frequencies in both fluent plasma models. (M.W.O.) [pt

  10. Nonlinear ion acoustic waves in a quantum degenerate warm plasma with dust grains

    International Nuclear Information System (INIS)

    Dubinov, A. E.; Kolotkov, D. Yu.; Sazonkin, M. A.

    2011-01-01

    A study is made of the propagation of ion acoustic waves in a collisionless unmagnetized dusty plasma containing degenerate ion and electron gases at nonzero temperatures. In linear theory, a dispersion relation for isothermal ion acoustic waves is derived and an exact expression for the linear ion acoustic velocity is obtained. The dependence of the linear ion acoustic velocity on the dust density in a plasma is calculated. An analysis of the dispersion relation reveals parameter ranges in which the problem has soliton solutions. In nonlinear theory, an exact solution to the basic equations is found and examined. The analysis is carried out by Bernoulli’s pseudopotential method. The ranges of the phase velocities of periodic ion acoustic waves and the velocities of solitons are determined. It is shown that these ranges do not overlap and that the soliton velocity cannot be lower than the linear ion acoustic velocity. The profiles of the physical quantities in a periodic wave and in a soliton are evaluated, as well as the dependence of the critical velocity of solitons on the dust density in a plasma.

  11. Coherent scattering of CO2 light from ion-acoustic waves

    International Nuclear Information System (INIS)

    Peratt, A.L.; Watterson, R.L.; Derfler, H.

    1977-01-01

    Scattering of laser radiation from ion-acoustic waves in a plasma is investigated analytically and experimentally. The formulation predicts a coherent component of the scattered power on a largely incoherent background spectrum when the acoustic analog of Bragg's law and Doppler shift conditions are satisfied. The experiment consists of a hybrid CO 2 laser system capable of either low power continuous wave or high power pulsed mode operation. A heterodyne light mixing scheme is used to detect the scattered power. The proportionality predicted by the theory is verified by scattering from externally excited acoustic and ion-acoustic waves; continuous wave and pulsed modes in each case. Measurement of the ion-acoustic dispersion relation by continuous wave scattering is also presented

  12. Propagation and dispersion of electrostatic waves in the ionospheric E region

    Directory of Open Access Journals (Sweden)

    K. Iranpour

    Full Text Available Low-frequency electrostatic fluctuations in the ionospheric E region were detected by instruments on the ROSE rockets. The phase velocity and dispersion of plasma waves in the ionospheric E region are determined by band-pass filtering and cross-correlating data of the electric-field fluctuations detected by the probes on the ROSE F4 rocket. The results were confirmed by a different method of analysis of the same data. The results show that the waves propagate in the Hall-current direction with a velocity somewhat below the ion sound speed obtained for ionospheric conditions during the flight. It is also found that the waves are dispersive, with the longest wavelengths propagating with the lowest velocity.

  13. Propagation and dispersion of electrostatic waves in the ionospheric E region

    Directory of Open Access Journals (Sweden)

    K. Iranpour

    1997-07-01

    Full Text Available Low-frequency electrostatic fluctuations in the ionospheric E region were detected by instruments on the ROSE rockets. The phase velocity and dispersion of plasma waves in the ionospheric E region are determined by band-pass filtering and cross-correlating data of the electric-field fluctuations detected by the probes on the ROSE F4 rocket. The results were confirmed by a different method of analysis of the same data. The results show that the waves propagate in the Hall-current direction with a velocity somewhat below the ion sound speed obtained for ionospheric conditions during the flight. It is also found that the waves are dispersive, with the longest wavelengths propagating with the lowest velocity.

  14. Generation of ion-acoustic and magnetoacoustic waves in an RF helicon discharge

    International Nuclear Information System (INIS)

    Belov, A. S.; Markov, G. A.

    2006-01-01

    A study is made of the generation of ion-acoustic and magnetoacoustic waves in a discharge excited in an external magnetic field by an electromagnetic wave in the whistler frequency range (ω LH He , where ω LH = √(ω He ω Hi ) and ω He and ω Hi are the electron and ion gyrofrequencies, respectively). The excitation of acoustic waves is attributed to the decay of a high-frequency hybrid mode forming a plasma waveguide into low-frequency acoustic waves and new high-frequency waves that satisfy both the decay conditions and the waveguide dispersion relations. The excitation of acoustic waves is resonant in character because the conditions for the generation of waveguide modes and for the occurrence of the corresponding nonlinear wave processes should be satisfied simultaneously. An unexpected effect is the generation of magnetoacoustic waves by whistlers. A diagnostic technique is proposed that allows one to determine the thermal electron velocity by analyzing decay conditions and dispersion relations for waves in the discharge channel

  15. Skeletonized wave equation of surface wave dispersion inversion

    KAUST Repository

    Li, Jing; Schuster, Gerard T.

    2016-01-01

    We present the theory for wave equation inversion of dispersion curves, where the misfit function is the sum of the squared differences between the wavenumbers along the predicted and observed dispersion curves. Similar to wave-equation travel

  16. Effect of multi-ions on electromagnetic ion-cyclotron waves with a hot plasma around the polar cusp

    International Nuclear Information System (INIS)

    Patel, Soniya; Varma, P; Tiwari, M S

    2011-01-01

    Electromagnetic ion cyclotron (EMIC) instabilities with an isotropic ion beam and general loss-cone distribution of hot core plasmas are discussed. The growth rate of the wave, perpendicular heating of ions, parallel resonant energy and marginal instability of the EMIC waves in homogeneous plasmas are obtained using the dispersion relation for hot plasmas consisting of H + , He + ,O + ions and electrons. The wave is assumed to propagate parallel to the static magnetic field. The whole plasma is considered to consist of resonant and non-resonant particles permeated by the isotropic ion beam. It is assumed that the resonant particles and the ion beam participate in energy exchange with the wave, whereas the non-resonant particles support the oscillatory motion of the wave. We determined the variation in energies and growth rate in hot plasmas by the energy conservation method with a general loss-cone distribution function. We also discuss the effect of positive and negative ion beam velocity on the growth rate of the wave. The thermal anisotropy of the ions of the core plasma acts as a source of free energy for EMIC waves and enhances the growth rate. Heating of ions perpendicular to the magnetic field is discussed along with EMIC wave emission in the polar cusp region.

  17. Wave-equation dispersion inversion

    KAUST Repository

    Li, Jing; Feng, Zongcai; Schuster, Gerard T.

    2016-01-01

    We present the theory for wave-equation inversion of dispersion curves, where the misfit function is the sum of the squared differences between the wavenumbers along the predicted and observed dispersion curves. The dispersion curves are obtained

  18. Strong electron dissipation by a mode converted ion hybrid (Bernstein) wave

    International Nuclear Information System (INIS)

    Lashmore-Davies, C.N.; Ram, A.K.

    1996-01-01

    The fast wave approximation, extended to include the effects of electron dissipation, is used to calculate the power mode converted to the ion hybrid (Bernstein) wave in the vicinity of the ion hybrid resonance. The power absorbed from the fast wave by ion cyclotron damping and by electron Landau and transit time damping (including cross terms) is also calculated. The fast wave equation is solved for either the Budden configuration of a cut-off-resonance pair or the triplet configuration of cut-off-resonance-cut-off. The fraction mode converted is compared for the triplet case and the Budden multi-pass situation. The electron damping rate of the ion hybrid wave is obtained from the local dispersion relation and a ray tracing code is used to calculate the damping of the mode converted ion hybrid wave by the electrons as it propagates away from the resonance. Quantitative results for a range of conditions relevant to JET, TFTR and ITER are given. copyright 1996 American Institute of Physics

  19. Ion cyclotron wave excitation by double resonance coupling

    International Nuclear Information System (INIS)

    Fasoli, A.; Good, T.N.; Paris, P.J.; Skiff, F.; Tran, M.Q.

    1990-07-01

    A modulated high frequency wave is used to remotely excite low frequency oscillations in a linear, strongly magnetized plasma column. An electromagnetic wave is launched as an extraordinary mode across the plasma by an external waveguide in the Upper Hybrid frequency regime f=f UH =f ce =8 GHz, with P≤2 W. By frequency modulating (at f FM =1-60 kHz, with f ci ≅30 kHz) the pump wave, the resonant layer is swept radially across the profile and perpendicularly to the field lines at f=f FM . The resulting radial oscillation of the electron linear and non linear pressure can be considered to act as a source term for the ion wave. A localized virtual antenna is thereby created inside the plasma. Measurements of the ion dielectric response (interferograms and perturbed distribution functions) via laser induced fluorescence identify the two branches (forward, or ion-acoustic-like, and backward, or Bernstein, modes) of the electrostatic dispersion relation in the ion cyclotron frequency range. By changing the modulation bandwidth, and thus the spatial excursion of the oscillating resonant layer, a control on the perpendicular wavelength of the excited mode can be exerted. In particular, the possibility of selective excitation of the ion Bernstein wave is demonstrated experimentally. (author) 38 refs., 13 figs

  20. Enhanced coupling of the fast wave to electrons through mode conversion to the ion hybrid wave

    International Nuclear Information System (INIS)

    Lashmore-Davies, C.N.; Fuchs, V.; Ram, A.K.; Bers, A.

    1996-07-01

    The mode conversion of the fast compressional Alfven wave to the ion hybrid wave is analyzed with particular reference to a plasma with two ion species present in approximately equal proportions. Two configurations are considered, the first referring to the usual resonance-cut-off case and the second to a cut-off-resonance-cut-off situation. The optimum conditions for maximising the mode converted energy are given. The second order fast wave equation is generalised to include the effect of the parallel electric field. Hence, all ion and electron loss mechanisms for the fast wave are incorporated, including mode conversion at the two-ion hybrid resonance. The significance of the approximate equality of the two ion species concentrations is that the mode converted ion hybrid wave is damped only by the electrons. The damping of the ion hybrid wave is described with the aid of the local dispersion relation and by means of a toroidal ray tracing code. In particular, the ray tracing calculation shows that the mode converted energy is totally absorbed by the electrons close to the two-ion hybrid resonance. The generalised fast wave equation is solved to determine how much energy is lost from the fast wave, incident from the low field side, before it encounters the two-ion hybrid resonance. For comparable concentrations of the two ion species, the mode converted power can be separated from the power directly absorbed by the ions and electrons from the fast wave. This allows the conditions to be ascertained under which strong electron heating through mode conversion dominates the direct dissipation of the fast wave. (UK)

  1. Magnetohydrodynamic spin waves in degenerate electron-positron-ion plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Mushtaq, A. [TPPD, PINSTECH Nilore, 44000 Islamabad (Pakistan); National Center for Physics, Shahdrah Valley Road, 44000 Islamabad (Pakistan); Maroof, R.; Ahmad, Zulfiaqr [Institute of Physics and Electronics, University of Peshawar, 25000 Peshawar (Pakistan); Qamar, A. [National Center for Physics, Shahdrah Valley Road, 44000 Islamabad (Pakistan); Institute of Physics and Electronics, University of Peshawar, 25000 Peshawar (Pakistan)

    2012-05-15

    Low frequency magnetosonic waves are studied in magnetized degenerate electron-positron-ion plasmas with spin effects. Using the fluid equations of magnetoplasma with quantum corrections due to the Bohm potential, temperature degeneracy, and spin magnetization energy, a generalized dispersion relation for oblique magnetosonic waves is derived. Spin effects are incorporated via spin force and macroscopic spin magnetization current. For three different values of angle {theta}, the generalized dispersion relation is reduced to three different relations under the low frequency magnetohydrodynamic assumptions. It is found that the effect of quantum corrections in the presence of positron concentration significantly modifies the dispersive properties of these modes. The importance of the work relevant to compact astrophysical bodies is pointed out.

  2. Modulation instability of ion thermal waves in a pair-ion plasma containing charged dust impurities

    International Nuclear Information System (INIS)

    Sabry, R.

    2008-01-01

    Modulation instability of ion thermal waves (ITWs) is investigated in a plasma composed of positive and negative ions as well as a fraction of stationary charged (positive or negative) dust impurities. For this purpose, a linear dispersion relation and a nonlinear Schroedinger equation are derived. The latter admits localized envelope solitary wave solutions of bright (pulses) and dark (holes, voids) type. The envelope soliton depends on the intrinsic plasma parameters. It is found that modulation instability of ITWs is significantly affected by the presence of positively/negatively charged dust grains. The findings of this investigation should be useful in understanding the stable electrostatic wave packet acceleration mechanisms in pair-ion plasma, and also enhances our knowledge on the occurrence of instability associated to the existence of charged dust impurities in pair-ion plasmas. Our results should be of relevance for laboratory plasmas.

  3. Effect of Landau damping on kinetic Alfven and ion-acoustic solitary waves in a magnetized nonthermal plasma with warm ions

    International Nuclear Information System (INIS)

    Bandyopadhyay, Anup; Das, K.P.

    2002-01-01

    The evolution equations describing both kinetic Alfven wave and ion-acoustic wave in a nonthermal magnetized plasma with warm ions including weak nonlinearity and weak dispersion with the effect of Landau damping have been derived. These equations reduce to two coupled equations constituting the KdV-ZK (Korteweg-de Vries-Zakharov-Kuznetsov) equation for both kinetic Alfven wave and ion-acoustic wave, including an extra term accounting for the effect of Landau damping. When the coefficient of the nonlinear term of the evolution equation for ion-acoustic wave vanishes, the nonlinear behavior of ion-acoustic wave, including the effect of Landau damping, is described by two coupled equations constituting the modified KdV-ZK (MKdV-ZK) equation, including an extra term accounting for the effect of Landau damping. It is found that there is no effect of Landau damping on the solitary structures of the kinetic Alfven wave. Both the macroscopic evolution equations for the ion-acoustic wave admits solitary wave solutions, the former having a sech 2 profile and the latter having a sech profile. In either case, it is found that the amplitude of the ion-acoustic solitary wave decreases slowly with time

  4. Dispersion equations for field-aligned cyclotron waves in axisymmetric magnetospheric plasmas

    Directory of Open Access Journals (Sweden)

    N. I. Grishanov

    2006-03-01

    Full Text Available In this paper, we derive the dispersion equations for field-aligned cyclotron waves in two-dimensional (2-D magnetospheric plasmas with anisotropic temperature. Two magnetic field configurations are considered with dipole and circular magnetic field lines. The main contribution of the trapped particles to the transverse dielectric permittivity is estimated by solving the linearized Vlasov equation for their perturbed distribution functions, accounting for the cyclotron and bounce resonances, neglecting the drift effects, and assuming the weak connection of the left-hand and right-hand polarized waves. Both the bi-Maxwellian and bi-Lorentzian distribution functions are considered to model the ring current ions and electrons in the dipole magnetosphere. A numerical code has been developed to analyze the dispersion characteristics of electromagnetic ion-cyclotron waves in an electron-proton magnetospheric plasma with circular magnetic field lines, assuming that the steady-state distribution function of the energetic protons is bi-Maxwellian. As in the uniform magnetic field case, the growth rate of the proton-cyclotron instability (PCI in the 2-D magnetospheric plasmas is defined by the contribution of the energetic ions/protons to the imaginary part of the transverse permittivity elements. We demonstrate that the PCI growth rate in the 2-D axisymmetric plasmasphere can be significantly smaller than that for the straight magnetic field case with the same macroscopic bulk parameters.

  5. Observation of the backward electrostatic ion-cyclotron wave

    International Nuclear Information System (INIS)

    Goree, J.; Ono, M.; Wong, K.L.

    1985-01-01

    The backward branch of the electrostatic ion-cyclotron wave has been observed for the first time. The wave, which was driven by a phased antenna structure inserted in a neon plasma, exists in the parameter ranges 2T/sub i//m/sub i/ 2 or approx. =T/sub i/, and ω/sub p/i > Ω/sub i/. Double-tip probe interferometry data agree with the theoretical dispersion relation. The antenna couples into the wave more readily on the side of the antenna where it has its smallest wavenumber

  6. Investigation of electrostatic waves in the ion cyclotron range of frequencies in L-4 and ACT-1

    International Nuclear Information System (INIS)

    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 i ∼ 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. Dispersion relation for pure dust Bernstein waves in a non-Maxwellian magnetized dusty plasma

    International Nuclear Information System (INIS)

    Deeba, F.; Ahmad, Zahoor; Murtaza, G.

    2011-01-01

    Pure dust Bernstein waves are investigated using non-Maxwellian kappa and (r,q) distribution functions in a collisionless, uniform magnetized dusty plasma. Dispersion relations for both the distributions are derived by considering waves whose frequency is of the order of dust cyclotron frequency, and dispersion curves are plotted. It is observed that the propagation band for dust Bernstein waves is rather narrow as compared with that of the electron Bernstein waves. However, the band width increases for higher harmonics, for both kappa and (r,q) distributions. Effect of dust charge on dispersion curves is also studied, and one observes that with increasing dust charge, the dispersion curves shift toward the lower frequencies. Increasing the dust to ion density ratio ((n d0 /n i0 )) causes the dispersion curve to shift toward the higher frequencies. It is also found that for large values of spectral index kappa (κ), the dispersion curves approach to the Maxwellian curves. The (r,q) distribution approaches the kappa distribution for r = 0, whereas for r > 0, the dispersion curves show deviation from the Maxwellian curves as expected. Relevance of this work can be found in astrophysical plasmas, where non-Maxwellian velocity distributions as well as dust particles are commonly observed.

  8. Dispersion relation for pure dust Bernstein waves in a non-Maxwellian magnetized dusty plasma

    Energy Technology Data Exchange (ETDEWEB)

    Deeba, F. [National Tokamak Fusion Program, PAEC, P.O. Box 3329, Islamabad 44000 (Pakistan); Department of Physics, G.C. University, Lahore 54000 (Pakistan); Ahmad, Zahoor [National Tokamak Fusion Program, PAEC, P.O. Box 3329, Islamabad 44000 (Pakistan); Murtaza, G. [Salam Chair in Physics, G.C. University, Lahore 54000 (Pakistan)

    2011-07-15

    Pure dust Bernstein waves are investigated using non-Maxwellian kappa and (r,q) distribution functions in a collisionless, uniform magnetized dusty plasma. Dispersion relations for both the distributions are derived by considering waves whose frequency is of the order of dust cyclotron frequency, and dispersion curves are plotted. It is observed that the propagation band for dust Bernstein waves is rather narrow as compared with that of the electron Bernstein waves. However, the band width increases for higher harmonics, for both kappa and (r,q) distributions. Effect of dust charge on dispersion curves is also studied, and one observes that with increasing dust charge, the dispersion curves shift toward the lower frequencies. Increasing the dust to ion density ratio ((n{sub d0}/n{sub i0})) causes the dispersion curve to shift toward the higher frequencies. It is also found that for large values of spectral index kappa ({kappa}), the dispersion curves approach to the Maxwellian curves. The (r,q) distribution approaches the kappa distribution for r = 0, whereas for r > 0, the dispersion curves show deviation from the Maxwellian curves as expected. Relevance of this work can be found in astrophysical plasmas, where non-Maxwellian velocity distributions as well as dust particles are commonly observed.

  9. Nonlinear theory of ion-acoustic waves in an ideal plasma with degenerate electrons

    International Nuclear Information System (INIS)

    Dubinov, A. E.; Dubinova, A. A.

    2007-01-01

    A nonlinear theory is constructed that describes steady-state ion-acoustic waves in an ideal plasma in which the electron component is a degenerate Fermi gas and the ion component is a classical gas. The parameter ranges in which such a plasma can exist are determined, and dispersion relations for ion-acoustic waves are obtained that make it possible to find the linear ion-acoustic velocity. Analytic gas-dynamic models of ion sound are developed for a plasma with the ion component as a cold, an isothermal, or an adiabatic gas, and moreover, the solutions to the equations of all the models are brought to a quadrature form. Profiles of a subsonic periodic and a supersonic solitary wave are calculated, and the upper critical Mach numbers of a solitary wave are determined. For a plasma with cold ions, the critical Mach number is expressed by an explicit exact formula

  10. Linear electrostatic waves in a three-component electron-positron-ion plasma

    Energy Technology Data Exchange (ETDEWEB)

    Mugemana, A., E-mail: mugemanaa@gmail.com; Moolla, S. [School of Chemistry and Physics, University of KwaZulu-Natal, Durban 4000 (South Africa); Lazarus, I. J. [Department of Mathematics, Statistics and Physics, Durban University of Technology, Durban 4000 (South Africa)

    2014-12-15

    Analytical linear electrostatic waves in a magnetized three-component electron-positron-ion plasma are studied in the low-frequency limit. By using the continuity and momentum equations with Poisson's equation, the dispersion relation for the electron-positron-ion plasma consisting of cool ions, and hot Boltzmann electrons and positrons is derived. In the linear regime, the propagation of two possible modes and their evolution are studied. In the cases of parallel and perpendicular propagation, it is shown that these two possible modes are always stable. The present investigation contributes to nonlinear propagation of electrostatic waves in space and the laboratory.

  11. Ion-Beam-Excited Electrostatic Ion Cyclotron Waves

    DEFF Research Database (Denmark)

    Michelsen, Poul; Pécseli, Hans; Juul Rasmussen, Jens

    1976-01-01

    Self-excited electrostatic ion cyclotron waves were observed in an ion-beam-plasma system produced in a DP-operated Q-machine. The frequency of the waves showed the theoretically predicted variation with the magnetic field.......Self-excited electrostatic ion cyclotron waves were observed in an ion-beam-plasma system produced in a DP-operated Q-machine. The frequency of the waves showed the theoretically predicted variation with the magnetic field....

  12. Electron and ion Bernstein waves in Saturnian Magnetosphere

    Science.gov (United States)

    Bashir, M. F.; Waheed, A.; Ilie, R.; Naeem, I.; Maqsood, U.; Yoon, P. H.

    2017-12-01

    The study of Bernstein mode is presented in order to interpret the observed micro-structures (MIS) and banded emission (BEM) in the Saturnian magnetosphere. The general dispersion relation of Bernstein wave is derived using the Lerche-NewBerger sum rule for the kappa distribution function and further analyzed the both electron Bernstein (EB) and ion Bernstein (IB) waves. The observational data of particle measurements is obtained from the electron spectrometer (ELS) and the ion mass spectrometer (IMS), which are part of the Cassini Plasma Spectrometer (CAPS) instrument suite on board the Cassini spacecraft. For additional electron data, the measurements of Low Energy Magnetospheric Measurements System of the Magnetospheric Imaging Instrument (LEMMS /MIMI) are also utilized. The effect of kappa spectral index, density ratio (nohe/noce for EB and nohe/noi for IB) and the temperature ratio (The/Tce for EB and The/T(h,c)i for IB) on the dispersion properties are discussed employing the exact numerical analysis to explain the appearing of additional maxima/minima (points where the perpendicular group velocity vanishes, i.e., ∂w/∂k = 0) above/below the lower (for IB) and upper hybrid (EB) bands in the observation and their relation to the MIS and BED. The results of these waves may also be compared with the simulation results of Space Weather Modeling Framework (SWMF) .

  13. Drift waves and counter rotating vortices in pair-ion plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Haque, Q., E-mail: qamar_haque@hotmail.co [Theoretical Plasma Physics Division, PINSTECH P.O. Nilore, Islamabad (Pakistan)

    2010-07-19

    Linear dispersion relation has been found for drift and acoustic waves in pair-ion-electron plasmas. The stationary solution in the form of counter rotating vortices has been obtained in the presence of equilibrium potential profile. It is noticed that the speed of nonlinear structures is reduced with the increase of electrons concentration in pair-ion plasmas. Linear instability condition has also been found in the presence of shear flow. It is pointed out that the present results can be useful for future pair-ion plasma experiments.

  14. Wave dispersion relations in two-dimensional Yukawa systems

    International Nuclear Information System (INIS)

    Liu Yanhong; Liu Bin; Chen Yanping; Yang Size; Wang Long; Wang Xiaogang

    2003-01-01

    Collective modes in a two-dimensional Yukawa system are investigated by molecular dynamics simulation in a wide range of coupling parameter Γ and screening strength κ. The dispersion relations and sound speeds of the transverse and longitudinal waves obtained for hexagonal lattice are in agreement with the theoretical results. The negative dispersion of the longitudinal wave is demonstrated. Frequency gaps are found on the dispersion curves of the transverse wave due to scattering of the waves on lattice defects for proper values of Γ. The common frequency of transverse and longitudinal waves drops dramatically with the increasing screening strength κ

  15. Wave equation dispersion inversion using a difference approximation to the dispersion-curve misfit gradient

    KAUST Repository

    Zhang, Zhendong

    2016-07-26

    We present a surface-wave inversion method that inverts for the S-wave velocity from the Rayleigh wave dispersion curve using a difference approximation to the gradient of the misfit function. We call this wave equation inversion of skeletonized surface waves because the skeletonized dispersion curve for the fundamental-mode Rayleigh wave is inverted using finite-difference solutions to the multi-dimensional elastic wave equation. The best match between the predicted and observed dispersion curves provides the optimal S-wave velocity model. Our method can invert for lateral velocity variations and also can mitigate the local minimum problem in full waveform inversion with a reasonable computation cost for simple models. Results with synthetic and field data illustrate the benefits and limitations of this method. © 2016 Elsevier B.V.

  16. Ion Bernstein wave experiments on the Alcator C tokamak

    International Nuclear Information System (INIS)

    Moody, J.D.

    1988-09-01

    Ion Bernstein wave experiments are carried out on the Alcator C tokamak to study wave excitation, propagation, absorption, and plasma heating due to wave power absorption. It is shown that ion Bernstein wave power is coupled into the plasma and follows the expected dispersion relation. The antenna loading is maximized when the hydrogen second harmonic layer is positioned just behind the antenna. Plasma heating results at three values of the toroidal magnetic field are presented. Central ion temperature increases of ΔT/sub i//Ti /approx lt/ 0.1 and density increases Δn/n 6 s/sup /minus/1/ for plasmas within the density range 0.6 /times/ 10 20 m/sup /minus/3/ ≤ /bar n//sub e/ ≤ 4 /times/ 10 20 m/sup /minus/3/ and magnetic fields 2.4 ≥ ω/Ω/sub H/ ≥ 1.1. The density increases is usually accompanied by an improvement in the global particle confinement time relative to the Ohmic value. The ion heating rate is measured to be ΔT/sub i//P/sub rf/ ≅ 2-4.5 eV/kW at low densities. At higher densities /bar n//sub e/ ≤ 1.5 /times/ 10 20 m/sup /minus/3/ the ion heating rate dramatically decreases. It is shown that the decrease in the ion heating rate can be explained by the combined effects of wave scattering through the edge turbulence and the decreasing on energy confinement of these discharges with density. The effect of observed edge turbulence is shown to cause a broadening of the rf power deposition profile with increasing density. It is shown that the inferred value of the Ohmic ion thermal conduction, when compared to the Chang-Hinton neoclassical prediction, exhibits an increasing anomaly with increasing plasma density

  17. Linear and nonlinear ion-acoustic waves in nonrelativistic quantum plasmas with arbitrary degeneracy

    Science.gov (United States)

    Haas, Fernando; Mahmood, Shahzad

    2015-11-01

    Linear and nonlinear ion-acoustic waves are studied in a fluid model for nonrelativistic, unmagnetized quantum plasma with electrons with an arbitrary degeneracy degree. The equation of state for electrons follows from a local Fermi-Dirac distribution function and applies equally well both to fully degenerate and classical, nondegenerate limits. Ions are assumed to be cold. Quantum diffraction effects through the Bohm potential are also taken into account. A general coupling parameter valid for dilute and dense plasmas is proposed. The linear dispersion relation of the ion-acoustic waves is obtained and the ion-acoustic speed is discussed for the limiting cases of extremely dense or dilute systems. In the long-wavelength limit, the results agree with quantum kinetic theory. Using the reductive perturbation method, the appropriate Korteweg-de Vries equation for weakly nonlinear solutions is obtained and the corresponding soliton propagation is analyzed. It is found that soliton hump and dip structures are formed depending on the value of the quantum parameter for the degenerate electrons, which affect the phase velocities in the dispersive medium.

  18. Parametric instabilities of parallel propagating incoherent Alfven waves in a finite ion beta plasma

    International Nuclear Information System (INIS)

    Nariyuki, Y.; Hada, T.; Tsubouchi, K.

    2007-01-01

    Large amplitude, low-frequency Alfven waves constitute one of the most essential elements of magnetohydrodynamic (MHD) turbulence in the fast solar wind. Due to small collisionless dissipation rates, the waves can propagate long distances and efficiently convey such macroscopic quantities as momentum, energy, and helicity. Since loading of such quantities is completed when the waves damp away, it is important to examine how the waves can dissipate in the solar wind. Among various possible dissipation processes of the Alfven waves, parametric instabilities have been believed to be important. In this paper, we numerically discuss the parametric instabilities of coherent/incoherent Alfven waves in a finite ion beta plasma using a one-dimensional hybrid (superparticle ions plus an electron massless fluid) simulation, in order to explain local production of sunward propagating Alfven waves, as suggested by Helios/Ulysses observation results. Parameter studies clarify the dependence of parametric instabilities of coherent/incoherent Alfven waves on the ion and electron beta ratio. Parametric instabilities of coherent Alfven waves in a finite ion beta plasma are vastly different from those in the cold ions (i.e., MHD and/or Hall-MHD systems), even if the collisionless damping of the Alfven waves are neglected. Further, ''nonlinearly driven'' modulational instability is important for the dissipation of incoherent Alfven waves in a finite ion beta plasma regardless of their polarization, since the ion kinetic effects let both the right-hand and left-hand polarized waves become unstable to the modulational instability. The present results suggest that, although the antisunward propagating dispersive Alfven waves are efficiently dissipated through the parametric instabilities in a finite ion beta plasma, these instabilities hardly produce the sunward propagating waves

  19. Study on evaluation methods for Rayleigh wave dispersion characteristic

    Science.gov (United States)

    Shi, L.; Tao, X.; Kayen, R.; Shi, H.; Yan, S.

    2005-01-01

    The evaluation of Rayleigh wave dispersion characteristic is the key step for detecting S-wave velocity structure. By comparing the dispersion curves directly with the spectra analysis of surface waves (SASW) method, rather than comparing the S-wave velocity structure, the validity and precision of microtremor-array method (MAM) can be evaluated more objectively. The results from the China - US joint surface wave investigation in 26 sites in Tangshan, China, show that the MAM has the same precision with SASW method in 83% of the 26 sites. The MAM is valid for Rayleigh wave dispersion characteristic testing and has great application potentiality for site S-wave velocity structure detection.

  20. Bursts of electron waves modulated by oblique ion waves

    International Nuclear Information System (INIS)

    Boswell, R.W.

    1984-01-01

    Experimental evidence is presented which shows small packets of electron plasma waves modulated by large amplitude obliquely propagating non-linear ion plasma waves. Very often the whole system is modulated by an oscillation near the ion gyro frequency or its harmonics. The ion waves seem to be similar to those measured in the current carrying auroral plasma. These results suggest that the generation of ion and electron waves in the auroral plasma may be correlated

  1. Ion-acoustic nonlinear periodic waves in electron-positron-ion plasma

    International Nuclear Information System (INIS)

    Chawla, J. K.; Mishra, M. K.

    2010-01-01

    Ion-acoustic nonlinear periodic waves, namely, ion-acoustic cnoidal waves have been studied in electron-positron-ion plasma. Using reductive perturbation method and appropriate boundary condition for nonlinear periodic waves, the Korteweg-de Vries (KdV) equation is derived for the system. The cnoidal wave solution of the KdV equation is discussed in detail. It is found that the frequency of the cnoidal wave is a function of its amplitude. It is also found that the positron concentration modifies the properties of the ion-acoustic cnoidal waves. The existence regions for ion-acoustic cnoidal wave in the parameters space (p,σ), where p and σ are the positron concentration and temperature ratio of electron to positron, are discussed in detail. In the limiting case these ion-acoustic cnoidal waves reduce to the ion-acoustic soliton solutions. The effect of other parameters on the characteristics of the nonlinear periodic waves is also discussed.

  2. Ion Acoustic Waves in the Presence of Electron Plasma Waves

    DEFF Research Database (Denmark)

    Michelsen, Poul; Pécseli, Hans; Juul Rasmussen, Jens

    1977-01-01

    Long-wavelength ion acoustic waves in the presence of propagating short-wavelength electron plasma waves are examined. The influence of the high frequency oscillations is to decrease the phase velocity and the damping distance of the ion wave.......Long-wavelength ion acoustic waves in the presence of propagating short-wavelength electron plasma waves are examined. The influence of the high frequency oscillations is to decrease the phase velocity and the damping distance of the ion wave....

  3. Stability of the magnetosonic wave in a cometary multi-ion plasma

    Science.gov (United States)

    Sreekala, G.; Varghese, Anu; Jayakumar, Neethu; Michael, Manesh; Sebastian, Sijo; Venugopal, Chandu

    2017-05-01

    A generalized dispersion relation of the magnetosonic wave in a four component plasma consisting of electrons and hydrogen ions of solar origin and positively and negatively charged oxygen ions of cometary origin has been derived by using the Vlasov-Maxwell kinetic model. Parallel to the magnetic field, the hydrogen and electron components are modeled by a drifting Maxwellian distribution; perpendicular to the magnetic field, we use a loss cone type distribution obtained by the subtraction of two Maxwellian distributions having different temperatures. The effect of change in the drift velocity of streaming components and number densities and temperatures of each species in driving the instability has been analyzed both analytically and numerically. For typical parameters at comet Halley, we find that both positively and negatively charged oxygen ions can drive the wave unstable.

  4. Dispersive shock waves in systems with nonlocal dispersion of Benjamin-Ono type

    Science.gov (United States)

    El, G. A.; Nguyen, L. T. K.; Smyth, N. F.

    2018-04-01

    We develop a general approach to the description of dispersive shock waves (DSWs) for a class of nonlinear wave equations with a nonlocal Benjamin-Ono type dispersion term involving the Hilbert transform. Integrability of the governing equation is not a pre-requisite for the application of this method which represents a modification of the DSW fitting method previously developed for dispersive-hydrodynamic systems of Korteweg-de Vries (KdV) type (i.e. reducible to the KdV equation in the weakly nonlinear, long wave, unidirectional approximation). The developed method is applied to the Calogero-Sutherland dispersive hydrodynamics for which the classification of all solution types arising from the Riemann step problem is constructed and the key physical parameters (DSW edge speeds, lead soliton amplitude, intermediate shelf level) of all but one solution type are obtained in terms of the initial step data. The analytical results are shown to be in excellent agreement with results of direct numerical simulations.

  5. Experiments on ion-acoustic shock waves in a dusty plasma

    International Nuclear Information System (INIS)

    Nakamura, Y.

    2002-01-01

    Dust ion-acoustic shock waves have been investigated experimentally in a homogeneous unmagnetized dusty double-plasma device. An initial compressional wave with a ramp shape steepens to form oscillations at the leading part due to dispersion. The oscillation develops to a train of solitons when the plasma contains no dust grain. The wave becomes an oscillatory shock wave when the dust is mixed in the plasma and the density of the dust grains is smaller than a critical value. When the dust density is larger than the critical value, only steepening is observed at the leading part of the wave and a monotonic shock structure is observed. The velocity and width of the shock waves are measured and compared with results of numerical integrations of the modified Korteweg-de Vries-Burgers equation

  6. Dispersion relations of density fluctuations observed by heavy ion beam probe in the TEXT tokamak

    International Nuclear Information System (INIS)

    Ross, D.W.

    1990-09-01

    Wave numbers as functions of frequency for density fluctuations in the core of the TEXT tokamak are measured in Heavy Ion Beam Probe experiments by analyzing the relative phases of signals originating from nearby points in the plasma. The adjacent points are typically 2 cm apart, with their relative orientation (δr, δθ) depending on position (r,θ). for angular frequencies ω ≤ 10 6 /s the signals are quite coherent, leading to reasonably well-defined ''dispersion relations.'' These do not correspond to known modes of the drift wave type, i.e., ballooning or slab-like electron drift waves or ion temperature gradient modes. The effect of finite sample volume size does not significantly alter this conclusion. 25 refs., 6 figs., 3 tabs

  7. On the development and evolution of nonlinear ion acoustic wave packets

    Directory of Open Access Journals (Sweden)

    A. M. Hamza

    2005-09-01

    Full Text Available A simple model of ion fluctuations (ion acoustic and ion cyclotron fluctuations for example driven by an electron current which leads to intermittent fluctuations when the linear growth rate exceeds the wave packet dispersion rate is analized. The normalized fluctuation amplitude eφ0/T can be much larger than the mass ratio (me/mi level predicted by the conventional quasilinear theory or Manheimer's theory (see references in this document, and where φ0 represents the amplitude of the main peak of the ion fluctuations. Although the ion motion is linear, intermittency is produced by the strong nonlinear electron response, which causes the electron momentum input to the ion fluctuations to be spatially localized. We treat the 1-D case because it is especially simple from an intuitive and analytical point of view, but it is readily apparent and one can put forward the conjecture that the effect occurs in a three dimensional magnetized plasma. The 1-D analysis, as shown in this manuscript will clearly help identify the subtle difference between turbulence as conventionally understood and intermittency as it occurs in space and laboratory plasmas. Keywords. Meteorology and atmospheric dynamics (Turbulence – Ionosphere (Wave-particles interactions – Space plasma physics (Waves and instabilities

  8. Dispersion characteristics of a two-beam electron-ion system in a magnetic field

    International Nuclear Information System (INIS)

    Kapchinskij, M.I.; Rozanov, N.E.

    1982-01-01

    Without an assumption of the problem potentiality the dispersion properties of a two-beam system important for the realization of the autoresonance method of the acceleration are investigated for the different configurations of an electron flow and arbitrary radii of an ion beam. Two models are used. In the first the ion beam is considered a homogeneous dielectric medium of low density, which permits to apply to the problem the method of perturbations and examine both continuous and thin-wall tubular electron beams. The second model based on an assumption of the self-similarity of beam density change permits to describe ion instabilities of both the cyclotron and Langmuir waves of the electron beam in the quasistatic long-wave limit. Comparison of the results shows that both approaches in the longwave limit give the same qualitative dependence of instability increments on the system parameters and the complicated qualitative dependence. It is shown that for the purposes of the collective ion acceleration it is necessary to decrease the ion beam radius, as it permits to avoid the development of stray instabilities [ru

  9. Wall effects on the propagation of compressional Alfven waves in a cylindrical plasma with two-ion species

    International Nuclear Information System (INIS)

    Akiyama, H.; Hayler, M.O.; Kristiansen, M.

    1985-01-01

    The dispersion relations for the compressional Alfven waves in a two-ion species plasma of deuterium and hydrogen are calculated for a configuration which includes a vacuum layer between the cylindrical plasma and the conducting wall. The presence of the vacuum layer strongly affects the propagation of the compressional Alfven wave, permitting some branches to propagate and penetrate the plasma column over most frequencies in the ion-cyclotron range. Basic Alfven-wave propagation and heating experiments in two-ion species consequently should be possible using tokamak and mirror devices with minor radii smaller than the Alfven wavelength

  10. Response of thermal ions to electromagnetic ion cyclotron waves

    Science.gov (United States)

    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.

  11. Travelling wave solutions of generalized coupled Zakharov–Kuznetsov and dispersive long wave equations

    Directory of Open Access Journals (Sweden)

    M. Arshad

    Full Text Available In this manuscript, we constructed different form of new exact solutions of generalized coupled Zakharov–Kuznetsov and dispersive long wave equations by utilizing the modified extended direct algebraic method. New exact traveling wave solutions for both equations are obtained in the form of soliton, periodic, bright, and dark solitary wave solutions. There are many applications of the present traveling wave solutions in physics and furthermore, a wide class of coupled nonlinear evolution equations can be solved by this method. Keywords: Traveling wave solutions, Elliptic solutions, Generalized coupled Zakharov–Kuznetsov equation, Dispersive long wave equation, Modified extended direct algebraic method

  12. Coupled ion acoustic and drift waves in magnetized superthermal electron-positron-ion plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Adnan, Muhammad; Qamar, Anisa [Institute of Physics and Electronics, University of Peshawar, Peshawar 25000 (Pakistan); National Center for Physics, Quaid-i-Azam University Campus, Shahdra Valley Road, Islamabad 44000 (Pakistan); Mahmood, S. [National Center for Physics, Quaid-i-Azam University Campus, Shahdra Valley Road, Islamabad 44000 (Pakistan); Theoretical Physics Division, PINSTECH P.O. Nilore Islamabad 44000 (Pakistan); Physics Institute, Federal University of Rio Grande do Sul (UFRGS), 915051-970, Porto Alegre, RS (Brazil)

    2014-09-15

    Linear and nonlinear coupled drift-ion acoustic waves are investigated in a nonuniform magnetoplasma having kappa distributed electrons and positrons. In the linear regime, the role of kappa distribution and positron content on the dispersion relation has been highlighted; it is found that strong superthermality (low value of κ) and addition of positrons lowers the phase velocity via decreasing the fundamental scalelengths of the plasmas. In the nonlinear regime, first, coherent nonlinear structure in the form of dipoles and monopoles are obtained and the boundary conditions (boundedness) in the context of superthermality and positron concentrations are discussed. Second, in case of scalar nonlinearity, a Korteweg–de Vries-type equation is obtained, which admit solitary wave solution. It is found that both compressive and rarefactive solitons are formed in the present model. The present work may be useful to understand the low frequency electrostatic modes in inhomogeneous electron positron ion plasmas, which exist in astrophysical plasma situations such as those found in the pulsar magnetosphere.

  13. Coupled ion acoustic and drift waves in magnetized superthermal electron-positron-ion plasmas

    Science.gov (United States)

    Adnan, Muhammad; Mahmood, S.; Qamar, Anisa

    2014-09-01

    Linear and nonlinear coupled drift-ion acoustic waves are investigated in a nonuniform magnetoplasma having kappa distributed electrons and positrons. In the linear regime, the role of kappa distribution and positron content on the dispersion relation has been highlighted; it is found that strong superthermality (low value of κ) and addition of positrons lowers the phase velocity via decreasing the fundamental scalelengths of the plasmas. In the nonlinear regime, first, coherent nonlinear structure in the form of dipoles and monopoles are obtained and the boundary conditions (boundedness) in the context of superthermality and positron concentrations are discussed. Second, in case of scalar nonlinearity, a Korteweg-de Vries-type equation is obtained, which admit solitary wave solution. It is found that both compressive and rarefactive solitons are formed in the present model. The present work may be useful to understand the low frequency electrostatic modes in inhomogeneous electron positron ion plasmas, which exist in astrophysical plasma situations such as those found in the pulsar magnetosphere.

  14. Auroral ion beams and ion acoustic wave generation by fan instability

    Energy Technology Data Exchange (ETDEWEB)

    Vaivads, A

    1996-04-01

    Satellite observations indicate that efficient energy transport among various plasma particles and between plasma waves and plasma particles is taking place in auroral ion beam regions. These observations show that two characteristic wave types are associated with the auroral ion beam regions: electrostatic hydrogen cyclotron waves with frequencies above hydrogen gyrofrequency, and low frequency waves with frequencies below hydrogen gyrofrequency. We speculate that the low frequency waves can be ion acoustic waves generated through the fan instability. The presence of a cold background ion component is necessary for the onset of this instability. A cold ion component has been directly observed and has been indirectly suggested from observations of solitary wave structures. The wave-particle interaction during the development of the fan instability results in an efficient ion beam heating in the direction perpendicular to the ambient magnetic field. The fan instability development and the ion beam heating is demonstrated in a numerical particle simulation. 23 refs, 16 figs.

  15. Wave-equation dispersion inversion of surface waves recorded on irregular topography

    KAUST Repository

    Li, Jing; Schuster, Gerard T.; Lin, Fan-Chi; Alam, Amir

    2017-01-01

    Significant topographic variations will strongly influence the amplitudes and phases of propagating surface waves. Such effects should be taken into account, otherwise the S-velocity model inverted from the Rayleigh dispersion curves will contain significant inaccuracies. We now show that the recently developed wave-equation dispersion inversion (WD) method naturally takes into account the effects of topography to give accurate S-velocity tomograms. Application of topographic WD to demonstrates that WD can accurately invert dispersion curves from seismic data recorded over variable topography. We also apply this method to field data recorded on the crest of mountainous terrain and find with higher resolution than the standard WD tomogram.

  16. Wave-equation dispersion inversion of surface waves recorded on irregular topography

    KAUST Repository

    Li, Jing

    2017-08-17

    Significant topographic variations will strongly influence the amplitudes and phases of propagating surface waves. Such effects should be taken into account, otherwise the S-velocity model inverted from the Rayleigh dispersion curves will contain significant inaccuracies. We now show that the recently developed wave-equation dispersion inversion (WD) method naturally takes into account the effects of topography to give accurate S-velocity tomograms. Application of topographic WD to demonstrates that WD can accurately invert dispersion curves from seismic data recorded over variable topography. We also apply this method to field data recorded on the crest of mountainous terrain and find with higher resolution than the standard WD tomogram.

  17. Ion Bernstein wave heating research

    International Nuclear Information System (INIS)

    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 (ω/k perpendicular ∼ V Ti much-lt V α ) greatly reduces the otherwise serious wave absorption by the 3.5 MeV fusion α-particles. In addition, the property of IBW's that k perpendicular ρ i ∼ 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

  18. Nonlinear structure formation in ion-temperature-gradient driven drift waves in pair-ion plasma with nonthermal electron distribution

    Science.gov (United States)

    Razzaq, Javaria; Haque, Q.; Khan, Majid; Bhatti, Adnan Mehmood; Kamran, M.; Mirza, Arshad M.

    2018-02-01

    Nonlinear structure formation in ion-temperature-gradient (ITG) driven waves is investigated in pair-ion plasma comprising ions and nonthermal electrons (kappa, Cairns). By using the transport equations of the Braginskii model, a new set of nonlinear equations are derived. A linear dispersion relation is obtained and discussed analytically as well as numerically. It is shown that the nonthermal population of electrons affects both the linear and nonlinear characteristics of the ITG mode in pair-ion plasma. This work will be useful in tokamaks and stellarators where non-Maxwellian population of electrons may exist due to resonant frequency heating, electron cyclotron heating, runaway electrons, etc.

  19. Dispersive Evolution of Nonlinear Fast Magnetoacoustic Wave Trains

    Energy Technology Data Exchange (ETDEWEB)

    Pascoe, D. J.; Goddard, C. R.; Nakariakov, V. M., E-mail: D.J.Pascoe@warwick.ac.uk [Centre for Fusion, Space and Astrophysics, Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom)

    2017-10-01

    Quasi-periodic rapidly propagating wave trains are frequently observed in extreme ultraviolet observations of the solar corona, or are inferred by the quasi-periodic modulation of radio emission. The dispersive nature of fast magnetohydrodynamic waves in coronal structures provides a robust mechanism to explain the detected quasi-periodic patterns. We perform 2D numerical simulations of impulsively generated wave trains in coronal plasma slabs and investigate how the behavior of the trapped and leaky components depend on the properties of the initial perturbation. For large amplitude compressive perturbations, the geometrical dispersion associated with the waveguide suppresses the nonlinear steepening for the trapped wave train. The wave train formed by the leaky components does not experience dispersion once it leaves the waveguide and so can steepen and form shocks. The mechanism we consider can lead to the formation of multiple shock fronts by a single, large amplitude, impulsive event and so can account for quasi-periodic features observed in radio spectra.

  20. Model-based dispersive wave processing: A recursive Bayesian solution

    International Nuclear Information System (INIS)

    Candy, J.V.; Chambers, D.H.

    1999-01-01

    Wave propagation through dispersive media represents a significant problem in many acoustic applications, especially in ocean acoustics, seismology, and nondestructive evaluation. In this paper we propose a propagation model that can easily represent many classes of dispersive waves and proceed to develop the model-based solution to the wave processing problem. It is shown that the underlying wave system is nonlinear and time-variable requiring a recursive processor. Thus the general solution to the model-based dispersive wave enhancement problem is developed using a Bayesian maximum a posteriori (MAP) approach and shown to lead to the recursive, nonlinear extended Kalman filter (EKF) processor. The problem of internal wave estimation is cast within this framework. The specific processor is developed and applied to data synthesized by a sophisticated simulator demonstrating the feasibility of this approach. copyright 1999 Acoustical Society of America.

  1. Generalized dispersive wave emission in nonlinear fiber optics.

    Science.gov (United States)

    Webb, K E; Xu, Y Q; Erkintalo, M; Murdoch, S G

    2013-01-15

    We show that the emission of dispersive waves in nonlinear fiber optics is not limited to soliton-like pulses propagating in the anomalous dispersion regime. We demonstrate, both numerically and experimentally, that pulses propagating in the normal dispersion regime can excite resonant dispersive radiation across the zero-dispersion wavelength into the anomalous regime.

  2. Mode conversion of lower hybrid waves at high ion cyclotron harmonics. Appendix F

    International Nuclear Information System (INIS)

    Swanson, D.G.; Cho, S.

    1985-05-01

    The problem of ion cyclotron harmonic absorption for a lower hybrid wave is shown to be a mode conversion problem. A new form of the dispersion relation is developed and then expanded to get a differential equation identical to that for the second harmonic problem. The validity of this model is restricted to the region far from the lower hybrid resonance layer. It is shown that mode couplings occur among the incident cold wave and two other waves, and the tunneling factor becomes singular there

  3. Characteristics of the resonant instability of surface electrostatic-ion-cyclotron waves in a semi-bounded warm magnetized dusty plasma

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Woo-Pyo [Department of Electronics Engineering, Catholic University of Daegu, Hayang, 38430 (Korea, Republic of); Jung, Young-Dae, E-mail: ydjung@hanyang.ac.kr [Department of Applied Physics and Department of Bionanotechnology, Hanyang University, Ansan, Kyunggi-Do 15588 (Korea, Republic of); Department of Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute, 110 8th Street, Troy, NY 12180-3590 (United States)

    2016-03-11

    The influence of magnetic field and dust rotation on the resonant instability of surface electrostatic-ion-cyclotron wave is kinetically investigated in a semi-bounded warm magnetized dusty plasma. The dispersion relation and the temporal growth rate of the surface electrostatic-ion-cyclotron wave are derived by the specular-reflection boundary condition including the magnetic field and dust rotation effects. It is found that the instability domain decreases with an increase of the rotation frequency of elongated dust grain. It is also found that the dependence of the propagation wave number on the temporal growth rate is more significant for small ion cyclotron frequencies. In addition, it is shown that the scaled growth rate increases with an increase of the strength of magnetic field. The variation of the domain and magnitude of temporal growth rate due to the change of plasma parameters is also discussed. - Highlights: • The resonant instability of surface electrostatic-ion-cyclotron wave is investigated in a semi-bounded magnetized dusty plasma. • The dispersion relation and the temporal growth rate are derived by the specular-reflection condition. • The influence of magnetic field and dust rotation on the resonant instability is discussed.

  4. Robust Imaging Methodology for Challenging Environments: Wave Equation Dispersion Inversion of Surface Waves

    KAUST Repository

    Li, Jing

    2017-12-22

    A robust imaging technology is reviewed that provide subsurface information in challenging environments: wave-equation dispersion inversion (WD) of surface waves for the shear velocity model. We demonstrate the benefits and liabilities of the method with synthetic seismograms and field data. The benefits of WD are that 1) there is no layered medium assumption, as there is in conventional inversion of dispersion curves, so that the 2D or 3D S-velocity model can be reliably obtained with seismic surveys over rugged topography, and 2) WD mostly avoids getting stuck in local minima. The synthetic and field data examples demonstrate that WD can accurately reconstruct the S-wave velocity distributions in laterally heterogeneous media if the dispersion curves can be identified and picked. The WD method is easily extended to anisotropic media and the inversion of dispersion curves associated with Love wave. The liability is that is almost as expensive as FWI and only recovers the Vs distribution to a depth no deeper than about 1/2~1/3 wavelength.

  5. Wave power balance in resonant dissipative media with spatial and temporal dispersion

    International Nuclear Information System (INIS)

    Tokman, M.D.; Gavrilova, M.A.; Westerhof, E. . www.rijnh.nl

    2003-01-01

    A power balance for waves in resonant dissipative media is formulated, which generalizes well-known expressions for dielectric wave energy density, wave energy flux, and dissipated power density. The identification of the different terms with wave energy density and flux remains only phenomenological. The result is better viewed as an equation for the evolution of wave intensity. In that form, its consequences are discussed in particular in relation to anomalous dispersion. A discrimination is made between boundary and initial value problems. For boundary value problems, anomalous dispersion is shown not to lead to unphysical results. In contrast, for initial value problems the solution for the evolution of wave intensity is shown to be at fault in the case of anomalous dispersion. Further illustration is provided by consideration of wave dispersion in a medium of charged harmonic oscillators and of ordinary-mode dispersion in plasma. Both are characterized by anomalous dispersion and show marked differences in the solutions of the dispersion relation solved either for complex wave vector at real frequency, k(ω) (applicable to boundary value problems), or for complex frequency at real wave vector ω(k) (applicable to initial value problems). (author)

  6. Optimized nonlinear inversion of surface-wave dispersion data

    International Nuclear Information System (INIS)

    Raykova, Reneta B.

    2014-01-01

    A new code for inversion of surface wave dispersion data is developed to obtain Earth’s crustal and upper mantle velocity structure. The author developed Optimized Non–Linear Inversion ( ONLI ) software, based on Monte-Carlo search. The values of S–wave velocity VS and thickness h for a number of horizontal homogeneous layers are parameterized. Velocity of P–wave VP and density ρ of relevant layers are calculated by empirical or theoretical relations. ONLI explores parameters space in two modes, selective and full search, and the main innovation of software is evaluation of tested models. Theoretical dispersion curves are calculated if tested model satisfied specific conditions only, reducing considerably the computation time. A number of tests explored impact of parameterization and proved the ability of ONLI approach to deal successfully with non–uniqueness of inversion problem. Key words: Earth’s structure, surface–wave dispersion, non–linear inversion, software

  7. Preferential heating of oxygen 5{sup +} ions by finite-amplitude oblique Alfvén waves

    Energy Technology Data Exchange (ETDEWEB)

    Maneva, Yana G.; Poedts, Stefaan [Centre for mathematical Plasma Astrophysics, KU Leuven, B-3001 Leuven (Belgium); Viñas, Adolfo [NASA Goddard Space Flight Center, Heliophysics Science Division, Greenbelt, 20771 MD (United States); Araneda, Jaime [Departamento de Física, Universidad de Concepción, Casilla 160 - C, Concepción (Chile)

    2016-03-25

    Minor ions in the fast solar wind are known to have higher temperatures and to flow faster than protons in the interplanetary space. In this study we combine previous research on parametric instability theory and 2.5D hybrid simulations to study the onset of preferential heating of Oxygen 5{sup +} ions by large-scale finite-amplitude Alfvén waves in the collisionless fast solar wind. We consider initially non-drifting isotropic multi-species plasma, consisting of isothermal massless fluid electrons, kinetic protons and kinetic Oxygen 5{sup +} ions. The external energy source for the plasma heating and energization are oblique monochromatic Alfvén-cyclotron waves. The waves have been created by rotating the direction of initial parallel pump, which is a solution of the multi-fluid plasma dispersion relation. We consider propagation angles θ ≤ 30°. The obliquely propagating Alfvén pump waves lead to strong diffusion in the ion phase space, resulting in highly anisotropic heavy ion velocity distribution functions and proton beams. We discuss the application of the model to the problems of preferential heating of minor ions in the solar corona and the fast solar wind.

  8. Dispersion of acoustic surface waves by velocity gradients

    Science.gov (United States)

    Kwon, S. D.; Kim, H. C.

    1987-10-01

    The perturbation theory of Auld [Acoustic Fields and Waves in Solids (Wiley, New York, 1973), Vol. II, p. 294], which describes the effect of a subsurface gradient on the velocity dispersion of surface waves, has been modified to a simpler form by an approximation using a newly defined velocity gradient for the case of isotropic materials. The modified theory is applied to nitrogen implantation in AISI 4140 steel with a velocity gradient of Gaussian profile, and compared with dispersion data obtained by the ultrasonic right-angle technique in the frequency range from 2.4 to 14.8 MHz. The good agreement between experiments and our theory suggests that the compound layer in the subsurface region plays a dominant role in causing the dispersion of acoustic surface waves.

  9. Wave equation dispersion inversion using a difference approximation to the dispersion-curve misfit gradient

    KAUST Repository

    Zhang, Zhendong; Schuster, Gerard T.; Liu, Yike; Hanafy, Sherif M.; Li, Jing

    2016-01-01

    We present a surface-wave inversion method that inverts for the S-wave velocity from the Rayleigh wave dispersion curve using a difference approximation to the gradient of the misfit function. We call this wave equation inversion of skeletonized

  10. P-wave dispersion: relationship to left ventricular function in sickle cell anaemia.

    Science.gov (United States)

    Oguanobi, N I; Onwubere, B J; Ike, S O; Anisiuba, B C; Ejim, E C; Ibegbulam, O G

    2011-01-01

    The prognostic implications of P-wave dispersion in patients with a variety of cardiac disease conditions are increasingly being recognised. The relationship between P-wave dispersion and left ventricular function in sickle cell anaemia is unknown. This study was aimed at evaluating the relationship between P-wave dispersion and left ventricular function in adult Nigerian sickle cell anaemia patients. Between February and August 2007, a total of 62 sickle cell anaemia patients (aged 18-44 years; mean 28.27 ± 5.58) enrolled in the study. These were drawn from patients attending the adult sickle cell clinic of the University of Nigeria Teaching Hospital, Ituku-Ozalla, Enugu. An equal number of age- and gender-matched normal subjects served as controls. All the participants were evaluated with electrocardiography and echocardiography. P-wave dispersion was defined as the difference between the maximum and minimum P-wave duration measured in a 12-lead electrocardiogram. P-wave duration and P-wave dispersion were significantly higher in patients than in controls. Significant correlation was demonstrated between P-wave dispersion and age in the patients (r = 0.387; p = 0.031). A comparison of subsets of sickle cell anaemia patients and controls with comparable haematocrit values (30-35%) showed significantly higher P-wave duration and P-wave dispersion in the patients than in the controls. The P-wave duration in patients and controls, respectively, was 111.10 ± 14.53 ms and 89.14 ± 16.45 ms (t = 3.141; p = 0.006). P-wave dispersion was 64.44 ± 15.86 ms in the patients and 36.43 ± 10.35 ms in the controls (t = 2.752; p = 0.013). Significant negative correlation was found between P-wave dispersion and left ventricular transmitral E/A ratio (r = -0.289; p = 0.023). These findings suggest that P-wave dispersion could be useful in the evaluation of sickle cell patients with left ventricular diastolic dysfunction. Further prospective studies are recommended to evaluate

  11. Nonlinear dust-ion-acoustic waves in a multi-ion plasma with ...

    Indian Academy of Sciences (India)

    The basic features of such dust-ion-acoustic solitary and shock waves have been ... ion plasmas because of its vital role in understanding different types of ... cannot support the usual ion-acoustic waves, but can support the DIA waves of ...

  12. Dispersive shock waves in nonlinear and atomic optics

    Directory of Open Access Journals (Sweden)

    Kamchatnov Anatoly

    2017-01-01

    Full Text Available A brief review is given of dispersive shock waves observed in nonlinear optics and dynamics of Bose-Einstein condensates. The theory of dispersive shock waves is developed on the basis of Whitham modulation theory for various situations taking place in these two fields. In particular, the full classification is established for types of wave structures evolving from initial discontinuities for propagation of long light pulses in fibers with account of steepening effect and for dynamics of the polarization mode in two-component Bose-Einstein condensates.

  13. Nonlinear waves in plasma with negative ion

    International Nuclear Information System (INIS)

    Saito, Maki; Watanabe, Shinsuke; Tanaca, Hiroshi.

    1984-01-01

    The propagation of nonlinear ion wave is investigated theoretically in a plasma with electron, positive ion and negative ion. The ion wave of long wavelength is described by a modified K-dV equation instead of a K-dV equation when the nonlinear coefficient of the K-dV equation vanishes at the critical density of negative ion. In the vicinity of the critical density, the ion wave is described by a coupled K-dV and modified K-dV equation. The transition from a compressional soliton to a rarefactive soliton and vice versa are examined by the coupled equation as a function of the negative ion density. The ion wave of short wavelength is described by a nonlinear Schroedinger equation. In the plasma with a negative ion, the nonlinear coefficient of the nonlinear Schroedinger equation changes the sign and the ion wave becomes modulationally unstable. (author)

  14. PARTICLE SCATTERING OFF OF RIGHT-HANDED DISPERSIVE WAVES

    Energy Technology Data Exchange (ETDEWEB)

    Schreiner, C.; Kilian, P.; Spanier, F., E-mail: cschreiner@astro.uni-wuerzburg.de [Centre for Space Research, North-West University, 2520 Potchefstroom (South Africa)

    2017-01-10

    Resonant scattering of fast particles off low frequency plasma waves is a major process determining transport characteristics of energetic particles in the heliosphere and contributing to their acceleration. Usually, only Alfvén waves are considered for this process, although dispersive waves are also present throughout the heliosphere. We investigate resonant interaction of energetic electrons with dispersive, right-handed waves. For the interaction of particles and a single wave a variable transformation into the rest frame of the wave can be performed. Here, well-established analytic models derived in the framework of magnetostatic quasi-linear theory can be used as a reference to validate simulation results. However, this approach fails as soon as several dispersive waves are involved. Based on analytic solutions modeling the scattering amplitude in the magnetostatic limit, we present an approach to modify these equations for use in the plasma frame. Thereby we aim at a description of particle scattering in the presence of several waves. A particle-in-cell code is employed to study wave–particle scattering on a micro-physically correct level and to test the modified model equations. We investigate the interactions of electrons at different energies (from 1 keV to 1 MeV) and right-handed waves with various amplitudes. Differences between model and simulation arise in the case of high amplitudes or several waves. Analyzing the trajectories of single particles we find no microscopic diffusion in the case of a single plasma wave, although a broadening of the particle distribution can be observed.

  15. Kinetic Alfven wave with density variation and loss-cone distribution function of multi-ions in PSBL region

    Science.gov (United States)

    Tamrakar, Radha; Varma, P.; Tiwari, M. S.

    2018-05-01

    Kinetic Alfven wave (KAW) generation due to variation of loss-cone index J and density of multi-ions (H+, He+ and O+) in the plasma sheet boundary layer region (PSBL) is investigated. Kinetic approach is used to derive dispersion relation of wave using Vlasov equation. Variation of frequency with respect to wide range of k⊥ρi (where k⊥ is wave vector across the magnetic field, ρi is gyroradius of ions and i denotes H+, He+ and O+ ions) is analyzed. It is found that each ion gyroradius and number density shows different effect on wave generation with varying width of loss-cone. KAW is generated with multi-ions (H+, He+ and O+) over wide regime for J=1 and shows dissimilar effect for J=2. Frequency is reduced with increasing density of gyrating He+ and O+ ions. Wave frequency is obtained within the reported range which strongly supports generation of kinetic Alfven waves. A sudden drop of frequency is also observed for H+ and He+ ion which may be due to heavy penetration of these ions through the loss-cone. The parameters of PSBL region are used for numerical calculation. The application of these results are in understanding the effect of gyrating multi-ions in transfer of energy and Poynting flux losses from PSBL region towards ionosphere and also describing the generation of aurora.

  16. Dispersion of extensional waves in fluid-saturated porous cylinders at ultrasonic frequencies

    International Nuclear Information System (INIS)

    Berryman, J.G.

    1983-01-01

    Ultrasonic dispersion of extensional waves in fluid-saturated porous cylinders is studied by analyzing generalized Pochhammer equations derived using Biot's theory. Cases with open-pore surface and closed-pore surface boundary conditions are considered. For both cases, the dispersion of the fast extensional wave does not differ much qualitatively from the dispersion expected for extensional waves in isotropic elastic cylinders. A slow extensional wave propagates in the case with a closed-pore surface but not in the case with an open-pore surface. The propagating slow wave has very weak dispersion and its speed is always lower than, but close to, the bulk slow wave speed

  17. Modeling of Rayleigh wave dispersion in Iberia

    Directory of Open Access Journals (Sweden)

    José Badal

    2011-01-01

    Full Text Available Phase and group velocities of 15–70 s Rayleigh waves propagating across the Iberian Peninsula have been transformed into local dispersion curves by linear inversion of travel times. The procedure permits that the waveform dispersion to be obtained as a continuous period-dependent velocity function at grid points belonging to the area probed by the waves, thus providing phase- and group-velocity contour maps for several periods within the interval of interest. The regionalization process rests on a homogeneous initial data set in which the number of observations remains almost constant for all periods of reference. Damped least-squares inversion of the local dispersion curves for shear-wave velocity structure is performed to obtain depth-dependent S-wave velocity profiles at the grid points covering the model region. The reliability of the results should improve significantly owing to the use of phase and group velocities simultaneously. On this basis, we have built horizontal depth sections that give an updated view of the seismic velocity structure of the peninsula at lithospheric and upper mantle depths (20–200 km. After averaging all the pure-path S-wave velocities previously determined at each grid point, the velocity-depth models so obtained for major tectonic units allow the comparison between the Hercynian basement and other areas of Mesozoic folding and Tertiary basins.

  18. Wave modulation in a nonlinear dispersive medium

    International Nuclear Information System (INIS)

    Kim, Y.C.; Khadra, L.; Powers, E.J.

    1980-01-01

    A model describing the simultaneous amplitude and phase modulation of a carrier wave propagating in a nonlinear dispersive medium is developed in terms of nonlinear wave-wave interactions between the sidebands and a low frequency wave. It is also shown that the asymmetric distribution of sidebands is determined by the wavenumber dependence of the coupling coefficient. Digital complex demodulation techniques are used to study modulated waves in a weakly ionized plasma and the experimental results support the analytical model

  19. Large Amplitude Low Frequency Waves in a Magnetized Nonuniform Electron-Positron-Ion Plasma

    Institute of Scientific and Technical Information of China (English)

    Q. Haque; H. Saleem

    2004-01-01

    @@ It is shown that the large amplitude low-frequency electromagnetic drift waves in electron-positron-ion plasmas might give rise to dipolar vortices. A linear dispersion relation of several coupled electrostatic and electromagnetic low-frequency modes is obtained. The relevance of this work to both laboratory and astrophysical situations is pointed out.

  20. Competition and Dispersal in Predator-Prey Waves

    NARCIS (Netherlands)

    Savill, N.J.; Hogeweg, P.

    1998-01-01

    Dispersing predators and prey can exhibit complex spatio-temporal wave-like patterns if the interactions between them cause oscillatory dynamics. We study the effect of these predator- prey density waves on the competition between prey populations and between predator popu- lations with different

  1. Utilization of multimode Love wave dispersion curve inversion for geotechnical site investigation

    International Nuclear Information System (INIS)

    Hamimu, La; Nawawi, Mohd; Safani, Jamhir

    2011-01-01

    Inversion codes based on a modified genetic algorithm (GA) have been developed to invert multimode Love wave dispersion curves. The multimode Love wave dispersion curves were synthesized from the profile representing shear-wave velocity reversal using a full SH (shear horizontal) waveform. In this study, we used a frequency–slowness transform to extract the dispersion curve from the full SH waveform. Dispersion curves overlain in dispersion images were picked manually. These curves were then inverted using the modified GA. To assess the accuracy of the inversion results, differences between the true and inverted shear-wave velocity profile were quantified in terms of shear-wave velocity and thickness errors, E S and E H . Our numerical modeling showed that the inversion of multimode dispersion curves can significantly provide the better assessment of a shear-wave velocity structure, especially with a velocity reversal profile at typical geotechnical site investigations. This approach has been applied on field data acquired at a site in Niigata prefecture, Japan. In these field data, our inversion results show good agreement between the calculated and experimental dispersion curves and accurately detect low velocity layer targets

  2. Ion stochastic heating by obliquely propagating magnetosonic waves

    International Nuclear Information System (INIS)

    Gao Xinliang; Lu Quanming; Wu Mingyu; Wang Shui

    2012-01-01

    The ion motions in obliquely propagating Alfven waves with sufficiently large amplitudes have already been studied by Chen et al.[Phys. Plasmas 8, 4713 (2001)], and it was found that the ion motions are stochastic when the wave frequency is at a fraction of the ion gyro-frequency. In this paper, with test particle simulations, we investigate the ion motions in obliquely propagating magnetosonic waves and find that the ion motions also become stochastic when the amplitude of the magnetosonic waves is sufficiently large due to the resonance at sub-cyclotron frequencies. Similar to the Alfven wave, the increase of the propagating angle, wave frequency, and the number of the wave modes can lower the stochastic threshold of the ion motions. However, because the magnetosonic waves become more and more compressive with the increase of the propagating angle, the decrease of the stochastic threshold with the increase of the propagating angle is more obvious in the magnetosonic waves than that in the Alfven waves.

  3. Propagation of nonlinear ion acoustic wave with generation of long-wavelength waves

    International Nuclear Information System (INIS)

    Ohsawa, Yukiharu; Kamimura, Tetsuo

    1978-01-01

    The nonlinear propagation of the wave packet of an ion acoustic wave with wavenumber k 0 asymptotically equals k sub(De) (the electron Debye wavenumber) is investigated by computer simulations. From the wave packet of the ion acoustic wave, waves with long wavelengths are observed to be produced within a few periods for the amplitude oscillation of the original wave packet. These waves are generated in the region where the original wave packet exists. Their characteristic wavelength is of the order of the length of the wave packet, and their propagation velocity is almost equal to the ion acoustic speed. The long-wavelength waves thus produced strongly affect the nonlinear evolution of the original wave packet. (auth.)

  4. Rogue and shock waves in nonlinear dispersive media

    CERN Document Server

    Resitori, Stefania; Baronio, Fabio

    2016-01-01

    This self-contained set of lectures addresses a gap in the literature by providing a systematic link between the theoretical foundations of the subject matter and cutting-edge applications in both geophysical fluid dynamics and nonlinear optics. Rogue and shock waves are phenomena that may occur in the propagation of waves in any nonlinear dispersive medium. Accordingly, they have been observed in disparate settings – as ocean waves, in nonlinear optics, in Bose-Einstein condensates, and in plasmas. Rogue and dispersive shock waves are both characterized by the development of extremes: for the former, the wave amplitude becomes unusually large, while for the latter, gradients reach extreme values. Both aspects strongly influence the statistical properties of the wave propagation and are thus considered together here in terms of their underlying theoretical treatment. This book offers a self-contained graduate-level text intended as both an introduction and reference guide for a new generation of scientists ...

  5. Interaction of langmuir and ion acoustic waves

    International Nuclear Information System (INIS)

    Lee, Hee Jae

    1991-01-01

    Interaction of Langmuir and ion acoustic waves in a plasma is described by Landau-Ginzburg type of equation when the group velocity of the Langmuir wave is equal to the wave velocity of ion acoustic wave. (Author)

  6. Ion hole formation and nonlinear generation of electromagnetic ion cyclotron waves: THEMIS observations

    Science.gov (United States)

    Shoji, Masafumi; Miyoshi, Yoshizumi; Katoh, Yuto; Keika, Kunihiro; Angelopoulos, Vassilis; Kasahara, Satoshi; Asamura, Kazushi; Nakamura, Satoko; Omura, Yoshiharu

    2017-09-01

    Electromagnetic plasma waves are thought to be responsible for energy exchange between charged particles in space plasmas. Such an energy exchange process is evidenced by phase space holes identified in the ion distribution function and measurements of the dot product of the plasma wave electric field and the ion velocity. We develop a method to identify ion hole formation, taking into consideration the phase differences between the gyromotion of ions and the electromagnetic ion cyclotron (EMIC) waves. Using this method, we identify ion holes in the distribution function and the resulting nonlinear EMIC wave evolution from Time History of Events and Macroscale Interactions during Substorms (THEMIS) observations. These ion holes are key to wave growth and frequency drift by the ion currents through nonlinear wave-particle interactions, which are identified by a computer simulation in this study.

  7. Parametrics for Molecular Deuterium Concentrations in the Source Region of the UW-IEC Device Using an Ion Acoustic Wave Diagnostic

    Science.gov (United States)

    Boris, D. R.; Emmert, G. A.

    2007-11-01

    The ion source region of the UW-Inertial Electrostatic Confinement device is comprised of a filament assisted DC discharge plasma that exists between the wall of the IEC vacuum chamber and the grounded spherical steel grid that makes up the anode of the IEC device. A 0-dimensional rate equation calculation of the molecular deuterium ion species concentration has been applied utilizing varying primary electron energy, and neutral gas pressure. By propagating ion acoustic waves in the source region of the IEC device the concentrations of molecular deuterium ion species have been determined for these varying plasma conditions, and high D3^+ concentrations have been verified. This was done by utilizing the multi-species ion acoustic wave dispersion relation, which relates the phase speed of the multi-species ion acoustic wave, vph, to the sum in quadrature of the concentration weighted ion acoustic sound speeds of the individual ion species.

  8. Propagation and dispersion of shock waves in magnetoelastic materials

    Science.gov (United States)

    Crum, R. S.; Domann, J. P.; Carman, G. P.; Gupta, V.

    2017-12-01

    Previous studies examining the response of magnetoelastic materials to shock waves have predominantly focused on applications involving pulsed power generation, with limited attention given to the actual wave propagation characteristics. This study provides detailed magnetic and mechanical measurements of magnetoelastic shock wave propagation and dispersion. Laser generated rarefacted shock waves exceeding 3 GPa with rise times of 10 ns were introduced to samples of the magnetoelastic material Galfenol. The resulting mechanical measurements reveal the evolution of the shock into a compressive acoustic front with lateral release waves. Importantly, the wave continues to disperse even after it has decayed into an acoustic wave, due in large part to magnetoelastic coupling. The magnetic data reveal predominantly shear wave mediated magnetoelastic coupling, and were also used to noninvasively measure the wave speed. The external magnetic field controlled a 30% increase in wave propagation speed, attributed to a 70% increase in average stiffness. Finally, magnetic signals propagating along the sample over 20× faster than the mechanical wave were measured, indicating these materials can act as passive antennas that transmit information in response to mechanical stimuli.

  9. Ion rarefaction waves and associated phenomena

    International Nuclear Information System (INIS)

    Coates, A.J.

    1982-01-01

    This thesis contains an experimental and theoretical study of the response of a plasma to the motion of the positive space-charge sheath which bounds it . It is known theoretically that, if a sheath edge is moved at a speed less than the speed of ion acoustic waves, a region of ion rarefaction propagates into the plasma at the ion acoustic speed. Some calculations are described which include the effects of an initial presheath by constructing a one-dimensional plasma solution where a production term balances the losses of ions to the walls. The plasma response to the motion of one boundary is found using the method of characteristics with appropriate boundary conditions. Ion rarefaction waves are associated with expanding sheaths while ion 'enhancement' waves (compressive features) are formed on sheath collapse. In each case the wavefront moves at the local ion acoustic speed which includes the effects of ion drift. The presence of the presheath is essential to the generation of enhancements. The constructional details of a multidipole device are discussed, and the results of Langmuir probe and ion acoustic wave experiments are used to determine the parameters of a quiescent argon plasma. Some experiments on moving sheaths in such a plasma are then considered. (author)

  10. Excitation of short-scale fluctuations by parametric decay of helicon waves into ion-sound and Trivelpiece-Gould waves

    International Nuclear Information System (INIS)

    Lorenz, B; Kraemer, M; Selenin, V L; Aliev, Yu M

    2005-01-01

    The helicon wave field and the excitation of short-scale electrostatic fluctuations in a helicon-produced plasma are closely related as both the helicon wave damping and the fluctuation level are shown to increase with the launched rf power. Correlation methods using electrostatic probes as well as microwave back-scattering at the upper-hybrid resonance are applied to obtain the dispersion relations of the fluctuations in the low-frequency and high-frequency ranges. The frequency and wavenumber spectra measured for all components of the wave vector allow us to identify the fluctuations as ion-sound and Trivelpiece-Gould waves that originate from parametric decay of the helicon pump wave. The growth rates and thresholds inferred from the evolution of the fluctuations in a wide range of helicon plasma parameters are in good agreement with predictions for the parametric decay instability that takes into account realistic damping rates for the decay waves as well as non-vanishing parallel wavenumber of the helicon pump

  11. Long wave dispersion relations for surface waves in a magnetically structured atmosphere

    International Nuclear Information System (INIS)

    Rae, I.C.; Roberts, B.

    1983-01-01

    A means of obtaining approximate dispersion relations for long wavelength magnetoacoustic surface waves propagating in a magnetically structured atmosphere is presented. A general dispersion relation applying to a wide range of magnetic profiles is obtained, and illustrated for the special cases of a single interface and a magnetic slab. In the slab geometry, for example, the dispersion relation contains both the even (sausage) and odd (kink) modes in one formalism

  12. Robust Imaging Methodology for Challenging Environments: Wave Equation Dispersion Inversion of Surface Waves

    KAUST Repository

    Li, Jing; Schuster, Gerard T.; Zeng, Zhaofa

    2017-01-01

    A robust imaging technology is reviewed that provide subsurface information in challenging environments: wave-equation dispersion inversion (WD) of surface waves for the shear velocity model. We demonstrate the benefits and liabilities of the method

  13. Investigations of electrostatic ion waves in a collisionless plasma

    International Nuclear Information System (INIS)

    Michelsen, P.

    1980-06-01

    The author reviews a series of publications concerning theoretical and experimental investigations of electrostatic ion waves in a collisionless plasma. The experimental work was performed in the Risoe Q-machine under various operational conditions. Besides a description of this machine and the diagnostic techniques used for the measurements, two kinds of electrostatic waves are treated, namely, ion-acoustic waves and ion-cyclotron waves. Due to the relative simplicity of the ion-acoustic waves, these were treated in detail in order to get a more general understanding of the behaviour of the propagation properties of electrostatic waves. The problem concerning the difficulties in describing waves excited at a certain position and propagating in space by a proper mathematical model was especially considered in depth. Furthermore, ion-acoustic waves were investigated which propagated in a plasma with a density gradient, and afterwards in a plasma with an ion beam. Finally, a study of the electrostatic ion-cyclotron waves was undertaken, and it was shown that these waves were unstable in a plasma traversed by an ion beam. (Auth.)

  14. The essential theory of fast wave current drive with full wave method

    International Nuclear Information System (INIS)

    Liu Yan; Gong Xueyu; Yang Lei; Yin Chenyan; Yin Lan

    2007-01-01

    The full wave numerical method is developed for analyzing fast wave current drive in the range of ion cyclotron waves in tokamak plasmas, taking into account finite larmor radius effects and parallel dispersion. the physical model, the dispersion relation on the assumption of Finite Larmor Radius (FLR) effects and the form of full wave be used for computer simulation are developed. All of the work will contribute to further study of fast wave current drive. (authors)

  15. Dispersion analysis for waves propagated in fractured media

    Energy Technology Data Exchange (ETDEWEB)

    Lesniak, A; Niitsuma, H [Tohoku University, Sendai (Japan). Faculty of Engineering

    1996-05-01

    Dispersion of velocity is defined as a variation of the phase velocity with frequency. This paper describes the dispersion analysis of compressional body waves propagated in the heterogeneous fractured media. The new method proposed and discussed here permitted the evaluation of the variation in P wave arrival with frequency. For this processing method, any information about the attenuation of the medium are not required, and only an assumption of weak heterogeneity is important. It was shown that different mechanisms of dispersion can be distinguished and its value can be quantitatively estimated. Although the frequency used in this study was lower than those in most previous experiments reported in literature, the evaluated dispersion was large. It was suggested that such a large dispersion may be caused by the velocity structure of the media studied and by frequency dependent processes in a highly fractured zone. It was demonstrated that the present method can be used in the evaluation of subsurface fracture systems or characterization of any kind of heterogeneities. 10 refs., 6 figs.

  16. Ion acoustic waves in the solar wind

    International Nuclear Information System (INIS)

    Gurnett, D.A.; Frank, L.A.

    1978-01-01

    Plasma wave measurements on the Helios I and 2 spacecraft have revealed the occurrence of electric field turbulence in the solar wind at frequencies between the electron and ion plasma frequencies. Wavelength measurements with the Imp 6 spacecraft now provide strong evidence that these waves are short-wavelength ion acoustic waves which are Doppler-shifted upward in frequency by the motion of the solar wind. Comparison of the Helios results with measurements from the earth-orbiting Imp 6 and 8 spacecraft shows that the ion acoustic turbulence detected in interplanetary space has characteristics essentially identical to those of bursts of electrostatic turbulence generated by protons streaming into the solar wind from the earth's bow shock. In a few cases, enhanced ion acoustic wave intensities have been observed in direct association with abrupt increases in the anisotropy of the solar wind electron distribution. This relationship strongly suggests that the ion acoustic waves detected by Helios far from the earth are produced by an electron heat flux instability, as was suggested by Forslund. Possible related mechanisms which could explain the generation of ion acoustic waves by protons streaming into the solar wind from the earth's bow shock are also considered

  17. Inferring Magnetospheric Heavy Ion Density using EMIC Waves

    Energy Technology Data Exchange (ETDEWEB)

    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.

  18. Variational Boussinesq model for strongly nonlinear dispersive waves

    NARCIS (Netherlands)

    Lawrence, C.; Adytia, D.; van Groesen, E.

    2018-01-01

    For wave tank, coastal and oceanic applications, a fully nonlinear Variational Boussinesq model with optimized dispersion is derived and a simple Finite Element implementation is described. Improving a previous weakly nonlinear version, high waves over flat and varying bottom are shown to be

  19. Non-Linear Excitation of Ion Acoustic Waves

    DEFF Research Database (Denmark)

    Michelsen, Poul; Hirsfield, J. L.

    1974-01-01

    The excitation of ion acoustic waves by nonlinear coupling of two transverse magnetic waves generated in a microwave cavity was investigated. Measurements of the wave amplitude showed good agreement with calculations based on the Vlasov equation.......The excitation of ion acoustic waves by nonlinear coupling of two transverse magnetic waves generated in a microwave cavity was investigated. Measurements of the wave amplitude showed good agreement with calculations based on the Vlasov equation....

  20. Fully kinetic simulation of ion acoustic and dust-ion acoustic waves

    International Nuclear Information System (INIS)

    Hosseini Jenab, S. M.; Kourakis, I.; Abbasi, H.

    2011-01-01

    A series of numerical simulations is presented, based on a recurrence-free Vlasov kinetic model using kinetic phase point trajectories. All plasma components are modeled kinetically via a Vlasov evolution equation, then coupled through Poisson's equation. The dynamics of ion acoustic waves in an electron-ion and in a dusty (electron-ion-dust) plasma configuration are investigated, focusing on wave decay due to Landau damping and, in particular, on the parametric dependence of the damping rate on the dust concentration and on the electron-to-ion temperature ratio. In the absence of dust, the occurrence of damping was observed, as expected, and its dependence to the relative magnitude of the electron vs ion temperature(s) was investigated. When present, the dust component influences the charge balance, enabling dust-ion acoustic waves to survive Landau damping even in the extreme regime where T e ≅ T i . The Landau damping rate is shown to be minimized for a strong dust concentration or/and for a high value of the electron-to-ion temperature ratio. Our results confirm earlier theoretical considerations and contribute to the interpretation of experimental observations of dust-ion acoustic wave characteristics.

  1. Study of mode-converted and directly-excited ion Bernstein waves by CO2 laser scattering in Alcator C

    International Nuclear Information System (INIS)

    Takase, Y.; Fiore, C.L.; McDermott, F.S.; Moody, J.D.; Porkolab, M.; Shepard, T.; Squire, J.

    1987-01-01

    Mode-converted and directly excited ion Bernstein waves (IBW) were studied using CO 2 laser scattering in the Alcator C tokamak. During the ICRF fast wave heating experiments, mode-converted IBW was observed on the high-field side of the resonance in both second harmonic and minority heating regimes. By comparing the relative scattered powers from the two antennas separated by 180 0 toroidally, an increased toroidal wave damping with increasing density was inferred. In the IBW heating experiments, optimum direct excitation is obtained when an ion-cyclotron harmonic layer is located just behind the antenna. Wave absorption at the ω = 3Ω/sub D/ = 1.5Ω/sub H/ layer was directly observed. Edge ion heating was inferred from the IBW dispersion when this absorption layer was located in the plasma periphery, which may be responsible for the observed improvement in particle confinement

  2. Novel wave/ion beam interaction approach to isotope separation

    International Nuclear Information System (INIS)

    Post, R.F.; Lowder, R.S.; Schwager, L.A.; Barr, W.L.; Warner, B.E.

    1993-02-01

    Numerical simulations and experimental studies have been made related to the possibility of employing an externally imposed electrostatic potential wave to separate isotopes. This wave/ion interaction is a sensitive function of the wave/ion difference velocity and for the appropriate wave amplitude and wave speed, a lighter faster isotope will be reflected by the wave to a higher energy while leaving heavier, slower isotopes virtually undisturbed in energy -- allowing subsequent ion separation by simple energy discrimination. In these experiments, a set of some 200 individual, electrodes, which surrounded a microamp beam of neon ions, was used to generate the wave. Measurements of the wave amplitudes needed for ion reflection and measurements of the final energies of those reflected ions are consistent with values expected from simple kinetic arguments and with the more detailed results of numeric simulations

  3. Mode conversion of fast Alfvacute en waves at the ion endash ion hybrid resonance

    International Nuclear Information System (INIS)

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

    1996-01-01

    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 endash ion hybrid resonance inside the plasma, then some of the power from the antenna, delivered into the plasma by fast Alfvacute en 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 Alfvacute en waves in the immediate vicinity of the ion endash ion hybrid resonance is extended to include the propagation and reflection of the fast Alfvacute en waves on the high magnetic-field side of the ion endash ion hybrid resonance. It is shown that there exist plasma conditions for which the entire fast Alfvacute en wave power incident on the ion endash ion hybrid resonance can be converted to ion-Bernstein waves. In this extended analysis of the mode conversion process, the fast Alfvacute en waves can be envisioned as being coupled to an internal plasma resonator. This resonator extends from the low magnetic-field cutoff near the ion endash ion hybrid resonance to the high magnetic-field cutoff. The condition for 100% mode conversion corresponds to a critical coupling of the fast Alfvacute en 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. copyright 1996 American Institute of Physics

  4. Effects of heavy ion temperature on low-frequency kinetic Alfven waves

    International Nuclear Information System (INIS)

    Yang, L.; Wu, D. J.

    2011-01-01

    Heavy ion-electron (or proton) temperature ratio varies in a wide range in the solar and space environment. In this paper, proton and heavy ion temperatures are included in a three-fluid plasma model. For the specified parameters, low-frequency (<< heavy ion gyrofrequency) kinetic Alfven waves (KAWs) with sub- and super-Alfvenic speeds are found to coexist in the same plasma environment. Our results show that the temperature ratio of heavy ions to electrons can considerably affect the dispersion, propagation, and electromagnetic polarizations of the KAWs. In particular, the temperature ratio can increase the ratio of parallel to perpendicular electric fields and the normalized electric to magnetic field ratio, the variations of which are greatly different in regions with a high heavy ion temperature and with a low one. The results may help to understand the physical mechanism of some energization processes of heavy ions in the solar and space plasma environment. Effects of the ratio of electron thermal to Alfven speeds and the heavy ion abundance on these parameters are also discussed.

  5. Influence of the interaction of ions-dust grains on ion acoustic wave and dust acoustic wave

    International Nuclear Information System (INIS)

    Hua Jianjun; Liu Jinyuan; Ma Tengcai

    2004-01-01

    Based on a set of hydrodynamic equations and a linear time-dependent perturbation theory, the influence of the interaction of ions-dust grains on ion acoustic wave IAW and dust acoustic wave DAW in dusty plasma is analyzed. The results show that the interaction makes IAW more stable and DAW less stable

  6. A heating mechanism of ions due to large amplitude coherent ion acoustic wave

    International Nuclear Information System (INIS)

    Yajima, Nobuo; Kawai, Yoshinobu; Kogiso, Ken.

    1978-05-01

    Ion heating mechanism in a plasma with a coherent ion acoustic wave is studied experimentally and numerically. Ions are accelerated periodically in the electrostatic potential of the coherent wave and their oscillation energy is converted into the thermal energy of ions through the collision with the neutral atoms in plasma. The Monte Carlo calculation is applied to obtain the ion temperature. The amplitude of the electrostatic potential, the mean number of collisions and the mean life time of ions are treated as parameters in the calculation. The numerical results are compared with the experiments and both of them agree well. It is found that the ion temperature increases as the amplitude of the coherent wave increases and the high energy tail in the distribution function of ions are observed for the case of large wave-amplitude. (author)

  7. The collapse of acoustic waves in dispersive media

    International Nuclear Information System (INIS)

    Kuznetsov, E.A.; Musher, S.L.; Shafarenko, A.V.

    1983-01-01

    The existence of the collapse of acoustic waves with a positive dispersion is demonstrated. A qualitative description of wave collapse, based on the analysis of invariants, is proposed. Through the use of a numerical simulation, it is established that, in the Kadomtsev-Petviashvili three-dimensional equation, collapse is accompanied by the formation of a weakly turbulent background by the wave radiation from the cavity

  8. Electromagnetic waves in optical fibres in a magnetic field

    International Nuclear Information System (INIS)

    Gorelik, V S; Burdanova, M G

    2016-01-01

    A new method is reported of recording the secondary radiation of luminescent substances based on the use of capillary fibres of great length. Theoretical analysis of the dispersion curves of electromagnetic radiation in capillary fibres doped with erbium ions Er 3+ has been established. The Lorentz model is used for describing the dispersion properties of electromagnetic waves in a homogeneous medium doped with rare-earth ions. The dispersion dependencies of polariton and axion–polariton waves in erbium nitrate hydrate are determined on the basis of the model of the interaction between electromagnetic waves and the resonance electronic states of erbium ions in the absence and presence of a magnetic field. (paper)

  9. Increased P-wave dispersion a risk for atrial fibrillation in adolescents with anorexia nervosa.

    Science.gov (United States)

    Ertuğrul, İlker; Akgül, Sinem; Derman, Orhan; Karagöz, Tevfik; Kanbur, Nuray

    2016-01-01

    Studies have shown that a prolonged P-wave dispersion is a risk factor for the development of atrial fibrillation. The aim of this study was to evaluate P-wave dispersion in adolescents with anorexia nervosa at diagnosis. We evaluated electrocardiographic findings, particularly the P-wave dispersion, at initial assessment in 47 adolescents with anorexia nervosa. Comparison of P-wave dispersion between adolescents with anorexia nervosa and controls showed a statistically significant higher P-wave dispersion in patients with anorexia nervosa (72 ± 16.3 msec) when compared to the control group (43.8 ± 9.5 msec). Percent of body weight lost, lower body mass index, and higher weight loss rate in the patients with anorexia nervosa had no effect on P-wave dispersion. Due to the fact that anorexia nervosa has a high mortality rate we believe that cardiac pathologies such as atrial fibrillation must also be considered in the medical evaluation.

  10. Relativistic electromagnetic waves in an electron-ion plasma

    Science.gov (United States)

    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.

  11. A full wave code for ion cyclotron waves in toroidal plasmas

    International Nuclear Information System (INIS)

    Brambilla, M.

    1996-02-01

    The code TORIC solves the finite Larmor radius wave equations in the ion cyclotron frequency range in arbitrary axisymmetric toroidal geometry. The model used describes the compressional and torsional Alfven waves (or, depending on the parallel phase velocity, the kinetic counterpart of the latter), and ion Bernstein waves excited by mode conversion near the first ion cyclotron harmonic. In the ion response the broadening of the absorption regions due to the finite width of the cyclotron resonance of individual ions in toroidal geometry is taken into account. The parallel component of the wave electric field is evaluated on the same footing as the transverse ones; the response of the electrons includes Landau damping, Transit Time damping and the mixed term. The numerical approach uses a spectral representation of the solution in the poloidal angle θ, and cubic finite elements in the radial variable ψ. Great flexibility is provided in the way ion Bernstein waves excited by mode conversion are damped when their wavelength becomes comparable with the ion Larmor radius, in the regularization of Alfven resonances, and in the treatment of the outer plasma layers. As an option, we have also implemented the Order Reduction Algorithm, which provides a particularly fast, yet accurate evaluation of the power deposition profiles in toroidal geometry. Thee present report describes the model and its numerical implementation, and provides the information needed to use the code. A few examples illustrating applications of TORIC are also included. (orig.)

  12. Super rogue wave in plasma

    International Nuclear Information System (INIS)

    Pathak, Pallabi; Sharma, Sumita Kumari; Bailung, Heremba

    2015-01-01

    The evolution of super rogue wave having amplitude ∼5 times the background wave has been observed in multicomponent plasma with critical concentration of negative ions in a double plasma device. In normal electron-ion plasma the ion acoustic solitons are described by the Korteweg-de Vries (KdV) equation. At a critical concentration of negative ions, the ion acoustic modified KdV solitons are found to propagate. Multicomponent plasma also supports the propagation of a special kind of soliton namely 'Peregrine soliton' at critical concentration of negative ions. Peregrine soliton is a doubly localized solution of the nonlinear Schrodinger equation (NLSE) having amplitude 3 times the background carrier wave. In a double plasma device, ion-acoustic Peregrine soliton is excited by applying slowly varying amplitude modulated continuous sinusoidal signal to the source anode and described by the rational solution of NLSE. The ion acoustic wave is modulationally unstable in multicomponent plasma with critical concentration of negative ions and an initial modulated wave perturbation is found to undergo self-modulation to form localized structures by balancing the nonlinearity with the dispersion. In presence of higher order nonlinearity, propagation of a high amplitude (∼5 times of background carrier wave) ion acoustic Peregrine soliton has been observed experimentally. The existence of such types of higher order wave has been reported in other dispersive media. These are considered to be the prototype of super rogue wave in deep water. In this work, experimental results on the evolution of super rogue wave in a double plasma device are presented and compared with the numerical solution of NLSE. (author)

  13. Absorption and dispersion of ultrasonic waves

    CERN Document Server

    Herzfeld, Karl F; Massey, H S W; Brueckner, Keith A

    1959-01-01

    Absorption and Dispersion of Ultrasonic Waves focuses on the influence of ultrasonics on molecular processes in liquids and gases, including hydrodynamics, energy exchange, and chemical reactions. The book first offers information on the Stokes-Navier equations of hydrodynamics, as well as equations of motion, viscosity, formal introduction of volume viscosity, and linearized wave equation for a nonviscous fluid. The manuscript then ponders on energy exchange between internal and external degrees of freedom as relaxation phenomenon; effect of slow energy exchange on sound propagation; differe

  14. Numerical study of the Kadomtsev-Petviashvili equation and dispersive shock waves

    Science.gov (United States)

    Grava, T.; Klein, C.; Pitton, G.

    2018-02-01

    A detailed numerical study of the long time behaviour of dispersive shock waves in solutions to the Kadomtsev-Petviashvili (KP) I equation is presented. It is shown that modulated lump solutions emerge from the dispersive shock waves. For the description of dispersive shock waves, Whitham modulation equations for KP are obtained. It is shown that the modulation equations near the soliton line are hyperbolic for the KPII equation while they are elliptic for the KPI equation leading to a focusing effect and the formation of lumps. Such a behaviour is similar to the appearance of breathers for the focusing nonlinear Schrödinger equation in the semiclassical limit.

  15. The parametric decay of dust ion acoustic waves in non-uniform quantum dusty magnetoplasmas

    International Nuclear Information System (INIS)

    Jamil, M.; Ali, Waris; Shah, H. A.; Shahid, M.; Murtaza, G.; Salimullah, M.

    2011-01-01

    The parametric decay instability of a dust ion acoustic wave into low-frequency electrostatic dust-lower-hybrid and electromagnetic shear Alfven waves has been investigated in detail in an inhomogeneous cold quantum dusty plasma in the presence of external/ambient uniform magnetic field. The quantum magnetohydrodynamic model of plasmas with quantum effect arising through the Bohm potential and Fermi degenerate pressure has been employed in order to find the linear and nonlinear responses of the plasma particles for three-wave nonlinear coupling in a dusty magnetoplasma. A relatively high frequency electrostatic dust ion acoustic wave has been taken as the pump wave. It couples with two other low-frequency internal possible modes of the dusty magnetoplasma, viz., the dust-lower-hybrid and shear Alfven waves. The nonlinear dispersion relation of the dust-lower-hybrid wave has been solved to obtain the growth rate of the parametric decay instability. The growth rate is at a maximum for a small value of the external magnetic field B 0 . It is noted that the growth rate is proportional to the unperturbed electron number density n oe and is independent of inhomogeneity beyond L e =2 cm. An extraordinary growth rate is observed with the quantum effect.

  16. Ion-acoustic cnoidal wave and associated non-linear ion flux in dusty plasma

    Energy Technology Data Exchange (ETDEWEB)

    Jain, S. L. [Poornima Group of Institution, Sitapura, Jaipur 302022 (India); Tiwari, R. S. [Regional College for Education, Research and Technology, Jaipur 302022 (India); Mishra, M. K. [Department of Physics, University of Rajasthan, Jaipur 302004 (India)

    2012-10-15

    Using reductive perturbation method with appropriate boundary conditions, coupled evolution equations for first and second order potentials are derived for ion-acoustic waves in a collisionless, un-magnetized plasma consisting of hot isothermal electrons, cold ions, and massive mobile charged dust grains. The boundary conditions give rise to renormalization term, which enable us to eliminate secular contribution in higher order terms. Determining the non secular solution of these coupled equations, expressions for wave phase velocity and averaged non-linear ion flux associated with ion-acoustic cnoidal wave are obtained. Variation of the wave phase velocity and averaged non-linear ion flux as a function of modulus (k{sup 2}) dependent wave amplitude are numerically examined for different values of dust concentration, charge on dust grains, and mass ratio of dust grains with plasma ions. It is found that for a given amplitude, the presence of positively (negatively) charged dust grains in plasma decreases (increases) the wave phase velocity. This behavior is more pronounced with increase in dust concentrations or increase in charge on dust grains or decrease in mass ratio of dust grains. The averaged non-linear ion flux associated with wave is positive (negative) for negatively (positively) charged dust grains in the plasma and increases (decreases) with modulus (k{sup 2}) dependent wave amplitude. For given amplitude, it increases (decreases) as dust concentration or charge of negatively (positively) charged dust grains increases in the plasma.

  17. High frequency ion sound waves associated with Langmuir waves in type III radio burst source regions

    Directory of Open Access Journals (Sweden)

    G. Thejappa

    2004-01-01

    Full Text Available Short wavelength ion sound waves (2-4kHz are detected in association with the Langmuir waves (~15-30kHz in the source regions of several local type III radio bursts. They are most probably not due to any resonant wave-wave interactions such as the electrostatic decay instability because their wavelengths are much shorter than those of Langmuir waves. The Langmuir waves occur as coherent field structures with peak intensities exceeding the Langmuir collapse thresholds. Their scale sizes are of the order of the wavelength of an ion sound wave. These Langmuir wave field characteristics indicate that the observed short wavelength ion sound waves are most probably generated during the thermalization of the burnt-out cavitons left behind by the Langmuir collapse. Moreover, the peak intensities of the observed short wavelength ion sound waves are comparable to the expected intensities of those ion sound waves radiated by the burnt-out cavitons. However, the speeds of the electron beams derived from the frequency drift of type III radio bursts are too slow to satisfy the needed adiabatic ion approximation. Therefore, some non-linear process such as the induced scattering on thermal ions most probably pumps the beam excited Langmuir waves towards the lower wavenumbers, where the adiabatic ion approximation is justified.

  18. A phase space approach to wave propagation with dispersion.

    Science.gov (United States)

    Ben-Benjamin, Jonathan S; Cohen, Leon; Loughlin, Patrick J

    2015-08-01

    A phase space approximation method for linear dispersive wave propagation with arbitrary initial conditions is developed. The results expand on a previous approximation in terms of the Wigner distribution of a single mode. In contrast to this previously considered single-mode case, the approximation presented here is for the full wave and is obtained by a different approach. This solution requires one to obtain (i) the initial modal functions from the given initial wave, and (ii) the initial cross-Wigner distribution between different modal functions. The full wave is the sum of modal functions. The approximation is obtained for general linear wave equations by transforming the equations to phase space, and then solving in the new domain. It is shown that each modal function of the wave satisfies a Schrödinger-type equation where the equivalent "Hamiltonian" operator is the dispersion relation corresponding to the mode and where the wavenumber is replaced by the wavenumber operator. Application to the beam equation is considered to illustrate the approach.

  19. Dispersion properties of transverse waves in electrically polarized BECs

    International Nuclear Information System (INIS)

    Andreev, Pavel A; Kuz'menkov, L S

    2014-01-01

    Further development of the method of quantum hydrodynamics in applications for Bose–Einstein condensates (BECs) is presented. To consider the evolution of polarization direction along with particle movement, we have developed a corresponding set of quantum hydrodynamic equations. It includes equations of the polarization evolution and the polarization-current evolution along with the continuity equation and the Euler equation (the momentum-balance equation). Dispersion properties of the transverse waves, including the electromagnetic waves propagating through the BECs, are considered. To this end, we consider a full set of the Maxwell equations for the description of electromagnetic field dynamics. This approximation gives us the possibility of considering the electromagnetic waves along with the matter waves. We find a splitting of the electromagnetic-wave dispersion on two branches. As a result, we have four solutions, two for the electromagnetic waves and two for the matter waves; the last two are the concentration-polarization waves appearing as a generalization of the Bogoliubov mode. We also find that if the matter wave propagates perpendicular to the external electric field then the dipolar contribution does not disappear (as it follows from our generalization of the Bogoliubov spectrum). A small dipolar frequency shift exists in this case due to the transverse electric field of perturbation. (paper)

  20. Relation between the behaviors of P-wave and QT dispersions in elderly patients with heart failure

    Directory of Open Access Journals (Sweden)

    Szlejf Cláudia

    2002-01-01

    Full Text Available OBJECTIVE: To assess the relation between P-wave and QT dispersions in elderly patients with heart failure. METHODS: Forty-seven elderly patients (75.6±6 years with stable heart failure in NYHA functional classes II or III and with ejection fractions of 37±6% underwent body surface mapping to analyze P-wave and QT dispersions. The degree of correlation between P-wave and QT dispersions was assessed, and P-wave dispersion values in patients with QT dispersion greater than and smaller than 100 ms were compared. RESULTS: The mean values of P-wave and QT dispersions were 54±14 ms and 68±27 ms, respectively. The correlation between the 2 variables was R=0.41 (p=0.04. In patients with QT dispersion values > 100 ms, P-wave dispersion was significantly greater than in those with QT dispersion values < 100 ms (58±16 vs 53±12 ms, p=0.04 . CONCLUSION: Our results suggest that, in elderly patients with heart failure, a correlation between the values of P-wave and QT dispersions exists. These findings may have etiopathogenic, pathophysiologic, prognostic, and therapeutic implications, which should be investigated in other studies.

  1. Ion-acoustic cnoidal waves in a quantum plasma

    International Nuclear Information System (INIS)

    Mahmood, S.; Haas, F.

    2014-01-01

    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 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

  2. Electrostatic ion cyclotron waves and ion energy diffusion in a mirror machine

    International Nuclear Information System (INIS)

    Turner, W.C.

    1977-01-01

    Measurements of ion cyclotron fluctuations and ion energy diffusion in the neutral beam injected 2XIIB mirror machine are presented. A narrow band single mode spectrum is always observed. When the plasma is de-stabilized by turning off axially injected streaming plasma, the wave amplitude increases and a simultaneous increase in ion-energy diffusion is observed. The spectral properties of the wave do not change. The data are in accord with a wave particle saturation of the drift cyclotron loss cone (DCLC) mode

  3. Experimental study of the propgation and dispersion of internal atmospheric gravity waves

    International Nuclear Information System (INIS)

    Ballard, K.A.

    1981-01-01

    Traveling ionospheric disturbances (TID's) appear as large-scale transverse waves in the F-region (150 to 1000 km altitude), with frequencies on the order of 0.005 to 0.005 cycles per minute, which propagate horizontally over hundreds or even thousands of kilometers. These disturbances have been observed by various radiowave techniques over the past thirty-five years and are now generally accepted as being the manifestation, in the ionized medium, of internal atmospheric gravity waves. A model describing the propagation of gravity waves in an isothermal atmosphere is presented here. The dispersion relation is derived from fundamental principles, and the relation between phase velocity and group velocity is examined. The effects of the Coriolis force and horizontally stratified winds on wave propagation are also analyzed. Conservation of energy in the gravity wave requires increasing amplitude with increasing altitude, inasmuch as the atmospheric density decreases with height. However, this is counteracted by dissipation of wave energy by ion drag, thermal conductivity, and viscous damping. The production of TID's (in the ionized medium) by gravity waves (in the neutral medium) is discussed in quantitative terms, and the vertical predictive function is derived. Dartmouth College has operated a three-station ionosonde network in northern New Hampshire and Vermont on an intermittent basis since 1968. Seven large TID's, found in the 1969 data, are reexamined here in an exhaustive and successful comparison with the gravity wave model. Iso-true-height contours of electron density are used to determine several pertinent TID wave parameters as a function of height

  4. Observations of Two-Stream Ion Wave Instability

    DEFF Research Database (Denmark)

    Christoffersen, G.B.; Prahm, L.P.

    1973-01-01

    A double‐humped ion velocity distribution function is produced in a Q‐machine cesium plasma. When the plasma becomes unstable, a growing wave amplitude and a characteristic change in the phase velocity of a grid‐excited ion‐acoustic wave are observed.......A double‐humped ion velocity distribution function is produced in a Q‐machine cesium plasma. When the plasma becomes unstable, a growing wave amplitude and a characteristic change in the phase velocity of a grid‐excited ion‐acoustic wave are observed....

  5. Quantum X waves with orbital angular momentum in nonlinear dispersive media

    Science.gov (United States)

    Ornigotti, Marco; Conti, Claudio; Szameit, Alexander

    2018-06-01

    We present a complete and consistent quantum theory of generalised X waves with orbital angular momentum in dispersive media. We show that the resulting quantised light pulses are affected by neither dispersion nor diffraction and are therefore resilient against external perturbations. The nonlinear interaction of quantised X waves in quadratic and Kerr nonlinear media is also presented and studied in detail.

  6. Effect of finite ion-temperature on ion-acoustic solitary waves in an inhomogeneous plasma

    International Nuclear Information System (INIS)

    Shivamoggi, B.K.

    1981-01-01

    The propagation of weakly nonlinear ion-acoustic waves in an inhomogeneous plasma is studied taking into account the effect of finite ion temperature. It is found that, whereas both the amplitude and the velocity of propagation decrease as the ion-acoustic solitary wave propagates into regions of higher density, the effect of a finite ion temperature is to reduce the amplitude but enhance the velocity of propagation of the solitary wave. (author)

  7. Effects of Single Dose Energy Drink on QT and P-Wave Dispersion

    Directory of Open Access Journals (Sweden)

    Huseyin Arinc

    2013-12-01

    Full Text Available INTRODUCTION: Aim of this study is to evaluate the cardiac electrophysiological effects of energy drink (Red Bull on QT and P duration and dispersion on surface electrocardiogram. METHODS: Twenty healthy volunteers older than 17 years of age were included the study. Subjects with a cardiac rhythm except sinus rhythm, history of atrial or ventricular arrhythmia, family history of premature sudden cardiac death, palpitations, T-wave abnormalities, QTc interval greater than 440 milliseconds, or those P-waves and QT intervals unavailable in at least eight ECG leads were excluded. Subjects having insomnia, lactose intolerance, caffeine allergy, recurrent headaches, depression, any psychiatric condition, and history of alcohol or drug abuse, pregnant or lactating women were also excluded from participation. 12 lead ECG was obtained before and after consumption of 250 cc enegry drink. QT and P-wave dispersion was calculated. RESULTS: No significant difference have occurred in heart rate (79 ± 14 vs.81 ±13, p=0.68, systolic pressure (114 ± 14 vs.118 ± 16,p=0.38, diastolic blood pressure (74 ± 12 vs.76 ± 14, p=0.64, QT dispersion (58 ± 12 vs. 57 ± 22, p= 0.785 and P-wave dispersion (37 ± 7 vs. 36 ± 13, p= 0.755 between before and 2 hours after consumption of energy drink. DISCUSSION AND CONCLUSION: Consumption of single dose energy drink doesn't affect QT dispersion and P-wave dispersion, heart rate and blood pressure in healthy adults.

  8. Dispersion relation of electromagnetic waves in one-dimensional plasma photonic crystals

    International Nuclear Information System (INIS)

    Hojo, Hitoshi; Mase, Atsushi

    2004-01-01

    The dispersion relation of electromagnetic waves in one-dimensional plasma photonic crystals is studied. The plasma photonic crystal is a periodic array composed of alternating thin plasma and dielectric material. The dispersion relation is obtained by solving a Maxwell wave equation using a method analogous to Kronig-Penny's problem in quantum mechanics, and it is found that the frequency gap and cut-off appear in the dispersion relation. The frequency gap is shown to become larger with the increase of the plasma density as well as plasma width. (author)

  9. Pseudospectral modeling and dispersion analysis of Rayleigh waves in viscoelastic media

    Science.gov (United States)

    Zhang, K.; Luo, Y.; Xia, J.; Chen, C.

    2011-01-01

    Multichannel Analysis of Surface Waves (MASW) is one of the most widely used techniques in environmental and engineering geophysics to determine shear-wave velocities and dynamic properties, which is based on the elastic layered system theory. Wave propagation in the Earth, however, has been recognized as viscoelastic and the propagation of Rayleigh waves presents substantial differences in viscoelastic media as compared with elastic media. Therefore, it is necessary to carry out numerical simulation and dispersion analysis of Rayleigh waves in viscoelastic media to better understand Rayleigh-wave behaviors in the real world. We apply a pseudospectral method to the calculation of the spatial derivatives using a Chebyshev difference operator in the vertical direction and a Fourier difference operator in the horizontal direction based on the velocity-stress elastodynamic equations and relations of linear viscoelastic solids. This approach stretches the spatial discrete grid to have a minimum grid size near the free surface so that high accuracy and resolution are achieved at the free surface, which allows an effective incorporation of the free surface boundary conditions since the Chebyshev method is nonperiodic. We first use an elastic homogeneous half-space model to demonstrate the accuracy of the pseudospectral method comparing with the analytical solution, and verify the correctness of the numerical modeling results for a viscoelastic half-space comparing the phase velocities of Rayleigh wave between the theoretical values and the dispersive image generated by high-resolution linear Radon transform. We then simulate three types of two-layer models to analyze dispersive-energy characteristics for near-surface applications. Results demonstrate that the phase velocity of Rayleigh waves in viscoelastic media is relatively higher than in elastic media and the fundamental mode increases by 10-16% when the frequency is above 10. Hz due to the velocity dispersion of P

  10. Ion-acoustic shock waves with negative ions in presence of dust particulates

    International Nuclear Information System (INIS)

    Sarma, Arun; Nakamura, Y.

    2009-01-01

    Dust acoustics shock waves have been investigated experimentally in a homogeneous unmagnetized dusty plasma device containing negative ions. When the negative ion density larger than a critical concentration 'r c ' negative shock waves were observed instead of positive shock waves. Again when it is nearly equal to 'r c ' both positive and negative shock waves propagate. The experimental findings are compared with modified KdV-Burgers equation. The velocity of the shock waves are also measured and compared with the numerical integration of modified KdV-Burgers equation.

  11. Dispersive waves induced by self-defocusing temporal solitons in a beta-barium-borate crystal

    DEFF Research Database (Denmark)

    Zhou, Binbin; Bache, Morten

    2015-01-01

    We experimentally observe dispersive waves in the anomalous dispersion regime of a beta-barium-borate (BBO) crystal, induced by a self-defocusing few-cycle temporal soliton. Together the soliton and dispersive waves form an energetic octave-spanning supercontinuum. The soliton was excited...

  12. Dispersion relation of linearly polarized strong electromagnetic waves

    Energy Technology Data Exchange (ETDEWEB)

    Ferrari, A; Massaglia, S [Consiglio Nazionale delle Ricerche, Turin (Italy). Lab. di Cosmo-Geofisica; Dobrowolny, M [Comitato Nazionale per l' Energia Nucleaire, Frascati (Italy). Lab. Plasma Spazio

    1975-12-15

    A numerical study is presented of the dispersion relation of linearly polarized strong electromagnetic waves in a cold electron plasma. The nonlinear effects introduced by the relativistic motion of electrons are: (1) the dispersion relation depends explicitly on the field strength ..cap alpha..=eE/sub 0//mc..omega../sub 0/, and (2) the propagation of modes with frequencies below the formal electron plasma frequency is allowed.

  13. Stability analysis of Hasegawa space-charge waves in a plasma waveguide with collisional ion beam

    Science.gov (United States)

    Lee, Myoung-Jae; Jung, Young-Dae

    2017-12-01

    The dispersion relation for the Hasegawa space-charge wave propagating in a cylindrical waveguide dusty plasma containing collision-dominated ion stream is derived by using the fluid equations and the Poisson equation which lead to a Bessel equation. The solution of Bessel equation is null at the boundary and then the roots of the Bessel function would characterize the property of space-charge wave propagation. We have found that the Hasegawa space-charge wave can be excited for a large axial wave number. The growth rate of excitation increases as the order of the roots of the Bessel function increases. The growth rate decreases with an increase of the radius of cylindrical waveguide as well as with an increase of the collision frequency. We found that the disturbance of wave can be damped only for small wave numbers.

  14. Evolution of Modulated Dispersive Electron Waves in a Plasma

    DEFF Research Database (Denmark)

    Sugai, H.; Lynov, Jens-Peter; Michelsen, Poul

    1979-01-01

    The linear propagation of amplitude-modulated electron waves was examined in a low-density Q-machine plasma. Three effects of the strong dispersion on the modulated wave have been demonstrated: (i) a wavepacket expands along its direction of propagation, followed by a shift of the frequency through...

  15. Nonlinear ion-acoustic waves and solitons in a magnetized plasma

    International Nuclear Information System (INIS)

    Lee, L.C.; Kan, J.R.

    1981-01-01

    A unified formulation is presented to study the nonlinear low-frequency electrostatic waves in a magnetized low-β plasma. It is found that there exist three types of nonlinear waves; (1) nonlinear ion-cyclotron periodic waves with a wave speed V/sub p/ > C/sub s/ (ion-acoustic velocity); (2) nonlinear ion-acoustic periodic waves with V/sub p/ < C/sub s/ costheta; and (3) ion-acoustic solitons with C/sub s/ costheta < V/sub p/ < C/sub s/, where theta is the angle between the wave vector and the magnetic field

  16. Dispersion of axially symmetric waves in fluid-filled cylindrical shells

    DEFF Research Database (Denmark)

    Bao, X.L.; Überall, H.; Raju, P. K.

    2000-01-01

    Acoustic waves normally incident on an elastic cylindrical shell can cause the excitation of circumferential elastic waves on the shell. These shells may be empty and fluid immersed, or fluid filled in an ambient medium of air, or doubly fluid loaded inside and out. Circumferential waves...... on such shells have been investigated for the case of aluminum shells, and their phase-velocity dispersion curves have been obtained for double fluid loading [Bao, Raju, and Überall, J. Acoust. Soc. Am. 105, 2704 (1999)]. Similar results were obtained for empty or fluid-filled brass shells [Kumar, Acustica 27......, 317 (1972)]. We have extended the work of Kumar to the case of fluid-filled aluminum shells and steel shells imbedded in air. These cases demonstrate the existence of circumferential waves traveling in the filler fluid, exhibiting a certain simplicity of the dispersion curves of these waves...

  17. Drift wave in pair-ion plasma

    Indian Academy of Sciences (India)

    ion plasma are discussed. It is shown that the temperature and/or mass difference of both species could produce drift wave in a pair-ion plasma. The results are discussed in the context of the fullerene pair-ion plasma experiment.

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

    International Nuclear Information System (INIS)

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

    1984-01-01

    An expression for the linear electromagnetic ion cyclotron convective growth rate has been derived, considering multiple ions in the energetic anisotropic component of the plasma (which provides the free energy for the instability) as well as in the cold component of the plasma. This represents a modification of recent treatments investigating electromagnetic ion cyclotron growth rates which have considered only hydrogen ions in the energetic component. Four major effects on the growth and propagation characteristics result from inclusion of heavy ions in the energetic component. Some wave growth occurs at low frequencies below the corresponding marginally unstable wave mode for each heavy ion. Enhanced quasi-monochronomatic peaks in the convective growth rate appear just below the O + and He + gyrofrequency and can be quite pronounced for certain plasma conditions. Stop bands, decreased group velocity and other effects normally attributed to cold heavy ions can be produced or enhanced by heavy ions in the energetic plasma component. Partial or complete suppression of wave growth at frequencies above the marginally unstable wave mode for a particular energetic heavy ion can greatly alter the growth rates that would occur in the absence of this energetic heavy ion. The expression for the linear electromagnetic ion cyclotron convective growth rate along with appropriate plasma parameters was used to investigate the nature of linear wave growth in the plasmapause region. The frequencies of peaks in the convective growth rate given by this model compare favorably with wave measurements in this region. It is conceivable that through wave-particle interactions, electromagnetic ion cyclotron waves could supply the energy source for various plasmapause region phenomena such as the O + torus, the plasma cloak and stable auroral red arcs

  19. Effects of metal and 'magnetic wall' on the dispersion characteristic of magnetostatic waves

    International Nuclear Information System (INIS)

    Lock, Edwin H.; Vashkovsky, Anatoly V.

    2006-01-01

    The dispersion relation of magnetostatic waves tangentially magnetized to saturation ferrite film, with a 'magnetic wall' condition (tangential component of microwave magnetic field is equal to zero) on one of the film surface and with a metal condition on the opposite surface is analyzed. The dispersion characteristics show that unidirectional magnetostatic waves appear in this structure: they can transfer energy in one direction only and fundamentally cannot transfer energy in the opposite direction. The dispersion-free propagation of magnetostatic waves also is possible in the structure in a wide frequency interval

  20. Acoustic nonlinear periodic waves in pair-ion plasmas

    Science.gov (United States)

    Mahmood, Shahzad; Kaladze, Tamaz; Ur-Rehman, Hafeez

    2013-09-01

    Electrostatic acoustic nonlinear periodic (cnoidal) waves and solitons are investigated in unmagnetized pair-ion plasmas consisting of same mass and oppositely charged ion species with different temperatures. Using reductive perturbation method and appropriate boundary conditions, the Korteweg-de Vries (KdV) equation is derived. The analytical solutions of both cnoidal wave and soliton solutions are discussed in detail. The phase plane plots of cnoidal and soliton structures are shown. It is found that both compressive and rarefactive cnoidal wave and soliton structures are formed depending on the temperature ratio of positive and negative ions in pair-ion plasmas. In the special case, it is revealed that the amplitude of soliton may become larger than it is allowed by the nonlinear stationary wave theory which is equal to the quantum tunneling by particle through a potential barrier effect. The serious flaws in the earlier published results by Yadav et al., [PRE 52, 3045 (1995)] and Chawla and Misra [Phys. Plasmas 17, 102315 (2010)] of studying ion acoustic nonlinear periodic waves are also pointed out.

  1. Dispersion and energy conservation relations of surface waves in semi-infinite plasma

    International Nuclear Information System (INIS)

    Atanassov, V.

    1981-01-01

    The hydrodynamic theory of surface wave propagation in semi-infinite homogeneous isotropic plasma is considered. Explicit linear surface wave solutions are given for the electric and magnetic fields, charge and current densities. These solutions are used to obtain the well-known dispersion relations and, together with the general energy conservation equation, to find appropriate definitions for the energy and the energy flow densities of surface waves. These densities are associated with the dispersion relation and the group velocity by formulae similar to those for bulk waves in infinite plasmas. Both cases of high-frequency (HF) and low-frequency (LF) surface waves are considered. (author)

  2. Sparse and Dispersion-Based Matching Pursuit for Minimizing the Dispersion Effect Occurring when Using Guided Wave for Pipe Inspection.

    Science.gov (United States)

    Rostami, Javad; Tse, Peter W T; Fang, Zhou

    2017-06-06

    Ultrasonic guided wave is an effective tool for structural health monitoring of structures for detecting defects. In practice, guided wave signals are dispersive and contain multiple modes and noise. In the presence of overlapped wave-packets/modes and noise together with dispersion, extracting meaningful information from these signals is a challenging task. Handling such challenge requires an advanced signal processing tool. The aim of this study is to develop an effective and robust signal processing tool to deal with the complexity of guided wave signals for non-destructive testing (NDT) purpose. To achieve this goal, Sparse Representation with Dispersion Based Matching Pursuit (SDMP) is proposed. Addressing the three abovementioned facts that complicate signal interpretation, SDMP separates overlapped modes and demonstrates good performance against noise with maximum sparsity. With the dispersion taken into account, an overc-omplete and redundant dictionary of basic atoms based on a narrowband excitation signal is designed. As Finite Element Method (FEM) was used to predict the form of wave packets propagating along structures, these atoms have the maximum resemblance with real guided wave signals. SDMP operates in two stages. In the first stage, similar to Matching Pursuit (MP), the approximation improves by adding, a single atom to the solution set at each iteration. However, atom selection criterion of SDMP utilizes the time localization of guided wave reflections that makes a portion of overlapped wave-packets to be composed mainly of a single echo. In the second stage of the algorithm, the selected atoms that have frequency inconsistency with the excitation signal are discarded. This increases the sparsity of the final representation. Meanwhile, leading to accurate approximation, as discarded atoms are not representing guided wave reflections, it simplifies extracting physical meanings for defect detection purpose. To verify the effectiveness of SDMP for

  3. Sparse and Dispersion-Based Matching Pursuit for Minimizing the Dispersion Effect Occurring when Using Guided Wave for Pipe Inspection

    Directory of Open Access Journals (Sweden)

    Javad Rostami

    2017-06-01

    Full Text Available Ultrasonic guided wave is an effective tool for structural health monitoring of structures for detecting defects. In practice, guided wave signals are dispersive and contain multiple modes and noise. In the presence of overlapped wave-packets/modes and noise together with dispersion, extracting meaningful information from these signals is a challenging task. Handling such challenge requires an advanced signal processing tool. The aim of this study is to develop an effective and robust signal processing tool to deal with the complexity of guided wave signals for non-destructive testing (NDT purpose. To achieve this goal, Sparse Representation with Dispersion Based Matching Pursuit (SDMP is proposed. Addressing the three abovementioned facts that complicate signal interpretation, SDMP separates overlapped modes and demonstrates good performance against noise with maximum sparsity. With the dispersion taken into account, an overc-omplete and redundant dictionary of basic atoms based on a narrowband excitation signal is designed. As Finite Element Method (FEM was used to predict the form of wave packets propagating along structures, these atoms have the maximum resemblance with real guided wave signals. SDMP operates in two stages. In the first stage, similar to Matching Pursuit (MP, the approximation improves by adding, a single atom to the solution set at each iteration. However, atom selection criterion of SDMP utilizes the time localization of guided wave reflections that makes a portion of overlapped wave-packets to be composed mainly of a single echo. In the second stage of the algorithm, the selected atoms that have frequency inconsistency with the excitation signal are discarded. This increases the sparsity of the final representation. Meanwhile, leading to accurate approximation, as discarded atoms are not representing guided wave reflections, it simplifies extracting physical meanings for defect detection purpose. To verify the

  4. 1-D profiling using highly dispersive guided waves

    Science.gov (United States)

    Volker, Arno; van Zon, Tim

    2014-02-01

    Corrosion is one of the industries major issues regarding the integrity of assets. Currently, inspections are conducted at regular intervals to ensure a sufficient integrity level of these assets. Cost reduction while maintaining a high level of reliability and safety of installations is a major challenge. There are many situations where the actual defect location is not accessible, e.g., a pipe support or a partially buried pipe. Guided wave tomography has been developed to reconstruct the wall thickness of steel pipes. In case of bottom of the line corrosion, i.e., a single corrosion pit, a simpler approach may be followed. Data is collected in a pitch-catch configuration at the 12 o'clock position using highly dispersive guided waves. After dispersion correction the data collapses to a short pulse, any residual dispersion indicates wall loss. The phase spectrum is used to invert for the wall thickness profile in the circumferential direction, assuming a Gaussian defect profile. The approach is evaluated on numerically simulated and on measured data. The method is intended for rapid, semi-quantitative screening of pipes.

  5. 1-D profiling using highly dispersive guided waves

    International Nuclear Information System (INIS)

    Volker, Arno; Zon, Tim van

    2014-01-01

    Corrosion is one of the industries major issues regarding the integrity of assets. Currently, inspections are conducted at regular intervals to ensure a sufficient integrity level of these assets. Cost reduction while maintaining a high level of reliability and safety of installations is a major challenge. There are many situations where the actual defect location is not accessible, e.g., a pipe support or a partially buried pipe. Guided wave tomography has been developed to reconstruct the wall thickness of steel pipes. In case of bottom of the line corrosion, i.e., a single corrosion pit, a simpler approach may be followed. Data is collected in a pitch-catch configuration at the 12 o'clock position using highly dispersive guided waves. After dispersion correction the data collapses to a short pulse, any residual dispersion indicates wall loss. The phase spectrum is used to invert for the wall thickness profile in the circumferential direction, assuming a Gaussian defect profile. The approach is evaluated on numerically simulated and on measured data. The method is intended for rapid, semi-quantitative screening of pipes

  6. Study of Ion Acoustic Wave Damping through Green's Functions

    DEFF Research Database (Denmark)

    Hsuan, H.C.S.; Jensen, Vagn Orla

    1973-01-01

    Green's function analyses of ion acoustic waves in streaming plasmas show that, in general, the waves damp algebraically rather than exponentially with distance from exciter.......Green's function analyses of ion acoustic waves in streaming plasmas show that, in general, the waves damp algebraically rather than exponentially with distance from exciter....

  7. Harmonic effects on ion-bulk waves and simulation of stimulated ion-bulk-wave scattering in CH plasmas

    Science.gov (United States)

    Feng, Q. S.; Zheng, C. Y.; Liu, Z. J.; Cao, L. H.; Xiao, C. Z.; Wang, Q.; Zhang, H. C.; He, X. T.

    2017-08-01

    Ion-bulk (IBk) wave, a novel branch with a phase velocity close to the ion’s thermal velocity, discovered by Valentini et al (2011 Plasma Phys. Control. Fusion 53 105017), is recently considered as an important electrostatic activity in solar wind, and thus of great interest to space physics and also inertial confinement fusion. The harmonic effects on IBk waves has been researched by Vlasov simulation for the first time. The condition of excitation of the large-amplitude IBk waves is given. The nature of nonlinear IBk waves in the condition of kFeng scattering (SFS) has been proposed and also verified by Vlasov-Maxwell code. In CH plasmas, in addition to the stimulated Brillouin scattering from multi ion-acoustic waves, there exists SIBS simultaneously. This research gives an insight into the SIBS in the field of laser plasma interaction.

  8. Theory of longitudinal plasma waves with allowance for ion mobility

    International Nuclear Information System (INIS)

    Kichigin, G.N.

    2003-01-01

    One studies propagation of stationary longitudinal plasma wave of high amplitude in collisionless cold plasma with regard to motion of electrons and ions in a wave. One derived dependences of amplitudes of electric field, potential, frequency and length of wave on the speed of wave propagation and on the parameter equal to the ration of ion mass to electron mass. Account of motion of ions in the wave with maximum possible amplitude resulted in nonmonotone dependence of frequency on wave speed [ru

  9. Nonlinear Dispersive Elastic Waves in Solids: Exact, Approximate, and Numerical Solutions

    Science.gov (United States)

    Khajehtourian, Romik

    Wave motion lies at the heart of many disciplines in the physical sciences and engineering. For example, problems and applications involving light, sound, heat, or fluid flow are all likely to involve wave dynamics at some level. A particular class of problems is concerned with the propagation of elastic waves in a solid medium, such as a fiber-reinforced composite material responding to vibratory excitations, or soil and rock admitting seismic waves moments after the onset of an earthquake, or phonon transport in a semiconducting crystal like silicon. Regardless of the type of wave, the dispersion relation provides a fundamental characterization of the elastodynamic properties of the medium. The first part of the dissertation examines the propagation of a large-amplitude elastic wave in a one-dimensional homogeneous medium with a focus on the effects of inherent nonlinearities on the dispersion relation. Considering a thin rod, where the thickness is small compared to the wavelength, an exact, closed-form formulation is presented for the treatment of two types of nonlinearity in the strain-displacement gradient relation: Green-Lagrange and Hencky. The derived relation is then verified by direct time-domain simulations, examining both instantaneous dispersion (by direct observation) and short-term, pre-breaking dispersion (by Fourier transformation). A high-order perturbation analysis is also conducted yielding an explicit analytical space-time solution, which is shown to be spectrally accurate. The results establish a perfect match between theory and simulation and reveal that regardless of the strength of the nonlinearity, the dispersion relation fully embodies all information pertaining to the nonlinear harmonic generation mechanism that unfolds as an arbitrary-profiled wave evolves in the medium. In the second part of the dissertation, the analysis is extended to a continuous periodic thin rod exhibiting multiple phases or embedded local resonators. The

  10. Whimsicality of multi-mode Hasegawa space-charge waves in a complex plasma containing collision-dominated electrons and streaming ions

    Science.gov (United States)

    Lee, Myoung-Jae; Jung, Young-Dae

    2017-09-01

    The influence of collision-dominated electrons on multi-mode Hasegawa space-charge waves are investigated in a complex plasma containing streaming ions. The dispersion relation for the multi-mode Hasegawa space-charge wave propagating in a cylindrical waveguide filled with dusty plasma containing collision-dominated electrons and streaming ions is derived by using the fluid equations and Poisson’s equation which lead to a Bessel equation. By the boundary condition, the roots of the Bessel function would characterize the property of space-charge wave propagation. It is found that two solutions exist for wave frequency, which are affected by the radius of waveguide and the roots of the Bessel function. The damping and growing modes are found to be enhanced by an increase of the radius. However, an increase of electron collision frequency would suppress the damping and the growing modes of the propagating space-charge wave in a cylindrical waveguide plasma.

  11. Contribution of Higher-Order Dispersion to Nonlinear Electron-Acoustic Solitary Waves in a Relativistic Electron Beam Plasma System

    International Nuclear Information System (INIS)

    Zahran, M.A.; El-Shewy, E.K.

    2008-01-01

    The nonlinear properties of solitary wave structures are reported in an unmagnetized collisionless plasma comprising of cold relativistic electron fluid, Maxwellian hot electrons, relativistic electron beam, and stationary ions. The Korteweg--de Vries (KdV) equation has been derived using a reductive perturbation theory. As the wave amplitude increases, the width and velocity of the soliton deviate from the prediction of the KdV equation i.e. the breakdown of the KdV approximation. On the other hand, to overcome this weakness we extend our analysis to obtain the KdV equation with fifth-order dispersion term. The solution of the resulting equation has been obtained

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

    International Nuclear Information System (INIS)

    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

  13. Observation of spin-wave dispersion in Nd-Fe-B magnets using neutron Brillouin scattering

    International Nuclear Information System (INIS)

    Ono, K.; Inami, N.; Saito, K.; Takeichi, Y.; Kawana, D.; Yokoo, T.; Itoh, S.; Yano, M.; Shoji, T.; Manabe, A.; Kato, A.; Kaneko, Y.

    2014-01-01

    The low-energy spin-wave dispersion in polycrystalline Nd-Fe-B magnets was observed using neutron Brillouin scattering (NBS). Low-energy spin-wave excitations for the lowest acoustic spin-wave mode were clearly observed. From the spin-wave dispersion, we were able to determine the spin-wave stiffness constant D sw (100.0 ± 4.9 meV.Å 2 ) and the exchange stiffness constant A (6.6 ± 0.3 pJ/m)

  14. [P wave dispersion increased in childhood depending on blood pressure, weight, height, and cardiac structure and function].

    Science.gov (United States)

    Chávez-González, Elibet; González-Rodríguez, Emilio; Llanes-Camacho, María Del Carmen; Garí-Llanes, Merlin; García-Nóbrega, Yosvany; García-Sáez, Julieta

    2014-01-01

    Increased P wave dispersion are identified as a predictor of atrial fibrillation. There are associations between hypertension, P wave dispersion, constitutional and echocardiographic variables. These relationships have been scarcely studied in pediatrics. The aim of this study was to determine the relationship between P wave dispersion, blood pressure, echocardiographic and constitutional variables, and determine the most influential variables on P wave dispersion increases in pediatrics. In the frame of the PROCDEC II project, children from 8 to 11 years old, without known heart conditions were studied. Arterial blood pressure was measured in all the children; a 12-lead surface electrocardiogram and an echocardiogram were done as well. Left ventricular mass index mean values for normotensive (25.91±5.96g/m(2.7)) and hypertensive (30.34±8.48g/m(2.7)) showed significant differences P=.000. When we add prehypertensive and hypertensive there are 50.38% with normal left ventricular mass index and P wave dispersion was increased versus 13.36% of normotensive. Multiple regression demonstrated that the mean blood pressure, duration of A wave of mitral inflow, weight and height have a value of r=0.88 as related to P wave dispersion. P wave dispersion is increased in pre- and hypertensive children compared to normotensive. There are pre- and hypertensive patients with normal left ventricular mass index and increased P wave dispersion. Mean arterial pressure, duration of the A wave of mitral inflow, weight and height are the variables with the highest influence on increased P wave dispersion. Copyright © 2013 Instituto Nacional de Cardiología Ignacio Chávez. Published by Masson Doyma México S.A. All rights reserved.

  15. Dynamic behavior of ion acoustic waves in electron-positron-ion magnetoplasmas with superthermal electrons and positrons

    Science.gov (United States)

    Saha, Asit; Pal, Nikhil; Chatterjee, Prasanta

    2014-10-01

    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.

  16. Dynamic behavior of ion acoustic waves in electron-positron-ion magnetoplasmas with superthermal electrons and positrons

    Energy Technology Data Exchange (ETDEWEB)

    Saha, Asit, E-mail: asit-saha123@rediffmail.com, E-mail: prasantachatterjee1@rediffmail.com [Department of Mathematics, Sikkim Manipal Institute of Technology, Majitar, Rangpo, East-Sikkim 737136 (India); Department of Mathematics, Siksha Bhavana, Visva Bharati University, Santiniketan-731235 (India); Pal, Nikhil; Chatterjee, Prasanta, E-mail: asit-saha123@rediffmail.com, E-mail: prasantachatterjee1@rediffmail.com [Department of Mathematics, Siksha Bhavana, Visva Bharati University, Santiniketan-731235 (India)

    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.

  17. Nonlinear wave particle interaction in the Earth's foreshock

    Science.gov (United States)

    Mazelle, C.; LeQueau, D.; Meziane, K.; Lin, R. P.; Parks, G.; Reme, H.; Sanderson, T.; Lepping, R. P.

    1997-01-01

    The possibility that ion beams could provide a free energy source for driving an ion/ion instability responsible for the ULF wave occurrence is investigated. For this, the wave dispersion relation with the observed parameters is solved. Secondly, it is shown that the ring-like distributions could then be produced by a coherent nonlinear wave-particle interaction. It tends to trap the ions into narrow cells in velocity space centered around a well-defined pitch-angle, directly related to the saturation wave amplitude in the analytical theory. The theoretical predictions with the observations are compared.

  18. Dispersion formulae for waves in a magneto-active relativistic plasma

    International Nuclear Information System (INIS)

    Misra, P.; Mohanty, J.N.

    1980-01-01

    Dispersion formulae are derived for the transverse waves propagating through a collisionless magneto-active plasma in the direction of the magnetic field valid for relativistic as well as non-relativistic temperatures. Wave propagation under various limiting conditions of temperatures and magnetic field are discussed. (author)

  19. Dispersion formulae for waves in a magneto-active relativistic plasma

    Energy Technology Data Exchange (ETDEWEB)

    Misra, P. (Ravenshaw Coll., Cuttack (India)); Mohanty, J.N. (F.M. College, Balasore (India). Dept. of Physics)

    1980-12-01

    Dispersion formulae are derived for the transverse waves propagating through a collisionless magneto-active plasma in the direction of the magnetic field valid for relativistic as well as non-relativistic temperatures. Wave propagation under various limiting conditions of temperatures and magnetic field are discussed.

  20. Nonlinear ion-acoustic cnoidal waves in a dense relativistic degenerate magnetoplasma.

    Science.gov (United States)

    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.

  1. On Collisionless Damping of Ion Acoustic Waves

    DEFF Research Database (Denmark)

    Jensen, Vagn Orla; Petersen, P.I.

    1973-01-01

    Exact theoretical treatments show that the damping of ion acoustic waves in collisionless plasmas does not vanish when the derivative of the undisturbed distribution function at the phase velocity equals zero.......Exact theoretical treatments show that the damping of ion acoustic waves in collisionless plasmas does not vanish when the derivative of the undisturbed distribution function at the phase velocity equals zero....

  2. Traveling-wave ion mobility mass spectrometry of protein complexes

    DEFF Research Database (Denmark)

    Salbo, Rune; Bush, Matthew F; Naver, Helle

    2012-01-01

    The collision cross-section (Ω) of a protein or protein complex ion can be measured using traveling-wave (T-wave) ion mobility (IM) mass spectrometry (MS) via calibration with compounds of known Ω. The T-wave Ω-values depend strongly on instrument parameters and calibrant selection. Optimization ...

  3. Modal analysis of wave propagation in dispersive media

    Science.gov (United States)

    Abdelrahman, M. Ismail; Gralak, B.

    2018-01-01

    Surveys on wave propagation in dispersive media have been limited since the pioneering work of Sommerfeld [Ann. Phys. 349, 177 (1914), 10.1002/andp.19143491002] by the presence of branches in the integral expression of the wave function. In this article a method is proposed to eliminate these critical branches and hence to establish a modal expansion of the time-dependent wave function. The different components of the transient waves are physically interpreted as the contributions of distinct sets of modes and characterized accordingly. Then, the modal expansion is used to derive a modified analytical expression of the Sommerfeld precursor improving significantly the description of the amplitude and the oscillating period up to the arrival of the Brillouin precursor. The proposed method and results apply to all waves governed by the Helmholtz equations.

  4. Wave dispersion relation of two-dimensional plasma crystals in a magnetic field

    International Nuclear Information System (INIS)

    Uchida, G.; Konopka, U.; Morfill, G.

    2004-01-01

    The wave dispersion relation in a two-dimensional strongly coupled plasma crystal is studied by theoretical analysis and molecular dynamics simulation taking into account a constant magnetic field parallel to the crystal normal. The expression for the wave dispersion relation clearly shows that high-frequency and low-frequency branches exist as a result of the coupling of longitudinal and transverse modes due to the Lorenz force acting on the dust particles. The high-frequency and the low-frequency branches are found to belong to right-hand and left-hand polarized waves, respectively

  5. Controllable behaviours of rogue wave triplets in the nonautonomous nonlinear and dispersive system

    International Nuclear Information System (INIS)

    Dai Chaoqing; Tian Qing; Zhu Shiqun

    2012-01-01

    A similarity transformation connecting the variable coefficient nonlinear Schrödinger equation with the standard nonlinear Schrödinger equation is constructed. The self-similar rogue wave triplet solutions (rational solutions) are analytically obtained for the nonautonomous nonlinear and dispersive system. The controllable behaviours of rogue wave triplets in two typical soliton management systems are discussed. In the exponential dispersion decreasing fibre, three kinds of rogue wave triplets with controllable behaviours are analysed. In the periodic distributed system, the rogue wave triplets recur periodically in the form of a cluster. (paper)

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

    International Nuclear Information System (INIS)

    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

  7. P Wave Dispersion is Increased in Pulmonary Stenosis

    Directory of Open Access Journals (Sweden)

    Namik Ozmen

    2006-01-01

    Full Text Available Aim: The right atrium pressure load is increased in pulmonary stenosis (PS that is a congenital anomaly and this changes the electrophysiological characteristics of the atria. However, there is not enough data on the issue of P wave dispersion (PWD in PS. Methods: Forty- two patients diagnosed as having valvular PS with echocardiography and 33 completely healthy individuals as the control group were included in the study. P wave duration, p wave maximum (p max and p minimum (p min were calculated from resting electrocariography (ECG obtained at the rate of 50 mm/sec. P wave dispersion was derived by subtracting p min from p max. The mean pressure gradient (MPG at the pulmonary valve, structure of the valve and diameters of the right and left atria were measured with echocardiography. The data from two groups were compared with the Mann-Whitney U test and correlation analysis was performed with the Pearson correlation technique. Results: There wasn’t any statistically significance in the comparison of age, left atrial diameter and p min between two groups. While the MPG at the pulmonary valve was 43.11 ± 18.8 mmHg in PS patients, it was 8.4 ± 4.5 mmHg in the control group. While p max was 107.1 ± 11.5 in PS group, it was 98.2 ± 5.1 in control group (p=0.01, PWD was 40.4 ± 1.2 in PS group, and 27.2 ± 9.3 in the control group (p=0.01Moreover, while the diameter of the right atrium in PS group was greater than that of the control group, (38.7 ± 3.9 vs 30.2 ± 2.5, p=0.02. We detected a correlation between PWD and pressure gradient in regression analysis. Conclusion: P wave dispersion and p max are increased in PS. While PWD was correlated with the pressure gradient that is the degree of narrowing, it was not correlated with the diameters of the right and left atria.

  8. Optical tsunamis: shoaling of shallow water rogue waves in nonlinear fibers with normal dispersion

    International Nuclear Information System (INIS)

    Wabnitz, Stefan

    2013-01-01

    In analogy with ocean waves running up towards the beach, shoaling of pre-chirped optical pulses may occur in the normal group-velocity dispersion regime of optical fibers. We present exact Riemann wave solutions of the optical shallow water equations and show that they agree remarkably well with the numerical solutions of the nonlinear Schrödinger equation, at least up to the point where a vertical pulse front develops. We also reveal that extreme wave events or optical tsunamis may be generated in dispersion tapered fibers in the presence of higher-order dispersion. (paper)

  9. Dispersion relation and Landau damping of waves in high-energy density plasmas

    International Nuclear Information System (INIS)

    Zhu Jun; Ji Peiyong

    2012-01-01

    We present a theoretical investigation on the propagation of electromagnetic waves and electron plasma waves in high energy density plasmas using the covariant Wigner function approach. Based on the covariant Wigner function and Dirac equation, a relativistic quantum kinetic model is established to describe the physical processes in high-energy density plasmas. With the zero-temperature Fermi–Dirac distribution, the dispersion relation and Landau damping of waves containing the relativistic quantum corrected terms are derived. The relativistic quantum corrections to the dispersion relation and Landau damping are analyzed by comparing our results with those obtained in classical and non-relativistic quantum plasmas. We provide a detailed discussion on the Landau damping obtained in classical plasmas, non-relativistic Fermi plasmas and relativistic Fermi plasmas. The contributions of the Bohm potential, the Fermi statistics pressure and relativistic effects to the dispersion relation and Landau damping of waves are quantitatively calculated with real plasma parameters. (paper)

  10. Instability of dust ion-acoustic waves in a dusty plasma containing elongated and rotating charged dust grains

    International Nuclear Information System (INIS)

    Shukla, P.K.; Tskhakaya, D.D.

    2001-01-01

    The dispersion properties of the dust ion-acoustic waves (DIAWs) in an unmagnetized dusty plasma is examined when the plasma constituents are electrons, ions, and charged dust grains which are elongated and rotating. Since the dipole moment of elongated and rotating dust grains is nonzero, significant modifications of the DIAW spectrum emerge. It is found that the DIAWs are subjected to an instability when the DIAW frequency approximately equals the angular rotation frequency of the elongated dust grains. The relevance of our investigation to enhanced fluctuations in space and laboratory dusty plasmas is pointed out

  11. Nonplanar ion acoustic waves with kappa-distributed electrons

    International Nuclear Information System (INIS)

    Sahu, Biswajit

    2011-01-01

    Using the standard reductive perturbation technique, nonlinear cylindrical and spherical Kadomtsev-Petviashvili equations are derived for the propagation of ion acoustic solitary waves in an unmagnetized collisionless plasma with kappa distributed electrons and warm ions. The influence of kappa-distributed electrons and the effects caused by the transverse perturbation on cylindrical and spherical ion acoustic waves (IAWs) are investigated. It is observed that increase in the kappa distributed electrons (i.e., decreasing κ) decreases the amplitude of the solitary electrostatic potential structures. The numerical results are presented to understand the formation of ion acoustic solitary waves with kappa-distributed electrons in nonplanar geometry. The present investigation may have relevance in the study of propagation of IAWs in space and laboratory plasmas.

  12. Propagation of high frequency electrostatic surface waves along the planar interface between plasma and dusty plasma

    Science.gov (United States)

    Mishra, Rinku; Dey, M.

    2018-04-01

    An analytical model is developed that explains the propagation of a high frequency electrostatic surface wave along the interface of a plasma system where semi-infinite electron-ion plasma is interfaced with semi-infinite dusty plasma. The model emphasizes that the source of such high frequency waves is inherent in the presence of ion acoustic and dust ion acoustic/dust acoustic volume waves in electron-ion plasma and dusty plasma region. Wave dispersion relation is obtained for two distinct cases and the role of plasma parameters on wave dispersion is analyzed in short and long wavelength limits. The normalized surface wave frequency is seen to grow linearly for lower wave number but becomes constant for higher wave numbers in both the cases. It is observed that the normalized frequency depends on ion plasma frequencies when dust oscillation frequency is neglected.

  13. Propagation of electro-kinetic waves in magnetized GaN semiconductor with nano-sized ion colloids

    Energy Technology Data Exchange (ETDEWEB)

    Saxena, Ajay [Government College, Garoth, Dist. Mandsaur (M P) (India); Sharma, Giriraj, E-mail: grsharma@gmail.com [SRJ Government Girls’ College, Neemuch (M P) (India); Jat, K. L. [Swami Vivekanand Government P G College, Neemuch (M P) (India); Rishi, M. P. [Shahid Bhagat Singh Government P G College, Jaora, Dist Ratlam (M P) (India)

    2015-07-31

    Based on hydrodynamic model of multi-component plasma, an analytical study on propagation of longitudinal electro-kinetic (LEK) waves in wurtzite and zincblende structures of GaN is carried out. Nano-sized ion colloids (NICs) are embedded in the sample by the technique of ion-implantation. The implanted NICs are considered massive by an order as compared to the host lattice points and do not participate in Based LEK perturbations. Though, the NICs are continuously bombarded by the electrons as well as the holes yet, the former acquires a net negative charge owing to relatively higher mobility of electrons and consequently results into depletion of electron density in the medium. It i s found that the presence of charged NICs significantly modifies the dispersion and amplification characteristics of LEK waves in magnetized GaN semiconductor plasma and their role becomes increasingly effective as the fraction of charge on them increases.

  14. Propagation of electro-kinetic waves in magnetized GaN semiconductor with nano-sized ion colloids

    International Nuclear Information System (INIS)

    Saxena, Ajay; Sharma, Giriraj; Jat, K. L.; Rishi, M. P.

    2015-01-01

    Based on hydrodynamic model of multi-component plasma, an analytical study on propagation of longitudinal electro-kinetic (LEK) waves in wurtzite and zincblende structures of GaN is carried out. Nano-sized ion colloids (NICs) are embedded in the sample by the technique of ion-implantation. The implanted NICs are considered massive by an order as compared to the host lattice points and do not participate in Based LEK perturbations. Though, the NICs are continuously bombarded by the electrons as well as the holes yet, the former acquires a net negative charge owing to relatively higher mobility of electrons and consequently results into depletion of electron density in the medium. It i s found that the presence of charged NICs significantly modifies the dispersion and amplification characteristics of LEK waves in magnetized GaN semiconductor plasma and their role becomes increasingly effective as the fraction of charge on them increases

  15. Dispersion Energy Analysis of Rayleigh and Love Waves in the Presence of Low-Velocity Layers in Near-Surface Seismic Surveys

    Science.gov (United States)

    Mi, Binbin; Xia, Jianghai; Shen, Chao; Wang, Limin

    2018-03-01

    High-frequency surface-wave analysis methods have been effectively and widely used to determine near-surface shear (S) wave velocity. To image the dispersion energy and identify different dispersive modes of surface waves accurately is one of key steps of using surface-wave methods. We analyzed the dispersion energy characteristics of Rayleigh and Love waves in near-surface layered models based on numerical simulations. It has been found that if there is a low-velocity layer (LVL) in the half-space, the dispersion energy of Rayleigh or Love waves is discontinuous and ``jumping'' appears from the fundamental mode to higher modes on dispersive images. We introduce the guided waves generated in an LVL (LVL-guided waves, a trapped wave mode) to clarify the complexity of the dispersion energy. We confirm the LVL-guided waves by analyzing the snapshots of SH and P-SV wavefield and comparing the dispersive energy with theoretical values of phase velocities. Results demonstrate that LVL-guided waves possess energy on dispersive images, which can interfere with the normal dispersion energy of Rayleigh or Love waves. Each mode of LVL-guided waves having lack of energy at the free surface in some high frequency range causes the discontinuity of dispersive energy on dispersive images, which is because shorter wavelengths (generally with lower phase velocities and higher frequencies) of LVL-guided waves cannot penetrate to the free surface. If the S wave velocity of the LVL is higher than that of the surface layer, the energy of LVL-guided waves only contaminates higher mode energy of surface waves and there is no interlacement with the fundamental mode of surface waves, while if the S wave velocity of the LVL is lower than that of the surface layer, the energy of LVL-guided waves may interlace with the fundamental mode of surface waves. Both of the interlacements with the fundamental mode or higher mode energy may cause misidentification for the dispersion curves of surface

  16. Low-frequency waves in magnetized dusty plasmas revisited

    International Nuclear Information System (INIS)

    Salimullah, M.; Khan, M.I.; Amin, R.; Nitta, H.; Shukla, P.K.

    2005-10-01

    The general dispersion relation of any wave is examined for low-frequency waves in a homogeneous dusty plasma in the presence of an external magnetic field. The low-frequency parallel electromagnetic wave propagates as a dust cyclotron wave or a whistler in the frequency range below the ion cyclotron frequency. In the same frequency regime, the transverse electromagnetic magnetosonic wave is modified with a cutoff frequency at the dust-ion lower-hybrid frequency, which reduces to the usual magnetosonic wave in absence of the dust. Electrostatic dust-lower- hybrid mode is also recovered propagating nearly perpendicular to the magnetic field with finite ion temperature and cold dust particles which for strong ion-Larmor radius effect reduces to the usual dust-acoustic wave driven by the ion pressure. (author)

  17. STATISTICALLY DETERMINED DISPERSION RELATIONS OF MAGNETIC FIELD FLUCTUATIONS IN THE TERRESTRIAL FORESHOCK

    International Nuclear Information System (INIS)

    Hnat, B.; O’Connell, D.; Nakariakov, V. M.; Sundberg, T.

    2016-01-01

    We obtain dispersion relations of magnetic field fluctuations for two crossings of the terrestrial foreshock by Cluster spacecraft. These crossings cover plasma conditions that differ significantly in their plasma β and in the density of the reflected ion beam, but not in the properties of the encountered ion population, both showing shell-like distribution function. Dispersion relations are reconstructed using two-point instantaneous wave number estimations from pairs of Cluster spacecraft. The accessible range of wave vectors, limited by the available spacecraft separations, extends to ≈2 × 10 4 km. Results show multiple branches of dispersion relations, associated with different powers of magnetic field fluctuations. We find that sunward propagating fast magnetosonic waves and beam resonant modes are dominant for the high plasma β interval with a dense beam, while the dispersions of the interval with low beam density include Alfvén and fast magnetosonic modes propagating sunward and anti-sunward.

  18. STATISTICALLY DETERMINED DISPERSION RELATIONS OF MAGNETIC FIELD FLUCTUATIONS IN THE TERRESTRIAL FORESHOCK

    Energy Technology Data Exchange (ETDEWEB)

    Hnat, B.; O’Connell, D.; Nakariakov, V. M. [Centre for Fusion, Space and Astrophysics, University of Warwick (United Kingdom); Sundberg, T., E-mail: B.Hnat@warwick.ac.uk [School of Physics and Astronomy, Queen Mary University of London (United Kingdom)

    2016-08-20

    We obtain dispersion relations of magnetic field fluctuations for two crossings of the terrestrial foreshock by Cluster spacecraft. These crossings cover plasma conditions that differ significantly in their plasma β and in the density of the reflected ion beam, but not in the properties of the encountered ion population, both showing shell-like distribution function. Dispersion relations are reconstructed using two-point instantaneous wave number estimations from pairs of Cluster spacecraft. The accessible range of wave vectors, limited by the available spacecraft separations, extends to ≈2 × 10{sup 4} km. Results show multiple branches of dispersion relations, associated with different powers of magnetic field fluctuations. We find that sunward propagating fast magnetosonic waves and beam resonant modes are dominant for the high plasma β interval with a dense beam, while the dispersions of the interval with low beam density include Alfvén and fast magnetosonic modes propagating sunward and anti-sunward.

  19. Parametric study of guided waves dispersion curves for composite plates

    Science.gov (United States)

    Predoi, Mihai Valentin; Petre, Cristian Cǎtǎlin; Kettani, Mounsif Ech Cherif El; Leduc, Damien

    2018-02-01

    Nondestructive testing of composite panels benefit from the relatively long range propagation of guided waves in sandwich structures. The guided waves are sensitive to delamination, air bubbles inclusions and cracks and can thus bring information about hidden defects in the composite panel. The preliminary data in all such inspections is represented by the dispersion curves, representing the dependency of the phase/group velocity on the frequency for the propagating modes. In fact, all modes are more or less attenuated, so it is even more important to compute the dispersion curves, which provide also the modal attenuation as function of frequency. Another important aspect is the sensitivity of the dispersion curves on each of the elastic constant of the composite, which are orthotropic in most cases. All these aspects are investigated in the present work, based on our specially developed finite element numerical model implemented in Comsol, which has several advantages over existing methods. The dispersion curves and modal displacements are computed for an example of composite plate. Comparison with literature data validates the accuracy of our results.

  20. Resonant ion acceleration by collisionless magnetosonic shock waves

    International Nuclear Information System (INIS)

    Ohsawa, Y.

    1985-01-01

    Resonant ion acceleration ( the ν/sub rho/xΒ acceleration ) in laminar magnetosonic shock waves is studied by theory and simulation. Theoretical analysis based on a two-fluid model shows that, in laminar shocks, the electric field strength in the direction of the wave normal is about (m/sub i/m/sub e/) 1 2 times large for quasi-perpendicular shocks than that for the quasi-parallel shocks, which is a reflection of the fact that the width of quasi-perpendicular shocks is much smaller than that of the quasi-parallel shocks. Trapped ions can be accelerated up to the speed about ν/sub A/(m/sub i/m/sub e/) 1 2(M/sub A/-1) 3 2 in quasi-perpendicular shocks. Time evolution of self-consistent magnetosonic shock waves is studied by using a 2-12 dimensional fully relativistic, fully electromagnetic particle simulation with full ion and electron dynamics. Even a low-Mach-number shock wave can significantly accelerate trapped ions by the ν/sub rho/xΒ acceleration. The resonant ion acceleration occurs more strongly in quasi-perpendicular shocks, because the magnitude of this acceleration is proportional to the electric field strength

  1. Comparative study of ion cyclotron waves at Mars, Venus and Earth

    Science.gov (United States)

    Wei, H. Y.; Russell, C. T.; Zhang, T. L.; Blanco-Cano, X.

    2011-08-01

    Ion cyclotron waves are generated in the solar wind when it picks up freshly ionized planetary exospheric ions. These waves grow from the free energy of the highly anisotropic distribution of fresh pickup ions, and are observed in the spacecraft frame with left-handed polarization and a wave frequency near the ion's gyrofrequency. At Mars and Venus and in the Earth's polar cusp, the solar wind directly interacts with the planetary exospheres. Ion cyclotron waves with many similar properties are observed in these diverse plasma environments. The ion cyclotron waves at Mars indicate its hydrogen exosphere to be extensive and asymmetric in the direction of the interplanetary electric field. The production of fast neutrals plays an important role in forming an extended exosphere in the shape and size observed. At Venus, the region of exospheric proton cyclotron wave production may be restricted to the magnetosheath. The waves observed in the solar wind at Venus appear to be largely produced by the solar-wind-Venus interaction, with some waves at higher frequencies formed near the Sun and carried outward by the solar wind to Venus. These waves have some similarity to the expected properties of exospherically produced proton pickup waves but are characterized by magnetic connection to the bow shock or by a lack of correlation with local solar wind properties respectively. Any confusion of solar derived waves with exospherically derived ion pickup waves is not an issue at Mars because the solar-produced waves are generally at much higher frequencies than the local pickup waves and the solar waves should be mostly absorbed when convected to Mars distance as the proton cyclotron frequency in the plasma frame approaches the frequency of the solar-produced waves. In the Earth's polar cusp, the wave properties of ion cyclotron waves are quite variable. Spatial gradients in the magnetic field may cause this variation as the background field changes between the regions in which

  2. Multi-dimensional conversion to the ion-hybrid mode

    International Nuclear Information System (INIS)

    Tracy, E.R.; Kaufman, A.N.; Brizard, A.J.; Morehead, J.J.

    1996-01-01

    We first demonstrate that the dispersion matrix for linear conversion of a magnetosonic wave to an ion-hybrid wave (as in a D-T plasma) can be congruently transformed to Friedland's normal form. As a result, this conversion can be represented as a two-step process of successive linear conversions in phase space. We then proceed to study the multi-dimensional case of tokamak geometry. After fourier transforming the toroidal dependence, we deal with the two-dimensional poloidal xy-plane and the two-dimensional k x k y -plane, forming a four-dimensional phase space. The dispersion manifolds for the magnetosonic wave [D M (x, k) = 0] and the ion-hybrid wave [D H (x, k) = 0] are each three-dimensional. (Their intersection, on which mode conversion occurs, is two-dimensional.) The incident magnetosonic wave (radiated by an antenna) is a two-dimensional set of rays (a lagrangian manifold): k(x) = ∇θ(x), with θ(x) the phase of the magnetosonic wave. When these rays pierce the ion-hybrid dispersion manifold, they convert to a set of ion-hybrid rays. Then, when those rays intersect the magnetosonic dispersion manifold, they convert to a set of open-quotes reflectedclose quotes magnetosonic rays. This set of rays is distinct from the set of incident rays that have been reflected by the inner surface of the tokamak plasma. As a result, the total destructive interference that can occur in the one-dimensional case may become only partial. We explore the implications of this startling phenomenon both analytically and geometrically

  3. Particle dispersion and mixing induced by breaking internal gravity waves

    Science.gov (United States)

    Bouruet-Aubertot, Pascale; Koudella, C.; Staquet, C.; Winters, K. B.

    2001-01-01

    The purpose of this paper is to analyze diapycnal mixing induced by the breaking of an internal gravity wave — the primary wave — either standing or propagating. To achieve this aim we apply two different methods. The first method consists of a direct estimate of vertical eddy diffusion from particle dispersion while the second method relies upon potential energy budgets [Winters, K.B., Lombard, P.N., Riley, J.J., D'Asaro, E.A., 1995. J. Fluid Mech. 289, 115-128; Winters, K.B., D'Asaro, E.A., 1996. J. Fluid Mech. 317, 179-193]. The primary wave we consider is of small amplitude and is statically stable, a case for which the breaking process involves two-dimensional instabilities. The dynamics of the waves have been previously analyzed by means of two-dimensional direct numerical simulations [Bouruet-Aubertot, P., Sommeria, J., Staquet, C., 1995. J. Fluid Mech. 285, 265-301; Bouruet-Aubertot, P., Sommeria, J., Staquet, C., 1996. Dyn. Atmos. Oceans 29, 41-63; Koudella, C., Staquet, C., 1998. In: Davis, P. (Ed.), Proceedings of the IMA Conference on Mixing and Dispersion on Stably-stratified Flows, Dundee, September 1996. IMA Publication]. High resolution three-dimensional calculations of the same wave are also reported here [Koudella, C., 1999]. A local estimate of mixing is first inferred from the time evolution of sets of particles released in the flow during the breaking regime. We show that, after an early evolution dominated by shear effects, a diffusion law is reached and the dispersion coefficient is fairly independent of the initial seeding location of the particles in the flow. The eddy diffusion coefficient, K, is then estimated from the diapycnal diffusive flux. A good agreement with the value inferred from particle dispersion is obtained. This finding is of particular interest regarding the interpretation of in situ estimates of K inferred either from tracer dispersion or from microstructure measurements. Computation of the Cox number, equal to the

  4. Electromagnetic ion cyclotron waves in the plasma depletion layer

    Science.gov (United States)

    Denton, Richard E.; Hudson, Mary K.; Fuselier, Stephen A.; Anderson, Brian J.

    1993-01-01

    Results of a study of the theoretical properties of electromagnetic ion cyclotron (EMIC) waves which occur in the plasma depletion layer are presented. The analysis assumes a homogeneous plasma with the characteristics which were measured by the AMPTE/CCE satellite at 1450-1501 UT on October 5, 1984. Waves were observed in the Pc 1 frequency range below the hydrogen gyrofrequency, and these waves are identified as EMIC waves. The higher-frequency instability is driven by the temperature anisotropy of the H(+) ions, while the lower-frequency instability is driven by the temperature anisotropy of the He(2+) ions. It is argued that the higher-frequency waves will have k roughly parallel to B(0) and will be left-hand polarized, while the lower frequency wave band will have k oblique to B(0) and will be linearly polarized, in agreement with observations.

  5. Effects of temperature and wave conditions on chemical dispersion efficacy of heavy fuel oil in an experimental flow-through wave tank.

    Science.gov (United States)

    Li, Zhengkai; Lee, Kenneth; King, Thomas; Boufadel, Michel C; Venosa, Albert D

    2010-09-01

    The effectiveness of chemical dispersants (Corexit 9500 and SPC 1000) on heavy fuel oil (IFO180 as test oil) has been evaluated under different wave conditions in a flow-through wave tank. The dispersant effectiveness was determined by measuring oil concentrations and droplet size distributions. An analysis of covariance (ANCOVA) model indicated that wave type and temperature significantly (p or = 400 microm). Copyright 2010 Elsevier Ltd. All rights reserved.

  6. Direct measurement of the plasma response to electrostatic ion waves

    International Nuclear Information System (INIS)

    Sarfaty, M.; DeSouza-Machado, S.; Skiff, F.

    1995-01-01

    Plasma wave-wave and wave-particle interactions are studied in a linear magnetized plasma. The relatively quiet plasma is produced by an argon gas-discharge. The plasma density is n e ≅ 10 9 cm -3 and the electron/ion temperatures are T e ≅ 5eV and T i = 0.05eV. A grid and a four ring antenna, both mounted on a scanning carriage, are used to launch electrostatic ion waves in the plasma. Laser Induced Fluorescence measurements of both the linear and the nonlinear plasma response to the wave fields are presented. The Vlasov-Poisson equations are used to explain the measured zero, first and second order terms of the ion distribution function in the presence of wave fields. In addition to the broadening (heating) of the ion distribution as the authors increase the wave amplitudes, induced plasma flows are observed both along and across the magnetic field

  7. Competition between Dispersion and Absorption of Doubly-Dressed Four-Wave Mixing and Dressed Six-Wave Mixing

    International Nuclear Information System (INIS)

    Lei-Jian, Shen; Chuang-She, Li; Yi-Gang, Du; Cui-Cui, Zuo; Zhi-Qiang, Nie; Yan-Peng, Zhang; Yuan-Yuan, Li; Chen-Li, Gan; Ke-Qing, Lu

    2008-01-01

    We study the competition between dispersion and absorption of doubly-dressed four-wave mixing (DDFWM) and dressed six-wave mixing. In the case of weak coupling fields limit, we find DDFWM signal is affected by destructive interference between four-wave mixing(FWM) and six-wave mixing as well as constructive interference between FWM and eight-wave mixing. By analysing the difference between two kinds of doubly dressing mechanisms (parallel cascade and nested cascade) in this opening five-level system, we can further understand the generated high-order nonlinear optical signal dressed by multi-fields

  8. Dispersion calculation method based on S-transform and coordinate rotation for Love channel waves with two components

    Science.gov (United States)

    Feng, Lei; Zhang, Yugui

    2017-08-01

    Dispersion analysis is an important part of in-seam seismic data processing, and the calculation accuracy of the dispersion curve directly influences pickup errors of channel wave travel time. To extract an accurate channel wave dispersion curve from in-seam seismic two-component signals, we proposed a time-frequency analysis method based on single-trace signal processing; in addition, we formulated a dispersion calculation equation, based on S-transform, with a freely adjusted filter window width. To unify the azimuth of seismic wave propagation received by a two-component geophone, the original in-seam seismic data undergoes coordinate rotation. The rotation angle can be calculated based on P-wave characteristics, with high energy in the wave propagation direction and weak energy in the vertical direction. With this angle acquisition, a two-component signal can be converted to horizontal and vertical directions. Because Love channel waves have a particle vibration track perpendicular to the wave propagation direction, the signal in the horizontal and vertical directions is mainly Love channel waves. More accurate dispersion characters of Love channel waves can be extracted after the coordinate rotation of two-component signals.

  9. Oblique Modulation of Ion-Acoustic Waves in a Warm Plasma

    International Nuclear Information System (INIS)

    Xue Jukui; Tang Rongan

    2003-01-01

    The stability of oblique modulation of ion-acoustic waves in an unmagnetized warm plasma is studied. A nonlinear Schroedinger equation governing the slow modulation of the wave amplitude is derived. The effect of temperature on the oblique modulational instability of the ion-acoustic wave is investigated. It is found that the ion temperature significantly changes the domain of the modulational instability in the k-θ plane

  10. Effects of ion-atom collisions on the propagation and damping of ion-acoustic waves

    DEFF Research Database (Denmark)

    Andersen, H.K.; D'Angelo, N.; Jensen, Vagn Orla

    1968-01-01

    Experiments are described on ion-acoustic wave propagation and damping in alkali plasmas of various degrees of ionization. An increase of the ratio Te/Ti from 1 to approximately 3-4, caused by ion-atom collisions, results in a decrease of the (Landau) damping of the waves. At high gas pressure and....../or low wave frequency a "fluid" picture adequately describes the experimental results....

  11. Wave number determination of Pc 1-2 mantle waves considering He++ ions: A Cluster study

    Science.gov (United States)

    Grison, B.; Escoubet, C. P.; Santolík, O.; Cornilleau-Wehrlin, N.; Khotyaintsev, Y.

    2014-09-01

    The present case study concerns narrowband electromagnetic emission detected in the distant cusp region simultaneously with upgoing plasma flows. The wave properties match the usual properties of the Pc 1-2 mantle waves: small angle between the wave vector and the magnetic field line, left-hand polarization, and propagation toward the ionosphere. We report here the first direct wave vector measurement of these waves (about 1.2 × 10- 2 rad/km) through multi spacecraft analysis using the three magnetic components and, at the same time, through single spacecraft analysis based on the refractive index analysis using the three magnetic components and two electric components. The refractive index analysis offers a simple way to estimate wave numbers in this frequency range. Numerical calculations are performed under the observed plasma conditions. The obtained results show that the ion distribution functions are unstable to ion cyclotron instability at the observed wave vector value, due to the large ion temperature anisotropy. We thus show that these electromagnetic ion cyclotron (EMIC) waves are amplified in the distant cusp region. The Poynting flux of the waves is counterstreaming with respect to the plasma flow. This sense of propagation is consistent with the time necessary to amplify the emissions to the observed level. We point out the role of the wave damping at the He++ gyrofrequency to explain that such waves cannot be observed from the ground at the cusp foot print location.

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

    Energy Technology Data Exchange (ETDEWEB)

    El-Tantawy, S.A., E-mail: samireltantawy@yahoo.com

    2017-02-26

    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. - Highlights: • UNPs are modeled by the phenomenological generalized hydrodynamic equations. • The derivative expansion method has been employed in order to derive a modified-NLSE. • A suitable transformation is used to transform the modified-NLSE into the standard NLSE. • The effect of the ion viscosity on the modulational instability and rogue waves is investigated.

  13. Dispersion-Engineered Traveling Wave Kinetic Inductance Parametric Amplifier

    Science.gov (United States)

    Zmuidzinas, Jonas (Inventor); Day, Peter K. (Inventor)

    2014-01-01

    A traveling wave kinetic inductance parametric amplifier comprises a superconducting transmission line and a dispersion control element. The transmission line can include periodic variations of its dimension along its length. The superconducting material can include a high normal state resistivity material. In some instances the high normal state resistivity material includes nitrogen and a metal selected from the group consisting of titanium, niobium and vanadium. The traveling wave kinetic inductance parametric amplifier is expected to exhibit a noise temperature below 100 mK/GHz.

  14. EXPERIMENTAL DETERMINATION OF WHISTLER WAVE DISPERSION RELATION IN THE SOLAR WIND

    Energy Technology Data Exchange (ETDEWEB)

    Stansby, D.; Horbury, T. S.; Chen, C. H. K.; Matteini, L., E-mail: david.stansby14@imperial.ac.uk [Department of Physics, Imperial College London, London SW7 2AZ (United Kingdom)

    2016-09-20

    The origins and properties of large-amplitude whistler wavepackets in the solar wind are still unclear. In this Letter, we utilize single spacecraft electric and magnetic field waveform measurements from the ARTEMIS mission to calculate the plasma frame frequency and wavevector of individual wavepackets over multiple intervals. This allows direct comparison of experimental measurements with theoretical dispersion relations to identify the observed waves as whistler waves. The whistlers are right-hand circularly polarized, travel anti-sunward, and are aligned with the background magnetic field. Their dispersion is strongly affected by the local electron parallel beta in agreement with linear theory. The properties measured are consistent with the electron heat flux instability acting in the solar wind to generate these waves.

  15. Interaction between counter-streaming ion-acoustic solitons and the Langmuir waves

    International Nuclear Information System (INIS)

    Basovich, A.Ya.; Gromov, E.M.; Talanov, V.I.

    1984-01-01

    The interaction between strong counter-streaming ion-acoustic solitons and the Langmuir waves is considered. At first the Langmuir waves spectrum transformation by counter-streaming ion-acoustic solutions of a preset amplitude e has been found. An increase in the frequency and number of the Langmuir waves due to the Doppler effect in the course of multiple reflection from the f front soliton slope has been determined and the wave number range in which the confinement of the Langmuir waves by counter-streaning solitons is possible has s been found. It is shown that the time of the Langmuir wave transformation into the short-wave region under the effect of the counter-streaming soliton may y be short as compared with the time of the Langmuir wave diffusion into the Landau damping region under the effect of random fields of ion-acoustic waves. In the adiabatic fpproximation changes in the counter-streaming ion acoustic parameters of solitons owing to the Langmuir waves have been

  16. Fundamental plasma emission involving ion sound waves

    International Nuclear Information System (INIS)

    Cairns, I.H.

    1987-01-01

    The theory for fundamental plasma emission by the three-wave processes L ± S → 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. (author)

  17. Evaluation of QT and P wave dispersion and mean platelet volume among inflammatory bowel disease patients.

    Science.gov (United States)

    Dogan, Yuksel; Soylu, Aliye; Eren, Gulay A; Poturoglu, Sule; Dolapcioglu, Can; Sonmez, Kenan; Duman, Habibe; Sevindir, Isa

    2011-01-01

    In inflammatory bowel disease (IBD) number of thromboembolic events are increased due to hypercoagulupathy and platelet activation. Increases in mean platelet volume (MPV) can lead to platelet activation, this leads to thromboembolic events and can cause acute coronary syndromes. In IBD patients, QT-dispersion and P-wave dispersion are predictors of ventricular arrhythmias and atrial fibrilation; MPV is accepted as a risk factor for acute coronary syndromes, we aimed at evaluating the correlations of these with the duration of disease, its localization and activity. The study group consisted of 69 IBD (Ulcerative colitis n: 54, Crohn's Disease n: 15) patients and the control group included 38 healthy individuals. Disease activity was evaluated both endoscopically and clinically. Patients with existing cardiac conditions, those using QT prolonging medications and having systemic diseases, anemia and electrolyte imbalances were excluded from the study. QT-dispersion, P-wave dispersion and MPV values of both groups were compared with disease activity, its localization, duration of disease and the antibiotics used. The P-wave dispersion values of the study group were significantly higher than those of the control group. Duration of the disease was not associated with QT-dispersion, and MPV levels. QT-dispersion, P-wave dispersion, MPV and platelet count levels were similar between the active and in mild ulcerative colitis patients. QT-dispersion levels were similar between IBD patients and the control group. No difference was observed between P-wave dispersion, QT-dispersion and MPV values; with regards to disease duration, disease activity, and localization in the study group (p>0.05). P-wave dispersion which is accepted as a risk factor for the development of atrial fibirilation was found to be high in our IBD patients. This demonstrates us that the risk of developing atrial fibrillation may be high in patients with IBD. No significant difference was found in the QT-dispersion

  18. Electron Acoustic Waves in Pure Ion Plasmas

    Science.gov (United States)

    Anderegg, F.; Driscoll, C. F.; Dubin, D. H. E.; O'Neil, T. M.

    2009-11-01

    Electron Acoustic Waves (EAW) are the low frequency branch of electrostatic plasma waves. These waves exist in neutralized plasmas, pure electron plasmas and in pure ion plasmasfootnotetextF. Anderegg et al., PRL 102, 095001 (2009) and PoP 16, 055705 (2009). (where the name is deceptive). Here, we observe standing mθ= 0 mz= 1 EAWs in a pure ion plasma column. At small amplitude, the EAWs have a phase velocity vph ˜1.4 v, and the frequencies are in close agreement with theory. At moderate amplitudes, waves can be excited over a broad range of frequencies, with observed phase velocities in the range of 1.4 v vph diagnostic shows that particles slower than vph oscillate in phase with the wave, while particles moving faster than vph oscillate 180^o out of phase with the wave. From a fluid perspective, this gives an unusual negative dynamical compressibility. That is, the wave pressure oscillations are 180^o out of phase from the density oscillations, almost fully canceling the electrostatic restoring force, giving the low and malleable frequency.

  19. Longitudinal ultrasonic waves dispersion in bars

    International Nuclear Information System (INIS)

    Suarez Antola, R.

    2001-01-01

    The exhibition intends to review some aspects of the propagation of the longitudinal ultrasonic pulses shortly in bars of traverse section uniform.Aspects they are part of the denominated geometric dispersion of the pulses.This phenomenon It can present like an additional complication in the ultrasonic essay of low frequency of thin pieces in structures and machines but takes place former ex professed in some applications of the wave guides been accustomed to in the prosecution of signs

  20. Cluster observations of ion dispersion discontinuities in the polar cusp

    Science.gov (United States)

    Escoubet, C. P.; Berchem, J.; Pitout, F.; Richard, R. L.; Trattner, K. J.; Grison, B.; Taylor, M. G.; Masson, A.; Dunlop, M. W.; Dandouras, I. S.; Reme, H.; Fazakerley, A. N.

    2009-12-01

    The reconnection between the interplanetary magnetic field (IMF) and the Earth’s magnetic field is taking place at the magnetopause on magnetic field lines threading through the polar cusp. When the IMF is southward, reconnection occurs near the subsolar point, which is magnetically connected to the equatorward boundary of the polar cusp. Subsequently the ions injected through the reconnection point precipitate in the cusp and are dispersed poleward. If reconnection is continuous and operates at constant rate, the ion dispersion is smooth and continuous. On the other hand if the reconnection rate varies, we expect interruption in the dispersion forming energy steps or staircase. Similarly, multiple entries near the magnetopause could also produce steps at low or mid-altitude when a spacecraft is crossing subsequently the field lines originating from these multiple sources. In addition, motion of the magnetopause induced by solar wind pressure changes or erosion due to reconnection can also induce a motion of the polar cusp and a disruption of the ions dispersion observed by a spacecraft. Cluster with four spacecraft following each other in the mid-altitude cusp can be used to distinguish between these “temporal” and “spatial” effects. We will present a cusp crossing with two spacecraft, separated by around two minutes. The two spacecraft observed a very similar dispersion with a step in energy in its centre and two other dispersions poleward. We will show that the steps could be temporal (assuming that the time between two reconnection bursts corresponds to the time delay between the two spacecraft) but it would be a fortuitous coincidence. On the other hand the steps and the two poleward dispersions could be explained by spatial effects if we take into account the motion of the open-closed boundary between the two spacecraft crossings.

  1. On the relationship between magnetostatic wave energy and dispersion characteristics in ferrite structures

    International Nuclear Information System (INIS)

    Vashkovsky, Anatolii V; Lock, Edwin H

    2011-01-01

    The energy and dispersion characteristics of a dipole spin wave in a ferrite-dielectric-metal structure are calculated. An analysis of spin wave dispersion characteristics with extreme points demonstrates how fundamental relationships among the propagation constant, phase and group velocities, Poynting vector, and power flux manifest themselves when the wavenumber changes near these points. A comparison of magnetostatic approximation results with calculations using Maxwell's equations shows the inadequacy of the magnetostatic approximation formulas currently used for calculating the Poynting vector and power flux of dipole spin waves. A correct alternative is proposed. (methodological notes)

  2. Traveling waves in a delayed SIR model with nonlocal dispersal and nonlinear incidence

    Science.gov (United States)

    Zhang, Shou-Peng; Yang, Yun-Rui; Zhou, Yong-Hui

    2018-01-01

    This paper is concerned with traveling waves of a delayed SIR model with nonlocal dispersal and a general nonlinear incidence. The existence and nonexistence of traveling waves of the system are established respectively by Schauder's fixed point theorem and two-sided Laplace transform. It is also shown that the spread speed c is influenced by the dispersal rate of the infected individuals and the delay τ.

  3. Dispersion durations of P-wave and QT interval in children treated with a ketogenic diet.

    Science.gov (United States)

    Doksöz, Önder; Güzel, Orkide; Yılmaz, Ünsal; Işgüder, Rana; Çeleğen, Kübra; Meşe, Timur

    2014-04-01

    Limited data are available on the effects of a ketogenic diet on dispersion duration of P-wave and QT-interval measures in children. We searched for the changes in these measures with serial electrocardiograms in patients treated with a ketogenic diet. Twenty-five drug-resistant patients with epilepsy treated with a ketogenic diet were enrolled in this study. Electrocardiography was performed in all patients before the beginning and at the sixth month after implementation of the ketogenic diet. Heart rate, maximum and minimum P-wave duration, P-wave dispersion, and maximum and minimum corrected QT interval and QT dispersion were manually measured from the 12-lead surface electrocardiogram. Minimum and maximum corrected QT and QT dispersion measurements showed nonsignificant increase at month 6 compared with baseline values. Other previously mentioned electrocardiogram parameters also showed no significant changes. A ketogenic diet of 6 months' duration has no significant effect on electrocardiogram parameters in children. Further studies with larger samples and longer duration of follow-up are needed to clarify the effects of ketogenic diet on P-wave dispersion and corrected QT and QT dispersion. Copyright © 2014 Elsevier Inc. All rights reserved.

  4. Dynamics of beam-driven Langmuir and ion-acoustic waves including electrostatic decay

    International Nuclear Information System (INIS)

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

    2003-01-01

    The evolution of Langmuir waves and ion-acoustic waves stimulated by a hot electron beam in an initially homogeneous plasma is investigated numerically in time, position, and wave number space. Quasilinear interactions between the beam particles and Langmuir waves, nonlinear interactions between the Langmuir and ion-acoustic waves through Langmuir decay processes, and spontaneous emission are taken into account in the kinetic theory employed. For illustrative parameters of those in the solar wind near 1 a.u., nonlinear Langmuir decays are observed to transfer the beam-driven Langmuir waves rapidly out of resonance. The scattered Langmuir waves then undergo further decays, moving sequentially toward small wave numbers, until decay is kinematically prohibited. The main features of the evolution of Langmuir and ion-acoustic waves are spatially inhomogeneous. The scattered Langmuir spectra increase and eventually reach or exceed the beam-driven Langmuir spectra at a given spatial location (except in regions where further decays proceed). The ion-acoustic waves are relatively weak and subject to damping at the later stages of their evolution. The development of fine structures in the product Langmuir and ion-acoustic waves are observed, due to depletion of their energy by decay and dominant damping effects, respectively. The propagation of the beam is essentially unaffected by the operation of the decay process. The decay process is thus slaved to the primary beam-plasma evolution, as assumed in previous studies. A variation of the ratio of electron temperature to ion temperature is found to affect not only the ion-acoustic wave levels through effects on the damping rate, but also the dynamics of decay via effects on the decay rate. The latter was not addressed in previous studies. Furthermore, spontaneous emission of ion-acoustic waves is found to affect the dynamics of decay, thus its inclusion is necessary to correctly model the Langmuir and ion-acoustic spectra

  5. MAGNETOACOUSTIC WAVES IN A PARTIALLY IONIZED TWO-FLUID PLASMA

    Energy Technology Data Exchange (ETDEWEB)

    Soler, Roberto; Ballester, Jose Luis [Departament de Física, Universitat de les Illes Balears, E-07122 Palma de Mallorca (Spain); Carbonell, Marc, E-mail: roberto.soler@uib.es, E-mail: joseluis.ballester@uib.es, E-mail: marc.carbonell@uib.es [Departament de Matemàtiques i Informàtica, Universitat de les Illes Balears, E-07122 Palma de Mallorca (Spain)

    2013-11-01

    Compressible disturbances propagate in a plasma in the form of magnetoacoustic waves driven by both gas pressure and magnetic forces. In partially ionized plasmas the dynamics of ionized and neutral species are coupled due to ion-neutral collisions. As a consequence, magnetoacoustic waves propagating through a partially ionized medium are affected by ion-neutral coupling. The degree to which the behavior of the classic waves is modified depends on the physical properties of the various species and on the relative value of the wave frequency compared to the ion-neutral collision frequency. Here, we perform a comprehensive theoretical investigation of magnetoacoustic wave propagation in a partially ionized plasma using the two-fluid formalism. We consider an extensive range of values for the collision frequency, ionization ratio, and plasma β, so that the results are applicable to a wide variety of astrophysical plasmas. We determine the modification of the wave frequencies and study the frictional damping due to ion-neutral collisions. Approximate analytic expressions for the frequencies are given in the limit case of strongly coupled ions and neutrals, while numerically obtained dispersion diagrams are provided for arbitrary collision frequencies. In addition, we discuss the presence of cutoffs in the dispersion diagrams that constrain wave propagation for certain combinations of parameters. A specific application to propagation of compressible waves in the solar chromosphere is given.

  6. MAGNETOACOUSTIC WAVES IN A PARTIALLY IONIZED TWO-FLUID PLASMA

    International Nuclear Information System (INIS)

    Soler, Roberto; Ballester, Jose Luis; Carbonell, Marc

    2013-01-01

    Compressible disturbances propagate in a plasma in the form of magnetoacoustic waves driven by both gas pressure and magnetic forces. In partially ionized plasmas the dynamics of ionized and neutral species are coupled due to ion-neutral collisions. As a consequence, magnetoacoustic waves propagating through a partially ionized medium are affected by ion-neutral coupling. The degree to which the behavior of the classic waves is modified depends on the physical properties of the various species and on the relative value of the wave frequency compared to the ion-neutral collision frequency. Here, we perform a comprehensive theoretical investigation of magnetoacoustic wave propagation in a partially ionized plasma using the two-fluid formalism. We consider an extensive range of values for the collision frequency, ionization ratio, and plasma β, so that the results are applicable to a wide variety of astrophysical plasmas. We determine the modification of the wave frequencies and study the frictional damping due to ion-neutral collisions. Approximate analytic expressions for the frequencies are given in the limit case of strongly coupled ions and neutrals, while numerically obtained dispersion diagrams are provided for arbitrary collision frequencies. In addition, we discuss the presence of cutoffs in the dispersion diagrams that constrain wave propagation for certain combinations of parameters. A specific application to propagation of compressible waves in the solar chromosphere is given

  7. Dynamics of Dispersive Wave Generation in Gas-Filled Photonic Crystal Fiber with the Normal Dispersion

    Directory of Open Access Journals (Sweden)

    Zhixiang Deng

    2017-01-01

    Full Text Available The absence of Raman and unique pressure-tunable dispersion is the characteristic feature of gas-filled photonic crystal fiber (PCF, and its zero dispersion points can be extended to the near-infrared by increasing gas pressure. The generation of dispersive wave (DW in the normal group velocity dispersion (GVD region of PCF is investigated. It is demonstrated that considering the self-steepening (SS and introducing the chirp of the initial input pulse are two suitable means to control the DW generation. The SS enhances the relative average intensity of blue-shift DW while weakening that of red-shift DW. The required propagation distance of DW emission is markedly varied by introducing the frequency chirp. Manipulating DW generation in gas-filled PCF by the combined effects of either SS or chirp and three-order dispersion (TOD provides a method for a concentrated transfer of energy into the targeted wavelengths.

  8. Effects of ion acoustic waves on diffusion in a magnetized plasma

    International Nuclear Information System (INIS)

    Watanabe, Yukio; Akazaki, Masanori; Fujiyama, Hiroshi.

    1975-01-01

    This paper describes on the behavior of ion acoustic waves in magnetized plasma. The plasma was produced with a discharge tube placed in an air-core coil. The pressure of argon gas in the discharge tube was 1--10 mTorr. The plasma was entracted along the externally applied magnetic field through a nozzle into a measuring part. The condition of stabilization of drift waves was investigated. Four small glass tubes were placed in contact with the wall of the discharge tube, and the drift wave was remarkably suppressed. Then the ion acoustic waves can be observed. The magnetic field dependence of the frequency of ion acoustic waves was studied. The frequency depends on magnetic field and gas pressure. The magnetic field dependence of the frequency is caused by the variation of electron temperature. The Timofee's theory can explain the magnetic field of generating ion acoustic waves. The ion acoustic waves being excited naturally propagate to the direction of the diamagnetic drift of electrons, and their spectra are monochromatic. The dependence of Dsub(perpendicular), diffusion constant, on magnetic field is explained by two-pole diffusion, and the effect of the monochromatic ion acoustic waves on diffusion is small. (Kato, T.)

  9. Role of lower hybrid waves in ion heating at dipolarization fronts

    Science.gov (United States)

    Greco, A.; Artemyev, A.; Zimbardo, G.; Angelopoulos, V.; Runov, A.

    2017-05-01

    One of the important sources of hot ions in the magnetotail is the bursty bulk flows propagating away from the reconnection region and heating the ambient plasma. Charged particles interact with nonlinear magnetic field pulses (dipolarization fronts, DFs) embedded into these flows. The convection electric fields associated with DF propagation are known to reflect and accelerate ambient ions. Moreover, a wide range of waves is observed within/near these fronts, the electric field fluctuations being dominated by the lower hybrid drift (LHD) instability. Here we investigate the potential role of these waves in the further acceleration of ambient ions. We use a LHD wave emission profile superimposed on the leading edge of a two-dimensional model profile of a DF and a test particle approach. We show that LHD waves with realistic amplitudes can significantly increase the upper limit of energies gained by ions. Wave-particle interaction near the front is more effective in producing superthermal ions than in increasing the flux of thermal ions. Comparison of test particle simulations and Time History of Events and Macroscale Interactions during Substorms observations show that ion acceleration by LHD waves is more important for slower DFs.

  10. Strongly nonlinear evolution of low-frequency wave packets in a dispersive plasma

    Science.gov (United States)

    Vasquez, Bernard J.

    1993-01-01

    The evolution of strongly nonlinear, strongly modulated wave packets is investigated in a dispersive plasma using a hybrid numerical code. These wave packets have amplitudes exceeding the strength of the external magnetic field, along which they propagate. Alfven (left helicity) wave packets show strong steepening for p Schrodinger (DNLS) equation.

  11. Universal instability of dust ion-sound waves and dust-acoustic waves

    International Nuclear Information System (INIS)

    Tsytovich, V.N.; Watanabe, K.

    2002-01-01

    It is shown that the dust ion-sound waves (DISW) and the dust-acoustic waves (DAW) are universally unstable for wave numbers less than some critical wave number. The basic dusty plasma state is assumed to be quasi-neutral with balance of the plasma particle absorption on the dust particles and the ionization with the rate proportional to the electron density. An analytical expression for the critical wave numbers, for the frequencies and for the growth rates of DISW and DAW are found using the hydrodynamic description of dusty plasma components with self-consistent treatment of the dust charge variations and by taking into account the change of the ion and electron distributions in the dust charging process. Most of the previous treatment do not take into account the latter process and do not treat the basic state self-consistently. The critical lengths corresponding to these critical wave numbers can be easily achieved in the existing experiments. It is shown that at the wave numbers larger than the critical ones DISW and DAW have a large damping which was not treated previously and which can be also measured. The instabilities found in the present work on their non linear stage can lead to formation of different types of dust self-organized structures. (author)

  12. Ion-Acoustic Cnoidal Waves In A Plasma With Negative Ions

    International Nuclear Information System (INIS)

    Yadav, Lakhan Lal

    2003-01-01

    Using the reductive perturbation method, we present a theory of different nonlinear periodic waves, viz. the Korteweg-de Vries and modified KdV (mKdV) cnoidal waves, in a plasma with negative ions, which in the limiting case reduce to localized structures, namely KdV compressive or rarefactive solitons, and mKdV compressive and rarefactive solitons, respectively. It is found that the amplitude dependence of frequency is different for KdV and mKdV cnoidal waves

  13. Creation evidence of the second non-dispersive Zakharenko wave ...

    Indian Academy of Sciences (India)

    create the third non-dispersive Zakharenko wave [1] (the positive roton or fourth sound) by ..... ('thermal phonons' or 'resistive phonons') instead of 'negative rotons' in the liquid ... the energy conservation law that allow us to state that such BEE ...

  14. Ion temperature effect on the propagation of ion acoustic solitary waves in a relativistic magnetoplasma

    International Nuclear Information System (INIS)

    Salahuddin, M.

    1990-01-01

    Using the reductive perturbation technique the Korteweg-de Vries (KdV) equation is derived for ion acoustic waves, in the presence of weak relativistic effects and warm ions, in a magnetized plasma. The influence of non ideal effects on the amplitude and width of the ion acoustic solitary waves is also discussed. The results are depicted in the figures. It is shown that the simultaneous presence of ion streaming and magnetic field stops the tendency of soliton breaking. (author)

  15. Investigation of Ion Acoustic Waves in Collisionless Plasmas

    DEFF Research Database (Denmark)

    Christoffersen, G. B.; Jensen, Vagn Orla; Michelsen, Poul

    1974-01-01

    The Green's functions for the linearized ion Vlasov equation with a given boundary value are derived. The propagation properties of ion acoustic waves are calculated by performing convolution integrals over the Green's functions. For Te/Ti less than about 3 it is concluded that the collective...... interaction is very weak and that the propagation properties are determined almost completely by freely streaming ions. The wave damping, being due to phase mixing, is determined by the width of the perturbed distribution function rather than by the slope of the undisturbed distribution function at the phase...

  16. Effect of ion composition on oblique magnetosonic waves

    International Nuclear Information System (INIS)

    Kondo, Yuichi; Toida, Mieko

    2011-01-01

    The effects of ion composition on oblique magnetosonic waves in a two-ion-species plasma are studied theoretically and numerically. First, it is analytically shown that the KdV equation for the low-frequency mode, the lower branch of magnetosonic waves, is valid for amplitudes ε max (l-) , where ε max (l-) is a measure of the upper limit of the amplitude of the rarefactive solitary pulse of the low-frequency mode and is given as a function of the propagation angle of the wave θ, the density ratio and cyclotron frequency ratio of two ion species. The value of ε max (l-) increases with decreasing θ. Next, with electromagnetic particle simulations, the nonlinear evolution of the low- and high-frequency modes is examined. It is demonstrated that shorter-wavelength low- and high-frequency-mode waves are generated from a long-wavelength low-frequency-mode pulse if its amplitude ε exceeds ε max (l-) . (author)

  17. Closure of multi-fluid and kinetic equations for cyclotron-resonant interactions of solar wind ions with Alfvén waves

    Directory of Open Access Journals (Sweden)

    E. Marsch

    1998-01-01

    Full Text Available Based on quasilinear theory, a closure scheme for anisotropic multi-component fluid equations is developed for the wave-particle interactions of ions with electromagnetic Alfvén and ion-cyclotron waves propagating along the mean magnetic field. Acceleration and heating rates are calculated. They may be used in the multi-fluid momentum and energy equations as anomalous transport terms. The corresponding evolution equation for the average wave spectrum is established, and the effective growth/damping rate for the spectrum is calculated. Given a simple power-law spectrum, an anomalous collision frequency can be derived which depends on the slope and average intensity of the spectrum, and on the gyrofrequency and the differential motion (with respect to the wave frame of the actual ion species considered. The wave-particle interaction terms attain simple forms resembling the ones for collisional friction and temperature anisotropy relaxation (due to pitch angle scattering with collision rates that are proportional to the gyrofrequency but diminished substantially by the relative wave energy or the fluctuation level with respect the background field. In addition, a set of quasilinear diffusion equations is derived for the reduced (with respect to the perpendicular velocity component velocity distribution functions (VDFs, as they occur in the wave dispersion equation and the related dielectric function for parallel propagation. These reduced VDFs allow one to describe adequately the most prominent observed features, such as an ion beam and temperature anisotropy, in association with the resonant interactions of the particles with the waves on a kinetic level, yet have the advantage of being only dependent upon the parallel velocity component.

  18. Dispersion relation of test waves in an electron beam plasma system

    International Nuclear Information System (INIS)

    Hayashi, N.; Tanaka, M.; Shinohara, S.; Kawai, Y.

    1994-01-01

    Test waves are propagated in an electron beam plasma system and the dispersion relation is measured. At the center of the experimental region a beam mode is excited. Near the chamber wall an electron plasma wave is excited and propagates from the chamber wall to the center of the experimental region. It is also found that observed unstable waves are standing wave which is formed by superposing the beam modes propagating in the opposite directions each other. (author). 6 refs, 6 figs

  19. Energization of helium ions by proton-induced hydromagnetic waves

    International Nuclear Information System (INIS)

    Gendrin, R.; Roux, A.

    1980-01-01

    We consider the diffusion of He + ions under the influence of ion cyclotron waves generated in a plasma consisting of three different ion populations: a thermal isotropic population containing both H + and He + ions and an energetic H + population, with a positive anisotropy A=T/sub perpendicular//T/sub parallel/-1. We compute, in the velocity space upsilon/sub parallel/, upsilon/sub perpendicular/, the diffusion curves that He + ions will follow in the presence of ion cyclotron waves propagating in such a medium. We show that for small concentrations of the He + ions, of the order of 1 to approx.10%, these ions can be energized by such a process up to and above suprathermal energies (E> or approx. =20 eV). On some occasions the He + ions may even reach energies of the order of the Alfven energy of the cold plasma population: E/sub a/approx. =m/sub p/V/sub a/ 2 approx. =5 keV. Characteristic diffusion times, in pitch angle and energy, for both ion species, are evaluated. They are of the order of 2 to 20 min. These theoretical results are discussed in the frame of recent observations by Geos experimenters showing the close association that exists between the occurrence of ion cyclotron ULF waves and the presence of thermal or supra-thermal He + ions in the equatorial region of the magnetosphere

  20. Dynamical chaos of plasma ions in electrostatic waves

    International Nuclear Information System (INIS)

    Fasoli, A.; Kleiber, R.; Tran, M.Q.; Paris, P.J.; Skiff, F.

    1992-09-01

    Chaos generated by the interaction between charged particles and electrostatic plasma waves has been observed in a linear magnetized plasma. The macroscopic wave properties, the kinetic ion dielectric response and the microscopic heating mechanisms have been investigated via optical diagnostic techniques based on laser induced fluorescence. Observations of test-particle dynamical evolution indicate an exponential separation of initially close ion trajectories. (author) 5 figs., 20 refs

  1. Nonlinear surface Alfven waves

    International Nuclear Information System (INIS)

    Cramer, N.F.

    1991-01-01

    The problem of nonlinear surface Alfven waves propagating on an interface between a plasma and a vacuum is discussed, with dispersion provided by the finite-frequency effect, i.e. the finite ratio of the frequency to the ion-cyclotron frequency. A set of simplified nonlinear wave equations is derived using the method of stretched co-ordinates, and another approach uses the generation of a second-harmonic wave and its interaction with the first harmonic to obtain a nonlinear dispersion relation. A nonlinear Schroedinger equation is then derived, and soliton solutions found that propagate as solitary pulses in directions close to parallel and antiparallel to the background magnetic field. (author)

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

    Energy Technology Data Exchange (ETDEWEB)

    Ata-ur-Rahman,; Qamar, A. [Institute of Physics and Electronics, University of Peshawar, Peshawar 25000 (Pakistan); National Centre for Physics, QAU Campus, Shahdrah Valley Road, Islamabad 44000 (Pakistan); Ali, S. [National Centre for Physics, QAU Campus, Shahdrah Valley Road, Islamabad 44000 (Pakistan); Mirza, Arshad M. [Theoretical Plasma Physics Group, Physics Department, Quaid-i-Azam University, Islamabad 45320 (Pakistan)

    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.

  3. The nonlinear effects on the characteristics of gravity wave packets: dispersion and polarization relations

    Directory of Open Access Journals (Sweden)

    S.-D. Zhang

    2000-10-01

    Full Text Available By analyzing the results of the numerical simulations of nonlinear propagation of three Gaussian gravity-wave packets in isothermal atmosphere individually, the nonlinear effects on the characteristics of gravity waves are studied quantitatively. The analyses show that during the nonlinear propagation of gravity wave packets the mean flows are accelerated and the vertical wavelengths show clear reduction due to nonlinearity. On the other hand, though nonlinear effects exist, the time variations of the frequencies of gravity wave packets are close to those derived from the dispersion relation and the amplitude and phase relations of wave-associated disturbance components are consistent with the predictions of the polarization relation of gravity waves. This indicates that the dispersion and polarization relations based on the linear gravity wave theory can be applied extensively in the nonlinear region.Key words: Meteorology and atmospheric dynamics (middle atmosphere dynamics; waves and tides

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

    International Nuclear Information System (INIS)

    Cartier, S.L.; D'Angelo, 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> or approx. =f/sub c/i, where f/sub c/i 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

  5. Electromagnetic drift waves dispersion for arbitrarily collisional plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Wonjae, E-mail: wol023@ucsd.edu; Krasheninnikov, Sergei I., E-mail: skrash@mae.ucsd.edu [Department of Mechanical and Aerospace Engineering, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093 (United States); Angus, J. R. [Naval Research Laboratory, 4555 Overlook Avenue, Washington, DC 20375 (United States)

    2015-07-15

    The impacts of the electromagnetic effects on resistive and collisionless drift waves are studied. A local linear analysis on an electromagnetic drift-kinetic equation with Bhatnagar-Gross-Krook-like collision operator demonstrates that the model is valid for describing linear growth rates of drift wave instabilities in a wide range of plasma parameters showing convergence to reference models for limiting cases. The wave-particle interactions drive collisionless drift-Alfvén wave instability in low collisionality and high beta plasma regime. The Landau resonance effects not only excite collisionless drift wave modes but also suppress high frequency electron inertia modes observed from an electromagnetic fluid model in collisionless and low beta regime. Considering ion temperature effects, it is found that the impact of finite Larmor radius effects significantly reduces the growth rate of the drift-Alfvén wave instability with synergistic effects of high beta stabilization and Landau resonance.

  6. Effects of positron density and temperature on large amplitude ion-acoustic waves in an electron-positron-ion plasma

    International Nuclear Information System (INIS)

    Nejoh, Y.N.

    1997-01-01

    The nonlinear wave structures of large amplitude ion-acoustic waves are studied in a plasma with positrons. We have presented the region of existence of the ion-acoustic waves by analysing the structure of the pseudopotential. The region of existence sensitively depends on the positron to electron density ratio, the ion to electron mass ratio and the positron to electron temperature ratio. It is shown that the maximum Mach number increases as the positron temperature increases and the region of existence of the ion-acoustic waves spreads as the positron temperature increases. 12 refs., 6 figs

  7. Nonlinear modulation of ion acoustic waves in a magnetized plasma

    International Nuclear Information System (INIS)

    Bharuthram, R.; Shukla, P.K.

    1987-01-01

    The quasistatic plasma slow response to coherent ion acoustic waves in a magnetized plasma is considered. A multidimensional cubic nonlinear Schroedinger equation is derived. It is found that the ion acoustic waves remain modulationally stable against oblique perturbations

  8. Effects of dust size distribution on dust acoustic waves in magnetized two-ion-temperature dusty plasmas

    International Nuclear Information System (INIS)

    Liu Zongming; Duan Wenshan; He Guangjun

    2008-01-01

    A Zakharov-Kuznetsov (ZK) equation, a modified ZK (mZK) equation, and a coupled ZK (cZK) equation for small but finite amplitude dust acoustic waves in a magnetized two-ion-temperature dusty plasma with dust size distribution have been investigated in this paper. The variations of the linear dispersion relation and group velocity, nonlinear solitary wave amplitude, and width with an arbitrary dust size distribution function are studied numerically. We conclude that they all increase as the total number density of dust grains increases, and they are greater for unusual dusty plasma (the number density of larger dust grains is greater than that of smaller dust grains) than that of usual dusty plasma (the number density of smaller dust grains is greater than that of larger dust grains). It is noted that the frequency of the linear wave increases as the wave number along the magnetic direction increases. Furthermore, the width of the nonlinear waves increases but its amplitude decreases as the wave number along the magnetic direction increases

  9. On the propagation of truncated localized waves in dispersive silica

    KAUST Repository

    Salem, Mohamed; Bagci, Hakan

    2010-01-01

    Propagation characteristics of truncated Localized Waves propagating in dispersive silica and free space are numerically analyzed. It is shown that those characteristics are affected by the changes in the relation between the transverse spatial

  10. Observation of large-amplitude ion acoustic solitary waves in a plasma

    International Nuclear Information System (INIS)

    Nakamura, Yoshiharu

    1987-01-01

    Propagation of nonlinear ion acoustic waves in a multi-component plasma with negative ions is investigated in a double-plasma device. When the density of negative ions is larger than a critical value, a broad negative pulse evolves to rarefactive solitons, and a positive pulse whose amplitude is less than a certain threshold value becomes a subsonic wave train. In the same plasma, a positive pulse whose amplitude is larger than the threshold develops into a solitary wave. The critical amplitude is measured as a function of the density of negative ions and compared with predictions of the pseudo-potential method. The energy distribution of electrons in the solitary wave is also measured. (author)

  11. Anomalous dispersion properties of TM waves in subwavelength metallic waveguides loaded by uniaxial metamaterials

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Guanghui, E-mail: wanggh@scnu.edu.cn; Lei, Yuandong; Zhang, Weifeng

    2015-02-20

    Dispersion properties of transverse magnetic (TM) waves in a subwavelength metallic waveguide loaded by uniaxial metamaterials are investigated, based on two kinds of uniaxial metamaterials with different orientations of optical axis. The numerical results show that the existence of fundamental TM{sub 0} mode and high-order TM modes in the waveguide system is dependent on the orientation of optical axis. In addition, their anomalous dispersion properties are clarified. When the orientation of optical axis is selected properly, there are two branches of dispersion curves for each high-order mode—one is normal dispersion and another belongs to anomalous dispersion, showing a transition from a backward wave to a forward one with the increase of working frequency. Moreover, the group velocity and energy flow distribution for TM{sub 1} mode are also demonstrated. These properties may have potential applications in optical information storage, integrated optics and nanophotonic devices. - Highlights: • Two kinds of subwavelength uniaxial metamaterial waveguides are constructed. • We demonstrate anomalous dispersion properties of transverse magnetic (TM) guided modes. • There are two branches of dispersion curves for high-order TM modes, showing a transition from a backward wave to a forward one. • Group velocity can approach to zero, having potential application in optical information storage. • Negative group velocity and energy flow distribution for TM modes are shown.

  12. Spin waves in terbium. III. Magnetic anisotropy at zero wave vector

    DEFF Research Database (Denmark)

    Houmann, Jens Christian Gylden; Jensen, J.; Touborg, P.

    1975-01-01

    The energy gap at zero wave vector in the spin-wave dispersion relation of ferromagnetic. Tb has been studied by inelastic neutron scattering. The energy was measured as a function of temperature and applied magnetic field, and the dynamic anisotropy parameters were deduced from the results...... the effects of zero-point deviations from the fully aligned ground state, and we tentatively propose polarization-dependent two-ion couplings as their origin........ The axial anisotropy is found to depend sensitively on the orientation of the magnetic moments in the basal plane. This behavior is shown to be a convincing indication of considerable two-ion contributions to the magnetic anisotropy at zero wave vector. With the exception of the sixfold basal...

  13. Linear and nonlinear dust ion acoustic solitary waves in a quantum dusty electron-positron-ion plasma

    Energy Technology Data Exchange (ETDEWEB)

    Emadi, E.; Zahed, H. [Physics Department, Faculty of Science, Sahand University of Technology, 51335–1996 Tabriz (Iran, Islamic Republic of)

    2016-08-15

    The behavior of linear and nonlinear dust ion acoustic (DIA) solitary waves in an unmagnetized quantum dusty plasma, including inertialess electrons and positrons, ions, and mobile negative dust grains, are studied. Reductive perturbation and Sagdeev pseudopotential methods are employed for small and large amplitude DIA solitary waves, respectively. A minimum value of the Mach number obtained for the existence of solitary waves using the analytical expression of the Sagdeev potential. It is observed that the variation on the values of the plasma parameters such as different values of Mach number M, ion to electron Fermi temperature ratio σ, and quantum diffraction parameter H can lead to the creation of compressive solitary waves.

  14. Dispersive photonic crystals from the plane wave method

    Energy Technology Data Exchange (ETDEWEB)

    Guevara-Cabrera, E.; Palomino-Ovando, M.A. [Facultad de Ciencias Físico Matemáticas, Benemérita Universidad Autónoma de Puebla, Apdo. Post. 165, Puebla, Pue. 72000, México (Mexico); Flores-Desirena, B., E-mail: bflores@fcfm.buap.mx [Facultad de Ciencias Físico Matemáticas, Benemérita Universidad Autónoma de Puebla, Apdo. Post. 165, Puebla, Pue. 72000, México (Mexico); Gaspar-Armenta, J.A. [Departamento de Investigación en Física de la Universidad de Sonora Apdo, Post 5-088, Hermosillo Sonora 83190, México (Mexico)

    2016-03-01

    Nowadays photonic crystals are widely used in many different applications. One of the most used methods to compute their band structure is the plane wave method (PWM). However, it can only be applied directly to non-dispersive media and be extended to systems with a few model dielectric functions. We explore an extension of the PWM to photonic crystals containing dispersive materials, that solves an eigenvalue equation for the Bloch wave vectors. First we compare our calculation with analytical results for one dimensional photonic crystals containing Si using experimental values of its optical parameters, and obtainig very well agreement, even for the spectrum region with strong absorption. Then, using the same method, we computed the band structure for a two dimensional photonic crystal without absorption, formed by an square array of MgO cylinders in air. The optical parameters for MgO were modeled with the Lorentz dielectric function. Finally, we studied an array of MgO cylinders in a metal, using Drude model without absorption, for the metal dielectric function. For this last case, we study the gap–midgap ratio as a function of the filling fraction for both the square and triangular lattice. The gap–midgap ratio is larger for the triangular lattice, with a maximum value of 10% for a filling fraction of 0.6. Our results show that the method can be applied to dispersive materials, and then to a wide range of applications where photonic crystals can be used.

  15. Military jet pilots have higher p-wave dispersions compared to the transport aircraft aircrew

    Directory of Open Access Journals (Sweden)

    Mustafa Çakar

    2016-08-01

    Full Text Available Objectives: For the purpose of flight safety military aircrew must be healthy. P-wave dispersion (PWD is the p-wave length difference in an electrocardiographic (ECG examination and represents the risk of developing atrial fibrillation. In the study we aimed at investigating PWD in healthy military aircrew who reported for periodical examinations. Material and Methods: Seventy-five asymptomatic military aircrew were enrolled in the study. All the subjects underwent physical, radiologic and biochemical examinations, and a 12-lead electrocardiography. P-wave dispersions were calculated. Results: The mean age of the study participants was 36.15±8.97 years and the mean p-wave duration was 100.8±12 ms in the whole group. Forty-seven subjects were non-pilot aircrew, and 28 were pilots. Thirteen study subjects were serving in jets, 49 in helicopters, and 13 were transport aircraft pilots. Thirty-six of the helicopter and 11 of the transport aircraft aircrew were non-pilot aircrew. P-wave dispersion was the lowest in the transport aircraft aircrew, and the highest in jet pilots. P-wave dispersions were similar in the pilots and non-pilot aircrew. Twenty-three study subjects were overweight, 19 had thyroiditis, 26 had hepatosteatosis, 4 had hyperbilirubinemia, 2 had hypertension, and 5 had hyperlipidemia. The PWD was significantly associated with thyroid-stimulating hormone (TSH levels. Serum uric acid levels were associated with p-wave durations. Serum TSH levels were the most important predictor of PWD. Conclusions: When TSH levels were associated with PWD, uric acid levels were associated with p-wave duration in the military aircrew. The jet pilots had higher PWDs. These findings reveal that military jet pilots may have a higher risk of developing atrial fibrillation, and PWD should be recorded during periodical examinations.

  16. Negative ion sound solitary waves revisited

    Science.gov (United States)

    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.

  17. Monte-Carlo Orbit/Full Wave Simulation of Fast Alfven Wave (FW) Damping on Resonant Ions in Tokamaks

    International Nuclear Information System (INIS)

    Choi, M.; Chan, V.S.; Pinsker, R.I.; Tang, V.; Bonoli, P.; Wright, J.

    2005-01-01

    To simulate the resonant interaction of fast Alfven wave (FW) heating and Coulomb collisions on energetic ions, including finite orbit effects, a Monte-Carlo code ORBIT-RF has been coupled with a 2D full wave code TORIC4. ORBIT-RF solves Hamiltonian guiding center drift equations to follow trajectories of test ions in 2D axisymmetric numerical magnetic equilibrium under Coulomb collisions and ion cyclotron radio frequency quasi-linear heating. Monte-Carlo operators for pitch-angle scattering and drag calculate the changes of test ions in velocity and pitch angle due to Coulomb collisions. A rf-induced random walk model describing fast ion stochastic interaction with FW reproduces quasi-linear diffusion in velocity space. FW fields and its wave numbers from TORIC are passed on to ORBIT-RF to calculate perpendicular rf kicks of resonant ions valid for arbitrary cyclotron harmonics. ORBIT-RF coupled with TORIC using a single dominant toroidal and poloidal wave number has demonstrated consistency of simulations with recent DIII-D FW experimental results for interaction between injected neutral-beam ions and FW, including measured neutron enhancement and enhanced high energy tail. Comparison with C-Mod fundamental heating discharges also yielded reasonable agreement

  18. Alfven waves and associated energetic ions downstream from Uranus

    International Nuclear Information System (INIS)

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

    1991-01-01

    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 -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

  19. Lamb wave extraction of dispersion curves in micro/nano-plates using couple stress theories

    Science.gov (United States)

    Ghodrati, Behnam; Yaghootian, Amin; Ghanbar Zadeh, Afshin; Mohammad-Sedighi, Hamid

    2018-01-01

    In this paper, Lamb wave propagation in a homogeneous and isotropic non-classical micro/nano-plates is investigated. To consider the effect of material microstructure on the wave propagation, three size-dependent models namely indeterminate-, modified- and consistent couple stress theories are used to extract the dispersion equations. In the mentioned theories, a parameter called 'characteristic length' is used to consider the size of material microstructure in the governing equations. To generalize the parametric studies and examine the effect of thickness, propagation wavelength, and characteristic length on the behavior of miniature plate structures, the governing equations are nondimensionalized by defining appropriate dimensionless parameters. Then the dispersion curves for phase and group velocities are plotted in terms of a wide frequency-thickness range to study the lamb waves propagation considering microstructure effects in very high frequencies. According to the illustrated results, it was observed that the couple stress theories in the Cosserat type material predict more rigidity than the classical theory; so that in a plate with constant thickness, by increasing the thickness to characteristic length ratio, the results approach to the classical theory, and by reducing this ratio, wave propagation speed in the plate is significantly increased. In addition, it is demonstrated that for high-frequency Lamb waves, it converges to dispersive Rayleigh wave velocity.

  20. The statistical mechanics of vortex-acoustic ion wave turbulence

    International Nuclear Information System (INIS)

    Giles, M.J.

    1980-01-01

    The equilibrium statistical mechanics of electrostatic ion wave turbulence is studied within the framework of a continuum ion flow with adiabatic electrons. The wave field consists in general of two components, namely ion-acoustic and ion vortex modes. It is shown that the latter can significantly affect the equilibria on account of their ability both to emit and to scatter ion sound. Exact equilibria for the vortex-acoustic wave field are given in terms of a canonical distribution and the correlation functions are expressed in terms of a generating functional. Detailed calculations are carried out for the case in which the dominant coupling is an indirect interaction of the vortex modes mediated by the sound field. An equation for the spectrum of the vortex modes is obtained for this case, which is shown to possess a simple exact solution. This solution shows that the spectrum of fluctuations changes considerably as the total energy increases. Condensed vortex states could occur in the plasma sheet of the earth's magnetosphere and it is shown that the predicted ratio of the mean ion energy to the mean electron energy is consistent with the trend of observed values. (author)

  1. Effects of Heavy Ions on ULF Wave Resonances Near the Equatorial Region

    International Nuclear Information System (INIS)

    Lee, D.-H.; Johnson, J.R.; Kim, K.; Kim, K.-S.

    2008-01-01

    Pc1-2 ULF waves are strongly associated with the presence of various ions in the magnetosphere. We investigate the role of heavy ion resonances in nonuniform plasmas near the equatorial region. By adopting the invariant imbedding method, the coupled plasma wave equations are solved in an exact manner to calculate the resonant absorption at the ion-ion hybrid resonance. Our results show that irreversible mode conversion occurs at the resonance, which absorbs the fast wave energy. It is found that waves near the resonances appear with linear polarization, and their amplitude and frequency are sensitive to the properties of the heavy ion plasma composition. We examine how these resonances occur for various H+ - He+ populations in detail by performing an accurate calculation of the mode conversion efficiency. Because the multi-ion hybrid resonance locations in cold plasmas are determined by simple parameters such as the fraction of the ion number density of each species and the magnetic field, we suggest that it is possible to monitor heavy ion composition by examining the peak frequencies of linearly polarized wave events in either electric field or magnetic field spectral data

  2. Effects of Heavy Ions on ULF Wave Resonances Near the Equatorial Region

    Energy Technology Data Exchange (ETDEWEB)

    D.-H.Lee, J.R. Johnson, K. Kim and K.-S.Kim

    2008-11-20

    Pc1-2 ULF waves are strongly associated with the presence of various ions in the magnetosphere. We investigate the role of heavy ion resonances in nonuniform plasmas near the equatorial region. By adopting the invariant imbedding method, the coupled plasma wave equations are solved in an exact manner to calculate the resonant absorption at the ion-ion hybrid resonance. Our results show that irreversible mode conversion occurs at the resonance, which absorbs the fast wave energy. It is found that waves near the resonances appear with linear polarization, and their amplitude and frequency are sensitive to the properties of the heavy ion plasma composition. We examine how these resonances occur for various H+ - He+ populations in detail by performing an accurate calculation of the mode conversion effciency. Because the multi-ion hybrid resonance locations in cold plasmas are determined by simple parameters such as the fraction of the ion number density of each species and the magnetic field, we suggest that it is possible to monitor heavy ion composition by examining the peak frequencies of linearly polarized wave events in either electric field or magnetic field spectral data.

  3. Wave Telescope Technique for MMS Magnetometer

    Science.gov (United States)

    Narita, Y.; Plaschke, F.; Nakamura, R.; Baumjojann, W.; Magnes, W.; Fischer, D.; Voros, Z.; Torbert, R. B.; Russell, C. T.; Strangeway, R. J.; hide

    2016-01-01

    Multipoint measurements are a powerful method in studying wavefields in space plasmas.The wave telescope technique is tested against magnetic field fluctuations in the terrestrial magnetosheath measured by the four Magnetospheric Multiscale (MMS) spacecraft on a spatial scale of about 20 km.The dispersion relation diagram and the wave vector distribution are determined for the first time in the ion-kinetic range. Moreover, the dispersion relation diagram is determined in a proxy plasma restframe by regarding the low-frequency dispersion relation as a Doppler relation and compensating for the apparent phase velocity. Fluctuations are highly compressible, and the wave vectors have an angle of about 60 from the mean magnetic field. We interpret that the measured fluctuations represent akinetic-drift mirror mode in the magnetosheath which is dispersive and in a turbulent state accompanied by a sideband formation.

  4. Compact dispersion relations for parametric instabilities of electromagnetic waves in magnetized plasmas

    International Nuclear Information System (INIS)

    Cohen, B.I.

    1987-01-01

    The existence of compact dispersion relations for parametric instabilities of coherent electromagnetic waves in magnetized plasmas is addressed here. In general, comprehensive dispersion relations for parametric instabilities in unmagnetized plasmas become more complicated in the presence of an applied time-independent magnetic field. This is demonstrated with a fluid perturbation theory. A compact dispersion relation for parametric instabilities in unmagnetized plasma is heuristically extended here to the case of a magnetized plasma. This dispersion relation gives the correct results in a variety of circumstances of interest in considering electron cyclotron heating applications

  5. Physics of the ion acoustic wave driven by the stimulated Brillouin scattering instability

    International Nuclear Information System (INIS)

    Clayton, C.E.

    1984-01-01

    The ion acoustic wave excited in the stimulated Brillouin scattering (SBS) instability is probed via collective ruby-laser Thomson scattering in order to understand the low saturation level observed in the instability. Many of the features observed in the Brillouin backscattered CO 2 laser light from the underdense gas-target plasma are also observed in the Thomson scattered ruby light - from which it is learned that the ion acoustic wave grows exponentially and then saturates as the CO 2 pump power is increased. The primary advantage of the ruby Thomson scattering diagnostic is in its capability of providing simultaneous space and time resolved measurements of the ion wave amplitude. From these first such detailed measurements, it was found that the ion wave grows exponentially in space at a rate that agrees with the linear convective SBS theory. However, at higher pump powers, the ion wave saturates at an inferred amplitude of anti-n/n 0 approx. = 5 to 10%. Further increases in the pump power appear to result in an increase in the length over which the ion wave is saturated. A nearly constant SBS reflectivity in this saturated regime, however, suggests that the saturated ion wave does not contribute as much to the scattered power as would be expected from Bragg scattering theory. This apparent contradiction can be resolved if ion trapping is responsible for the saturation of the ion wave

  6. Mechanisms of elastic wave generation in solids by ion impact

    International Nuclear Information System (INIS)

    Deemer, B.; Murphy, J.; Claytor, T.

    1990-01-01

    This study is directed at understanding the mechanisms of acoustic signal generation by modulated beams of energetic ions as a function of ion energy. Interaction of ions with solids initiates a range of processes including sputtering, ion implantation, ionization, both internal and external, as well as thermal deposition in the solid. Accumulated internal stress also occurs by generation of dislocations resulting from, inelastic nuclear scattering of the incident ion beam. With respect to elastic wave generation, two potential mechanisms are thermoelastic induced stress and momentum transfer. The latter process includes contributions of momentum transfer from the incident beam and from ions ejected via sputtering. Other aspects of the generation process include the potential for shock wave generation since the mean particle velocity for a wide range of ion energies exceeds the velocity of sound in solids. This study seeks to distinguish the contribution of these mechanisms by studying the signature, angular distribution and energy dependence of the elastic wave response in the time domain and to use this information to understand technologically important processes such as implantation and sputtering

  7. The Effects of Hydrogen Band EMIC Waves on Ring Current H+ Ions

    Science.gov (United States)

    Wang, Zhiqiang; Zhai, Hao; Gao, Zhuxiu

    2017-12-01

    Hydrogen band electromagnetic ion cyclotron (EMIC) waves have received much attention recently because they are found to frequently span larger spatial areas than the other band EMIC waves. Using test particle simulations, we study the nonlinear effects of hydrogen band EMIC waves on ring current H+ ions. A dimensionless parameter R is used to characterize the competition between wave-induced and adiabatic motions. The results indicate that there are three regimes of wave-particle interactions for typical 35 keV H+ ions at L = 5: diffusive (quasi-linear) behavior when αeq ≤ 35° (R ≥ 2.45), the nonlinear phase trapping when 35° < αeq < 50° (0.75 < R < 2.45), and both the nonlinear phase bunching and phase trapping when αeq ≥ 50° (R ≤ 0.75). The phase trapping can transport H+ ions toward large pitch angle, while the phase bunching has the opposite effect. The phase-trapped H+ ions can be significantly accelerated (from 35 keV to over 500 keV) in about 4 min and thus contribute to the formation of high energy components of ring current ions. The results suggest that the effect of hydrogen band EMIC waves is not ignorable in the nonlinear acceleration and resonance scattering of ring current H+ ions.

  8. Observation of fast-ion Doppler-shifted cyclotron resonance with shear Alfven waves

    International Nuclear Information System (INIS)

    Zhang Yang; Heidbrink, W. W.; Boehmer, H.; McWilliams, R.; Vincena, S.; Carter, T. A.; Gekelman, W.; Leneman, D.; Pribyl, P.

    2008-01-01

    The Doppler-shifted cyclotron resonance (ω-k z v z =Ω f ) between fast ions and shear Alfven waves is experimentally investigated (ω, wave frequency; k z , axial wavenumber; v z , fast-ion axial speed; Ω f , fast-ion cyclotron frequency). A test particle beam of fast ions is launched by a Li + 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 δ 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 0.3-0.8ω 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.

  9. 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

    Science.gov (United States)

    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 approximately 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 eld 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.

  10. Dispersive Wave Analysis Using the Chirplet Transform

    International Nuclear Information System (INIS)

    Kerber, Florian; Luangvilai, Kritsakorn; Kuttig, Helge; Niethammer, Marc; Jacobs, Laurence J.

    2007-01-01

    Time-frequency representations (TFR) are a widely used tool to analyze signals of guided waves such as Lamb waves. As a consequence of the uncertainty principle, however, the resolution in time and frequency is limited for all existing TFR methods. Due to the multi-modal and dispersive character of Lamb waves, displacement or energy related quantities can only be allocated to individual modes when they are well-separated in the time-frequency plane.The chirplet transform (CT) has been introduced as a generalization of both the wavelet and Short-time Fourier transform (STFT). It offers additional degrees of freedom to adjust time-frequency atoms which can be exploited in a model-based approach to match the group delay of individual modes. Thus, more exact allocation of quantities of interest is possible.The objective of this research is to use a previously developed adaptive algorithm based on the CT for nondestructive evaluation. Both numerically and experimentally generated data for a single aluminum plate is analyzed to determine the accuracy and robustness of the new method in comparison the classical STFT

  11. Ion acoustic waves and related plasma observations in the solar wind

    International Nuclear Information System (INIS)

    Gurnett, D.A.; Marsch, E.; Pilipp, W.; Schwenn, R.; Rosenbauer, H.

    1979-01-01

    This paper presents an investigation of solar wind ion acoustic waves and their relationship to the macroscopic and microscopic characteristics of the solar wind plasma. Comparisons with the overall solar wind corotational structure show that the most intense ion acoustic waves usually occur in the low-velocity regions ahead of high-speed solar wind streams. Of the detailed plasma parameters investigated, the ion acoustic wave intensities are found to be most closely correlated with the electron to proton temperature ratio T/sub e//T/sub p/ and with the electron heat flux. Investigations of the detailed electron and proton distribution functions also show that the ion acoustic waves usually occur in regions with highly non-Maxwellian distributions characteristic of double-proton streams. The distribution functions for the double-proton streams are usually not resolved into two clearly defined peaks, but rather they appear as a broad shoulder on the main proton distribution. Two main mechanisms, an electron heat flux instability and a double-ion beam instability, are considered for generating the ion-acoustic-like waves observed in the solar wind. Both mechanisms have favorable and unfavorable features. The electron heat flux mechanism can account for the observed waves at moderate to large ratios of T/sub e//T/sub p/ but has problems when T/sub e//T/sub p/ is small, as sometimes occurs. The ion beam instability appears to provide more flexibility on the T/sub e//T/sub p/ ratio; however detailed comparisons using observed distribution functions indicate that the ion beam mode is usually stable. Possible resolutions of these difficulties are discussed

  12. Amplification of electromagnetic ion cyclotron waves along a wave path in the Earth's multicomponent magnetosphere

    International Nuclear Information System (INIS)

    Hu, Y.D.; Fraser, B.J.; Olson, J.V.

    1990-01-01

    In this report, the authors consider the amplification of electromagnetic ion cyclotron waves along a geomagnetic field line in the multicomponent magnetosphere, assuming that the waves propagate parallel to the background magnetic field. The find it is possible for the ring-current protons (energy ∼ 10-100 keV), which supply the free energy to stimulate the waves, to resonate with the waves not only in the equatorial region but also off the equator. An instability, caused by a thermal anisotropy, may occur in separated regions on and/or off the equator. The positions of the source regions along the wave path depend on the concentration of cold heavy ion species. The significant off-equator source regions may be located at geomagnetic latitudes where the waves, with frequencies greater than the He + gyrofrequency on the equator, are in a local He + pass band

  13. Stimulated ion Compton scattering instability of whistlers in plasmas

    International Nuclear Information System (INIS)

    Shukla, P. K.; Shukla, Nitin; Stenflo, L.

    2006-01-01

    The nonlinear interactions between magnetic field-aligned broadband whistler wave packets (hereafter referred to as whistlerons) and ion quasimodes in magnetized plasmas are considered. By treating the whistlerons as quasiparticles, their nonlinear propagation in a slowly varying medium supported by ion quasimode density perturbations is studied. A nonlinear dispersion relation within the framework of the wave-kinetic (for the whistlerons) and Vlasov (for the ion quasimodes) descriptions is derived. The dispersion relation admits a kinetic modulational instability. The growth rate of the latter is presented. The present result can improve our understanding of the nonlinear propagation of incoherent whistlers, which have been frequently observed in the Earth's magnetosphere as well as in laboratory plasmas

  14. Energy Properties of Ion Acoustic Waves in Stable and Unstable Plasmas

    DEFF Research Database (Denmark)

    Jensen, Vagn Orla; Lynov, Jens-Peter

    1979-01-01

    Energy exchange between potential energy and ion kinetic energy in an ion acoustic wave is considered. In order to investigate the linear Landau damping or growth, the energy is calculated by use of first‐order quantities only so that nonlinear effects are not involved. It is found that for ion...... acoustic waves that are growing or damped in space the time average of the sum of the potential and the kinetic energy density is independent of position. Energy absorption spectra in particle velocity space are calculated; they are relatively broad and complicated functions. This shows that plasma ions...... of all velocities exchange energy with the wave....

  15. ION HEATING IN INHOMOGENEOUS EXPANDING SOLAR WIND PLASMA: THE ROLE OF PARALLEL AND OBLIQUE ION-CYCLOTRON WAVES

    International Nuclear Information System (INIS)

    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

  16. Effect of ion suprathermality on arbitrary amplitude dust acoustic waves in a charge varying dusty plasma

    International Nuclear Information System (INIS)

    Tribeche, Mouloud; Mayout, Saliha; Amour, Rabia

    2009-01-01

    Arbitrary amplitude dust acoustic waves in a high energy-tail ion distribution are investigated. The effects of charge variation and ion suprathermality on the large amplitude dust acoustic (DA) soliton are then considered. The correct suprathermal ion charging current is rederived based on the orbit motion limited approach. In the adiabatic case, the variable dust charge is expressed in terms of the Lambert function and we take advantage of this transcendental function to show the existence of rarefactive variable charge DA solitons involving cusped density humps. The dust charge variation leads to an additional enlargement of the DA soliton, which is less pronounced as the ions evolve far away from Maxwell-Boltzmann distribution. In the nonadiabatic case, the dust charge fluctuation may provide an alternate physical mechanism causing anomalous dissipation the strength of which becomes important and may prevail over that of dispersion as the ion spectral index κ increases. Our results may provide an explanation for the strong spiky waveforms observed in auroral electric field measurements by Ergun et al.[Geophys. Res. Lett. 25, 2025 (1998)].

  17. Collisionless damping of nonlinear dust ion acoustic wave due to dust charge fluctuation

    International Nuclear Information System (INIS)

    Ghosh, Samiran; Chaudhuri, Tushar K.; Sarkar, Susmita; Khan, Manoranjan; Gupta, M.R.

    2002-01-01

    A dissipation mechanism for the damping of the nonlinear dust ion acoustic wave in a collisionless dusty plasma consisting of nonthermal electrons, ions, and variable charge dust grains has been investigated. It is shown that the collisionless damping due to dust charge fluctuation causes the nonlinear dust ion acoustic wave propagation to be described by the damped Korteweg-de Vries equation. Due to the presence of nonthermal electrons, the dust ion acoustic wave admits both positive and negative potential and it suffers less damping than the dust acoustic wave, which admits only negative potential

  18. Defocusing regimes of nonlinear waves in media with negative dispersion

    DEFF Research Database (Denmark)

    Bergé, L.; Kuznetsov, E.A.; Juul Rasmussen, J.

    1996-01-01

    Defocusing regimes of quasimonochromatic waves governed by a nonlinear Schrodinger equation with mixed-sign dispersion are investigated. For a power-law nonlinearity, we show that localized solutions to this equation defined at the so-called critical dimension cannot collapse in finite time...

  19. Solitons and nonlinear waves in space plasmas

    International Nuclear Information System (INIS)

    Stasiewicz, K.

    2005-01-01

    Recent measurements made on the ESA/NASA Cluster mission to the Earth's magnetosphere have provided first detailed measurements of magnetosonic solitons in space. The solitons represent localized enhancements of the magnetic field by a factor of 2-10, or depressions down to 10% of the ambient field. The magnetic field signatures are associated with density depressions/enhancements A two-fluid model of nonlinear electron and ion inertial waves in anisotropic plasmas explains the main properties of these structures. It is shown that warm plasmas support four types of nonlinear waves, which correspond to four linear modes: Alfvenic, magnetosonic, sound, and electron inertial waves. Each of these nonlinear modes has slow and fast versions. It is shown by direct integration that the exponential growth rate of nonlinear modes is balanced by the ion and electron dispersion leading to solutions in the form of trains of solitons or cnoidal waves. By using a novel technique of phase portraits it is shown how the dispersive properties of electron and ion inertial waves change at the transition between warm and hot plasmas, and how trains of solitons ('' mirror modes '') are produced in a hot, anisotropic plasma. The applicability of the model is illustrated with data from Cluster spacecraft. (author)

  20. Ion-acoustic solitary waves near double layers

    International Nuclear Information System (INIS)

    Kuehl, H.H.; Imen, K.

    1985-01-01

    The possibility of ion-acoustic solitary-wave solutions in the uniform plasma on the high-potential side of double layer is investigated. Based on a fluid model of the double layer, it is found that both compressive and rarefactive solitary waves are allowed. Curves are presented which show the regions in parameter space in which these solutions exist

  1. Large amplitude ion-acoustic waves in a plasma with an electron beam

    International Nuclear Information System (INIS)

    Nejoh, Y.; Sanuki, H.

    1995-01-01

    The nonlinear wave structures of large amplitude ion-acoustic waves are studied in a plasma with an electron beam, by the pseudopotential method. The region of the existence of large amplitude ion-acoustic waves is examined, showing that the condition of the existence sensitively depends on the parameters such as the electron beam temperature, the ion temperature, the electrostatic potential, and the concentration of the electron beam density. It turns out that the region of the existence spreads as the beam temperature increases but the effect of the electron beam velocity is relatively small. New findings of large amplitude ion-acoustic waves in a plasma with an electron beam are predicted. copyright 1995 American Institute of Physics

  2. Full-wave modeling of ICRF waves: global and quasi-local descriptions

    International Nuclear Information System (INIS)

    Dumont, R. J.

    2007-01-01

    Waves in the Ion Cyclotron Range of Frequencies (ICRF) undergo significant space dispersion as they propagate in magnetic fusion plasmas, making it necessary to incorporate non-local effects in their physical description. Full-wave codes are routinely employed to simulate ICRF heating experiments in tokamaks. The vast majority of these codes rely on a description of the plasma based on a 'quasi-local' derivation of the dielectric tensor, i.e. assuming that the range of space dispersion remains small compared to the system dimensions. However, non-local effects caused by wide particle orbits are expected to play a significant role in current and future experiments featuring wave-driven fast ions, fusion-born alpha particles... Global formalisms have thus been proposed to include these effects in a more comprehensive fashion. Based on a description of the particle dynamics in terms of action-angle variables, a full-wave code, named EVE, is currently under development. Its first version, presented here, incorporates quasi-local expressions valid to second order in Larmor radius, derived from the more general Hamiltonian formalism. The obtained tool has the advantage of being compatible with the current requirements of integrated modeling, and lends itself to direct comparisons with existing codes

  3. Identification of low-frequency kinetic wave modes in the Earth's ion foreshock

    Directory of Open Access Journals (Sweden)

    X. Blanco-Cano

    1997-03-01

    Full Text Available In this work we use ion and magnetic field data from the AMPTE-UKS mission to study the characteristics of low frequency (ωr « Ωp waves observed upstream of the Earth's bow shock. We test the application of various plasma-field correlations and magnetic ratios derived from linear Vlasov theory to identify the modes in this region. We evaluate (for a parameter space consistent with the ion foreshock the Alfvén ratio, the parallel compressibility, the cross-helicity, the noncoplanar ratio, the magnetic compression and the polarization for the two kinetic instabilities that can be generated in the foreshock by the interaction of hot diffuse ions with the solar wind: the left-hand resonant and the right-hand resonant ion beam instabilities. Comparison of these quantities with the observed plasma-field correlations and various magnetic properties of the waves observed during 10 intervals on 30 October 1984, where the waves are associated with diffuse ions, allows us to identify regions with Alfvénic waves and regions where the predominant mode is the right-hand resonant instability. In all the cases the waves are transverse, propagating at angles ≤ 33° and are elliptically polarized. Our results suggest that while the observed Alfvén waves are generated locally by hot diffuse ions, the right-handed waves may result from the superposition of waves generated by two different types of beam distribution (i.e. cold beam and diffuse ions. Even when there was good agreement between the values of observed transport ratios and the values given by the theory, some discrepancies were found. This shows that the observed waves are different from the theoretical modes and that mode identification based only on polarization quantities does not give a complete picture of the waves' characteristics and can lead to mode identification of waves whose polarization may agree with theoretical predictions even when other properties can diverge from those of the

  4. Databases of surface wave dispersion

    Directory of Open Access Journals (Sweden)

    L. Boschi

    2005-06-01

    Full Text Available Observations of seismic surface waves provide the most important constraint on the elastic properties of the Earth’s lithosphere and upper mantle. Two databases of fundamental mode surface wave dispersion were recently compiled and published by groups at Harvard (Ekström et al., 1997 and Utrecht/Oxford (Trampert and Woodhouse, 1995, 2001, and later employed in 3-d global tomographic studies. Although based on similar sets of seismic records, the two databases show some significant discrepancies. We derive phase velocity maps from both, and compare them to quantify the discrepancies and assess the relative quality of the data; in this endeavour, we take careful account of the effects of regularization and parametrization. At short periods, where Love waves are mostly sensitive to crustal structure and thickness, we refer our comparison to a map of the Earth’s crust derived from independent data. On the assumption that second-order effects like seismic anisotropy and scattering can be neglected, we find the measurements of Ekström et al. (1997 of better quality; those of Trampert and Woodhouse (2001 result in phase velocity maps of much higher spatial frequency and, accordingly, more difficult to explain and justify geophysically. The discrepancy is partly explained by the more conservative a priori selection of data implemented by Ekström et al. (1997. Nevertheless, it becomes more significant with decreasing period, which indicates that it could also be traced to the different measurement techniques employed by the authors.

  5. Imaging ultrasonic dispersive guided wave energy in long bones using linear radon transform.

    Science.gov (United States)

    Tran, Tho N H T; Nguyen, Kim-Cuong T; Sacchi, Mauricio D; Le, Lawrence H

    2014-11-01

    Multichannel analysis of dispersive ultrasonic energy requires a reliable mapping of the data from the time-distance (t-x) domain to the frequency-wavenumber (f-k) or frequency-phase velocity (f-c) domain. The mapping is usually performed with the classic 2-D Fourier transform (FT) with a subsequent substitution and interpolation via c = 2πf/k. The extracted dispersion trajectories of the guided modes lack the resolution in the transformed plane to discriminate wave modes. The resolving power associated with the FT is closely linked to the aperture of the recorded data. Here, we present a linear Radon transform (RT) to image the dispersive energies of the recorded ultrasound wave fields. The RT is posed as an inverse problem, which allows implementation of the regularization strategy to enhance the focusing power. We choose a Cauchy regularization for the high-resolution RT. Three forms of Radon transform: adjoint, damped least-squares, and high-resolution are described, and are compared with respect to robustness using simulated and cervine bone data. The RT also depends on the data aperture, but not as severely as does the FT. With the RT, the resolution of the dispersion panel could be improved up to around 300% over that of the FT. Among the Radon solutions, the high-resolution RT delineated the guided wave energy with much better imaging resolution (at least 110%) than the other two forms. The Radon operator can also accommodate unevenly spaced records. The results of the study suggest that the high-resolution RT is a valuable imaging tool to extract dispersive guided wave energies under limited aperture. Copyright © 2014 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

  6. Observation of Self-Cavitating Envelope Dispersive Shock Waves in Yttrium Iron Garnet Thin Films

    Science.gov (United States)

    Janantha, P. A. Praveen; Sprenger, Patrick; Hoefer, Mark A.; Wu, Mingzhong

    2017-07-01

    The formation and properties of envelope dispersive shock wave (DSW) excitations from repulsive nonlinear waves in a magnetic film are studied. Experiments involve the excitation of a spin wave step pulse in a low-loss magnetic Y3Fe5O12 thin film strip, in which the spin wave amplitude increases rapidly, realizing the canonical Riemann problem of shock theory. Under certain conditions, the envelope of the spin wave pulse evolves into a DSW that consists of an expanding train of nonlinear oscillations with amplitudes increasing from front to back, terminated by a black soliton. The onset of DSW self-cavitation, indicated by a point of zero power and a concomitant 180° phase jump, is observed for sufficiently large steps, indicative of the bidirectional dispersive hydrodynamic nature of the DSW. The experimental observations are interpreted with theory and simulations of the nonlinear Schrödinger equation.

  7. Solitary waves for a coupled nonlinear Schrodinger system with dispersion management

    Directory of Open Access Journals (Sweden)

    Panayotis Panayotaros

    2010-08-01

    Full Text Available We consider a system of coupled nonlinear Schrodinger equations with periodically varying dispersion coefficient that arises in the context of fiber-optics communication. We use Lions's Concentration Compactness principle to show the existence of standing waves with prescribed L^2 norm in an averaged equation that approximates the coupled system. We also use the Mountain Pass Lemma to prove the existence of standing waves with prescribed frequencies.

  8. Stimulated scattering of space-charge waves in a relativistic electron beam by the ion acoustic wave of a plasma waveguide

    International Nuclear Information System (INIS)

    Balakirev, V.A.; Buts, V.A.

    1982-01-01

    The interaction of a relativistic electron beam with a plasma waveguide whose density is modulated by an ion acoustic wave leads to the emission of electromagnetic radiation. The wavelength of the radiation is 2#betta# 2 times shorter than the ion acoustic wavelength. The emission is accompanied by the amplification of the ion acoustic wave. The maximum amplitudes of the excited waves are found

  9. Excitation of an ion-acoustic wave by two whistlers in a collisionless magnetoplasma

    International Nuclear Information System (INIS)

    Sodha, M.S.; Singh, T.; Singh, D.P.; Sharma, R.P.

    1981-01-01

    An investigation is made into the excitation of an ion-acoustic wave in a collisionless hot magnetoplasma by two whistlers. On account of the interaction of the two whistlers, of frequencies ω 1 and ω 2 , ponderomotive force at frequency Δω(=ω 1 -ω 2 ) leads to the generation of an ion-acoustic wave. When the two whistlers have initially Gaussian intensity distributions, a d.c. component of the ponderomotive force leads to the redistribution of the background electron/ion density, and cross-focusing of the whistlers occurs. The power of the generated ion-acoustic wave, being dependent on the background ion density and powers of the whistlers, is further modified. The ion-acoustic wave power also changes drastically with the strength of the static magnetic field. (author)

  10. Drift wave dispersion relation for arbitrarily collisional plasma

    International Nuclear Information System (INIS)

    Angus, Justin R.; Krasheninnikov, Sergei I.

    2012-01-01

    The standard local linear analysis of drift waves in a plasma slab is generalized to be valid for arbitrarily collisional electrons by considering the electrons to be governed by the drift-kinetic equation with a BGK-like (Bhatnagar-Gross-Krook) collision operator. The obtained dispersion relation reduces to that found from collisionless kinetic theory when the collision frequency is zero. Electron temperature fluctuations must be retained in the standard fluid analysis in order to obtain good quantitative agreement with our general solution in the highly collisional limit. Any discrepancies between the fluid solution and our general solution in this limit are attributed to the limitations of the BGK collision operator. The maximum growth rates in both the collisional and collisionless limits are comparable and are both on the order of the fundamental drift wave frequency. The main role of the destabilizing mechanism is found to be in determining the parallel wave number at which the maximum growth rate will occur. The parallel wave number corresponding to the maximum growth rate is set by the wave-particle resonance condition in the collisionless limit and transitions to being set by the real frequency being on the order of the rate for electrons to diffuse a parallel wavelength in the collisional limit.

  11. Drift wave dispersion relation for arbitrarily collisional plasma

    Energy Technology Data Exchange (ETDEWEB)

    Angus, Justin R.; Krasheninnikov, Sergei I. [Department of Mechanical and Aerospace Engineering, University of California, San Diego, La Jolla, California 92093-0417 (United States)

    2012-05-15

    The standard local linear analysis of drift waves in a plasma slab is generalized to be valid for arbitrarily collisional electrons by considering the electrons to be governed by the drift-kinetic equation with a BGK-like (Bhatnagar-Gross-Krook) collision operator. The obtained dispersion relation reduces to that found from collisionless kinetic theory when the collision frequency is zero. Electron temperature fluctuations must be retained in the standard fluid analysis in order to obtain good quantitative agreement with our general solution in the highly collisional limit. Any discrepancies between the fluid solution and our general solution in this limit are attributed to the limitations of the BGK collision operator. The maximum growth rates in both the collisional and collisionless limits are comparable and are both on the order of the fundamental drift wave frequency. The main role of the destabilizing mechanism is found to be in determining the parallel wave number at which the maximum growth rate will occur. The parallel wave number corresponding to the maximum growth rate is set by the wave-particle resonance condition in the collisionless limit and transitions to being set by the real frequency being on the order of the rate for electrons to diffuse a parallel wavelength in the collisional limit.

  12. Wave dispersion characteristics of axially loaded magneto-electro-elastic nanobeams

    Science.gov (United States)

    Ebrahimi, Farzad; Barati, Mohammad Reza; Dabbagh, Ali

    2016-11-01

    The analysis of wave propagation behavior of a magneto-electro-elastic functionally graded (MEE-FG) nanobeam is performed in the framework of classical beam theory. To capture small-scale effects, the nonlocal elasticity theory of Eringen is applied. Furthermore, the material properties of nanobeam are assumed to vary gradually through the thickness based on power-law form. Nonlocal governing equations of MEE-FG nanobeam have been derived employing Hamilton's principle. The results of present research have been validated by comparing with those of previous investigations. An analytical solution of governing equations is utilized to obtain wave frequencies, phase velocities and escape frequencies. Effects of various parameters such as wave number, nonlocal parameter, gradient index, axial load, magnetic potential and electric voltage on wave dispersion characteristics of MEE-FG nanoscale beams are studied in detail.

  13. Soliton shock wave fronts and self-similar discontinuities in dispersion hydrodynamics

    International Nuclear Information System (INIS)

    Gurevich, A.V.; Meshcherkin, A.P.

    1987-01-01

    Nonlinear flows in nondissipative dispersion hydrodynamics are examined. It is demonstrated that in order to describe such flows it is necessary to incorporate a new concept: a special discontinuity called a ''self-similar'' discontinuity consisting of a nondissipative shock wave and a powerful slow wave discontinuity in regular hydrodynamics. The ''self similar discontinuity'' expands linearly over time. It is demonstrated that this concept may be introduced in a solution to Euler equations. The boundary conditions of the ''self similar discontinuity'' that allow closure of Euler equations for dispersion hydrodynamics are formulated, i.e., those that replace the shock adiabatic curve of standard dissipative hydrodynamics. The structure of the soliton front and of the trailing edge of the shock wave is investigated. A classification and complete solution are given to the problem of the decay of random initial discontinuities in the hydrodynamics of highly nonisothermic plasma. A solution is derived to the problem of the decay of initial discontinuities in the hydrodynamics of magnetized plasma. It is demonstrated that in this plasma, a feature of current density arises at the point of soliton inversion

  14. On the propagation of truncated localized waves in dispersive silica

    KAUST Repository

    Salem, Mohamed

    2010-01-01

    Propagation characteristics of truncated Localized Waves propagating in dispersive silica and free space are numerically analyzed. It is shown that those characteristics are affected by the changes in the relation between the transverse spatial spectral components and the wave vector. Numerical experiments demonstrate that as the non-linearity of this relation gets stronger, the pulses propagating in silica become more immune to decay and distortion whereas the pulses propagating in free-space suffer from early decay and distortion. © 2010 Optical Society of America.

  15. Unstructured Spectral Element Model for Dispersive and Nonlinear Wave Propagation

    DEFF Research Database (Denmark)

    Engsig-Karup, Allan Peter; Eskilsson, Claes; Bigoni, Daniele

    2016-01-01

    We introduce a new stabilized high-order and unstructured numerical model for modeling fully nonlinear and dispersive water waves. The model is based on a nodal spectral element method of arbitrary order in space and a -transformed formulation due to Cai, Langtangen, Nielsen and Tveito (1998). In...

  16. Smooth and non-smooth travelling waves in a nonlinearly dispersive Boussinesq equation

    International Nuclear Information System (INIS)

    Shen Jianwei; Xu Wei; Lei Youming

    2005-01-01

    The dynamical behavior and special exact solutions of nonlinear dispersive Boussinesq equation (B(m,n) equation), u tt -u xx -a(u n ) xx +b(u m ) xxxx =0, is studied by using bifurcation theory of dynamical system. As a result, all possible phase portraits in the parametric space for the travelling wave system, solitary wave, kink and anti-kink wave solutions and uncountably infinite many smooth and non-smooth periodic wave solutions are obtained. It can be shown that the existence of singular straight line in the travelling wave system is the reason why smooth waves converge to cusp waves, finally. When parameter are varied, under different parametric conditions, various sufficient conditions guarantee the existence of the above solutions are given

  17. Localization of Ultra-Low Frequency Waves in Multi-Ion Plasmas of the Planetary Magnetosphere

    Directory of Open Access Journals (Sweden)

    Eun-Hwa Kim

    2015-12-01

    Full Text Available 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. 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.

  18. Hybrid dispersive media with controllable wave propagation: A new take on smart materials

    Energy Technology Data Exchange (ETDEWEB)

    Bergamini, Andrea E., E-mail: andrea.bergamini@empa.ch [Empa, Materials Science and Technology, Laboratory for Mechanical Integrity of Energy Systems, Überlandstrasse 129, CH-8600, Dübendorf (Switzerland); Zündel, Manuel [ETH Zürich, Institute of Mechanical Systems, Leonhardstrasse 21, CH-8092 Zürich (Switzerland); Flores Parra, Edgar A.; Ermanni, Paolo [ETH Zürich, Composite Materials and Adaptive Structures Laboratory, Leonhardstrasse 21, CH-8092 Zürich (Switzerland); Delpero, Tommaso [Empa, Materials Science and Technology, Laboratory for Mechanical Integrity of Energy Systems, Überlandstrasse 129, CH-8600 Dübendorf (Switzerland); Ruzzene, Massimo [Georgia Institute of Technology, G.W. Woodruff School of Mechanical Engineering, 801 Ferst Drive, Atlanta, Georgia 30332-0405 (United States)

    2015-10-21

    In this paper, we report on the wave transmission characteristics of a hybrid one dimensional (1D) medium. The hybrid characteristic is the result of the coupling between a 1D mechanical waveguide in the form of an elastic beam, supporting the propagation of transverse waves and a discrete electrical transmission line, consisting of a series of inductors connected to ground through capacitors. The capacitors correspond to a periodic array of piezoelectric patches that are bonded to the beam and that couple the two waveguides. The coupling leads to a hybrid medium that is characterized by a coincidence condition for the frequency/wavenumber value corresponding to the intersection of the branches of the two waveguides. In the frequency range centered at coincidence, the hybrid medium features strong attenuation of wave motion as a result of the energy transfer towards the electrical transmission line. This energy transfer, and the ensuing attenuation of wave motion, is alike the one obtained through internal resonating units of the kind commonly used in metamaterials. However, the distinct shape of the dispersion curves suggests how this energy transfer is not the result of a resonance and is therefore fundamentally different. This paper presents the numerical investigation of the wave propagation in the considered media, it illustrates experimental evidence of wave transmission characteristics and compares the performance of the considered configuration with that of internal resonating metamaterials. In addition, the ability to conveniently tune the dispersion properties of the electrical transmission line is exploited to adapt the periodicity of the domain and to investigate diatomic periodic configurations that are characterized by a richer dispersion spectrum and broader bandwidth of wave attenuation at coincidence. The medium consisting of mechanical, piezoelectric, and analog electronic elements can be easily interfaced to digital devices to offer a novel

  19. Large amplitude ion-acoustic solitary waves and double layers in multicomponent plasma with positrons

    International Nuclear Information System (INIS)

    Sabry, R.

    2009-01-01

    A finite amplitude theory for ion-acoustic solitary waves and double layers in multicomponent plasma consisting of hot positrons, cold ions, and electrons with two-electron temperature distributions is presented. Conditions are obtained under which large amplitude stationary ion-acoustic solitary waves and double layers can exist. For the physical parameters of interest, the ion-acoustic solitary wave (double layers) profiles and the relationship between the maximum soliton (double layers) amplitude and the Mach number are found. Also, we have presented the region of existence of the large amplitude ion-acoustic waves by analyzing the structure of the pseudopotential. For the selected range of parameters, it is found that only positive solitary waves and double layers can exist. An analysis for the small amplitude limit through the Sagdeev pseudopotential analysis and the reductive perturbation theory shows the existence of positive and negative ion-acoustic solitary waves and double layers. The effects of positron concentration and temperature ratio on the characteristics of the solitary ion-acoustic waves and double layers (namely, the amplitude and width) are discussed in detail. The relevance of this investigation to space and laboratory plasmas is pointed out.

  20. Deflagration wave formed by ion beam, 2

    International Nuclear Information System (INIS)

    Abe, T.; Kasuya, K.; Niu, K.; Tamba, M.

    1979-06-01

    Analyses are given for structures of deflagration waves formed by ion beams in spherical targets. The singularity at the sonic point disappears in the spherical target if the beam pressure is in balance with the plasma pressure. The expanding supersonic flow of the background plasma can be connected with the subsonic flow in the core of the target through the deflagration wave. The length and the strength of the deflagration wave in the spherical target is comparable with the corresponding ones in the slab target. (author)

  1. Effects of minority ions on the propagation of the Fast Alfven wave

    International Nuclear Information System (INIS)

    Wong, K.L.; Kristiansen, M.; Hagler, M.

    1985-01-01

    Minority ions play an important role in ICRF wave heating and fast wave current drive. The former provides supplemental heating to the plasma ions, and the latter enables a Tokamak reactor to operate in steady state. The injection of minority ions greatly perturbs the propagation and absorption properties of the fast waves provided that the excitation frequency and confining magnetic field strength make the hybrid layers exist inside the plasma. A cold-plasma slab model with gradient confining magnetic field, parabolic plasma density, vacuum layer, launching antenna and conducting walls was used in studying wave propagation with and without minority ions. The wave propagation was studied individually for each discrete toroidal eigenmode (N=Rk/sub z/). There exists an asymmetric density cutoff region which is mainly due to the density variation in a single-ion plasma. The larger the torodial mode number, the larger the density cutoff region. Therefore, there exists a maximum mode number N/sub m/, which can be excited for each operating frequency. With injection of minority ions, the cutoff region for each mode number is almost unchanged. But, if one carefully chooses the excitation frequency; the hybrid layers can exist inside the plamsa for all or part of the allowed eigenmodes. Those eigenmodes with hybrid layers inside the plasma will undergo drastic change in the propagation and absorption of the waves

  2. Interaction between electromagnetic waves and plasma waves in motional plasma

    International Nuclear Information System (INIS)

    Chen, S. Y.; Gao, M.; Tang, C. J.; Peng, X. D.

    2009-01-01

    The electromagnetic wave (EM wave) behavior and the electromagnetic instability caused by the interaction between an EM wave and a plasma wave in motional plasma are studied. The dispersion relation of EM waves and the dielectric tensor of motional plasma are derived by magnetohydrodynamics, and the wave phenomenon in motional plasma is displayed. As a result, the electromagnetic instability, which is excited by the interaction between the EM waves and the plasma waves, is revealed. The mechanism of the instability is the coupling between high frequency electromagnetic field and the transverse electron oscillation derived from the deflection of longitudinal electron oscillation due to self-magnetic field. The present research is useful with regard to the new type of plasma radiation source, ion-focusing accelerator, and plasma diagnostic technique.

  3. Monte-Carlo Orbit/Full Wave Simulation of Fast Alfvén Wave (FW) Damping on Resonant Ions in Tokamaks

    Science.gov (United States)

    Choi, M.; Chan, V. S.; Tang, V.; Bonoli, P.; Pinsker, R. I.; Wright, J.

    2005-09-01

    To simulate the resonant interaction of fast Alfvén wave (FW) heating and Coulomb collisions on energetic ions, including finite orbit effects, a Monte-Carlo code ORBIT-RF has been coupled with a 2D full wave code TORIC4. ORBIT-RF solves Hamiltonian guiding center drift equations to follow trajectories of test ions in 2D axisymmetric numerical magnetic equilibrium under Coulomb collisions and ion cyclotron radio frequency quasi-linear heating. Monte-Carlo operators for pitch-angle scattering and drag calculate the changes of test ions in velocity and pitch angle due to Coulomb collisions. A rf-induced random walk model describing fast ion stochastic interaction with FW reproduces quasi-linear diffusion in velocity space. FW fields and its wave numbers from TORIC are passed on to ORBIT-RF to calculate perpendicular rf kicks of resonant ions valid for arbitrary cyclotron harmonics. ORBIT-RF coupled with TORIC using a single dominant toroidal and poloidal wave number has demonstrated consistency of simulations with recent DIII-D FW experimental results for interaction between injected neutral-beam ions and FW, including measured neutron enhancement and enhanced high energy tail. Comparison with C-Mod fundamental heating discharges also yielded reasonable agreement.

  4. Slow wave antenna coupling to ion Bernstein waves for plasma heating in ICRF

    International Nuclear Information System (INIS)

    Sy, W.N-C.; Amano, T.; Ando, R.; Fukuyama, A.; Watari, T.

    1984-10-01

    The coupling of ICRF power from a slow wave antenna to a plasma with finite temperature is examined theoretically and compared to an independent computer calculation. It is shown that such antennas can be highly efficient in trasferring most of the antenna power directly to ion Bernstein waves, with only a very small fraction going into fast waves. The potentiality of this coupling scheme for plasma heating in ICRF is briefly discussed. (author)

  5. Observation of energy-time dispersed ion structures in the magnetosheath by CLUSTER: possible signatures of transient acceleration processes at shock

    Directory of Open Access Journals (Sweden)

    P. Louarn

    Full Text Available We analyse energy-time dispersed ion signatures that have been observed by CLUSTER in the dayside magnetosheath. These events are characterized by sudden increases in the ion flux at energies larger than 10 keV. The high energy ions (30 keV are first detected, with the transition to the low energy ions (5 keV lasting about 100 s. These injections are often associated with transient plasma structures of a few minutes in duration, characterized by a hotter, less dense plasma and a diverted flow velocity, thus presenting similarities with "hot flow anomalies". They also involve modifications of the magnetic field direction, suggesting that the shock interacts with a solar wind discontinuity at the time of the event. The injections can originate from the magnetosphere or the shock region. Studying in detail a particular event, we discuss this last hypothesis. We show that the observed energy/time dispersion can be explained by combining a time-of-flight effect with a drift of the source of energetic particles along the shock. We propose that the acceleration results from a Fermi process linked to the interaction of the discontinuity with a quasi-perpendicular shock. This model explains the observed pitch-angle selection of the accelerated particles. The Fermi process acting on the beam of ions reflected from the shock appears to be sufficiently efficient to accelerate over short time scales (less than 30 s particles at energies above 30 keV.

    Key words. Magnetospheric physics (solar-wind-magnetosphere interaction; magnetosheath – Space plasma physics (shock waves

  6. Ion thermal and dispersion effects in Farley-Buneman instabilities

    International Nuclear Information System (INIS)

    Litt, S. K.; Smolyakov, A. I.; Hassan, E.; Horton, W.

    2015-01-01

    Farley-Buneman modes are an example of the collisional instability, which is thought to be the dominant mechanism for the irregularities in low ionosphere region. Despite high collisionality due to electron-neutral and ion-neutral collisions, the kinetic effects associated with finite temperature are important for determination of the mode frequencies and growth rate. This is especially important for ion component that is largely unmagnetized due to low ion cyclotron frequency. The ion thermal effects are strongly pronounced for shorter wavelengths and are crucial for the growth rate cut-off at high wavenumbers. We develop an extended fluid model for ion dynamics to incorporate the effects of ion thermal motion. The model is based on the extended MHD model that includes the evolution equations for higher order moments such as ion viscosity and ion heat flux. We also develop the generalized Chapman-Enskog closure model that provides exact linear closures based on the linearized kinetic equation. The results of these models are compared and tested against the linear kinetic model. The dispersion of Farley-Buneman modes and growth rate behavior are investigated in the short wavelength region

  7. Evaluation of P-Wave Dispersion, Diastolic Function, and Atrial Electromechanical Conduction in Pediatric Patients with Subclinical Hypothyroidism.

    Science.gov (United States)

    Irdem, Ahmet; Aydın Sahin, Derya; Kervancioglu, Mehmet; Baspinar, Osman; Sucu, Murat; Keskin, Mehmet; Kilinc, Metin

    2016-09-01

    This study aimed to evaluate ventricular diastolic dysfunction, inter- and intraatrial conduction delay, and P-wave dispersion in pediatric patients with subclinical hypothyroidism. The study comprised a total of 30 pediatric patients with subclinical hypothyroidism (SH) (mean age 7.8 ± 3.2 years) and 30 healthy children (mean age 8.4 ± 3.6 years) as the control group. A SH diagnosis was made in the event of increased serum thyroid-stimulating hormone (TSH) and decreased serum free triiodothyronine (T3 ) and free thyroxine (T4 ) concentrations. Conventional Doppler imaging (TDI) showed low mitral early diastolic E-wave velocity and E/A ratio (P wave velocity (P = 0.001) in hypothyroidism patients. Moreover, patients with hypothyroidism had significantly lower left ventricular (LV) septal Em velocity and Em /Am ratios compared with the control group (P wave dispersion was significantly different in the pediatric patients with hypothyroidism (P wave dispersion, and ventricle diastolic dysfunction in pediatric patients with hypothyroidism. © 2016, Wiley Periodicals, Inc.

  8. The dispersion relation of charge and current compensated relativistic electron beam-plasma system

    International Nuclear Information System (INIS)

    Vrba, P.; Schroetter, J.; Jarosova, P.; Koerbel, S.

    1978-01-01

    The unstable regions of relativistic electron beam-plasma system were determined by analysing the general dispersion relation numerically. The external parameters were varied to ensure more effective instability excitations. The full charge- and current compensation presumptions lead to the new synchronism predictions. The slow space charge wave and slow cyclotron wave of the return current are synchronous with the plasma ion wave. (author)

  9. Heavy-ion optical potential for sub-barrier fusion deduced from a dispersion relation

    International Nuclear Information System (INIS)

    Kim, B.T.; Kim, H.C.; Park, K.E.

    1988-01-01

    The heavy-ion energy-dependent optical potentials for the 16 O+ 208 Pb system are deduced from a dispersion relation. These potentials are used to analyze the elastic scattering, fusion, and spin distributions of compound nuclei for the system in a unified way based on the direct reaction theory. It turns out that the energy dependence of the optical potential is essential in explaining the data at near- and sub-barrier energies. The real part of the energy-dependent optical potential deduced was also used in calculating the elastic and fusion cross sections by the conventional barrier penetration model using an incoming wave boundary condition. The predictions of the elastic scattering, fusion cross sections, and the spin distributions of compound nuclei are not satisfactory compared with those from the direct reaction approach. It seems to originate from the fact that this model neglects absorption around the Coulomb barrier region

  10. P wave dispersion and maximum P wave duration are independently associated with rapid renal function decline.

    Science.gov (United States)

    Su, Ho-Ming; Tsai, Wei-Chung; Lin, Tsung-Hsien; Hsu, Po-Chao; Lee, Wen-Hsien; Lin, Ming-Yen; Chen, Szu-Chia; Lee, Chee-Siong; Voon, Wen-Chol; Lai, Wen-Ter; Sheu, Sheng-Hsiung

    2012-01-01

    The P wave parameters measured by 12-lead electrocardiogram (ECG) are commonly used as noninvasive tools to assess for left atrial enlargement. There are limited studies to evaluate whether P wave parameters are independently associated with decline in renal function. Accordingly, the aim of this study is to assess whether P wave parameters are independently associated with progression to renal end point of ≥25% decline in estimated glomerular filtration rate (eGFR). This longitudinal study included 166 patients. The renal end point was defined as ≥25% decline in eGFR. We measured two ECG P wave parameters corrected by heart rate, i.e. corrected P wave dispersion (PWdisperC) and corrected P wave maximum duration (PWdurMaxC). Heart function and structure were measured from echocardiography. Clinical data, P wave parameters, and echocardiographic measurements were compared and analyzed. Forty-three patients (25.9%) reached renal end point. Kaplan-Meier curves for renal end point-free survival showed PWdisperC > median (63.0 ms) (log-rank P = 0.004) and PWdurMaxC > median (117.9 ms) (log-rank Pfunction decline.

  11. Kinetic treatment of nonlinear ion-acoustic waves in multi-ion plasma

    Science.gov (United States)

    Ahmad, Zulfiqar; Ahmad, Mushtaq; Qamar, A.

    2017-09-01

    By applying the kinetic theory of the Valsove-Poisson model and the reductive perturbation technique, a Korteweg-de Vries (KdV) equation is derived for small but finite amplitude ion acoustic waves in multi-ion plasma composed of positive and negative ions along with the fraction of electrons. A correspondent equation is also derived from the basic set of fluid equations of adiabatic ions and isothermal electrons. Both kinetic and fluid KdV equations are stationary solved with different nature of coefficients. Their differences are discussed both analytically and numerically. The criteria of the fluid approach as a limiting case of kinetic theory are also discussed. The presence of negative ion makes some modification in the solitary structure that has also been discussed with its implication at the laboratory level.

  12. Damping-Growth Transition for Ion-Acoustic Waves in a Density Gradient

    DEFF Research Database (Denmark)

    D'Angelo, N.; Michelsen, Poul; Pécseli, Hans

    1975-01-01

    A damping-growth transition for ion-acoustic waves propagating in a nonuniform plasma (e-folding length for the density ln) is observed at a wavelength λ∼2πln. This result supports calculations performed in connection with the problem of heating of the solar corona by ion-acoustic waves generated...

  13. Improved ion acceleration via laser surface plasma waves excitation

    Energy Technology Data Exchange (ETDEWEB)

    Bigongiari, A. [CEA/DSM/LSI, CNRS, Ecole Polytechnique, 91128 Palaiseau Cedex (France); TIPS/LULI, Université Paris 6, CNRS, CEA, Ecole Polytechnique, 3, rue Galilée, 94200 Ivry-sur-Seine (France); Raynaud, M. [CEA/DSM/LSI, CNRS, Ecole Polytechnique, 91128 Palaiseau Cedex (France); Riconda, C. [TIPS/LULI, Université Paris 6, CNRS, CEA, Ecole Polytechnique, 3, rue Galilée, 94200 Ivry-sur-Seine (France); Héron, A. [CPHT, CNRS, Ecole Polytechnique, 91128 Palaiseau Cedex (France)

    2013-05-15

    The possibility of enhancing the emission of the ions accelerated in the interaction of a high intensity ultra-short (<100 fs) laser pulse with a thin target (<10λ{sub 0}), via surface plasma wave excitation is investigated. Two-dimensional particle-in-cell simulations are performed for laser intensities ranging from 10{sup 19} to 10{sup 20} Wcm{sup −2}μm{sup 2}. The surface wave is resonantly excited by the laser via the coupling with a modulation at the target surface. In the cases where the surface wave is excited, we find an enhancement of the maximum ion energy of a factor ∼2 compared to the cases where the target surface is flat.

  14. Covariant kinetic dispersion theory of linear transverse waves parallel propagating in magnetized plasmas with thermal anisotropy

    International Nuclear Information System (INIS)

    Lazar, M.; Schlickeiser, R.

    2006-01-01

    The properties of transverse waves parallel propagating in magnetized plasmas with arbitrary composition and thermally anisotropic, are investigated on the basis of relativistic Vlasov-Maxwell equations. The transverse dispersion relations for plasmas with arbitrary distribution functions are derived. These dispersion relations describe the linear response of the system to the initial perturbations and thus define all existing linear (transverse) plasma modes in the system. By analytic continuation the dispersion relations in the whole complex frequency plane are constructed. Further analysis is restricted to the important case of anisotropic bi-Maxwellian equilibrium plasma distribution functions. Explicit forms of the relativistically correct transverse dispersion relations are derived that hold for any values of the plasma temperatures and the temperature anisotropy. In the limit of nonrelativistic plasma temperatures the dispersion relations are expressed in terms of plasma dispersion function, however, the dependence on frequency and wave numbers is markedly different from the standard noncovariant nonrelativistic analysis. Only in the strictly unphysical formal limit of an infinitely large speed of light, c→∞, does the nonrelativistic dispersion relations reduce to the standard noncovariant dispersion relations

  15. The Ion Acoustic Solitary Waves and Double Layers in the Solar Wind Plasma

    Directory of Open Access Journals (Sweden)

    C. R. Choi

    2006-09-01

    Full Text Available Ion acoustic solitary wave in a plasma consisting of electrons and ions with an external magnetic field is reinvestigated using the Sagdeev's potential method. Although the Sagdeev potential has a singularity for n<1, where n is the ion number density, we obtain new solitary wave solutions by expanding the Sagdeev potential up to δ n^4 near n=1. They are compressiv (rarefactive waves and shock type solitary waves. These waves can exist all together as a superposed wave which may be used to explain what would be observed in the solar wind plasma. We compared our theoretical results with the data of the Freja satellite in the study of Wu et al.(1996. Also it is shown that these solitary waves propagate with a subsonic speed.

  16. Finite-difference modeling and dispersion analysis of high-frequency love waves for near-surface applications

    Science.gov (United States)

    Luo, Y.; Xia, J.; Xu, Y.; Zeng, C.; Liu, J.

    2010-01-01

    Love-wave propagation has been a topic of interest to crustal, earthquake, and engineering seismologists for many years because it is independent of Poisson's ratio and more sensitive to shear (S)-wave velocity changes and layer thickness changes than are Rayleigh waves. It is well known that Love-wave generation requires the existence of a low S-wave velocity layer in a multilayered earth model. In order to study numerically the propagation of Love waves in a layered earth model and dispersion characteristics for near-surface applications, we simulate high-frequency (>5 Hz) Love waves by the staggered-grid finite-difference (FD) method. The air-earth boundary (the shear stress above the free surface) is treated using the stress-imaging technique. We use a two-layer model to demonstrate the accuracy of the staggered-grid modeling scheme. We also simulate four-layer models including a low-velocity layer (LVL) or a high-velocity layer (HVL) to analyze dispersive energy characteristics for near-surface applications. Results demonstrate that: (1) the staggered-grid FD code and stress-imaging technique are suitable for treating the free-surface boundary conditions for Love-wave modeling, (2) Love-wave inversion should be treated with extra care when a LVL exists because of a lack of LVL information in dispersions aggravating uncertainties in the inversion procedure, and (3) energy of high modes in a low-frequency range is very weak, so that it is difficult to estimate the cutoff frequency accurately, and "mode-crossing" occurs between the second higher and third higher modes when a HVL exists. ?? 2010 Birkh??user / Springer Basel AG.

  17. The use of multiwavelets for uncertainty estimation in seismic surface wave dispersion.

    Energy Technology Data Exchange (ETDEWEB)

    Poppeliers, Christian [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-12-01

    This report describes a new single-station analysis method to estimate the dispersion and uncer- tainty of seismic surface waves using the multiwavelet transform. Typically, when estimating the dispersion of a surface wave using only a single seismic station, the seismogram is decomposed into a series of narrow-band realizations using a bank of narrow-band filters. By then enveloping and normalizing the filtered seismograms and identifying the maximum power as a function of frequency, the group velocity can be estimated if the source-receiver distance is known. However, using the filter bank method, there is no robust way to estimate uncertainty. In this report, I in- troduce a new method of estimating the group velocity that includes an estimate of uncertainty. The method is similar to the conventional filter bank method, but uses a class of functions, called Slepian wavelets, to compute a series of wavelet transforms of the data. Each wavelet transform is mathematically similar to a filter bank, however, the time-frequency tradeoff is optimized. By taking multiple wavelet transforms, I form a population of dispersion estimates from which stan- dard statistical methods can be used to estimate uncertainty. I demonstrate the utility of this new method by applying it to synthetic data as well as ambient-noise surface-wave cross-correlelograms recorded by the University of Nevada Seismic Network.

  18. Dispersion relations of elastic waves in one-dimensional piezoelectric/piezomagnetic phononic crystal with initial stresses.

    Science.gov (United States)

    Guo, Xiao; Wei, Peijun

    2016-03-01

    The dispersion relations of elastic waves in a one-dimensional phononic crystal formed by periodically repeating of a pre-stressed piezoelectric slab and a pre-stressed piezomagnetic slab are studied in this paper. The influences of initial stress on the dispersive relation are considered based on the incremental stress theory. First, the incremental stress theory of elastic solid is extended to the magneto-electro-elasto solid. The governing equations, constitutive equations, and boundary conditions of the incremental stresses in a magneto-electro-elasto solid are derived with consideration of the existence of initial stresses. Then, the transfer matrices of a pre-stressed piezoelectric slab and a pre-stressed piezomagnetic slab are formulated, respectively. The total transfer matrix of a single cell in the phononic crystal is obtained by the multiplication of two transfer matrixes related with two adjacent slabs. Furthermore, the Bloch theorem is used to obtain the dispersive equations of in-plane and anti-plane Bloch waves. The dispersive equations are solved numerically and the numerical results are shown graphically. The oblique propagation and the normal propagation situations are both considered. In the case of normal propagation of elastic waves, the analytical expressions of the dispersion equation are derived and compared with other literatures. The influences of initial stresses, including the normal initial stresses and shear initial stresses, on the dispersive relations are both discussed based on the numerical results. Copyright © 2015 Elsevier B.V. All rights reserved.

  19. Dispersion relation for Bernstein waves using a new transformation for the modified Bessel function

    International Nuclear Information System (INIS)

    Sato, Masumi

    1985-01-01

    Aitken's or Shanks' transformation of the exponent-modified Bessel function produces better approximations. Dispersion relations for the hybrid and Bernstein waves using these provide better thermal and parallel wavenumber corrections. They also predict more closely the evolution and mode-conversion of these waves. (author)

  20. Dispersion relation of Raman FEL with helical Wiggler and ion channel

    International Nuclear Information System (INIS)

    Hosseinalinezhad, M.; Bahmani, M.; Hasanbeigi, A.; Salehkoutahi, M.

    2012-01-01

    In this paper the theory of free electron laser with helical wiggler and ion channel guiding has been presented. The equations of motion for an electron have been analyzed. A formula for the dispersion relation is then derived in the low-gain-per-pass limit. The results of a numerical study of the growth rate enhancement due to the ion channel are presented and discussed.

  1. Nonlinear response and bistability of driven ion acoustic waves

    Science.gov (United States)

    Akbari-Moghanjoughi, M.

    2017-08-01

    The hydrodynamic model is used to obtain a generalized pseudoforce equation through which the nonlinear response of periodically driven ion acoustic waves is studied in an electron-ion plasma with isothermal and adiabatic ion fluids. The pseudotime series, corresponding to different driving frequencies, indicates that nonlinearity effects appear more strongly for smaller frequency values. The existence of extra harmonic resonances in the nonlinear amplitude spectrum is a clear indication of the interaction of an external force with harmonic components of the nonlinear ion acoustic waves. It is shown that many plasma parameters significantly and differently affect the nonlinear resonance spectrum of ion acoustic excitations. A heuristic but accurate model for the foldover effect is used which quite satisfactorily predicts the bistability of driven plasma oscillations. It is remarked that the characteristic resonance peak of isothermal ion plasma oscillations appears at lower frequencies but is stronger compared to that of adiabatic ions. Comparison of the exact numerical results for fully nonlinear and approximate (weakly nonlinear) models indicates that a weakly nonlinear model exaggerates the hysteresis and jump phenomenon for higher values of the external force amplitude.

  2. Deflagration wave formed by ion beam, 3

    International Nuclear Information System (INIS)

    Niu, Keishiro; Abe, Takashi; Tamba, Moritake.

    1980-01-01

    An analysis is given for the structure of the deflagration wave which is formed in a target bombarded by an ion beam. Stationary deflagration and/or detonation waves are formed at the surface of the target in a case in which the reaction energy of direct fusion and/or the beam energy deposited in the target are less than a critical value. On the other hand, no solution for stationary wave exists, if the energy deposited in the wave exceeds a critical value. In the latter case, the time-dependent fundamental equations reduce approximately to a self-similar type of equations. Numerical integrations are carried out for this type of differential equations, and an example of self-similar deflagration wave numerically obtained is plotted in the figures. (author)

  3. Oblique ion-acoustic cnoidal waves in two temperature superthermal electrons magnetized plasma

    International Nuclear Information System (INIS)

    Panwar, A.; Ryu, C. M.; Bains, A. S.

    2014-01-01

    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 c ,κ h , cold to hot electron temperature ratio σ, angle of propagation and ion cyclotron frequency ω 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

  4. Ion Acceleration in Plasmas with Alfven Waves

    International Nuclear Information System (INIS)

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

    2005-01-01

    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

  5. Spin-wave dispersion relations in disordered Fe-V alloys

    International Nuclear Information System (INIS)

    Nakai, Y.; Schibuya, N.; Kunitomi, N.; Wakabayashi, N.; Cooke, J.F.

    1982-01-01

    The spin-wave dispersion relations of the ferromagnetic disordered alloys Fe/sub 1-x/V/sub x/(x = 0.076, 0.135, 0.160, and 0.187) were studied by means of the inelastic scattering of neutrons. The observed dispersion relations are adequately represented by the power law, E = Dq 2 (1-βq 2 ), in a wide energy range up to 80 meV. The concentration dependence of the exchange stiffness constant D shows good agreement with previous results obtained by means of the small-angle scattering of neutrons and by the analysis of the temperature dependence of the bulk magnetization. The observed results can be explained by the Heisenberg model and, to some extent, by the itinerant-electron model

  6. Seismic velocity site characterization of 10 Arizona strong-motion recording stations by spectral analysis of surface wave dispersion

    Science.gov (United States)

    Kayen, Robert E.; Carkin, Brad A.; Corbett, Skye C.

    2017-10-19

    Vertical one-dimensional shear wave velocity (VS) profiles are presented for strong-motion sites in Arizona for a suite of stations surrounding the Palo Verde Nuclear Generating Station. The purpose of the study is to determine the detailed site velocity profile, the average velocity in the upper 30 meters of the profile (VS30), the average velocity for the entire profile (VSZ), and the National Earthquake Hazards Reduction Program (NEHRP) site classification. The VS profiles are estimated using a non-invasive continuous-sine-wave method for gathering the dispersion characteristics of surface waves. Shear wave velocity profiles were inverted from the averaged dispersion curves using three independent methods for comparison, and the root-mean-square combined coefficient of variation (COV) of the dispersion and inversion calculations are estimated for each site.

  7. Propagation and damping of mode converted ion-Bernstein waves in toroidal plasmas

    International Nuclear Information System (INIS)

    Ram, A.K.; Bers, A.

    1991-01-01

    In the heating of tokamak plasmas by waves in the ion-cyclotron range of frequencies, the fast Alfven waves launched at the plasma edge can mode convert to the ion-Bernstein waves (IBW). The propagation and damping of these mode converted waves was studied using a ray tracing code that follows the fast phase and the amplitude of the electromagnetic field along the IBW ray trajectories in a toroidal plasma. A simple analytical model is developed that describes the numerically observed features of propagation and damping of the IBW's. It is found that along the ray trajectory of the IBW there is an upshift of the poloidal mode numbers, which can lead to the electron Landau damping of the wave. This damping is dependent on the strength of the toroidal plasma current. From the properties of the upshift of the poloidal mode numbers, it is concluded that the mode converted ion-Bernstein waves are not suitable candidates for electron current drive

  8. Energy transfer between energetic ring current H(+) and O(+) by electromagnetic ion cyclotron waves

    Science.gov (United States)

    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.

  9. Ion Acoustic Waves in the Presence of Langmuir Oscillations

    DEFF Research Database (Denmark)

    Pécseli, Hans

    1976-01-01

    The dielectric function for long-wavelength, low-frequency ion acoustic waves in the presence of short-wavelength, high-frequency electron oscillations is presented, where the ions are described by the collision-free Vlasov equation. The effect of the electron oscillations can be appropriately...

  10. Suppression of transverse instabilities of dark solitons and their dispersive shock waves

    KAUST Repository

    Armaroli, Andrea; Trillo, Stefano; Fratalocchi, Andrea

    2009-01-01

    single soliton input and in the regime where dispersive shock waves develop (multisoliton regime). Such conclusions are supported by the linear stability analysis and numerical simulation of the propagation. © 2009 The American Physical Society.

  11. Enhanced loss of fast ions during mode conversion ion Bernstein wave heating in TFTR

    International Nuclear Information System (INIS)

    Darrow, D.S.; Majeski, R.; Fisch, N.J.; Heeter, R.F.; Herrmann, H.W.; Herrmann, M.C.; Zarnstorff, M.C.; Zweben, S.J.

    1995-12-01

    A strong interaction of fast ions with ion Bernstein waves has been observed in TFTR. It results in a large increase in the fast ion loss rate, and heats the lost particles to several MeV. The lost ions are observed at the passing/trapped boundary and appear to be either DD fusion produced tritons or accelerated D neutral beam ions. Under some conditions, enhanced loss of DT alpha particles is also seen. The losses provide experimental support for some of the elements required for alpha energy channeling

  12. Effect of exchange correlation potential on dispersion properties of lower hybrid wave in degenerate plasma

    Science.gov (United States)

    Rimza, Tripti; Sharma, Prerana

    2017-05-01

    The dispersion properties of lower hybrid wave are studied in electron-iondegenerate plasma with exchange effect in non-relativistic regime. It is found that the combined effect of Bohm potential and exchange correlation potential significantly modifies the dispersion properties of lower hybrid wave. The graphical results explicitly show the influence of degeneracy pressure, Bohm force and exchange correlation potential on the frequency of the lower hybrid mode. Present work should be of relevance for the dense astrophysical environments like white dwarfs and for laboratory experiments.

  13. Lithospheric Structure of the Arabian Shield from the Joint Inversion of Receiver Function and Surface-Wave Dispersion Observations

    National Research Council Canada - National Science Library

    Julia, Jordi; Ammon, Charles J; Herrimann, Robert B

    2006-01-01

    .... Receiver functions are primarily sensitive to shear-wave velocity contrasts and vertical travel times and surface-wave dispersion measurements are sensitive to vertical shear-wave velocity averages...

  14. Lithospheric Structure of the Arabian Shield From the Joint Inversion of Receiver Function and Surface-Wave Dispersion Observations

    National Research Council Canada - National Science Library

    Herrmann, Robert B; Julia, Jordi; Ammon, Charles J

    2007-01-01

    .... Receiver functions are primarily sensitive to shear-wave velocity contrast and vertical travel times and surface-wave dispersion measurements are sensitive to vertical shear-wave velocity averages...

  15. Effect of ion temperature on ion-acoustic solitary waves in a magnetized plasma in presence of superthermal electrons

    Energy Technology Data Exchange (ETDEWEB)

    Singh, S. V.; Devanandhan, S.; Lakhina, G. S. [Indian Institute of Geomagnetism, Navi Mumbai (India); Bharuthram, R. [University of the Western Cape, Bellville (South Africa)

    2013-01-15

    Obliquely propagating ion-acoustic soliatry waves are examined in a magnetized plasma composed of kappa distributed electrons and fluid ions with finite temperature. The Sagdeev potential approach is used to study the properties of finite amplitude solitary waves. Using a quasi-neutrality condition, it is possible to reduce the set of equations to a single equation (energy integral equation), which describes the evolution of ion-acoustic solitary waves in magnetized plasmas. The temperature of warm ions affects the speed, amplitude, width, and pulse duration of solitons. Both the critical and the upper Mach numbers are increased by an increase in the ion temperature. The ion-acoustic soliton amplitude increases with the increase in superthermality of electrons. For auroral plasma parameters, the model predicts the soliton speed, amplitude, width, and pulse duration, respectively, to be in the range of (28.7-31.8) km/s, (0.18-20.1) mV/m; (590-167) m, and (20.5-5.25) ms, which are in good agreement with Viking observations.

  16. Edge Ion Heating by Launched High Harmonic Fast Waves in NSTX

    International Nuclear Information System (INIS)

    Biewer, T.M.; Bell, R.E.; Diem, S.J.; Phillips, C.K.; Wilson, J.R.; Ryan, P.M.

    2004-01-01

    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 + and C 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

  17. Ion-cyclotron modes in weakly relatavistic plasmas

    International Nuclear Information System (INIS)

    Venugopal, C.; Kurian, P.J.; Renuka, G.

    1994-01-01

    We derive a dispersion relation for the perpendicular propagation of ion-cyclotron waves around the ion gyrofrequency Ω + in a weakly relativistic, anisotropic Maxwellian plasma. Using an ordering parameter ε, we separated out two dispersion relations, one of which is independent of the relativistic terms, while the other depends sensitively on them. The solutions of the former dispersion relation yield two modes: a low-frequency (LF) mode with a frequency ω + and a high-frequency (HF) mode with ω > Ω + . The plasma is stable to the propagation of these modes. The latter dispersion relation yields a new LF mode in addition to the modes supported by the non-relativistic dispersion relation. The two LF modes can coalesce to make the plasma unstable. These results are also verified numerically using a standard root solver. (author)

  18. Magnetohydrodynamic waves with relativistic electrons and positrons in degenerate spin-1/2 astrophysical plasmas

    Science.gov (United States)

    Maroof, R.; Ali, S.; Mushtaq, A.; Qamar, A.

    2015-11-01

    Linear properties of high and low frequency waves are studied in an electron-positron-ion (e-p-i) dense plasma with spin and relativity effects. In a low frequency regime, the magnetohydrodynamic (MHD) waves, namely, the magnetoacoustic and Alfven waves are presented in a magnetized plasma, in which the inertial ions are taken as spinless and non-degenerate, whereas the electrons and positrons are treated quantum mechanically due to their smaller mass. Quantum corrections associated with the spin magnetization and density correlations for electrons and positrons are re-considered and a generalized dispersion relation for the low frequency MHD waves is derived to account for relativistic degeneracy effects. On the basis of angles of propagation, the dispersion relations of different modes are discussed analytically in a degenerate relativistic plasma. Numerical results reveal that electron and positron relativistic degeneracy effects significantly modify the dispersive properties of MHD waves. Our present analysis should be useful for understanding the collective interactions in dense astrophysical compact objects, like, the white dwarfs and in atmosphere of neutron stars.

  19. Magnetohydrodynamic waves with relativistic electrons and positrons in degenerate spin-1/2 astrophysical plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Maroof, R. [Department of Physics, Abdul Wali Khan University, Mardan 23200 (Pakistan); Department of Physics, University of Peshawar, Peshawar 25000 (Pakistan); National Center for Physics (NCP) at QAU Campus, Shahdra Valley Road, Islamabad 44000 (Pakistan); Ali, S. [National Center for Physics (NCP) at QAU Campus, Shahdra Valley Road, Islamabad 44000 (Pakistan); Mushtaq, A. [Department of Physics, Abdul Wali Khan University, Mardan 23200 (Pakistan); National Center for Physics (NCP) at QAU Campus, Shahdra Valley Road, Islamabad 44000 (Pakistan); Qamar, A. [Department of Physics, University of Peshawar, Peshawar 25000 (Pakistan)

    2015-11-15

    Linear properties of high and low frequency waves are studied in an electron-positron-ion (e-p-i) dense plasma with spin and relativity effects. In a low frequency regime, the magnetohydrodynamic (MHD) waves, namely, the magnetoacoustic and Alfven waves are presented in a magnetized plasma, in which the inertial ions are taken as spinless and non-degenerate, whereas the electrons and positrons are treated quantum mechanically due to their smaller mass. Quantum corrections associated with the spin magnetization and density correlations for electrons and positrons are re-considered and a generalized dispersion relation for the low frequency MHD waves is derived to account for relativistic degeneracy effects. On the basis of angles of propagation, the dispersion relations of different modes are discussed analytically in a degenerate relativistic plasma. Numerical results reveal that electron and positron relativistic degeneracy effects significantly modify the dispersive properties of MHD waves. Our present analysis should be useful for understanding the collective interactions in dense astrophysical compact objects, like, the white dwarfs and in atmosphere of neutron stars.

  20. Interesting features of nonlinear shock equations in dissipative pair-ion-electron plasmas

    International Nuclear Information System (INIS)

    Masood, W.; Rizvi, H.

    2011-01-01

    Two dimensional nonlinear electrostatic waves are studied in unmagnetized, dissipative pair-ion-electron plasmas in the presence of weak transverse perturbation. The dissipation in the system is taken into account by incorporating the kinematic viscosity of both positive and negative ions. In the linear case, a biquadratic dispersion relation is obtained, which yields the fast and slow modes in a pair-ion-electron plasma. It is shown that the limiting cases of electron-ion and pair-ion can be retrieved from the general biquadratic dispersion relation, and the differences in the characters of the waves propagating in both the cases are also highlighted. Using the small amplitude approximation method, the nonlinear Kadomtsev Petviashvili Burgers as well as Burgers-Kadomtsev Petviashvili equations are derived and their applicability for pair-ion-electron plasma is explained in detail. The present study may have relevance to understand the formation of two dimensional electrostatic shocks in laboratory produced pair-ion-electron plasmas.

  1. Stress-dependent permeability and wave dispersion in tight cracked rocks: Experimental validation of simple effective medium models

    Science.gov (United States)

    Sarout, Joel; Cazes, Emilie; Delle Piane, Claudio; Arena, Alessio; Esteban, Lionel

    2017-08-01

    We experimentally assess the impact of microstructure, pore fluid, and frequency on wave velocity, wave dispersion, and permeability in thermally cracked Carrara marble under effective pressure up to 50 MPa. The cracked rock is isotropic, and we observe that (1) P and S wave velocities at 500 kHz and the low-strain (S waves and 9% for P waves at 1 MPa, and (4) wave dispersion virtually vanishes above 30 MPa. Assuming no interactions between the cracks, effective medium theory is used to model the rock's elastic response and its permeability. P and S wave velocity data are jointly inverted to recover the crack density and effective aspect ratio. The permeability data are inverted to recover the cracks' effective radius. These parameters lead to a good agreement between predicted and measured wave velocities, dispersion and permeability up to 50 MPa, and up to a crack density of 0.5. The evolution of the crack parameters suggests that three deformation regimes exist: (1) contact between cracks' surface asperities up to 10 MPa, (2) progressive crack closure between 10 and 30 MPa, and (3) crack closure effectively complete above 30 MPa. The derived crack parameters differ significantly from those obtained by analysis of 2-D electron microscope images of thin sections or 3-D X-ray microtomographic images of millimeter-size specimens.

  2. Two markers in predicting the cardiovascular events in patients with polycystic ovary syndrome: increased P-wave and QT dispersion.

    Science.gov (United States)

    Akdag, S; Cim, N; Yildizhan, R; Akyol, A; Ozturk, F; Babat, N

    2015-09-01

    Polycystic ovary syndrome (PCOS) is a prevalent disease with many potential long-term cardiovascular risks. P-wave dispersion (Pdis) and QT dispersion (QTdis) have been shown to be noninvasive electrocardiographic predictors for development of cardiac arrhythmias. In this study we aimed to search Pdis and QTdis parameters in patients with PCOS. The study included 82 patients with PCOS and 74 age- and sex-matched healthy controls. Baseline 12-lead electrocardiographic and transthoracic echocardiographic measurements were evaluated. P-wave maximum duration (Pmax), P-wave minimum duration (Pmin), Pdis, QT interval, heart rate-corrected QT dispersion and QTdis were calculated by two cardiologists. Patients wirh PCOS had significantly higher QT dispersion (49.5 ± 14.1 vs. 37.9 ± 12.6 ms, p PCOS patients.

  3. Ion acoustic waves and double-layers in electronegative expanding plasmas

    International Nuclear Information System (INIS)

    Plihon, Nicolas; Chabert, Pascal

    2011-01-01

    Ion acoustic waves and double-layers are observed in expanding plasmas in electronegative gases, i.e., plasmas containing an appreciable fraction of negative ions. The reported experiments are performed in argon gas with a variable amount of SF 6 . When varying the amount of SF 6 , the negative ion fraction increases and three main regimes were identified previously: (i) the plasma smoothly expands at low negative ion fraction, (ii) a static double-layer (associated with an abrupt potential drop and ion acceleration) forms at intermediate negative ion fraction, (iii) double-layers periodically form and propagate (in the plasma expansion direction) at high negative ion fraction. In this paper, we show that transition phases exist in between these regimes, where fluctuations are observed. These fluctuations are unstable slow ion acoustic waves, propagating in the direction opposite to the plasma expansion. These fluctuations are excited by the most unstable eigenmodes and display turbulent features. It is suggested that the static double layer forms when the ion acoustic fluctuations become non-linearly unstable: the double layer regime being a bifurcated state of the smoothly expanding regime. For the highest negative ion fraction, a coexistence of (upstream propagating) slow ion acoustic fluctuations and (downstream) propagating double layers was observed.

  4. On the energy flux of stationary electromagnetic waves in anisotropic dissipative media with spatial dispersion

    NARCIS (Netherlands)

    Tokman, M. D.; Westerhof, E.; Gavrilova, M. A.

    2000-01-01

    The special features of the propagation of electromagnetic waves in gyrotropic medium with dispersion and resonant dissipation (specifically, in a magnetoactive plasma) are studied. Even though the anti-Hermitian components of the permittivity tensor are substantial in magnitude, weakly damped waves

  5. Wave dispersion of carbon nanotubes conveying fluid supported on linear viscoelastic two-parameter foundation including thermal and small-scale effects

    Science.gov (United States)

    Sina, Nima; Moosavi, Hassan; Aghaei, Hosein; Afrand, Masoud; Wongwises, Somchai

    2017-01-01

    In this paper, for the first time, a nonlocal Timoshenko beam model is employed for studying the wave dispersion of a fluid-conveying single-walled carbon nanotube on Viscoelastic Pasternak foundation under high and low temperature change. In addition, the phase and group velocity for the nanotube are discussed, respectively. The influences of Winkler and Pasternak modulus, homogenous temperature change, steady flow velocity and damping factor of viscoelastic foundation on wave dispersion of carbon nanotubes are investigated. It was observed that the characteristic of the wave for carbon nanotubes conveying fluid is the normal dispersion. Moreover, implying viscoelastic foundation leads to increasing the wave frequencies.

  6. Measurements of the power spectrum and dispersion relation of self-excited dust acoustic waves

    Science.gov (United States)

    Nosenko, V.; Zhdanov, S. K.; Kim, S.-H.; Heinrich, J.; Merlino, R. L.; Morfill, G. E.

    2009-12-01

    The spectrum of spontaneously excited dust acoustic waves was measured. The waves were observed with high temporal resolution using a fast video camera operating at 1000 frames per second. The experimental system was a suspension of micron-size kaolin particles in the anode region of a dc discharge in argon. Wave activity was found at frequencies as high as 450 Hz. At high wave numbers, the wave dispersion relation was acoustic-like (frequency proportional to wave number). At low wave numbers, the wave frequency did not tend to zero, but reached a cutoff frequency instead. The cutoff value declined with distance from the anode. We ascribe the observed cutoff to the particle confinement in this region.

  7. Dispersive shock waves in Bose-Einstein condensates and nonlinear nano-oscillators in ferromagnetic thin films

    Science.gov (United States)

    Hoefer, Mark A.

    This thesis examines nonlinear wave phenomena, in two physical systems: a Bose-Einstein condensate (BEC) and thin film ferromagnets where the magnetization dynamics are excited by the spin momentum transfer (SMT) effect. In the first system, shock waves generated by steep gradients in the BEC wavefunction are shown to be of the disperse type. Asymptotic and averaging methods are used to determine shock speeds and structure in one spatial dimension. These results are compared with multidimensional numerical simulations and experiment showing good, qualitative agreement. In the second system, a model of magnetization dynamics due to SMT is presented. Using this model, nonlinear oscillating modes---nano-oscillators---are found numerically and analytically using perturbative methods. These results compare well with experiment. A Bose-Einstein condensate (BEC) is a quantum fluid that gives rise to interesting shock wave nonlinear dynamics. Experiments depict a BEC that exhibits behavior similar to that of a shock wave in a compressible gas, e.g. traveling fronts with steep gradients. However, the governing Gross-Pitaevskii (GP) equation that describes the mean field of a BEC admits no dissipation hence classical dissipative shock solutions do not explain the phenomena. Instead, wave dynamics with small dispersion is considered and it is shown that this provides a mechanism for the generation of a dispersive shock wave (DSW). Computations with the GP equation are compared to experiment with excellent agreement. A comparison between a canonical 1D dissipative and dispersive shock problem shows significant differences in shock structure and shock front speed. Numerical results associated with laboratory experiments show that three and two-dimensional approximations are in excellent agreement and one dimensional approximations are in qualitative agreement. The interaction of two DSWs is investigated analytically and numerically. Using one dimensional DSW theory it is argued

  8. Dust-acoustic shock waves in a charge varying electronegative magnetized dusty plasma with nonthermal ions: Application to Halley Comet plasma

    Energy Technology Data Exchange (ETDEWEB)

    Tribeche, Mouloud; Bacha, Mustapha [Plasma Physics Group (PPG), Theoretical Physics Laboratory (TPL), Faculty of Physics, University of Bab-Ezzouar, USTHB, B. P. 32, El Alia, Algiers 16111 (Algeria)

    2013-10-15

    Weak dust-acoustic waves (DAWs) are addressed in a nonthermal charge varying electronegative magnetized dusty plasmas with application to the Halley Comet. A weakly nonlinear analysis is carried out to derive a Korteweg-de Vries-Burger equation. The positive ion nonthermality, the obliqueness, and magnitude of the magnetic field are found to modify the dispersive and dissipative properties of the DA shock structure. Our results may aid to explain and interpret the nonlinear oscillations that may occur in the Halley Comet Plasma.

  9. Quantum ion-acoustic solitary waves in weak relativistic plasma

    Indian Academy of Sciences (India)

    Abstract. Small amplitude quantum ion-acoustic solitary waves are studied in an unmagnetized two- species relativistic quantum plasma system, comprised of electrons and ions. The one-dimensional quantum hydrodynamic model (QHD) is used to obtain a deformed Korteweg–de Vries (dKdV) equation by reductive ...

  10. Observations of linear and nonlinear processes in the foreshock wave evolution

    Directory of Open Access Journals (Sweden)

    Y. Narita

    2007-07-01

    Full Text Available Waves in the foreshock region are studied on the basis of a hypothesis that the linear process first excites the waves and further wave-wave nonlinearities distribute scatter the energy of the primary waves into a number of daughter waves. To examine this wave evolution scenario, the dispersion relations, the wave number spectra of the magnetic field energy, and the dimensionless cross helicity are determined from the observations made by the four Cluster spacecraft. The results confirm that the linear process is the ion/ion right-hand resonant instability, but the wave-wave interactions are not clearly identified. We discuss various reasons why the test for the wave-wave nonlinearities fails, and conclude that the higher order statistics would provide a direct evidence for the wave coupling phenomena.

  11. Relation of wave energy and momentum with the plasma dispersion relation in an inhomogeneous plasma

    International Nuclear Information System (INIS)

    Berk, H.L.; Pfirsch, D.

    1988-01-01

    The expressions for wave energy and angular momentum commonly used in homogeneous and near-homogeneous media is generalized to inhomogeneous media governed by a nonlocal conductivity tensor. The expression for wave energy applies to linear excitations in an arbitrary three-dimensional equilibrium, while the expression for angular momentum applies to linear excitations of azimuthally symmetric equilibria. The wave energy E-script/sub wave/ is interpreted as the energy transferred from linear external sources to the plasma if there is no dissipation. With dissipation, such a simple interpretation is lacking as energy is also thermally absorbed. However, for azimuthally symmetric equilibria, the expression for the wave energy in a frame rotating with a frequency ω can be unambiguously separated from thermal energy. This expression is given by E-script/sub wave/ -ωL/sub wave/ l, where L/sub wave/ is the wave angular momentum defined in the text and l the azimuthal wavenumber and it is closely related to the real part of a dispersion relation for marginal stability. The imaginary part of the dispersion is closely related to the energy input into a system. Another useful quantity discussed is the impedance form, which can be used for three-dimensional equilibrium without an ignorable coordinate and the expression is closely related to the wave impedance used in antenna theory. Applications to stability theory are also discussed

  12. Impact localization in dispersive waveguides based on energy-attenuation of waves with the traveled distance

    Science.gov (United States)

    Alajlouni, Sa'ed; Albakri, Mohammad; Tarazaga, Pablo

    2018-05-01

    An algorithm is introduced to solve the general multilateration (source localization) problem in a dispersive waveguide. The algorithm is designed with the intention of localizing impact forces in a dispersive floor, and can potentially be used to localize and track occupants in a building using vibration sensors connected to the lower surface of the walking floor. The lower the wave frequencies generated by the impact force, the more accurate the localization is expected to be. An impact force acting on a floor, generates a seismic wave that gets distorted as it travels away from the source. This distortion is noticeable even over relatively short traveled distances, and is mainly caused by the dispersion phenomenon among other reasons, therefore using conventional localization/multilateration methods will produce localization error values that are highly variable and occasionally large. The proposed localization approach is based on the fact that the wave's energy, calculated over some time window, decays exponentially as the wave travels away from the source. Although localization methods that assume exponential decay exist in the literature (in the field of wireless communications), these methods have only been considered for wave propagation in non-dispersive media, in addition to the limiting assumption required by these methods that the source must not coincide with a sensor location. As a result, these methods cannot be applied to the indoor localization problem in their current form. We show how our proposed method is different from the other methods, and that it overcomes the source-sensor location coincidence limitation. Theoretical analysis and experimental data will be used to motivate and justify the pursuit of the proposed approach for localization in a dispersive medium. Additionally, hammer impacts on an instrumented floor section inside an operational building, as well as finite element model simulations, are used to evaluate the performance of

  13. Theory for nonlinear magnetosonic waves in a two-ion-species plasma

    International Nuclear Information System (INIS)

    Toida, Mieko; Ohsawa, Yukiharu

    1997-01-01

    Magnetosonic waves propagating perpendicular to a magnetic field in a plasma containing two ion species is studied theoretically. The magnetosonic wave is split into two modes in a two-ion-species plasma; low- and high- frequency modes. The frequency of the low-frequency mode tends to zero as the wave number k goes to zero. A KdV equation is derived for this mode by the conventional reductive perturbation method. The frequency of high-frequency mode does not go to zero as k → 0. However, using a new expansion scheme, a KdV equation for the nonlinear high-frequency mode has also been derived. This shows that KdV equations are not limited to waves whose frequencies tend to zero as k → 0. The KdV equation for the low-frequency mode is valid when the amplitudes ε are quite small, while that for the high-frequency mode is valid when (m. e /m. i ) 1/2 e /m. i is a measure of electron-to-ion mass ratios. The characteristic soliton widths are the ion inertia length for the low-frequency mode and the electron skin depth for the high-frequency mode. (author)

  14. Deterministic and stochastic evolution equations for fully dispersive and weakly nonlinear waves

    DEFF Research Database (Denmark)

    Eldeberky, Y.; Madsen, Per A.

    1999-01-01

    and stochastic formulations are solved numerically for the case of cross shore motion of unidirectional waves and the results are verified against laboratory data for wave propagation over submerged bars and over a plane slope. Outside the surf zone the two model predictions are generally in good agreement......This paper presents a new and more accurate set of deterministic evolution equations for the propagation of fully dispersive, weakly nonlinear, irregular, multidirectional waves. The equations are derived directly from the Laplace equation with leading order nonlinearity in the surface boundary...... is significantly underestimated for larger wave numbers. In the present work we correct this inconsistency. In addition to the improved deterministic formulation, we present improved stochastic evolution equations in terms of the energy spectrum and the bispectrum for multidirectional waves. The deterministic...

  15. How valuable is P-wave dispersion in the determination of carboxyhemoglobin levels?

    Science.gov (United States)

    Sener, M T; Anci, Y; Kalkan, K; Kir, M Z; Emet, M

    2014-05-01

    To determine whether or not wave/interval dispersions in electrocardiography (ECG) are increased, and to define whether wave and interval dispersions are correlated with carboxyhemoglobin (COHb) levels. ECG, complete blood count, and biochemical parameters were taken from 87 patients with carbon monoxide (CO) poisoning as well as 90 control patients with similar age, gender, and body mass index distribution. COHb levels were recorded in CO-poisoning patients. The COHb levels and the relationships with ECG parameters were studied. Pmax, Pmin, Pd, PRmax, PRmin, PRd, QTmax, QTmin, QTd, cQTmax, cQTmin, cQTd, Tmax, Tmin, and Td in ECG were higher in intoxicated patients than the control group (p < 0.05 for all). Pearson's correlation analyses showed moderately significant positive correlations between COHb level and Pmax (r = 0.224; p = 0.037) and Pd (r = 0.222; p = 0.039). The receiver-operator characteristic (ROC) curve showed that a Pd value of 38 ms determined by ECG separates patients with a COHb ≥ 20% with area under the ROC curve of 0.78 (95%CI = 0.71-0.83), a sensitivity of 67.9% (95%CI = 59.4-75.6), a specificity of 95% (95%CI = 83.0-99.2], a positive predictive value of 97.9% (95%CI = 92.5-99.7), and a negative predictive value of 46.3% (95%CI = 35.3-57.7.) A significant increase in wave/interval dispersions in the ECG of CO-poisoning patients compared with controls may show that not only a part is affected but both atrium and the ventricles as a whole are affected by hypoxic ischemia. When COHb levels of the patients are unavailable, P dispersion on ECG may show CO poisoning level of the patient.

  16. Reflection and absorption of ion-acoustic waves in a plasma density gradient

    International Nuclear Information System (INIS)

    Ishihara, O.

    1977-01-01

    Plasma is characterized by electrical quasineutrality and the collective behavior. There exists a longitudinal low-frequency wave called an ion-acoustic wave in a plasma. One problem in the experimental study of ion-acoustic waves has been that sometimes they are observed to be reflected from discharge tube walls, and sometimes to be absorbed. Theoretical computation reveals that a velocity gradient produced by a density gradient plays a significant role in the reflection. The velocity gradient produces the subsonic-supersonic transition and long wavelength waves are reflected before reaching the transition while short wavelength waves penetrate over the transition and are absorbed in the supersonic flow plasma

  17. Study of ion cyclotron fluctuations. Application to the measurement of the ion temperature

    International Nuclear Information System (INIS)

    Lehner, T.

    1982-02-01

    A diagnostic technique for measuring the ion temperature of tokamak-type plasmas was developed. A theoretical study was made of the form factor associated with the ion cyclotron waves; the influence of Te/Ti on the frequency of the extrema of the dispersion relations was demonstrated. The different effects able to modify the spectral density (in particular the drift velocity and the impurities) were investigated. The mechanisms of suprathermal excitation of cylotron waves in tokamaks were reviewed together with the various effects stabilizing the spectrum: collisions, shear of the magnetic field lines. The experimental realization of the diagnostic technique is based on Thomson scattering by the electron density fluctuations [fr

  18. Identification of low-frequency kinetic wave modes in the Earth's ion foreshock

    Directory of Open Access Journals (Sweden)

    X. Blanco-Cano

    Full Text Available In this work we use ion and magnetic field data from the AMPTE-UKS mission to study the characteristics of low frequency (ωr « Ωp waves observed upstream of the Earth's bow shock. We test the application of various plasma-field correlations and magnetic ratios derived from linear Vlasov theory to identify the modes in this region. We evaluate (for a parameter space consistent with the ion foreshock the Alfvén ratio, the parallel compressibility, the cross-helicity, the noncoplanar ratio, the magnetic compression and the polarization for the two kinetic instabilities that can be generated in the foreshock by the interaction of hot diffuse ions with the solar wind: the left-hand resonant and the right-hand resonant ion beam instabilities. Comparison of these quantities with the observed plasma-field correlations and various magnetic properties of the waves observed during 10 intervals on 30 October 1984, where the waves are associated with diffuse ions, allows us to identify regions with Alfvénic waves and regions where the predominant mode is the right-hand resonant instability. In all the cases the waves are transverse, propagating at angles ≤ 33° and are elliptically polarized. Our results suggest that while the observed Alfvén waves are generated locally by hot diffuse ions, the right-handed waves may result from the superposition of waves generated by two different types of beam distribution (i.e. cold beam and diffuse ions. Even when there was good agreement between the values of observed transport ratios and the values given by the theory, some discrepancies were found. This shows that the observed waves are different from the theoretical modes and that mode identification based only on polarization quantities does not give a complete picture of the waves' characteristics and can lead to mode identification of waves whose polarization may agree with theoretical predictions even when

  19. Cluster observations of EMIC triggered emissions in association with Pc1 waves near Earth's plasmapause

    Science.gov (United States)

    Pickett, J. S.; Grison, B.; Omura, Y.; Engebretson, M. J.; Dandouras, I.; Masson, A.; Adrian, M. L.; Santolík, O.; Décréau, P. M. E.; Cornilleau-Wehrlin, N.; Constantinescu, D.

    2010-05-01

    The Cluster spacecraft were favorably positioned on the nightside near the equatorial plasmapause of Earth at L ˜ 4.3 on 30 March 2002 to observe electromagnetic ion cyclotron (EMIC) rising tone emissions in association with Pc1 waves at 1.5 Hz. The EMIC rising tone emissions were found to be left-hand, circularly polarized, dispersive, and propagating away from the equator. Their burstiness and dispersion of ˜30s/Hz rising out of the 1.5 Hz Pc1 waves are consistent with their identification as EMIC triggered chorus emissions, the first to be reported through in situ observations near the plasmapause. Along with the expected H+ ring current ions seen at higher energies (>300 eV), lower energy ions (300 eV and less) were observed during the most intense EMIC triggered emission events. Nonlinear wave-particle interactions via cyclotron resonance between the ˜2-10 keV H+ ions with temperature anisotropy and the linearly-amplified Pc1 waves are suggested as a possible generation mechanism for the EMIC triggered emissions.

  20. The influence of the directional energy distribution on the nonlinear dispersion relation in a random gravity wave field

    Science.gov (United States)

    Huang, N. E.; Tung, C.-C.

    1977-01-01

    The influence of the directional distribution of wave energy on the dispersion relation is calculated numerically using various directional wave spectrum models. The results indicate that the dispersion relation varies both as a function of the directional energy distribution and the direction of propagation of the wave component under consideration. Furthermore, both the mean deviation and the random scatter from the linear approximation increase as the energy spreading decreases. Limited observational data are compared with the theoretical results. The agreement is favorable.

  1. Non-axial-symmetric Alfven waves in cylindrical, radial inhomogeneous plasmas

    International Nuclear Information System (INIS)

    Raeuchle, E.

    1978-08-01

    The propagation of nonaxialsymmetric Alfven waves is investigated theoretically. Eigenfunctions and dispersion relations are calculated numerically for radial inhomogeneous cylindrical plasmas. In the MHD treatment resistivity, neutral particle loading and ion cyclotron effects are included. The investigations are of importance for plasma heating by Alfven waves. (orig.) [de

  2. P-wave dispersion and its relationship to aortic stiffness in patients with acute myocardial infarction after cardiac rehabilitation

    Directory of Open Access Journals (Sweden)

    Rezzan Deniz Acar

    2014-07-01

    Full Text Available BACKGROUND: The aim of our study was to investigate the P-wave dispersion from standard electrocardiograms (ECGs in patients with acute myocardial infarction (AMI after cardiac rehabilitation (CR and determine its relation to arterial stiffness. METHODS: This is a prospective study included 33 patients with AMI and successfully re-vascularized by percutaneous coronary intervention (PCI underwent CR. Left ventricular ejection fraction (LVEF was measured by biplane Simpson’s method. Left atrium (LA volume was calculated. The maximum and minimum durations of P-waves (Pmax and Pmin, respectively were detected, and the difference between Pmax and Pmin was defined as P-wave dispersion (Pd = Pmax–Pmin. Aortic elasticity parameters were measured. RESULTS: LVEF was better after CR. The systolic and diastolic blood pressures decreased after CR, these differences were statistically significant. With exercise training, LA volume decreased significantly. Pmax and Pd values were significantly shorter after the CR program. The maximum and minimum P-waves and P-wave dispersion after CR were 97 ± 6 ms, 53 ± 5 ms, and 44 ± 5 ms, respectively. Aortic strain and distensibility increased and aortic stiffness index was decreased significantly. Aortic stiffness index was 0.4 ± 0.2 versus 0.3 ± 0.2, P = 0.001. Aortic stiffness and left atrial volume showed a moderate positive correlation with P-wave dispersion (r = 0.52, P = 0.005; r = 0.64, P = 0.000, respectively. CONCLUSION: This study showed decreased arterial stiffness indexes in AMI patient’s participated CR, with a significant relationship between the electromechanical properties of the LA that may raise a question of the preventive effect of CR from atrial fibrillation and stroke in patients with acute myocardial infarction.   Keywords: Cardiac Rehabilitation, P-Wave Dispersion, Aortic Stiffness, Acute Myocardial Infarction 

  3. Measurements of ion cyclotron range of frequencies mode converted wave intensity with phase contrast imaging in Alcator C-Mod and comparison with full-wave simulations

    International Nuclear Information System (INIS)

    Tsujii, N.; Porkolab, M.; Bonoli, P. T.; Lin, Y.; Wright, J. C.; Wukitch, S. J.; Jaeger, E. F.; Green, D. L.; Harvey, R. W.

    2012-01-01

    Radio frequency waves in the ion cyclotron range of frequencies (ICRF) are widely used to heat tokamak plasmas. In ICRF heating schemes involving multiple ion species, the launched fast waves convert to ion cyclotron waves or ion Bernstein waves at the two-ion hybrid resonances. Mode converted waves are of interest as actuators to optimise plasma performance through current drive and flow drive. In order to describe these processes accurately in a realistic tokamak geometry, numerical simulations are essential, and it is important that these codes be validated against experiment. In this study, the mode converted waves were measured using a phase contrast imaging technique in D-H and D- 3 He plasmas. The measured mode converted wave intensity in the D- 3 He mode conversion regime was found to be a factor of ∼50 weaker than the full-wave predictions. The discrepancy was reduced in the hydrogen minority heating regime, where mode conversion is weaker.

  4. Polarization waves in dielectric films with spatial dispersion

    International Nuclear Information System (INIS)

    Jardin, Jean-Pierre; Moch, Philippe; Dvorak, Vladimir

    2002-01-01

    The polarization waves propagating in a slab-shaped or in a semi-infinite dielectric medium with spatial dispersion characterized by a volume free-energy density and by a boundary-surface energy density are studied, taking into account Maxwell's equations, in the framework of the Landau-Ginzburg formalism. It is shown that two independent extrapolation lengths providing for the required additional boundary conditions need to be specified at each surface limiting the medium. Complete calculations are performed in the electrostatic approximation: they provide evidence of the differences between the transverse in-plane polarized modes (s modes) and the sagittal plane polarized modes (p modes). True surface modes exist only in the case of negative extrapolation lengths. A detailed analysis of the symmetry properties of the surface and of the guided bulk modes in a slab is developed. Finally, our results are compared with those from previous models describing the boundary conditions in media where spatial dispersion is present. (author)

  5. Coherent structural trapping through wave packet dispersion during photoinduced spin state switching

    DEFF Research Database (Denmark)

    Lemke, Henrik T.; Kjær, Kasper Skov; Hartsock, Robert

    2017-01-01

    The description of ultrafast nonadiabatic chemical dynamics during molecular photo-transformations remains challenging because electronic and nuclear configurations impact each other and cannot be treated independently. Here we gain experimental insights, beyond the Born-Oppenheimer approximation...... is distinguished from the structural trapping dynamics, which launches a coherent oscillating wave packet (265 fs period), clearly identified as molecular breathing. Throughout the structural trapping, the dispersion of the wave packet along the reaction coordinate reveals details of intramolecular vibronic...

  6. Experimental observation of strong coupling effects on the dispersion of dust acoustic waves in a plasma

    OpenAIRE

    Bandyopadhyay, P.; Prasad, G.; Sen, A.; Kaw, P. K.

    2016-01-01

    The dispersion properties of low frequency dust acoustic waves in the strong coupling regime are investigated experimentally in an argon plasma embedded with a mixture of kaolin and $MnO_2$ dust particles. The neutral pressure is varied over a wide range to change the collisional properties of the dusty plasma. In the low collisional regime the turnover of the dispersion curve at higher wave numbers and the resultant region of $\\partial\\omega/\\partial k < 0$ are identified as signatures of du...

  7. Comparison of P-wave dispersion in healthy dogs, dogs with chronic valvular disease and dogs with disturbances of supraventricular conduction

    Directory of Open Access Journals (Sweden)

    Nicpoń Józef

    2011-03-01

    Full Text Available Abstract Background P-wave dispersion (Pd is a new ECG index used in human cardiology and veterinary medicine. It is defined as the difference between the maximum and the minimum P-wave duration recorded from multiple different ECG leads. So far no studies were performed assessing the importance of P-wave dispersion in dogs. Methods The current study was aimed at determining proper value of Pd in healthy dogs (group I, dogs with chronic valvular disease (group II and dogs with disturbances of supraventricular conduction (group III. The tests were carried out in 53 healthy dogs, 23 dogs with chronic valvular disease and 12 dogs with disturbances of supraventricular conduction of various breeds, sexes and body weight from 1,5 to 80 kg, aged between 0,5 and 17 years, submitted to the ECG examination. ECG was acquired in dogs in a standing position with BTL SD-8 electrocardiographic device and analyzed once the recording was enlarged. P-wave duration was calculated in 9 ECG leads (I, II, III, aVR, aVL, aVF, V1, V2, V4 from 5 cardiac cycles. Results The proper P-wave dispersion in healthy dogs was determined at up to 24 ms. P-wave dispersion was statistically significant increased (p Conclusions The P-wave dispersion is a constant index in healthy dogs, that is why it can be used for evaluating P wave change in dogs with chronic valvular disease and in dogs with disturbances of supraventricular conduction.

  8. Nonlinear Electron Waves in Strongly Magnetized Plasmas

    DEFF Research Database (Denmark)

    Pécseli, Hans; Juul Rasmussen, Jens

    1980-01-01

    Weakly nonlinear dispersive electron waves in strongly magnetized plasma are considered. A modified nonlinear Schrodinger equation is derived taking into account the effect of particles resonating with the group velocity of the waves (nonlinear Landau damping). The possibility of including the ion...... dynamics in the analysis is also demonstrated. As a particular case the authors investigate nonlinear waves in a strongly magnetized plasma filled wave-guide, where the effects of finite geometry are important. The relevance of this problem to laboratory experiments is discussed....

  9. Quantum corrections to nonlinear ion acoustic wave with Landau damping

    Energy Technology Data Exchange (ETDEWEB)

    Mukherjee, Abhik; Janaki, M. S. [Saha Institute of Nuclear Physics, Calcutta (India); Bose, Anirban [Serampore College, West Bengal (India)

    2014-07-15

    Quantum corrections to nonlinear ion acoustic wave with Landau damping have been computed using Wigner equation approach. The dynamical equation governing the time development of nonlinear ion acoustic wave with semiclassical quantum corrections is shown to have the form of higher KdV equation which has higher order nonlinear terms coming from quantum corrections, with the usual classical and quantum corrected Landau damping integral terms. The conservation of total number of ions is shown from the evolution equation. The decay rate of KdV solitary wave amplitude due to the presence of Landau damping terms has been calculated assuming the Landau damping parameter α{sub 1}=√(m{sub e}/m{sub i}) to be of the same order of the quantum parameter Q=ℏ{sup 2}/(24m{sup 2}c{sub s}{sup 2}L{sup 2}). The amplitude is shown to decay very slowly with time as determined by the quantum factor Q.

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

    Science.gov (United States)

    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…

  11. Upconversion of whistler waves by gyrating ion beams in a plasma

    Indian Academy of Sciences (India)

    It is shown that a gyrating ion-beam frequency upconverts the whistler waves separated by harmonics of beam gyro-frequency. The expression for the growth rate of whistler mode waves has been derived. In Case 1, a high-amplitude whistler wave decays into two lower frequency waves, called a low-frequency mode and a ...

  12. Nonlinear waves in electron–positron–ion plasmas including charge ...

    Indian Academy of Sciences (India)

    2017-01-04

    Jan 4, 2017 ... The introduction of the Poisson equation increased the Mach number required to generate the waveforms but the driving electric field E0 was reduced. The results are compared with satellite observations. Keywords. Nonlinear waves; low frequency; ion-acoustic waves. PACS Nos 52.35.Qz; 52.35.Fp; 52.35 ...

  13. Higher P-Wave Dispersion in Migraine Patients with Higher Number of Attacks

    Directory of Open Access Journals (Sweden)

    A. Koçer

    2012-01-01

    Full Text Available Objective and Aim. An imbalance of the sympathetic system may explain many of the clinical manifestations of the migraine. We aimed to evaluate P-waves as a reveal of sympathetic system function in migraine patients and healthy controls. Materials and Methods. Thirty-five episodic type of migraine patients (complained of migraine during 5 years or more, BMI < 30 kg/m2 and 30 controls were included in our study. We measured P-wave durations (minimum, maximum, and dispersion from 12-lead ECG recording during pain-free periods. ECGs were transferred to a personal computer via a scanner and then used for magnification of x400 by Adobe Photoshop software. Results. P-wave durations were found to be similar between migraine patients and controls. Although P WD (P-wave dispersion was similar, the mean value was higher in migraine subjects. P WD was positively correlated with P max (P<0.01. Attacks number per month and male gender were the factors related to the P WD (P<0.01. Conclusions. Many previous studies suggested that increased sympathetic activity may cause an increase in P WD. We found that P WD of migraine patients was higher than controls, and P WD was related to attacks number per month and male gender. Further studies are needed to explain the chronic effects of migraine.

  14. Plasma wave observations during electron and ion gun experiments

    International Nuclear Information System (INIS)

    Olsen, R.C.; Lowery, D.R.; Weddle, L.E.

    1988-01-01

    Plasma wave instruments with high temporal and frequency resolution in the 0-6 kHz frequency range have been used to monitor electron gun-employing charge control experiments with the USAF/NASA p78-2 satellite, in order to determine whether plasma wave signatures consistent with the previous inference of electron heating were present. Strong plasma waves were noted near the electron gyrofrequency; these waves can heat ambient low energy electrons, as previously inferred. Attention is given to the two distinct classes of behavior revealed by the ion gun experiments. 16 references

  15. Loss-cone-driven ion cyclotron waves in the magnetosphere

    International Nuclear Information System (INIS)

    Denton, R.E.; Hudson, M.K.; Roth, I.

    1992-01-01

    The theoretical properties of linear ion cyclotron waves propagating in the magnetosphere at arbitrary angles to the background magnetic field are explored. It is found that in some cases the linear wave growth of modes with oblique propagation can dominate that of the parallel propagating electromagnetic ion cyclotron (EMIC) wave. In particular, when the hot ring current protons have a loss cone and their temperature anisotropy A ≡ T perpendicular /T parallel - 1 is reduced, the parallel propagating EMIC wave becomes stable, while the obliquely propagating loss-cone-driven mode persists. The growth rate of the loss-cone-driven model depends strongly on the depth of the loss cone. Unlike the parallel propagating EMIC wave, it can be unstable with A = 0. Other conditions that favor the loss-cone-driven mode in comparison to the parallel mode are stronger background magnetic field, lower density of cold hydrogen, and a lower temperature for the hot anisotropic component of hydrogen. A simple analytical theory is presented which explains the scaling of the growth rate of the oblique mode with respect to various parameters. The loss-cone-driven mode is an electromagnetic mode which is preferentially nearly linearly polarized. It is nearly electrostatic in the sense that the wave electric field is aligned with the perpendicular (to B 0 ) component of the wave vector k and k perpendicular > k parallel . Since the electric and magnetic wave fields are perpendicular to B 0 , they would be difficult to distinguish from those of a linearly polarized parallel propagating electromagnetic wave with the same k parallel

  16. Joint Inversion of Surface Waves Dispersion and Receiver Function at Cuba Seismic Stations

    International Nuclear Information System (INIS)

    Gonzalez, O'Leary; Moreno, Bladimir; Romanelli, Fabio; Panza, Giuliano F.

    2010-06-01

    Joint inversion of Rayleigh wave group velocity dispersion and receiver functions have been used to estimate the crust and upper mantle structure at eight seismic stations in Cuba. Receiver functions have been computed from teleseismic recordings of earthquakes at epicentral (angular) distances between 30 o and 90 o and Rayleigh wave group velocity dispersion have been taken from a surface-wave tomography study of the Caribbean area. The thickest crust (around 27 km) is found at Cascorro (CCC), Soroa (SOR), Moa (MOA) and Maisi (MAS) stations while the thinnest crust (around 18 km) is found at stations Rio Carpintero (RCC) and Guantanamo Bay (GTBY), in the southeastern of Cuba; this result is in agreement with the southward gradual thinning of the crust revealed by previous studies. The inversion shows a crystalline crust with S-wave velocity between 2.9 km/s and 3.9 km/s and at the crust-mantle transition zone the shear wave velocity varies from 3.9 km/s and 4.3 km/s. The lithospheric thickness varies from 74 km, in the youngest lithosphere, to 200 km in the middle of the Cuban island. Evidences of a subducted slab possibly belonging to the Caribbean plate are present below the stations Las Mercedes (LMG), RCC and GTBY and a thicker slab is present below the SOR station. (author)

  17. Modeling blast waves, gas and particles dispersion in urban and hilly ground areas

    International Nuclear Information System (INIS)

    Hank, S.; Saurel, R.; Le Metayer, O.; Lapebie, E.

    2014-01-01

    The numerical simulation of shock and blast waves as well as particles dispersion in highly heterogeneous media such as cities, urban places, industrial plants and part of countries is addressed. Examples of phenomena under study are chemical gas products dispersion from damaged vessels, gas dispersion in urban places under explosion conditions, shock wave propagation in urban environment. A three-dimensional simulation multiphase flow code (HI2LO) is developed in this aim. To simplify the consideration of complex geometries, a heterogeneous discrete formulation is developed. When dealing with large scale domains, such as countries, the topography is considered with the help of elevation data. Meteorological conditions are also considered, in particular regarding complex temperature and wind profiles. Heat and mass transfers on sub-scale objects, such as buildings, trees and other obstacles are considered as well. Particles motion is addressed through a new turbulence model involving a single parameter to describe accurately plumes. Validations against experiments in basic situations are presented as well as examples of industrial and environmental computations. (authors)

  18. Coupled hydromagnetic wave excitation and ion acceleration upstream of the earth's bow shock

    International Nuclear Information System (INIS)

    Lee, M.A.

    1982-01-01

    A self-consistent theory is presented for the excitation of hydromagnetic waves and the acceleration of diffuse ions upstream of the earth's bow shock in the quasi-equilibrium that results when the solar wind velocity and the interplanetary magnetic field are nearly parallel. For the waves the quasi-equilibrium results from a balance between excitation by the ions, which stream relative to the solar wind plasma, and convective loss to the magnetosheath. For the diffuse ions the quasi-equilibrium results from a balance between injection at the shock front, confinement to the foreshock by pitch angle scattering on the waves, acceleration by compression at the shock front, loss to the magnetosheath, loss due to escape upstream of the foreshock, and loss via diffusion perpendicular to the average magnetic field onto field lines that do not connect to the shock front. Diffusion equations describing the ion transport and wave kinetic equations describing the hydromagnetic wave transport are solved self-consistently to yield analytical expressions for the differential wave intensity spectrum as a function of frequency and distance from the bow shock z and for the ion omnidirectional distribution functions and anisotropies as functions of energy and z, In quantitative agreement with observations, the theory predicts (1) exponential spectra at the bow shock in energy per charge, (2) a decrease in intensity and hardening of the ion spectra with increasing z, (3) a 30-keV proton anisotropy parallel to z increasing from -0.28 at the bow shock to +0.51 as z→infinity (4) a linearly polarized wave intensity spectrum with a minimum at approx.6 x 10 -3 Hz and a maximum at approx.2--3 x 10 -2 Hz, (5) a decrease in the wave intensity spectrum with increasing z, (6) a total energy density in protons with energies >15 keV about eight times that in the hydromagnetic waves

  19. Ion Bernstein wave heating in a multi-component plasma

    International Nuclear Information System (INIS)

    Puri, S.

    1980-10-01

    Conditions for the coupling and absorption of Gross-Bernstein ion-cyclotron waves in a multi-component plasma are examined. Two cases are distinguished depending upon whether, the antenna initially launches, (i) the quasi-torsional slow electromagnetic wave with azimuthal magnetic field (TM) polarization, or (ii) the quasi-compressional fast wave with the electric field oriented azimuthally (TE). Analytic expressions for the plasma surface impedance are derived taking into account the pertinent warm plasma modifications near the vacuum-plasma interface. Antenna configurations capable of efficient coupling of the radio frequency energy to these modes are studied. A method for simulating waveguide like launching using transmission lines is pointed out. It is found that impurity concentrations exceeding a few parts in a thousand are capable of competing with the bulk ions in the energy absorption processes; this could lead to energy deposition near the plasma edge. Measures for avoiding edge heating problems by a careful choice of parameters e.g. restricting the heating frequency to the fundamental ion gyrofrequency are outlined. Equal care is to be exercised in limiting the nsub(z) spectrum to low discrete values in order to avoid the potentially dangerous problem of runaway electron heating. (orig.)

  20. Elastic wave from fast heavy ion irradiation on solids

    CERN Document Server

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

    2002-01-01

    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 sub 2 O sub 3), fused silica (SiO sub 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...

  1. Electron Acoustic Waves in Pure Ion Plasmas

    Science.gov (United States)

    Anderegg, F.; Affolter, M.; Driscoll, C. F.; O'Neil, T. M.; Valentini, F.

    2012-10-01

    Electron Acoustic Waves (EAWs) are the low-frequency branch of near-linear Langmuir (plasma) waves: the frequency is such that the complex dielectric function (Dr, Di) has Dr= 0; and ``flattening'' of f(v) near the wave phase velocity vph gives Di=0 and eliminates Landau damping. Here, we observe standing axisymmetric EAWs in a pure ion column.footnotetextF. Anderegg, et al., Phys. Rev. Lett. 102, 095001 (2009). At low excitation amplitudes, the EAWs have vph˜1.4 v, in close agreement with near-linear theory. At moderate excitation strengths, EAW waves are observed over a range of frequencies, with 1.3 v vphvph.footnotetextF. Valentini et al., arXiv:1206.3500v1. Large amplitude EAWs have strong phase-locked harmonic content, and experiments will be compared to same-geometry simulations, and to simulations of KEENfootnotetextB. Afeyan et al., Proc. Inertial Fusion Sci. and Applications 2003, A.N.S. Monterey (2004), p. 213. waves in HEDLP geometries.

  2. Obliquely propagating cnoidal waves in a magnetized dusty plasma with variable dust charge

    International Nuclear Information System (INIS)

    Yadav, L. L.; Sayal, V. K.

    2009-01-01

    We have studied obliquely propagating dust-acoustic nonlinear periodic waves, namely, dust-acoustic cnoidal waves, in a magnetized dusty plasma consisting of electrons, ions, and dust grains with variable dust charge. Using reductive perturbation method and appropriate boundary conditions for nonlinear periodic waves, we have derived Korteweg-de Vries (KdV) equation for the plasma. It is found that the contribution to the dispersion due to the deviation from plasma approximation is dominant for small angles of obliqueness, while for large angles of obliqueness, the dispersion due to magnetic force becomes important. The cnoidal wave solution of the KdV equation is obtained. It is found that the frequency of the cnoidal wave depends on its amplitude. The effects of the magnetic field, the angle of obliqueness, the density of electrons, the dust-charge variation and the ion-temperature on the characteristics of the dust-acoustic cnoidal wave are also discussed. It is found that in the limiting case the cnoidal wave solution reduces to dust-acoustic soliton solution.

  3. Dust ion-acoustic shock waves in magnetized pair-ion plasma with kappa distributed electrons

    Science.gov (United States)

    Kaur, B.; Singh, M.; Saini, N. S.

    2018-01-01

    We have performed a theoretical and numerical analysis of the three dimensional dynamics of nonlinear dust ion-acoustic shock waves (DIASWs) in a magnetized plasma, consisting of positive and negative ion fluids, kappa distributed electrons, immobile dust particulates along with positive and negative ion kinematic viscosity. By employing the reductive perturbation technique, we have derived the nonlinear Zakharov-Kuznetsov-Burgers (ZKB) equation, in which the nonlinear forces are balanced by dissipative forces (associated with kinematic viscosity). It is observed that the characteristics of DIASWs are significantly affected by superthermality of electrons, magnetic field strength, direction cosines, dust concentration, positive to negative ions mass ratio and viscosity of positive and negative ions.

  4. The nonlinear dustgrain-charging on large amplitude electrostatic waves in a dusty plasma with trapped ions

    Directory of Open Access Journals (Sweden)

    Y.-N. Nejoh

    1998-01-01

    Full Text Available The nonlinear dustgrain-charging and the influence of the ion density and temperature on electrostatic waves in a dusty plasma having trapped ions are investigated by numerical calculation. This work is the first approach to the effect of trapped ions in dusty plasmas. The nonlinear variation of the dust-charge is examined, and it is shown that the characteristics of the dustcharge number sensitively depend on the plasma potential, Mach number, dust mass-to-charge ratio, trapped ion density and temperature. The fast and slow wave modes are shown in this system. An increase of the ion temperature decreases the dust-charging rate and the propagation speed of ion waves. It is found that the existence of electrostatic ion waves sensitively depends on the ion to electron density ratio. New findings of the variable-charge dust grain particles, ion density and temperature in a dusty plasma with trapped ions are predicted.

  5. Relativistic invariance of dispersion-relations and their associated wave-operators and Green-functions

    International Nuclear Information System (INIS)

    Censor, Dan

    2010-01-01

    Identifying invariance properties helps in simplifying calculations and consolidating concepts. Presently the Special Relativistic invariance of dispersion relations and their associated scalar wave operators is investigated for general dispersive homogeneous linear media. Invariance properties of the four-dimensional Fourier-transform integrals is demonstrated, from which the invariance of the scalar Green-function is inferred. Dispersion relations and the associated group velocities feature in Hamiltonian ray tracing theory. The derivation of group velocities for moving media from the dispersion relation for these media at rest is discussed. It is verified that the group velocity concept satisfies the relativistic velocity-addition formula. In this respect it is considered to be 'real', i.e., substantial, physically measurable, and not merely a mathematical artifact. Conversely, if we assume the group velocity to be substantial, it follows that the dispersion relation must be a relativistic invariant. (orig.)

  6. Wavelength dispersive μPIXE setup for the ion microprobe

    Energy Technology Data Exchange (ETDEWEB)

    Fazinić, S., E-mail: stjepko.fazinic@irb.hr [Laboratory for Ion Beam Interactions, Division of Experimental Physics, Rudjer Bošković Institute, Bijenicka cesta 54, 10000 Zagreb (Croatia); Božičević Mihalić, I.; Tadić, T.; Cosic, D.; Jakšić, M. [Laboratory for Ion Beam Interactions, Division of Experimental Physics, Rudjer Bošković Institute, Bijenicka cesta 54, 10000 Zagreb (Croatia); Mudronja, D. [Croatian Conservation Institute, Grškovićeva 23, 10000 Zagreb (Croatia)

    2015-11-15

    We have developed a small wavelength dispersive X-ray spectrometer to explore the possibility of performing chemical speciation on microscopic samples utilizing focused ion beams available at the Rudjer Boskovic Institute ion microprobe. Although PIXE spectra are in principle chemically invariant, small influence of chemical effects could be observed even with Si(Li) or SDD detectors. Such chemical effects can be clearly seen with high resolution crystal X-ray spectrometers having energy resolution of several eV. A dedicated vacuum chamber, housing the diffraction crystal, sample holder and CCD X-ray detector, was constructed and positioned behind the main ion microprobe vacuum chamber. Here we will briefly describe the spectrometer, and illustrate its capabilities on measured K X-ray spectra of selected sulfur compounds. We will also demonstrate its abilities to resolve K and M X-ray lines irresolvable by solid state ED detectors usually used in PIXE.

  7. Charging-delay induced dust acoustic collisionless shock wave: Roles of negative ions

    International Nuclear Information System (INIS)

    Ghosh, Samiran; Bharuthram, R.; Khan, Manoranjan; Gupta, M. R.

    2006-01-01

    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)

  8. Effects of high power ion Bernstein waves on a tokamak plasma

    International Nuclear Information System (INIS)

    Ono, M.; Beiersdorfer, P.; Bell, R.

    1987-04-01

    Ion Bernstein wave heating (IBWH) has been investigated on PLT with up to 650 kW of rf power coupled to the plasma, exceeding the ohmic power of 550 kW. Plasma antenna loading of 2 Ω has been observed, resulting in 80 to 90% of the rf power being coupled to the plasma. An ion heating efficiency of ΔT/sub i/(0)n/sub e//P/sub rf/ = 6 x 10 13 eV cm -3 /kW, without high energy tail ions, has been observed up to the maximum rf power. The deuterium particle confinement during high power IBWH increases significantly (as much as 300%). Associated with it, a longer injected impurity confinement time, reduced drift wave turbulence activity, frequency shifts of drfit wave turbulence, and development of a large negative edge potential were observed. The energy confinement time, however, shows some degradation from the ohmic value, which can be attributed to the enhanced radiation loss observed during IBWH. The ion heating and energy confinement time are relatively independent of plasma current

  9. Effects of dust size distribution on dust negative ion acoustic solitary waves in a magnetized dusty plasma

    International Nuclear Information System (INIS)

    Ma, Yi-Rong; Qi, Xin; Sun, Jian-An; Duan, Wen-Shan; Yang, Lei

    2013-01-01

    Dust negative ion acoustic solitary waves in a magnetized multi-ion dusty plasma containing hot isothermal electron, ions (light positive ions and heavy negative ions) and extremely massive charge fluctuating dust grains are investigated by employing the reductive perturbation method. How the dust size distribution affect the height and the thickness of the nonlinear solitary wave are given. It is noted that the characteristic of the solitary waves are different with the different dust size distribution. The magnitude of the external magnetic field also affects the solitary wave form

  10. Ion temperature in plasmas with intrinsic Alfven waves

    International Nuclear Information System (INIS)

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

    2014-01-01

    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

  11. Second harmonic ion cylotron resonance heating by the fast magnetosonic wave on the PLT tokamak

    International Nuclear Information System (INIS)

    Thompson, H.R. Jr.

    1984-01-01

    Second harmonic ion cyclotron resonance heating by the fast magnetosonic wave, and the propagation of the fast wave from the fundamental of the ion cyclotron frequency to its second harmonic was investigated in a hydrogen plasma on the PLT tokamak. The theory of fast magnetosonic wave propagation was extended to include the effects of density gradients, plasma current, and impurity ion species. The damping of the fast wave at the second harmonic is calculated, where the theory has been extended to include the full radial dependence of the fast wave fields. Power deposition profiles and eigenmode Q's are calculated using this theory. The effects of the interaction between the ion Bernstein wave and the fast magnetosonic wave are calculated, and enhanced fast wave damping is predicted. The antenna loading is calculated including the effects of overlap of the fast wave eigenmodes. During the second harmonic heating experiments, the antenna loading was characterized as a function of the plasma parameters, and efficient coupling of the RF power to the plasma at high density was observed. At very low densities, fast wave eigenmodes were identified on PLT, and their Q's are measured. Eigenmodes with different toroidal directions of propagation were observed to exhibit large splitting in density due to the plasma current. Efficient bulk heating, with centrally peaked profiles, is observed at the second harmonic, and a tail, which decreases monotonically with energy, is observed on the ion distribution

  12. Phase dispersion of Raman and Rayleigh-enhanced four-wave mixings in femtosecond polarization beats

    International Nuclear Information System (INIS)

    Yan, Zhao; Zhi-Qiang, Nie; Chang-Biao, Li; Yan-Peng, Zhang; Chen-Li, Gan; Huai-Bin, Zheng; Yuan-Yuan, Li; Ke-Qing, Lu

    2009-01-01

    Based on color-locking noisy field correlation in three Markovian stochastic models, phase dispersions of the Raman- and Rayleigh-enhanced four-wave mixing (FWM) have been investigated. The phase dispersions are modified by both linewidth and time delay for negative time delay, but only by linewidth for positive time delay. Moreover, the results under narrowband condition are close to the nonmodified nonlinear dispersion and absorption of the material. Homodyne and heterodyne detections of the Raman, the Rayleigh and the mixing femtosecond difference-frequency polarization beats have also been investigated, separately

  13. Structure investigation of metal ions clustering in dehydrated gel using x-ray anomalous dispersion effect

    CERN Document Server

    Soejima, Y; Sugiyama, M; Annaka, M; Nakamura, A; Hiramatsu, N; Hara, K

    2003-01-01

    The structure of copper ion clusters in dehydrated N-isopropylacrylamide/sodium acrylate (NIPA/SA) gel has been studied by means of small angle X-ray scattering (SAXS) method. In order to distinguish the intensity scattered by Cu ions, the X-ray anomalous dispersion effect around the Cu K absorption edge has been coupled with SAXS. It is found that the dispersion effect dependent on the incident X-ray energy is remarkable only at the momentum transfer q = 0.031 A sup - sup 1 , where a SAXS peak is observed. The results indicate that copper ions form clusters in the dehydrated gel, and that the mean size of clusters is the same as that of SA clusters produced by microphase separation. It is therefore naturally presumed that copper ions are adsorbed into the SA molecules. On the basis of the presumption, a mechanism is proposed for microphase-separation and clustering of Cu ions.

  14. Non-planar ion-acoustic solitary waves and their head-on collision in a plasma with nonthermal electrons and warm adiabatic ions

    Energy Technology Data Exchange (ETDEWEB)

    Han Jiuning; He Yonglin; Chen Yan; Zhang Kezhi; Ma Baohong [College of Physics and Electromechanical Engineering, Hexi University, Zhangye 734000 (China)

    2013-01-15

    By using the model of Cairns et al.[Geophys. Rev. Lett. 22, 2709 (1995)], the head-on collision of cylindrical/spherical ion-acoustic solitary waves in an unmagnetized non-planar plasma consisting of warm adiabatic ions and nonthermally distributed electrons is investigated. The extended Poincare-Lighthill-Kuo perturbation method is used to derive the modified Korteweg-de Vries equations for ion-acoustic solitary waves in this plasma system. The effects of the plasma geometry m, the ion to electron temperature ratio {sigma}, and the nonthermality of the electron distribution {alpha} on the interaction of the colliding solitary waves are studied. It is found that the plasma geometries have a big impact on the phase shifts of solitary waves. Also it is important to note that the phase shifts induced by the collision of compressive and rarefactive solitary waves are very different. We point out that this study is useful to the investigations about the observations of electrostatic solitary structures in astrophysical as well as in experimental plasmas with nonthermal energetic electrons.

  15. Stabilization of ion temperature gradient driven modes by lower hybrid wave in a tokamak

    International Nuclear Information System (INIS)

    Kuley, Animesh; Tripathi, V. K.

    2009-01-01

    A gyrokinetic formalism has been developed to study lower hybrid wave stabilization of ion temperature gradient driven modes, responsible for anomalous ion transport in the inner region of tokamak. The parametric coupling between lower hybrid and drift waves produce lower hybrid sideband waves. The pump and the sidebands exert a ponderomotive force on electrons, modifying the eigenfrequency of the drift wave and influencing the growth rate. The longer wavelength drift waves are destabilized by the lower hybrid wave while the shorter wavelengths are suppressed. The requiste lower hybrid power is in the range of ∼900 kW at 4.6 GHz.

  16. Effects of vortex-like and non-thermal ion distributions on non-linear dust-acoustic waves

    International Nuclear Information System (INIS)

    Mamun, A.A.; Cairns, R.A.; Shukla, P.K.

    1996-01-01

    The effects of vortex-like and non-thermal ion distributions are incorporated in the study of nonlinear dust-acoustic waves in an unmagnetized dusty plasma. It is found that owing to the departure from the Boltzmann ion distribution to a vortex-like phase space distribution, the dynamics of small but finite amplitude dust-acoustic waves is governed by a modified Kortweg endash de Vries equation. The latter admits a stationary dust-acoustic solitary wave solution, which has larger amplitude, smaller width, and higher propagation velocity than that involving adiabatic ions. On the other hand, consideration of a non-thermal ion distribution provides the possibility of coexistence of large amplitude rarefactive as well as compressive dust-acoustic solitary waves, whereas these structures appear independently when the wave amplitudes become infinitely small. The present investigation should help us to understand the salient features of the non-linear dust-acoustic waves that have been observed in a recent numerical simulation study. copyright 1996 American Institute of Physics

  17. Ion sense of polarization of the electromagnetic wave field in the electron whistler frequency band

    Directory of Open Access Journals (Sweden)

    B. Lundin

    Full Text Available It is shown that the left-hand (or ion-type sense of polarization can appear in the field interference pattern of two plane electron whistler waves. Moreover, it is demonstrated that the ion-type polarized wave electric fields can be accompanied by the presence at the same observation point of electron-type polarized wave magnetic fields. The registration of ion-type polarized fields with frequencies between the highest ion gyrofrequency and the electron gyrofrequency in a cold, overdense plasma is a sufficient indication for the existence of an interference wave pattern, which can typically occur near artificial or natural reflecting magnetospheric plasma regions, inside waveguides (as in helicon discharges, for example, in fields resonantly emitted by beams of charged particles or, in principle, in some self-sustained, nonlinear wave field structures. A comparison with the conventional spectral matrix data processing approach is also presented in order to facilitate the calculations of the analyzed polarization parameters.

    Key words. Ionosphere (wave propagation Radio science (waves in plasma Space plasma physics (general or miscellaneous

  18. Ion sense of polarization of the electromagnetic wave field in the electron whistler frequency band

    Directory of Open Access Journals (Sweden)

    B. Lundin

    2002-08-01

    Full Text Available It is shown that the left-hand (or ion-type sense of polarization can appear in the field interference pattern of two plane electron whistler waves. Moreover, it is demonstrated that the ion-type polarized wave electric fields can be accompanied by the presence at the same observation point of electron-type polarized wave magnetic fields. The registration of ion-type polarized fields with frequencies between the highest ion gyrofrequency and the electron gyrofrequency in a cold, overdense plasma is a sufficient indication for the existence of an interference wave pattern, which can typically occur near artificial or natural reflecting magnetospheric plasma regions, inside waveguides (as in helicon discharges, for example, in fields resonantly emitted by beams of charged particles or, in principle, in some self-sustained, nonlinear wave field structures. A comparison with the conventional spectral matrix data processing approach is also presented in order to facilitate the calculations of the analyzed polarization parameters.Key words. Ionosphere (wave propagation Radio science (waves in plasma Space plasma physics (general or miscellaneous

  19. Large amplitude solitary waves in a multicomponent plasma with negative ions

    International Nuclear Information System (INIS)

    Nakamura, Y.; Tsukabayashi, I.; Ludwig, G.O.; Ferreira, J.L.

    1987-09-01

    When the concentration of negative ions is larger than a critical value, a small compressive pulse evolves into a subsonic wave train and a large pulse develops into a solitary wave. The threshold amplitude and velocity of the solitary waves are measured and compared with predictions using the pseudopotential method. (author) [pt

  20. Dispersion of repolarization in canine ventricle and the electrocardiographic T wave: Tp-e interval does not reflect transmural dispersion

    NARCIS (Netherlands)

    Opthof, Tobias; Coronel, Ruben; Wilms-Schopman, Francien J. G.; Plotnikov, Alexei N.; Shlapakova, Iryna N.; Danilo, Peter; Rosen, Michael R.; Janse, Michiel J.

    2007-01-01

    BACKGROUND: The concept that the interval between the peak (T(peak)) and the end (T(end)) of the T wave (T(p-e)) is a measure of transmural dispersion of repolarization time is widely accepted but has not been tested rigorously by transmural mapping of the intact heart. OBJECTIVES: The purpose of

  1. Fully nonlinear ion-acoustic solitary waves in a plasma with positive-negative ions and nonthermal electrons

    International Nuclear Information System (INIS)

    Sabry, R.; Shukla, P. K.; Moslem, W. M.

    2009-01-01

    Properties of fully nonlinear ion-acoustic solitary waves in a plasma with positive-negative ions and nonthermal electrons are investigated. For this purpose, the hydrodynamic equations for the positive-negative ions, nonthermal electron density distribution, and the Poisson equation are used to derive the energy integral equation with a new Sagdeev potential. The latter is analyzed to examine the existence regions of the solitary pulses. It is found that the solitary excitations strongly depend on the mass and density ratios of the positive and negative ions as well as the nonthermal electron parameter. Numerical solution of the energy integral equation clears that both positive and negative potentials exist together. It is found that faster solitary pulses are taller and narrower. Furthermore, increasing the electron nonthermality parameter (negative-to-positive ions density ratio) decreases (increases) the localized excitation amplitude but increases (decreases) the pulse width. The present model is used to investigate the solitary excitations in the (H + ,O 2 - ) and (H + ,H - ) plasmas, where they are presented in the D- and F-regions of the Earth's ionosphere. This investigation should be helpful in understanding the salient features of the fully nonlinear ion-acoustic solitary waves in space and in laboratory plasmas where two distinct groups of ions and non-Boltzmann distributed electrons are present.

  2. Modulational instability of the obliquely modulated ion acoustic waves in a warm ion plasma

    International Nuclear Information System (INIS)

    Saxena, M.K.; Arora, A.K.; Sharma, S.R.

    1981-01-01

    Using KBM. perturbation technique, it is shown that the modulationally unstable domain in the (kappa - phi) plane for the obliquely modulated ion acoustic waves is appreciably modified due to the finite ion temperature. It is also shown that in a collisionless plasma having small TAUsub(i)/TAUsub(e) ( 0 approximately 0.1) may exceed the Landau damping rate provided the modulation is sufficiently oblique. (author)

  3. Interventricular dispersion in repolarization causes bifid T waves in dogs with dofetilide-induced long QT syndrome

    NARCIS (Netherlands)

    Meijborg, Veronique M F; Chauveau, Samuel; Janse, Michiel J; Anyukhovsky, Evgeny P; Danilo, Peter R; Rosen, Michael R; Opthof, Tobias; Coronel, Ruben

    BACKGROUND: Long QT2 (LQT2) syndrome is characterized by bifid (or notched) T waves, whose mechanism is not understood. OBJECTIVE: The purpose of this study was to test whether increased interventricular dispersion of repolarization induces bifid T waves. METHODS: We simultaneously recorded surface

  4. Electromagnetic Ion Cyclotron Waves Detected by Kaguya and Geotail in the Earth's Magnetotail

    Science.gov (United States)

    Nakagawa, Tomoko; Nishino, Masaki N.; Tsunakawa, Hideo; Takahashi, Futoshi; Shibuya, Hidetoshi; Shimizu, Hisayoshi; Matsushima, Masaki; Saito, Yoshifumi

    2018-02-01

    Narrowband electromagnetic ion cyclotron waves first discovered by the Apollo 15 and 16 Lunar Surface Magnetometers were surveyed in the magnetic field data obtained by the Kaguya satellite at an altitude of ˜100 km above the Moon in the tail lobe and plasma sheet boundary layer of the Earth's magnetosphere. The frequencies of the waves were typically 0.7 times the local proton cyclotron frequency, and 75% of the waves were left hand polarized with respect to the background magnetic field. They had a significant compressional component and comprised several discrete packets. They were detected on the dayside, nightside, and above the terminator of the Moon, irrespective of the lunar magnetic anomaly, or the magnetic connection to the lunar surface. The waves with the same characteristics were detected by Geotail in the absence of the Moon in the magnetotail. The most likely energy source of the electromagnetic ion cyclotron waves is the ring beam ions in the plasma sheet boundary layer.

  5. Broadband light generation at ~1300 nm through spectrally recoiled solitons and dispersive waves

    DEFF Research Database (Denmark)

    Falk, Peter Andreas; Frosz, Michael Henoch; Bang, Ole

    2008-01-01

    We experimentally study the generation of broadband light at ~1300 nm from an 810 nm Ti:sapphire femtosecond pump laser. We use two photonic crystal fibers with a second infrared zero-dispersion wavelength (λZ2) and compare the efficiency of two schemes: in one fiber λZ2=1400 nm and the light...... at 1300 nm is composed of spectrally recoiled solitons; in the other fiber λZ2=1200 nm and the light at 1300 nm is composed of dispersive waves....

  6. Dispersion-Flattened Composite Highly Nonlinear Fibre Optimised for Broadband Pulsed Four-Wave Mixing

    DEFF Research Database (Denmark)

    Lillieholm, Mads; Galili, Michael; Oxenløwe, Leif Katsuo

    2016-01-01

    We present a segmented composite HNLF optimised for mitigation of dispersion-fluctuation impairments for broadband pulsed four-wave mixing. The HNLF-segmentation allows for pulsed FWMprocessing of a 13-nm wide input WDM-signal with -4.6-dB conversion efficiency...

  7. Spin-Wave Dispersion and Sublattice Magnetization in NiCl_2

    DEFF Research Database (Denmark)

    Lindgård, Per-Anker; Birgeneau, R. J.; Als-Nielsen, Jens Aage

    1975-01-01

    temperature dependence on the sublattice magnetization, gap energy and specific heat. The authors report an inelastic neutron scattering study of the spin waves both at low temperatures and, for selected q-vectors, for temperatures up to TN=52.3K. The sublattice magnetization has been measured from 1.5K to TN......-dependent dispersion relations (together with the sublattice magnetization) and the gap energy up to approximately 0.4 TN are properly predicted....

  8. Tunable spin waves in diluted magnetic semiconductor nanoribbon

    Science.gov (United States)

    Lyu, Pin; Zhang, Jun-Yi

    2018-01-01

    The spin wave excitation spectrum in diluted magnetic semiconductor (DMS) nanoribbons was calculated by taking account of the quantum confinement effect of carriers and spin waves. By introducing the boundary condition for the spin waves, we derived the spin wave dispersion using the path-integral formulation and Green's function method. It was shown that the spin wave excitation spectrum is discrete due to the confinement effect and strongly dependent on the carrier density, the magnetic ion density, and the width of the nanoribbon. When the width of the nanoribbon is beyond the typical nanoscales, the size effect on the excitation energies of the spin waves disappears in our calculation, which is in qualitative agreement with no obvious size effect observed in the as-made nanodevices of (Ga,Mn)As in this size regime. Our results provide a potential way to control the spin waves in the DMS nanoribbon not only by the carrier density and the magnetic ion density but also by the nanostructure geometry.

  9. Wave Equation Inversion of Skeletonized SurfaceWaves

    KAUST Repository

    Zhang, Zhendong

    2015-08-19

    We present a surface-wave inversion method that inverts for the S-wave velocity from the Rayleigh dispersion curve for the fundamental-mode. We call this wave equation inversion of skeletonized surface waves because the dispersion curve for the fundamental-mode Rayleigh wave is inverted using finite-difference solutions to the wave equation. The best match between the predicted and observed dispersion curves provides the optimal S-wave velocity model. Results with synthetic and field data illustrate the benefits and limitations of this method.

  10. Interventricular dispersion in repolarization causes bifid T waves in dogs with dofetilide-induced long QT syndrome

    NARCIS (Netherlands)

    Meijborg, Veronique M. F.; Chauveau, Samuel; Janse, Michiel J.; Anyukhovsky, Evgeny P.; Danilo, Peter R.; Rosen, Michael R.; Opthof, Tobias; Coronel, Ruben

    2015-01-01

    Long QT2 (LQT2) syndrome is characterized by bifid (or notched) T waves, whose mechanism is not understood. The purpose of this study was to test whether increased interventricular dispersion of repolarization induces bifid T waves. We simultaneously recorded surface ECG and unipolar electrograms at

  11. Free-electron lasers with magnetized ion-wiggler

    International Nuclear Information System (INIS)

    Mehdian, H.; Jafari, S.; Hasanbeigi, A.; Ebrahimi, F.

    2009-01-01

    Significant progress has been made using laser ionized channels to guide electron beams in the ion focus regime in a free-electron laser. Propagation of an electron beam in the ion focusing regime (IFR) allows the beam to propagate without expanding from space-charge repulsion. The ninth-degree polynomial dispersion relation for electromagnetic and space-charge waves is derived analytically by solving the electron momentum transfer and wave equations. The variation of resonant frequencies and peak growth rates with axial magnetic field strength has been demonstrated. Substantial enhancement in peak growth rate is obtained as the axial field frequency approaches the gyroresonance frequency.

  12. The influence of ion temperature on solitary waves in collisionless weak relativistic plasma

    International Nuclear Information System (INIS)

    Cerepaniuc, Adina

    2004-01-01

    Korteweg-de Vries equation is used to study the influence of the ion temperature, on the ion acoustic waves in the frame of collisionless plasma's weak relativistic effect. In the literature it is discussed the influence of ion temperature on the ion acoustic wave in a relativistic plasma for a ratio of the ion flow velocity to the light velocity between 0 and 1. In this paper, the dependence of the phase velocity on the relativistic effect for different values of the ratio of the ion temperature to the electron temperature is studied. In case of weak relativistic effect (ratio of the ion flow velocity to the light velocity is 10 -6 and the step of the representation is 10 -6 ) we noticed the occurrence of an antisoliton within soliton amplitude graphical representation as function of the relativistic effect and the temperature ratio. The novelty of this article consists in the fact that a much smaller interval is considered for velocity ratio (size) and we studied the influence of ion temperature on ion acoustic wave in a collisionless relativistic plasma. We performed the numerical calculation of equations and we plotted the phase velocity and the amplitude of soliton wave as a function of velocity ratio and the temperature ratio. We considered the step of velocity ratio variation equal with 10 -6 and the step of temperature ratio variation 10 -2 . The observation made in this paper refines the results of other authors who studied these equations for velocity ratio variation of 10 -1 . In herein chosen interval we observed new phenomena that were not noticed in the case of choosing larger intervals. (author)

  13. Heating and Acceleration of Solar Wind Ions by Turbulent Wave Spectrum in Inhomogeneous Expanding Plasma

    Science.gov (United States)

    Ofman, Leon; Ozak, Nataly; Vinas, Adolfo F.

    2016-01-01

    Near the Sun (plasma. The heating and the acceleration of the solar wind ions by turbulent wave spectrum in inhomogeneous plasma is studied using a 2.5D hybrid model. The hybrid model describes the kinetics of the ions, while the electrons are modeled as massless neutralizing fluid in an expanding box approach. Turbulent magnetic fluctuations dominated by power-law frequency spectra, which are evident from in-situ as well as remote sensing measurements, are used in our models. The effects of background density inhomogeneity across the magnetic field on the resonant ion heating are studied. The effect of super- Alfvenic ion drift on the ion heating is investigated. It is found that the turbulent wave spectrum of initially parallel propagating waves cascades to oblique modes, and leads to enhanced resonant ion heating due to the inhomogeneity. The acceleration of the solar wind ions is achieved by the parametric instability of large amplitude waves in the spectrum, and is also affected by the inhomogeneity. The results of the study provide the ion temperature anisotropy and drift velocity temporal evolution due to relaxation of the instability. The non-Maxwellian velocity distribution functions (VDFs) of the ions are modeled in the inhomogeneous solar wind plasma in the acceleration region close to the Sun.

  14. Dust ion acoustic solitary waves in a magnetized dusty plasma with anisotropic ion pressure

    International Nuclear Information System (INIS)

    Choi, Cheong Rim; Ryu, Chang-Mo; Lee, D.-Y.; Lee, Nam C.; Kim, Y.-H.

    2007-01-01

    The influence of anisotropic ion pressure on the dust ion acoustic solitary wave (DIASW) and the double layer (DL) obliquely propagating to a magnetic field are investigated by using the Sagdeev potential. The anisotropic ion pressure is defined by applying the Chew-Goldberger-Low (CGL) theory, p-perpendicular=p-perpendicular 0 n and p-parallel=p-parallel 0 n 3 , where n is the normalized ion density. The solutions of DIASWs and DLs obliquely propagating to an external magnetic field are obtained in the small amplitude limit. It is found that the perpendicular component of anisotropic ion pressure works differently from that of the parallel component on the DIASWs in a magnetized dusty plasma, deviating from a straight extension of the isotropic pressure effect

  15. Symmetries of the triple degenerate DNLS equations for weakly nonlinear dispersive MHD waves

    International Nuclear Information System (INIS)

    Webb, G. M.; Brio, M.; Zank, G. P.

    1996-01-01

    A formulation of Hamiltonian and Lagrangian variational principles, Lie point symmetries and conservation laws for the triple degenerate DNLS equations describing the propagation of weakly nonlinear dispersive MHD waves along the ambient magnetic field, in β∼1 plasmas is given. The equations describe the interaction of the Alfven and magnetoacoustic modes near the triple umbilic point, where the fast magnetosonic, slow magnetosonic and Alfven speeds coincide and a g 2 =V A 2 where a g is the gas sound speed and V A is the Alfven speed. A discussion is given of the travelling wave similarity solutions of the equations, which include solitary wave and periodic traveling waves. Strongly compressible solutions indicate the necessity for the insertion of shocks in the flow, whereas weakly compressible, near Alfvenic solutions resemble similar, shock free travelling wave solutions of the DNLS equation

  16. P-wave dispersion in endogenous and exogenous subclinical hyperthyroidism.

    Science.gov (United States)

    Gen, R; Akbay, E; Camsari, A; Ozcan, T

    2010-02-01

    The aim of this study was to measure maximum P wave duration (Pmax) and P wave dispersion (PWD), which can be indicators for the risk of paroxysmal atrial fibrillation when increased, and to reveal their relationship with thyroid hormone levels in patients with endogenous and exogenous subclinical hyperthyroidism. Seventy-one patients with sublinical thyrotoxicosis (34 endogenous, 37 exogenous) and 69 healthy individuals were enrolled in the study. Pmax and minimum P wave duration (Pmin) on electrocardiogram recordings were measured and PWD was calculated as Pmax-Pmin. Pmax (pendogenous subclinical hyperthyroidism compared with the control group. Pmax (pexogenous subclinical thyrotoxicosis compared with the control group. Pmax (p=0.710) and PWD (p=0.127) were not significantly different in patients with endogenous subclinical hyperthyroidism compared with exogenous subclinical hyperthyroid patients. Pmax and PWD negatively associated with TSH in endogenous and exogenous subclinical hyperthyroidism. In the present study, we observed that Pmax and PWD were longer in patients with endogenous and exogenous subclinical hyperthyroidism. Lack of a difference in Pmax and PWD between patients with endogenous and exogenous subclinical hyperthyroidism seems to support the idea that hormone levels rather than the etiology of thyrotoxicosis affect the heart.

  17. Dust acoustic solitary waves and double layers in a dusty plasma with two-temperature trapped ions

    International Nuclear Information System (INIS)

    El-Labany, S.K.; El-Taibany, W.F.; Mamun, A.A.; Moslem, Waleed M.

    2004-01-01

    The combined effects of trapped ion distribution, two-ion-temperature, dust charge fluctuation, and dust fluid temperature are incorporated in the study of nonlinear dust acoustic waves in an unmagnetized dusty plasma. It is found that, owing to the departure from the Boltzmann ion distribution to the trapped ion distribution, the dynamics of small but finite amplitude dust acoustic waves is governed by a modified Korteweg-de Vries equation. The latter admits a stationary dust acoustic solitary wave solution, which has stronger nonlinearity, smaller amplitude, wider width, and higher propagation velocity than that involving adiabatic ions. The effect of two-ion-temperature is found to provide the possibility for the coexistence of rarefactive and compressive dust acoustic solitary structures and double layers. Although the dust fluid temperature increases the amplitude of the small but finite amplitude solitary waves, the dust charge fluctuation does the opposite effect. The present investigation should help us to understand the salient features of the nonlinear dust acoustic waves that have been observed in a recent numerical simulation study

  18. Computer simulations on the nonlinear frequency shift and nonlinear modulation of ion-acoustic waves

    International Nuclear Information System (INIS)

    Ohsawa, Yukiharu; Kamimura, Tetsuo.

    1976-11-01

    The nonlinear behavior of ion-acoustic waves with rather short wave-length, k lambda sub(De) asymptotically equals 1, is investigated by computer sumulations. It is observed that the nonlinear frequency shift is negative and is proportional to square root of the initial wave amplitude when the amplitude is not too large. This proportionality breaks down and the frequency shift can become positive (for large Te/Ti), when (n tilde sub(i)/n 0 )sup(1/2)>0.25, where n tilde sub(i) is the ion density perturbation and n 0 the average plasma density. Nonlinear modulation of the wave-packet is clearly seen; however, modulational instability was not observed. The importance of the effects of trapped ions to these phenomena is emphasized. (auth.)

  19. 1D profiling using highly dispersive guided waves

    International Nuclear Information System (INIS)

    Volker, Arno; Zon, Tim van; Enthoven, Daniel; Verburg, Wesley

    2015-01-01

    Corrosion is one of the industries major issues regarding the integrity of assets. Currently inspections are conducted at regular intervals to ensure a sufficient integrity level of these assets. Cost reduction while maintaining a high level of reliability and safety of installations is a major challenge. There are many situations where the actual defect location is not accessible, e.g., a pipe support or a partially buried pipe. Guided wave tomography has been developed to reconstruct the wall thickness. In case of bottom of the line corrosion, i.e., a single corrosion pit, a simpler approach may be followed. Data is collected in a pit-catch configuration at the 12 o'clock position using highly dispersive guided waves. The phase spectrum is used to invert for a wall thickness profile in the circumferential direction, assuming a Gaussian defect profile. An EMAT sensor design has been made to measure at the 12 o'clock position of a pipe. The concept is evaluated on measured data, showing good sizing capabilities on a variety simple defect profiles

  20. Pierce-type dispersion relation for an intense relativistic electron beam interacting with a slow-wave structure

    International Nuclear Information System (INIS)

    Chen, C.

    1994-01-01

    A Pierce-type dispersion relation is derived for the interaction of an intense relativistic electron beam with a cylindrical slow-wave structure of arbitrary corrugation depth. It is shown that near a resonance, the Pierce parameter can be expressed in terms of the vacuum dispersion function and the beam current. The dispersion relation is valid in both the low-current (Compton) regime and the high-current (Raman) regime. The dispersion characteristics of the interaction, such as the linear instability growth rate and bandwidth, are analyzed for both regimes

  1. Resonant interactions between cometary ions and low frequency electromagnetic waves

    Science.gov (United States)

    Thorne, Richard M.; Tsurutani, Bruce T.

    1987-01-01

    The conditions for resonant wave amplification in a plasma with a ring-beam distribution which is intended to model pick-up ions in a cometary environment are investigated. The inclination between the interplanetary field and the solar wind is found to play a crucial role in governing both the resonant frequency and the growth rate of any unstable mode. It is suggested that the low-frequency MHD mode should experience the most rapid amplification for intermediate inclination. In the frame of the solar wind, such waves should propagate along the field in the direction upstream toward the sun with a phase speed lower than the beaming velocity of the pick-up ions. This mechanism may account for the presence of the interior MHD waves noted by satellites over a region surrounding comets Giacobini-Zinner and Halley.

  2. Tweaking the spin-wave dispersion and suppressing the incommensurate phase in LiNiPO4 by iron substitution

    DEFF Research Database (Denmark)

    Li, Jiying; Jensen, Thomas Bagger Stibius; Andersen, Niels Hessel

    2009-01-01

    ) indicates the instability of the Ising-type ground state that eventually evolves into the incommensurate phase as the temperature is raised. The pure LiNiPO4 system (x=0) undergoes a first-order magnetic phase transition from a long-range incommensurate phase to an antiferromagnetic (AFM) ground state at TN......Elastic and inelastic neutron-scattering studies of Li(Ni1−xFex)PO4 single crystals reveal anomalous spin-wave dispersions along the crystallographic direction parallel to the characteristic wave vector of the magnetic incommensurate phase. The anomalous spin-wave dispersion (magnetic soft mode......=20.8 K. At 20% Fe concentrations, although the AFM ground state is to a large extent preserved as that of the pure system, the phase transition is second order, and the incommensurate phase is completely suppressed. Analysis of the dispersion curves using a Heisenberg spin Hamiltonian that includes...

  3. Observation of refraction and convergence of ion acoustic waves in a plasma with a temperature gradient

    International Nuclear Information System (INIS)

    Nishida, Y.; Hirose, A.

    1977-01-01

    The refraction and convergence of ion acoustic waves are experimentally investigated in a magnetized plasma with an electron temperature gradient. When ion acoustic waves are launched parallel to the field lines the waves converge toward the interior of the plasma column where the electron temperature is lower, in good agreement with theoretical prediction. Wave interference is also observed. (author)

  4. Modification of ion-acoustic solitons on interaction with Langmuir waves

    International Nuclear Information System (INIS)

    Basovich, A.Ya.; Gromov, E.M.; Karpman, V.I.

    1981-01-01

    Variation of an ion-accoustic soliton under the effect of the Langmuir quasimonochromatic wave has been considered. Parameters of the soliton tail and variation of soliton velocity have been determined. It is shown that the soliton tail consists of two parts: averaged and oscillating. Density oscillations have a forced nature and are related to the modulation of striction force appearing during interference of waves incident and reflected from a soliton. Oscillations appear behind soliton when the wave runs after soliton and in front of soliton when soliton runs after wave [ru

  5. A Simple FDTD Algorithm for Simulating EM-Wave Propagation in General Dispersive Anisotropic Material

    KAUST Repository

    Al-Jabr, Ahmad Ali; Alsunaidi, Mohammad A.; Ng, Tien Khee; Ooi, Boon S.

    2013-01-01

    In this paper, an finite-difference time-domain (FDTD) algorithm for simulating propagation of EM waves in anisotropic material is presented. The algorithm is based on the auxiliary differential equation and the general polarization formulation. In anisotropic materials, electric fields are coupled and elements in the permittivity tensor are, in general, multiterm dispersive. The presented algorithm resolves the field coupling using a formulation based on electric polarizations. It also offers a simple procedure for the treatment of multiterm dispersion in the FDTD scheme. The algorithm is tested by simulating wave propagation in 1-D magnetized plasma showing excellent agreement with analytical solutions. Extension of the algorithm to multidimensional structures is straightforward. The presented algorithm is efficient and simple compared to other algorithms found in the literature. © 2012 IEEE.

  6. A Simple FDTD Algorithm for Simulating EM-Wave Propagation in General Dispersive Anisotropic Material

    KAUST Repository

    Al-Jabr, Ahmad Ali

    2013-03-01

    In this paper, an finite-difference time-domain (FDTD) algorithm for simulating propagation of EM waves in anisotropic material is presented. The algorithm is based on the auxiliary differential equation and the general polarization formulation. In anisotropic materials, electric fields are coupled and elements in the permittivity tensor are, in general, multiterm dispersive. The presented algorithm resolves the field coupling using a formulation based on electric polarizations. It also offers a simple procedure for the treatment of multiterm dispersion in the FDTD scheme. The algorithm is tested by simulating wave propagation in 1-D magnetized plasma showing excellent agreement with analytical solutions. Extension of the algorithm to multidimensional structures is straightforward. The presented algorithm is efficient and simple compared to other algorithms found in the literature. © 2012 IEEE.

  7. The Influence of Drift Gas Composition on the Separation Mechanism in Traveling Wave Ion Mobility Spectrometry: Insight from Electrodynamic Simulations.

    Science.gov (United States)

    May, Jody C; McLean, John A

    2003-06-01

    The influence of three different drift gases (helium, nitrogen, and argon) on the separation mechanism in traveling wave ion mobility spectrometry is explored through ion trajectory simulations which include considerations for ion diffusion based on kinetic theory and the electrodynamic traveling wave potential. The model developed for this work is an accurate depiction of a second-generation commercial traveling wave instrument. Three ion systems (cocaine, MDMA, and amphetamine) whose reduced mobility values have previously been measured in different drift gases are represented in the simulation model. The simulation results presented here provide a fundamental understanding of the separation mechanism in traveling wave, which is characterized by three regions of ion motion: (1) ions surfing on a single wave, (2) ions exhibiting intermittent roll-over onto subsequent waves, and (3) ions experiencing a steady state roll-over which repeats every few wave cycles. These regions of ion motion are accessed through changes in the gas pressure, wave amplitude, and wave velocity. Resolving power values extracted from simulated arrival times suggest that momentum transfer in helium gas is generally insufficient to access regions (2) and (3) where ion mobility separations occur. Ion mobility separations by traveling wave are predicted to be effectual for both nitrogen and argon, with slightly lower resolving power values observed for argon as a result of band-broadening due to collisional scattering. For the simulation conditions studied here, the resolving power in traveling wave plateaus between regions (2) and (3), with further increases in wave velocity contributing only minor improvements in separations.

  8. VOYAGER OBSERVATIONS OF MAGNETIC WAVES DUE TO NEWBORN INTERSTELLAR PICKUP IONS: 2–6 au

    International Nuclear Information System (INIS)

    Aggarwal, Poornima; Taylor, David K.; Smith, Charles W.; Joyce, Colin J.; Fisher, Meghan K.; Isenberg, Philip A.; Vasquez, Bernard J.; Schwadron, Nathan A.; Cannon, Bradford E.; Richardson, John D.

    2016-01-01

    We report observations by the Voyager 1 and 2 spacecraft of low-frequency magnetic waves excited by newborn interstellar pickup ions H + and He + during 1978–1979 when the spacecraft were in the range from 2 to 6.3 au. The waves have the expected association with the cyclotron frequency of the source ions, are left-hand polarized in the spacecraft frame, and have minimum variance directions that are quasi-parallel to the local mean magnetic field. There is one exception to this in that one wave event that is excited by pickup H + is right-hand polarized in the spacecraft frame, but similar exceptions have been reported by Cannon et al. and remain unexplained. We apply the theory of Lee and Ip that predicts the energy spectrum of the waves and then compare growth rates with turbulent cascade rates under the assumption that turbulence acts to destroy the enhanced wave activity and transport the associated energy to smaller scales where dissipation heats the background plasma. As with Cannon et al., we find that the ability to observe the waves depends on the ambient turbulence being weak when compared with growth rates, thereby allowing sustained wave growth. This analysis implies that the coupled processes of pitch-angle scattering and wave generation are continuously associated with newly ionized pickup ions, despite the fact that the waves themselves may not be directly observable. When waves are not observed, but wave excitation can be argued to be present, the wave energy is simply absorbed by the turbulence at a rate that prevents significant accumulation. In this way, the kinetic process of wave excitation by scattering of newborn ions continues to heat the plasma without producing observable wave energy. These findings support theoretical models that invoke efficient scattering of new pickup ions, leading to turbulent driving in the outer solar wind and in the IBEX ribbon beyond the heliopause.

  9. VOYAGER OBSERVATIONS OF MAGNETIC WAVES DUE TO NEWBORN INTERSTELLAR PICKUP IONS: 2–6 au

    Energy Technology Data Exchange (ETDEWEB)

    Aggarwal, Poornima [Electrical Engineering Department, Cooper Union, New York, NY 10003 (United States); Taylor, David K. [Rensselaer Polytechnic Institute, Troy, NH 12180 (United States); Smith, Charles W.; Joyce, Colin J.; Fisher, Meghan K.; Isenberg, Philip A.; Vasquez, Bernard J.; Schwadron, Nathan A. [Physics Department and Space Science Center, Institute for the Study of Earth, Oceans, and Space, University of New Hampshire, Durham, NH 03824 (United States); Cannon, Bradford E. [Physics Department, Florida State University, Tallahassee, FL 32306 (United States); Richardson, John D., E-mail: neema2000@gmail.com, E-mail: daves@orol.org, E-mail: Charles.Smith@unh.edu, E-mail: cjl46@wildcats.unh.edu, E-mail: mkl54@wildcats.unh.edu, E-mail: Phil.Isenberg@unh.edu, E-mail: Bernie.Vasquez@unh.edu, E-mail: N.Schwadron@unh.edu, E-mail: bc13h@my.fsu.edu, E-mail: jdr@space.mit.edu [Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, 37-655, Cambridge, MA 02139 (United States)

    2016-05-10

    We report observations by the Voyager 1 and 2 spacecraft of low-frequency magnetic waves excited by newborn interstellar pickup ions H{sup +} and He{sup +} during 1978–1979 when the spacecraft were in the range from 2 to 6.3 au. The waves have the expected association with the cyclotron frequency of the source ions, are left-hand polarized in the spacecraft frame, and have minimum variance directions that are quasi-parallel to the local mean magnetic field. There is one exception to this in that one wave event that is excited by pickup H{sup +} is right-hand polarized in the spacecraft frame, but similar exceptions have been reported by Cannon et al. and remain unexplained. We apply the theory of Lee and Ip that predicts the energy spectrum of the waves and then compare growth rates with turbulent cascade rates under the assumption that turbulence acts to destroy the enhanced wave activity and transport the associated energy to smaller scales where dissipation heats the background plasma. As with Cannon et al., we find that the ability to observe the waves depends on the ambient turbulence being weak when compared with growth rates, thereby allowing sustained wave growth. This analysis implies that the coupled processes of pitch-angle scattering and wave generation are continuously associated with newly ionized pickup ions, despite the fact that the waves themselves may not be directly observable. When waves are not observed, but wave excitation can be argued to be present, the wave energy is simply absorbed by the turbulence at a rate that prevents significant accumulation. In this way, the kinetic process of wave excitation by scattering of newborn ions continues to heat the plasma without producing observable wave energy. These findings support theoretical models that invoke efficient scattering of new pickup ions, leading to turbulent driving in the outer solar wind and in the IBEX ribbon beyond the heliopause.

  10. Wave Equation Inversion of Skeletonized SurfaceWaves

    KAUST Repository

    Zhang, Zhendong; Liu, Yike; Schuster, Gerard T.

    2015-01-01

    We present a surface-wave inversion method that inverts for the S-wave velocity from the Rayleigh dispersion curve for the fundamental-mode. We call this wave equation inversion of skeletonized surface waves because the dispersion curve

  11. Scaling relations for soliton compression and dispersive-wave generation in tapered optical fibers

    DEFF Research Database (Denmark)

    Lægsgaard, Jesper

    2018-01-01

    In this paper, scaling relations for soliton compression in tapered optical fibers are derived and discussed. The relations allow simple and semi-accurate estimates of the compression point and output noise level, which is useful, for example, for tunable dispersive-wave generation with an agile ...

  12. Shear wave crustal velocity model of the Western Bohemian Massif from Love wave phase velocity dispersion

    Czech Academy of Sciences Publication Activity Database

    Kolínský, Petr; Málek, Jiří; Brokešová, J.

    2011-01-01

    Roč. 15, č. 1 (2011), s. 81-104 ISSN 1383-4649 R&D Projects: GA AV ČR IAA300460602; GA AV ČR IAA300460705; GA ČR(CZ) GA205/06/1780 Institutional research plan: CEZ:AV0Z30460519 Keywords : love waves * phase velocity dispersion * frequency-time analysis Subject RIV: DC - Siesmology, Volcanology, Earth Structure Impact factor: 1.326, year: 2011 www.springerlink.com/content/w3149233l60111t1/

  13. High-frequency modulation of ion-acoustic waves.

    Science.gov (United States)

    Albright, N. W.

    1972-01-01

    A large amplitude, high-frequency electromagnetic oscillation is impressed on a nonrelativistic, collisionless plasma from an external source. The frequency is chosen to be far from the plasma frequency (in fact, lower). The resulting electron velocity distribution function strongly modifies the propagation of ion-acoustic waves parallel to the oscillating electric field. The complex frequency is calculated numerically.

  14. Nonlinear wave-particle interaction upstream from the Earth's bow shock

    Directory of Open Access Journals (Sweden)

    C. Mazelle

    2000-01-01

    Full Text Available Well-defined ring-like backstreaming ion distributions have been recently reported from observations made by the 3DP/PESA-High analyzer onboard the WIND spacecraft in the Earth's foreshock at large distances from the bow shock, which suggests a local production mechanism. The maximum phase space density for these distributions remains localized at a nearly constant pitch-angle value for a large number of gyroperiods while the shape of the distribution remains very steady. These distributions are also observed in association with quasi-monochromatic low frequency (~ 50 mHz waves with substantial amplitude (δB/B>0.2. The analysis of the magnetic field data has shown that the waves are propagating parallel to the background field in the right-hand mode. Parallel ion beams are also often observed in the same region before the observation of both the ring-like distributions and the waves. The waves appear in cyclotron resonance with the ion parallel beams. We investigate first the possibility that the ion beams could provide the free energy source for driving an ion/ion instability responsible for the ULF wave occurrence. For that, we solve the wave dispersion relation with the observed parameters. Second, we show that the ring-like distributions could then be produced by a coherent nonlinear wave-particle interaction. It tends to trap the ions into narrow cells in velocity space centered on a well-defined pitch-angle, directly related to the saturation wave amplitude in the analytical theory. The theoretical predictions are in good quantitative agreement with the observations

  15. Influence of Complete Coriolis Force on the Dispersion Relation of Ocean Internal-wave in a Background Currents Field

    Directory of Open Access Journals (Sweden)

    Liu Yongjun

    2015-01-01

    Full Text Available In this thesis, the influence of complete Coriolis force (the model includes both the vertical and horizontal components of Coriolis force on the dispersion relation of ocean internal-wave under background currents field are studied, it is important to the study of ocean internal waves in density-stratified ocean. We start from the control equation of sea water movement in the background of the non-traditional approximation, and the vertical velocity solution is derived where buoyancy frequency N(z gradually varies with the ocean depth z. The results show that the influence of complete Coriolis force on the dispersion relation of ocean internal-wave under background currents field is obvious, and these results provide strong evidence for the understanding of dynamic process of density stratified ocean internal waves.

  16. Ion-Bernstein wave mode conversion in hot tokamak plasmas

    International Nuclear Information System (INIS)

    Jaun, A.; Hellsten, T.; Chiu, S.C.

    1997-08-01

    Mode conversion at the second harmonic cyclotron resonance is studied in a toroidal plasma, showing how the ion-Bernstein wave can dramatically affect the power profile and partition among the species. The results obtained with the gyrokinetic toroidal PENN code in particular suggest that off-axis electron and second harmonic core ion heating should become important when the temperatures in JET reach 10 keV. (author) 1 fig., 11 refs

  17. Experimental observation of strong coupling effects on the dispersion of dust acoustic waves in a plasma

    Energy Technology Data Exchange (ETDEWEB)

    Bandyopadhyay, P. [Institute for Plasma Research, Bhat, Gandhinagar 382428 (India)], E-mail: pintu@ipr.res.in; Prasad, G.; Sen, A.; Kaw, P.K. [Institute for Plasma Research, Bhat, Gandhinagar 382428 (India)

    2007-09-03

    The dispersion properties of low frequency dust acoustic waves in the strong coupling regime are investigated experimentally in an argon plasma embedded with a mixture of kaolin and MnO{sub 2} dust particles. The neutral pressure is varied over a wide range to change the collisional properties of the dusty plasma. In the low collisional regime the turnover of the dispersion curve at higher wave numbers and the resultant region of {partial_derivative}{omega}/{partial_derivative}k<0 are identified as signatures of dust-dust correlations. In the high collisional regime dust neutral collisions produce a similar effect and prevent an unambiguous identification of strong coupling effects.

  18. Experimental observation of strong coupling effects on the dispersion of dust acoustic waves in a plasma

    International Nuclear Information System (INIS)

    Bandyopadhyay, P.; Prasad, G.; Sen, A.; Kaw, P.K.

    2007-01-01

    The dispersion properties of low frequency dust acoustic waves in the strong coupling regime are investigated experimentally in an argon plasma embedded with a mixture of kaolin and MnO 2 dust particles. The neutral pressure is varied over a wide range to change the collisional properties of the dusty plasma. In the low collisional regime the turnover of the dispersion curve at higher wave numbers and the resultant region of ∂ω/∂k<0 are identified as signatures of dust-dust correlations. In the high collisional regime dust neutral collisions produce a similar effect and prevent an unambiguous identification of strong coupling effects

  19. Experimental observation of strong coupling effects on the dispersion of dust acoustic waves in a plasma

    Science.gov (United States)

    Bandyopadhyay, P.; Prasad, G.; Sen, A.; Kaw, P. K.

    2007-09-01

    The dispersion properties of low frequency dust acoustic waves in the strong coupling regime are investigated experimentally in an argon plasma embedded with a mixture of kaolin and MnO2 dust particles. The neutral pressure is varied over a wide range to change the collisional properties of the dusty plasma. In the low collisional regime the turnover of the dispersion curve at higher wave numbers and the resultant region of ∂ω/∂k<0 are identified as signatures of dust dust correlations. In the high collisional regime dust neutral collisions produce a similar effect and prevent an unambiguous identification of strong coupling effects.

  20. Dust ion-acoustic solitary waves in a dusty plasma with nonextensive electrons

    Science.gov (United States)

    Bacha, Mustapha; Tribeche, Mouloud; Shukla, Padma Kant

    2012-05-01

    The dust-modified ion-acoustic waves of Shukla and Silin are revisited within the theoretical framework of the Tsallis statistical mechanics. Nonextensivity may originate from correlation or long-range plasma interactions. Interestingly, we find that owing to electron nonextensivity, dust ion-acoustic (DIA) solitary waves may exhibit either compression or rarefaction. Our analysis is then extended to include self-consistent dust charge fluctuation. In this connection, the correct nonextensive electron charging current is rederived. The Korteweg-de Vries equation, as well as the Korteweg-de Vries-Burgers equation, is obtained, making use of the reductive perturbation method. The DIA waves are then analyzed for parameters corresponding to space dusty plasma situations.

  1. Strong ion accelerating by collisionless magnetosonic shock wave propagating perpendicular to a magnetic field

    International Nuclear Information System (INIS)

    Ohsawa, Yukiharu.

    1984-12-01

    A 2-1/2 dimensional fully relativistic, fully electromagnetic particle code is used to study a time evolution of nonlinear magnetosonic pulse propagating in the direction perpendicular to a magnetic field. The pulse is excited by an instantaneous piston acceleration, and evolves totally self-consistently. Large amplitude pulse traps some ions and accelerates them parallel to the wave front. They are detrapped when their velocities become of the order of the sum of the ExB drift velocity and the wave phase velocity, where E is the electric field in the direction of wave propagation. The pulse develops into a quasi-shock wave in a collisionless plasma by a dissipation due to the resonant ion acceleration. Simple nonlinear wave theory for a cold plasma well describes the shock properties observed in the simulation except for the effects of resonant ions. In particular, magnitude of an electric potential across the shock region is derived analytically and is found to be in good agreement with our simulations. The potential jump is proportional to B 2 , and hence the ExB drift velocity of the trapped ions is proportional to B. (author)

  2. Rogue wave train generation in a metamaterial induced by cubic-quintic nonlinearities and second-order dispersion

    Science.gov (United States)

    Essama, Bedel Giscard Onana; Atangana, Jacques; Frederick, Biya Motto; Mokhtari, Bouchra; Eddeqaqi, Noureddine Cherkaoui; Kofane, Timoleon Crepin

    2014-09-01

    We investigate the behavior of the electromagnetic wave that propagates in a metamaterial for negative index regime. Second-order dispersion and cubic-quintic nonlinearities are taken into account. The behavior obtained for negative index regime is compared to that observed for absorption regime. The collective coordinates technique is used to characterize the light pulse intensity profile at some frequency ranges. Five frequency ranges have been pointed out. The perfect combination of second-order dispersion and cubic nonlinearity leads to a robust soliton at each frequency range for negative index regime. The soliton peak power progressively decreases for absorption regime. Further, this peak power also decreases with frequency. We show that absorption regime can induce rogue wave trains generation at a specific frequency range. However, this rogue wave trains generation is maintained when the quintic nonlinearity comes into play for negative index regime and amplified for absorption regime at a specific frequency range. It clearly appears that rogue wave behavior strongly depends on the frequency and the regime considered. Furthermore, the stability conditions of the electromagnetic wave have also been discussed at frequency ranges considered for both negative index and absorption regimes.

  3. Visible continuum pulses based on enhanced dispersive wave generation for endogenous fluorescence imaging.

    Science.gov (United States)

    Cui, Quan; Chen, Zhongyun; Liu, Qian; Zhang, Zhihong; Luo, Qingming; Fu, Ling

    2017-09-01

    In this study, we demonstrate endogenous fluorescence imaging using visible continuum pulses based on 100-fs Ti:sapphire oscillator and a nonlinear photonic crystal fiber. Broadband (500-700 nm) and high-power (150 mW) continuum pulses are generated through enhanced dispersive wave generation by pumping femtosecond pulses at the anomalous dispersion region near zero-dispersion wavelength of high-nonlinear photonic crystal fibers. We also minimize the continuum pulse width by determining the proper fiber length. The visible-wavelength two-photon microscopy produces NADH and tryptophan images of mice tissues simultaneously. Our 500-700 nm continuum pulses support extending nonlinear microscopy to visible wavelength range that is inaccessible to 100-fs Ti:sapphire oscillators and other applications requiring visible laser pulses.

  4. Full wave simulation of waves in ECRIS plasmas based on the finite element method

    Energy Technology Data Exchange (ETDEWEB)

    Torrisi, G. [INFN - Laboratori Nazionali del Sud, via S. Sofia 62, 95123, Catania, Italy and Università Mediterranea di Reggio Calabria, Dipartimento di Ingegneria dell' Informazione, delle Infrastrutture e dell' Energia Sostenibile (DIIES), Via Graziella, I (Italy); Mascali, D.; Neri, L.; Castro, G.; Patti, G.; Celona, L.; Gammino, S.; Ciavola, G. [INFN - Laboratori Nazionali del Sud, via S. Sofia 62, 95123, Catania (Italy); Di Donato, L. [Università degli Studi di Catania, Dipartimento di Ingegneria Elettrica Elettronica ed Informatica (DIEEI), Viale Andrea Doria 6, 95125 Catania (Italy); Sorbello, G. [INFN - Laboratori Nazionali del Sud, via S. Sofia 62, 95123, Catania, Italy and Università degli Studi di Catania, Dipartimento di Ingegneria Elettrica Elettronica ed Informatica (DIEEI), Viale Andrea Doria 6, 95125 Catania (Italy); Isernia, T. [Università Mediterranea di Reggio Calabria, Dipartimento di Ingegneria dell' Informazione, delle Infrastrutture e dell' Energia Sostenibile (DIIES), Via Graziella, I-89100 Reggio Calabria (Italy)

    2014-02-12

    This paper describes the modeling and the full wave numerical simulation of electromagnetic waves propagation and absorption in an anisotropic magnetized plasma filling the resonant cavity of an electron cyclotron resonance ion source (ECRIS). The model assumes inhomogeneous, dispersive and tensorial constitutive relations. Maxwell's equations are solved by the finite element method (FEM), using the COMSOL Multiphysics{sup ®} suite. All the relevant details have been considered in the model, including the non uniform external magnetostatic field used for plasma confinement, the local electron density profile resulting in the full-3D non uniform magnetized plasma complex dielectric tensor. The more accurate plasma simulations clearly show the importance of cavity effect on wave propagation and the effects of a resonant surface. These studies are the pillars for an improved ECRIS plasma modeling, that is mandatory to optimize the ion source output (beam intensity distribution and charge state, especially). Any new project concerning the advanced ECRIS design will take benefit by an adequate modeling of self-consistent wave absorption simulations.

  5. Ion acoustic solitary waves in a dusty plasma obliquely propagating to an external magnetic field

    International Nuclear Information System (INIS)

    Choi, Cheong Rim; Ryu, Chang-Mo; Lee, Nam C.; Lee, D.-Y.

    2005-01-01

    The nonlinear ion acoustic solitary wave in a magnetized dusty plasma, obliquely propagating to the embedding external magnetic field, is revisited. It is found that when the charge density of dust particles is high, the Sagdeev potential needs to be expanded up to δn 4 near n=1. In this case, it is shown that there could exist rarefactive ion acoustic solitary waves as well as the kink-type double layer solutions, in addition to the conventional hump-type ones found in the δn 3 expansion. The amplitude variations of ion acoustic solitary waves in a magnetized dusty plasma are also examined with respect to the change of the dust charge density and the wave directional angle

  6. Generation of ion-acoustic waves in an inductively coupled, low-pressure discharge lamp

    International Nuclear Information System (INIS)

    Camparo, J. C.; Klimcak, C. M.

    2006-01-01

    For a number of years it has been known that the alkali rf-discharge lamps used in atomic clocks can exhibit large amplitude intensity oscillations. These oscillations arise from ion-acoustic plasma waves and have typically been associated with erratic clock behavior. Though large amplitude ion-acoustic plasma waves are clearly deleterious for atomic clock operation, it does not follow that small amplitude oscillations have no utility. Here, we demonstrate two easily implemented methods for generating small amplitude ion-acoustic plasma waves in alkali rf-discharge lamps. Furthermore, we demonstrate that the frequency of these waves is proportional to the square root of the rf power driving the lamp and therefore that their examination can provide an easily accessible parameter for monitoring and controlling the lamp's plasma conditions. This has important consequences for precise timekeeping, since the atomic ground-state hyperfine transition, which is the heart of the atomic clock signal, can be significantly perturbed by changes in the lamp's output via the ac-Stark shift

  7. Bifurcation analysis for ion acoustic waves in a strongly coupled plasma including trapped electrons

    Science.gov (United States)

    El-Labany, S. K.; El-Taibany, W. F.; Atteya, A.

    2018-02-01

    The nonlinear ion acoustic wave propagation in a strongly coupled plasma composed of ions and trapped electrons has been investigated. The reductive perturbation method is employed to derive a modified Korteweg-de Vries-Burgers (mKdV-Burgers) equation. To solve this equation in case of dissipative system, the tangent hyperbolic method is used, and a shock wave solution is obtained. Numerical investigations show that, the ion acoustic waves are significantly modified by the effect of polarization force, the trapped electrons and the viscosity coefficients. Applying the bifurcation theory to the dynamical system of the derived mKdV-Burgers equation, the phase portraits of the traveling wave solutions of both of dissipative and non-dissipative systems are analyzed. The present results could be helpful for a better understanding of the waves nonlinear propagation in a strongly coupled plasma, which can be produced by photoionizing laser-cooled and trapped electrons [1], and also in neutron stars or white dwarfs interior.

  8. Observation of the dispersion of wedge waves propagating along cylinder wedge with different truncations by laser ultrasound technique

    Science.gov (United States)

    Jia, Jing; Zhang, Yu; Han, Qingbang; Jing, Xueping

    2017-10-01

    The research focuses on study the influence of truncations on the dispersion of wedge waves propagating along cylinder wedge with different truncations by using the laser ultrasound technique. The wedge waveguide models with different truncations were built by using finite element method (FEM). The dispersion curves were obtained by using 2D Fourier transformation method. Multiple mode wedge waves were observed, which was well agreed with the results estimated from Lagasse's empirical formula. We established cylinder wedge with radius of 3mm, 20° and 60°angle, with 0μm, 5μm, 10μm, 20μm, 30μm, 40μm, and 50μm truncations, respectively. It was found that non-ideal wedge tip caused abnormal dispersion of the mode of cylinder wedge, the modes of 20° cylinder wedge presents the characteristics of guide waves which propagating along hollow cylinder as the truncation increasing. Meanwhile, the modes of 60° cylinder wedge with truncations appears the characteristics of guide waves propagating along hollow cylinder, and its mode are observed clearly. The study can be used to evaluate and detect wedge structure.

  9. [A probability wave theory on the ion movement across cell membrane].

    Science.gov (United States)

    Zhang, Hui; Xu, Jiadong; Niu, Zhongqi

    2007-04-01

    The ionic quantity across the channel of the cell membrane decides the cell in a certain life state. The theory analysis that existed on the bio-effects of the electro-magnetic field (EMF) does not unveil the relationship between the EMF exerted on the cell and the ionic quantity across the cell membrane. Based on the cell construction, the existed theory analysis and the experimental results, an ionic probability wave theory is proposed in this paper to explain the biological window-effects of the electromagnetic wave. The theory regards the membrane channel as the periodic potential barrier and gives the physical view of the ion movement across cell-membrane. The theory revises the relationship between ion's energy in cell channel and the frequency exerted EMF. After the application of the concept of the wave function, the ionic probability across the cell membrane is given by the method of the quantum mechanics. The numerical results analyze the physical factors that influences the ion's movement across the cell membrane. These results show that the theory can explain the phenomenon of the biological window-effects.

  10. A model for the numerical simulations of ion cyclotron heating of tokamak plasmas

    International Nuclear Information System (INIS)

    Brambilla, M.

    1986-05-01

    We present a complete set of equations for the numerical simulation of ion cyclotron heating of tokamak plasmas. The model includes the full geometry of the tokamak equilibrium, full parallel dispersion, and perpendicular dispersion to second order in the Larmor radius. It is therefore capable of describing correctly ion cyclotron damping at the fundamental and first harmonic, as well as mode conversion to the ion Bernstein wave and/or the shear Alfven wave, depending on the heating scenario. It includes also electron magnitude pumping and Landau damping, the latter to lowest order in msub(e)/msub(i). Relying on the knowledge gained from slab and ray tracing analysis, we also situate with respect to this standard model some of the further approximations which are commonly encountered in the literature. Finally, two procedures for the numerical solution of the standard model are proposed. (orig.)

  11. Dispersion relation approach to sub-barrier heavy ion fusion reactions

    International Nuclear Information System (INIS)

    Franzin, V.L.M.; Hussein, M.S.

    1986-07-01

    With the aid of an inverse dispersion relation, which gives the imaginary part of the fusion inclusive polarization potential (IPP) in terms of the principal part integral involving the real part of the IPP, the sub-barrier fusion of heavy ions is discussed. The system 16 O+ A Sm is taken as an example. The reactive content of the extracted IPP is analysed within the coupled channels theory. (Author) [pt

  12. Modulation instability and dissipative rogue waves in ion-beam plasma: Roles of ionization, recombination, and electron attachment

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Shimin, E-mail: gsm861@126.com; Mei, Liquan, E-mail: lqmei@mail.xjtu.edu.cn [School of Mathematics and Statistics, Xi' an Jiaotong University, Xi' an 710049 (China)

    2014-11-15

    The amplitude modulation of ion-acoustic waves is investigated in an unmagnetized plasma containing positive ions, negative ions, and electrons obeying a kappa-type distribution that is penetrated by a positive ion beam. By considering dissipative mechanisms, including ionization, negative-positive ion recombination, and electron attachment, we introduce a comprehensive model for the plasma with the effects of sources and sinks. Via reductive perturbation theory, the modified nonlinear Schrödinger equation with a dissipative term is derived to govern the dynamics of the modulated waves. The effect of the plasma parameters on the modulation instability criterion for the modified nonlinear Schrödinger equation is numerically investigated in detail. Within the unstable region, first- and second-order dissipative ion-acoustic rogue waves are present. The effect of the plasma parameters on the characteristics of the dissipative rogue waves is also discussed.

  13. Pitch Angle Dependence of Drift Resonant Ions Observed by the Van Allen Probes

    Science.gov (United States)

    Rankin, R.; Wang, C.; Wang, Y.; Zong, Q. G.; Zhou, X.

    2017-12-01

    Acceleration and modulation of ring current ions by poloidal mode ULF waves is investigated. A simplified MHD model of ULF waves in a dipole magnetic field is presented that includes phase mixing to perpendicular scales determined by the ionospheric Pedersen conductivity. The wave model is combined with a full Lorentz force test particle code to study drift and drift bounce resonance wave-particle interactions. Ion trajectories are traced backward-in-time to an assumed form of the distribution function, and Liouville's method is used to reconstruct the phase space density response (PSD) poloidal mode waves observed by the Van Allen Probes. In spite of its apparent simplicity, simulations using the wave and test particle models are able to explain the acceleration of ions and energy dispersion observed by the Van Allen Probes. The paper focuses on the pitch angle evolution of the initial PSD as it responds to the action of ULF waves. An interesting aspect of the study is the formation of butterfly ion distributions as ions make periodic radial oscillations across L. Ions become trapped in an effective potential well across a limited range of L and follow trajectories that cause them to surf along constant phase fronts. The impications of this new trapping mechanism for both ions and electrons is discussed.

  14. Robustness, Death of Spiral Wave in the Network of Neurons under Partial Ion Channel Block

    International Nuclear Information System (INIS)

    Jun, Ma; Long, Huang; Chun-Ni, Wang; Zhong-Sheng, Pu

    2013-01-01

    The development of spiral wave in a two-dimensional square array due to partial ion channel block (Potassium, Sodium) is investigated, the dynamics of the node is described by Hodgkin—Huxley neuron and these neurons are coupled with nearest neighbor connection. The parameter ratio x Na (and x K ), which defines the ratio of working ion channel number of sodium (potassium) to the total ion channel number of sodium (and potassium), is used to measure the shift conductance induced by channel block. The distribution of statistical variable R in the two-parameter phase space (parameter ratio vs. poisoning area) is extensively calculated to mark the parameter region for transition of spiral wave induced by partial ion channel block, the area with smaller factors of synchronization R is associated the parameter region that spiral wave keeps alive and robust to the channel poisoning. Spiral wave keeps alive when the poisoned area (potassium or sodium) and degree of intoxication are small, distinct transition (death, several spiral waves coexist or multi-arm spiral wave emergence) occurs under moderate ratio x Na (and x K ) when the size of blocked area exceeds certain thresholds. Breakup of spiral wave occurs and multi-arm of spiral waves are observed when the channel noise is considered. (interdisciplinary physics and related areas of science and technology)

  15. Anomalous width variation of rarefactive ion acoustic solitary waves in the context of auroral plasmas

    Directory of Open Access Journals (Sweden)

    S. S. Ghosh

    2004-01-01

    Full Text Available The presence of dynamic, large amplitude solitary waves in the auroral regions of space is well known. Since their velocities are of the order of the ion acoustic speed, they may well be considered as being generated from the nonlinear evolution of ion acoustic waves. However, they do not show the expected width-amplitude correlation for K-dV solitons. Recent POLAR observations have actually revealed that the low altitude rarefactive ion acoustic solitary waves are associated with an increase in the width with increasing amplitude. This indicates that a weakly nonlinear theory is not appropriate to describe the solitary structures in the auroral regions. In the present work, a fully nonlinear analysis based on Sagdeev pseudopotential technique has been adopted for both parallel and oblique propagation of rarefactive solitary waves in a two electron temperature multi-ion plasma. The large amplitude solutions have consistently shown an increase in the width with increasing amplitude. The width-amplitude variation profile of obliquely propagating rarefactive solitary waves in a magnetized plasma have been compared with the recent POLAR observations. The width-amplitude variation pattern is found to fit well with the analytical results. It indicates that a fully nonlinear theory of ion acoustic solitary waves may well explain the observed anomalous width variations of large amplitude structures in the auroral region.

  16. A theoretical investigation of the collective acceleration of cluster ions with accelerated potential waves

    International Nuclear Information System (INIS)

    Suzuki, Hiroshi; Enjoji, Hiroshi; Kawaguchi, Motoichi; Noritake, Toshiya

    1984-01-01

    A theoretical treatment of the acceleration of cluster ions for additional heating of fusion plasma using the trapping effect in an accelerated potential wave is described. The conceptual design of the accelerator is the same as that by Enjoji, and the potential wave used is sinusoidal. For simplicity, collisions among cluster ions and the resulting breakups are neglected. The masses of the cluster ions are specified to range from 100 m sub(D) to 1000 m sub(D) (m sub(D): mass of a deuterium atom). Theoretical treatment is carried out only for the injection velocity which coincides with the phase velocity of the applied wave at the entrance of the accelerator. An equation describing the rate for successful acceleration of ions with a certain mass is deduced for the continuous injection of cluster ions. Computation for a typical mass distribution shows that more than 70% of the injected particles are effectively accelerated. (author)

  17. Generalized dispersion relation for electron Bernstein waves in a non-Maxwellian magnetized anisotropic plasma

    International Nuclear Information System (INIS)

    Deeba, F.; Ahmad, Zahoor; Murtaza, G.

    2010-01-01

    A generalized dielectric constant for the electron Bernstein waves using non-Maxwellian distribution functions is derived in a collisionless, uniform magnetized plasma. Using the Neumann series expansion for the products of Bessel functions, we can derive the dispersion relations for both kappa and the generalized (r,q) distributions in a straightforward manner. The dispersion relations now become dependent upon the spectral indices κ and (r,q) for the kappa and the generalized (r,q) distribution, respectively. Our results show how the non-Maxwellian dispersion curves deviate from the Maxwellian depending upon the values of the spectral indices chosen. It may be noted that the (r,q) dispersion relation is reduced to the kappa distribution for r=0 and q=κ+1, which, in turn, is further reducible to the Maxwellian distribution for κ→∞.

  18. INTERACTION OF NEUTRAL BEAM INJECTED FAST IONS WITH ION CYCLOTRON RESONANCE FREQUENCY WAVES

    International Nuclear Information System (INIS)

    CHOI, M.; CHAN, V.S.; CHIU, S.C.; OMELCHENKO, Y.A.; SENTOKU, Y.; STJOH, H.E.

    2003-01-01

    OAK B202 INTERACTION OF NEUTRAL BEAM INJECTED FAST IONS WITH CYCLOTRON RESONANCE FREQUENCY WAVES. Existing tokamaks such as DIII-D and future experiments like ITER employ both NB injection (NBI) and ion-cyclotron resonance heating (ICRH) for auxiliary heating and current drive. The presence of energetic particles produced by NBI can result in absorption of the Ion cyclotron radio frequency (ICRF) power. ICRF can also interact with the energetic beam ions to alter the characteristics of NBI momentum deposition and resultant impact on current drive and plasma rotation. To study the synergism between NBI and ICRF, a simple physical model for the slowing-down of NB injected fast ions is implemented in a Monte-Carlo rf orbit code. This paper presents the first results. The velocity space distributions of energetic ions generated by ICRF and NBI are calculated and compared. The change in mechanical momentum of the beam and an estimate of its impact on the NB-driven current are presented and compared with ONETWO simulation results

  19. Simultaneous ion detection in a mass spectrometer with variable mass dispersion

    International Nuclear Information System (INIS)

    Tuithof, H.H.

    1977-01-01

    This thesis mainly describes the ion-optics of a magnetic mass spectrometer system, especially applied to the projection of a significant part of the mass spectrum onto a flat ion-detector. The complete detector consists of a channeltron electron multiplier array with phosphor screen and a Vidicon-multichannel analyzer combination for simultaneous read-out. In order to optimise the spectral range projected onto the channelplate, by varying the mass dispersion and to rotate the oblique angle of the mass focal plane with respect to the detector surface, the sector magnet has been combined with electrostatic and magnetic quadrupole lenses. This detector will find wide application in the analysis of minute sample quantities, in the recording of extremely short ion events (large molecules) and at collision activation mass-spectrometry studies

  20. Effect of magnetic field on the wave dispersion relation in three-dimensional dusty plasma crystals

    International Nuclear Information System (INIS)

    Yang Xuefeng; Wang Zhengxiong

    2012-01-01

    Three-dimensional plasma crystals under microgravity condition are investigated by taking into account an external magnetic field. The wave dispersion relations of dust lattice modes in the body centered cubic (bcc) and the face centered cubic (fcc) plasma crystals are obtained explicitly when the magnetic field is perpendicular to the wave motion. The wave dispersion relations of dust lattice modes in the bcc and fcc plasma crystals are calculated numerically when the magnetic field is in an arbitrary direction. The numerical results show that one longitudinal mode and two transverse modes are coupled due to the Lorentz force in the magnetic field. Moreover, three wave modes, i.e., the high frequency phonon mode, the low frequency phonon mode, and the optical mode, are obtained. The optical mode and at least one phonon mode are hybrid modes. When the magnetic field is neither parallel nor perpendicular to the primitive wave motion, all the three wave modes are hybrid modes and do not have any intersection points. It is also found that with increasing the magnetic field strength, the frequency of the optical mode increases and has a cutoff at the cyclotron frequency of the dust particles in the limit of long wavelength, and the mode mixings for both the optical mode and the high frequency phonon mode increase. The acoustic velocity of the low frequency phonon mode is zero. In addition, the acoustic velocity of the high frequency phonon mode depends on the angle of the magnetic field and the wave motion but does not depend on the magnetic field strength.

  1. Dispersive solitary wave solutions of Kadomtsev-Petviashvili and modified Kadomtsev-Petviashvili dynamical equations in unmagnetized dust plasma

    Science.gov (United States)

    Seadawy, A. R.; El-Rashidy, K.

    2018-03-01

    The Kadomtsev-Petviashvili (KP) and modified KP equations are two of the most universal models in nonlinear wave theory, which arises as a reduction of system with quadratic nonlinearity which admit weakly dispersive waves. The generalized extended tanh method and the F-expansion method are used to derive exact solitary waves solutions of KP and modified KP equations. The region of solutions are displayed graphically.

  2. Nonlinear ion-acoustic structures in a nonextensive electron–positron–ion–dust plasma: Modulational instability and rogue waves

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Shimin, E-mail: gsm861@126.com [School of Mathematics and Statistics, Xi’an Jiaotong University, Xi’an, 710049 (China); Research Group MAC, Centrum Wiskunde and Informatica, Amsterdam, 1098XG (Netherlands); Mei, Liquan, E-mail: lqmei@mail.xjtu.edu.cn [School of Mathematics and Statistics, Xi’an Jiaotong University, Xi’an, 710049 (China); Center for Computational Geosciences, Xi’an Jiaotong University, Xi’an, 710049 (China); Sun, Anbang [Research Group MAC, Centrum Wiskunde and Informatica, Amsterdam, 1098XG (Netherlands)

    2013-05-15

    The nonlinear propagation of planar and nonplanar (cylindrical and spherical) ion-acoustic waves in an unmagnetized electron–positron–ion–dust plasma with two-electron temperature distributions is investigated in the context of the nonextensive statistics. Using the reductive perturbation method, a modified nonlinear Schrödinger equation is derived for the potential wave amplitude. The effects of plasma parameters on the modulational instability of ion-acoustic waves are discussed in detail for planar as well as for cylindrical and spherical geometries. In addition, for the planar case, we analyze how the plasma parameters influence the nonlinear structures of the first- and second-order ion-acoustic rogue waves within the modulational instability region. The present results may be helpful in providing a good fit between the theoretical analysis and real applications in future spatial observations and laboratory plasma experiments. -- Highlights: ► Modulational instability of ion-acoustic waves in a new plasma model is discussed. ► Tsallis’s statistics is considered in the model. ► The second-order ion-acoustic rogue wave is studied for the first time.

  3. Nonlinear ion-acoustic structures in a nonextensive electron–positron–ion–dust plasma: Modulational instability and rogue waves

    International Nuclear Information System (INIS)

    Guo, Shimin; Mei, Liquan; Sun, Anbang

    2013-01-01

    The nonlinear propagation of planar and nonplanar (cylindrical and spherical) ion-acoustic waves in an unmagnetized electron–positron–ion–dust plasma with two-electron temperature distributions is investigated in the context of the nonextensive statistics. Using the reductive perturbation method, a modified nonlinear Schrödinger equation is derived for the potential wave amplitude. The effects of plasma parameters on the modulational instability of ion-acoustic waves are discussed in detail for planar as well as for cylindrical and spherical geometries. In addition, for the planar case, we analyze how the plasma parameters influence the nonlinear structures of the first- and second-order ion-acoustic rogue waves within the modulational instability region. The present results may be helpful in providing a good fit between the theoretical analysis and real applications in future spatial observations and laboratory plasma experiments. -- Highlights: ► Modulational instability of ion-acoustic waves in a new plasma model is discussed. ► Tsallis’s statistics is considered in the model. ► The second-order ion-acoustic rogue wave is studied for the first time

  4. Spin-waves in Antiferromagnetic Single-crystal LiFePO4

    International Nuclear Information System (INIS)

    Li, Jiying; Garlea, Vasile O.; Zarestky, Jarel; Vaknin, D.

    2006-01-01

    Spin-wave dispersions in the antiferromagnetic state of single-crystal LiFePO 4 were determined by inelastic neutron scattering measurements. The dispersion curves measured from the (0,1,0) reflection along both a* and b* reciprocal-space directions reflect the anisotropic coupling of the layered Fe 2+ (S=2) spin system. The spin-wave dispersion curves were theoretically modeled using linear spin-wave theory by including in the spin Hamiltonian in-plane nearest- and next-nearest-neighbor interactions (J 1 and J 2 ), inter-plane nearest-neighbor interactions (J(perpendicular)) and a single-ion anisotropy (D). A weak (0,1,0) magnetic peak was observed in elastic neutron scattering studies of the same crystal indicating that the ground state of the staggered iron moments is not along the (0,1,0) direction, as previously reported from polycrystalline samples studies, but slightly rotated away from this axis.

  5. Slow cyclotron waves in a waveguide with a relativistic electron beam

    International Nuclear Information System (INIS)

    Korenev, I.L.; Yudin, L.A.; Mustafin, Kh.Kh.

    1979-01-01

    Using the analytical methods the problem about propagation of waves of a small amplitude in an electron beam (without ions), moving along the axis of a smooth waveguide in the longitudinal magnetic field is considered. The main attention is paid to dispersion.characteristics and the slow cyclotron waves intended for ion acceleration. The problems connected with utilization of these waves for ion acceleration are discussed. The estimation shows that when a system of excitation of an accelerating wave has a wide range, i.e. excited is a great set of slow cyclotron modes, the accelerating field structure significantly changes at a distance of several dozens beam radii, and synchronism supply between the wave and accelerating ions becomes an impracticable task. So it is necessary to have a narrow-band excitation system to excite only a single mode. It is noted that the model used of a uniform beam density along the cross section is an idealization permitting to simplify analytical consideration. The presence of the radial density change in an undisturbed beam will lead to some other cyclotron wave field structure. However, such a change will not give any qualitative differences in comparison with the results obtained

  6. Investigation of Ion Absorption of the High Harmonic Fast Wave in NSTX using HPRT

    International Nuclear Information System (INIS)

    Rosenberg, A.; Menard, J.E.; LeBlanc, B.P.

    2001-01-01

    Understanding high harmonic fast wave (HHFW) power absorption by ions in a spherical torus (ST) is of critical importance to assessing the wave's viability as a means of heating and especially driving current. In this work, the HPRT code is used to calculate absorption for helium and deuterium, with and without minority hydrogen in National Spherical Torus Experiment (NSTX) plasmas using experimental EFIT code equilibria and kinetic profiles. HPRT is a two-dimensional ray-tracing code which uses the full hot plasma dielectric to compute the perpendicular wave number along the hot electron and cold ion plasma ray path. Ion and electron absorption dependence on antenna phasing, ion temperature, beta (subscript t), and minority temperature and concentration is analyzed. These results form the basis for comparisons with other codes, such as CURRAY, METS, TORIC, and AORSA

  7. Heating and acceleration of solar wind ions by turbulent wave spectrum in inhomogeneous expanding plasma

    Energy Technology Data Exchange (ETDEWEB)

    Ofman, Leon, E-mail: Leon.Ofman@nasa.gov [Department of Physics, The Catholic University of America, Washington, DC (United States); NASA Goddard Space Flight Center, Greenbelt, MD (United States); Visiting, Department of Geosciences, Tel Aviv University, Tel Aviv (Israel); Ozak, Nataly [Centre for mathematical Plasma Astrophysics, KU Leuven, Celestijnenlaan 200B, 3001 Leuven (Belgium); Viñas, Adolfo F. [NASA Goddard Space Flight Center, Greenbelt, MD (United States)

    2016-03-25

    Near the Sun (< 10R{sub s}) the acceleration, heating, and propagation of the solar wind are likely affected by the background inhomogeneities of the magnetized plasma. The heating and the acceleration of the solar wind ions by turbulent wave spectrum in inhomogeneous plasma is studied using a 2.5D hybrid model. The hybrid model describes the kinetics of the ions, while the electrons are modeled as massless neutralizing fluid in an expanding box approach. Turbulent magnetic fluctuations dominated by power-law frequency spectra, which are evident from in-situ as well as remote sensing measurements, are used in our models. The effects of background density inhomogeneity across the magnetic field on the resonant ion heating are studied. The effect of super-Alfvénic ion drift on the ion heating is investigated. It is found that the turbulent wave spectrum of initially parallel propagating waves cascades to oblique modes, and leads to enhanced resonant ion heating due to the inhomogeneity. The acceleration of the solar wind ions is achieved by the parametric instability of large amplitude waves in the spectrum, and is also affected by the inhomogeneity. The results of the study provide the ion temperature anisotropy and drift velocity temporal evolution due to relaxation of the instability. The non-Maxwellian velocity distribution functions (VDFs) of the ions are modeled in the inhomogeneous solar wind plasma in the acceleration region close to the Sun.

  8. Shear wave velocity model beneath CBJI station West Java, Indonesia from joint inversion of teleseismic receiver functions and surface wave dispersion

    Science.gov (United States)

    Simanungkalit, R. H.; Anggono, T.; Syuhada; Amran, A.; Supriyanto

    2018-03-01

    Earthquake signal observations around the world allow seismologists to obtain the information of internal structure of the Earth especially the Earth’s crust. In this study, we used joint inversion of receiver functions and surface wave group velocities to investigate crustal structure beneath CBJI station in West Java, Indonesia. Receiver function were calculated from earthquakes with magnitude more than 5 and at distance 30°-90°. Surface wave group velocities were calculated using frequency time analysis from earthquakes at distance of 30°- 40°. We inverted shear wave velocity model beneath the station by conducting joint inversion from receiver functions and surface wave dispersions. We suggest that the crustal thickness beneath CBJI station, West Java, Indonesia is about 35 km.

  9. Kinetic Alfven wave in the presence of kappa distribution function in plasma sheet boundary layer

    Energy Technology Data Exchange (ETDEWEB)

    Shrivastava, G., E-mail: geetphy9@gmail.com; Ahirwar, G. [School of Studies in Physics, Vikram University, Ujjain India (India); Shrivastava, J., E-mail: jayashrivastava2007@gmail.com [Dronacharya Group of Institutions, Greater Noida-India (India)

    2015-07-31

    The particle aspect approach is adopted to investigate the trajectories of charged particles in the electromagnetic field of kinetic Alfven wave. Expressions are found for the dispersion relation, damping/growth rate and associated currents in the presence of kappa distribution function. Kinetic effect of electrons and ions are included to study kinetic Alfven wave because both are important in the transition region. It is found that the ratio β of electron thermal energy density to magnetic field energy density and the ratio of ion to electron thermal temperature (T{sub i}/T{sub e}), and kappa distribution function affect the dispersion relation, damping/growth rate and associated currents in both cases(warm and cold electron limit).The treatment of kinetic Alfven wave instability is based on assumption that the plasma consist of resonant and non resonant particles. The resonant particles participate in an energy exchange process, whereas the non resonant particles support the oscillatory motion of the wave.

  10. Electromagnetic ion cyclotron waves observed near the oxygen cyclotron frequency by ISEE 1 and 2

    International Nuclear Information System (INIS)

    Fraser, B.J.; Samson, J.C.; Hu, Y.D.; McPherron, R.L.; Russell, C.T.

    1992-01-01

    Pc 2 electromagnetic ion cyclotron waves at 0.1 waves at 0.1 Hz, near the oxygen cyclotron frequency, have been observed by ISEE 1 and 2 between L = 7.6 and 5.8 on an inbound near-equatorial pass in the dusk sector. The waves occurred in a thick plasmapause of width ∼ 1.5 R E and penetrated ∼1 R E into the plasmasphere. Wave onset was accompanied by significant increases in the thermal (0-100 eV) He + and the warm (0.1-16 keV/e) O + and He + heavy ion populations. The most intense waves (8 nT) were observed in the outer plasmasphere where convection drift velocities (E x B)/B 2 were largest and the Alfven velocity was a minimum. Wave polarization is predominantly left-handed with propagation almost parallel to the ambient magnetic field, and the spectral slot and polarization reversal predicted by cold plasma propagation theory are identified in the wave data. Poynting fluxes calculated during the first 15 min of the event show wave energy propagation directions both parallel and antiparallel to the field. Computations of the experimental wave spectra during the passage through the plasmapause show that the spectral slots relate to local plasma parameters, possibly suggesting an ion cyclotron wave growth source near the spacecraft. A regular wave packet structure seen over the first 30 min of the event may be attributed to the modulation of this energy source by the Pc 5 waves seen at the same time. Overall, the results are considered an example of an electromagnetic ion cyclotron wave-particle interaction occurring during the outer plasmasphere refilling process at the time of the substorm recovery phase

  11. Approximate Dispersion Relations for Waves on Arbitrary Shear Flows

    Science.gov (United States)

    Ellingsen, S. À.; Li, Y.

    2017-12-01

    An approximate dispersion relation is derived and presented for linear surface waves atop a shear current whose magnitude and direction can vary arbitrarily with depth. The approximation, derived to first order of deviation from potential flow, is shown to produce good approximations at all wavelengths for a wide range of naturally occuring shear flows as well as widely used model flows. The relation reduces in many cases to a 3-D generalization of the much used approximation by Skop (1987), developed further by Kirby and Chen (1989), but is shown to be more robust, succeeding in situations where the Kirby and Chen model fails. The two approximations incur the same numerical cost and difficulty. While the Kirby and Chen approximation is excellent for a wide range of currents, the exact criteria for its applicability have not been known. We explain the apparently serendipitous success of the latter and derive proper conditions of applicability for both approximate dispersion relations. Our new model has a greater range of applicability. A second order approximation is also derived. It greatly improves accuracy, which is shown to be important in difficult cases. It has an advantage over the corresponding second-order expression proposed by Kirby and Chen that its criterion of accuracy is explicitly known, which is not currently the case for the latter to our knowledge. Our second-order term is also arguably significantly simpler to implement, and more physically transparent, than its sibling due to Kirby and Chen.Plain Language SummaryIn order to answer key questions such as how the ocean surface affects the climate, erodes the coastline and transports nutrients, we must understand how waves move. This is not so easy when depth varying currents are present, as they often are in coastal waters. We have developed a modeling tool for accurately predicting wave properties in such situations, ready for use, for example, in the complex oceanographic computer models. Our

  12. A discontinuous Galerkin approach for conservative modeling of fully nonlinear and weakly dispersive wave transformations

    Science.gov (United States)

    Sharifian, Mohammad Kazem; Kesserwani, Georges; Hassanzadeh, Yousef

    2018-05-01

    This work extends a robust second-order Runge-Kutta Discontinuous Galerkin (RKDG2) method to solve the fully nonlinear and weakly dispersive flows, within a scope to simultaneously address accuracy, conservativeness, cost-efficiency and practical needs. The mathematical model governing such flows is based on a variant form of the Green-Naghdi (GN) equations decomposed as a hyperbolic shallow water system with an elliptic source term. Practical features of relevance (i.e. conservative modeling over irregular terrain with wetting and drying and local slope limiting) have been restored from an RKDG2 solver to the Nonlinear Shallow Water (NSW) equations, alongside new considerations to integrate elliptic source terms (i.e. via a fourth-order local discretization of the topography) and to enable local capturing of breaking waves (i.e. via adding a detector for switching off the dispersive terms). Numerical results are presented, demonstrating the overall capability of the proposed approach in achieving realistic prediction of nearshore wave processes involving both nonlinearity and dispersion effects within a single model.

  13. Nonlinear Waveforms for Ion-Acoustic Waves in Weakly Relativistic Plasma of Warm Ion-Fluid and Isothermal Electrons

    Directory of Open Access Journals (Sweden)

    S. A. El-Wakil

    2012-01-01

    Full Text Available The reductive perturbation method has been employed to derive the Korteweg-de Vries (KdV equation for small- but finite-amplitude electrostatic ion-acoustic waves in weakly relativistic plasma consisting of warm ions and isothermal electrons. An algebraic method with computerized symbolic computation is applied in obtaining a series of exact solutions of the KdV equation. Numerical studies have been made using plasma parameters which reveal different solutions, that is, bell-shaped solitary pulses, rational pulses, and solutions with singularity at finite points, which called “blowup” solutions in addition to the propagation of an explosive pulses. The weakly relativistic effect is found to significantly change the basic properties (namely, the amplitude and the width of the ion-acoustic waves. The result of the present investigation may be applicable to some plasma environments, such as ionosphere region.

  14. Parametrically induced low-frequency waves in weakly inhomogeneous magnetized plasmas

    International Nuclear Information System (INIS)

    Pesic, S.

    1981-01-01

    The linear dispersion relation governing the parametric interaction of a lower hybrid pump wave with a weakly-inhomogeneous current carrying hot plasma confined by a helical magnetic field is derived and solved numerically. The stability boundaries are delineated over a wide range in the k-space. The frequency and growth rate of decay instabilities are calculated for plasma parameters relevant to lower hybrid plasma heating experiments. The parametric excitation of drift waves and ion cyclotron current instabilities is discussed. In the low-density plasma region low minimum thresholds and high growth rates are obtained for the pump decay into ion cyclotron and nonresonant quasimodes. The spatial amplification of hot ion Bernstein waves and nonresonant quasimodes dominate in the plasma core (ω 0 /ωsub(LH) < 2). The presented theoretical results are in qualitative agreement with current LH plasma heating experiments. (author)

  15. Electrostatic quasi-monochromatic waves in the downstream region of the Earth's bow shock based on Geotail observations

    Science.gov (United States)

    Shin, K.; Kojima, H.; Matsumoto, H.; Mukai, T.

    2007-02-01

    Geotail plasma wave observations show the existence of intense electrostatic quasi-monochromatic (EQM) waves in the downstream region of the Earth's bow shock. They oscillate parallel to the ambient magnetic field and appear at frequencies between the electron plasma and ion plasma frequencies. Although these waves have been believed to be Doppler-shifted ion acoustic waves, the typical plasma parameters observed in the downstream region do not support the generation conditions for ion acoustic waves. In this paper, the existence of cold electron beam-like components accompanying EQM waves is considered based on waveform and statistical analyses. Linear dispersion analyses using realistic plasma parameters revealed that the cold electron beams cause destabilization of electron acoustic waves at frequencies consistent with those of observed EQM waves. The results of observations and linear analyses suggest that EQM waves are generated by the destabilization of the electron acoustic mode.

  16. The Ion Cyclotron, Lower Hybrid, and Alfven Wave Heating Methods

    International Nuclear Information System (INIS)

    Koch, R.

    2004-01-01

    This lecture covers the practical features and experimental results of the three heating methods. The emphasis is on ion cyclotron heating. First, we briefly come back to the main non-collisional heating mechanisms and to the particular features of the quasilinear coefficient in the ion cyclotron range of frequencies (ICRF). The specific case of the ion-ion hybrid resonance is treated, as well as the polarisation issue and minority heating scheme. The various ICRF scenarios are reviewed. The experimental applications of ion cyclotron resonance heating (ICRH) systems are outlined. Then, the lower hybrid and Alfven wave heating and current drive experimental results are covered more briefly. Where applicable, the prospects for ITER are commented

  17. Smooth and non-smooth traveling wave solutions of a class of nonlinear dispersive equation

    International Nuclear Information System (INIS)

    Zhao Xiaoshan; Wu Aidi; He Wenzhang

    2009-01-01

    There is the widespread existence of wave phenomena in physics, mechanics. This clearly necessitates a study of traveling waves in depth and of the modeling and analysis involved. In this paper, we study a nonlinear dispersive K(n,-n,2n) equation, which can be regarded as a generalized K(n,n) equation. Applying the bifurcation theory and the method of phase portraits analysis, we obtain the dynamical behavior and special exact solutions of the K(n,-n,2n) equation. As a result, the conditions under which peakon and compacton solutions appear are also given and the analytic expressions of peakon solutions, compacton and periodic cusp wave solutions are obtained.

  18. Effect of negative ions on current growth and ionizing wave propagation in air

    International Nuclear Information System (INIS)

    Kline, L.E.

    1975-01-01

    The spatiotemporal development of electron and ion densities, electric fields, and luminosity are calculated for electron pulse experiments in overvolted parallel-plane gaps by numerically solving continuity equations together with Poisson's equation. Experimental coefficients for primary ionization, cathode photoemission, photoionization, and luminosity are used. Unambiguous determination of the coefficients for attachment, detachment, and charge transfer is not possible from available experimental results. Therefore, the calculations are repeated for three sets of coefficients for these processes, corresponding to the following assumptions: unstable negative ions, stable negative ions, and no negative ions. The results of the calculations show, in each case, that the electron pulse initiates an avalanche which grows exponentially until the onset of space-charge effects. The calculated growth rate is strongly affected by the assumed attachment, detachment, and charge-transfer coefficients. When the total number of electrons in the avalanche reaches approx.10 8 , anode- and cathode-directed ionizing waves, or streamers, develop from the avalanche and produce a weakly ionized filamentary plasma. The calculated ionizing wave velocities are strongly increasing functions of the space-charge--enhanced electric field within the waves and are insensitive to the assumed attachment, detachment, and charge-transfer coefficients. The numerically calculated ionizing wave velocities are in approximate agreement with a simple analytical theory

  19. Noninvasive evaluation of reverse atrial remodeling after catheter ablation of atrial fibrillation by P wave dispersion.

    Science.gov (United States)

    Fujimoto, Yuhi; Yodogawa, Kenji; Takahashi, Kenta; Tsuboi, Ippei; Hayashi, Hiroshi; Uetake, Shunsuke; Iwasaki, Yu-Ki; Hayashi, Meiso; Miyauchi, Yasushi; Shimizu, Wataru

    2017-11-01

    Atrial fibrillation (AF) itself creates structural and electrophysiological changes such as atrial enlargement, shortening of refractory period and decrease in conduction velocity, called "atrial remodeling", promoting its persistence. Although the remodeling process is considered to be reversible, it has not been elucidated in detail. The aim of this study was to assess the feasibility of P wave dispersion in the assessment of reverse atrial remodeling following catheter ablation of AF. Consecutive 126 patients (88 males, age 63.0 ± 10.4 years) who underwent catheter ablation for paroxysmal AF were investigated. P wave dispersion was calculated from the 12 lead ECG before, 1 day, 1 month, 3 months and 6 months after the procedure. Left atrial diameter (LAD), left atrial volume index (LAVI), left ventricular ejection fraction (LVEF), transmitral flow velocity waveform (E/A), and tissue Doppler (E/e') on echocardiography, plasma B-type natriuretic peptide (BNP) concentrations, serum creatinine, and estimated glomerular filtration rate (eGFR) were also measured. Of all patients, 103 subjects remained free of AF for 1 year follow-up. In these patients, P wave dispersion was not changed 1 day and 1 month after the procedure. However, it was significantly decreased at 3 and 6 months (50.1 ± 14.8 to 45.4 ± 14.4 ms, p < 0.05, 45.2 ± 9.9 ms, p < 0.05, respectively). Plasma BNP concentrations, LAD and LAVI were decreased (81.1 ± 103.8 to 44.8 ± 38.3 pg/mL, p < 0.05, 38.2 ± 5.7 to 35.9 ± 5.6 mm, p < 0.05, 33.3 ± 14.2 to 29.3 ± 12.3 mL/m 2 , p < 0.05) at 6 months after the procedure. There were no significant changes in LVEF, E/A, E/e', serum creatinine, and eGFR during the follow up period. P wave dispersion was decreased at 3 and 6 months after catheter ablation in patients without recurrence of AF. P wave dispersion is useful for assessment of reverse remodeling after catheter ablation of AF.

  20. Characteristics of resin floc dispersion of anion and cation exchange resin in precoat filter using powdered ion exchange resin

    Energy Technology Data Exchange (ETDEWEB)

    Adachi, Tetsurou (Nitto Denko Corp., Ibaraki, Osaka (Japan)); Sawa, Toshio; Shindoh, Toshikazu

    1989-09-01

    The filtration performance of mixed filter aid consisting of powdered anion and cation exchange resins used in the precoat filter is closely related to the characteristics of resin floc dispersion. The factors related to resin floc dispersion of anion and cation exchange resin were investigated by measuring the specific settle volume of resin floc as an evaluating index in addition to the measurement of physical, chemical and electrochemical properties of powdered ion exchange resin. The effect of adsorption of iron oxide and polymer electrolyte and of ion exchange were determined. In addition, considered floc dispersion with adsorbing iron oxide, it was assumed that the amount and filling ratio of resin floc were related to summation and multiplication of surface electric charge respectively. An experimental expression was obtained for simulation of the change of specific settle volume of resin floc by particle size, surface area, ion exchange capacity and degree of ionization of the powdered ion exchange resin. (author).

  1. Characteristics of resin floc dispersion of anion and cation exchange resin in precoat filter using powdered ion exchange resin

    International Nuclear Information System (INIS)

    Adachi, Tetsurou; Sawa, Toshio; Shindoh, Toshikazu.

    1989-01-01

    The filtration performance of mixed filter aid consisting of powdered anion and cation exchange resins used in the precoat filter is closely related to the characteristics of resin floc dispersion. The factors related to resin floc dispersion of anion and cation exchange resin were investigated by measuring the specific settle volume of resin floc as an evaluating index in addition to the measurement of physical, chemical and electrochemical properties of powdered ion exchange resin. The effect of adsorption of iron oxide and polymer electrolyte and of ion exchange were determined. In addition, considered floc dispersion with adsorbing iron oxide, it was assumed that the amount and filling ratio of resin floc were related to summation and multiplication of surface electric charge respectively. An experimental expression was obtained for simulation of the change of specific settle volume of resin floc by particle size, surface area, ion exchange capacity and degree of ionization of the powdered ion exchange resin. (author)

  2. Confinement of surface waves at the air-water interface to control aerosol size and dispersity

    Science.gov (United States)

    Nazarzadeh, Elijah; Wilson, Rab; King, Xi; Reboud, Julien; Tassieri, Manlio; Cooper, Jonathan M.

    2017-11-01

    The precise control over the size and dispersity of droplets, produced within aerosols, is of great interest across many manufacturing, food, cosmetic, and medical industries. Amongst these applications, the delivery of new classes of high value drugs to the lungs has recently attracted significant attention from pharmaceutical companies. This is commonly achieved through the mechanical excitation of surface waves at the air liquid interface of a parent liquid volume. Previous studies have established a correlation between the wavelength on the surface of liquid and the final aerosol size. In this work, we show that the droplet size distribution of aerosols can be controlled by constraining the liquid inside micron-sized cavities and coupling surface acoustic waves into different volumes of liquid inside micro-grids. In particular, we show that by reducing the characteristic physical confinement size (i.e., either the initial liquid volume or the cavities' diameters), higher harmonics of capillary waves are revealed with a consequent reduction of both aerosol mean size and dispersity. In doing so, we provide a new method for the generation and fine control of aerosols' sizes distribution.

  3. Exact solitary ion acoustic waves in a magnetoplasma

    International Nuclear Information System (INIS)

    Ray, D.

    1979-01-01

    Solitary ion acoustic waves in a magnetoplasma have been studied by Shukla and Yu [J. Math. Phys. 19, 2506 (1978)]. A more rigorous study confirms the conditions that Shukla and Yu said would be necessary for humps. However, it is shown that a density cavity is also possible in the limiting case

  4. Determination of Zinc Ions in Environmental Samples by Dispersive Liquid- Liquid Micro Extraction and Atomic Absorption Spectroscopy

    Directory of Open Access Journals (Sweden)

    F. Arabi

    2012-11-01

    Full Text Available In this work preconcentration of the Zn ions was investigated in water sample by Dispersive liquid- liquid micro extraction (DLLME using chloroform as an extraction solvent, methanol as a disperser solvent and 8-Hydroxyquinoline as a chelating agent. The determination of extracted ions was done by graphite furnace atomic absorption spectrometry. The influence of various analytical parameters including pH, extraction and disperser solvent type and volume and concentration of the chelating agent on the extraction efficiency of analyses was investigated. After extraction, the enrichment factor was 26 and the detection limit of the method was 0.0033 µg l-1 and the relative standard deviations (R.S.D for five determinations of 1 ng/ml Zn were 7.41%. 

  5. Prediction of ion-exchange column breakthrough curves by constant-pattern wave approach.

    Science.gov (United States)

    Lee, I-Hsien; Kuan, Yu-Chung; Chern, Jia-Ming

    2008-03-21

    The release of heavy metals from industrial wastewaters represents one of major threats to environment. Compared with chemical precipitation method, fixed-bed ion-exchange process can effectively remove heavy metals from wastewaters and generate no hazardous sludge. In order to design and operate fixed-bed ion-exchange processes successfully, it is very important to understand the column dynamics. In this study, the column experiments for Cu2+/H+, Zn2+/H+, and Cd2+/H+ systems using Amberlite IR-120 were performed to measure the breakthrough curves under varying operating conditions. The experimental results showed that total cation concentration in the mobile-phase played a key role on the breakthrough curves; a higher feed concentration resulted in an earlier breakthrough. Furthermore, the column dynamics was also predicted by self-sharpening and constant-pattern wave models. The self-sharpening wave model assuming local ion-exchange equilibrium could provide a simple and quick estimation for the breakthrough volume, but the predicted breakthrough curves did not match the experimental data very well. On the contrary, the constant-pattern wave model using a constant driving force model for finite ion-exchange rate provided a better fit to the experimental data. The obtained liquid-phase mass transfer coefficient was correlated to the flow velocity and other operating parameters; the breakthrough curves under varying operating conditions could thus be predicted by the constant-pattern wave model using the correlation.

  6. Self similar asymptotics of the drift ion acoustic waves

    International Nuclear Information System (INIS)

    Taranov, V.B.

    2004-01-01

    A 3D model for the coupled drift and ion acoustic waves is considered. It is shown that self-similar solutions can exist due to the symmetry extension in asymptotic regimes. The form of these solutions is determined in the presence of the magnetic shear as well as in the shear less case. Some of the most symmetric exact solutions are obtained explicitly. In particular, solutions describing asymptotics of zonal flow interaction with monochromatic waves are presented and corresponding frequency shifts are determined

  7. Generation of lower hybrid and whistler waves by an ion velocity ring distribution

    International Nuclear Information System (INIS)

    Winske, D.; Daughton, W.

    2012-01-01

    Using fully kinetic simulations in two and three spatial dimensions, we consider the generation and nonlinear evolution of lower hybrid waves produced by a cold ion ring velocity distribution in a low beta plasma. We show that the initial development of the instability is very similar in two and three dimensions and not significantly modified by electromagnetic effects, consistent with linear theory. At saturation, the level of electric field fluctuations is a small fraction of the background thermal energy; the electric field and corresponding density fluctuations consist of long, field-aligned striations. Energy extracted from the ring goes primarily into heating the background ions and the electrons at comparable rates. The initial growth and saturation of the magnetic components of the lower hybrid waves are related to the electric field components, consistent with linear theory. As the growing electric field fluctuations saturate, parallel propagating whistler waves develop by the interaction of two lower hybrid waves. At later times, these whistlers are replaced by longer wavelength, parallel propagating whistlers that grow through the decay of the lower hybrid fluctuations. Wave matching conditions demonstrate these conversion processes of lower hybrid waves to whistler waves. The conversion efficiency (=ratio of the whistler wave energy to the energy in the saturated lower hybrid waves) is computed and found to be significant (∼15%) for the parameters of the three-dimensional simulation (and even larger in the two-dimensional simulation), although when normalized in terms of the initial kinetic energy in the ring ions the overall efficiency is very small ( −4 ). The results are compared with relevant linear and nonlinear theory.

  8. Stimulated scattering of electromagnetic waves carrying orbital angular momentum in quantum plasmas.

    Science.gov (United States)

    Shukla, P K; Eliasson, B; Stenflo, L

    2012-07-01

    We investigate stimulated scattering instabilities of coherent circularly polarized electromagnetic (CPEM) waves carrying orbital angular momentum (OAM) in dense quantum plasmas with degenerate electrons and nondegenerate ions. For this purpose, we employ the coupled equations for the CPEM wave vector potential and the driven (by the ponderomotive force of the CPEM waves) equations for the electron and ion plasma oscillations. The electrons are significantly affected by the quantum forces (viz., the quantum statistical pressure, the quantum Bohm potential, as well as the electron exchange and electron correlations due to electron spin), which are included in the framework of the quantum hydrodynamical description of the electrons. Furthermore, our investigation of the stimulated Brillouin instability of coherent CPEM waves uses the generalized ion momentum equation that includes strong ion coupling effects. The nonlinear equations for the coupled CPEM and quantum plasma waves are then analyzed to obtain nonlinear dispersion relations which exhibit stimulated Raman, stimulated Brillouin, and modulational instabilities of CPEM waves carrying OAM. The present results are useful for understanding the origin of scattered light off low-frequency density fluctuations in high-energy density plasmas where quantum effects are eminent.

  9. P wave duration and dispersion in patients with hyperthyroidism and the short-term effects of antithyroid treatment.

    Science.gov (United States)

    Guntekin, Unal; Gunes, Yilmaz; Simsek, Hakki; Tuncer, Mustafa; Arslan, Sevket

    2009-09-01

    Prolonged P wave duration and P wave dispersion (PWD) have been associated with an increased risk for atrial fibrillation (AF). Hyperthytodism is a frequent cause of atrial fibrillation (AF). Forty-two patients with newly diagnosed overt hyperthyroidism and 20 healthy people were enrolled in the study. Transthoracic echocardiography, 12 lead surface ECG and thyroid hormone levels were studied at the time of enrollment and after achievement of euthyroid state with propylthiouracil treatment. Maximum P wave duration (Pmax) (97.4+/-14.6 vs. 84.2+/-9.5 msec, phyperthyroid patients compared to control group. Pmax and PWD were significantly correlated with the presence of hyperthyroidism. Pmax (97.4+/-14.6 to 84.3+/-8.6 msec, phyperthyroidism. Diastolic dyfunction was seen in 5 patients at hyperthroid state but only in one patient at euthyroid state. Hyperthyroidism is associated with prolonged P wave duration and dispersion. Achievement of euthyroid state with propylthiouracil treatment results in shortening of P wave variables. Diastolic function may have a partial effect for the increased Pmax and PWD. Shortening of Pmax and PWD may be a marker for the prevention of AF with the anti-thyroid treatment.

  10. Comparison of magnetosonic wave and water group ion energy densities at Comet Giacobini-Zinner

    Science.gov (United States)

    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.

  11. Alfven waves in dusty plasmas with plasma particles described by anisotropic kappa distributions

    Energy Technology Data Exchange (ETDEWEB)

    Galvao, R. A.; Ziebell, L. F. [Instituto de Fisica, Universidade Federal do Rio Grande do Sul, Caixa Postal 15051, CEP: 91501-970, Porto Alegre, Rio Grande do Sul (Brazil); Gaelzer, R. [Instituto de Fisica e Matematica, Universidade Federal de Pelotas, Caixa Postal 354-Campus UFPel, CEP: 96010-900 Pelotas, Rio Grande do Sul (Brazil); Juli, M. C. de [Centro de Radio-Astronomia e Astrofisica Mackenzie-CRAAM, Universidade Presbiteriana Mackenzie, Rua da Consolacao 896, CEP: 01302-907 Sao Paulo, Sao Paulo (Brazil)

    2012-12-15

    We utilize a kinetic description to study the dispersion relation of Alfven waves propagating parallelly to the ambient magnetic field in a dusty plasma, taking into account the fluctuation of the charge of the dust particles, which is due to inelastic collisions with electrons and ions. We consider a plasma in which the velocity distribution functions of the plasma particles are modelled as anisotropic kappa distributions, study the dispersion relation for several combinations of the parameters {kappa}{sub Parallel-To} and {kappa}{sub Up-Tack }, and emphasize the effect of the anisotropy of the distributions on the mode coupling which occurs in a dusty plasma, between waves in the branch of circularly polarized waves and waves in the whistler branch.

  12. Prospects for ion temperature measurements in JET by Thomson scattering of submillimetre waves

    International Nuclear Information System (INIS)

    Whitbourn, L.B.

    1975-03-01

    The Thomson scattering of submillimeter waves is envisaged as a possible means for measuring the ion temperature of the JET plasma. The present discussion is principally concerned with the practical limitations imposed to the method by the availability of high power pulsed sources and sensitive detectors and noise due to plasma emission at submillimeter wavelengths (bremsstrahlung and electron cyclotron emission). Coherent scattering from plasma wave (e.g. ion acoustic waves and electron drift waves) with millimeter and submillimeter waves are considered briefly. Further suitable development of lasers and heterodyne detectors would make such measurements possible. A pulsed HCN laser associated with a detectors with a lower heterodyne noise equivalent power could then be used to advantage. For scattering with CH 3 F laser the NEP of a Josephson junction would be adequate because a relatively high level of plasma emission is expected at 496 μm [fr

  13. Stochastic linearization of turbulent dynamics of dispersive waves in equilibrium and non-equilibrium state

    International Nuclear Information System (INIS)

    Jiang, Shixiao W; Lu, Haihao; Zhou, Douglas; Cai, David

    2016-01-01

    Characterizing dispersive wave turbulence in the long time dynamics is central to understanding of many natural phenomena, e.g., in atmosphere ocean dynamics, nonlinear optics, and plasma physics. Using the β -Fermi–Pasta–Ulam nonlinear system as a prototypical example, we show that in thermal equilibrium and non-equilibrium steady state the turbulent state even in the strongly nonlinear regime possesses an effective linear stochastic structure in renormalized normal variables. In this framework, we can well characterize the spatiotemporal dynamics, which are dominated by long-wavelength renormalized waves. We further demonstrate that the energy flux is nearly saturated by the long-wavelength renormalized waves in non-equilibrium steady state. The scenario of such effective linear stochastic dynamics can be extended to study turbulent states in other nonlinear wave systems. (paper)

  14. Cascaded interactions between Raman induced solitons and dispersive waves in photonic crystal fibers at the advanced stage of supercontinuum generation.

    Science.gov (United States)

    Driben, Rodislav; Mitschke, Fedor; Zhavoronkov, Nickolai

    2010-12-06

    The complex mechanism of multiple interactions between solitary and dispersive waves at the advanced stage of supercontinuum generation in photonic crystal fiber is studied in experiment and numerical simulations. Injection of high power negatively chirped pulses near zero dispersion frequency results in an effective soliton fission process with multiple interactions between red shifted Raman solitons and dispersive waves. These interactions may result in relative acceleration of solitons with further collisions between them of quasi-elastic or quasi-plastic kinds. In the spectral domain these processes result in enhancement of certain wavelength regions within the spectrum or development of a new significant band at the long wavelength side of the spectrum.

  15. Integrating a Traveling Wave Tube into an AECR-U ion source

    Energy Technology Data Exchange (ETDEWEB)

    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.

  16. Ab initio calculation atomics ground state wave function for interactions Ion- Atom

    International Nuclear Information System (INIS)

    Shojaee, F.; Bolori zadeh, M. A.

    2007-01-01

    Ab initio calculation atomics ground state wave function for interactions Ion- Atom Atomic wave function expressed in a Slater - type basis obtained within Roothaan- Hartree - Fock for the ground state of the atoms He through B. The total energy is given for each atom.

  17. The Relationship Between Aging and P Wave Dispersion

    Directory of Open Access Journals (Sweden)

    İrfan Barutçu

    2009-12-01

    Full Text Available Objective: Atrial fibrillation (AF, commonly observed in advanced ages, displays striking age dependent increase and increased P wave dispersion (PWD has been shown to be a predictor of AF. In this studywe sought to determine whether P wave duration and PWD increase with aging. Method and Results: Eighty-three elderly subjects (group-I mean age 75±8 years and 40 healthy young subjects (group-II, mean age 37±6 years participated in this study. 12-lead ECG recorded at a paper speed of 50mm/s was obtained from each participant. Maximum (Pmax and minimum P wave duration (Pmin was measured manually with a caliper and the difference between two values was defined asPWD. Pmax and PWD were significantly higher in group-I compared to group-II. (98±8 vs. 93±8 p=0.01, 41±12 vs. 34±13 p=0.002, respectively. Among the elderly population when those with cardiovascular disorders such as hypertension, coronary artery disease and heart failure were excluded, Pmax and PWD were still significantly higher than the young population. (Pmax: 98±7 vs. 93±7, p=0.02 and PWD: 42±11 vs. 34±13, p=0.002. Moreover, on correlation analysis a positive correlation was detected between Pmaxand PWD and aging. (r=0.29, p=0.004; r=0.30, p=0.003 respectively.Conclusion: PWD shows age dependent increase and may be a useful marker for estimation the risk of developing AF seen in advanced ages.

  18. Propagation of ion-acoustic waves in a dusty plasma with non ...

    Indian Academy of Sciences (India)

    [1] to investigate the various salient features of solitary waves in a cold, collisionless ... Moreover, the K-dV theory was applied to ion-acoustic waves by Zakharov ..... to an equation involving term like φ5/2 where the ordinary integration method fails .... Moreover, in this case our attention is drawn to the fact that the rate of.

  19. Mid-infrared frequency comb via coherent dispersive wave generation in silicon nitride nanophotonic waveguides

    Science.gov (United States)

    Guo, Hairun; Herkommer, Clemens; Billat, Adrien; Grassani, Davide; Zhang, Chuankun; Pfeiffer, Martin H. P.; Weng, Wenle; Brès, Camille-Sophie; Kippenberg, Tobias J.

    2018-06-01

    Mid-infrared optical frequency combs are of significant interest for molecular spectroscopy due to the large absorption of molecular vibrational modes on the one hand, and the ability to implement superior comb-based spectroscopic modalities with increased speed, sensitivity and precision on the other hand. Here, we demonstrate a simple, yet effective, method for the direct generation of mid-infrared optical frequency combs in the region from 2.5 to 4.0 μm (that is, 2,500-4,000 cm-1), covering a large fraction of the functional group region, from a conventional and compact erbium-fibre-based femtosecond laser in the telecommunication band (that is, 1.55 μm). The wavelength conversion is based on dispersive wave generation within the supercontinuum process in an unprecedented large-cross-section silicon nitride (Si3N4) waveguide with the dispersion lithographically engineered. The long-wavelength dispersive wave can perform as a mid-infrared frequency comb, whose coherence is demonstrated via optical heterodyne measurements. Such an approach can be considered as an alternative option to mid-infrared frequency comb generation. Moreover, it has the potential to realize compact dual-comb spectrometers. The generated combs also have a fine teeth-spacing, making them suitable for gas-phase analysis.

  20. Electromagnetic ion cyclotron waves stimulated by modest magnetospheric compressions

    Science.gov (United States)

    Anderson, B. J.; Hamilton, D. C.

    1993-01-01

    AMPTE/CCE magnetic field and particle data are used to test the suggestion that increased hot proton temperature anisotropy resulting from convection during magnetospheric compression is responsible for the enhancement in Pc 1 emission via generation of electromagnetic ion cyclotron (EMIC) waves in the dayside outer equatorial magnetosphere. The relative increase in magnetic field is used to gauge the strength of the compression, and an image dipole model is used to estimate the motion of the plasma during compression. Proton data are used to analyze the evolution of the proton distribution and the corresponding changes in EMIC wave activity expected during the compression. It is suggested that enhancements in dynamic pressure pump the energetic proton distributions in the outer magnetosphere, driving EMIC waves. Waves are expected to be generated most readily close to the magnetopause, and transient pressure pulses may be associated with bursts of EMIC waves, which would be observed on the ground in association with ionospheric transient signatures.