Finite Amplitude Electron Plasma Waves in a Cylindrical Waveguide
Juul Rasmussen, Jens
1978-01-01
The nonlinear behaviour of the electron plasma wave propagating in a cylindrical plasma waveguide immersed in an infinite axial magnetic field is investigated using the Krylov-Bogoliubov-Mitropolsky perturbation method, by means of which is deduced the nonlinear Schrodinger equation governing...... the long-time slow modulation of the wave amplitude. From this equation the amplitude-dependent frequency and wavenumber shifts are calculated, and it is found that the electron waves with short wavelengths are modulationally unstable with respect to long-wavelength, low-frequency perturbations...
Breaking of Large Amplitude Electron Plasma Wave in a Maxwellian Plasma
Mukherjee, Arghya
2016-01-01
The determination of maximum possible amplitude of a coherent longitudinal plasma oscillation/wave is a topic of fundamental importance in non-linear plasma physics. The amplitudes of these large amplitude plasma waves is limited by a phenomena called wave breaking which may be induced by several non-linear processes. It was shown by Coffey [T. P. Coffey, Phys. Fluids 14, 1402 (1971)] using a "water-bag" distribution for electrons that, in a warm plasma the maximum electric field amplitude and density amplitude implicitly depend on the electron temperature, known as Coffey's limit. In this paper, the breaking of large amplitude freely running electron plasma wave in a homogeneous warm plasma where electron's velocity distribution is Maxwellian has been studied numerically using 1D Particle in Cell (PIC) simulation method. It is found that Coffey's propagating wave solutions, which was derived using a "water-bag" distribution for electrons, also represent propagating waves in a Maxwellian plasma. Coffey's wave...
Obliquely propagating large amplitude solitary waves in charge neutral plasmas
F. Verheest
2007-01-01
Full Text Available This paper deals in a consistent way with the implications, for the existence of large amplitude stationary structures in general plasmas, of assuming strict charge neutrality between electrons and ions. With the limit of pair plasmas in mind, electron inertia is retained. Combining in a fluid dynamic treatment the conservation of mass, momentum and energy with strict charge neutrality has indicated that nonlinear solitary waves (as e.g. oscillitons cannot exist in electron-ion plasmas, at no angle of propagation with respect to the static magnetic field. Specifically for oblique propagation, the proof has turned out to be more involved than for parallel or perpendicular modes. The only exception is pair plasmas that are able to support large charge neutral solitons, owing to the high degree of symmetry naturally inherent in such plasmas. The nonexistence, in particular, of oscillitons is attributed to the breakdown of the plasma approximation in dealing with Poisson's law, rather than to relativistic effects. It is hoped that future space observations will allow to discriminate between oscillitons and large wave packets, by focusing on the time variability (or not of the phase, since the amplitude or envelope graphs look very similar.
Excitation and evolution of finite-amplitude plasma wave
Hou, Y. W.; Wu, Y. C., E-mail: yican.wu@fds.org.cn [Key Laboratory of Neutronics and Radiation Safety, Institute of Nuclear Energy Safety Technology, Chinese Academy of Sciences, Hefei, Anhui 230031 (China); Chen, M. X. [School of Electronic Science and Applied Physics, Hefei University of Technology, Hefei, Anhui 230009 (China); Yu, M. Y., E-mail: myyu@zju.edu.cn [Institute for Fusion Theory and Simulation and Department of Physics, Zhejiang University, Hangzhou 310027 (China); Institute for Theoretical Physics I, Ruhr University, D-44780 Bochum (Germany); Wu, B. [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui 230031 (China)
2015-12-15
The evolution of a small spatially periodic perturbation in the electron velocity distribution function in collisionless plasma is reconsidered by numerically solving the Vlasov and Poisson equations. The short as well as long time behaviors of the excited oscillations and damping/modulation are followed. In the small but finite-amplitude excited plasma wave, resonant electrons become trapped in the wave potential wells and their motion affects the low-velocity electrons participating in the plasma oscillations, leading to modulation of the latter at an effective trapping frequency. It is found that the phase space of the resonant and low-velocity electrons becomes chaotic, but then self-organization takes place but remains fine-scale chaotic. It is also found that as long as particles are trapped, there is only modulation and no monotonic damping of the excited plasma wave. The modulation period/amplitude increases/decreases as the magnitude of the initial disturbance is reduced. For the initial and boundary conditions used here, linear Landau damping corresponds to the asymptotic limit of the modulation period becoming infinite, or no trapping of the resonant electrons.
Damping and Frequency Shift of Large Amplitude Electron Plasma Waves
Thomsen, Kenneth; Juul Rasmussen, Jens
1983-01-01
The initial evolution of large-amplitude one-dimensional electron waves is investigated by applying a numerical simulation. The initial wave damping is found to be strongly enhanced relative to the linear damping and it increases with increasing amplitude. The temporal evolution of the nonlinear...... damping rate γ(t) shows that it increases with time within the initial phase of propagation, t≲π/ωB (ωB is the bounce frequency), whereafter it decreases and changes sign implying a regrowth of the wave. The shift in the wave frequency δω is observed to be positive for t≲π/ωB; then δω changes sign...
Small amplitude nonlinear electron acoustic solitary waves in weakly magnetized plasma
Dutta, Manjistha; Khan, Manoranjan [Department of Instrumentation Science, Jadavpur University, Kolkata-700 032 (India); Ghosh, Samiran [Department of Applied Mathematics, University of Calcutta, 92, Acharya Prafulla Chandra Road, Kolkata-700 009 (India); Roychoudhury, Rajkumar [Indian Statistical Institute, Kolkata-700 108 (India); Chakrabarti, Nikhil [Saha Institute of Nuclear Physics, 1/AF Bidhannagar Kolkata-700 064 (India)
2013-01-15
Nonlinear propagation of electron acoustic waves in homogeneous, dispersive plasma medium with two temperature electron species is studied in presence of externally applied magnetic field. The linear dispersion relation is found to be modified by the externally applied magnetic field. Lagrangian transformation technique is applied to carry out nonlinear analysis. For small amplitude limit, a modified KdV equation is obtained, the modification arising due to presence of magnetic field. For weakly magnetized plasma, the modified KdV equation possesses stable solitary solutions with speed and amplitude increasing temporally. The solutions are valid upto some finite time period beyond which the nonlinear wave tends to wave breaking.
Plasma Metamaterials for Arbitrary Complex-Amplitude Wave Filters
2013-09-10
y = 120 mm, propagation waves join evanescent waves which are depressed as the position becomes apart from the edge of the metamaterial region...Kik, H. A. Atwater, S. Meltzer , E. Harel, E., B. E. Koel and A. A. Requicha, Nature Mat. 2, 229 (2003). 38 S. A. Maier and H. A. Atwater, J. Appl
Large Amplitude Low Frequency Waves in a Magnetized Nonuniform Electron-Positron-Ion Plasma
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.
Mahmood, S.; Sadiq, Safeer; Haque, Q.; Ali, Munazza Z.
2016-06-01
The obliquely propagating arbitrary amplitude electrostatic wave is studied in a dense magnetized plasma having singly and doubly charged helium ions with nonrelativistic and ultrarelativistic degenerate electrons pressures. The Fermi temperature for ultrarelativistic degenerate electrons described by N. M. Vernet [(Cambridge University Press, Cambridge, 2007), p. 57] is used to define ion acoustic speed in ultra-dense plasmas. The pseudo-potential approach is used to solve the fully nonlinear set of dynamic equations for obliquely propagating electrostatic waves in a dense magnetized plasma containing helium ions. The upper and lower Mach number ranges for the existence of electrostatic solitons are found which depends on the obliqueness of the wave propagation with respect to applied magnetic field and charge number of the helium ions. It is found that only compressive (hump) soliton structures are formed in all the cases and only subsonic solitons are formed for a singly charged helium ions plasma case with nonrelativistic degenerate electrons. Both subsonic and supersonic soliton hump structures are formed for doubly charged helium ions with nonrelativistic degenerate electrons and ultrarelativistic degenerate electrons plasma case containing singly as well as doubly charged helium ions. The effect of propagation direction on the soliton amplitude and width of the electrostatic waves is also presented. The numerical plots are also shown for illustration using dense plasma parameters of a compact star (white dwarf) from literature.
Large amplitude solitary waves in ion-beam plasmas with charged dust impurities
Misra, A P
2011-01-01
The nonlinear propagation of large amplitude dust ion-acoustic (DIA) solitary waves (SWs) in an ion-beam plasma with stationary charged dusts is investigated. For typical plasma parameters relevant for experiments [J. Plasma Phys. \\textbf{60}, 69 (1998)], when the beam speed is larger than the DIA speed ($v_{b0}\\gtrsim1.7c_s$), three stable waves, namely the "fast" and "slow" ion-beam modes and the plasma DIA wave are shown to exist. These modes can propagate as SWs in the beam plasmas. However, in the other regime ($c_s0)$ is found to be limited by a critical value which typically depends on $M$, $v_{b0}$ as well as the ion/beam temperature. The conditions for the existence of DIA solitons are obtained and their properties are analyzed numerically in terms of the system parameters. While the system supports both the compressive and rarefactive large amplitude SWs, the small amplitude solitons exist only of the compressive type. The theoretical results may be useful for observation of soliton excitations in l...
Magneto-Acoustic Waves of Small Amplitude in Optically Thin Quasi-Isentropic Plasmas
Nakariakov, V M; Ibáñez, M H; Nakariakov, Valery M.; Mendoza-Briceno, Cesar A.
1999-01-01
The evolution of quasi-isentropic magnetohydrodynamic waves of small but finite amplitude in an optically thin plasma is analyzed. The plasma is assumed to be initially homogeneous, in thermal equilibrium and with a straight and homogeneous magnetic field frozen in. Depending on the particular form of the heating/cooling function, the plasma may act as a dissipative or active medium for magnetoacoustic waves, while Alfven waves are not directly affected. An evolutionary equation for fast and slow magnetoacoustic waves in the single wave limit, has been derived and solved, allowing us to analyse the wave modification by competition of weakly nonlinear and quasi-isentropic effects. It was shown that the sign of the quasi-isentropic term determines the scenario of the evolution, either dissipative or active. In the dissipative case, when the plasma is first order isentropically stable the magnetoacoustic waves are damped and the time for shock wave formation is delayed. However, in the active case when the plasm...
Ghebache, Siham; Tribeche, Mouloud
2017-10-01
The problem of arbitrary amplitude ion-acoustic solitary waves (IASWs), which accompany electronegative plasmas having positive ions, negative ions, and nonextensive electrons is addressed. The energy integral equation with a new Sagdeev potential is analyzed to examine the existence regions of the IASWs. Different types of electronegative plasmas inspired from the experimental studies of Ichiki et al. (2001) are discussed. Our results show that in such plasmas IASWs, the amplitude and nature of which depend sensitively on the mass and density ratio of the positive and negative ions as well as the q-nonextensive parameter, can exist. Interestingly, one finds that our plasma model supports the coexistence of smooth rarefactive and spiky compressive IASWs. Our results complement and provide new insights on previously published findings on this problem.
Disperson relation of finite amplitude Alfven wave in a relativistic electron- positron plasma
Hada, T; Muñoz, V; Hada, Tohru; Matsukiyo, Shuichi; Munoz, Victor
2004-01-01
The linear dispersion relation of a finite amplitude, parallel, circularly polarized Alfv\\'en wave in a relativistic electron-positron plasma is derived. In the nonrelativistic regime, the dispersion relation has two branches, one electromagnetic wave, with a low frequency cutoff at $\\sqrt{1+2\\omega_p^2/\\Omega_p^2}$ (where $\\omega_p=(4\\pi n e^2/m)^{1/2}$ is the electron/positron plasma frequency), and an Alfv\\'en wave, with high frequency cutoff at the positron gyrofrequency $\\Omega_p$. There is only one forward propagating mode for a given frequency. However, due to relativistic effects, there is no low frequency cutoff for the electromagnetic branch, and there appears a critical wave number above which the Alfv\\'en wave ceases to exist. This critical wave number is given by $ck_c/\\Omega_p=a/\\eta$, where $a=\\omega_p^2/\\Omega_p^2$ and $\\eta$ is the ratio between the Alfv\\'en wave magnetic field amplitude and the background magnetic field. In this case, for each frequency in the Alfv\\'en branch, two additional...
Finite-amplitude shear-Alfv\\'en waves do not propagate in weakly magnetized collisionless plasmas
Squire, J; Schekochihin, A A
2016-01-01
It is shown that low-collisionality plasmas cannot support linearly polarized shear-Alfv\\'en fluctuations above a critical amplitude $\\delta B_{\\perp}/B_{0} \\sim \\beta^{\\,-1/2}$, where $\\beta$ is the ratio of thermal to magnetic pressure. Above this cutoff, a developing fluctuation will generate a pressure anisotropy that is sufficient to destabilize itself through the parallel firehose instability. This causes the wave frequency to approach zero, interrupting the fluctuation before any oscillation. The magnetic field lines rapidly relax into a sequence of angular zig-zag structures. Such a restrictive bound on shear-Alfv\\'en-wave amplitudes has far-reaching implications for the physics of magnetized turbulence in the high-$\\beta$ conditions prevalent in many astrophysical plasmas, as well as for the solar wind at $\\sim 1 \\mathrm{AU}$ where $\\beta \\gtrsim 1$.
Small amplitude electron acoustic solitary waves in a magnetized superthermal plasma
Devanandhan, S.; Singh, S. V.; Lakhina, G. S.; Bharuthram, R.
2015-05-01
The propagation of electron acoustic solitary waves in a magnetized plasma consisting of fluid cold electrons, electron beam and superthermal hot electrons (obeying kappa velocity distribution function) and ion is investigated in a small amplitude limit using reductive perturbation theory. The Korteweg-de-Vries-Zakharov-Kuznetsov (KdV-ZK) equation governing the dynamics of electron acoustic solitary waves is derived. The solution of the KdV-ZK equation predicts the existence of negative potential solitary structures. The new results are: (1) increase of either the beam speed or temperature of beam electrons tends to reduce both the amplitude and width of the electron acoustic solitons, (2) the inclusion of beam speed and temperature pushes the allowed Mach number regime upwards and (3) the soliton width maximizes at certain angle of propagation (αm) and then decreases for α >αm . In addition, increasing the superthermality of the hot electrons also results in reduction of soliton amplitude and width. For auroral plasma parameters observed by Viking, the obliquely propagating electron-acoustic solitary waves have electric field amplitudes in the range (7.8-45) mV/m and pulse widths (0.29-0.44) ms. The Fourier transform of these electron acoustic solitons would result in a broadband frequency spectra with peaks near 2.3-3.5 kHz, thus providing a possible explanation of the broadband electrostatic noise observed during the Burst a.
Rouhani, M. R.; Akbarian, A.; Mohammadi, Z. [Department of Physics, Alzahra University, P. O. Box 1993891176, Tehran (Iran, Islamic Republic of)
2013-08-15
The behavior of quantum dust ion acoustic soliton and shocks in a plasma including inertialess quantum electrons and positrons, classical cold ions, and stationary negative dust grains are studied, using arbitrary amplitude approach. The effect of dissipation due to viscosity of ions is taken into account. The numerical analysis of Sagdeev potential for small value of quantum diffraction parameter (H) shows that for chosen plasma, only compressive solitons can exist and the existence domain of this type of solitons is decreased by increasing dust density (d). Additionally, the possibility of propagation of both subsonic and supersonic compressive solitons is investigated. It is shown that there is a critical dust density above which only supersonic solitons are observed. Moreover, increasing d leads to a reduction in the existence domain of compressive solitons and the possibility of propagation of rarefactive soliton is provided. So, rarefactive solitons are observed only due to the presence of dust particles in this model quantum plasma. Furthermore, numerical solution of governed equations for arbitrary amplitude shock waves has been investigated. It is shown that only compressive large amplitude shocks can propagate. Finally, the effects of plasma parameters on these structures are investigated. This research will be helpful in understanding the properties of dense astrophysical (i.e., white dwarfs and neutron stars) and laboratory dusty plasmas.
Arbitrary amplitude kinetic Alfven solitary waves in two temperature electron superthermal plasma
Singh, Manpreet; Singh Saini, Nareshpal; Ghai, Yashika
2016-07-01
Through various satellite missions it is observed that superthermal velocity distribution for particles is more appropriate for describing space and astrophysical plasmas. So it is appropriate to use superthermal distribution, which in the limiting case when spectral index κ is very large ( i.e. κ→∞), shifts to Maxwellian distribution. Two temperature electron plasmas have been observed in auroral regions by FAST satellite mission, and also by GEOTAIL and POLAR satellite in the magnetosphere. Kinetic Alfven waves arise when finite Larmor radius effect modifies the dispersion relation or characteristic perpendicular wavelength is comparable to electron inertial length. We have studied the kinetic Alfven waves (KAWs) in a plasma comprising of positively charged ions, superthermal hot electrons and Maxwellian distributed cold electrons. Sagdeev pseudo-potential has been employed to derive an energy balance equation. The critical Mach number has been determined from the expression of Sagdeev pseudo-potential to see the existence of solitary structures. It is observed that sub-Alfvenic compressive solitons and super-Alfvenic rarefactive solitons exist in this plasma model. It is also observed that various parameters such as superthermality of hot electrons, relative concentration of cold and hot electron species, Mach number, plasma beta, ion to cold electron temperature ratio and ion to hot electron temperature ratio have significant effect on the amplitude and width of the KAWs. Findings of this investigation may be useful to understand the dynamics of coherent non-linear structures (i.e. KAWs) in space and astrophysical plasmas.
Mode conversion of large-amplitude electromagnetic waves in relativistic critical density plasmas
Pesch, T.C.; Kull, H.J. [Aachen Univ., Institute of Theoretical Physics A, RWTH (Germany)
2009-01-15
The propagation of linearly polarized large-amplitude electromagnetic waves in critical density plasmas is studied in the framework of the Akiezer-Polovin model. A new mechanism of mode conversion is presented. The well-known periodic solutions are generalized to quasiperiodic solutions taking into account additional electrostatic oscillations. Nearly periodic circle-like solutions are found to be stabilized by intrinsic mode coupling whereas for nearly periodic eight-like solutions an effective mode conversion mechanism is discovered. Finally, the modulation timescales are considered. (authors)
Amina, M.; Ema, S. A.; Mamun, A. A.
2017-06-01
Theoretical investigation is carried out for understanding the properties of nonlinear dust-acoustic (DA) waves in an unmagnetized dusty plasma whose constituents are massive, micron-sized, positive and negatively charged inertial dust grains along with q (nonextensive) distributed electrons and ions. The reductive perturbation method is employed in order to derive two types of nonlinear dynamical equations, namely, Burgers equation and modified Gardner equation (Gardner equation with dissipative term). They are also numerically analyzed to investigate the basic features (viz., polarity, amplitude, width, etc.) of shock waves and double layers. It has been observed that the effects of nonextensivity, opposite polarity charged dust grains, and different dusty plasma parameters have significantly modified the fundamental properties of shock waves and double layers. The results of this investigation may be used for researches of the nonlinear wave propagation in laboratory and space plasmas.
Amplitude limits and nonlinear damping of shear-Alfvén waves in high-beta low-collisionality plasmas
Squire, J.; Schekochihin, A. A.; Quataert, E.
2017-05-01
This work, which extends Squire et al (Astrophys. J. Lett. 2016 830 L25), explores the effect of self-generated pressure anisotropy on linearly polarized shear-Alfvén fluctuations in low-collisionality plasmas. Such anisotropies lead to stringent limits on the amplitude of magnetic perturbations in high-β plasmas, above which a fluctuation can destabilize itself through the parallel firehose instability. This causes the wave frequency to approach zero, ‘interrupting’ the wave and stopping its oscillation. These effects are explored in detail in the collisionless and weakly collisional ‘Braginskii’ regime, for both standing and traveling waves. The focus is on simplified models in one dimension, on scales much larger than the ion gyroradius. The effect has interesting implications for the physics of magnetized turbulence in the high-β conditions that are prevalent in many astrophysical plasmas.
Small amplitude Kinetic Alfven waves in a superthermal electron-positron-ion plasma
Adnan, Muhammad; Mahmood, Sahahzad; Qamar, Anisa; Tribeche, Mouloud
2016-11-01
We are investigating the propagating properties of coupled Kinetic Alfven-acoustic waves in a low beta plasma having superthermal electrons and positrons. Using the standard reductive perturbation method, a nonlinear Korteweg-de Vries (KdV) type equation is derived which describes the evolution of Kinetic Alfven waves. It is found that nonlinearity and Larmor radius effects can compromise and give rise to solitary structures. The parametric role of superthermality and positron content on the characteristics of solitary wave structures is also investigated. It is found that only sub-Alfvenic and compressive solitons are supported in the present model. The present study may find applications in a low β electron-positron-ion plasma having superthermal electrons and positrons.
Hafez, M. G.; Talukder, M. R.; Ali, M. Hossain
2016-01-01
The theoretical and numerical studies have been investigated on the nonlinear propagation of electrostatic ion-acoustic waves (IAWs) in an un-magnetized Thomas-Fermi plasma system consisting of electron, positrons, and positive ions for both of ultra-relativistic and non-relativistic degenerate electrons. Korteweg-de Vries (K-dV) equation is derived from the model equations by using the well-known reductive perturbation method. This equation is solved by employing the generalized Riccati equation mapping method. The hyperbolic functions type solutions to the K-dV equation are only considered for describing the effect of plasma parameters on the propagation of electrostatic IAWs for both of ultra-relativistic and non-relativistic degenerate electrons. The obtained results may be helpful in proper understanding the features of small but finite amplitude localized IAWs in degenerate plasmas and provide the mathematical foundation in plasma physics.
Martínez-Gómez, David; Soler, Roberto; Terradas, Jaume
2017-03-01
The presence of neutral species in a plasma has been shown to greatly affect the properties of magnetohydrodynamic waves. For instance, the interaction between ions and neutrals through momentum transfer collisions causes the damping of Alfvén waves and alters their oscillation frequency and phase speed. When the collision frequencies are larger than the frequency of the waves, single-fluid magnetohydrodynamic approximations can accurately describe the effects of partial ionization, since there is a strong coupling between the various species. However, at higher frequencies, the single-fluid models are not applicable and more complex approaches are required. Here, we use a five-fluid model with three ionized and two neutral components, which takes into consideration Hall’s current and Ohm’s diffusion in addition to the friction due to collisions between different species. We apply our model to plasmas composed of hydrogen and helium, and allow the ionization degree to be arbitrary. By analyzing the corresponding dispersion relation and numerical simulations, we study the properties of small-amplitude perturbations. We discuss the effect of momentum transfer collisions on the ion-cyclotron resonances and compare the importance of magnetic resistivity, and ion–neutral and ion–ion collisions on the wave damping at various frequency ranges. Applications to partially ionized plasmas of the solar atmosphere are performed.
Martínez-Gómez, David; Terradas, Jaume
2016-01-01
Ideal MHD provides an accurate description of low-frequency Alfv\\'en waves in fully ionized plasmas. However, higher frequency waves in many plasmas of the solar atmosphere cannot be correctly described by ideal MHD and a more accurate model is required. Here, we study the properties of small-amplitude incompressible perturbations in both the low and the high frequency ranges in plasmas composed of several ionized species. We use a multi-fluid approach and take into account the effects of collisions between ions and the inclusion of Hall's term in the induction equation. Through the analysis of the corresponding dispersion relations and numerical simulations we check that at high frequencies ions of different species are not as strongly coupled as in the low frequency limit. Hence, they cannot be treated as a single fluid. In addition, elastic collisions between the distinct ionized species are not negligible for high frequency waves since an appreciable damping is obtained. Furthermore, Coulomb collisions be...
Swanson, DG
1989-01-01
Plasma Waves discusses the basic development and equations for the many aspects of plasma waves. The book is organized into two major parts, examining both linear and nonlinear plasma waves in the eight chapters it encompasses. After briefly discussing the properties and applications of plasma wave, the book goes on examining the wave types in a cold, magnetized plasma and the general forms of the dispersion relation that characterize the waves and label the various types of solutions. Chapters 3 and 4 analyze the acoustic phenomena through the fluid model of plasma and the kinetic effects. Th
Electron Acoustic Waves and the Search for a Truly Self-Consistent Large-Amplitude Plasma Response
Johnston, Tudor; Afeyan, Bedros
2003-10-01
We examine some theoretical nonlinear Vlasov work invoked in connection with recent laser-plasma experiments [1] on Electron Acoustic Waves and their stimulated scatter (SEAS). Earlier work discussed [2-5] is then related to more recent theory [6] used to interpret [1]. All this [2-6] is then related the recent Vlasov-Poisson findings of Afeyan et al. [7] on Kinetic Electrostatic Electron Nonlinear (KEEN) waves. (Part of this work was performed under the auspices of the U.S. Department of Energy under grant number DE-FG03-NA00059.) [1] D.S. Montgomery et al., Phys. Rev. Lett. 87, 155001 (2001), Phys. Plasmas 9, 2311(2002). [2] I.B. Bernstein et al., Phys.Rev. 108, 546 (1957). [3] W.P. Allis, paper no. 3 pp. 21-42, in In Honor of Philip M. Morse, ed. H. Feshbach and K. Ingard, MIT Press, Cambridge, MA, (1969). (Source for V.B. Krapchev and A.K. Ram, Phys. Rev. A, 22, 1229 (1980)). [4] H. Schamel, Phys. Scr. 20, 336 (1979), Phys. Rep. 140, 161 (1986), Phys. Plasmas 7, 4831 (2000). [5] J.P. Holloway and J.J. Dorning, Phys. Lett. A 138, 279 (1989) and Phys. Rev. A 44, 3856 (1991). [6] H. A. Rose and D. A. Russell, Phys. Plasmas 8, 4784 (2001). [7] B. B. Afeyan et al., "Optical Mixing Generated Kinetic Electrostatic Electron Nonlinear (KEEN) Waves", manuscript in preparation and poster at this conference.
Remya, B.; Reddy, R. V.; Lakhina, G. S. [Indian Institute of Geomagnetism, Kalamboli Highway, New Panvel, Navi Mumbai, Maharashtra (India); Tsurutani, B. T.; Falkowski, B. J. [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Echer, E. [Instituto Nacional de Pesquisas Espaciais (INPE), Avenida Astronautas, 1758, P.O. Box 515, Sao Jose dos Campos, SP (Brazil); Glassmeier, K.-H., E-mail: remyaphysics@gmail.com [Institute for Geophysics and Extraterrestrial Physics (IGEP), Mendelssohnstr.3, D-38106, Braunschweig (Germany)
2014-09-20
During 1999 August 18, both Cassini and WIND were in the Earth's magnetosheath and detected transverse electromagnetic waves instead of the more typical mirror-mode emissions. The Cassini wave amplitudes were as large as ∼14 nT (peak to peak) in a ∼55 nT ambient magnetic field B {sub 0}. A new method of analysis is applied to study these waves. The general wave characteristics found were as follows. They were left-hand polarized and had frequencies in the spacecraft frame (f {sub scf}) below the proton cyclotron frequency (f{sub p} ). Waves that were either right-hand polarized or had f {sub scf} > f{sub p} are shown to be consistent with Doppler-shifted left-hand waves with frequencies in the plasma frame f{sub pf} < f{sub p} . Thus, almost all waves studied are consistent with their being electromagnetic proton cyclotron waves. Most of the waves (∼55%) were found to be propagating along B {sub 0} (θ{sub kB{sub 0}}<30{sup ∘}), as expected from theory. However, a significant fraction of the waves were found to be propagating oblique to B {sub 0}. These waves were also circularly polarized. This feature and the compressive ([B {sub max} – B {sub min}]/B {sub max}, where B {sub max} and B {sub min} are the maximum and minimum field magnitudes) nature (ranging from 0.27 to 1.0) of the waves are noted but not well understood at this time. The proton cyclotron waves were shown to be quasi-coherent, theoretically allowing for rapid pitch-angle transport of resonant protons. Because Cassini traversed the entire subsolar magnetosheath and WIND was in the dusk-side flank of the magnetosheath, it is surmised that the entire region was filled with these waves. In agreement with past theory, it was the exceptionally low plasma β (0.35) that led to the dominance of the proton cyclotron wave generation during this interval. A high-speed solar wind stream ((V{sub sw} ) = 598 km s{sup –1}) was the source of this low-β plasma.
Amplitude Equations for Electrostatic Waves multiple species
Crawford, J D; Crawford, John David; Jayaraman, Anandhan
1997-01-01
The amplitude equation for an unstable electrostatic wave is analyzed using an expansion in the mode amplitude $A(t)$. In the limit of weak instability, i.e. $\\gamma\\to 0^+$ where $\\gamma$ is the linear growth rate, the nonlinear coefficients are singular and their singularities predict the dependence of $A(t)$ on $\\gamma$. Generically the scaling $|A(t)|=\\gamma^{5/2}r(\\gamma t)$ as orders. This result predicts the electric field scaling $|E_k|\\sim\\gamma^{5/2}$ will hold universally for these instabilities (including beam-plasma and two-stream configurations) throughout the dynamical evolution and in the time-asymptotic state. In exceptional cases, such as infinitely massive ions, the coefficients are less singular and the more familiar trapping scaling $|E_k|\\sim\\gamma^2$ is recovered.
An amplitude modulated radio frequency plasma generator
Lei, Fan; Li, Xiaoping; Liu, Yanming; Liu, Donglin; Yang, Min; Xie, Kai; Yao, Bo
2017-04-01
A glow discharge plasma generator and diagnostic system has been developed to study the effects of rapidly variable plasmas on electromagnetic wave propagation, mimicking the plasma sheath conditions encountered in space vehicle reentry. The plasma chamber is 400 mm in diameter and 240 mm in length, with a 300-mm-diameter unobstructed clear aperture. Electron densities produced are in the mid 1010 electrons/cm3. An 800 W radio frequency (RF) generator is capacitively coupled through an RF matcher to an internally cooled stainless steel electrode to form the plasma. The RF power is amplitude modulated by a waveform generator that operates at different frequencies. The resulting plasma contains electron density modulations caused by the varying power levels. A 10 GHz microwave horn antenna pair situated on opposite sides of the chamber serves as the source and detector of probe radiation. The microwave power feed to the source horn is split and one portion is sent directly to a high-speed recording oscilloscope. On mixing this with the signal from the pickup horn antenna, the plasma-induced phase shift between the two signals gives the path-integrated electron density with its complete time dependent variation. Care is taken to avoid microwave reflections and extensive shielding is in place to minimize electronic pickup. Data clearly show the low frequency modulation of the electron density as well as higher harmonics and plasma fluctuations.
Brodin, G., E-mail: gert.brodin@physics.umu.se [Department of Physics, Umeå University, SE-901 87 Umeå (Sweden); Stenflo, L. [Department of Physics, Linköping University, SE-581 83 Linköping (Sweden)
2017-03-18
Considering a class of solutions where the density perturbations are functions of time, but not of space, we derive a new exact large amplitude wave solution for a cold uniform electron plasma. This result illustrates that most simple analytical solutions can appear even if the density perturbations are large. - Highlights: • The influence of large amplitude electromagnetic waves on electrostatic oscillations is found. • A generalized Mathieu equation is derived. • Anharmonic wave profiles are computed numerically.
Relativistic spherical plasma waves
Bulanov, S. S.; Maksimchuk, A.; Schroeder, C. B.; Zhidkov, A. G.; Esarey, E.; Leemans, W. P.
2012-02-01
Tightly focused laser pulses that diverge or converge in underdense plasma can generate wake waves, having local structures that are spherical waves. Here we study theoretically and numerically relativistic spherical wake waves and their properties, including wave breaking.
Magnetoresistive waves in plasmas
Felber, F. S.; Hunter, R. O., Jr.; Pereira, N. R.; Tajima, T.
1982-10-01
The self-generated magnetic field of a current diffusing into a plasma between conductors can magnetically insulate the plasma. Propagation of magnetoresistive waves in plasmas is analyzed. Applications to plasma opening switches are discussed.
Dudok de Wit, T; Dunlop, M; Luehr, H
1999-01-01
A framework is described for estimating Linear growth rates and spectral energy transfers in turbulent wave-fields using two-point measurements. This approach, which is based on Volterra series, is applied to dual satellite data gathered in the vicinity of the Earth's bow shock, where Short Large Amplitude Magnetic Structures (SLAMS) supposedly play a leading role. The analysis attests the dynamic evolution of the SLAMS and reveals an energy cascade toward high-frequency waves.
Undamped electrostatic plasma waves
Valentini, F; Califano, F; Pegoraro, F; Veltri, P; Morrison, P J; O'Neil, T M
2015-01-01
Electrostatic waves in a collision-free unmagnetized plasma of electrons with fixed ions are investigated for electron equilibrium velocity distribution functions that deviate slightly from Maxwellian. Of interest are undamped waves that are the small amplitude limit of nonlinear excitations, such as electron acoustic waves (EAWs). A deviation consisting of a small plateau, a region with zero velocity derivative over a width that is a very small fraction of the electron thermal speed, is shown to give rise to new undamped modes, which here are named {\\it corner modes}. The presence of the plateau turns off Landau damping and allows oscillations with phase speeds within the plateau. These undamped waves are obtained in a wide region of the $(k,\\omega_{_R})$ plane ($\\omega_{_R}$ being the real part of the wave frequency and $k$ the wavenumber), away from the well-known `thumb curve' for Langmuir waves and EAWs based on the Maxwellian. Results of nonlinear Vlasov-Poisson simulations that corroborate the existenc...
Artemyev, A. V., E-mail: ante0226@gmail.com [Space Research Institute, RAS, Moscow (Russian Federation); Mourenas, D.; Krasnoselskikh, V. V. [LPC2E/CNRS - University of Orleans, Orleans (France); Agapitov, O. V. [Space Sciences Laboratory, University of California, Berkeley, California 94720 (United States)
2015-06-15
In this paper, we study relativistic electron scattering by fast magnetosonic waves. We compare results of test particle simulations and the quasi-linear theory for different spectra of waves to investigate how a fine structure of the wave emission can influence electron resonant scattering. We show that for a realistically wide distribution of wave normal angles θ (i.e., when the dispersion δθ≥0.5{sup °}), relativistic electron scattering is similar for a wide wave spectrum and for a spectrum consisting in well-separated ion cyclotron harmonics. Comparisons of test particle simulations with quasi-linear theory show that for δθ>0.5{sup °}, the quasi-linear approximation describes resonant scattering correctly for a large enough plasma frequency. For a very narrow θ distribution (when δθ∼0.05{sup °}), however, the effect of a fine structure in the wave spectrum becomes important. In this case, quasi-linear theory clearly fails in describing accurately electron scattering by fast magnetosonic waves. We also study the effect of high wave amplitudes on relativistic electron scattering. For typical conditions in the earth's radiation belts, the quasi-linear approximation cannot accurately describe electron scattering for waves with averaged amplitudes >300 pT. We discuss various applications of the obtained results for modeling electron dynamics in the radiation belts and in the Earth's magnetotail.
Brodin, G.; Stenflo, L.
2017-03-01
Considering a class of solutions where the density perturbations are functions of time, but not of space, we derive a new exact large amplitude wave solution for a cold uniform electron plasma. This result illustrates that most simple analytical solutions can appear even if the density perturbations are large.
Organizing Filament of Small Amplitude Scroll Waves
ZHOU TianShou; ZHANG SuoChun
2001-01-01
We theoretically analyze the organizing filament of small amplitude scroll waves in general excitable media by perturbation method and explicitly give the expressions of coefficients in Keener theory. In particular for the excitable media with equal diffusion, we obtain a close system for the motion of the filament. With an example of the Oregonator model, our results are in good agreement with those simulated by Winfree.``
Chaotic ion motion in magnetosonic plasma waves
Varvoglis, H.
1984-01-01
The motion of test ions in a magnetosonic plasma wave is considered, and the 'stochasticity threshold' of the wave's amplitude for the onset of chaotic motion is estimated. It is shown that for wave amplitudes above the stochasticity threshold, the evolution of an ion distribution can be described by a diffusion equation with a diffusion coefficient D approximately equal to 1/v. Possible applications of this process to ion acceleration in flares and ion beam thermalization are discussed.
Geyer, Anna
2016-01-01
Following a general principle introduced by Ehrnstr\\"{o}m et.al. we prove that for an equation modeling the free surface evolution of moderate amplitude waves in shallow water, all symmetric waves are traveling waves.
Geyer, Anna
2016-01-01
Following a general principle introduced by Ehrnstr\\"{o}m et.al. we prove that for an equation modeling the free surface evolution of moderate amplitude waves in shallow water, all symmetric waves are traveling waves.
Relativistic spherical plasma waves
Bulanov, S S; Schroeder, C B; Zhidkov, A G; Esarey, E; Leemans, W P
2011-01-01
Tightly focused laser pulses as they diverge or converge in underdense plasma can generate wake waves, having local structures that are spherical waves. Here we report on theoretical study of relativistic spherical wake waves and their properties, including wave breaking. These waves may be suitable as particle injectors or as flying mirrors that both reflect and focus radiation, enabling unique X-ray sources and nonlinear QED phenomena.
Lominadze, D G
2013-01-01
Cyclotron Waves in Plasma is a four-chapter text that covers the basic physical concepts of the theory of cyclotron waves and cyclotron instabilities, brought about by the existence of steady or alternating plasma currents flowing perpendicular to the magnetic field.This book considers first a wide range of questions associated with the linear theory of cyclotron oscillations in equilibrium plasmas and in electron plasmas in metals and semiconductors. The next chapter deals with the parametric excitation of electron cyclotron oscillations in plasma in an alternating electric field. A chapter f
Gurnett, Donald A.
1995-01-01
An overview is given of spacecraft observations of plasma waves in the solar system. In situ measurements of plasma phenomena have now been obtained at all of the planets except Mercury and Pluto, and in the interplanetary medium at heliocentric radial distances ranging from 0.29 to 58 AU. To illustrate the range of phenomena involved, we discuss plasma waves in three regions of physical interest: (1) planetary radiation belts, (2) planetary auroral acceleration regions and (3) the solar wind. In each region we describe examples of plasma waves that are of some importance, either due to the role they play in determining the physical properties of the plasma, or to the unique mechanism involved in their generation.
Colliding solitary waves in quark gluon plasmas
Rafiei, Azam; Javidan, Kurosh
2016-09-01
We study the head-on collision of propagating waves due to perturbations in quark gluon plasmas. We use the Massachusetts Institute of Technology bag model, hydrodynamics equation, and suitable equation of state for describing the time evolution of such localized waves. A nonlinear differential equation is derived for the propagation of small amplitude localized waves using the reductive perturbation method. We show that these waves are unstable and amplitude of the left-moving (right-moving) wave increases (decreases) after the collision, and so they reach the borders of a quark gluon plasma fireball with different amplitudes. Indeed we show that such arrangements are created because of the geometrical symmetries of the medium.
Turbulence beneath finite amplitude water waves
Beya, J.F. [Universidad de Valparaiso, Escuela de Ingenieria Civil Oceanica, Facultad de Ingenieria, Valparaiso (Chile); The University of New South Wales, Water Research Laboratory, School of Civil and Environmental Engineering, Sydney, NSW (Australia); Peirson, W.L. [The University of New South Wales, Water Research Laboratory, School of Civil and Environmental Engineering, Sydney, NSW (Australia); Banner, M.L. [The University of New South Wales, School of Mathematics and Statistics, Sydney, NSW (Australia)
2012-05-15
Babanin and Haus (J Phys Oceanogr 39:2675-2679, 2009) recently presented evidence of near-surface turbulence generated below steep non-breaking deep-water waves. They proposed a threshold wave parameter a {sup 2}{omega}/{nu} = 3,000 for the spontaneous occurrence of turbulence beneath surface waves. This is in contrast to conventional understanding that irrotational wave theories provide a good approximation of non-wind-forced wave behaviour as validated by classical experiments. Many laboratory wave experiments were carried out in the early 1960s (e.g. Wiegel 1964). In those experiments, no evidence of turbulence was reported, and steep waves behaved as predicted by the high-order irrotational wave theories within the accuracy of the theories and experimental techniques at the time. This contribution describes flow visualisation experiments for steep non-breaking waves using conventional dye techniques in the wave boundary layer extending above the wave trough level. The measurements showed no evidence of turbulent mixing up to a value of a {sup 2}{omega}/{nu} = 7,000 at which breaking commenced in these experiments. These present findings are in accord with the conventional understandings of wave behaviour. (orig.)
Parametric instabilities of large amplitude Alfven waves with obliquely propagating sidebands
Vinas, A. F.; Goldstein, M. L.
1992-01-01
This paper presents a brief report on properties of the parametric decay and modulational, filamentation, and magnetoacoustic instabilities of a large amplitude, circularly polarized Alfven wave. We allow the daughter and sideband waves to propagate at an arbitrary angle to the background magnetic field so that the electrostatic and electromagnetic characteristics of these waves are coupled. We investigate the dependance of these instabilities on dispersion, plasma/beta, pump wave amplitude, and propagation angle. Analytical and numerical results are compared with numerical simulations to investigate the full nonlinear evolution of these instabilities.
Kinematics and amplitude evolution of global coronal extreme ultraviolet waves
Ting Li; Jun Zhang; Shu-Hong Yang; Wei Liu
2012-01-01
With the observations of the Solar-Terrestrial Relations Observatory (STEREO) and the Solar Dynamics Observatory (SDO),we analyze in detail the kinematics of global coronal waves together with their intensity amplitudes (so-called "perturbation profiles").We use a semi-automatic method to investigate the perturbation profiles of coronal waves.The location and amplitude of the coronal waves are calculated over a 30° sector on the sphere,where the wave signal is strongest.The position with the strongest perturbation at each time is considered as the location of the wave front.In all four events,the wave velocities vary with time for most of their lifetime,up to 15 min,while in the event observed by the Atmospheric Imaging Assembly there is an additional early phase with a much higher velocity.The velocity varies greatly between different waves from 216 to 440 km s-1.The velocity of the two waves initially increases,subsequently decreases,and then increases again.Two other waves show a deceleration followed by an acceleration.Three categories of amplitude evolution of global coronal waves are found for the four events.The first is that the amplitude only shows a decrease.The second is that the amplitude initially increases and then decreases,and the third is that the amplitude shows an orderly increase,a decrease,an increase again and then a decrease.All the extreme ultraviolet waves show a decrease in amplitude while propagating farther away,probably because the driver of the global coronal wave (coronal mass ejection) is moving farther away from the solar surface.
Surface Wave Amplitude Anomalies in the Western United States
Eddy, C.; Ekstrom, G.
2011-12-01
We determine maps of local surface wave amplitude factors across the Western United States for Rayleigh and Love waves at discrete periods between 25 and 125s. Measurements of raw amplitude anomalies are made from data recorded at 1161 USArray stations for minor arc arrivals of earthquakes with Mw>5.5 occurring between 2006 and 2010. We take the difference between high-quality amplitude anomaly measurements for events recorded on station pairs less than 2 degrees apart. The mean of these differences for each station pair is taken as the datum. Surface wave amplitudes are controlled by four separate mechanisms: focusing due to elastic structure, attenuation due to anelastic structure, source effects, and receiver effects. By taking the mean of the differences of amplitude anomalies for neighboring stations, we reduce the effects of focusing, attenuation, and the seismic source, thus isolating amplitude anomalies due to near-receiver amplitude effects. We determine local amplitude factors for each USArray station by standard linear inversion of the differential data set. The individual station amplitude factors explain the majority of the variance of the data. For example, derived station amplitude factors for 50s Rayleigh waves explain 92% of the variance of the data. We explore correlations between derived station amplitude factors and local amplitude factors predicted by crust and upper mantle models. Maps of local amplitude factors show spatial correlation with topography and geologic structures in the Western United States, particularly for maps derived from Rayleigh wave amplitude anomalies. A NW-SE trending high in amplitude factors in Eastern California is evident in the 50s map, corresponding to the location of the Sierra Nevada Mountains. High amplitude factors are observed in Colorado and New Mexico in the 50s-125s maps in the location of the highest peaks of the Rocky Mountains. High amplitude factors are also seen in Southern Idaho and Eastern Wyoming in
Amplitude equations for coupled electrostatic waves in the limit of weak instability
Crawford, J D; Crawford, John David; Knobloch, Edgar
1997-01-01
We consider the simplest instabilities involving multiple unstable electrostatic plasma waves corresponding to four-dimensional systems of mode amplitude equations. In each case the coupled amplitude equations are derived up to third order terms. The nonlinear coefficients are singular in the limit in which the linear growth rates vanish together. These singularities are analyzed using techniques developed in previous studies of a single unstable wave. In addition to the singularities familiar from the one mode problem, there are new singularities in coefficients coupling the modes. The new singularities are most severe when the two waves have the same linear phase velocity and satisfy the spatial resonance condition $k_2=2k_1$. As a result the short wave mode saturates at a dramatically smaller amplitude than that predicted for the weak growth rate regime on the basis of single mode theory. In contrast the long wave mode retains the single mode scaling. If these resonance conditions are not satisfied both mo...
Collapse of nonlinear electron plasma waves in a plasma layer
Grimalsky, V.; Koshevaya, S.; Rapoport, Yu; Kotsarenko, A.
2016-10-01
The excitation of nonlinear electron plasma waves in the plasma layer is investigated theoretically. This excitation is realized by means of initial oscillatory perturbations of the volume electron concentration or by initial oscillatory distributions of the longitudinal electron velocity. The amplitudes of the initial perturbations are small and the manifestation of the volume nonlinearity is absent. When the amplitudes of the initial perturbations exceed some thresholds, the values of the electron concentration near the plasma boundary increase catastrophically. The maxima of the electron concentration reach extremely high magnitudes, and sharp peaks in the electron concentration occur, which are localized both in the longitudinal and transverse directions. This effect is interpreted as wave collapse near the plasma boundary.
Turbulent Flow over Small Amplitude Solid Waves
1984-01-01
7. Annubar flow meter 8. Butterfly throttling valve 9. Removable blanking plate 10. Diaphragm valve 11. Small pump 12. By pass diaphragm valve...monitored by using an annubar connected to either a mercury or mirriam oil filled manometer. (b) Test Section 2 a A wave with a ratio of 0.014
Calibration procedure for plasma polarimetry based on the complex amplitude ratio measurements
Bieg, Bohdan, E-mail: b.bieg@am.szczecin.pl [Maritime University, Szczecin (Poland); Kravtsov, Yury A.; Cieplik, Marek [Maritime University, Szczecin (Poland)
2013-10-15
New methodology for plasma polarimeters calibration is suggested, based on the complex amplitude ratio (CAR) measurements. This methodology reduces calibration to determination of three complex parameters of transfer matrix, characterizing polarization changes in optical system. Having obtained transfer matrix, full characteristic of the optic system could be obtained: eigenstates, phase shift and relative attenuation of the slow and fast wave. Polarization state of the sounding electromagnetic wave after the plasma is determined from the measured complex amplitude ratio by simple inversion of transfer matrix. Calibration procedure under discussion is simpler, more transparent and reliable than traditional procedures, using Stokes vector technique or angular parameters of polarization ellipse.
Shoaling Large Amplitude Internal Solitary Waves in a Laboratory Tank
Allshouse, Michael; Larue, Conner; Swinney, Harry
2014-11-01
The shoaling of internal solitary waves onto the continental shelf can change both the wave dynamics and the state of the environment. Previous observations have demonstrated that these waves can trap fluid and transport it over long distances. Through the use of a camshaft-based wavemaker, we produce large amplitude shoaling waves in a stratified fluid in a laboratory tank. Simulations of solitary waves are used to guide the tuning of the wave generator to approximate solitary waves; thus nonlinear waves can be produced within the 4m long tank. PIV and synthetic schlieren measurements are made to study the transport of fluid by the wave as it moves up a sloping boundary. The results are then compared to numerical simulations and analyzed using finite time Lyapunov exponent calculations. This Lagrangian analysis provides an objective measure of barriers surrounding trapped regions in the flow. Supported by ONR MURI Grant N000141110701 (WHOI).
T-wave amplitude is related to physical fitness status.
Arbel, Yaron; Birati, Edo Y; Shapira, Itzhak; Topilsky, Yan; Wirguin, Michal; Canaani M D, Jonathan
2012-07-01
Abnormalities in repolarization may reflect underlying myocardial pathology and play a prominent role in arrhythmogenesis The T-wave amplitude has been associated with cardiovascular outcome in patients with acute myocardial infarction (MI) Additionally, T-wave amplitude is considered a predictor of arrhythmias, as well as being related to an individual's inflammatory status. The combined influence of different variables, such as inflammation, cardiovascular risk factors and physical fitness status, on the T-wave amplitude has not been evaluated to date. The aim of this study was to identify factors that affect the T-wave amplitude. Data from 255 consecutive apparently healthy individuals included in the Tel Aviv Medical Center Inflammation Survey (TAMCIS) were reviewed. All patients had undergone a physical examination and an exercise stress test, and different inflammatory and metabolic biomarkers (fibrinogen, potassium, and high-sensitivity C-reactive protein) were measured. Multivariate stepwise analysis revealed that the body mass index and the resting heart rate were significantly associated with the T-wave amplitude (β=-0.34, P physical fitness and not to his/her inflammatory status. ©2012, Wiley Periodicals, Inc.
Finite amplitude wave interaction with premixed laminar flames
Aslani, Mohamad; Regele, Jonathan D.
2014-11-01
The physics underlying combustion instability is an active area of research because of its detrimental impact in many combustion devices, such as turbines, jet engines, and liquid rocket engines. Pressure waves, ranging from acoustic waves to strong shocks, are potential sources of these disturbances. Literature on flame-disturbance interactions are primarily focused on either acoustics or strong shock wave interactions, with little information about the wide spectrum of behaviors that may exist between these two extremes. For example, the interaction between a flame and a finite amplitude compression wave is not well characterized. This phenomenon is difficult to study numerically due to the wide range of scales that need to be captured, requiring powerful and efficient numerical techniques. In this work, the interaction of a perturbed laminar premixed flame with a finite amplitude compression wave is investigated using the Parallel Adaptive Wavelet Collocation Method (PAWCM). This method optimally solves the fully compressible Navier-Stokes equations while capturing the essential scales. The results show that depending on the amplitude and duration of a finite amplitude disturbance, the interaction between these waves and premixed flames can produce a broad range of responses.
Stable Propagating Waves and Wake Fields in Relativistic Electromagnetic Plasma
DUAN Yi-Shi; XIE Bai-Song; TIAN Miao; YIN Xin-Tao; ZHANG Xin-Hui
2008-01-01
Stable propagating waves and wake fields in relativistic electromagnetic plasma are investigated. The incident electromagnetic field has a finite initial constant amplitude meanwhile the longitudinal momentum of electrons is taken into account in the problem. It is found that in the moving frame with transverse wave group velocity the stable propagating transverse electromagnetic waves and longitudinal plasma wake fields can exist in the appropriate regime of plasma.
Conjugate flows and amplitude bounds for internal solitary waves
N. I. Makarenko
2009-03-01
Full Text Available Amplitude bounds imposed by the conservation of mass, momentum and energy for strongly nonlinear waves in stratified fluid are considered. We discuss the theoretical scheme which allows to determine broadening limits for solitary waves in the terms of a given upstream density profile. Attention is focused on the continuously stratified flows having multiple broadening limits. The role of the mean density profile and the influence of fine-scale stratification are analyzed.
Amplitude-dependent contraction/elongation of nonlinear Lamb waves
Packo, Pawel; Staszewski, Wieslaw J.; Uhl, Tadeusz; Leamy, Michael J.
2016-04-01
Nonlinear elastic guided waves find application in various disciplines of science and engineering, such as non- destructive testing and structural health monitoring. Recent recognition and quantification of their amplitude- dependent changes in spectral properties has contributed to the development of new monitoring concepts for mechanical structures. The focus of this work is to investigate and predict amplitude-dependent shifts in Lamb wave dispersion curves. The theory for frequency/wavenumber shifts for plate waves, based on a Lindstedt-Poincaré perturbation approach, was presented by the authors in previous years. Equivalently, spectral properties changes can be seen as wavelength contraction/elongation. Within the proposed framework, the wavelength of a Lamb wave depends on several factors; e.g., wave amplitude and second-, third- and fourth-order elastic constants, and others. Various types of nonlinear effects are considered in presented studies. Sensitivity studies for model parameters, i.e. higher-order elastic constants, are performed to quantify their influence on Lamb wave frequency/wavenumber shifting, and to identify the key parameters governing wavelength tuning.
Lauben, D.; Cohen, M.; Inan, U.
2012-12-01
We deduce the 3d intra-plasmaspheric distribution of VLF wave power between conjugate regions of strong VLF wave amplitudes as measured by DEMETER for high-power terrestrial VLF transmitters during its ~6-yr lifetime. We employ a mixed WKB/full-wave technique to solve for the primary and secondary electromagnetic and electrostatic waves which are transmitted and reflected from strong cold-plasma density gradients and posited irregularities, in order to match the respective end-point measured amplitude distributions. Energy arriving in the conjugate region and also escaping to other regions of the magnetosphere is note. The resulting 3d distribution allows improved estimates for the long-term average particle scattering induced by terrestrial VLF transmitters.
MESSENGER Orbital Observations of Large-Amplitude Kelvin-Helmholtz Waves at Mercury's Magnetopause
Sundberg, Torbjorn; Boardsen, Scott A.; Slavin, James A.; Anderson, Brian J.; Korth, Haje; Zurbuchen, Thomas H.; Raines, Jim M.; Solomon, Sean C.
2012-01-01
We present a survey of Kelvi\\ n-Helmholtz (KH) waves at Mercury's magnetopause during MESSENGER's first Mercury year in orb it. The waves were identified on the basis of the well-established sawtooth wave signatures that are associated with non-linear KH vortices at the magnetopause. MESSENGER frequently observed such KH waves in the dayside region of the magnetosphere where the magnetosheath flow velocity is still sub -sonic, which implies that instability growth rates at Mercury's magnetopau are much larger than at Earth. We attribute these greater rates to the limited wave energy dissipation in Mercury's highly resistive regolith. The wave amplitude was often on the order of ' 00 nT or more, and the wave periods were - 10- 20 s. A clear dawn-dusk asymmetry is present in the data, in that all of the observed wave events occurred in the post-noon and dusk-side sectors of the magnetopause. This asymmetry is like ly related to finite Larmor-radius effects and is in agreement with results from particle-in-cell simulations of the instability. The waves were observed almost exclusively during periods when the north-south component of the magnetosheath magnetic field was northward, a pattern similar to that for most terrestrial KH wave events. Accompanying plasma measurements show that the waves were associated with the transport of magnetosheath plasma into the magnetosphere.
Large amplitude electromagnetic solitons in intense laser plasma interaction
Li Bai-Wen; Ishiguro S; Skoric M M
2006-01-01
This paper shows that the standing, backward- and forward-accelerated large amplitude relativistic electromagnetic solitons induced by intense laser pulse in long underdense collisionless homogeneous plasmas can be observed by particle simulations. In addition to the inhomogeneity of the plasma density, the acceleration of the solitons also depends upon not only the laser amplitude but also the plasma length. The electromagnetic frequency of the solitons is between about half and one of the unperturbed electron plasma frequency. The electrostatic field inside the soliton has a one-cycle structure in space, while the transverse electric and magnetic fields have half-cycle and one-cycle structure respectively.Analytical estimates for the existence of the solitons and their electromagnetic frequencies qualitatively coincide with our simulation results.
Arbitrary amplitude magnetosonic solitary and shock structures in spin quantum plasma
Sahu, Biswajit [Department of Mathematics, West Bengal State University, Barasat, Kolkata-700126 (India); Sinha, Anjana; Roychoudhury, Rajkumar; Khan, Manoranjan [Department of Instrumentation Science, Jadavpur University, Kolkata-700 032 (India)
2013-11-15
A nonlinear analysis is carried out for the arbitrary amplitude magnetosonic solitary and shock structures in spin quantum plasmas. A quantum magnetohydrodynamic model is used to describe the magnetosonic quantum plasma with the Bohm potential and the pressure like spin force for electrons. Analytical calculations are used to simplify the basic equations, which are then studied numerically. It is shown that the magnetic diffusivity is responsible for dissipation, which causes the shock-like structures rather than the soliton structures. Additionally, wave speed, Zeeman energy, and Bohm potential are found to have significant impact on the shock wave structures.
Large-amplitude ULF waves at high latitudes
Guido, T.; Tulegenov, B.; Streltsov, A. V.
2014-11-01
We present results from the statistical study of ULF waves detected by the fluxgate magnetometer in Gakona, Alaska during several experimental campaigns conducted at the High Frequency Active Auroral Research Program (HAARP) facility in years 2011-2013. We analyzed frequencies of ULF waves recorded during 26 strongly disturbed geomagnetic events (substorms) and compared them with frequencies of ULF waves detected during magnetically quiet times. Our analysis demonstrates that the frequency of the waves carrying most of the power in almost all these events is less than 1 mHz. We also analyzed data from the ACE satellite, measuring parameters of the solar wind in the L1 Lagrangian point between Earth and Sun, and found that in several occasions there is a strong correlation between oscillations of the magnetic field in the solar wind and oscillations detected on the ground. We also found several cases when there is no correlation between signals detected on ACE and on the ground. This finding suggests that these frequencies correspond to the fundamental eigenfrequency of the coupled magnetosphere-ionosphere system, and the amplitude of these waves can reach significant magnitude when the system is driven by the external driver (for example, the solar wind) with this particular frequency. When the frequency of the driver does not match the frequency of the system, the waves still are observed, but their amplitudes are much smaller.
Quasi-periodic behavior of ion acoustic solitary waves in electron-ion quantum plasma
Sahu, Biswajit [Department of Mathematics, West Bengal State University Barasat, Kolkata-700126 (India); Poria, Swarup [Department of Applied Mathematics, University of Calcutta Kolkata-700009 (India); Narayan Ghosh, Uday [Department of Mathematics, Siksha Bhavana, Visva Bharati University Santiniketan (India); Roychoudhury, Rajkumar [Physics and Applied Mathematics Unit, Indian Statistical Institute Kolkata-700108 (India)
2012-05-15
The ion acoustic solitary waves are investigated in an unmagnetized electron-ion quantum plasmas. The one dimensional quantum hydrodynamic model is used to study small as well as arbitrary amplitude ion acoustic waves in quantum plasmas. It is shown that ion temperature plays a critical role in the dynamics of quantum electron ion plasma, especially for arbitrary amplitude nonlinear waves. In the small amplitude region Korteweg-de Vries equation describes the solitonic nature of the waves. However, for arbitrary amplitude waves, in the fully nonlinear regime, the system exhibits possible existence of quasi-periodic behavior for small values of ion temperature.
On the Turbulence Beneath Finite Amplitude Water Waves
Babanin, Alexander V
2015-01-01
The paper by Beya et al. (2012, hereinafter BPB) has a general title of Turbulence Beneath Finite Amplitude Water Waves, but is solely dedicated to discussing the experiment by Babanin and Haus (2009, hereinafter BH) who conducted measurements of wave-induced non-breaking turbulence by particle image velocimetry (PIV). The authors of BPB conclude that their observations contradict those of BH. Here we argue that the outcomes of BPB do not contradict BH. In addition, although the main conclusion of BPB is that there is no turbulence observed in their experiment, it actually is observed.
Photoinduced Enhancement of the Charge Density Wave Amplitude
Singer, A.; Patel, S. K. K.; Kukreja, R.; Uhlíř, V.; Wingert, J.; Festersen, S.; Zhu, D.; Glownia, J. M.; Lemke, H. T.; Nelson, S.; Kozina, M.; Rossnagel, K.; Bauer, M.; Murphy, B. M.; Magnussen, O. M.; Fullerton, E. E.; Shpyrko, O. G.
2016-07-01
Symmetry breaking and the emergence of order is one of the most fascinating phenomena in condensed matter physics. It leads to a plethora of intriguing ground states found in antiferromagnets, Mott insulators, superconductors, and density-wave systems. Exploiting states of matter far from equilibrium can provide even more striking routes to symmetry-lowered, ordered states. Here, we demonstrate for the case of elemental chromium that moderate ultrafast photoexcitation can transiently enhance the charge-density-wave (CDW) amplitude by up to 30% above its equilibrium value, while strong excitations lead to an oscillating, large-amplitude CDW state that persists above the equilibrium transition temperature. Both effects result from dynamic electron-phonon interactions, providing an efficient mechanism to selectively transform a broad excitation of the electronic order into a well-defined, long-lived coherent lattice vibration. This mechanism may be exploited to transiently enhance order parameters in other systems with coupled degrees of freedom.
Amplitude or Higgs modes in d-wave superconductors
Barlas, Yafis; Varma, C. M.
2013-02-01
In Lorentz-invariant systems spontaneously broken gauge symmetry results in three types of fundamental excitations: density excitations, Higgs bosons (amplitude modes), and Goldstone bosons (phase modes). The density and phase modes are coupled by electromagnetic interactions while the amplitude modes are not. In s-wave superconductors, the Higgs mode, which can be observed only under special conditions, has been detected. We show that unconventional d-wave superconductors, such as the high-temperature cuprate superconductors, should have a rich assortment of Higgs bosons, each in a different irreducible representation of the point-group symmetry of the lattice. We also show that these modes have a characteristic singular spectral structure and discuss conditions for their observability.
Wave turbulence in magnetized plasmas
S. Galtier
2009-02-01
Full Text Available The paper reviews the recent progress on wave turbulence for magnetized plasmas (MHD, Hall MHD and electron MHD in the incompressible and compressible cases. The emphasis is made on homogeneous and anisotropic turbulence which usually provides the best theoretical framework to investigate space and laboratory plasmas. The solar wind and the coronal heating problems are presented as two examples of application of anisotropic wave turbulence. The most important results of wave turbulence are reported and discussed in the context of natural and simulated magnetized plasmas. Important issues and possible spurious interpretations are also discussed.
Nonlinear plasma wave in magnetized plasmas
Bulanov, Sergei V. [Kansai Photon Science Institute, JAEA, Kizugawa, Kyoto 619-0215 (Japan); Prokhorov Institute of General Physics, Russian Academy of Sciences, Moscow 119991 (Russian Federation); Moscow Institute of Physics and Technology, Dolgoprudny, Moscow region 141700 (Russian Federation); Esirkepov, Timur Zh.; Kando, Masaki; Koga, James K. [Kansai Photon Science Institute, JAEA, Kizugawa, Kyoto 619-0215 (Japan); Hosokai, Tomonao; Zhidkov, Alexei G. [Photon Pioneers Center, Osaka University, 2-8 Yamadaoka, Suita, Osaka 565-0871 (Japan); Japan Science and Technology Agency, CREST, 2-1, Yamadaoka, Suita, Osaka 565-0871 (Japan); Kodama, Ryosuke [Photon Pioneers Center, Osaka University, 2-8 Yamadaoka, Suita, Osaka 565-0871 (Japan); Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan)
2013-08-15
Nonlinear axisymmetric cylindrical plasma oscillations in magnetized collisionless plasmas are a model for the electron fluid collapse on the axis behind an ultrashort relativisically intense laser pulse exciting a plasma wake wave. We present an analytical description of the strongly nonlinear oscillations showing that the magnetic field prevents closing of the cavity formed behind the laser pulse. This effect is demonstrated with 3D PIC simulations of the laser-plasma interaction. An analysis of the betatron oscillations of fast electrons in the presence of the magnetic field reveals a characteristic “Four-Ray Star” pattern.
Testing THEMIS wave measurements against the cold plasma theory
Taubenschuss, Ulrich; Santolik, Ondrej; Le Contel, Olivier; Bonnell, John
2016-04-01
The THEMIS (Time History of Events and Macroscale Interactions during Substorms) mission records a multitude of electromagnetic waves inside Earth's magnetosphere and provides data in the form of high-resolution electric and magnetic waveforms. We use multi-component measurements of whistler mode waves and test them against the theory of wave propagation in a cold plasma. The measured ratio cB/E (c is speed of light in vacuum, B is magnetic wave amplitude, E is electric wave amplitude) is compared to the same quantity calculated from cold plasma theory over linearized Faraday's law. The aim of this study is to get estimates for measurement uncertainties, especially with regard to the electric field and the cold plasma density, as well as evaluating the validity of cold plasma theory inside Earth's radiation belts.
Ergun, R. E.; Holmes, J. C.; Goodrich, K. A.; Wilder, F. D.; Stawarz, J. E.; Eriksson, S.; Newman, D. L.; Schwartz, S. J.; Goldman, M. V.; Sturner, A. P.; Malaspina, D. M.; Usanova, M. E.; Torbert, R. B.; Argall, M.; Lindqvist, P.-A.; Khotyaintsev, Y.; Burch, J. L.; Strangeway, R. J.; Russell, C. T.; Pollock, C. J.; Giles, B. L.; Dorelli, J. J. C.; Avanov, L.; Hesse, M.; Chen, L. J.; Lavraud, B.; Le Contel, O.; Retino, A.; Phan, T. D.; Eastwood, J. P.; Oieroset, M.; Drake, J.; Shay, M. A.; Cassak, P. A.; Nakamura, R.; Zhou, M.; Ashour-Abdalla, M.; André, M.
2016-06-01
We report observations from the Magnetospheric Multiscale satellites of large-amplitude, parallel, electrostatic waves associated with magnetic reconnection at the Earth's magnetopause. The observed waves have parallel electric fields (E||) with amplitudes on the order of 100 mV/m and display nonlinear characteristics that suggest a possible net E||. These waves are observed within the ion diffusion region and adjacent to (within several electron skin depths) the electron diffusion region. They are in or near the magnetosphere side current layer. Simulation results support that the strong electrostatic linear and nonlinear wave activities appear to be driven by a two stream instability, which is a consequence of mixing cold (plasma in the magnetosphere with warm (~100 eV) plasma from the magnetosheath on a freshly reconnected magnetic field line. The frequent observation of these waves suggests that cold plasma is often present near the magnetopause.
Radial convection of finite ion temperature, high amplitude plasma blobs
Wiesenberger, M.; Madsen, Jens; Kendl, Alexander
2014-01-01
We present results from simulations of seeded blob convection in the scrape-off-layer of magnetically confined fusion plasmas. We consistently incorporate high fluctuation amplitude levels and finite Larmor radius (FLR) effects using a fully nonlinear global gyrofluid model. This is in line...... with conditions found in tokamak scrape-off-layers (SOL) regions. Varying the ion temperature, the initial blob width, and the initial amplitude, we found an FLR dominated regime where the blob behavior is significantly different from what is predicted by cold-ion models. The transition to this regime is very...
Finite-amplitude steady waves in plane viscous shear flows
Milinazzo, F. A.; Saffman, P. G.
1985-01-01
Computations of two-dimensional solutions of the Navier-Stokes equations are carried out for finite-amplitude waves on steady unidirectional flow. Several cases are considered. The numerical method employs pseudospectral techniques in the streamwise direction and finite differences on a stretched grid in the transverse direction, with matching to asymptotic solutions when unbounded. Earlier results for Poiseuille flow in a channel are re-obtained, except that attention is drawn to the dependence of the minimum Reynolds number on the physical constraint of constant flux or constant pressure gradient. Attempts to calculate waves in Couette flow by continuation in the velocity of a channel wall fail. The asymptotic suction boundary layer is shown to possess finite-amplitude waves at Reynolds numbers orders of magnitude less than the critical Reynolds number for linear instability. Waves in the Blasius boundary layer and unsteady Rayleigh profile are calculated by employing the artifice of adding a body force to cancel the spatial or temporal growth. The results are verified by comparison with perturbation analysis in the vicinity of the linear-instability critical Reynolds numbers.
The density stratification and amplitude dispersion of internal waves
Makarenko, N.; Ulanova, E.
2012-04-01
We consider the theoretical model of large amplitude internal solitary waves propagating in a weakly stratified fluid under gravity. It is well known that steady 2D Euler equations of non-homogeneous fluid reduce in this case to the second-order quasi-linear equation for a stream function (the Dubreil-Jacotin-Long equation). Subsequently, the shape of traveling solitary wave can be determined in the long-wave scaling limit by solving the dispersive KdV-type model equation. The non-linear terms of this equation depend considerably on the instantaneous fine-scale density profile formed over background linear- or exponential stratification (Benney&Ko, 1978; Borisov&Derzho 1990; Derzho&Grimshaw 1997; Makarenko, 1999; Makarenko, Maltseva and Kazakov, 2009). Now we derive and analyze Fredholm-type integral equations coupling immediately the fluid density coefficient with the dispersion function for internal solitary waves. The inverse problem which means to find the fine-scale density by known curve of the amplitude dispersion is discussed in more details.
Relativistic electromagnetic waves in an electron-ion plasma
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.
Waves and instabilities in plasmas
Chen Liu
1987-01-01
The topics covered in these notes are selective and tend to emphasize more on kinetic-theory approaches to waves and instabilities in both uniform and non-uniform plasmas, students are assumed to have some basic knowledge of plasma dynamics in terms of single-particle and fluid descriptions.
Measuring finite-frequency body-wave amplitudes and traveltimes
Sigloch, Karin; Nolet, Guust
2006-10-01
We have developed a method to measure finite-frequency amplitude and traveltime anomalies of teleseismic P waves. We use a matched filtering approach that models the first 25 s of a seismogram after the P arrival, which includes the depth phases pP and sP. Given a set of broad-band seismograms from a teleseismic event, we compute synthetic Green's functions using published moment tensor solutions. We jointly deconvolve global or regional sets of seismograms with their Green's functions to obtain the broad-band source time function. The matched filter of a seismogram is the convolution of the Green's function with the source time function. Traveltimes are computed by cross-correlating each seismogram with its matched filter. Amplitude anomalies are defined as the multiplicative factors that minimize the RMS misfit between matched filters and data. The procedure is implemented in an iterative fashion, which allows for joint inversion for the source time function, amplitudes, and a correction to the moment tensor. Cluster analysis is used to identify azimuthally distinct groups of seismograms when source effects with azimuthal dependence are prominent. We then invert for one source time function per group. We implement this inversion for a range of source depths to determine the most likely depth, as indicated by the overall RMS misfit, and by the non-negativity and compactness of the source time function. Finite-frequency measurements are obtained by filtering broad-band data and matched filters through a bank of passband filters. The method is validated on a set of 15 events of magnitude 5.8 to 6.9. Our focus is on the densely instrumented Western US. Quasi-duplet events (`quplets') are used to estimate measurement uncertainty on real data. Robust results are achieved for wave periods between 24 and 2 s. Traveltime dispersion is on the order of 0.5 s. Amplitude anomalies are on the order of 1 db in the lowest bands and 3 db in the highest bands, corresponding to
Simulation of laser-driven plasma beat-wave propagation in collisional weakly relativistic plasmas
Kaur, Maninder; Nandan Gupta, Devki
2016-11-01
The process of interaction of lasers beating in a plasma has been explored by virtue of particle-in-cell (PIC) simulations in the presence of electron-ion collisions. A plasma beat wave is resonantly excited by ponderomotive force by two relatively long laser pulses of different frequencies. The amplitude of the plasma wave become maximum, when the difference in the frequencies is equal to the plasma frequency. We propose to demonstrate the energy transfer between the laser beat wave and the plasma wave in the presence of electron-ion collision in nearly relativistic regime with 2D-PIC simulations. The relativistic effect and electron-ion collision both affect the energy transfer between the interacting waves. The finding of simulation results shows that there is a considerable decay in the plasma wave and the field energy over time in the presence of electron-ion collisions.
Electrostatic solitary waves in dusty pair-ion plasmas
Misra, A. P. [Department of Mathematics, Siksha Bhavana, Visva-Bharati University, Santiniketan-731 235, West Bengal (India); Adhikary, N. C. [Physical Sciences Division, Institute of Advanced Study in Science and Technology, Vigyan Path, Paschim Boragaon, Garchuk, Guwahati-781035, Assam (India)
2013-10-15
The propagation of electrostatic waves in an unmagnetized collisionless pair-ion plasma with immobile positively charged dusts is studied for both large- and small-amplitude perturbations. Using a two-fluid model for pair-ions, it is shown that there appear two linear ion modes, namely the “fast” and “slow” waves in dusty pair-ion plasmas. The properties of these wave modes are studied with different mass (m) and temperature (T) ratios of negative to positive ions, as well as the effects of immobile charged dusts (δ). For large-amplitude waves, the pseudopotential approach is performed, whereas the standard reductive perturbation technique is used to study the small-amplitude Korteweg-de Vries (KdV) solitons. The profiles of the pseudopotential, the large amplitude solitons as well as the dynamical evolution of KdV solitons, are numerically studied with the system parameters as above. It is found that the pair-ion plasmas with positively charged dusts support the propagation of solitary waves (SWs) with only the negative potential. The results may be useful for the excitation of SWs in laboratory dusty pair-ion plasmas, electron-free industrial plasmas as well as for observation in space plasmas where electron density is negligibly small compared to that of negative ions.
Modulated envelope localized wavepackets associated with electrostatic plasma waves
Kourakis, I; Kourakis, Ioannis; Shukla, Padma Kant
2004-01-01
The nonlinear amplitude modulation of known electrostatic plasma modes is examined in a generic manner, by applying a collisionless fluid model. Both cold (zero-temperature) and warm fluid descriptions are discussed and the results are compared. The moderately nonlinear oscillation regime is investigated by applying a multiple scale technique. The calculation leads to a Nonlinear Schrodinger-type Equation (NLSE), which describes the evolution of the slowly varying wave amplitude in time and space. The NLSE admits localized envelope (solitary wave) solutions of bright- (pulses) or dark- (holes, voids) type, whose characteristics (maximum amplitude, width) depend on intrinsic plasma parameters. Effects like amplitude perturbation obliqueness, finite temperature and defect (dust) concetration are explicitly considered. The relevance with similar highly localized modulated wave structures observed during recent satellite missions is discussed.
Electron Acoustic Waves in Pure Ion Plasmas
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.
Matda, Y.; Crawford, F. W.
1974-01-01
An economical low noise plasma simulation model is applied to a series of problems associated with electrostatic wave propagation in a one-dimensional, collisionless, Maxwellian plasma, in the absence of magnetic field. The model is described and tested, first in the absence of an applied signal, and then with a small amplitude perturbation, to establish the low noise features and to verify the theoretical linear dispersion relation at wave energy levels as low as 0.000,001 of the plasma thermal energy. The method is then used to study propagation of an essentially monochromatic plane wave. Results on amplitude oscillation and nonlinear frequency shift are compared with available theories. The additional phenomena of sideband instability and satellite growth, stimulated by large amplitude wave propagation and the resulting particle trapping, are described.
Zettergren, M. D.; Snively, J. B.; Komjathy, A.; Verkhoglyadova, O. P.
2017-02-01
Numerical models of ionospheric coupling with the neutral atmosphere are used to investigate perturbations of plasma density, vertically integrated total electron content (TEC), neutral velocity, and neutral temperature associated with large-amplitude acoustic waves generated by the initial ocean surface displacements from strong undersea earthquakes. A simplified source model for the 2011 Tohoku earthquake is constructed from estimates of initial ocean surface responses to approximate the vertical motions over realistic spatial and temporal scales. Resulting TEC perturbations from modeling case studies appear consistent with observational data, reproducing pronounced TEC depletions which are shown to be a consequence of the impacts of nonlinear, dissipating acoustic waves. Thermospheric acoustic compressional velocities are ˜±250-300 m/s, superposed with downward flows of similar amplitudes, and temperature perturbations are ˜300 K, while the dominant wave periodicity in the thermosphere is ˜3-4 min. Results capture acoustic wave processes including reflection, onset of resonance, and nonlinear steepening and dissipation—ultimately leading to the formation of ionospheric TEC depletions "holes"—that are consistent with reported observations. Three additional simulations illustrate the dependence of atmospheric acoustic wave and subsequent ionospheric responses on the surface displacement amplitude, which is varied from the Tohoku case study by factors of 1/100, 1/10, and 2. Collectively, results suggest that TEC depletions may only accompany very-large amplitude thermospheric acoustic waves necessary to induce a nonlinear response, here with saturated compressional velocities ˜200-250 m/s generated by sea surface displacements exceeding ˜1 m occurring over a 3 min time period.
Nonlinear Plasma Wave in Magnetized Plasmas
Bulanov, Sergei V; Kando, Masaki; Koga, James K; Hosokai, Tomonao; Zhidkov, Alexei G; Kodama, Ryosuke
2013-01-01
Nonlinear axisymmetric cylindrical plasma oscillations in magnetized collisionless plasmas are a model for the electron fluid collapse on the axis behind an ultrashort relativisically intense laser pulse exciting a plasma wake wave. We present an analytical description of the strongly nonlinear oscillations showing that the magnetic field prevents closing of the cavity formed behind the laser pulse. This effect is demonstrated with 3D PIC simulations of the laser-plasma interaction. An analysis of the betatron oscillations of fast electrons in the presence of the magnetic field reveals a characteristic "Four-Ray Star" pattern which has been observed in the image of the electron bunch in experiments [T. Hosokai, et al., Phys. Rev. Lett. 97, 075004 (2006)].
Esfandyari-Kalejahi, Abdolrasoul; Saberian, Ehsan; 10.1585/pfr.5.045
2011-01-01
Arbitrary amplitude ion-acoustic solitary waves (IASWs) are studied using Sagdeev-Potential approach in electron-positron-ion plasma with ultra-relativistic or non-relativistic degenerate electrons and positrons and the matching criteria of existence of such solitary waves are numerically investigated. It has been shown that the relativistic degeneracy of electrons and positrons has significant effects on the amplitude and the Mach-number range of IASWs. Also it is remarked that only compressive IASWs can propagate in both non-relativistic and ultra-relativistic degenerate plasmas.
On the Amplitude Equations for Weakly Nonlinear Surface Waves
Benzoni-Gavage, Sylvie; Coulombel, Jean-François
2012-09-01
Nonlocal generalizations of Burgers' equation were derived in earlier work by Hunter (Contemp Math, vol 100, pp 185-202. AMS, 1989), and more recently by Benzoni-Gavage and Rosini (Comput Math Appl 57(3-4):1463-1484, 2009), as weakly nonlinear amplitude equations for hyperbolic boundary value problems admitting linear surface waves. The local-in-time well-posedness of such equations in Sobolev spaces was proved by Benzoni-Gavage (Differ Integr Equ 22(3-4):303-320, 2009) under an appropriate stability condition originally pointed out by Hunter. The same stability condition has also been shown to be necessary for well-posedness in Sobolev spaces in a previous work of the authors in collaboration with Tzvetkov (Benzoni-Gavage et al. in Adv Math 227(6):2220-2240, 2011). In this article, we show how the verification of Hunter's stability condition follows from natural stability assumptions on the original hyperbolic boundary value problem, thus avoiding lengthy computations in each particular situation. We also show that the resulting amplitude equation has a Hamiltonian structure when the original boundary value problem has a variational origin. Our analysis encompasses previous equations derived for nonlinear Rayleigh waves in elasticity.
K. Sigsbee
2004-07-01
Full Text Available We present the statistics of Langmuir wave amplitudes in the Earth's foreshock using Cluster Wideband Data (WBD Plasma Wave Receiver electric field waveforms from spacecraft 2, 3 and 4 on 26 March 2002. The largest amplitude Langmuir waves were observed by Cluster near the boundary between the foreshock and solar wind, in agreement with earlier studies. The characteristics of the waves were similar for all three spacecraft, suggesting that variations in foreshock structure must occur on scales greater than the 50-100km spacecraft separations. The electric field amplitude probability distributions constructed using waveforms from the Cluster WBD Plasma Wave Receiver generally followed the log-normal statistics predicted by stochastic growth theory for the event studied. Comparison with WBD receiver data from 17 February 2002, when spacecraft 4 was set in a special manual gain mode, suggests non-optimal auto-ranging of the instrument may have had some influence on the statistics.
Nonlinear acoustic waves in a collisional self-gravitating dusty plasma
Guo Zhi-Rong; Yang Zeng-Qiang; Yin Bao-Xiang; Sun Mao-Zhu
2010-01-01
Using the reductive perturbation method,we investigate the small amplitude nonlinear acoustic wave in a collisional self-gravitating dusty plasma.The result shows that the small amplitude dust acoustic wave can be expressed by a modified Korteweg-de Vries equation,and the nonlinear wave is instable because of the collisions between the neutral gas molecules and the charged particles.
Large Amplitude Whistlers in the Magnetosphere Observed with Wind-Waves
Kellogg, P. J.; Cattell, C. A.; Goetz, K.; Monson, S. J.; Wilson, L. B., III
2011-01-01
We describe the results of a statistical survey of Wind-Waves data motivated by the recent STEREO/Waves discovery of large-amplitude whistlers in the inner magnetosphere. Although Wind was primarily intended to monitor the solar wind, the spacecraft spent 47 h inside 5 R(sub E) and 431 h inside 10 R(sub E) during the 8 years (1994-2002) that it orbited the Earth. Five episodes were found when whistlers had amplitudes comparable to those of Cattell et al. (2008), i.e., electric fields of 100 m V/m or greater. The whistlers usually occurred near the plasmapause. The observations are generally consistent with the whistlers observed by STEREO. In contrast with STEREO, Wind-Waves had a search coil, so magnetic measurements are available, enabling determination of the wave vector without a model. Eleven whistler events with useable magnetic measurements were found. The wave vectors of these are distributed around the magnetic field direction with angles from 4 to 48deg. Approximations to observed electron distribution functions show a Kennel-Petschek instability which, however, does not seem to produce the observed whistlers. One Wind episode was sampled at 120,000 samples/s, and these events showed a signature that is interpreted as trapping of electrons in the electrostatic potential of an oblique whistler. Similar waveforms are found in the STEREO data. In addition to the whistler waves, large amplitude, short duration solitary waves (up to 100 mV/m), presumed to be electron holes, occur in these passes, primarily on plasma sheet field lines mapping to the auroral zone.
Generation and Propagation of Finite-Amplitude Waves in Flexible Tubes (A)
Jensen, Leif Bjørnø
1972-01-01
Highly reproducible finite-amplitude waves, generated by a modified electromagnetic plane-wave generator, characterized by a rise time......Highly reproducible finite-amplitude waves, generated by a modified electromagnetic plane-wave generator, characterized by a rise time...
Residual Amplitude Modulation in Interferometric Gravitational Wave Detectors
Kokeyama, Keiko; Korth, William Z; Smith-Lefebvre, Nicolas; Arai, Koji; Adhikari, Rana X
2013-01-01
The effects of residual amplitude modulation (RAM) in laser interferometers using heterodyne sensing can be substantial and difficult to mitigate. In this work, we analyze the effects of RAM on a complex laser interferometer used for gravitational wave detection. The RAM introduces unwanted offsets in the cavity length signals and thereby shifts the operating point of the optical cavities from the nominal point via feedback control. This shift causes variations in the sensing matrix, and leads to degradation in the performance of the precision noise subtraction scheme of the multiple-degree-of-freedom control system. In addition, such detuned optical cavities produce an opto-mechanical spring, which also varies the sensing matrix. We use our simulations to derive requirements on RAM for the Advanced LIGO detectors, and show that the RAM expected in Advanced LIGO will not limit its sensitivity.
Residual amplitude modulation in interferometric gravitational wave detectors.
Kokeyama, Keiko; Izumi, Kiwamu; Korth, William Z; Smith-Lefebvre, Nicolas; Arai, Koji; Adhikari, Rana X
2014-01-01
The effects of residual amplitude modulation (RAM) in laser interferometers using heterodyne sensing can be substantial and difficult to mitigate. In this work, we analyze the effects of RAM on a complex laser interferometer used for gravitational wave detection. The RAM introduces unwanted offsets in the cavity length signals and thereby shifts the operating point of the optical cavities from the nominal point via feedback control. This shift causes variations in the sensing matrix, and leads to degradation in the performance of the precision noise subtraction scheme of the multiple-degree-of-freedom control system. In addition, such detuned optical cavities produce an optomechanical spring, which also perturbs the sensing matrix. We use our simulations to derive requirements on RAM for the Advanced LIGO (aLIGO) detectors, and show that the RAM expected in aLIGO will not limit its sensitivity.
Amplitude scaling for interchange motions of plasma filaments
Kube, R; Garcia, O E
2016-01-01
We numerically study the interchange motion of seeded plasma blobs in a reduced two-field fluid model. If we neglect the compression of the electric drift in the model, the maximal radial center-of-mass velocity V of the filament follows the familiar square-root scaling V ~ (\\Delta n/N)^1/2, where \\Delta n is the blob amplitude and N is the background density. When including compression of the electric drift to account for an inhomogeneous magnetic field, the numerical simulations reveal that the maximal blob velocity depends linearly on its initial amplitude, V ~ \\Delta n/N. When the relative initial amplitude of the filament exceeds approximately unity we recover the square root velocity scaling. We explain the observed scaling laws in t erms of the conserved energy integrals of the model equations. The compression term leads to a constraint on the maximum kinetic energy of the blob, which is not present if the drift compression is ignored. If the compression term is included, only approximately half of the...
Radial convection of finite ion temperature, high amplitude plasma blobs
Wiesenberger, M; Kendl, A
2014-01-01
We present results from simulations of seeded blob convection in the scrape-off-layer of magnetically confined fusion plasmas. We consistently incorporate high fluctuation amplitude levels and finite Larmor radius (FLR) effects using a fully nonlinear global gyrofluid model. This is in line with conditions found in tokamak scrape-off-layers (SOL) regions. Varying the ion temperature, the initial blob width and the initial amplitude, we found an FLR dominated regime where the blob behavior is significantly different from what is predicted by cold-ion models. The transition to this regime is very well described by the ratio of the ion gyroradius to the characteristic gradient scale length of the blob. We compare the global gyrofluid model with a partly linearized local model. For low ion temperatures we find that simulations of the global model show more coherent blobs with an increased cross-field transport compared to blobs simulated with the local model. The maximal blob amplitude is significantly higher in ...
Hyperbolic Mild Slope Equations with Inclusion of Amplitude Dispersion Effect: Random Waves
无
2008-01-01
New hyperbolic mild slope equations for random waves are developed with the inclusion of amplitude dispersion. The frequency perturbation around the peak frequency of random waves is adopted to extend the equations for regular waves to random waves. The nonlinear effect of amplitude dispersion is incorporated approximately into the model by only considering the nonlinear effect on the carrier waves of random waves, which is done by introducing a representative wave amplitude for the carrier waves. The computation time is greatly saved by the introduction of the representative wave amplitude. The extension of the present model to breaking waves is also considered in order to apply the new equations to surf zone. The model is validated for random waves propagate over a shoal and in surf zone against measurements.
Elastic reverse-time migration based on amplitude-preserving P- and S-wave separation
Yang, Jia-Jia; Luan, Xi-Wu; Fang, Gang; Liu, Xin-Xin; Pan, Jun; Wang, Xiao-Jie
2016-09-01
Imaging the PP- and PS-wave for the elastic vector wave reverse-time migration requires separating the P- and S-waves during the wave field extrapolation. The amplitude and phase of the P- and S-waves are distorted when divergence and curl operators are used to separate the P- and S-waves. We present a P- and S-wave amplitude-preserving separation algorithm for the elastic wavefield extrapolation. First, we add the P-wave pressure and P-wave vibration velocity equation to the conventional elastic wave equation to decompose the P- and S-wave vectors. Then, we synthesize the scalar P- and S-wave from the vector Pand S-wave to obtain the scalar P- and S-wave. The amplitude-preserved separated P- and S-waves are imaged based on the vector wave reverse-time migration (RTM). This method ensures that the amplitude and phase of the separated P- and S-wave remain unchanged compared with the divergence and curl operators. In addition, after decomposition, the P-wave pressure and vibration velocity can be used to suppress the interlayer reflection noise and to correct the S-wave polarity. This improves the image quality of P- and S-wave in multicomponent seismic data and the true-amplitude elastic reverse time migration used in prestack inversion.
Large Amplitude Solitary Waves in a Fluid－Filled Elastic Tube
DUANWen-Shah
2003-01-01
By usign the potential method to a fluid filled elastic tube, we obtained a solitary wave solution.Compared with recluetive perturbation method, this method can be used for larger amplitude solitary waves. The result is in agreement with that of small amplitude approximation from reduetive perturbation method when the amplitude is small enough.
Large Amplitude Solitary Waves in a Fluid-Filled Elastic Tube
DUAN Wen-Shan
2003-01-01
By using the potential method to a fluid filled elastic tube, we obtained a solitary wave solution. Comparedwith reductive perturbation method, this method can be used for larger amplitude solitary waves. The result is inagreement with that of small amplitude approximation from reductive perturbation method when the amplitude is smallenough.
Ion Acoustic Waves in the Presence of Electron Plasma Waves
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....
KINETIC THEORY OF PLASMA WAVES: Part II: Homogeneous Plasma
Westerhof, E.
2010-01-01
The theory of electromagnetic waves in a homogeneous plasma is reviewed. The linear response of the plasma to the waves is obtained in the form of the dielectric tensor. Waves ranging from the low frequency Alfven to the high frequency electron cyclotron waves are discussed in the limit of the cold
Kinetic theory of plasma waves: Part II homogeneous plasma
Westerhof, E.
2000-01-01
The theory of electromagnetic waves in a homogeneous plasma is reviewed. The linear response of the plasma to the waves is obtained in the form of the dielectric tensor. Waves ranging from the low frequency Alfven to the high frequency electron cyclotron waves are discussed in the limit of the cold
Kinetic theory of plasma waves - Part II: Homogeneous plasma
Westerhof, E.
2008-01-01
The theory of electromagnetic waves in a homogeneous plasma is reviewed. The linear response of the plasma to the waves is obtained in the form of the dielectric tensor. Waves ranging from the low frequency Alfven to the high frequency electron cyclotron waves axe discussed in the limit of the cold
Kinetic theory of plasma waves: Part II homogeneous plasma
Westerhof, E.
2000-01-01
The theory of electromagnetic waves in a homogeneous plasma is reviewed. The linear response of the plasma to the waves is obtained in the form of the dielectric tensor. Waves ranging from the low frequency Alfven to the high frequency electron cyclotron waves are discussed in the limit of the cold
KINETIC THEORY OF PLASMA WAVES: Part II: Homogeneous Plasma
Westerhof, E.
2010-01-01
The theory of electromagnetic waves in a homogeneous plasma is reviewed. The linear response of the plasma to the waves is obtained in the form of the dielectric tensor. Waves ranging from the low frequency Alfven to the high frequency electron cyclotron waves are discussed in the limit of the cold
Kinetic theory of plasma waves - Part II: Homogeneous plasma
Westerhof, E.
2008-01-01
The theory of electromagnetic waves in a homogeneous plasma is reviewed. The linear response of the plasma to the waves is obtained in the form of the dielectric tensor. Waves ranging from the low frequency Alfven to the high frequency electron cyclotron waves axe discussed in the limit of the cold
Electron waves and resonances in bounded plasmas
Vandenplas, Paul E
1968-01-01
General theoretical methods and experimental techniques ; the uniform plasma slab-condenser system ; the hollow cylindrical plasma ; scattering of a plane electromagnetic wave by a plasma column in steady magnetic fields (cold plasma approximation) ; hot non-uniform plasma column ; metallic and dielectric resonance probes, plasma-dielectric coated antenna, general considerations.
Faltýnek, J.; Hnilica, J.; Kudrle, V.
2017-01-01
Time resolved electron density in an atmospheric pressure amplitude modulated microwave plasma jet is determined using the microwave interferometry method, refined by numerical modelling of the propagation of non-planar electromagnetic waves in the vicinity of a small diameter, dense collisional plasma filament. The results are compared to those from the Stark broadening of the {{\\text{H}}β} emission line. Both techniques show, both qualitatively and quantitatively, a similar temporal evolution of electron density during one modulation period.
Oblique solitary waves in a five component plasma
Sijo, S.; Manesh, M.; Sreekala, G.; Venugopal, C., E-mail: cvgmgphys@yahoo.co.in [School of Pure and Applied Physics, Mahatma Gandhi University, Kottayam, 686 560 Kerala (India); Neethu, T. W. [Department of Physics, CMS College, Mahatma Gandhi University, Kottayam, 686 001 Kerala (India); Renuka, G. [Kerala State Council for Science, Technology and Environment, Thiruvananthapuram, 695 004 Kerala (India)
2015-12-15
We investigate the influence of a second electron component on oblique dust ion acoustic solitary waves in a five component plasma consisting of positively and negatively charged dust, hydrogen ions, and hotter and colder electrons. Of these, the heavier dust and colder photo-electrons are of cometary origin while the other two are of solar origin; electron components are described by kappa distributions. The K-dV equation is derived, and different attributes of the soliton such as amplitude and width are plotted for parameters relevant to comet Halley. We find that the second electron component has a profound influence on the solitary wave, decreasing both its amplitude and width. The normalized hydrogen density strongly influences the solitary wave by decreasing its width; the amplitude of the solitary wave, however, increases with increasing solar electron temperatures.
Hyperbolic Mild Slope Equations with Inclusion of Amplitude Dispersion Effect: Regular Waves
JIN Hong; ZOU Zhi-li
2008-01-01
A new form of hyperbolic mild slope equations is derived with the inclusion of the amplitude dispersion of nonlinear waves. The effects of including the amplitude dispersion effect on the wave propagation are discussed. Wave breaking mechanism is incorporated into the present model to apply the new equations to surf zone. The equations are solved numerically for regular wave propagation over a shoal and in surf zone, and a comparison is made against measurements. It is found that the inclusion of the amplitude dispersion can also improve model's performance on prediction of wave heights around breaking point for the wave motions in surf zone.
Electrostatic solitary waves in dusty pair-ion plasmas
Misra, A P
2013-01-01
The propagation of electrostatic waves in an unmagnetized collisionless pair-ion plasma with immobile positively charged dusts is studied for both large- and small-amplitude perturbations. Using a two-fluid model for pair-ions, it is shown that there appear two linear ion modes, namely the "fast" and "slow" waves in dusty pair-ion plasmas. The properties of these wave modes are studied with different mass $(m)$ and temperature $(T)$ ratios of negative to positive ions, as well as the effects of immobile charged dusts $(\\delta)$. For large-amplitude waves, the pseudopotential approach is performed, whereas the standard reductive perturbation technique (RPT) is used to study the small-amplitude Korteweg-de Vries (KdV) solitons. The profiles of the pseudopotential, the large amplitude solitons as well as the dynamical evolution of KdV solitons are numerically studied with the system parameters as above. It is found that the pair-ion plasmas with positively charged dusts support the propagation of solitary waves ...
On the Self-Focusing of Whistler Waves in a Radial Inhomogeneous Plasma
Balmashnov, A. A.
1980-01-01
The process of whistler wave self-focusing is experimentally investigated. It was found that a whistler wave propagating along the plasma column with a density crest excites a longitudinal wave of the same frequency propagating across the external magnetic field. The amplitude modulation...... of the latter wave is accompanied by a density modification, which leads to trapping of the whistler wave in a density trough in the center of the plasma column....
Oscillating two-stream instability of laser wakefield-driven plasma wave
Nafis Ahmad; V K Tripathi; Moiz Ahmad; M Rafat
2016-01-01
The laser wakefield-driven plasma wave in a low-density plasma is seen to be susceptible to the oscillating two-stream instability (OTSI). The plasma wave couples to two short wavelength plasma wave sidebands. The pump plasma wave and sidebands exert a ponderomotive force on the electrons driving a low-frequency quasimode. The electron density perturbation associated with this mode couples with the pump-driven electron oscillatory velocity to produce nonlinear currents driving the sidebands. At large pump amplitude, the instability grows faster than the ion plasma frequency and ions do not play a significant role. The growth rate of the quasimode, at large pump amplitude scales faster than linear. The growth rate is maximum for an optimum wave number of the quasimode and also increases with pump amplitude. Nonlocal effects, however reduce the growth rate by about half.
Body-wave traveltime and amplitude shifts from asymptotic travelling wave coupling
Pollitz, F.
2006-01-01
We explore the sensitivity of finite-frequency body-wave traveltimes and amplitudes to perturbations in 3-D seismic velocity structure relative to a spherically symmetric model. Using the approach of coupled travelling wave theory, we consider the effect of a structural perturbation on an isolated portion of the seismogram. By convolving the spectrum of the differential seismogram with the spectrum of a narrow window taper, and using a Taylor's series expansion for wavenumber as a function of frequency on a mode dispersion branch, we derive semi-analytic expressions for the sensitivity kernels. Far-field effects of wave interactions with the free surface or internal discontinuities are implicitly included, as are wave conversions upon scattering. The kernels may be computed rapidly for the purpose of structural inversions. We give examples of traveltime sensitivity kernels for regional wave propagation at 1 Hz. For the direct SV wave in a simple crustal velocity model, they are generally complicated because of interfering waves generated by interactions with the free surface and the Mohorovic??ic?? discontinuity. A large part of the interference effects may be eliminated by restricting the travelling wave basis set to those waves within a certain range of horizontal phase velocity. ?? Journal compilation ?? 2006 RAS.
Harmonics Effect on Ion-Bulk Waves in CH Plasmas
Feng, Q S; Liu, Z J; Cao, L H; Xiao, C Z; Wang, Q; He, X T
2016-01-01
The harmonics effect on ion-bulk (IBk) waves has been researched by Vlasov simulation. The condition of excitation of a large-amplitude IBk waves is given to explain the phenomenon of strong short-wavelength electrostatic activity in solar wind. When $k$ is much lower than $k_{lor}/2$ ($k_{lor}$ is the wave number at loss-of-resonance point), the IBk waves will not be excited to a large amplitude, because a large part of energy will be spread to harmonics. The nature of nonlinear IBk waves in the condition of $k
Saturation of Langmuir waves in laser-produced plasmas
Baker, K.L.
1996-04-01
This dissertation deals with the interaction of an intense laser with a plasma (a quasineutral collection of electrons and ions). During this interaction, the laser drives large-amplitude waves through a class of processes known as parametric instabilities. Several such instabilities drive one type of wave, the Langmuir wave, which involves oscillations of the electrons relative to the nearly-stationary ions. There are a number of mechanisms which limit the amplitude to which Langmuir waves grow. In this dissertation, these mechanisms are examined to identify qualitative features which might be observed in experiments and/or simulations. In addition, a number of experiments are proposed to specifically look for particular saturation mechanisms. In a plasma, a Langmuir wave can decay into an electromagnetic wave and an ion wave. This parametric instability is proposed as a source for electromagnetic emission near half of the incident laser frequency observed from laser-produced plasmas. This interpretation is shown to be consistent with existing experimental data and it is found that one of the previous mechanisms used to explain such emission is not. The scattering version of the electromagnetic decay instability is shown to provide an enhanced noise source of electromagnetic waves near the frequency of the incident laser.
Effect of attenuation correction on surface amplitude distribution of wind waves
Varkey, M.J.
Some selected wave profiles recorded using a ship borne wave recorder are analysed to study the effect of attenuation correction on the distribution of the surface amplitudes. A new spectral width parameter is defined to account for wide band...
Freak waves in negative-ion plasmas: an experiment revisited
Kourakis, Ioannis; Elkamash, Ibrahem; Reville, Brian
2016-10-01
Extreme events in the form of rogue waves (freak waves) occur widely in the open sea. These are space- and time-localised excitations, which appear unexpectedly and are characterised by a significant amplitude. Beyond ocean dynamics, the mechanisms underlying rogue wave formation are now being investigated in various physical contexts, including materials science, nonlinear optics and plasma physics, to mention but a few. We have undertaken an investigation, from first principles, of the occurrence of rogue waves associated with the propagation of electrostatic wavepackets in plasmas. Motivated by recent experimental considerations involving freak waves in negative-ion plasmas (NIP), we have addresed the occurrence of freak waves in NIP from first principles. An extended range of plasma parameter values was identified, where freak wave formation is possible, in terms of relevant plasma parameters. Our results extend -and partly contradict- the underlying assumptions in the interpretation of the aforementioned experiment, where a critical plasma configuration was considered and a Gardner equation approach was adopted. This work was supported from CPP/QUB funding. One of us (I. Elkamash) acknowledges financial support by an Egyptian Government fellowship.
Samiran Ghosh; Nikhil Chakrabarti; Manoranjan Khan; M R Gupta
2013-02-01
The conditions for the existence of low-frequency electrostatic drift wave in pair-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.
Space and Astrophysical Plasmas : Ionospheric plasma by VHF waves
R P Patel; Abhay Kumar Singh; R P Singh
2000-11-01
The amplitude scintillations of very high frequency electromagnetic wave transmitted from geo-stationary satellite at 244.168 MHz have been recorded at Varanasi (geom. lat. 14° 55'N) during 1991 to 1999. The data are analyzed to determine the statistical features of overhead ionospheric plasma irregularities which are mostly of small duration < 30 minutes and are predominant during pre-midnight period. The increase of solar activity generally increases the depth of scintillation. The auto-correlation functions and power spectra of scintillations predict that the scale length of these irregularities varies from 200–500 m having velocity of movement between 75 m/sec to 200 m/sec. These results agree well with the results obtained by other workers.
The Nonlinear Langmuir Waves in a Multi-ion-Component Plasma
CHEN Yin-Hua; LU Wei; WANG Wen-Hao
2001-01-01
We investigated the nonlinear Langmuir waves in a multi-ion-component low-temperature plasma. Beginning with the fluid theory of plasma, and taking fully nonlinear response of the low-frequency ion motion into account, we derived a set of equations governing the nonlinear coupling of the amplitude of the Langmuir wave and the Iow-frequency perturbation density. Using the Sagdeev potential method, we analyzed the characteristics of solitary wave. In the limit of small amplitude, the envelope soliton was found. Our investigation demonstrates that the properties of soliton in a multi-ion-component plasma are different from those of soliton in an electron-ion plasma.
Advanced Accelerators: Particle, Photon and Plasma Wave Interactions
Williams, Ronald L. [Florida A & M University, Tallahassee, FL (United States)
2017-06-29
The overall objective of this project was to study the acceleration of electrons to very high energies over very short distances based on trapping slowly moving electrons in the fast moving potential wells of large amplitude plasma waves, which have relativistic phase velocities. These relativistic plasma waves, or wakefields, are the basis of table-top accelerators that have been shown to accelerate electrons to the same high energies as kilometer-length linear particle colliders operating using traditional decades-old acceleration techniques. The accelerating electrostatic fields of the relativistic plasma wave accelerators can be as large as GigaVolts/meter, and our goal was to study techniques for remotely measuring these large fields by injecting low energy probe electron beams across the plasma wave and measuring the beam’s deflection. Our method of study was via computer simulations, and these results suggested that the deflection of the probe electron beam was directly proportional to the amplitude of the plasma wave. This is the basis of a proposed diagnostic technique, and numerous studies were performed to determine the effects of changing the electron beam, plasma wave and laser beam parameters. Further simulation studies included copropagating laser beams with the relativistic plasma waves. New interesting results came out of these studies including the prediction that very small scale electron beam bunching occurs, and an anomalous line focusing of the electron beam occurs under certain conditions. These studies were summarized in the dissertation of a graduate student who obtained the Ph.D. in physics. This past research program has motivated ideas for further research to corroborate these results using particle-in-cell simulation tools which will help design a test-of-concept experiment in our laboratory and a scaled up version for testing at a major wakefield accelerator facility.
The influence of storms on finite amplitude sand wave dynamics: an idealized nonlinear model
Campmans, G.H.P.; Roos, P.C.; de Vriend, H.J.; Hulscher, S.J.M.H.
2017-01-01
We investigate the effects of storms on finite amplitude sand wave growth using a new idealized nonlinear morphodynamic model. We find that the growth speed initially linearly increases with sand wave amplitude, after which nonlinear effects cause the growth to decrease. This finally leads to an
Numerical study of the propagation of small-amplitude atmospheric gravity wave
YUE Xianchang; YI Fan; LIU Yingjie; LI Fang
2005-01-01
By using a two-dimensional fully nonlinear compressible atmospheric dynamic numerical model, the propagation of a small amplitude gravity wave packet is simulated. A corresponding linear model is also developed for comparison. In an isothermal atmosphere, the simulations show that the nonlinear effects impacting on the propagation of a small amplitude gravity wave are negligible. In the nonisothermal atmosphere, however, the nonlinear effects are remarkable. They act to slow markedly down the propagation velocity of wave energy and therefore reduce the growth ratio of the wave amplitude with time. But the energy is still conserved. A proof of this is provided by the observations in the middle atmosphere.
Dichromatic Langmuir waves in degenerate quantum plasma
Dubinov, A. E.; Kitayev, I. N.
2015-06-01
Langmuir waves in fully degenerate quantum plasma are considered. It is shown that, in the linear approximation, Langmuir waves are always dichromatic. The low-frequency component of the waves corresponds to classical Langmuir waves, while the high-frequency component, to free-electron quantum oscillations. The nonlinear problem on the profile of dichromatic Langmuir waves is solved. Solutions in the form of a superposition of waves and in the form of beatings of its components are obtained.
Propagation of ion-acoustic solitary waves in a relativistic electron-positron-ion plasma
Saberian, E; Akbari-Moghanjoughi, M
2011-01-01
Propagation of large amplitude ion-acoustic solitary waves (IASWs) in a fully relativistic plasma consisting of cold ions and ultrarelativistic hot electrons and positrons is investigated using the Sagdeev's pseudopotential method in a relativistic hydrodynamics model. Effects of streaming speed of plasma fluid, thermal energy, positron density and positron temperature on large amplitude IASWs are studied by analysis of the pseudopotential structure. It is found that in regions that the streaming speed of plasma fluid is larger than that of solitary wave, by increasing the streaming speed of plasma fluid the depth and width of potential well increases and resulting in narrower solitons with larger amplitude. This behavior is opposite for the case where the streaming speed of plasma fluid is smaller than that of solitary wave. On the other hand, increase of the thermal energy results in wider solitons with smaller amplitude, because the depth and width of potential well decreases in that case. Additionally, th...
Evolution of Modulated Dispersive Electron Waves in a Plasma
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...... the wavepacket, (ii) the number of oscillations in the temporally observed packet is not identical with that in the spatially observed packet and (iii) continuously modulated waves exhibit recurrence of modulation. The experimental results agree with both a simple analysis based on the Schrodinger equation...
Tang, Xiangwei; Dombeck, John; Dai, Lei; Wilson, Lynn B; Breneman, Aaron; Hupach, Adam
2013-01-01
We present the first observations of large amplitude waves in a well-defined electron diffusion region at the sub-solar magnetopause using data from one THEMIS satellite. These waves identified as whistler mode waves, electrostatic solitary waves, lower hybrid waves and electrostatic electron cyclotron waves, are observed in the same 12-sec waveform capture and in association with signatures of active magnetic reconnection. The large amplitude waves in the electron diffusion region are coincident with abrupt increases in electron parallel temperature suggesting strong wave heating. The whistler mode waves which are at the electron scale and enable us to probe electron dynamics in the diffusion region were analyzed in detail. The energetic electrons (~30 keV) within the electron diffusion region have anisotropic distributions with T_{e\\perp}/T_{e\\parallel}>1 that may provide the free energy for the whistler mode waves. The energetic anisotropic electrons may be produced during the reconnection process. The whi...
Secondary Fast Magnetoacoustic Waves Trapped in Randomly Structured Plasmas
Yuan, Ding; Li, Bo; Walsh, Robert W.
2016-09-01
Fast magnetoacoustic waves are an important tool for inferring parameters of the solar atmosphere. We numerically simulate the propagation of fast wave pulses in randomly structured plasmas that mimic the highly inhomogeneous solar corona. A network of secondary waves is formed by a series of partial reflections and transmissions. These secondary waves exhibit quasi-periodicities in both time and space. Since the temporal and spatial periods are related simply through the speed of the fast wave, we quantify the properties of secondary waves by examining the dependence of the average temporal period (\\bar{p}) on the initial pulse width (w 0) and studying the density contrast ({δ }ρ ) and correlation length (L c ) that characterize the randomness of the equilibrium density profiles. For small-amplitude pulses, {δ }ρ does not alter \\bar{p} significantly. Large-amplitude pulses, on the other hand, enhance the density contrast when {δ }ρ is small but have a smoothing effect when {δ }ρ is sufficiently large. We found that \\bar{p} scales linearly with L c and that the scaling factor is larger for a narrower pulse. However, in terms of the absolute values of \\bar{p}, broader pulses generate secondary waves with longer periods, and this effect is stronger in random plasmas with shorter correlation lengths. Secondary waves carry the signatures of both the leading wave pulse and the background plasma. Our study may find applications in magnetohydrodynamic seismology by exploiting the secondary waves detected in the dimming regions after coronal mass ejections or extreme ultraviolet waves.
Low-Frequency Waves in Space Plasmas
Keiling, Andreas; Lee, Dong-Hun; Nakariakov, Valery
2016-02-01
Low-frequency waves in space plasmas have been studied for several decades, and our knowledge gain has been incremental with several paradigm-changing leaps forward. In our solar system, such waves occur in the ionospheres and magnetospheres of planets, and around our Moon. They occur in the solar wind, and more recently, they have been confirmed in the Sun's atmosphere as well. The goal of wave research is to understand their generation, their propagation, and their interaction with the surrounding plasma. Low-frequency Waves in Space Plasmas presents a concise and authoritative up-to-date look on where wave research stands: What have we learned in the last decade? What are unanswered questions? While in the past waves in different astrophysical plasmas have been largely treated in separate books, the unique feature of this monograph is that it covers waves in many plasma regions, including: Waves in geospace, including ionosphere and magnetosphere Waves in planetary magnetospheres Waves at the Moon Waves in the solar wind Waves in the solar atmosphere Because of the breadth of topics covered, this volume should appeal to a broad community of space scientists and students, and it should also be of interest to astronomers/astrophysicists who are studying space plasmas beyond our Solar System.
Nonlinear instability and chaos in plasma wave-wave interactions. II. Numerical methods and results
Kueny, C.S.; Morrison, P.J.
1995-05-01
In Part I of this work and Physics of Plasmas, June 1995, the behavior of linearly stable, integrable systems of waves in a simple plasma model was described using a Hamiltonian formulation. It was shown that explosive instability arises from nonlinear coupling between modes of positive and negative energy, with well-defined threshold amplitudes depending on the physical parameters. In this concluding paper, the nonintegrable case is treated numerically. Several sets of waves are considered, comprising systems of two and three degrees of freedom. The time evolution is modelled with an explicit symplectic integration algorithm derived using Lie algebraic methods. When initial wave amplitudes are large enough to support two-wave decay interactions, strongly chaotic motion destroys the separatrix bounding the stable region for explosive triplets. Phase space orbits then experience diffusive growth to amplitudes that are sufficient for explosive instability, thus effectively reducing the threshold amplitude. For initial amplitudes too small to drive decay instability, small perturbations might still grow to arbitrary size via Arnold diffusion. Numerical experiments do not show diffusion in this case, although the actual diffusion rate is probably underestimated due to the simplicity of the model.
Coroniti, F.V.; Greenstadt, E.W.; Moses, S.L. [TRW Space and Electronics Group, Redondo Beach, CA (United States); Tsurutani, B.T.; Smith, E.J. [California Institute of Technology, Pasadena, CA (United States)
1994-12-01
In early September, 1983 ISEE-3 made a long traversal of the distant dawnside magnetosheath starting near x = {minus}150 R{sub E} downstream. The distant magnetosheath often contains moderately intense plasma wave emissions at frequencies from several hundred Hz to 5 kHz. However, over time scales of many days, a clear correlation exists between the occurrence of the plasma waves and the cone angle ({theta}{sub xB}) between the magnetic field and the plasma flow velocity (x-direction). For {theta}{sub xB} large (small), the plasma wave amplitudes are near background (high). Sudden (<1 minute) changes in the local magnetic field orientation produce correspondingly sudden changes in the wave amplitudes. Statistically, the wave amplitudes decrease continuously with increasing {theta}{sub xB}. 7 refs., 5 figs.
Ion-acoustic cnoidal waves in a quantum plasma
Mahmood, Shahzad
2016-01-01
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.
Plasma Waves as a Benchmark Problem
Kilian, Patrick; Schreiner, Cedric; Spanier, Felix
2016-01-01
A large number of wave modes exist in a magnetized plasma. Their properties are determined by the interaction of particles and waves. In a simulation code, the correct treatment of field quantities and particle behavior is essential to correctly reproduce the wave properties. Consequently, plasma waves provide test problems that cover a large fraction of the simulation code. The large number of possible wave modes and the freedom to choose parameters make the selection of test problems time consuming and comparison between different codes difficult. This paper therefore aims to provide a selection of test problems, based on different wave modes and with well defined parameter values, that is accessible to a large number of simulation codes to allow for easy benchmarking and cross validation. Example results are provided for a number of plasma models. For all plasma models and wave modes that are used in the test problems, a mathematical description is provided to clarify notation and avoid possible misunderst...
Electromagnetic waves in a strong Schwarzschild plasma
Daniel, J.; Tajima, T.
1996-11-01
The physics of high frequency electromagnetic waves in a general relativistic plasma with the Schwarzschild metric is studied. Based on the 3 + 1 formalism, we conformalize Maxwell`s equations. The derived dispersion relations for waves in the plasma contain the lapse function in the plasma parameters such as in the plasma frequency and cyclotron frequency, but otherwise look {open_quotes}flat.{close_quotes} Because of this property this formulation is ideal for nonlinear self-consistent particle (PIC) simulation. Some of the physical consequences arising from the general relativistic lapse function as well as from the effects specific to the plasma background distribution (such as density and magnetic field) give rise to nonuniform wave equations and their associated phenomena, such as wave resonance, cutoff, and mode-conversion. These phenomena are expected to characterize the spectroscopy of radiation emitted by the plasma around the black hole. PIC simulation results of electron-positron plasma are also presented.
Wang, Ying; Guo, Yunxi
2017-09-01
In this paper, we developed, for the first time, the exact expressions of several periodic travelling wave solutions and a solitary wave solution for a shallow water wave model of moderate amplitude. Then, we present the existence theorem of the global weak solutions. Finally, we prove the stability of solution in L1(R) space for the Cauchy problem of the equation.
Wang, Ying; Guo, Yunxi
2016-07-01
In this paper, we developed, for the first time, the exact expressions of several periodic travelling wave solutions and a solitary wave solution for a shallow water wave model of moderate amplitude. Then, we present the existence theorem of the global weak solutions. Finally, we prove the stability of solution in L1(R) space for the Cauchy problem of the equation.
Verma, Prabal Singh; Sengupta, Sudip; Kaw, Predhiman
2012-07-01
A one-dimensional particle in cell simulation of large amplitude plasma oscillations is carried out to explore the physics beyond wave breaking in a cold homogeneous unmagnetized plasma. It is shown that after wave breaking, all energy of the plasma oscillation does not end up as random kinetic energy of particles, but some fraction, which is decided by Coffey's wave breaking limit in warm plasma, always remains with two oppositely propagating coherent Bernstein-Greene-Kruskal like modes with supporting trapped particle distributions. The randomized energy distribution of untrapped particles is found to be characteristically non-Maxwellian with a preponderance of energetic particles.
Farhad Kiyaei, Forough; Dorranian, Davoud
2017-01-01
Effects of the obliqueness and the strength of external magnetic field on the ion acoustic (IA) cnoidal wave in a nonextensive plasma are investigated. The reductive perturbation method is employed to derive the corresponding KdV equation for the IA wave. Sagdeev potential is extracted, and the condition of generation of IA waves in the form of cnoidal waves or solitons is discussed in detail. In this work, the domain of allowable values of nonextensivity parameter q for generation of the IA cnoidal wave in the plasma medium is considered. The results show that only the compressive IA wave may generate and propagate in the plasma medium. Increasing the strength of external magnetic field will increase the frequency of the wave and decrease its amplitude, while increasing the angle of propagation will decrease the frequency of the wave and increase its amplitude.
Fundamental plasma emission involving ion sound waves
Cairns, Iver H.
1987-01-01
The theory for fundamental plasma emission by the three-wave processes L + or - S to T (where L, S and T denote Langmuir, ion sound and transverse waves, respectively) is developed. Kinematic constraints on the characteristics and growth lengths of waves participating in the wave processes are identified. In addition the rates, path-integrated wave temperatures, and limits on the brightness temperature of the radiation are derived.
Relativistic warm plasma theory of nonlinear laser-driven electron plasma waves.
Schroeder, C B; Esarey, E
2010-05-01
A relativistic, warm fluid model of a nonequilibrium, collisionless plasma is developed and applied to examine nonlinear Langmuir waves excited by relativistically intense, short-pulse lasers. Closure of the covariant fluid theory is obtained via an asymptotic expansion assuming a nonrelativistic plasma temperature. The momentum spread is calculated in the presence of an intense laser field and shown to be intrinsically anisotropic. Coupling between the transverse and longitudinal momentum variances is enabled by the laser field. A generalized dispersion relation is derived for Langmuir waves in a thermal plasma in the presence of an intense laser field. Including thermal fluctuations in three-velocity-space dimensions, the properties of the nonlinear electron plasma wave, such as the plasma temperature evolution and nonlinear wavelength, are examined and the maximum amplitude of the nonlinear oscillation is derived. The presence of a relativistically intense laser pulse is shown to strongly influence the maximum plasma wave amplitude for nonrelativistic phase velocities owing to the coupling between the longitudinal and transverse momentum variances.
Dynamic Thomson Scattering from Nonlinear Electron Plasma Waves in a Raman Plasma Amplifier
Davies, A.; Katz, J.; Bucht, S.; Haberberger, D.; Bromage, J.; Zuegel, J. D.; Froula, D. H.; Trines, R.; Bingham, R.; Sadler, J.; Norreys, P. A.
2016-10-01
Electron plasma waves (EPW's) can be used to transfer significant energy from a long-pulse laser to a short-pulse seed laser through the Raman scattering instability. Successful implementation of Raman amplification could open an avenue to producing high-intensity pulses beyond the capabilities of current laser technology ( 1022 W / cm 2). This three-wave interaction takes advantage of the plasma's ability to sustain large-amplitude plasma waves. Having complete knowledge of the EPW amplitude is essential to establishing optimal parameters for high-efficiency Raman amplification. A dynamic Thomson-scattering diagnostic is being developed to spatially and temporally resolve the amplitude of the driven and thermal EPW's. By imaging the scattered probe light onto a novel pulse-front tilt compensated streaked optical spectrometer, the diffraction efficiency of this plasma wave can be measured as a function of space and time. These data will be used in conjunction with particle-in-cell simulations to determine the EPW's spatial and temporal profile. This will allow the effect of the EPW profile on Raman scattering to be experimentally determined. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.
Solitary Waves in Relativistic Electromagnetic Plasma
XIE Bai-Song; HUA Cun-Cai
2005-01-01
Solitary waves in relativistic electromagnetic plasmas are obtained numerically. The longitudinal momentum of electrons has been taken into account in the problem. It is found that in the moving frame with electromagnetic field propagating the solitary waves can exist in both cases, where the vector potential frequency is larger or smaller than the plasma characteristic frequency.
A Schamel equation for ion acoustic waves in superthermal plasmas
Williams, G., E-mail: gwilliams06@qub.ac.uk; Kourakis, I. [Centre for Plasma Physics, Department of Physics and Astronomy, Queen' s University Belfast, BT7 1NN, Northern Ireland (United Kingdom); Verheest, F. [Sterrenkundig Observatorium, Universiteit Gent, Krijgslaan 281, B-9000 Gent (Belgium); School of Chemistry and Physics, University of KwaZulu-Natal, Durban 4000 (South Africa); Hellberg, M. A. [School of Chemistry and Physics, University of KwaZulu-Natal, Durban 4000 (South Africa); Anowar, M. G. M. [Department of Physics, Begum Rokeya University, Rangpur, Rangpur-5400 (Bangladesh)
2014-09-15
An investigation of the propagation of ion acoustic waves in nonthermal plasmas in the presence of trapped electrons has been undertaken. This has been motivated by space and laboratory plasma observations of plasmas containing energetic particles, resulting in long-tailed distributions, in combination with trapped particles, whereby some of the plasma particles are confined to a finite region of phase space. An unmagnetized collisionless electron-ion plasma is considered, featuring a non-Maxwellian-trapped electron distribution, which is modelled by a kappa distribution function combined with a Schamel distribution. The effect of particle trapping has been considered, resulting in an expression for the electron density. Reductive perturbation theory has been used to construct a KdV-like Schamel equation, and examine its behaviour. The relevant configurational parameters in our study include the superthermality index κ and the characteristic trapping parameter β. A pulse-shaped family of solutions is proposed, also depending on the weak soliton speed increment u{sub 0}. The main modification due to an increase in particle trapping is an increase in the amplitude of solitary waves, yet leaving their spatial width practically unaffected. With enhanced superthermality, there is a decrease in both amplitude and width of solitary waves, for any given values of the trapping parameter and of the incremental soliton speed. Only positive polarity excitations were observed in our parametric investigation.
Dispersive analysis of the $S$-, $P$-, $D$-, and $F$-wave $\\pi\\pi$ amplitudes
Bydžovský, P; Nazari, V
2016-01-01
A reanalysis of $\\pi\\pi$ amplitudes for all important partial-waves below about 2 GeV is presented. A set of once subtracted dispersion relations with imposed crossing symmetry condition is used to modify unitary multi-channel amplitudes in the $S$, $P$, $D$, and $F$ waves. So far, these specific amplitudes constructed in our works and many other analyzes have been fitted only to experimental data and therefore do not fulfill the crossing symmetry condition. In the present analysis, the self consistent, i.e. unitary and fulfilling the crossing symmetry, amplitudes for the $S$, $P$, $D$, and $F$ waves are formed. The proposed very effective and simple method of modification of the $\\pi\\pi$ amplitudes does not change their previous-original mathematical structure and the method can be easily applied in various other analyzes.
Nonlinear Alfvén wave dynamics in plasmas
Sarkar, Anwesa; Chakrabarti, Nikhil [Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700 064 (India); Schamel, Hans [Theoretical Physics, University of Bayreuth, D-95440 Bayreuth (Germany)
2015-07-15
Nonlinear Alfvén wave dynamics is presented using Lagrangian fluid approach in a compressible collisional magnetized plasma. In the framework of two fluid dynamics, finite electron inertia is shown to serve as a dispersive effect acting against the convective nonlinearity. In a moving frame, the Alfvén wave can, therefore, form an arbitrarily strong amplitude solitary wave structure due to the balance between nonlinearity and dispersion. Weak amplitude Alfvén waves are shown to be governed by a modified KdV equation, which extends for finite dissipation to a mKdV-Burgers equation. These equations have well known solutions. Next, we have analyzed the fourth order nonlinear Alfvén wave system of equations both numerically and by approximation method. The results indicate a collapse of the density and magnetic field irrespective of the presence of dispersion. The wave magnetic field, however, appears to be less singular showing collapse only when the dispersive effects are negligible. These results may contribute to our understanding of the generation of strongly localized magnetic fields (and currents) in plasmas and are expected to be of special importance in the astrophysical context of magnetic star formation.
Nonlinear Alfvén wave dynamics in plasmas
Sarkar, Anwesa; Chakrabarti, Nikhil; Schamel, Hans
2015-07-01
Nonlinear Alfvén wave dynamics is presented using Lagrangian fluid approach in a compressible collisional magnetized plasma. In the framework of two fluid dynamics, finite electron inertia is shown to serve as a dispersive effect acting against the convective nonlinearity. In a moving frame, the Alfvén wave can, therefore, form an arbitrarily strong amplitude solitary wave structure due to the balance between nonlinearity and dispersion. Weak amplitude Alfvén waves are shown to be governed by a modified KdV equation, which extends for finite dissipation to a mKdV-Burgers equation. These equations have well known solutions. Next, we have analyzed the fourth order nonlinear Alfvén wave system of equations both numerically and by approximation method. The results indicate a collapse of the density and magnetic field irrespective of the presence of dispersion. The wave magnetic field, however, appears to be less singular showing collapse only when the dispersive effects are negligible. These results may contribute to our understanding of the generation of strongly localized magnetic fields (and currents) in plasmas and are expected to be of special importance in the astrophysical context of magnetic star formation.
Effects of Periodic Forcing Amplitude on the Spiral Wave Resonance Drift
WU Ning-Jie; LI Bing-Wei; YING He-Ping
2006-01-01
@@ We study dynamics of spiral waves under a uniform periodic temporal forcing in an excitable medium. With a specific combination of frequency and amplitude of the external periodic forcing, a resonance drift of a spiral wave occurs along a straight line, and it is accompanied by a complicated ‘flower-like’ motion on each side of this bifurcate boundary line. It is confirmed that the straight-line drift frequency of spiral waves is not locked to the nature rotation frequency as the forcing amplitude expends the range of the spiral wave frequency. These results are further verified numerically for a simplified kinematical model.
Alfven Wave Tomography for Cold MHD Plasmas
I.Y. Dodin; N.J. Fisch
2001-09-07
Alfven waves propagation in slightly nonuniform cold plasmas is studied by means of ideal magnetohydrodynamics (MHD) nonlinear equations. The evolution of the MHD spectrum is shown to be governed by a matrix linear differential equation with constant coefficients determined by the spectrum of quasi-static plasma density perturbations. The Alfven waves are shown not to affect the plasma density inhomogeneities, as they scatter off of them. The application of the MHD spectrum evolution equation to the inverse scattering problem allows tomographic measurements of the plasma density profile by scanning the plasma volume with Alfven radiation.
A penalization method for calculating the flow beneath travelling water waves of large amplitude
Constantin, Adrian; Scherzer, Otmar
2014-01-01
A penalization method for a suitable reformulation of the governing equations as a constrained optimization problem provides accurate numerical simulations for large-amplitude travelling water waves in irrotational flows and in flows with constant vorticity.
Revival of the Phase-Amplitude Description of a Quantum-Mechanical Wave Function
Rawitscher, George
2017-01-01
The phase-amplitude description of a wave function is formulated by means of a new linear differential-integral equation, which is valid in the region of turning points. A numerical example for a Coulomb potential is presented.
Modulational instability of ion-acoustic waves in a warm plasma
薛具奎; 段文山; 郎和
2002-01-01
Using the standard reductive perturbation technique, a nonlinear Schrodinger equation is derived to study themodulational instability of finite-amplitude ion-acoustic waves in a non-magnetized warm plasma. It is found thatthe inclusion of ion temperature in the equation modifies the nature of the ion-acoustic wave stability and the solitonstructures. The effects of ion plasma temperature on the modulational stability and ion-acoustic wave properties areinvestigated in detail.
Amplitude reconstruction from complete experiments and truncated partial-wave expansions
Workman, R L; Wunderlich, Y; Doering, M; Haberzettl, H
2016-01-01
We compare the methods of amplitude reconstruction, for a complete experiment and a truncated partial wave analysis, applied to the photoproduction of pseudo-scalar mesons. The approach is pedagogical, showing in detail how the amplitude reconstruction (observables measured at a single energy and angle) is related to a truncated partial-wave analysis (observables measured at a single energy and a number of angles).
Alvarez, R; Van Saarloos, W; Alvarez, Roberto; Hecke, Martin van; Saarloos, Wim van
1996-01-01
In many pattern forming systems that exhibit traveling waves, sources and sinks occur which separate patches of oppositely traveling waves. We show that simple qualitative features of their dynamics can be compared to predictions from coupled amplitude equations. In heated wire convection experiments, we find a discrepancy between the observed multiplicity of sources and theoretical predictions. The expression for the observed motion of sinks is incompatible with any amplitude equation description.
Saarloos, van, W.; Alvarez, R.; Hecke, van, M
1997-01-01
In many pattern forming systems that exhibit traveling waves, sources and sinks occur which separate patches of oppositely traveling waves. We show that simple qualitative features of their dynamics can be compared to predictions from coupled amplitude equations. In heated wire convection experiments, we find a discrepancy between the observed multiplicity of sources and theoretical predictions. The expression for the observed motion of sinks is incompatible with any amplitude equation descri...
Finite-amplitude waves in cylindrical lined ducts
Nayfeh, A. H.; Tsai, M.-S.
1974-01-01
A second-order uniformly valid expansion is obtained for nonlinear waves propagating in a cylindrical duct lined with a point-reacting acoustic material that consists of a porous sheet followed by honey-comb cavities and backed by the impervious walls of the duct. The effect of the liner is taken into account by coupling the waves in the duct with those in the liner. As in the two-dimensional case, the nonlinearity increases the attenuation rate at all frequencies except in narrow bandwidths around the resonant frequencies, irrespective of the geometrical dimensions of the liner or the acoustic properties of the porous sheet.
Parametric instabilities of large-amplitude parallel propagating Alfven waves: 2-D PIC simulation
Nariyuki, Yasuhiro; Hada, Tohru
2008-01-01
We discuss the parametric instabilities of large-amplitude parallel propagating Alfven waves using the 2-D PIC simulation code. First, we confirmed the results in the past study [Sakai et al, 2005] that the electrons are heated due to the modified two stream instability and that the ions are heated by the parallel propagating ion acoustic waves. However, although the past study argued that such parallel propagating longitudinal waves are excited by transverse modulation of parent Alfven wave, we consider these waves are more likely to be generated by the usual, parallel decay instability. Further, we performed other simulation runs with different polarization of the parent Alfven waves or the different ion thermal velocity. Numerical results suggest that the electron heating by the modified two stream instability due to the large amplitude Alfven waves is unimportant with most parameter sets.
Zhang, Heng; Duan, Wen-Shan; Qi, Xin; Yang, Lei
2016-02-12
Head-on collision and overtaking collision between a KdV solitary wave and an envelope solitary wave are first studied in present paper by using Particle-in-cell (PIC) method in a dusty plasma. There are phase shifts of the KdV solitary wave in both head-on collision and the overtaking collision, while no phase shift is found for the envelop solitary wave in any cases. The remarkable difference between head-on collision and the overtaking collision is that the phase shift of KdV solitary wave increases as amplitude of KdV solitary wave increases in head-on collision, while it decreases as amplitude of the KdV solitary wave increases in the overtaking collision. It is found that the maximum amplitude during the collision process is less than sum of two amplitudes of both solitary waves, but is larger than either of the amplitude.
Wave-driven Countercurrent Plasma Centrifuge
A.J. Fetterman and N.J. Fisch
2009-03-20
A method for driving rotation and a countercurrent flow in a fully ionized plasma centrifuge is described. The rotation is produced by radiofrequency waves near the cyclotron resonance. The wave energy is transferred into potential energy in a manner similar to the α channeling effect. The countercurrent flow may also be driven by radiofrequency waves. By driving both the rotation and the flow pattern using waves instead of electrodes, physical and engineering issues may be avoided.
Numerical Computation of Large Amplitude Internal Solitary Waves,
1981-03-20
provide adequate resolution. All computations were performed on a CDC Cyber 176 computer, and it takes slightly less than one CPU second to obtain a...H. Segur , Lgn Internal Waves in Fluids of Great Depth, Studies in Applied Math., 62 (1980), pp. 249-262. [3] E. Allgower and K. Georg, Simlicial -and
The Nonlinear Landau Damping Rate of a Driven Plasma Wave
Benisti, D; Strozzi, D J; Gremillet, L; Morice, O
2009-08-04
In this Letter, we discuss the concept of the nonlinear Landau damping rate, {nu}, of a driven electron plasma wave, and provide a very simple, practical, analytic formula for {nu} which agrees very well with results inferred from Vlasov simulations of stimulated Raman scattering. {nu} actually is more complicated an operator than a plain damping rate, and it may only be seen as such because it assumes almost constant values before abruptly dropping to 0. The decrease of {nu} to 0 is moreover shown to occur later when the wave amplitude varies in the direction transverse to its propagation.
An analytical model for the amplitude of lee waves forming on the boundary layer inversion
Sachsperger, Johannes; Serafin, Stefano; Stiperski, Ivana; Grubišić, Vanda
2016-04-01
Lee waves are horizontally propagating gravity waves with a typical wavelength of 5-15 km that may be generated when stratified flow is lifted over a mountain. A frequently observed type of such waves is that of interfacial lee waves. Those develop, similar to surface waves on a free water surface, when the upstream flow features a density discontinuity. Such conditions are often present for example at the capping inversion in boundary layer flow. The dynamics of interfacial lee waves can be described concisely with linear interfacial gravity wave theory. However, while this theoretical framework accurately describes the wavelength, it fails to properly predict the amplitude of lee waves. It is well known that large amplitude lee waves may lead to low-level turbulence, which poses a potential hazard for aviation. Therefore, this property of interfacial lee waves deserves further attention. In this study, we develop a simple analytical model for the amplitude of lee waves forming on the boundary layer inversion. This model is based on the energetics of two-layer flow. We obtain an expression for the wave amplitude by equating the energy loss across an internal jump with the energy radiation through lee waves. The verification of the result with water tank experiments of density-stratified two-layer flow over two-dimensional topography from the HYDRALAB campaign shows good agreement between theory and observations. This new analytical model may be useful in determining potential hazards of interfacial lee waves with negligible computational cost as compared to numerical weather prediction models.
Effect of wave localization on plasma instabilities
Levedahl, W.K.
1987-01-01
The Anderson model of wave localization in random media is invoked to study the effect of solar-wind density turbulence on plasma processes associated with the solar type-III radio burst. ISEE-3 satellite data indicate that a possible model for the type-III process is the parametric decay of Langmuir waves excited by solar-flare electron streams into daughter electromagnetic and ion-acoustic waves. The threshold for this instability, however, is much higher than observed Langmuir-wave levels because of rapid wave convection of the transverse electromagnetic daughter wave in the case where the solar wind is assumed homogeneous. Langmuir and transverse waves near critical density satisfy the Ioffe-Riegel criteria for wave localization in the solar wind with observed density fluctuations {approximately}1%. Computer simulations using a linearized hybrid code show that an electron beam will excite localized Langmuir waves in a plasma with density turbulence. An action-principle approach is used to develop a theory of nonlinear wave processes when waves are localized. A theory of resonant particles diffusion by localized waves is developed to explain the saturation of the beam-plasma instability.
Nonextensive dust acoustic waves in a charge varying dusty plasma
Bacha, Mustapha; Tribeche, Mouloud
2012-01-01
Our recent analysis on nonlinear nonextensive dust-acoustic waves (DA) [Amour and Tribeche in Phys. Plasmas 17:063702, 2010] is extended to include self-consistent nonadiabatic grain charge fluctuation. The appropriate nonextensive electron charging current is rederived based on the orbit-limited motion theory. Our results reveal that the amplitude, strength and nature of the nonlinear DA waves (solitons and shocks) are extremely sensitive to the degree of ion nonextensivity. Stronger is the electron correlation, more important is the charge variation induced nonlinear wave damping. The anomalous dissipation effects may prevail over that dispersion as the electrons evolve far away from their Maxwellian equilibrium. Our investigation may be of wide relevance to astronomers and space scientists working on interstellar dusty plasmas where nonthermal distributions are turning out to be a very common and characteristic feature.
Amplitude Distribution of Emission Wave for Cracking Process
Shahidan Shahiron
2016-01-01
Full Text Available Acoustic emission technique is a method of assessment for structural health monitoring system. This technique is an effective tool for the evaluation of any system without destroying the material conditions. It enables early crack detections and has very high sensitivity to crack growth. The crack patterns in concrete beam have been identified according to the type of cracking process and the crack classifications using the AE data parameters are mainly based on the AE amplitude, rise time, and average frequency. These data parameters have been analysed using statistical methods of b-value analysis. This research paper will mainly focus on the utilization of statistical b-value analysis in evaluating the emission amplitude distribution of concrete beams. The beam specimens (150 × 250 × 1900 mm were prepared in the laboratory system and tested with the four point bending test using cyclic loading together with acoustic emission monitoring system. The results showed that this statistical analysis is promising in determining the cracking process in concrete beams.
Finite amplitude waves in two-dimensional lined ducts
Nayfeh, A. H.; Tsai, M.-S.
1974-01-01
A second-order uniform expansion is obtained for nonlinear wave propagation in a two-dimensional duct lined with a point-reacting acoustic material consisting of a porous sheet followed by honeycomb cavities and backed by the impervious wall of the duct. The waves in the duct are coupled with those in the porous sheet and the cavities. An analytical expression is obtained for the absorption coefficient in terms of the sound frequency, the physical properties of the porous sheet, and the geometrical parameters of the flow configuration. The results show that the nonlinearity flattens and broadens the absorption vs. frequency curve, irrespective of the geometrical dimensions or the porous material acoustic properties, in agreement with experimental observations.
Evolution Of Nonlinear Waves in Compressing Plasma
P.F. Schmit, I.Y. Dodin, and N.J. Fisch
2011-05-27
Through particle-in-cell simulations, the evolution of nonlinear plasma waves is examined in one-dimensional collisionless plasma undergoing mechanical compression. Unlike linear waves, whose wavelength decreases proportionally to the system length L(t), nonlinear waves, such as solitary electron holes, conserve their characteristic size {Delta} during slow compression. This leads to a substantially stronger adiabatic amplification as well as rapid collisionless damping when L approaches {Delta}. On the other hand, cessation of compression halts the wave evolution, yielding a stable mode.
Kinetic Alfven wave turbulence in space plasmas
Sharma, R.P. [Plasma Simulation Laboratory, Centre for Energy Studies, Indian Institute of Technology, Delhi-110016, New Delhi (India); Kumar, Sachin, E-mail: dynamicalfven@gmail.co [Plasma Simulation Laboratory, Centre for Energy Studies, Indian Institute of Technology, Delhi-110016, New Delhi (India)
2010-07-26
This work presents the derivation of nonlinear coupled equations for the evolution of solar wind turbulence. These equations are governing the coupled dynamics of kinetic Alfven wave and ion acoustic wave. Numerical simulation of these equations is also presented. The ponderomotive nonlinearity is incorporated in the wave dynamics. Filamentation of kinetic Alfven wave and the turbulent spectra are presented in intermediate-{beta} plasmas at heliocentric distances (0.3 AU{<=}r<1.0 AU). The growing filaments and steeper turbulent spectra (of power law k{sup -S}, 5/3{<=}S{<=}3) can be responsible for plasma heating and particle acceleration in solar wind.
Nonlinear Electron Waves in Strongly Magnetized Plasmas
Pécseli, Hans; Juul Rasmussen, Jens
1980-01-01
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.......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...
Roll dynamics of a ship sailing in large amplitude head waves
Daalen, E.F.G.; Gunsing, M.; Grasman, J.; Remmert, J.
2014-01-01
Some ship types may show significant rolling when sailing in large-amplitude (near) head waves. The dynamics of the ship are such that the roll motion is affected by the elevation of the encountering waves. If the natural roll period (without forcing) is about half the period of the forcing by the w
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.
Tsai, Ya-Yi; Tsai, Jun-Yi; I, Lin
2016-06-01
Rogue waves--rare uncertainly emerging localized events with large amplitudes--have been experimentally observed in many nonlinear wave phenomena, such as water waves, optical waves, second sound in superfluid He II (ref. ) and ion acoustic waves in plasmas. Past studies have mainly focused on one-dimensional (1D) wave behaviour through modulation instabilities, and to a lesser extent on higher-dimensional behaviour. The question whether rogue waves also exist in nonlinear 3D acoustic-type plasma waves, the kinetic origin of their formation and their correlation with surrounding 3D waveforms are unexplored fundamental issues. Here we report the direct experimental observation of dust acoustic rogue waves in dusty plasmas and construct a picture of 3D particle focusing by the surrounding tilted and ruptured wave crests, associated with the higher probability of low-amplitude holes for rogue-wave generation.
Large-Amplitude Electrostatic Waves Observed at a Supercritical Interplanetary Shock
Wilson, L. B., III; Cattell, C. A.; Kellogg, P. J.; Goetz, K.; Kersten, K.; Kasper, J. C.; Szabo, A.; Wilber, M.
2010-01-01
We present the first observations at an interplanetary shock of large-amplitude (> 100 mV/m pk-pk) solitary waves and large-amplitude (approx.30 mV/m pk-pk) waves exhibiting characteristics consistent with electron Bernstein waves. The Bernstein-like waves show enhanced power at integer and half-integer harmonics of the cyclotron frequency with a broadened power spectrum at higher frequencies, consistent with the electron cyclotron drift instability. The Bernstein-like waves are obliquely polarized with respect to the magnetic field but parallel to the shock normal direction. Strong particle heating is observed in both the electrons and ions. The observed heating and waveforms are likely due to instabilities driven by the free energy provided by reflected ions at this supercritical interplanetary shock. These results offer new insights into collisionless shock dissipation and wave-particle interactions in the solar wind.
Amplitude wave in one-dimensional complex Ginzburg-Landau equation
Xie Ling-Ling; Gao Jia-Zhen; Xie Wei-Miao; Gao Ji-Hua
2011-01-01
The wave propagation in the one-dimensional complex Ginzburg-Landau equation (CGLE) is studied by considering a wave source at the system boundary.A special propagation region,which is an island-shaped zone surrounded by the defect turbulence in the system parameter space,is observed in our numerical experiment.The wave signal spreads in the whole space with a novel amplitude wave pattern in the area.The relevant factors of the pattern formation,such as the wave speed,the maximum propagating distance and the oscillatory frequency,are studied in detail.The stability and the generality of the region are testified by adopting various initial conditions.This finding of the amplitude pattern extends the wave propagation region in the parameter space and presents a new signal transmission mode,and is therefore expected to be of much importance.
Clayton, C. E.; Marsh, K. A.; Dyson, A.; Everett, M.; Lal, A.; Leemans, W. P.; Williams, R.; Joshi, C.
1993-01-01
High-gradient acceleration of externally injected 2.1-MeV electrons by a laser beat wave driven relativistic plasma wave has been demonstrated for the first time. Electrons with energies up to the detection limit of 9.1 MeV were detected when such a plasma wave was resonantly excited using a two-frequency laser. This implies a gradient of 0.7 GeV/m, corresponding to a plasma-wave amplitude of more than 8%. The electron signal was below detection threshold without injection or when the laser was operated on a single frequency.
Rufai, O. R., E-mail: rrufai@csir.co.za [Council for Scientific and Industrial Research, Pretoria (South Africa); Bharuthram, R., E-mail: rbharuthram@uwc.ac.za [University of the Western Cape, Bellville (South Africa); Singh, S. V., E-mail: satyavir@iigs.iigm.res.in; Lakhina, G. S., E-mail: lakhina@iigs.iigm.res.in [Indian Institute of Geomagnetism, New Panvel (W), Navi, Mumbai-410218 (India)
2015-10-15
The effect of excess superthermal electrons is investigated on finite amplitude nonlinear ion-acoustic waves in a magnetized auroral plasma. The plasma model consists of a cold ion fluid, Boltzmann distribution of cool electrons, and kappa distributed hot electron species. The model predicts the evolution of negative potential solitons and supersolitons at subsonic Mach numbers region, whereas, in the case of Cairn's nonthermal distribution model for the hot electron species studied earlier, they can exist both in the subsonic and supersonic Mach number regimes. For the dayside auroral parameters, the model generates the super-acoustic electric field amplitude, speed, width, and pulse duration of about 18 mV/m, 25.4 km/s, 663 m, and 26 ms, respectively, which is in the range of the Viking spacecraft measurements.
Quantum ion-acoustic solitary waves in weak relativistic plasma
Biswajit Sahu
2011-06-01
Small amplitude quantum ion-acoustic solitary waves are studied in an unmagnetized twospecies 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 perturbation method. A linear dispersion relation is also obtained taking into account the relativistic effect. The properties of quantum ion-acoustic solitary waves, obtained from the deformed KdV equation, are studied taking into account the quantum mechanical effects in the weak relativistic limit. It is found that relativistic effects signiﬁcantly modify the properties of quantum ion-acoustic waves. Also the effect of the quantum parameter on the nature of solitary wave solutions is studied in some detail.
Nonlinear Electrostatic Wave Equations for Magnetized Plasmas
Dysthe, K.B.; Mjølhus, E.; Pécseli, Hans
1984-01-01
The lowest order kinetic effects are included in the equations for nonlinear electrostatic electron waves in a magnetized plasma. The modifications of the authors' previous analysis based on a fluid model are discussed.......The lowest order kinetic effects are included in the equations for nonlinear electrostatic electron waves in a magnetized plasma. The modifications of the authors' previous analysis based on a fluid model are discussed....
Drift waves in a weakly ionized plasma
Popovic, M.; Melchior, H.
1968-01-01
A dispersion relation for low frequency drift waves in a weakly ionized plasma has been derived, and through numerical calculations the effect of collisions between the charged and the neutral particles is estimated.......A dispersion relation for low frequency drift waves in a weakly ionized plasma has been derived, and through numerical calculations the effect of collisions between the charged and the neutral particles is estimated....
Dumont, R
2004-07-01
This document gathers a series of transparencies presented in the framework of the week-long lectures 'hot plasmas 2004' and dedicated to the physics of wave-plasma interaction. The structure of this document is as follows: 1) wave and diverse plasmas, 2) basic equations (Maxwell equations), 3) waves in a fluid plasma, and 4) waves in a kinetic plasma (collisionless plasma)
Ionospheric electron acceleration by electromagnetic waves near regions of plasma resonances
Villalon, Elena
1989-03-01
Electron acceleration by electromagnetic fields propagating in the inhomogeneous ionospheric plasma is investigated. It is found that high-amplitude short wavelength electrostatic waves are generated by the incident electromagnetic fields that penetrate the radio window. These waves can very efficiently transfer their energy to the electrons if the incident frequency is near the second harmonic of the cyclotron frequency.
Secondary fast magnetoacoustic waves trapped in randomly structured plasmas
Yuan, Ding; Walsh, Robert W
2016-01-01
Fast magnetoacoustic wave is an important tool for inferring solar atmospheric parameters. We numerically simulate the propagation of fast wave pulses in randomly structured plasmas mimicking the highly inhomogeneous solar corona. A network of secondary waves is formed by a series of partial reflections and transmissions. These secondary waves exhibit quasi-periodicities in both time and space. Since the temporal and spatial periods are related simply through the fast wave speed, we quantify the properties of secondary waves by examining the dependence of the average temporal period ($\\bar{p}$) on the initial pulse width ($w_0$) as well as the density contrast ($\\delta_\\rho$) and correlation length ($L_c$) that characterize the randomness of the equilibrium density profiles. For small-amplitude pulses, $\\delta_\\rho$ does not alter $\\bar{p}$ significantly. Large-amplitude pulses, on the other hand, enhance the density contrast when $\\delta_\\rho$ is small but have a smoothing effect when $\\delta_\\rho$ is suffic...
Observation of an Alfv\\'en Wave Parametric Instability in a Laboratory Plasma
Dorfman, S
2016-01-01
A shear Alfv\\'en wave parametric instability is observed for the first time in the laboratory. When a single finite $\\omega/\\Omega_i$ kinetic Alfv\\'en wave (KAW) is launched in the Large Plasma Device above a threshold amplitude, three daughter modes are produced. These daughter modes have frequencies and parallel wave numbers that are consistent with copropagating KAW sidebands and a low frequency nonresonant mode. The observed process is parametric in nature, with the frequency of the daughter modes varying as a function of pump wave amplitude. The daughter modes are spatially localized on a gradient of the pump wave magnetic field amplitude in the plane perpendicular to the background field, suggesting that perpendicular nonlinear forces (and therefore $k_{\\perp}$ of the pump wave) play an important role in the instability process. Despite this, modulational instability theory with $k_{\\perp}=0$ has several features in common with the observed nonresonant mode and Alfv\\'en wave sidebands.
Behavior of gravity waves with limited amplitude in the vicinity of critical layer
无
2002-01-01
By using the FICE scheme, a numerical simulation of three-dimensional nonlinear propagation of gravity wave packet in a wind-stratified atmosphere is presented. The whole nonlinear propagation process of the gravity wave packet is shown; the propagation behavior of gravity waves in the vicinity of critical layer is analyzed. The results show that gravity waves encounter the critical layer when propagating in the fair winds whose velocities increase with height, and the height of critical layer propagating nonlinearly is lower than that expected by the linear gravity waves theory; the amplitudes of gravity waves increase with height as a whole before gravity waves encounter the critical layer, but the increasing extent is smaller than the result given by the linear theory of gravity waves, while the amplitudes of gravity waves reduce when gravity waves meet the critical layer; the energy of wave decreases with height, especially at the critical layer; the vertical wavelength reduces with the height increasing, but it does not become zero.
Frequency dispersion of small-amplitude capillary waves in viscous fluids
Denner, Fabian
2016-01-01
This work presents a detailed study of the dispersion of capillary waves with small amplitude in viscous fluids using an analytically derived solution to the initial value problem of a small-amplitude capillary wave as well as direct numerical simulation. A rational parametrization for the dispersion of capillary waves in the underdamped regime is proposed, including predictions for the wavenumber of critical damping based on a harmonic oscillator model. The scaling resulting from this parametrization leads to a self-similar solution of the frequency dispersion of capillary waves that covers the entire underdamped regime, which allows an accurate evaluation of the frequency at a given wavenumber, irrespective of the fluid properties. This similarity also reveals characteristic features of capillary waves, for instance that critical damping occurs when the characteristic timescales of dispersive and dissipative mechanisms are balanced. In addition, the presented results suggest that the widely adopted hydrodyn...
Weakly nonlinear electron plasma waves in collisional plasmas
Pecseli, H. L.; Rasmussen, J. Juul; Tagare, S. G.
1986-01-01
The nonlinear evolution of a high frequency plasma wave in a weakly magnetized, collisional plasma is considered. In addition to the ponderomotive-force-nonlinearity the nonlinearity due to the heating of the electrons is taken into account. A set of nonlinear equations including the effect...... of a constantly maintained pump wave is derived and a general dispersion relation describing the modulation of the high frequency wave due to different low frequency responses is obtained. Particular attention is devoted to a purely growing modulation. The relative importance of the ponderomotive force...
Increasing signal amplitude in fiber Bragg grating detection of Lamb waves using remote bonding.
Wee, Junghyun; Wells, Brian; Hackney, Drew; Bradford, Philip; Peters, Kara
2016-07-20
Networks of fiber Bragg grating (FBG) sensors can serve as structural health monitoring systems for large-scale structures based on the collection of ultrasonic waves. The demodulation of structural Lamb waves using FBG sensors requires a high signal-to-noise ratio because the Lamb waves are of low amplitudes. This paper compares the signal transfer amplitudes between two adhesive mounting configurations for an FBG to detect Lamb waves propagating in an aluminum plate: a directly bonded FBG and a remotely bonded FBG. In the directly bonded FBG case, the Lamb waves create in-plane and out-of-plane displacements, which are transferred through the adhesive bond and detected by the FBG sensor. In the remotely bonded FBG case, the Lamb waves are converted into longitudinal and flexural traveling waves in the optical fiber at the adhesive bond, which propagate through the optical fiber and are detected by the FBG sensor. A theoretical prediction of overall signal attenuation also is performed, which is the combination of material attenuation in the plate and optical fiber and attenuation due to wave spreading in the plate. The experimental results demonstrate that remote bonding of the FBG significantly increases the signal amplitude measured by the FBG.
Generalized Langmuir Waves in Magnetized Kinetic Plasmas
Willes, A. J.; Cairns, Iver H.
2000-01-01
The properties of unmagnetized Langmuir waves and cold plasma magnetoionic waves (x, o, z and whistler) are well known. However, the connections between these modes in a magnetized kinetic plasma have not been explored in detail. Here, wave properties are investigated by numerically solving the dispersion equation derived from the Vlasov equations both with and without a beam instability present. For omega(sub p)>Omega(sub e), it is shown that the generalized Langmuir mode at oblique propagation angles has magnetic z-mode characteristics at low wave numbers and thermal Langmuir mode characteristics at high wave numbers. For omega(sub p)Langmuir mode instead connects to the whistler mode at low wave numbers. The transition from the Langmuir/z mode to the Langmuir/whistler mode near omega(sub p) = Omega(sub e) is rapid. In addition, the effects on wave dispersion and polarization after adding a beam are investigated. Applications of this theory to magnetized Langmuir waves in Earth's foreshock and the solar wind, to waves observed near the plasma frequency in the auroral regions, and to solar type III bursts are discussed.
Sekihara, Takayasu
2016-01-01
For a general two-body bound state in quantum mechanics, both in the stable and decaying cases, we establish a way to extract its two-body wave function in momentum space from the scattering amplitude of the constituent two particles. For this purpose, we first show that the two-body wave function of the bound state corresponds to the residue of the off-shell scattering amplitude at the bound state pole. Then, we examine our scheme to extract the two-body wave function from the scattering amplitude in several schematic models. As a result, the two-body wave functions from the Lippmann--Schwinger equation coincides with that from the Schr\\"{o}dinger equation for an energy-independent interaction. Of special interest is that the two-body wave function from the scattering amplitude is automatically scaled; the norm of the two-body wave function, to which we refer as the compositeness, is unity for an energy-independent interaction, while the compositeness deviates from unity for an energy-dependent interaction, ...
Exact solution to the Coulomb wave using the linearized phase-amplitude method
Shuji Kiyokawa
2015-08-01
Full Text Available The author shows that the amplitude equation from the phase-amplitude method of calculating continuum wave functions can be linearized into a 3rd-order differential equation. Using this linearized equation, in the case of the Coulomb potential, the author also shows that the amplitude function has an analytically exact solution represented by means of an irregular confluent hypergeometric function. Furthermore, it is shown that the exact solution for the Coulomb potential reproduces the wave function for free space expressed by the spherical Bessel function. The amplitude equation for the large component of the Dirac spinor is also shown to be the linearized 3rd-order differential equation.
Dispersion relations with crossing symmetry for pipi D and F wave amplitudes
Kaminski, R
2011-01-01
A set of once subtracted dispersion relations with imposed crossing symmetry condition for the pipi D- and F-wave amplitudes is derived and analyzed. An example of numerical calculations in the effective two pion mass range from the threshold to 1.1 GeV is presented. It is shown that these new dispersion relations impose quite strong constraints on the analyzed pipi interactions and are very useful tools to test the pipi amplitudes. One of the goals of this work is to provide a complete set of equations required for easy use. Full analytical expressions are presented. Along with the well known dispersion relations successful in testing the pipi S- and P-wave amplitudes, those presented here for the D and F waves give a complete set of tools for analyzes of the pipi interactions.
Kannajosyula, H.; Lissenden, C. J.; Rose, J. L.
2013-01-01
We present a method for mode selection of guided wave modes and beam steering using purely amplitude variation across a one dimensional linear array of transducers. The method is distinct from apodization of phased array transducers that involves amplitude variation in addition to time delays and merely aims to improve the spectral characteristics of the transducer. The relationship between amplitude variation and the pitch of the array is derived by considering the resulting transduction as analogous to a spatio-temporal filter approach. It is also shown analytically and through numerical examples that the proposed method results in bidirectional guided waves when the steering angle is zero. Further, for non-zero steering angles, the waves travel in four directions, including the desired direction. Experimental studies are suggested.
Nonlinear effects of the finite amplitude ultrasound wave in biological tissues
无
2000-01-01
Nonlinear effects will occur during the transmission of the finite amplitude wave in biological tissues.The theoretical prediction and experimental demonstration of the nonlinear effects on the propagation of the finite amplitude wave at the range of biomedical ultrasound frequency and intensity are studied.Results show that the efficiency factor and effective propagation distance will decrease while the attenuation coefficient increases due to the existence of nonlinear effects.The experimental results coincided quite well with the theory.This shows that the effective propagation distance and efficiency factor can be used to describe quantitatively the influence of nonlinear effects on the propagation of the finite amplitude sound wave in biological tissues.
Twisted electron-acoustic waves in plasmas
Aman-ur-Rehman, Ali, S.; Khan, S. A.; Shahzad, K.
2016-08-01
In the paraxial limit, a twisted electron-acoustic (EA) wave is studied in a collisionless unmagnetized plasma, whose constituents are the dynamical cold electrons and Boltzmannian hot electrons in the background of static positive ions. The analytical and numerical solutions of the plasma kinetic equation suggest that EA waves with finite amount of orbital angular momentum exhibit a twist in its behavior. The twisted wave particle resonance is also taken into consideration that has been appeared through the effective wave number qeff accounting for Laguerre-Gaussian mode profiles attributed to helical phase structures. Consequently, the dispersion relation and the damping rate of the EA waves are significantly modified with the twisted parameter η, and for η → ∞, the results coincide with the straight propagating plane EA waves. Numerically, new features of twisted EA waves are identified by considering various regimes of wavelength and the results might be useful for transport and trapping of plasma particles in a two-electron component plasma.
Experimental study of nonlinear dust acoustic solitary waves in a dusty plasma
Bandyopadhyay, P; Sen, A; Kaw, P K
2008-01-01
The excitation and propagation of finite amplitude low frequency solitary waves are investigated in an Argon plasma impregnated with kaolin dust particles. A nonlinear longitudinal dust acoustic solitary wave is excited by pulse modulating the discharge voltage with a negative potential. It is found that the velocity of the solitary wave increases and the width decreases with the increase of the modulating voltage, but the product of the solitary wave amplitude and the square of the width remains nearly constant. The experimental findings are compared with analytic soliton solutions of a model Kortweg-de Vries equation.
The supergravity fields for a D-brane with a travelling wave from string amplitudes
Black, William; Turton, David
2010-01-01
We calculate the supergravity fields sourced by a D-brane with a null travelling wave from disk amplitudes in type IIB string theory compactified on T^4 x S^1. The amplitudes reproduce the non-trivial features of the previously known two-charge supergravity solutions in the D-brane/momentum frame, providing a direct link between the microscopic bound states and their macroscopic descriptions.
The supergravity fields for a D-brane with a travelling wave from string amplitudes
Black, William, E-mail: w.black@qmul.ac.u [Queen Mary University of London, Centre for Research in String Theory, Department of Physics, Mile End Road, London E1 4NS (United Kingdom); Russo, Rodolfo, E-mail: r.russo@qmul.ac.u [Queen Mary University of London, Centre for Research in String Theory, Department of Physics, Mile End Road, London E1 4NS (United Kingdom); Turton, David, E-mail: d.j.turton@qmul.ac.u [Queen Mary University of London, Centre for Research in String Theory, Department of Physics, Mile End Road, London E1 4NS (United Kingdom)
2010-11-08
We calculate the supergravity fields sourced by a D-brane with a null travelling wave from disk amplitudes in type IIB string theory compactified on T{sup 4}xS{sup 1}. The amplitudes reproduce all the non-trivial features of the previously known two-charge supergravity solutions in the D-brane/momentum duality frame, providing a direct link between the microscopic bound states and their macroscopic descriptions.
On the rogue waves propagation in non-Maxwellian complex space plasmas
El-Tantawy, S. A.; El-Awady, E. I.; Tribeche, M.
2015-11-01
The implications of the non-Maxwellian electron distributions (nonthermal/or suprathermal/or nonextensive distributions) are examined on the dust-ion acoustic (DIA) rogue/freak waves in a dusty warm plasma. Using a reductive perturbation technique, the basic set of fluid equations is reduced to a nonlinear Schrödinger equation. The latter is used to study the nonlinear evolution of modulationally unstable DIA wavepackets and to describe the rogue waves (RWs) propagation. Rogue waves are large-amplitude short-lived wave groups, routinely observed in space plasmas. The possible region for the rogue waves to exist is defined precisely for typical parameters of space plasmas. It is shown that the RWs strengthen for decreasing plasma nonthermality and increasing superthermality. For nonextensive electrons, the RWs amplitude exhibits a bit more complex behavior, depending on the entropic index q. Moreover, our numerical results reveal that the RWs exist with all values of the ion-to-electron temperature ratio σ for nonthermal and superthermal distributions and there is no limitation for the freak waves to propagate in both two distributions in the present plasma system. But, for nonextensive electron distribution, the bright- and dark-type waves can propagate in this case, which means that there is a limitation for the existence of freak waves. Our systematic investigation should be useful in understanding the properties of DIA solitary waves that may occur in non-Maxwellian space plasmas.
On the rogue waves propagation in non-Maxwellian complex space plasmas
El-Tantawy, S. A., E-mail: samireltantawy@yahoo.com; El-Awady, E. I., E-mail: eielawady@hotmail.com [Department of Physics, Faculty of Science, Port Said University, Port Said 42521 (Egypt); Tribeche, M., E-mail: mouloudtribeche@yahoo.fr, E-mail: mtribeche@usthb.dz [Plasma Physics Group, Theoretical Physics Laboratory, Faculty of Physics, University of Bab-Ezzouar, USTHB, BP 32, El Alia, Algiers 16111 (Algeria)
2015-11-15
The implications of the non-Maxwellian electron distributions (nonthermal/or suprathermal/or nonextensive distributions) are examined on the dust-ion acoustic (DIA) rogue/freak waves in a dusty warm plasma. Using a reductive perturbation technique, the basic set of fluid equations is reduced to a nonlinear Schrödinger equation. The latter is used to study the nonlinear evolution of modulationally unstable DIA wavepackets and to describe the rogue waves (RWs) propagation. Rogue waves are large-amplitude short-lived wave groups, routinely observed in space plasmas. The possible region for the rogue waves to exist is defined precisely for typical parameters of space plasmas. It is shown that the RWs strengthen for decreasing plasma nonthermality and increasing superthermality. For nonextensive electrons, the RWs amplitude exhibits a bit more complex behavior, depending on the entropic index q. Moreover, our numerical results reveal that the RWs exist with all values of the ion-to-electron temperature ratio σ for nonthermal and superthermal distributions and there is no limitation for the freak waves to propagate in both two distributions in the present plasma system. But, for nonextensive electron distribution, the bright- and dark-type waves can propagate in this case, which means that there is a limitation for the existence of freak waves. Our systematic investigation should be useful in understanding the properties of DIA solitary waves that may occur in non-Maxwellian space plasmas.
Material measurement method based on femtosecond laser plasma shock wave
Zhong, Dong; Li, Zhongming
2017-03-01
The acoustic emission signal of laser plasma shock wave, which comes into being when femtosecond laser ablates pure Cu, Fe, and Al target material, has been detected by using the fiber Fabry-Perot (F-P) acoustic emission sensing probe. The spectrum characters of the acoustic emission signals for three kinds of materials have been analyzed and studied by using Fourier transform. The results show that the frequencies of the acoustic emission signals detected from the three kinds of materials are different. Meanwhile, the frequencies are almost identical for the same materials under different ablation energies and detection ranges. Certainly, the amplitudes of the spectral character of the three materials show a fixed pattern. The experimental results and methods suggest a potential application of the plasma shock wave on-line measurement based on the femtosecond laser ablating target by using the fiber F-P acoustic emission sensor probe.
Han, Wenchen; Cheng, Hongyan; Dai, Qionglin; Li, Haihong; Ju, Ping; Yang, Junzhong
2016-10-01
In this work, we investigate the dynamics in a ring of identical Stuart-Landau oscillators with conjugate coupling systematically. We analyze the stability of the amplitude death and find the stability independent of the number of oscillators. When the amplitude death state is unstable, a large number of states such as homogeneous oscillation death, heterogeneous oscillation death, homogeneous oscillation, and wave propagations are found and they may coexist. We also find that all of these states are related to the unstable spatial modes to the amplitude death state.
Autism spectrum disorders and the amplitude of auditory brainstem response wave I.
Santos, Mariline; Marques, Cristina; Nóbrega Pinto, Ana; Fernandes, Raquel; Coutinho, Miguel Bebiano; Almeida E Sousa, Cecília
2017-04-01
To determine whether children with autism spectrum disorders (ASDs) have an increased number of wave I abnormal amplitudes in auditory brainstem responses (ABRs) than age- and sex-matched typically developing children. This analytical case-control study compared patients with ASDs between the ages of 2 and 6 years and children who had a language delay not associated with any other pathology. Amplitudes of ABR waves I and V; absolute latencies (ALs) of waves I, III, and V; and interpeak latencies (IPLs) I-III, III-IV, and I-V at 90 dB were compared between ASD patients and normally developing children. The study enrolled 40 children with documented ASDs and 40 age- and sex-matched control subjects. Analyses of the ABR showed that children with ASDs exhibited higher amplitudes of wave 1 than wave V (35%) more frequently than the control group (10%), and this difference between groups reached statistical significance by Chi-squared analysis. There were no significant differences in ALs and IPLs between ASD children and matched controls. To the best of our knowledge, this is the first case-control study testing the amplitudes of ABR wave I in ASD children. The reported results suggest a potential for the use of ABR recordings in children, not only for the clinical assessment of hearing status, but also for the possibility of using amplitude of ABR wave I as an early marker of ASDs allowing earlier diagnosis and intervention. Autism Res 2017. © 2017 International Society for Autism Research, Wiley Periodicals, Inc.
Unusually low-amplitude anisotropic wave-train events of cosmic ray intensity during 1981-1994
Rajesh K Mishra; Rekha Agarwal Mishra
2005-02-01
Investigation has been made for unusually low-amplitude anisotropic wave train events (LAE) for cosmic ray intensity data of Deep River neutron monitoring station during the period 1981-94. It has been observed that the phase of diurnal anisotropy remains in the same co-rotational direction for most of the LAEs while the phase shifts to early hours for some of the LAEs in diurnal anisotropy. During minimum solar activity, LAEs have been observed to be dominant. Solar wind plasma (SWP) parameters, interplanetary magnetic field and various features at solar disk have also been studied. The amplitude remains low continuously for most of the days while the phase shifts to earlier hours. Occurrence of LAE is independent of the nature of interplanetary magnetic field (IMF).
Nonlinear electromagnetic waves in a degenerate electron-positron plasma
El-Labany, S.K., E-mail: skellabany@hotmail.com [Department of Physics, Faculty of Science, Damietta University, New Damietta (Egypt); El-Taibany, W.F., E-mail: eltaibany@hotmail.com [Department of Physics, College of Science for Girls in Abha, King Khalid University, Abha (Saudi Arabia); El-Samahy, A.E.; Hafez, A.M.; Atteya, A., E-mail: ahmedsamahy@yahoo.com, E-mail: am.hafez@sci.alex.edu.eg, E-mail: ahmed_ateya2002@yahoo.com [Department of Physics, Faculty of Science, Alexandria University, Alexandria (Egypt)
2015-08-15
Using the reductive perturbation technique (RPT), the nonlinear propagation of magnetosonic solitary waves in an ultracold, degenerate (extremely dense) electron-positron (EP) plasma (containing ultracold, degenerate electron, and positron fluids) is investigated. The set of basic equations is reduced to a Korteweg-de Vries (KdV) equation for the lowest-order perturbed magnetic field and to a KdV type equation for the higher-order perturbed magnetic field. The solutions of these evolution equations are obtained. For better accuracy and searching on new features, the new solutions are analyzed numerically based on compact objects (white dwarf) parameters. It is found that including the higher-order corrections results as a reduction (increment) of the fast (slow) electromagnetic wave amplitude but the wave width is increased in both cases. The ranges where the RPT can describe adequately the total magnetic field including different conditions are discussed. (author)
Nonlinear Electromagnetic Waves in a Degenerate Electron-Positron Plasma
El-Labany, S. K.; El-Taibany, W. F.; El-Samahy, A. E.; Hafez, A. M.; Atteya, A.
2015-08-01
Using the reductive perturbation technique (RPT), the nonlinear propagation of magnetosonic solitary waves in an ultracold, degenerate (extremely dense) electron-positron (EP) plasma (containing ultracold, degenerate electron, and positron fluids) is investigated. The set of basic equations is reduced to a Korteweg-de Vries (KdV) equation for the lowest-order perturbed magnetic field and to a KdV type equation for the higher-order perturbed magnetic field. The solutions of these evolution equations are obtained. For better accuracy and searching on new features, the new solutions are analyzed numerically based on compact objects (white dwarf) parameters. It is found that including the higher-order corrections results as a reduction (increment) of the fast (slow) electromagnetic wave amplitude but the wave width is increased in both cases. The ranges where the RPT can describe adequately the total magnetic field including different conditions are discussed.
Nonlinear damping of a finite amplitude whistler wave due to modified two stream instability
Saito, Shinji, E-mail: saito@stelab.nagoya-u.ac.jp [Graduate School of Science, Nagoya University, Nagoya (Japan); Solar-Terrestrial Environment Laboratory, Nagoya University, Nagoya (Japan); Nariyuki, Yasuhiro, E-mail: nariyuki@edu.u-toyama.ac.jp [Faculty of Human Development, University of Toyama, Toyama (Japan); Umeda, Takayuki, E-mail: umeda@stelab.nagoya-u.ac.jp [Solar-Terrestrial Environment Laboratory, Nagoya University, Nagoya (Japan)
2015-07-15
A two-dimensional, fully kinetic, particle-in-cell simulation is used to investigate the nonlinear development of a parallel propagating finite amplitude whistler wave (parent wave) with a wavelength longer than an ion inertial length. The cross field current of the parent wave generates short-scale whistler waves propagating highly oblique directions to the ambient magnetic field through the modified two-stream instability (MTSI) which scatters electrons and ions parallel and perpendicular to the magnetic field, respectively. The parent wave is largely damped during a time comparable to the wave period. The MTSI-driven damping process is proposed as a cause of nonlinear dissipation of kinetic turbulence in the solar wind.
River plumes as a source of large-amplitude internal waves in the coastal ocean
Nash, Jonathan D.; Moum, James N.
2005-09-01
Satellite images have long revealed the surface expression of large amplitude internal waves that propagate along density interfaces beneath the sea surface. Internal waves are typically the most energetic high-frequency events in the coastal ocean, displacing water parcels by up to 100m and generating strong currents and turbulence that mix nutrients into near-surface waters for biological utilization. While internal waves are known to be generated by tidal currents over ocean-bottom topography, they have also been observed frequently in the absence of any apparent tide-topography interactions. Here we present repeated measurements of velocity, density and acoustic backscatter across the Columbia River plume front. These show how internal waves can be generated from a river plume that flows as a gravity current into the coastal ocean. We find that the convergence of horizontal velocities at the plume front causes frontal growth and subsequent displacement downward of near-surface waters. Individual freely propagating waves are released from the river plume front when the front's propagation speed decreases below the wave speed in the water ahead of it. This mechanism generates internal waves of similar amplitude and steepness as internal waves from tide-topography interactions observed elsewhere, and is therefore important to the understanding of coastal ocean mixing.
Does the schock wave in a highly ionized non-isothermal plasma really exist ?
Rukhadze, A A; Samkharadze, T
2015-01-01
Here we study the structure of a highly ionizing shock wave in a gas of high atmospheric pressure. We take into account the gas ionization when the gas temperature reaches few orders of an ionization potential. It is shown that after gasdynamic temperature-raising shock and formation of a highly-ionized nonisothermal plasma $T_e>>T_i$ only the solitary ion-sound wave (soliton) can propagate in this plasma. In such a wave the charge separation occurs: electrons and ions form the double electric layer with the electric field. The shock wave form, its amplitude and front width are obtained.
Facilitation of epileptic activity during sleep is mediated by high amplitude slow waves.
Frauscher, Birgit; von Ellenrieder, Nicolás; Ferrari-Marinho, Taissa; Avoli, Massimo; Dubeau, François; Gotman, Jean
2015-06-01
Epileptic discharges in focal epilepsy are frequently activated during non-rapid eye movement sleep. Sleep slow waves are present during this stage and have been shown to include a deactivated ('down', hyperpolarized) and an activated state ('up', depolarized). The 'up' state enhances physiological rhythms, and we hypothesize that sleep slow waves and particularly the 'up' state are the specific components of non-rapid eye movement sleep that mediate the activation of epileptic activity. We investigated eight patients with pharmaco-resistant focal epilepsies who underwent combined scalp-intracerebral electroencephalography for diagnostic evaluation. We analysed 259 frontal electroencephalographic channels, and manually marked 442 epileptic spikes and 8487 high frequency oscillations during high amplitude widespread slow waves, and during matched control segments with low amplitude widespread slow waves, non-widespread slow waves or no slow waves selected during the same sleep stages (total duration of slow wave and control segments: 49 min each). During the slow waves, spikes and high frequency oscillations were more frequent than during control segments (79% of spikes during slow waves and 65% of high frequency oscillations, both P ∼ 0). The spike and high frequency oscillation density also increased for higher amplitude slow waves. We compared the density of spikes and high frequency oscillations between the 'up' and 'down' states. Spike and high frequency oscillation density was highest during the transition from the 'up' to the 'down' state. Interestingly, high frequency oscillations in channels with normal activity expressed a different peak at the transition from the 'down' to the 'up' state. These results show that the apparent activation of epileptic discharges by non-rapid eye movement sleep is not a state-dependent phenomenon but is predominantly associated with specific events, the high amplitude widespread slow waves that are frequent, but not
Zheng-de Dai
2002-01-01
In the present paper, the existence of global attractor for dissipative Hamiltonian amplitude equation governing the modulated wave instabilities in E0 is considered. By a decomposition of solution operator, it is shown that the global attractor in E0 is actually equal to a global attractor in E1.
In search of objective manometric criteria for colonic high-amplitude propagated pressure waves
De Schryver, AMP; Samsom, M; Smout, AJPM
2002-01-01
The aims of this study were to explore all characteristics of high-amplitude propagated contractions (HAPCs) that would allow them to be distinguished from nonHAPC colonic pressure waves, and to develop computer algorithms for automated HAPC detection. Colonic manometry recordings obtained from 24 h
Scattering of gravitational radiation - Second order moments of the wave amplitude
Macquart, JP
2004-01-01
Gravitational radiation that propagates through an inhomogeneous mass distribution is subject to random gravitational tensing, or scattering, causing variations in the wave amplitude and temporal smearing of the signal. A statistical theory is constructed to treat these effects. The statistical prop
Joint Inversion for Earthquake Depths Using Local Waveforms and Amplitude Spectra of Rayleigh Waves
Jia, Zhe; Ni, Sidao; Chu, Risheng; Zhan, Zhongwen
2017-01-01
Reliable earthquake depth is fundamental to many seismological problems. In this paper, we present a method to jointly invert for centroid depths with local (distance distance of 5°-15°) Rayleigh wave amplitude spectra on sparse networks. We use earthquake focal mechanisms and magnitudes retrieved with the Cut-and-Paste (CAP) method to compute synthetic amplitude spectra of fundamental mode Rayleigh wave for a range of depths. Then we grid search to find the optimal depth that minimizes the joint misfit of amplitude spectra and local waveforms. As case studies, we apply this method to the 2008 Wells, Nevada Mw6.0 earthquake and a Mw5.6 outer-rise earthquake to the east of Japan Trench in 2013. Uncertainties estimated with a bootstrap re-sampling approach show that this joint inversion approach constrains centroid depths well, which are also verified by independent teleseismic depth-phase data.
Shock Wave Dynamics in Weakly Ionized Plasmas
Johnson, Joseph A., III
1999-01-01
An investigation of the dynamics of shock waves in weakly ionized argon plasmas has been performed using a pressure ruptured shock tube. The velocity of the shock is observed to increase when the shock traverses the plasma. The observed increases cannot be accounted for by thermal effects alone. Possible mechanisms that could explain the anomalous behavior include a vibrational/translational relaxation in the nonequilibrium plasma, electron diffusion across the shock front resulting from high electron mobility, and the propagation of ion-acoustic waves generated at the shock front. Using a turbulence model based on reduced kinetic theory, analysis of the observed results suggest a role for turbulence in anomalous shock dynamics in weakly ionized media and plasma-induced hypersonic drag reduction.
Inductance of rf-wave-heated plasmas.
Farshi, E; Todo, Y
2003-03-14
The inductance of rf-wave-heated plasmas is derived. This inductance represents the inductance of fast electrons located in a plateau during their acceleration due to electric field or deceleration due to collisions and electric field. This inductance has been calculated for small electric fields from the two-dimensional Fokker-Planck equation as the flux crossing the surface of critical energy mv(2)(ph)/2 in the velocity space. The new expression may be important for radio-frequency current drive ramp-up, current drive efficiency, current profile control, and so on in tokamaks. This inductance may be incorporated into transport codes that study plasma heating by rf waves.
Large-amplitude ion-acoustic double layers in multispecies plasma
Jain, S. L.; Tiwari, R. S.; Sharma, S. R.
1990-06-01
The effect of second-ion species on the characteristics of large-amplitude ion-acoustic double layers (IADL) in a collisionless, unmagnetized plasma (consisting of hot and cold Maxwellian populations of electrons and two cold-ion species with different masses, concentrations, and charge states) is investigated. After deriving the criteria for the existence of large-amplitude IADL, it is found that the presence of a positive-ion impurity does not considerably modify the characteristics of large-amplitude IADL. However, the presence of negative-ion impurity significantly changes the characteristics of a large-amplitude IADL. An analytic discussion of small-amplitude IADL using a reductive perturbation method is also presented.
Abdilghanie, Ammar M.; Diamessis, Peter J.
2012-01-01
Numerical simulations of internal gravity wave (IGW) dynamics typically rely on wave velocity and density fields which are either generated through forcing terms in the governing equations or are explicitly introduced as initial conditions. Both approaches are based on the associated solution to the inviscid linear internal wave equations and, thus, assume weak-amplitude, space-filling waves. Using spectral multidomain-based numerical simulations of the two-dimensional Navier-Stokes equations and focusing on the forcing-driven approach, this study examines the generation and subsequent evolution of large-amplitude IGW packets which are strongly localized in the vertical in a linearly stratified fluid. When the vertical envelope of the forcing terms varies relatively rapid when compared to the vertical wavelength, the associated large vertical gradients in the Reynolds stress field drive a nonpropagating negative horizontal mean flow component in the source region. The highly nonlinear interaction of this mean current with the propagating IGW packet leads to amplification of the wave, a significant distortion of its rear flank, and a substantial decay of its amplitude. Scaling arguments show that the mean flow is enhanced with a stronger degree of localization of the forcing, larger degree of hydrostaticity, and increasing wave packet steepness. Horizontal localization results in a pronounced reduction in mean flow strength mainly on account of the reduced vertical gradient of the wave Reynolds stress. Finally, two techniques are proposed toward the efficient containment of the mean flow at minimal computational cost. The findings of this study are of particular value in overcoming challenges in the design of robust computational process studies of IGW packet (or continuously forced wave train) interactions with a sloping boundary, critical layer, or caustic, where large wave amplitudes are required for any instabilities to develop. In addition, the detailed
Hafez, M. G.; Talukder, M. R.
2015-09-01
This work investigates the theoretical and numerical studies on nonlinear propagation of ion acoustic solitary waves (IASWs) in an unmagnetized plasma consisting of nonextensive electrons, Boltzmann positrons and relativistic thermal ions. The Korteweg-de Vries (KdV) equation is derived by using the well known reductive perturbation method. This equation admits the soliton like solitary wave solution. The effects of phase velocity, amplitude of soliton, width of soliton and electrostatic nonlinear propagation of weakly relativistic ion-acoustic solitary waves have been discussed with graphical representation found in the variation of the plasma parameters. The obtained results can be helpful in understanding the features of small but finite amplitude localized relativistic ion-acoustic waves for an unmagnetized three component plasma system in astrophysical compact objects.
Local finite-amplitude wave activity as an objective diagnostic of midlatitude extreme weather
Chen, Gang; Lu, Jian; Burrows, Alex D.; Leung, Lai-Yung R.
2015-12-28
Midlatitude extreme weather events are responsible for a large part of climate related damage, yet our understanding of these extreme events is limited, partly due to the lack of a theoretical basis for midlatitude extreme weather. In this letter, the local finite-amplitude wave activity (LWA) of Huang and Nakamura [2015] is introduced as a diagnostic of the 500-hPa geopotential height (Z500) to characterizing midlatitude weather events. It is found that the LWA climatology and its variability associated with the Arctic Oscillation (AO) agree broadly with the previously reported blocking frequency in literature. There is a strong seasonal and spatial dependence in the trend13 s of LWA in recent decades. While there is no observational evidence for a hemispheric-scale increase in wave amplitude, robust trends in wave activity can be identified at the regional scales, with important implications for regional climate change.
Wilson, Lynn B., III
2010-01-01
We present a statistical study of the characteristics of electron distributions associated with large amplitude whistler waves inside the terrestrial magnetosphere using waveform capture data as an addition of the study by Kellogg et al., [2010b]. We identified three types of electron distributions observed simultaneously with the whistler waves including beam-like, beam/flattop, and anisotropic distributions. The whistlers exhibited different characteristics dependent upon the observed electron distributions. The majority of the waveforms observed in our study have f/fce or = 8 nT pk-pk) whistler wave measured in the radiation belts. The majority of the largest amplitude whistlers occur during magnetically active periods (AE > 200 nT).
Nehmetallah, George; Banerjee, Partha; Khoury, Jed
2015-11-10
This work comprises the theoretical and numerical validations of experimental work on pattern and defect detection of periodic amplitude and phase structures using four-wave mixing in photorefractive materials. The four-wave mixing optical processor uses intensity filtering in the Fourier domain. Specifically, the nonlinear transfer function describing four-wave mixing is modeled, and the theory for detection of amplitude and phase defects and dislocations are developed. Furthermore, numerical simulations are performed for these cases. The results show that this technique successfully detects the slightest defects clearly even with no prior enhancement. This technique should prove to be useful in quality control systems, production-line defect inspection, and e-beam lithography.
Prestimulus amplitudes modulate P1 latencies and evoked traveling alpha waves
Nicole Alexandra Himmelstoss
2015-05-01
Full Text Available Traveling waves have been well documented in the ongoing, and more recently also in the evoked EEG. In the present study we investigate what kind of physiological process might be responsible for inducing an evoked traveling wave. We used a semantic judgment task which already proved useful to study evoked traveling alpha waves that coincide with the appearance of the P1 component. We found that the P1 latency of the leading electrode is significantly correlated with prestimulus amplitude size and that this event is associated with a transient change in alpha frequency. We assume that cortical background excitability, as reflected by an increase in prestimulus amplitude, is responsible for the observed change in alpha frequency and the initiation of an evoked traveling trajectory.
Non-Linear High Amplitude Oscillations in Wave-shaped Resonators
Antao, Dion; Farouk, Bakhtier
2011-11-01
A numerical and experimental study of non-linear, high amplitude standing waves in ``wave-shaped'' resonators is reported here. These waves are shock-less and can generate peak acoustic overpressures that can exceed the ambient pressure by three/four times its nominal value. A high fidelity compressible axisymmetric computational fluid dynamic model is used to simulate the phenomena in cylindrical and arbitrarily shaped axisymmetric resonators. Working fluids (Helium, Nitrogen and R-134a) at various operating pressures are studied. The experiments are performed in a constant cross-section cylindrical resonator in atmospheric pressure nitrogen and helium to provide model validation. The high amplitude non-linear oscillations demonstrated can be used as a prime mover in a variety of applications including thermoacoustic cryocooling. The work reported is supported by the US National Science Foundation under grant CBET-0853959.
Large amplitude, leaky, island-generated, internal waves around Palau, Micronesia
Wolanski, E.; Colin, P.; Naithani, J.; Deleersnijder, E.; Golbuu, Y.
2004-08-01
Three years of temperature data along two transects extending to 90 m depth, at Palau, Micronesia, show twice-a-day thermocline vertical displacements of commonly 50-100 m, and on one occasion 270 m. The internal wave occurred at a number of frequencies. There were a number of spectral peaks at diurnal and semi-diurnal frequencies, as well as intermediate and sub-inertial frequencies, less so at the inertial frequency. At Palau the waves generally did not travel around the island because there was no coherence between internal waves on either side of the island. The internal waves at a site 30 km offshore were out-of-phase with those on the island slopes, suggesting that the waves were generated on the island slope and then radiated away. Palau Island was thus a source of internal wave energy for the surrounding ocean. A numerical model suggests that the tidal and low-frequency currents flowing around the island form internal waves with maximum wave amplitude on the island slope and that these waves radiate away from the island. The model also suggests that the headland at the southern tip of Palau prevents the internal waves to rotate around the island. The large temperature fluctuations (commonly daily fluctuations ≈10 °C, peaking at 20 °C) appear responsible for generating a thermal stress responsible for a biologically depauperate biological community on the island slopes at depths between 60 and 120 m depth.
Collisional Drift Waves in Stellarator Plasmas
J.L.V. Lewandowski
2003-10-07
A computational study of resistive drift waves in the edge plasma of a stellarator with an helical magnetic axis is presented. Three coupled field equations, describing the collisional drift wave dynamics in the linear approximation, are solved as an initial-value problem along the magnetic field line. The magnetohydrodynamic equilibrium is obtained from a three-dimensional local equilibrium model. The use of a local magnetohydrodynamic equilibrium model allows for a computationally efficient systematic study of the impact of the magnetic field structure on drift wave stability.
On the freak waves in mesospheric plasma
El-Labany, S. K.; El-Shewy, E. K.; El-Bedwehy, N. A.; El-Razek, H. N. Abd; El-Rahman, A. A.
2017-03-01
The nonlinear properties of dusty ionic freak waves have been studied in homogeneous, unmagnetized dusty plasma system containing ions, isothermal electrons, negative and positive grains. By using the derivative expansion method and assuming strongly dispersive medium, the basic model equations are reduced to a nonlinear form of Schrodinger equation (NLSE). One of the solutions of the NLSE in the unstable region is the rational one which is responsible for the creation of the freak profiles. The reliance of freak waves profile on dusty grains charge and carrier wave number are discussed.
Plasma shock waves excited by THz radiation
Rudin, S.; Rupper, G.; Shur, M.
2016-10-01
The shock plasma waves in Si MOS, InGaAs and GaN HEMTs are launched at a relatively small THz power that is nearly independent of the THz input frequency for short channel (22 nm) devices and increases with frequency for longer (100 nm to 1 mm devices). Increasing the gate-to-channel separation leads to a gradual transition of the nonlinear waves from the shock waves to solitons. The mathematics of this transition is described by the Korteweg-de Vries equation that has the single propagating soliton solution.
The Potential for Ambient Plasma Wave Propulsion
Gilland, James H.; Williams, George J.
2016-01-01
A truly robust space exploration program will need to make use of in-situ resources as much as possible to make the endeavor affordable. Most space propulsion concepts are saddled with one fundamental burden; the propellant needed to produce momentum. The most advanced propulsion systems currently in use utilize electric and/or magnetic fields to accelerate ionized propellant. However, significant planetary exploration missions in the coming decades, such as the now canceled Jupiter Icy Moons Orbiter, are restricted by propellant mass and propulsion system lifetimes, using even the most optimistic projections of performance. These electric propulsion vehicles are inherently limited in flexibility at their final destination, due to propulsion system wear, propellant requirements, and the relatively low acceleration of the vehicle. A few concepts are able to utilize the environment around them to produce thrust: Solar or magnetic sails and, with certain restrictions, electrodynamic tethers. These concepts focus primarily on using the solar wind or ambient magnetic fields to generate thrust. Technically immature, quasi-propellantless alternatives lack either the sensitivity or the power to provide significant maneuvering. An additional resource to be considered is the ambient plasma and magnetic fields in solar and planetary magnetospheres. These environments, such as those around the Sun or Jupiter, have been shown to host a variety of plasma waves. Plasma wave propulsion takes advantage of an observed astrophysical and terrestrial phenomenon: Alfven waves. These are waves that propagate in the plasma and magnetic fields around and between planets and stars. The generation of Alfven waves in ambient magnetic and plasma fields to generate thrust is proposed as a truly propellantless propulsion system which may enable an entirely new matrix of exploration missions. Alfven waves are well known, transverse electromagnetic waves that propagate in magnetized plasmas at
Plasma wave instabilities in nonequilibrium graphene
Aryal, Chinta M.; Hu, Ben Yu-Kuang; Jauho, Antti-Pekka
2016-01-01
We study two-stream instabilities in a nonequilibrium system in which a stream of electrons is injected into doped graphene. As with equivalent nonequilibrium parabolic band systems, we find that the graphene systems can support unstable charge-density waves whose amplitudes grow with time. We...... of the injected electrons that maximizes the growth rate increases with increasing | q |. We compare the range and strength of the instability in graphene to that of two- and three-dimensional parabolic band systems....
Intermittent large amplitude internal waves observed in Port Susan, Puget Sound
Harris, J. C.; Decker, L.
2017-07-01
A previously unreported internal tidal bore, which evolves into solitary internal wave packets, was observed in Port Susan, Puget Sound, and the timing, speed, and amplitude of the waves were measured by CTD and visual observation. Acoustic Doppler current profiler (ADCP) measurements were attempted, but unsuccessful. The waves appear to be generated with the ebb flow along the tidal flats of the Stillaguamish River, and the speed and width of the resulting waves can be predicted from second-order KdV theory. Their eventual dissipation may contribute significantly to surface mixing locally, particularly in comparison with the local dissipation due to the tides. Visually the waves appear in fair weather as a strong foam front, which is less visible the farther they propagate.
Plasma acceleration by the interaction of parallel propagating Alfv\\'en waves
Mottez, Fabrice
2014-01-01
It is shown that two circularly polarised Alfv\\'en waves that propagate along the ambient magnetic field in an uniform plasma trigger non oscillating electromagnetic field components when they cross each other. The non-oscilliating field components can accelerate ions and electrons with great efficiency. This work is based on particle-in-cell (PIC) numerical simulations and on analytical non-linear computations. The analytical computations are done for two counter-propagating monochromatic waves. The simulations are done with monochromatic waves and with wave packets. The simulations show parallel electromagnetic fields consistent with the theory, and they show that the particle acceleration result in plasma cavities and, if the waves amplitudes are high enough, in ion beams. These acceleration processes could be relevant in space plasmas. For instance, they could be at work in the auroral zone and in the radiation belts of the Earth magnetosphere. In particular, they may explain the origin of the deep plasma...
Large amplitude ion-acoustic double layers in warm dusty plasma
Jain, S. L.; Tiwari, R. S.; Mishra, M. K.
2015-01-01
Large amplitude ion-acoustic double layer (IADL) is studied using Sagdeev's pseudo-potential technique in collisionless unmagnetized plasma comprising hot and cold Maxwellian population of electrons, warm adiabatic ions, and dust grains. Variation of both Mach number (M) and amplitude |φ m | of large amplitude IADL with charge, concentration, and mass of heavily charged massive dust grains is investigated for both positive and negative dust in plasma. Our numerical analysis shows that system supports only rarefactive large amplitude IADL for the selected set of plasma parameters. Our investigations for both negative and positive dust grains reveal that ion temperature increases the mobility of ions, resulting in increase in the Mach number of IADL. The larger mobility of ions causes leakage of ions from localized region, resulting into decrease in the amplitude of IADL. Other parameters, e.g. temperature ratio of hot to cold electrons, charge, concentration, mass of heavily charged massive dust grains also play significant role in the properties and existence of double layers. Since it is well established that both positive and negative dust are found in space as well as laboratory plasma, and double layers have a tremendous role to play in astrophysics, we have included both positive and negative dust in our numerical analysis for the study of large amplitude IADL. Further data used for negative dust are close to experimentally observed data. Hence, it is anticipated that our parametric studies for heavily charged (both positive and negative) dust may be useful in understanding laboratory plasma experiments, identifying nonlinear structures in upper part of ionosphere and lower part of magnetosphere structures, and in theoretical research for the study of properties of nonlinear structures.
Solitons and Weakly Nonlinear Waves in Plasmas
Pécseli, Hans
1985-01-01
Theoretical descriptions of solitons and weakly nonlinear waves propagating in plasma media are reviewed, with particular attention to the Korteweg-de Vries (KDV) equation and the Nonlinear Schrödinger equation (NLS). The modifications of these basic equations due to the effects of resonant...
A P Misra; A Roy Chowdhury; S N Paul
2004-09-01
Characteristic features of low frequency transverse wave propagating in a magnetised dusty plasma have been analysed considering the effect of dust-charge fluctuation. The distinctive behaviours of both the left circularly polarised and right circularly polarised waves have been exhibited through the analysis of linear and non-linear dispersion relations. The phase velocity, group velocity, and group travel time for the waves have been obtained and their propagation characteristics have been shown graphically with the variations of wave frequency, dust density and amplitude of the wave. The change in non-linear wave number shift and Faraday rotation angle have also been exhibited with respect to the plasma parameters. It is observed that the effects of dust particles are significant only when the higher order contributions are considered. This may be referred to as the `dust regime' in plasma.
Analysis for the amplitude oscillatory movements of the ship in response to the incidence wave
Chiţu, M. G.; Zăgan, R.; Manea, E.
2015-11-01
Event of major accident navigation near offshore drilling rigs remains unacceptably high, known as the complications arising from the problematic of the general motions of the ship sailing under real sea. Dynamic positioning system is an effective instrument used on board of the ships operating in the extraction of oil and gas in the continental shelf of the seas and oceans, being essential that the personnel on board of the vessel can maintain position and operating point or imposed on a route with high precision. By the adoption of a strict safety in terms of handling and positioning of the vessel in the vicinity of the drilling platform, the risk of accidents can be reduced to a minimum. Possibilities in anticipation amplitudes of the oscillatory movements of the ships navigating in real sea, is a challenge for naval architects and OCTOPUS software is a tool used increasingly more in this respect, complementing navigational facilities offered by dynamic positioning systems. This paper presents a study on the amplitudes of the oscillations categories of supply vessels in severe hydro meteorological conditions of navigation. The study provides information on the RAO (Response Amplitude Operator) response operator of the ship, for the amplitude of the roll movements, in some incident wave systems, interpreted using the energy spectrum Jonswap and whose characteristics are known (significant height of the wave, wave period, pulsation of the wave). Ship responses are analyzed according to different positioning of the ship in relation to the wave front (incident angle ranging from 10 to 10 degree from 0 to 180), highlighting the value of the ship roll motion amplitude. For the study, was used, as a tool for modeling and simulation, the features offered by OCTOPUS software that allows the study of the computerized behavior of the ship on the waves, in the real conditions of navigation. Program library was used for both the vessel itself and navigation modeling
Role of the Ionosphere in the Generation of Large-Amplitude Ulf Waves at High Latitudes
Tulegenov, B.; Guido, T.; Streltsov, A. V.
2014-12-01
We present results from the statistical study of ULF waves detected by the fluxgate magnetometer in Gakona, Alaska during several experimental campaigns conducted at the High Frequency Active Auroral Research Program (HAARP) facility in years 2011-2013. We analyzed frequencies of ULF waves recorded during 26 strongly disturbed geomagnetic events (substorms) and compared them with frequencies of ULF waves detected during magnetically quite times. Our analysis demonstrates that the frequency of the waves carrying most of the power almost in all these events is less than 1 mHz. We also analyzed data from the ACE satellite, measuring parameters of the solar wind in the L1 Lagrangian point between Earth and Sun, and found that in several occasions there is a strong correlation between oscillations of the magnetic field in the solar wind and oscillations detected on the ground. We also found several cases when there is no correlation between signals detected on ACE and on the ground. This finding suggests that these frequencies correspond to the fundamental eigenfrequency of the coupled magnetosphere-ionosphere system. The low frequency of the oscillations is explained by the effect of the ionosphere, where the current is carried by ions through highly collisional media. The amplitude of these waves can reach significant magnitude when the system is driven by the external driver (for example, the solar wind) with this particular frequency. When the frequency of the driver does not match the frequency of the system, the waves still are observed, but their amplitudes are much smaller.
Dispersion relations with crossing symmetry for pipi D and F wave amplitudes
Kaminski, R.
2011-01-01
A set of once subtracted dispersion relations with imposed crossing symmetry condition for the pipi D- and F-wave amplitudes is derived and analyzed. An example of numerical calculations in the effective two pion mass range from the threshold to 1.1 GeV is presented. It is shown that these new dispersion relations impose quite strong constraints on the analyzed pipi interactions and are very useful tools to test the pipi amplitudes. One of the goals of this work is to provide a complete set o...
Large-amplitude double layers in a dusty plasma with an arbitrary streaming ion beam
Brindaban Das; Debkumar Ghosh; Prasanta Chatterjee
2010-06-01
Formation of large-amplitude double layers in a dusty plasma whose constituents are electrons, ions, warm dust grains and positive ion beam are studied using Sagdeev’s pseudopotential technique. Existence of double layers is investigated. It is found that both the temperature of dust particles and ion beam temperature play significant roles in determining the region of the existence of double layers.
A model for large-amplitude internal solitary waves with trapped cores
K. R. Helfrich
2010-07-01
Full Text Available Large-amplitude internal solitary waves in continuously stratified systems can be found by solution of the Dubreil-Jacotin-Long (DJL equation. For finite ambient density gradients at the surface (bottom for waves of depression (elevation these solutions may develop recirculating cores for wave speeds above a critical value. As typically modeled, these recirculating cores contain densities outside the ambient range, may be statically unstable, and thus are physically questionable. To address these issues the problem for trapped-core solitary waves is reformulated. A finite core of homogeneous density and velocity, but unknown shape, is assumed. The core density is arbitrary, but generally set equal to the ambient density on the streamline bounding the core. The flow outside the core satisfies the DJL equation. The flow in the core is given by a vorticity-streamfunction relation that may be arbitrarily specified. For simplicity, the simplest choice of a stagnant, zero vorticity core in the frame of the wave is assumed. A pressure matching condition is imposed along the core boundary. Simultaneous numerical solution of the DJL equation and the core condition gives the exterior flow and the core shape. Numerical solutions of time-dependent non-hydrostatic equations initiated with the new stagnant-core DJL solutions show that for the ambient stratification considered, the waves are stable up to a critical amplitude above which shear instability destroys the initial wave. Steadily propagating trapped-core waves formed by lock-release initial conditions also agree well with the theoretical wave properties despite the presence of a "leaky" core region that contains vorticity of opposite sign from the ambient flow.
Nguyen, Nam Q.; Tippett, Marcus; Smout, Andre J. P. M.; Holloway, Richard H.
2006-01-01
OBJECTIVES: Esophageal wave amplitude is an important determinant of esophageal clearance. A threshold of 30 mmHg is widely accepted as the threshold for effective clearance in the distal esophagus. However, the precise relationship between wave amplitude and clearance has received relatively little
Mithaiwala, Manish; Crabtree, Chris; Ganguli, Gurudas
2012-01-01
It is shown that the dispersion relation for whistler waves is identical for a high or low beta plasma. Furthermore in the high-beta solar wind plasma whistler waves meet the Landau resonance with electrons for velocities less than the thermal speed, and consequently the electric force is small compared to the mirror force. As whistlers propagate through the inhomogeneous solar wind, the perpendicular wave number increases through refraction, increasing the Landau damping rate. However, the whistlers can survive because the background kinetic Alfven wave turbulence creates a plateau by quasilinear diffusion in the solar wind electron distribution at small velocities. It is found that for whistler energy density of only ~10^-3 that of the kinetic Alfven waves, the quasilinear diffusion rate due to whistlers is comparable to KAW. Thus very small amplitude whistler turbulence can have a significant consequence on the evolution of the solar wind electron distribution function.
O'Grady, G; Du, P; Paskaranandavadivel, N; Angeli, T R; Lammers, W J E P; Asirvatham, S J; Windsor, J A; Farrugia, G; Pullan, A J; Cheng, L K
2012-07-01
Gastric slow waves propagate aborally as rings of excitation. Circumferential propagation does not normally occur, except at the pacemaker region. We hypothesized that (i) the unexplained high-velocity, high-amplitude activity associated with the pacemaker region is a consequence of circumferential propagation; (ii) rapid, high-amplitude circumferential propagation emerges during gastric dysrhythmias; (iii) the driving network conductance might switch between interstitial cells of Cajal myenteric plexus (ICC-MP) and circular interstitial cells of Cajal intramuscular (ICC-IM) during circumferential propagation; and (iv) extracellular amplitudes and velocities are correlated. An experimental-theoretical study was performed. High-resolution gastric mapping was performed in pigs during normal activation, pacing, and dysrhythmia. Activation profiles, velocities, and amplitudes were quantified. ICC pathways were theoretically evaluated in a bidomain model. Extracellular potentials were modeled as a function of membrane potentials. High-velocity, high-amplitude activation was only recorded in the pacemaker region when circumferential conduction occurred. Circumferential propagation accompanied dysrhythmia in 8/8 experiments was faster than longitudinal propagation (8.9 vs 6.9 mm s(-1) ; P = 0.004) and of higher amplitude (739 vs 528 μV; P = 0.007). Simulations predicted that ICC-MP could be the driving network during longitudinal propagation, whereas during ectopic pacemaking, ICC-IM could outpace and activate ICC-MP in the circumferential axis. Experimental and modeling data demonstrated a linear relationship between velocities and amplitudes (P propagation. Rapid circumferential propagation also emerges during a range of gastric dysrhythmias, elevating extracellular amplitudes and organizing transverse wavefronts. One possible explanation for these findings is bidirectional coupling between ICC-MP and circular ICC-IM networks. © 2012 Blackwell Publishing Ltd.
Stability of steady rotational water-waves of finite amplitude on arbitrary shear currents
Seez, William; Abid, Malek; Kharif, Christian
2016-04-01
A versatile solver for the two-dimensional Euler equations with an unknown free-surface has been developed. This code offers the possibility to calculate two-dimensional, steady rotational water-waves of finite amplitude on an arbitrary shear current. Written in PYTHON the code incorporates both pseudo-spectral and finite-difference methods in the discretisation of the equations and thus allows the user to capture waves with large steepnesses. As such it has been possible to establish that, in a counter-flowing situation, the existence of wave solutions is not guaranteed and depends on a pair of parameters representing mass flux and vorticity. This result was predicted, for linear solutions, by Constantin. Furthermore, experimental comparisons, both with and without vorticity, have proven the precision of this code. Finally, waves propagating on top of highly realistic shear currents (exponential profiles under the surface) have been calculated following current profiles such as those used by Nwogu. In addition, a stability analysis routine has been developed to study the stability regimes of base waves calculated with the two-dimensional code. This linear stability analysis is based on three dimensional perturbations of the steady situation which lead to a generalised eigenvalue problem. Common instabilities of the first and second class have been detected, while a third class of wave-instability appears due to the presence of strong vorticity. {1} Adrian Constantin and Walter Strauss. {Exact steady periodic water waves with vorticity}. Communications on Pure and Applied Mathematics, 57(4):481-527, April 2004. Okey G. Nwogu. {Interaction of finite-amplitude waves with vertically sheared current fields}. Journal of Fluid Mechanics, 627:179, May 2009.
Orozco-Santillán, Arturo; Ruiz-Boullosa, Ricardo; Cutanda Henríquez, Vicente
2007-01-01
published on the topic predicts that these instabilities appear when the levitator is driven with a frequency above the resonant frequency of the empty device. The theory also shows that the instabilities can either saturate to a state with constant amplitude, or they can grow without limit until the object...... pressure amplitude in the cavity because of the presence of the sample. The theory predicts that the phase difference depends on the speed of the oscillating object. In this paper, we give for the first time experimental evidence that shows the existence of the phase difference, and that it is negatively...... proportional to the oscillation frequency of the levitated sample. We also present experimental results that show that the oscillational instabilities can be reduced if the amplitude of the acoustic wave is increased; as a result, stable conditions can be obtained where the oscillations of the sphere...
唐登斌; 夏浩
2002-01-01
The nonlinear evolution problem in nonparallel boundary layer stability was studied. The relative parabolized stability equations of nonlinear nonparallel boundary layer were derived. The developed numerical method, which is very effective, was used to study the nonlinear evolution of T-S disturbance wave at finite amplitudes. Solving nonlinear equations of different modes by using predictor-corrector and iterative approach, which is uncoupled between modes, improving computational accuracy by using high order compact differential scheme, satisfying normalization condition, determining tables of nonlinear terms at different modes, and implementing stably the spatial marching, were included in this method. With different initial amplitudes, the nonlinear evolution of T-S wave was studied. The nonlinear nonparallel results of examples compare with data of direct numerical simulations (DNS) using full Navier- Stokes equations.
Electron Bernstein Wave Emission from RFP Plasmas
Nornberg, M. D.; Thomas, M.; Anderson, J.; Forest, C. B.
1998-11-01
Electron cyclotron emission (ECE) has proven to be a powerfull diagnostic tool in tokamak plasmas for determining the time evolution of the electron temperature profile. The standard technique of observing O-mode or X-mode electromagnetic waves normal to the magnetic field is not applicable to reversed field pinch (RFP) plasmas since the plasma frequency is much larger than the electron cyclotron frequency. We are investigating the use of electron Bernstein waves (presumed to be in thermal equilibrium with the electrons) through the aip.org/journal_cgi/ getpdf?KEY=PRLTAO&cvips=PRLTAO000078000018003467000001>O-X-B mode conversion process. At oblique incidence, the evanescent layer separating the plamsa cutoff from the cyclotron cutoff vanishes, allowing conversion of the Bernstein mode waves to the extraordinary mode and finally to the ordinary mode. The O-mode radiation is received by a phased array antenna consisting of two waveguides on the edge of the plasma, and the spectrum of emitted radiation is measured using a radiometer spanning 4-8 GHz. In addition to providing information about the electron temperature profile, the spectrum can provide a novel method of measuring the central magnetic field strength for current profile reconstructions.
Bukchin, B. G.
1995-08-01
A special case of the seismic source, where the stress glut tensor can be expressed as a product of a uniform moment tensor and a scalar function of spatial coordinates and time, is considered. For such a source, a technique of determining stress glut moments of total degree 2 from surface wave amplitude spectra is described. The results of application of this technique for the estimation of spatio-temporal characteristics of the Georgian earthquake, 29.04.91 are presented.
Beat-to-beat T-wave amplitude variability in the long QT syndrome.
Extramiana, Fabrice; Tatar, Charif; Maison-Blanche, Pierre; Denjoy, Isabelle; Messali, Anne; Dejode, Patrick; Iserin, Frank; Leenhardt, Antoine
2010-09-01
Long QT syndrome (LQTS) is a primary electrical disease characterized by QT prolongation and increased repolarization dispersion leading to T-wave amplitude beat-to-beat changes. We aimed to quantify beat-to-beat T-wave amplitude variability from ambulatory Holter recordings in genotyped LQTS patients. Seventy genotyped LQTS patients (mean age 23 +/- 15 years, 42 males, 50% LQT1, 39% LQT2, and 11% LQT3) and 70 normal matched control subjects underwent a 24-h digital Holter recording. Using the Tvar software (Ela Medical, Sorin group), the beat-to-beat variance of the T-wave amplitude (TAV in microV) [corrected] was assessed on 50-ms consecutive clusters during three 1-h periods: one with around average diurnal heart rate (Day Fast), one nocturnal period (Night), and one diurnal period with around average nocturnal heart rate (Day Slow). TAV was increased in LQTS patients during the two diurnal periods but not at night (during the Day Fast period, mean TAV was 34 +/- 20 microV [corrected] in LQTS patients vs. 27 +/- 10 microV [corrected] in controls, P < 0.05). This effect depended on the genotype. In LQT1, TAV was larger when compared with controls for both Day Fast and Slow periods, but in LQT2 only Day Fast shows higher TAV. Oppositely, in LQT3 the TAV was higher than in the control group during the Day slow period (mean TAV = 34 +/- 20 vs. 25 +/- 8 microV [corrected] in controls, P < 0.05). In genotyped LQTS patients beat-to-beat T-wave amplitude variability was increased when compared with control subjects. That pattern was modulated by circadian influences in a gene-dependent manner.
Plasma Limiter Based on Surface Wave Plasma Excited by Microwave
YANG Geng; TAN Jichun; SHEN Benjian
2008-01-01
A novel plasma limiter, in which the plasma is excited by surface wave, is presented. The breakdown time of some gases filled in the limiter were calculated as a function of gas pres-sure, ionization degree and density of seed electrons under low pressure (0.01 ～1 Torr) and high pressure (10 ～1000 Torr) cases. The results show that the limiter filled with Xe with a pressure of 0.9 Torr, seed electron density of 1016 m-3, and ionization degree of 10-4, has a breakdown time of approximate 19.6 ns.
High amplitude nonlinear acoustic wave driven flow fields in cylindrical and conical resonators.
Antao, Dion Savio; Farouk, Bakhtier
2013-08-01
A high fidelity computational fluid dynamic model is used to simulate the flow, pressure, and density fields generated in a cylindrical and a conical resonator by a vibrating end wall/piston producing high-amplitude standing waves. The waves in the conical resonator are found to be shock-less and can generate peak acoustic overpressures that exceed the initial undisturbed pressure by two to three times. A cylindrical (consonant) acoustic resonator has limitations to the output response observed at one end when the opposite end is acoustically excited. In the conical geometry (dissonant acoustic resonator) the linear acoustic input is converted to high energy un-shocked nonlinear acoustic output. The model is validated using past numerical results of standing waves in cylindrical resonators. The nonlinear nature of the harmonic response in the conical resonator system is further investigated for two different working fluids (carbon dioxide and argon) operating at various values of piston amplitude. The high amplitude nonlinear oscillations observed in the conical resonator can potentially enhance the performance of pulse tube thermoacoustic refrigerators and these conical resonators can be used as efficient mixers.
A nonlinear model for magnetoacoustic waves in dense dissipative plasmas with degenerate electrons
Masood, W. [COMSATS Institute of Information Technology, Islamabad (Pakistan); National Centre for Physics (NCP), Shahdra Valley Road, Islamabad (Pakistan); Jahangir, R.; Siddiq, M. [National Centre for Physics (NCP), Shahdra Valley Road, Islamabad (Pakistan); Eliasson, B. [SUPA, Physics Department, University of Strathclyde, Glasgow (United Kingdom)
2014-10-15
The properties of nonlinear fast magnetoacoustic waves in dense dissipative plasmas with degenerate electrons are studied theoretically in the framework of the Zabolotskaya-Khokhlov (ZK) equation for small but finite amplitude excitations. Shock-like solutions of the ZK equation are obtained and are applied to parameters relevant to white dwarf stars.
Microwave beatwave excitation of electron plasma wave and high energy electron production
Yatsuzuka, M.; Obata, K.; Nobuhara, S. [Himeji Inst. of Tech., Hyogo (Japan)
1997-12-31
Two X-band microwave beams with a slightly different frequency and the maximum output power of 50 kW are injected into a target plasma antiparallel to each other through a standard horn. The resonant excitation of an electron plasma wave is observed when the difference in frequency between counterstreaming microwaves is equal to the electron plasma frequency. The excited wave propagates in the same direction as the higher-frequency microwave with a wave length which satisfies the resonance condition of wave number. The wave amplitude grows with an increase in incident microwave power, and reaches the density perturbation {delta}n/n{sub 0} of approximately 3.2 % at the incident microwave power of 40 kW and beat frequency of 600 MHz. A small amount of high-energy electrons with the speed of 27 eV are observed in the high-power region of incident microwave. (author)
DETERMINATION OF COORDINATES OF SEISMIC WAVE SOURCE BY AMPLITUDE METHOD OF PASSIVE LOCATION
Vasily D. Syten’ky
2015-10-01
Full Text Available The paper presents results of the mathematical synthesis of the method of passive location of a seismic wave source. The method employs measurements of regular attenuation of seismic oscillation amplitudes. If it is impossible to determine the location of a seismic event by means of direct measurements, indirect measurements are needed. A priori information for the mathematical synthesis was obtained from functional equations showing inverse proportions of measured amplitudes, arbitrary effective attenuation coefficients and corresponding coordinates. An original method was applied to process the data. The method providing for passive location of seismic waves sources has been developed; it is called the radial basic method. In the one-dimensional case, a distance is determined on the basis of seismic oscillation amplitudes measured by two seismographs that are located at a known base distance coinciding with the direction to the source of seismic waves. The distance is calculated from the receiver that is nearest to the source. If the base distance and the direct line between the seismograph and the seismic wave source do not coincide, a projection of the distance between the receivers to the given straight line is taken into account.Three seismographs were placed at mutually perpendicular base distances in a plane (i.e. the two-dimensional space. This allowed us to obtain an analytical equation for determining the direction to the seismic wave source using measured amplitudes. The value of the angle is taken into account when calculating the distance.For the seismic wave source located in the three-dimensional space, transition equations for combined coordinate systems (i.e. the Descartes (Cartesian, at the axes of which the seismographs were placed, and the spherical coordinate systems were applied, and analytical equations were obtained for determination of coordinates, such as distance/polar radius, elevation
Solitary Kinetic Alfven Waves in a Low-β Dusty Plasma
CHEN Yin-Hua; LU Wei
2000-01-01
The nonlinear kinetic Alfven waves in a low-β(0<β<1)dusty plasma have been investigated with the fluid model of three-component plasma. The nonlinear equation governing the perturbation density of electrons in a form of the energy integral has been derived. In the approximation of small amplitude, the soliton solution for the perturbation density of electrons is found, and the characteristics of solitons in different range of plasma parameters is studied numerically. The results show that the density dip or hump can be formed in a dusty plasma for different ranges of parameters, the amplitude of density dip is enhanced and the amplitude of density hump is reduced with increasing dust grain content.
Study of nonlinear waves in astrophysical quantum plasmas
Hossen, M.R.; Mamun, A.A., E-mail: rasel.plasma@gmail.com [Department of Physics, Jahangirnagar University, Savar, Dhaka (Bangladesh)
2015-10-01
The nonlinear propagation of the electron acoustic solitary waves (EASWs) in an unmagnetized, collisionless degenerate quantum plasma system has been investigated theoretically. Our considered model consisting of two distinct groups of electrons (one of inertial non-relativistic cold electrons and other of inertialess ultrarelativistic hot electrons) and positively charged static ions. The Korteweg-de Vries (K-dV) equation has been derived by employing the reductive perturbation method and numerically examined to identify the basic features (speed, amplitude, width, etc.) of EASWs. It is shown that only rarefactive solitary waves can propagate in such a quantum plasma system. It is found that the effect of degenerate pressure and number density of hot and cold electron fluids, and positively charged static ions, significantly modify the basic features of EASWs. It is also noted that the inertial cold electron fluid is the source of dispersion for EA waves and is responsible for the formation of solitary structures. The applications of this investigation in astrophysical compact objects (viz. non-rotating white dwarfs, neutron stars, etc.) are briefly discussed. (author)
Tunable Plasma-Wave Laser Amplifier
Bromage, J.; Haberberger, D.; Davies, A.; Bucht, S.; Zuegel, J. D.; Froula, D. H.; Trines, R.; Bingham, R.; Sadler, J.; Norreys, P. A.
2016-10-01
Raman amplification is a process by which a long energetic pump pulse transfers its energy to a counter-propagating short seed pulse through a resonant electron plasma wave. Since its conception, theory and simulations have shown exciting results with up to tens of percent of energy transfer from the pump to the seed pulse. However, experiments have yet to surpass transfer efficiencies of a few percent. A review of past literature shows that largely chirped pump pulses and finite temperature wave breaking could have been the two most detrimental effects. A Raman amplification platform is being developed at the Laboratory for Laser Energetics where a combination of a high-intensity tunable seed laser with sophisticated plasma diagnostics (dynamic Thomson scattering) will make it possible to find the optimal parameter space for high-energy transfer. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.
Second-harmonic plasma response in diffusion-controlled surface-wave-sustained discharges
Stoev, L.
2008-05-01
The formation of nonlinear plasma response at the second harmonic frequency in diffusion controlled surface-wave-sustained discharges is studied theoretically. The study is aimed at estimating theoretically the ratio of the squared amplitudes of the wave field of fundamental frequency and of the resulting - from the nonlinear effects - electric field at the second harmonic frequency. The model presented is intended for further use in discharge diagnostics.
Photon counting chirped amplitude modulation lidar using an asymmetric triangular wave modulation
Zhang, Zijing; Cen, Longzhu; Zhang, Jiandong; Ma, Kun; Wang, Feng; Zhao, Yuan
2016-11-01
We propose a novel strategy of asymmetric triangular-wave modulation for photon-counting chirped amplitude modulation (PCCAM) lidar. Earlier studies use the symmetric triangle wave modulation, by which the velocity can be detected only when the Doppler shift caused by a moving target is greater than Full Width Half Maximum (FWHM) of Intermediate Frequency (IF). We use an alternative method known as the asymmetric triangular wave modulation method, in which the modulation rates of the up-ramp and the down-ramp are different. This new method avoids the overlapping of the up-ramp and the down-ramp IF peaks, and breaks the limit of the FWHM of IF peak to improve the velocity measuring sensitivity (also called the minimum detectable velocity). Finally, a proof-of-principle experiment is carried out in the laboratory. The experimental results agree well with the theoretical results and show the improvement of the minimum detectable velocity.
Geotail MCA Plasma Wave Investigation Data Analysis
Anderson, Roger R.
1997-01-01
The primary goals of the International Solar Terrestrial Physics/Global Geospace Science (ISTP/GGS) program are identifying, studying, and understanding the source, movement, and dissipation of plasma mass, momentum, and energy between the Sun and the Earth. The GEOTAIL spacecraft was built by the Japanese Institute of Space and Astronautical Science and has provided extensive measurements of entry, storage, acceleration, and transport in the geomagnetic tail and throughout the Earth's outer magnetosphere. GEOTAIL was launched on July 24, 1992, and began its scientific mission with eighteen extensions into the deep-tail region with apogees ranging from around 60 R(sub e) to more than 208 R(sub e) in the period up to late 1994. Due to the nature of the GEOTAIL trajectory which kept the spacecraft passing into the deep tail, GEOTAIL also made 'magnetopause skimming passes' which allowed measurements in the outer magnetosphere, magnetopause, magnetosheath, bow shock, and upstream solar wind regions as well as in the lobe, magnetosheath, boundary layers, and central plasma sheet regions of the tail. In late 1994, after spending nearly 30 months primarily traversing the deep tail region, GEOTAIL began its near-Earth phase. Perigee was reduced to 10 R(sub e) and apogee first to 50 R(sub e) and finally to 30 R(sub e) in early 1995. This orbit provides many more opportunities for GEOTAIL to explore the upstream solar wind, bow shock, magnetosheath, magnetopause, and outer magnetosphere as well as the near-Earth tail regions. The WIND spacecraft was launched on November 1, 1994 and the POLAR spacecraft was launched on February 24, 1996. These successful launches have dramatically increased the opportunities for GEOTAIL and the GGS spacecraft to be used to conduct the global research for which the ISTP program was designed. The measurement and study of plasma waves have made and will continue to make important contributions to reaching the ISTP/GGS goals and solving the
Ali Shan, S. [Theoretical Plasma Physics Division, PINSTECH, Nilore, 44000 Islamabad (Pakistan); National Centre For Physics (NCP), Shahdra Valley Road, 44000 Islamabad (Pakistan); Pakistan Institute of Engineering and Applied Sciences (PIEAS), Islamabad (Pakistan); El-Tantawy, S. A.; Moslem, W. M. [Department of Physics, Faculty of Science, Port Said University, Port Said 42521 (Egypt)
2013-08-15
Arbitrary amplitude ion-acoustic waves in an unmagnetized plasma consisting of cold positive ions, superthermal electrons, and positrons beam are reported. The basic set of fluid equations is reduced to an energy-balance like equation. The latter is numerically analyzed to examine the existence regions for solitary and shock waves. It is found that only solitary waves can propagate, however, the model cannot support shocks. The effects of superthermality and beam parameters (via, positrons concentration and streaming velocity) on the existence region, as well as solitary wave profile have been discussed.
Dust-acoustic solitary waves in a dusty plasma with two-temperature nonthermal ions
Zhi-Jian Zhou; Hong-Yan Wang; Kai-Biao Zhang
2012-01-01
By using reductive perturbation method, the nonlinear propagation of dust-acoustic waves in a dusty plasma (containing a negatively charged dust ﬂuid, Boltzmann distributed electrons and two-temperature nonthermal ions) is investigated. The effects of two-temperature nonthermal ions on the basic properties of small but ﬁnite amplitude nonlinear dust-acoustic waves are examined. It is found that two-temperature nonthermal ions affect the basic properties of the dust-acoustic solitary waves. It is also observed that only compressive solitary waves exist in this system.
Parametric decay of plasma waves near the upper-hybrid resonance
Dodin, I. Y.; Arefiev, A. V.
2017-03-01
An intense X wave propagating perpendicularly to dc magnetic field is unstable with respect to a parametric decay into an electron Bernstein wave and a lower-hybrid wave. A modified theory of this effect is proposed that extends to the high-intensity regime, where the instability rate γ ceases to be a linear function of the incident-wave amplitude. An explicit formula for γ is derived and expressed in terms of cold-plasma parameters. Theory predictions are in reasonable agreement with the results of the particle-in-cell simulations presented in a separate publication.
Collisional damping rates for plasma waves
Tigik, S. F.; Ziebell, L. F.; Yoon, P. H.
2016-06-01
The distinction between the plasma dynamics dominated by collisional transport versus collective processes has never been rigorously addressed until recently. A recent paper [P. H. Yoon et al., Phys. Rev. E 93, 033203 (2016)] formulates for the first time, a unified kinetic theory in which collective processes and collisional dynamics are systematically incorporated from first principles. One of the outcomes of such a formalism is the rigorous derivation of collisional damping rates for Langmuir and ion-acoustic waves, which can be contrasted to the heuristic customary approach. However, the results are given only in formal mathematical expressions. The present brief communication numerically evaluates the rigorous collisional damping rates by considering the case of plasma particles with Maxwellian velocity distribution function so as to assess the consequence of the rigorous formalism in a quantitative manner. Comparison with the heuristic ("Spitzer") formula shows that the accurate damping rates are much lower in magnitude than the conventional expression, which implies that the traditional approach over-estimates the importance of attenuation of plasma waves by collisional relaxation process. Such a finding may have a wide applicability ranging from laboratory to space and astrophysical plasmas.
Waves in relativistic electron beam in low-density plasma
Sheinman, I.; Sheinman (Chernenco, J.
2016-11-01
Waves in electron beam in low-density plasma are analyzed. The analysis is based on complete electrodynamics consideration. Dependencies of dispersion laws from system parameters are investigated. It is shown that when relativistic electron beam is passed through low-density plasma surface waves of two types may exist. The first type is a high frequency wave on a boundary between the beam and neutralization area and the second type wave is on the boundary between neutralization area and stationary plasma.
Strong electromagnetic waves in a magnetized relativistic electron-positron plasma
Yu, M.Y.; Shukla, P.K.; Rao, N.N. (Bochum Univ. (Germany, F.R.). Inst. fuer Theoretische Physik)
1984-12-01
It is shown that in a strongly magnetized relativistic electron-positron plasma, strongly localized large amplitude circularly polarized electromagnetic wave pulses exist. The localization is due to relativistic mass variation as well as ponderomotive force effects. Three types of pulses are found analytically: the sharply spiked pulse in a strongly magnetized cold plasma, the smooth pulse in a weak magnetized warm plasma, and the moderately spiked pulse for a weakly magnetized cold plasma. The physical mechanisms giving rise to these pulses are distinct for each case. Possible implications of our investigation to pulsar radiation are discussed.
The amplitudes and the structure of the charge density wave in YBCO
Kharkov, Y. A.; Sushkov, O. P.
2016-10-01
We find unknown s- and d-wave amplitudes of the recently discovered charge density wave (CDW) in underdoped cuprates. To do so we perform a combined analysis of experimental data for ortho-II YBa2Cu3Oy. The analysis includes data on nuclear magnetic resonance, resonant inelastic X-ray scattering, and hard X-ray diffraction. The amplitude of doping modulation found in our analysis is 3.5 · 10‑3 in a low magnetic field and T = 60 K, the amplitude is 6.5 · 10‑3 in a magnetic field of 30T and T = 1.3 K. The values are in units of elementary charge per unit cell of a CuO2 plane. We show that the data rule out a checkerboard pattern, and we also show that the data might rule out mechanisms of the CDW which do not include phonons.
Giesbertz, K J H
2014-01-01
Electron correlations in molecules can be divided in short range dynamical correlations, long range Van der Waals type interactions and near degeneracy static correlations. In this work we analyze how these three types of correlations can be incorporated in a simple wave function of restricted functional form consisting of an orbital product multiplied by a single correlation function $f(r_{12})$ depending on the interelectronic distance $r_{12}$. Since the three types of correlations mentioned lead to different signatures in terms of the natural orbital (NO) amplitudes in two-electron systems we make an analysis of the wave function in terms of the NO amplitudes for a model system of a diatomic molecule. In our numerical implementation we fully optimize the orbitals and the correlation function on a spatial grid without restrictions on their functional form. For the model system we can prove that none of the amplitudes vanishes and moreover that it displays a distinct sign pattern and a series of avoided cro...
Nonlinear low-frequency electrostatic wave dynamics in a two-dimensional quantum plasma
Ghosh, Samiran, E-mail: sran_g@yahoo.com [Department of Applied Mathematics, University of Calcutta, 92, Acharya Prafulla Chandra Road, Kolkata-700 009 (India); Chakrabarti, Nikhil, E-mail: nikhil.chakrabarti@saha.ac.in [Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata-700064 (India)
2016-08-15
The problem of two-dimensional arbitrary amplitude low-frequency electrostatic oscillation in a quasi-neutral quantum plasma is solved exactly by elementary means. In such quantum plasmas we have treated electrons quantum mechanically and ions classically. The exact analytical solution of the nonlinear system exhibits the formation of dark and black solitons. Numerical simulation also predicts the possible periodic solution of the nonlinear system. Nonlinear analysis reveals that the system does have a bifurcation at a critical Mach number that depends on the angle of propagation of the wave. The small-amplitude limit leads to the formation of weakly nonlinear Kadomstev–Petviashvili solitons.
Wilson, L. B., III; Cattell, C. A.; Kellogg, P. J.; Wygant, J. R.; Goetz, K.; Breneman, A.; Kersten, K.
2011-01-01
Wepresent resultsof a studyof the characteristicsof very large amplitude whistler mode waves inside the terrestrial magnetosphere at radial distances of less than 15 RE using waveform capture data from the Wind spacecraft. We observed 247 whistler mode waves with at least one electric field component (105/247 had !80 mV/m peak!to!peak amplitudes) and 66 whistler mode waves with at least one search coil magnetic field component (38/66 had !0.8 nT peak!to!peak amplitudes). Wave vectors determined from events with three magnetic field components indicate that 30/46 propagate within 20 of the ambient magnetic field, though some are more oblique (up to "50 ). No relationship was observed between wave normal angle and GSM latitude. 162/247 of the large amplitude whistler mode waves were observed during magnetically active periods (AE > 200 nT). 217 out of 247 total whistler mode waves examined were observed inside the radiation belts. We present a waveform capture with the largest whistler wave magnetic field amplitude (^8 nT peak!to!peak) ever reported in the radiation belts. The estimated Poynting flux magnitude associated with this wave is ^300 mW/m2, roughly four orders of magnitude above estimates from previous satellite measurements. Such large Poynting flux values are consistent with rapid energization of electrons.
Electrostatic Korteweg-deVries solitary waves in a plasma with Kappa-distributed electrons
Choi, C.-R.; Min, K.-W. [Department of Physics, Korea Advanced Institute of Science and Technology, Taejon 305-701 (Korea, Republic of); Rhee, T.-N. [National Fusion Research Institute, Daejeon 305-333 (Korea, Republic of)
2011-09-15
The Korteweg-deVries (KdV) equation that describes the evolution of nonlinear ion-acoustic solitary waves in plasmas with Kappa-distributed electrons is derived by using a reductive perturbation method in the small amplitude limit. We identified a dip-type (negative) electrostatic KdV solitary wave, in addition to the hump-type solution reported previously. The two types of solitary waves occupy different domains on the {kappa} (Kappa index)-V (propagation velocity) plane, separated by a curve corresponding to singular solutions with infinite amplitudes. For a given Kappa value, the dip-type solitary wave propagates faster than the hump-type. It was also found that the hump-type solitary waves cannot propagate faster than V = 1.32.
Plasma production for electron acceleration by resonant plasma wave
Anania, M. P.; Biagioni, A.; Chiadroni, E.; Cianchi, A.; Croia, M.; Curcio, A.; Di Giovenale, D.; Di Pirro, G. P.; Filippi, F.; Ghigo, A.; Lollo, V.; Pella, S.; Pompili, R.; Romeo, S.; Ferrario, M.
2016-09-01
Plasma wakefield acceleration is the most promising acceleration technique known nowadays, able to provide very high accelerating fields (10-100 GV/m), enabling acceleration of electrons to GeV energy in few centimeter. However, the quality of the electron bunches accelerated with this technique is still not comparable with that of conventional accelerators (large energy spread, low repetition rate, and large emittance); radiofrequency-based accelerators, in fact, are limited in accelerating field (10-100 MV/m) requiring therefore hundred of meters of distances to reach the GeV energies, but can provide very bright electron bunches. To combine high brightness electron bunches from conventional accelerators and high accelerating fields reachable with plasmas could be a good compromise allowing to further accelerate high brightness electron bunches coming from LINAC while preserving electron beam quality. Following the idea of plasma wave resonant excitation driven by a train of short bunches, we have started to study the requirements in terms of plasma for SPARC_LAB (Ferrario et al., 2013 [1]). In particular here we focus on hydrogen plasma discharge, and in particular on the theoretical and numerical estimates of the ionization process which are very useful to design the discharge circuit and to evaluate the current needed to be supplied to the gas in order to have full ionization. Eventually, the current supplied to the gas simulated will be compared to that measured experimentally.
Plasma production for electron acceleration by resonant plasma wave
Anania, M.P., E-mail: maria.pia.anania@lnf.infn.it [INFN - LNF, via Enrico Fermi, 40, 00044 Frascati (Italy); Biagioni, A.; Chiadroni, E. [INFN - LNF, via Enrico Fermi, 40, 00044 Frascati (Italy); Cianchi, A. [University of Rome Tor Vergata - INFN, via della Ricerca Scientifica, 1, 00133 Roma (Italy); INFN, Via della Ricerca Scientifica, 1, 00133 Roma (Italy); Croia, M.; Curcio, A. [INFN - LNF, via Enrico Fermi, 40, 00044 Frascati (Italy); University of Rome La Sapienza, Piazzale Aldo Moro, 2, 00185 Roma (Italy); Di Giovenale, D.; Di Pirro, G.P. [INFN - LNF, via Enrico Fermi, 40, 00044 Frascati (Italy); Filippi, F. [University of Rome La Sapienza, Piazzale Aldo Moro, 2, 00185 Roma (Italy); Ghigo, A.; Lollo, V.; Pella, S.; Pompili, R. [INFN - LNF, via Enrico Fermi, 40, 00044 Frascati (Italy); Romeo, S. [INFN - LNF, via Enrico Fermi, 40, 00044 Frascati (Italy); University of Rome La Sapienza, Piazzale Aldo Moro, 2, 00185 Roma (Italy); Ferrario, M. [INFN - LNF, via Enrico Fermi, 40, 00044 Frascati (Italy)
2016-09-01
Plasma wakefield acceleration is the most promising acceleration technique known nowadays, able to provide very high accelerating fields (10–100 GV/m), enabling acceleration of electrons to GeV energy in few centimeter. However, the quality of the electron bunches accelerated with this technique is still not comparable with that of conventional accelerators (large energy spread, low repetition rate, and large emittance); radiofrequency-based accelerators, in fact, are limited in accelerating field (10–100 MV/m) requiring therefore hundred of meters of distances to reach the GeV energies, but can provide very bright electron bunches. To combine high brightness electron bunches from conventional accelerators and high accelerating fields reachable with plasmas could be a good compromise allowing to further accelerate high brightness electron bunches coming from LINAC while preserving electron beam quality. Following the idea of plasma wave resonant excitation driven by a train of short bunches, we have started to study the requirements in terms of plasma for SPARC-LAB (Ferrario et al., 2013 [1]). In particular here we focus on hydrogen plasma discharge, and in particular on the theoretical and numerical estimates of the ionization process which are very useful to design the discharge circuit and to evaluate the current needed to be supplied to the gas in order to have full ionization. Eventually, the current supplied to the gas simulated will be compared to that measured experimentally.
Low Frequency Turbulence as the Source of High Frequency Waves in Multi-Component Space Plasmas
Khazanov, George V.; Krivorutsky, Emmanuel N.; Uritsky, Vadim M.
2011-01-01
Space plasmas support a wide variety of waves, and wave-particle interactions as well as wavewave interactions are of crucial importance to magnetospheric and ionospheric plasma behavior. High frequency wave turbulence generation by the low frequency (LF) turbulence is restricted by two interconnected requirements: the turbulence should be strong enough and/or the coherent wave trains should have the appropriate length. These requirements are strongly relaxed in the multi-component plasmas, due to the heavy ions large drift velocity in the field of LF wave. The excitation of lower hybrid waves (LHWs), in particular, is a widely discussed mechanism of interaction between plasma species in space and is one of the unresolved questions of magnetospheric multi-ion plasmas. It is demonstrated that large-amplitude Alfven waves, in particular those associated with LF turbulence, may generate LHW s in the auroral zone and ring current region and in some cases (particularly in the inner magnetosphere) this serves as the Alfven wave saturation mechanism. We also argue that the described scenario can playa vital role in various parts of the outer magnetosphere featuring strong LF turbulence accompanied by LHW activity. Using the data from THEMIS spacecraft, we validate the conditions for such cross-scale coupling in the near-Earth "flow-braking" magnetotail region during the passage of sharp injection/dipolarization fronts, as well as in the turbulent outflow region of the midtail reconnection site.
Wang, Z. B.; Nie, Q. Y.; Li, B. W.; Kong, F. R.
2017-01-01
Sub-atmospheric pressure plasma slabs exhibit the feature of relatively high plasma number density and high collisional frequency between electrons and neutral gases, as well as similar thickness to the electromagnetic (EM) wavelength in communication bands. The propagation characteristics of EM waves in sub-atmospheric pressure plasma slabs are attracting much attention of the researchers due to their applications in the plasma antenna, the blackout effect during reentry, wave energy injection in the plasma, etc. In this paper, a numerical model with a one-dimensional assumption has been established and therefore, it is used for the investigations of the propagation characteristics of the EM waves in plasma slabs. In this model, the EM waves propagating in both sub-wavelength plasma slabs and plasmas with thicker slabs can be studied simultaneously, which is superior to the model with geometrical optics approximation. The influence of EM wave frequencies and collisional frequencies on the amplitude of the transmitted EM waves is discussed in typical plasma profiles. The results will be significant for deep understanding of the propagation behaviors of the EM waves in sub-atmospheric pressure nonuniform plasma slabs, as well as the applications of the interactions between EM waves and the sub-atmospheric pressure plasmas.
Bottrill, K R H; Hesketh, G; Parmigiani, F; Richardson, D J; Petropoulos, P
2016-02-08
Adopting an exact solution to four-wave mixing (FWM), wherein harmonic evolution is described by the sum of two Bessel functions, we identify two causes of amplitude to phase noise conversion which impair FWM saturation based amplitude regenerators: self-phase modulation (SPM) and Bessel-order mixing (BOM). By increasing the pump to signal power ratio, we may arbitrarily reduce their impact, realising a phase preserving amplitude regenerator. We demonstrate the technique by applying it to the regeneration of a 10 GBaud QPSK signal, achieving a high level of amplitude squeezing with minimal amplitude to phase noise conversion.
Jian Cai
2016-12-01
Full Text Available The results of Lamb wave identification for the aerospace structures could be easily affected by the nonlinear-dispersion characteristics. In this paper, dispersion compensation of Lamb waves is of particular concern. Compared with the similar research works on the traditional signal domain transform methods, this study is based on signal construction from the viewpoint of nonlinear wavenumber linearization. Two compensation methods of linearly-dispersive signal construction (LDSC and non-dispersive signal construction (NDSC are proposed. Furthermore, to improve the compensation effect, the influence of the signal construction process on the other crucial signal properties, including the signal waveform and amplitude spectrum, is considered during the investigation. The linear-dispersion and non-dispersion effects are firstly analyzed. Then, after the basic signal construction principle is explored, the numerical realization of LDSC and NDSC is discussed, in which the signal waveform and amplitude spectrum preservation is especially regarded. Subsequently, associated with the delay-and-sum algorithm, LDSC or NDSC is employed for high spatial resolution damage imaging, so that the adjacent multi-damage or quantitative imaging capacity of Lamb waves can be strengthened. To verify the proposed signal construction and damage imaging methods, the experimental and numerical validation is finally arranged on the aluminum plates.
Cai, Jian; Yuan, Shenfang; Wang, Tongguang
2016-12-23
The results of Lamb wave identification for the aerospace structures could be easily affected by the nonlinear-dispersion characteristics. In this paper, dispersion compensation of Lamb waves is of particular concern. Compared with the similar research works on the traditional signal domain transform methods, this study is based on signal construction from the viewpoint of nonlinear wavenumber linearization. Two compensation methods of linearly-dispersive signal construction (LDSC) and non-dispersive signal construction (NDSC) are proposed. Furthermore, to improve the compensation effect, the influence of the signal construction process on the other crucial signal properties, including the signal waveform and amplitude spectrum, is considered during the investigation. The linear-dispersion and non-dispersion effects are firstly analyzed. Then, after the basic signal construction principle is explored, the numerical realization of LDSC and NDSC is discussed, in which the signal waveform and amplitude spectrum preservation is especially regarded. Subsequently, associated with the delay-and-sum algorithm, LDSC or NDSC is employed for high spatial resolution damage imaging, so that the adjacent multi-damage or quantitative imaging capacity of Lamb waves can be strengthened. To verify the proposed signal construction and damage imaging methods, the experimental and numerical validation is finally arranged on the aluminum plates.
Remarks on the parallel propagation of small-amplitude dispersive Alfvénic waves
S. Champeaux
1999-01-01
Full Text Available The envelope formalism for the description of a small-amplitude parallel-propagating Alfvén wave train is tested against direct numerical simulations of the Hall-MHD equations in one space dimension where kinetic effects are neglected. It turns out that the magnetosonic-wave dynamics departs from the adiabatic approximation not only near the resonance between the speed of sound and the Alfvén wave group velocity, but also when the speed of sound lies between the group and phase velocities of the Alfvén wave. The modulational instability then does not anymore affect asymptotically large scales and strong nonlinear effects can develop even in the absence of the decay instability. When the Hall-MHD equations are considered in the long-wavelength limit, the weakly nonlinear dynamics is accurately reproduced by the derivative nonlinear Schrödinger equation on the expected time scale, provided no decay instabilities are present. The stronger nonlinear regime which develops at later time is captured by including the coupling to the nonlinear dynamics of the magnetosonic waves.
Nonlinear Electromagnetic Waves and Spherical Arc-Polarized Waves in Space Plasmas
Tsurutani, B.; Ho, Christian M.; Arballo, John K.; Lakhina, Gurbax S.; Glassmeier, Karl-Heinz; Neubauer, Fritz M.
1997-01-01
We review observations of nonlinear plasma waves detected by interplanetary spacecraft. For this paper we will focus primarily on the phase-steepened properties of such waves. Plasma waves at comet Giacobini-Zinner measured by the International Cometary Explorer (ICE), at comets Halley and Grigg-Skjellerup measured by Giotto, and interplanetary Alfven waves measured by Ulysses, will be discussed and intercompared.
Gravitational waves in a free isotropic plasma. II
Galtsov, D.V.; Grats, IU.V.; Melkumova, E.IU.
1985-07-01
The generation of gravitational waves in an isotropic homogeneous plasma is investigated theoretically, within the frame work of a recently developed formalism. The effectiveness of different mechanisms generating gravitational waves is considered. Attention is given to thermal gravitational radiation by a two-component plasma; the transformation of longitudinal plasma waves into gravitons due to current fluctuations; and the generation of gravitational waves due to Langmuir turbulence. It is shown that collective plasma effects play a critical role in the generation of gravitational waves.
Sanders, A P; Joines, W T; Allis, J W
1985-01-01
A comparison of the effects of continuous-wave, sinusoidal-amplitude-modulated, and pulsed square-wave-modulated 591-MHz microwave exposures on brain energy metabolism was made in male Sprague-Dawley rats (175-225 g). Brain NADH fluorescence, adenosine triphosphate (ATP) concentration, and creatine phosphate (CP) concentration were determined as a function of modulation frequency. Brain temperatures of animals were maintained between -0.1 and -0.4 degrees C from the preexposure temperature when subjected to as much as 20 mW/cm2 (average power) CW, pulsed, or sinusoidal-amplitude modulated 591-MHz radiation for 5 min. Sinusoidal-amplitude-modulated exposures at 16-24 Hz showed a trend toward preferential modulation frequency response in inducing an increase in brain NADH fluorescence. The pulse-modulated and sinusoidal-amplitude-modulated (16 Hz) microwaves were not significantly different from CW exposures in inducing increased brain NADH fluorescence and decreased ATP and CP concentrations. When the pulse-modulation frequency was decreased from 500 to 250 pulses per second the average incident power density threshold for inducing an increase in brain NADH fluorescence increased by a factor of 4--ie, from about 0.45 to about 1.85 mW/cm2. Since brain temperature did not increase, the microwave-induced increase in brain NADH and decrease in ATP and CP concentrations was not due to hyperthermia. This suggests a direct interaction mechanism and is consistent with the hypothesis of microwave inhibition of mitochondrial electron transport chain function of ATP production.
Ion-acoustic cnoidal waves in plasmas with warm ions and kappa distributed electrons and positrons
Kaladze, T. [Department of Physics, Government College University (GCU), Lahore 54000 (Pakistan); I.Vekua Institute of Applied Mathematics, Tbilisi State University, 0186 Georgia (United States); Mahmood, S., E-mail: shahzadm100@gmail.com [Theoretical Physics Division (TPD), PINSTECH P.O. Nilore Islamabad 44000 (Pakistan); National Center for Physics (NCP), Quaid-i-Azam University Campus, Shahdra Valley Road, Islamabad 44000 (Pakistan)
2014-03-15
Electrostatic ion-acoustic periodic (cnoidal) waves and solitons in unmagnetized electron-positron-ion (EPI) plasmas with warm ions and kappa distributed electrons and positrons are investigated. Using the reductive perturbation method, the Korteweg-de Vries (KdV) equation is derived with appropriate boundary conditions for periodic waves. The corresponding analytical and various numerical solutions are presented with Sagdeev potential approach. Differences between the results caused by the kappa and Maxwell distributions are emphasized. It is revealed that only hump (compressive) structures of the cnoidal waves and solitons are formed. It is shown that amplitudes of the cnoidal waves and solitons are reduced in an EPI plasma case in comparison with the ordinary electron-ion plasmas. The effects caused by the temperature variations of the warm ions are also discussed. It is obtained that the amplitude of the cnoidal waves and solitons decreases for a kappa distributed (nonthermal) electrons and positrons plasma case in comparison with the Maxwellian distributed (thermal) electrons and positrons EPI plasmas. The existence of kappa distributed particles leads to decreasing of ion-acoustic frequency up to thermal ions frequency.
Ion-acoustic cnoidal waves in plasmas with warm ions and kappa distributed electrons and positrons
Kaladze, T.; Mahmood, S.
2014-03-01
Electrostatic ion-acoustic periodic (cnoidal) waves and solitons in unmagnetized electron-positron-ion (EPI) plasmas with warm ions and kappa distributed electrons and positrons are investigated. Using the reductive perturbation method, the Korteweg-de Vries (KdV) equation is derived with appropriate boundary conditions for periodic waves. The corresponding analytical and various numerical solutions are presented with Sagdeev potential approach. Differences between the results caused by the kappa and Maxwell distributions are emphasized. It is revealed that only hump (compressive) structures of the cnoidal waves and solitons are formed. It is shown that amplitudes of the cnoidal waves and solitons are reduced in an EPI plasma case in comparison with the ordinary electron-ion plasmas. The effects caused by the temperature variations of the warm ions are also discussed. It is obtained that the amplitude of the cnoidal waves and solitons decreases for a kappa distributed (nonthermal) electrons and positrons plasma case in comparison with the Maxwellian distributed (thermal) electrons and positrons EPI plasmas. The existence of kappa distributed particles leads to decreasing of ion-acoustic frequency up to thermal ions frequency.
Model of the Dynamics of Plasma-Wave Channels in Magnetized Plasmas
Shirokov, E. A.; Chugunov, Yu. V.
2016-06-01
We analyze the dynamics of the plasma-wave channels excited in magnetized plasmas in the whistler frequency range. A linear theory of excitation of a plasma waveguide by an external source is developed using the quasistatic approximation. Self-consistent spatio-temporal distributions of the electric field of quasipotential waves and plasma density, which are solutions of the nonlinear nonstationary problem of the ionizing self-channeling of waves in plasmas are found on the basis of the linear theory.
Effective action approach to wave propagation in scalar QED plasmas
Shi, Yuan; Qin, Hong
2016-01-01
A relativistic quantum field theory with nontrivial background fields is developed and applied to study waves in plasmas. The effective action of the electromagnetic 4-potential is calculated ab initio from the standard action of scalar QED using path integrals. The resultant effective action is gauge invariant and contains nonlocal interactions, from which gauge bosons acquire masses without breaking the local gauge symmetry. To demonstrate how the general theory can be applied, we study a cold unmagnetized plasma and a cold uniformly magnetized plasma. Using these two examples, we show that all linear waves well-known in classical plasma physics can be recovered from relativistic quantum results when taking the classical limit. In the opposite limit, classical wave dispersion relations are modified substantially. In unmagnetized plasmas, longitudinal waves propagate with nonzero group velocities even when plasmas are cold. In magnetized plasmas, anharmonically spaced Bernstein waves persist even when plasma...
On the role of wave-particle interactions in the macroscopic dynamics of collisionless plasmas
Wilson, Lynn B; Osmane, Adnane; Malaspina, David M
2015-01-01
What is the relative importance of small-scale (i.e., electron to sub-electron scales), microphysical plasma processes to the acceleration of particles from thermal to suprathermal or even to cosmic-ray energies? Additionally, can these microphysical plasma processes influence or even dominate macroscopic (i.e., greater than ion scales) processes, thus affecting global dynamics? These are fundamental and unresolved questions in plasma and astrophysical research. Recent observations of large amplitude electromagnetic waves in the terrestrial radiation belts [i.e., Cattell et al., 2008; Kellogg et al., 2010; Wilson III et al., 2011] and in collisionless shock waves [i.e., Wilson III et al., 2014a,b] have raised questions regarding the macrophysical effect of these microscopic waves. The processes thought to dominate particle acceleration and the macroscopic dynamics in both regions have been brought into question with these recent observations. The relative importance of wave-particle interactions has recently ...
Planar dust-acoustic waves in electron-positron-ion-dust plasmas with dust size distribution
Wang, Hong-Yan; Zhang, Kai-Biao [Sichuan University of Science and Engineering, Zigong (China)
2014-06-15
Nonlinear dust-acoustic solitary waves which are described with a Kortweg-de vries (KdV) equation by using the reductive perturbation method, are investigated in a planar unmagnetized dusty plasma consisting of electrons, positrons, ions and negatively-charged dust particles of different sizes and masses. The effects of the power-law distribution of dust and other plasma parameters on the dust-acoustic solitary waves are studied. Numerical results show that the dust size distribution has a significant influence on the propagation properties of dust-acoustic solitons. The amplitudes of solitary waves in the case of a power-law distribution is observed to be smaller, but the soliton velocity and width are observed to be larger, than those of mono-sized dust grains with an average dust size. Our results indicate that only compressed solitary waves exist in dusty plasma with different dust species. The relevance of the present investigation to interstellar clouds is discussed.
Identifying seismic noise sources and their amplitude from P wave microseisms.
Neale, Jennifer; Harmon, Nicholas; Srokosz, Meric
2016-04-01
Understanding sources of seismic noise is important for a range of applications including seismic imagery, time-lapse, and climate studies. For locating sources from seismic data, body waves offer an advantage over surface waves because they can reveal the distance to the source as well as direction. Studies have found that body waves do originate from regions predicted by models (Obrebski et al., 2013), where wave interaction intensity and site effect combine to produce the source (Ardhuin & Herbers, 2013). Here, we undertake a quantitative comparison between observed body wave microseisms and modelled sources- in terms of location, amplitude, and spectral shape- with the aim of understanding how well sources are observed and potentially what they reveal about the underlying ocean wavefield. We used seismic stations from the Southern California Seismic Network, and computed beamformer output as a function of time, frequency, slowness and azimuth. During winter months (October - mid March) the dominant arrivals at frequencies 0.18-0.22 Hz were P waves that originated from the North Pacific, whilst arrivals from the North Atlantic dominated at slightly lower frequencies of 0.16-0.18 Hz. Based on this, we chose to focus on P waves during winter, and back-projected the beamformer energy onto a global grid using P wave travel timetables (following Gerstoft et al., 2008). We modelled the seismic sources using Wavewatch III and site effect coefficients calculated following Ardhuin and Herbers (2013). We output the beamformer and the modelled sources on a 2° global grid averaged over 6 hour periods from September 2012 to September 2014, at seismic frequencies of 0.06 to 0.3 Hz. We then integrated the spectra over the full frequency range. Here we focus on results from the first winter in the North Pacific. Preliminary results indicate that the logarithm of the modelled source and the logarithm of the beamformer output are well described by a two-term exponential model
Hafez, M. G.; Talukder, M. R.; Sakthivel, R.
2016-05-01
The theoretical and numerical studies have been investigated on nonlinear propagation of weakly relativistic ion acoustic solitary waves in an unmagnetized plasma system consisting of nonextensive electrons, positrons and relativistic thermal ions. To study the characteristics of nonlinear propagation of the three-component plasma system, the reductive perturbation technique has been applied to derive the Korteweg-de Vries equation, which divulges the soliton-like solitary wave solution. The ansatz method is employed to carry out the integration of this equation. The effects of nonextensive electrons, positrons and relativistic thermal ions on phase velocity, amplitude and width of soliton and electrostatic nonlinear propagation of weakly relativistic ion acoustic solitary waves have been discussed taking different plasma parameters into consideration. The obtained results can be useful in understanding the features of small amplitude localized relativistic ion acoustic solitary waves in an unmagnetized three-component plasma system for hard thermal photon production with relativistic heavy ions collision in quark-gluon plasma as well as for astrophysical plasmas.
Hafez, M. G.; Talukder, M. R.; Hossain Ali, M.
2017-04-01
The Burgers equation is obtained to study the characteristics of nonlinear propagation of ionacoustic shock, singular kink, and periodic waves in weakly relativistic plasmas containing relativistic thermal ions, nonextensive distributed electrons, Boltzmann distributed positrons, and kinematic viscosity of ions using the well-known reductive perturbation technique. This equation is solved by employing the ( G'/ G)-expansion method taking unperturbed positron-to-electron concentration ratio, electron-to-positron temperature ratio, strength of electrons nonextensivity, ion kinematic viscosity, and weakly relativistic streaming factor. The influences of plasma parameters on nonlinear propagation of ion-acoustic shock, periodic, and singular kink waves are displayed graphically and the relevant physical explanations are described. It is found that these parameters extensively modify the shock structures excitation. The obtained results may be useful in understanding the features of small but finite amplitude localized relativistic ion-acoustic shock waves in an unmagnetized plasma system for some astrophysical compact objects and space plasmas.
Nonlinear features of ion acoustic shock waves in dissipative magnetized dusty plasma
Sahu, Biswajit; Sinha, Anjana; Roychoudhury, Rajkumar
2014-10-01
The nonlinear propagation of small as well as arbitrary amplitude shocks is investigated in a magnetized dusty plasma consisting of inertia-less Boltzmann distributed electrons, inertial viscous cold ions, and stationary dust grains without dust-charge fluctuations. The effects of dissipation due to viscosity of ions and external magnetic field, on the properties of ion acoustic shock structure, are investigated. It is found that for small amplitude waves, the Korteweg-de Vries-Burgers (KdVB) equation, derived using Reductive Perturbation Method, gives a qualitative behaviour of the transition from oscillatory wave to shock structure. The exact numerical solution for arbitrary amplitude wave differs somehow in the details from the results obtained from KdVB equation. However, the qualitative nature of the two solutions is similar in the sense that a gradual transition from KdV oscillation to shock structure is observed with the increase of the dissipative parameter.
Nonlinear features of ion acoustic shock waves in dissipative magnetized dusty plasma
Sahu, Biswajit, E-mail: biswajit-sahu@yahoo.co.in [Department of Mathematics, West Bengal State University, Barasat, Kolkata 700126 (India); Sinha, Anjana, E-mail: sinha.anjana@gmail.com [Department of Instrumentation Science, Jadavpur University, Kolkata 700032 (India); Roychoudhury, Rajkumar, E-mail: rroychoudhury123@gmail.com [Department of Mathematics, Visva-Bharati, Santiniketan 731204, India and Advanced Centre for Nonlinear and Complex Phenomena, 1175 Survey Park, Kolkata 700075 (India)
2014-10-15
The nonlinear propagation of small as well as arbitrary amplitude shocks is investigated in a magnetized dusty plasma consisting of inertia-less Boltzmann distributed electrons, inertial viscous cold ions, and stationary dust grains without dust-charge fluctuations. The effects of dissipation due to viscosity of ions and external magnetic field, on the properties of ion acoustic shock structure, are investigated. It is found that for small amplitude waves, the Korteweg-de Vries-Burgers (KdVB) equation, derived using Reductive Perturbation Method, gives a qualitative behaviour of the transition from oscillatory wave to shock structure. The exact numerical solution for arbitrary amplitude wave differs somehow in the details from the results obtained from KdVB equation. However, the qualitative nature of the two solutions is similar in the sense that a gradual transition from KdV oscillation to shock structure is observed with the increase of the dissipative parameter.
Development of Small Plasma Wave Receiver with a Dedicated Chip for Scientific Spacecraft
Fukuhara, H.; Kojima, H.; Ishii, H.; Okada, S.; Yamakawa, H.
2012-04-01
Since space is filled with collisionless plasmas, kinetic energy of each particle of the plasmas is exchanged via electric and magnetic fields, so-called plasma waves. The plasma waves have been observed a number of scientific spacecraft. Plasma wave receivers are classified into two kinds of the receiver, spectrum receivers, and waveform receivers. The spectrum receivers provide an overview of the plasma waves. The waveform receivers give not only amplitude but also phase of the plasma waves. Phase information between the plasma waves and plasma particle is essential in wave-particle interactions. It is important for understanding physical processes to combine both kinds of data of spectra and waveforms. Since the plasma waves have various intensities in wide-band frequency range, from DC to tens of MHz, the onboard instruments for the plasma wave observation are required to have low noise, high sensitivity, and wide dynamic range in wide-band. The required performances lead to increase the weight budget of the analog part of the instrument. The dedicated system chip can drastically decrease weight budget of the plasma wave instruments for multi-point observation missions and deep space exploration missions. It is also significant that manufacturing a number of instruments with the same performance becomes easy. In this paper, we demonstrate the miniaturized plasma wave receiver, which is realized in a dedicated chip for the analog part. The spectrum receiver is a double super heterodyne receiver, so-called `Sweep Frequency Analyzer (SFA).' This SFA is improved in the time resolution with keeping good frequency resolution by combining the analog frequency conversion and FFT. The SFA consists of an amplifier, a frequency synthesizer, mixers and band-pass filters. These component circuits are fabricated in chips and their performances are tested. The waveform receiver generally consists of the band-limiting filter, the amplifier, the anti-aliasing filter, and the A
Spin waves and spin instabilities in quantum plasmas
Andreev, P A
2014-01-01
We describe main ideas of method of many-particle quantum hydrodynamics allows to derive equations for description of quantum plasma evolution. We also present definitions of collective quantum variables suitable for quantum plasmas. We show that evolution of magnetic moments (spins) in quantum plasmas leads to several new branches of wave dispersion: spin-electromagnetic plasma waves and self-consistent spin waves. Propagation of neutron beams through quantum plasmas is also considered. Instabilities appearing due to interaction of magnetic moments of neutrons with plasma are described.
Heritability of Tpeak-Tend Interval and T-wave Amplitude: A Twin Study
Haarmark, Christian; Kyvik, Kirsten O; Vedel-Larsen, Esben;
2011-01-01
BACKGROUND: -Tpeak-Tend interval (TpTe) and T-wave amplitude (Tamp) carry diagnostic and prognostic information regarding cardiac morbidity and mortality. Heart rate and QT interval are known to be heritable traits. The heritability of T-wave morphology parameters such as TpTe and Tamp is unknown....... TpTe and Tamp were evaluated in a large sample of twins. METHODS AND RESULTS: -Twins from the GEMINAKAR study (611 pairs, 246 monozygotic, 365 dizygotic, aged 38±11 years, 49 % men) who had an ECG performed during 1997-2000 were included. Tamp was measured in leads V1 and V5. Duration variables (RR...... are heritable ECG parameters....
Numerical studies of large-amplitude internal waves shoaling and breaking at shelf slopes
Thiem, Øyvind; Berntsen, Jarle
2009-12-01
Hydro carbon fields beyond the shelf break are presently being explored and developed, which has increased the scientific focus in this area. Measurements from the slopes reveal large variability in temperature and velocity, and some of the observed events are due to interactions between large-amplitude oscillations of the thermocline and the topography. The present study focuses on the strong currents that are generated near the seabed during shoaling and breaking of internal waves along shelf slopes. The parameter regime used is similar to the one for the Nordic Seas. The results show that, during shoaling of large internal waves along (gentle) slopes, the energy is transferred towards smaller scales and strong velocities (over 1 m s - 1) can be generated. To resolve all scales involved is still not feasible, and therefore, the model results are sensitive to the grid size and the subgrid scale closure.
A unitarity analysis on the I=2 $d$ wave $\\pi\\pi$ scattering amplitude
Wang, J; Zheng, H Q; Wang, Jian-jun
2005-01-01
We study $d$ wave $\\pi\\pi$ scattering phase shift using a proper unitarization approach. It is verified that the $f_2(1270)$ resonance corresponds to a twin pole structure: one on the second sheet, another one on the third sheet. Also we find fair agreement on $f_2(1270)$ pole's mass and width between our results and the PDG values. Besides, our analysis reveals the existence of a virtual state in this channel. Its pole location is determined by fitting experimental data and it is found to be in good agreement with the prediction from chiral perturbation theory. Our analysis demonstrates that partial wave amplitudes calculated in chiral perturbation theory are reliable in the small $|s|$ region, contrary to some unitarization models.
Plasma Waves and Jets from Moving Conductors
Gralla, Samuel E
2016-01-01
We consider force-free plasma waves launched by the motion of conducting material through a magnetic field. We develop a spacetime-covariant formalism for perturbations of a uniform magnetic field and show how the transverse motion of a conducting fluid acts as a source. We show that fast-mode waves are sourced by the compressibility of the fluid, with incompressible fluids launching a pure-Alfven outflow. Remarkably, this outflow can be written down in closed form, at the nonlinear level, for an arbitrary incompressible flow. The instantaneous flow velocity is imprinted on the magnetic field and transmitted away at the speed of light, carrying detailed information about the conducting source at the time of emission. These results can be applied to transients in pulsar outflows and to jets from neutron stars orbiting in the magnetosphere of another compact object. We discuss jets from moving conductors in some detail.
Lu, Ding; Xie, Bai-Song
2013-01-01
Effects of ion mobility and positron fraction on solitary waves of envelop of laser field and potential of electrostatic field in weak relativistic electron-positron-ion plasma are investigated. The parameter region for the existence of solitary waves is obtained analytically, and the reasonable choice of parameters is clarified. Both cases of mobile and immobile ions are considered. It is found that the amplitudes of solitary waves in the former case are larger compared to the latter case. For small plasma density, the localized solitary wave solutions in terms of approximate perturbation analytical method are consistent well with that by exact numerical calculations. However as the plasma density increases the analytical method loses its validity more and more. The influence of the positron fraction on the amplitudes of solitary waves shows a monotonous increasing relation. Implication of our results to the particle acceleration is also discussed briefly.
Lu, Ding; Li, Zi-Liang; Xie, Bai-Song
2013-09-01
The effects of ion mobility and positron fraction on the solitary waves of the laser field envelope and the potential of the electrostatic field in weak relativistic electron-positron-ion plasma are investigated. The parameter region for the existence of solitary waves is obtained analytically, and a reasonable choice of parameters is clarified. Both cases of mobile and immobile ions are considered. It is found that the amplitudes of solitary waves in the former case are larger compared to the latter case. For small plasma density, the localized solitary wave solutions in terms of the approximate perturbation analytical method are very consistent with those by exact numerical calculations. However, as the plasma density increases the analytical method loses its validity more and more. The influence of the positron fraction on the amplitudes of solitary waves shows a monotonous increasing relation. The implications of our results to particle acceleration are also discussed briefly.
Radiation Heat Waves in Gold Plasma
YANG Jia-Min; XU Yan; DING Yao-Nan; LAI Dong-Xian; DING Yong-Kun; JIANG Shao-En; ZHENG Zhi-Jian; MIAO Wen-Yong
2003-01-01
Eight beams 0.35/um laser with pulse duration of about 1.0ns and energy of 260 J per beam was injected into a cylindrical cavity to generate intense x-ray radiation on the "Shengguang I" high power laser facility. Gold foils with a thickness in the range of 0.09-0.52/j,m were attached on the diagnostic hole of the cavity and ablated by the intense x-ray radiation. The propagating radiation heat wave in the high-Z gold plasma was observed clearly. For comparison, we also simulated the experimental results.
Stimulated emission of fast Alfv\\'en waves within magnetically confined fusion plasmas
Cook, J W S; Chapman, S C
2016-01-01
A fast Alfv\\'en wave with finite amplitude is shown to grow by a stimulated emission process that we propose for exploitation in toroidal magnetically confined fusion plasmas. Stimulated emission occurs while the wave propagates inward through the outer mid-plane plasma, where a population inversion of the energy distribution of fusion-born ions is observed to arise naturally. Fully nonlinear first principles simulations, which self-consistently evolve particles and fields under the Maxwell-Lorentz system, demonstrate this novel "alpha-particle channelling" scenario for the first time.
Stimulated Emission of Fast Alfvén Waves within Magnetically Confined Fusion Plasmas
Cook, J. W. S.; Dendy, R. O.; Chapman, S. C.
2017-05-01
A fast Alfvén wave with a finite amplitude is shown to grow by a stimulated emission process that we propose for exploitation in toroidal magnetically confined fusion plasmas. Stimulated emission occurs while the wave propagates inward through the outer midplane plasma, where a population inversion of the energy distribution of fusion-born ions is observed to arise naturally. Fully nonlinear first-principles simulations, which self-consistently evolve particles and fields under the Maxwell-Lorentz system, demonstrate this novel "α -particle channeling" scenario for the first time.
A small-amplitude study of solitons near critical plasma compositions
Olivier, Carel P.; Verheest, Frank; Maharaj, Shimul K.
2016-12-01
The properties of small-amplitude solitons are established near critical plasma compositions in a generalized fluid plasma with an arbitrary number of species. The study is conducted via a Taylor series expansion of the Sagdeev potential. It is shown that there are two types of critical compositions, namely rich critical and poor critical compositions. The coexistence of positive and negative polarity solitons is shown to arise at rich critical compositions and near rich critical compositions. At poor critical compositions, no small-amplitude solitons exist, while weak double layers arise near poor critical compositions. A novel analytical expression is obtained for a small-amplitude acoustic speed soliton solution near rich critical compositions. These solitons have a Lorentzian shape with much fatter tails than regular solitons. A case study is also performed for a simple fluid model consisting of cold ions and two Boltzmann electron species. Exact agreement is obtained between the Sagdeev analysis and reductive perturbation theory. For the first time, we derive the same Lorentzian acoustic speed soliton from reductive perturbation theory.
M Singh; P N Deka
2006-03-01
A theoretical study is made on the generation mechanism of ion acoustics wave in the presence of lower hybrid wave turbulence field in inhomogeneous plasma on the basis of plasma-maser interaction. The lower hybrid wave turbulence field is taken as the low-frequency turbulence field. The growth rate of test high frequency ion acoustics wave is obtained with the involvement of spatial density gradient parameter. A comparative study of the role of density gradient for the generation of ion acoustics wave on the basis of plasma-maser effect is presented. It is found that the density gradient influences the growth rate of ion acoustics wave.
Probing phase of a scattering amplitude beyond the plane-wave approximation
Karlovets, Dmitry V
2016-01-01
Within a plane-wave approach, a number of scattering events in a generic collision process is insensitive to an overall complex phase of a transition amplitude, although this phase is extremely important for a number of problems, especially in hadronic physics at the LHC energies. In reality, however, the particles are better described as localized wave packets with the mean momenta $p$, their uncertainties $\\sigma$, and here we show that the observables grow dependent upon this phase if one lays aside the simplified plane-wave model. A relative contribution of the phase to the cross section is generally attenuated by a small factor $\\sigma^2/p^2 \\ll 1$, making its experimental measurement a rather challenging task. We discuss two methods for probing how this phase changes with the transferred momentum $t$, either by colliding two beams at a non-zero impact-parameter (say, $pp \\rightarrow X$) or by employing the states with the non-trivial wave functions, for instance, vortex particles carrying orbital angula...
Nonlinear Alfvén wave propagating in ideal MHD plasmas
Zheng, Jugao; Chen, Yinhua; Yu, Mingyang
2016-01-01
The behavior of nonlinear Alfvén waves propagating in ideal MHD plasmas is investigated numerically. It is found that in a one-dimensional weakly nonlinear system an Alfvén wave train can excite two longitudinal disturbances, namely an acoustic wave and a ponderomotively driven disturbance, which behave differently for β \\gt 1 and β \\lt 1, where β is the ratio of plasma-to-magnetic pressures. In a strongly nonlinear system, the Alfvén wave train is modulated and can steepen to form shocks, leading to significant dissipation due to appearance of current sheets at magnetic-pressure minima. For periodic boundary condition, we find that the Alfvén wave transfers its energy to the plasma and heats it during the shock formation. In two-dimensional systems, fast magneto-acoustic wave generation due to Alfvén wave phase mixing is considered. It is found that the process depends on the amplitude and frequency of the Alfvén waves, as well as their speed gradients and the pressure of the background plasma.
Crawford, J D
1994-01-01
An amplitude equation for an unstable mode in a collisionless plasma is derived from the dynamics on the unstable manifold of the equilibrium F_0(v).\\\\ The mode eigenvalue arises from a simple zero of the dielectric \\epsilon_{{k}}(z); as the linear growth rate \\gamma vanishes, the eigenvalue merges with the continuous spectrum on the imaginary axis and disappears. The evolution of the mode amplitude \\rho(t) is studied using an expansion in \\rho. As \\glim, the expansion coefficients diverge, but these singularities are absorbed by rescaling the amplitude: \\rho(t)\\equiv\\gamma^2\\,r(\\gamma t). This renders the theory finite and also indicates that the electric field exhibits trapping scaling E\\sim\\gamma^2. These singularities and scalings are independent of the specific F_0(v) considered. The asymptotic dynamics of r(\\tau) depends on F_0 only through \\exp{i\\xi} where d\\epsilon_{{k}} /dz=|{\\epsilon'_{{k}}}|\\exp{-i\\xi/2}. Similar results also hold for the electric field and distribution function.
Body wave travel times and amplitudes for present-day seismic model of Mars
Raevskiy, Sergey; Gudkova, Tamara
At the moment Martian interior structure models are constrained by the satellite observational data (the mass, the moment of inertia factor, the Love number k _{2}) (Konopliv et al., 2011) and high pressure experimental data (Bertka and Fei, 1997). Seismological observations could provide unparalleled capability for studying Martian interiors. Future missions include seismic experiments on Mars (Lognonné et al., 2012). The main instrument for these seismic experiments is a broadband seismometer (Robert et al., 2012). When seismic measurements are not yet available, physically consistent interior models, characterized by properties of relevant minerals, make possible to study of the seismic response of the planet. \\To estimate travel times for direct P, S, core reflected PcP, ScS and core refracted PKP body waves as a function of epicentral distance and hypocentral depth, as well as their amplitudes at the surface for a given marsquake, software product was developed in MatLab, as it encompasses many plotting routines that plot resulting travel times and ray paths. The computational results have been compared with the program TTBox (Knapmeyer, 2004). The code computes seismic ray paths and travel times for a one-dimentional spherical interior model (density and seismic velocities are functions of a radius only). Calculations of travel times tables for direct P, S, core reflected PcP, ScS and core refracted PKP waves and their amplitudes are carried out for a trial seismic model of Mars M14_3 from (Zharkov et al., 2009): the core radius is 1800 km, the thickness of the crust is 50 km. Direct and core reflected P and S waves are recorded to a maximum epicentral distance equal to about 100(°) , and PKP arrivals can be detected for epicental distances larger than 150(°) . The shadow zone is getting wider in comparison with previous results (Knapmeyer, 2010), as the liquid core radius of the seismic model under consideration is larger. Based on the estimates of
Magnetohydrodynamic waves in fusion and astrophysical plasmas.
Goedbloed, J. P.
Macroscopic plasma dynamics in both controlled thermonuclear confinement machines and in the atmospheres of X-ray emitting stars is described by the equations of magnetohydrodynamics. This provides a vast area of overlapping research activities which is presently actively pursued. In this lecture the author concentrates on some important differences in the dynamics of the two confined plasma systems related to the very different geometries that are encountered and, thus, the role of the different boundary conditions that have to be posed. As a result, the basic MHD waves in a tokamak are quite different from those found in a solar magnetic flux tube. The result is that, whereas the three well-known MHD waves can be traced stepwise in the curved geometry of a tokamak, their separate existence is eliminated right from the start in a line-tied coronal loop because line-tying in general conflicts with the phase relationships between the vector components of the three velocity fields. The consequences are far-reaching, viz. completely different resonant frequencies and continuous spectra, absence of rational magnetic surfaces, and irrelevance of local marginal stability theory for coronal magnetic loops.
Ion-acoustic solitons, double layers and rogue waves in plasma having superthermal electrons
Singh Saini, Nareshpal
2016-07-01
Most of the space and astrophysical plasmas contain different type of charged particles with non-Maxwellian velocity distributions (e.g., nonthermal, superthermal, Tsallis ). These distributions are commonly found in the auroral region of the Earth's magnetosphere, planetary magnetosphere, solar and stellar coronas, solar wind, etc. The observations from various satellite missions have confirmed the presence of superthermal particles in space and astrophysical environments. Over the last many years, there have been a much interest in studying the different kind of properties of the electrostatic nonlinear excitations (solitons, double layers, rogue waves etc.) in a multi-component plasmas in the presence of superthermal particles. It has been analyzed that superthermal distributions are more appropriate than Maxwellian distribution for the modeling of space data. It is interesting to study the dynamics of various kinds of solitary waves, Double layers, Shocks etc. in varieties of plasma systems containing different kind of species obeying Lorentzian (kappa-type)/Tsallis distribution. In this talk, I have focused on the study of large amplitude IA solitary structures (bipolar solitary structures, double layers etc.), modulational instability and rogue waves in multicomponent plasmas. The Sagdeev potential method has been employed to setup an energy balance equation, from which we have studied the characteristics of large amplitude solitary waves under the influence of superthermality of charged particles and other plasma parameters. The critical Mach number has been determined, above which solitary structures are observed and its variation with superthermality of electrons and other parameters has also been discussed. Double layers have also been discussed. Multiple scale reductive perturbation method has been employed to derive NLS equation. From the different kind of solutions of this equation, amplitude modulation of envelope solitons and rogue waves have been
Cattell, Cynthia; Breneman, A.; Goetz, K.; Kellogg, P.; Kersten, K.; Wygant, J.; Wilson, L. B., III; Looper, Mark D.; Blake, J. Bernard; Roth, I.
2012-01-01
One of the critical problems for understanding the dynamics of Earth's radiation belts is determining the physical processes that energize and scatter relativistic electrons. We review measurements from the Wind/Waves and STEREO S/Waves waveform capture instruments of large amplitude whistler-mode waves. These observations have provided strong evidence that large amplitude (100s mV/m) whistler-mode waves are common during magnetically active periods. The large amplitude whistlers have characteristics that are different from typical chorus. They are usually nondispersive and obliquely propagating, with a large longitudinal electric field and significant parallel electric field. We will also review comparisons of STEREO and Wind wave observations with SAMPEX observations of electron microbursts. Simulations show that the waves can result in energization by many MeV and/or scattering by large angles during a single wave packet encounter due to coherent, nonlinear processes including trapping. The experimental observations combined with simulations suggest that quasilinear theoretical models of electron energization and scattering via small-amplitude waves, with timescales of hours to days, may be inadequate for understanding radiation belt dynamics.
Reed, Evan J.; Armstrong, Michael R.
2010-09-07
Strain waves of THz frequencies can coherently generate radiation when they propagate past an interface between materials with different piezoelectric coefficients. Such radiation is of detectable amplitude and contains sufficient information to determine the time-dependence of the strain wave with unprecedented subpicosecond, nearly atomic time and space resolution.
Upconversion of whistler waves by gyrating ion beams in a plasma
Harsha Jalori; Sunil K Singh; A K Gwal
2004-09-01
A gyrating ion beam, with a ring-shaped distribution in velocity, supports negative energy beam modes near the harmonics of beam gyro-frequency. An investigation of the non-linear interaction of high-frequency whistler waves with the negative energy beam cyclotron mode is made. A non-linear dispersion relation is derived for the coupled modes. 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 side band of frequency lower than that of pump wave. In Case 2 a high-amplitude whistler wave decays into two lower frequency daughter waves, called the low-frequency mode and whistler waves. Generation mechanism of these waves has application in space and laboratory plasmas.
Chatterjee, Debjani; Misra, A P
2015-12-01
The nonlinear theory of amplitude modulation of electrostatic wave envelopes in a collisionless electron-positron (EP) pair plasma is studied by using a set of Vlasov-Poisson equations in the context of Tsallis' q-nonextensive statistics. In particular, the previous linear theory of Langmuir oscillations in EP plasmas [Saberian and Esfandyari-Kalejahi, Phys. Rev. E 87, 053112 (2013)] is rectified and modified. Applying the multiple scale technique (MST), it is shown that the evolution of electrostatic wave envelopes is governed by a nonlinear Schrödinger (NLS) equation with a nonlocal nonlinear term ∝P∫|ϕ(ξ',τ)|(2)dξ'ϕ/(ξ-ξ') [where P denotes the Cauchy principal value, ϕ is the small-amplitude electrostatic (complex) potential, and ξ and τ are the stretched coordinates in MST], which appears due to the wave-particle resonance. It is found that a subregion 1/3Landau damping) due to the nonlocal nonlinearity in the NLS equation. Furthermore, the effect of the nonlinear Landau damping is to slow down the amplitude of the wave envelope, and the corresponding decay rate can be faster the larger is the number of superthermal particles in pair plasmas.
Magnetoacoustic waves in a partially ionized two-fluid plasma
Soler, Roberto; Ballester, Jose Luis
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 the 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 $\\beta$, 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 da...
Fundamental study on subharmonic imaging by irradiation of amplitude-modulated ultrasound waves.
Maikusa, Norihide; Fukami, Tadanori; Yuasa, Tetsuya; Tamura, Yasutaka; Akatsuka, Takao
2007-07-01
The second harmonic and subharmonic components, the frequencies of which are twice and one half the fundamental frequency, are included in echoes from contrast agents. An imaging method, which employs a second harmonic (second harmonic imaging), is widely used in medical diagnoses. On the other hand, subharmonic is expected to provide a higher contrast between biological tissues and blood flow because echo signals are generated only from blood containing the contrast agents. However, the subharmonic component echo signal power from contrast agents is relatively low. This has resulted in little progress in the field of subharmonic imaging. In this study, a new imaging method is proposed using amplitude-modulated waves as transmitted waves combined with the pulse inversion method to enhance subharmonic echo signals. Two optimal frequencies are set, including the modulated waves, F(1) and F(2), so that the subharmonic frequency of F(1) and the second harmonic frequency of F(2) may result in the same value. This allows a more powerful signal at the frequency band because the second harmonic and subharmonic components are integrated. Furthermore, a B-mode ultrasound image of an agar phantom that imitated biological tissue and showed the effectiveness of our method was reconstructed. As a result, the echo power of the subharmonic component was enhanced by approximately 11.8 dB more than the conventional method and the signal to noise ratio showed an improvement of 7.6 dB.
MIN Htwe, Y. M.
2016-12-01
Myanmar has suffered many times from earthquake disasters and four times from tsunamis according to historical data. The purpose of this study is to estimate the tsunami arrival time and maximum tsunami wave amplitude for the Rakhine coast of Myanmar using the TUNAMI F1 model. In this study I calculate the tsunami arrival time and maximum tsunami wave amplitude based on a tsunamigenic earthquake source of moment magnitude 8.5 in the Arakan subduction zone off the west-coast of Myanmar, using the TUNAMI F1 model, selecting eight points on Rakhine coast. The model result indicates that the tsunami waves would first hit Kyaukpyu on the Rakhine coast about 0.05 minutes after the onset of a magnitude 8.5 earthquake, and the maximum tsunami wave amplitude would be 2.37 meters.
Berger, R. L., E-mail: berger5@llnl.gov; Cohen, B. I. [Lawrence Livermore National Laboratory, University of California, P.O. Box 808, Livermore, California 94551 (United States); Brunner, S., E-mail: stephan.brunner@epfl.ch [Centre de Recherches en Physique des Plasmas, Association Euratom-Confédération Suisse, Ecole Polytechnique Fédérale de Lausanne, CRPP-PPB, CH-1015 Lausanne (Switzerland); Banks, J. W. [Department of Mathematical Sciences, Rensselaer Polytechnic Institute, AE 301, 110 8th Street, Troy, New York 12180 (United States); Winjum, B. J. [Department of Electrical Engineering, University of California, Los Angeles, California 90095 (United States)
2015-05-15
Kinetic simulations of two-dimensional finite-amplitude electron plasma waves are performed in a one-wavelength long system. A systematic study of the most unstable linear sideband mode, in particular its growth rate γ and wavenumber k{sub y}, is carried out by scanning the amplitude and wavenumber of the initial wave. Simulation results are compared with numerical and analytical solutions to a two-dimensional nonlinear Schrödinger model [H. A. Rose and L. Yin, Phys. Plasmas 15, 042311 (2008)] and to the reduced model by Kruer et al. [Phys. Rev. Lett. 23, 838 (1969)] generalized to two dimensions.
Nonlinear kinetic Alfvén waves with non-Maxwellian electron population in space plasmas
Masood, W.; Qureshi, M. N. S.; Yoon, P. H.; Shah, H. A.
2015-01-01
The present work discusses the effects of non-Maxwellian electron distributions on kinetic Alfvén waves in low-beta plasmas. Making use of the two-potential theory and employing the Sagdeev potential approach, the existence of solitary kinetic Alfvén waves having arbitrary amplitude is investigated. It is found that the use of non-Maxwellian population of electrons in the study of kinetic Alfvén waves leads to solutions corresponding to solitary structures that do not exist for Maxwellian electrons. The present investigation solves the riddle of plasma density fluctuations associated with strong electromagnetic perturbations observed by the Freja satellite. The present findings can also be applied to regions of space where various satellite missions have observed the presence of suprathermal populations of plasma species and where the low β assumption is valid.
Jain, S. L.; Tiwari, R. S.; Mishra, M. K.
2015-05-01
Large amplitude ion-acoustic solitons and double layers are studied using Sagdeev's pseudo potential technique in a collisionless unmagnetized plasma consisting of hot and cold Maxwellian electrons, warm adiabatic ions, and heavily charged massive dust grains. It is found that for the selected set of plasma parameters, the system can support both solitons and double layers in the presence of negative as well as positive dust in the plasma. Further we have also investigated the ranges of parameters for simultaneous existence of both rarefactive and compressive supersonic solitons. The effects of dust concentration and ion temperature on the amplitude and Mach number of the double layer have also been studied. Our findings may be helpful in understanding the formation of non-linear structures, specially the solitons and double layers in space plasma, such as: in interstellar clouds, circumstellar clouds, planetary rings, comets, cometary tails, asteroid zones, auroral plasma, magnetospheric plasma, pulsars, and other astronomical environments and laboratory plasmas.
Eide Per K
2011-02-01
Full Text Available Abstract Background In patients with idiopathic normal pressure hydrocephalus (iNPH responding to shunt surgery, we have consistently found elevated intracranial pressure (ICP wave amplitudes during diagnostic ICP monitoring prior to surgery. It remains unknown why ICP wave amplitudes are increased in these patients. Since iNPH is accompanied by a high incidence of vascular co-morbidity, a possible explanation is that there is reduced vascular compliance accompanied by elevated arterial blood pressure (ABP wave amplitudes and even altered cardiac output (CO. To investigate this possibility, the present study was undertaken to continuously monitor CO to determine if it is correlated to ABP and ICP wave amplitudes and the outcome of shunting in iNPH patients. It was specifically addressed whether the increased ICP wave amplitudes seen in iNPH shunt responders were accompanied by elevated CO and/or ABP wave amplitude levels. Methods Prospective iNPH patients (29 were clinically graded using an NPH grading scale. Continuous overnight minimally-invasive monitoring of CO and ABP was done simultaneously with ICP monitoring; the CO, ABP, and ICP parameters were parsed into 6-second time windows. Patients were assessed for shunt surgery on clinical grade, Evan's index, and ICP wave amplitude. Follow-up clinical grading was performed 12 months after surgery. Results ICP wave amplitudes but not CO or ABP wave amplitude, showed good correlation with the response to shunt treatment. The patients with high ICP wave amplitude did not have accompanying high levels of CO or ABP wave amplitude. Correlation analysis between CO and ICP wave amplitudes in individual patients showed different profiles [significantly positive in 10 (35% and significantly negative in 16 (55% of 29 recordings]. This depended on whether there was also a correlation between ABP and ICP wave amplitudes and on the average level of ICP wave amplitude. Conclusions These results gave no
Effect of electron inertia on dispersive properties of Alfvén waves in cold plasmas
Jana, Sayanee; Ghosh, Samiran; Chakrabarti, Nikhil
2017-10-01
The effect of electron inertia on Alfvén wave propagation is investigated in the framework of the two-fluid theory in a compressible magnetized plasma. The linear analysis of the governing equations manifests the dispersion relation of the circularly polarized Alfvén waves where the electron inertia is found to act as a source of dispersion. In the finite amplitude limit, the nonlinear Alfvén wave may be described by the Derivative Nonlinear Schrödinger equation (DNLSE) modified by third order dispersion arising due to finite electron inertia. The derived equation seems to be novel with respect to what exists in the literature of Alfvén wave dynamics. We have shown that this electron inertia modified DNLSE is completely integrable and an analytical solution is demonstrated with vanishing boundary conditions. The results are expected to be of special importance in the context of space and laboratory plasmas.
Large-amplitude internal waves sustain coral health during thermal stress
Schmidt, Gertraud M.; Wall, Marlene; Taylor, Marc; Jantzen, Carin; Richter, Claudio
2016-09-01
Ocean warming is a major threat for coral reefs causing widespread coral bleaching and mortality. Potential refugia are thus crucial for coral survival. Exposure to large-amplitude internal waves (LAIW) mitigated heat stress and ensured coral survival and recovery during and after an extreme heat anomaly. The physiological status of two common corals, Porites lutea and Pocillopora meandrina, was monitored in host and symbiont traits, in response to LAIW-exposure throughout the unprecedented 2010 heat anomaly in the Andaman Sea. LAIW-exposed corals of both species survived and recovered, while LAIW-sheltered corals suffered partial and total mortality in P. lutea and P. meandrina, respectively. LAIW are ubiquitous in the tropics and potentially generate coral refuge areas. As thermal stress to corals is expected to increase in a warming ocean, the mechanisms linking coral bleaching to ocean dynamics will be crucial to predict coral survival on a warming planet.
High latitude electromagnetic plasma wave emissions
Gurnett, D. A.
1983-01-01
The principal types of electromagnetic plasma wave emission produced in the high latitude auroral regions are reviewed. Three types of radiation are described: auroral kilometric radiation, auroral hiss, and Z mode radiation. Auroral kilometric radiation is a very intense radio emission generated in the free space R-X mode by electrons associated with the formation of discrete auroral arcs in the local evening. Theories suggest that this radiation is an electron cyclotron resonance instability driven by an enhanced loss cone in the auroral acceleration region at altitudes of about 1 to 2 R sub E. Auroral hiss is a somewhat weaker whistler mode emission generated by low energy (100 eV to 10 keV) auroral electrons. The auroral hiss usually has a V shaped frequency time spectrum caused by a freqency dependent beaming of the whistler mode into a conical beam directed upward or downward along the magnetic field.
2011-02-01
and experimental measurements were also made by Graw (1994), Stansberg, et al. (1996), Grue and Jensen (2006), Hennig, et al. (2006), and Clauss...Goda, Y. (1976), "On Wave Groups," Proc. 1st Intl. Conf. on the Behavior of Offshore Structures, Trondheim, Norway, pp. 1 15-128. Graw , K..-U. (1994
Effects of Schwarzschild Geometry on Isothermal Plasma Wave Dispersion
Sharif, M
2007-01-01
The behavior of isothermal plasma waves has been analyzed near the Schwarzschild horizon. We consider a non-rotating background with non-magnetized and magnetized plasmas. The general relativistic magnetohydrodynamical equations for the Schwarzschild planar analogue spacetime with an isothermal state of the plasma are formulated. The perturbed form of these equations is linearized and Fourier analyzed by introducing simple harmonic waves. The determinant of these equations in each case leads to a complex dispersion relation, which gives complex values of the wave number. This has been used to discuss the nature of the waves and their characteristics near the horizon.
Feng, Q S; Wang, Q; Zheng, C Y; Liu, Z J; Cao, L H; He, X T
2016-01-01
The properties of the nonlinear frequency shift (NFS) especially the fluid NFS from the harmonic generation of the ion-acoustic wave (IAW) in multi-ion species plasmas have been researched by Vlasov simulation. The pictures of the nonlinear frequency shift from harmonic generation and particles trapping are shown to explain the mechanism of NFS qualitatively. The theoretical model of the fluid NFS from harmonic generation in multi-ion species plasmas is given and the results of Vlasov simulation are consistent to the theoretical result of multi-ion species plasmas. When the wave number $k\\lambda_{De}$ is small, such as $k\\lambda_{De}=0.1$, the fluid NFS dominates in the total NFS and will reach as large as nearly $15\\%$ when the wave amplitude $|e\\phi/T_e|\\sim0.1$, which indicates that in the condition of small $k\\lambda_{De}$, the fluid NFS dominates in the saturation of stimulated Brillouin scattering especially when the nonlinear IAW amplitude is large.
Wave rectification in plasma sheaths surrounding electric field antennas
Boehm, M. H.; Carlson, C. W.; Mcfadden, J. P.; Clemmons, J. H.; Ergun, R. E.; Mozer, F. S.
1994-01-01
Combined measurements of Langmuir or broadband whistler wave intensity and lower-frequency electric field waveforms, all at 10-microsecond time resolution, were made on several recent sounding rockets in the auroral ionosphere. It is found that Langmuir and whistler waves are partically rectified in the plasma sheaths surrounding the payload and the spheres used as antennas. This sheath rectification occurs whenever the high frequency (HF) potential across the sheath becomes of the same order as the electron temperature or higher, for wave frequencies near or above the ion plasma frequency. This rectification can introduce false low-frequency waves into measurements of electric field spectra when strong high-frequency waves are present. Second harmonic signals are also generated, although at much lower levels. The effect occurs in many different plasma conditions, primarily producing false waves at frequencies that are low enough for the antenna coupling to the plasma to be resistive.
Time-domain hybrid method for simulating large amplitude motions of ships advancing in waves
Shukui Liu
2011-03-01
Full Text Available Typical results obtained by a newly developed, nonlinear time domain hybrid method for simulating large amplitude motions of ships advancing with constant forward speed in waves are presented. The method is hybrid in the way of combining a time-domain transient Green function method and a Rankine source method. The present approach employs a simple double integration algorithm with respect to time to simulate the free-surface boundary condition. During the simulation, the diffraction and radiation forces are computed by pressure integration over the mean wetted surface, whereas the incident wave and hydrostatic restoring forces/moments are calculated on the instantaneously wetted surface of the hull. Typical numerical results of application of the method to the seakeeping performance of a standard containership, namely the ITTC S175, are herein presented. Comparisons have been made between the results from the present method, the frequency domain 3D panel method (NEWDRIFT of NTUA-SDL and available experimental data and good agreement has been observed for all studied cases between the results of the present method and comparable other data.
Lo Martire, Viviana Carmen; Bastianini, Stefano; Berteotti, Chiara; Silvani, Alessandro; Zoccoli, Giovanna
2015-01-01
High amplitude theta wave bursts (HATs) were originally described during REMS and cataplexy in ORX-deficient mice as a novel neurophysiological correlate of narcolepsy (Bastianini et al., 2012). This finding was replicated the following year by Vassalli et al. in both ORX-deficient narcoleptic mice and narcoleptic children during cataplexy episodes (Vassalli et al., 2013). The relationship between HATs and narcolepsy-cataplexy in mice and patients indicates that the lack of ORX peptides is responsible for this abnormal EEG activity, the physiological meaning of which is still unknown. This review aimed to explore different phasic EEG events previously described in the published literature in order to find analogies and differences with HATs observed in narcoleptic mice and patients. We found similarities in terms of morphology, frequency and duration between HATs and several physiological (mu and wicket rhythms, sleep spindles, saw-tooth waves) or pathological (SWDs, HVSs, bursts of polyphasic complexes EEG complexes reported in a mouse model of CJD, and BSEs) EEG events. However, each of these events also shows significant differences from HATs, and thus cannot be equaled to them. The available evidence thus suggests that HATs are a novel neurophysiological phenomenon. Further investigations on HATs are required in order to investigate their physiological meaning, to individuate their brain structure(s) of origin, and to clarify the neural circuits involved in their manifestation.
Structure of the Particle-Hole Amplitudes in No-core Shell Model Wave Functions
Hayes, A C
2009-01-01
We study the structure of the no-core shell model wave functions for $^6$Li and $^{12}$C by investigating the ground state and first excited state electron scattering charge form factors. In both nuclei, large particle-hole ($ph$) amplitudes in the wave functions appear with the opposite sign to that needed to reproduce the shape of the $(e,e')$ form factors, the charge radii, and the B(E2) values for the lowest two states. The difference in sign appears to arise mainly from the monopole $\\Delta\\hbar\\omega=2$ matrix elements of the kinetic and potential energy (T+V) that transform under the harmonic oscillator SU(3) symmetries as $(\\lambda,\\mu)=(2,0)$. These are difficult to determine self-consistently, but they have a strong effect on the structure of the low-lying states and on the giant monopole and quadrupole resonances. The Lee-Suzuki transformation, used to account for the restricted nature of the space in terms of an effective interaction, introduces large higher-order $\\Delta\\hbar\\omega=n, n>$2, $ph$ ...
Dust acoustic shock wave generation due to dust charge variation in a dusty plasma
M R Gupta; S Sarkar; M Khan; Samiran Ghosh
2003-12-01
In a dusty plasma, the non-adiabaticity of the charge variation on a dust grain surface results in an anomalous dissipation. Analytical investigation shows that this results in a small but ﬁnite amplitude dust acoustic (DA) wave propagation which is described by the Korteweg–de Vries–Burger equation. Results of the numerical investigation of the propagation of large-amplitude dust acoustic stationary shock wave are presented here using the complete set of non-linear dust ﬂuid equations coupled with the dust charging equation and Poisson equation. The DA waves are of compressional type showing considerable increase of dust density, which is of signiﬁcant importance in astrophysical context as it leads to enhanced gravitational attraction considered as a viable process for star formation. The DA shock transition to its far downstream amplitude is oscillatory in nature due to dust charge ﬂuctuations, the oscillation amplitude and shock width depending on the ratio pd/ch and other plasma parameters.
Linear and nonlinear heavy ion-acoustic waves in a strongly coupled plasma
Ema, S. A., E-mail: ema.plasma@gmail.com; Mamun, A. A. [Department of Physics, Jahangirnagar University, Savar, Dhaka-1342 (Bangladesh); Hossen, M. R. [Deparment of Natural Sciences, Daffodil International University, Sukrabad, Dhaka-1207 (Bangladesh)
2015-09-15
A theoretical study on the propagation of linear and nonlinear heavy ion-acoustic (HIA) waves in an unmagnetized, collisionless, strongly coupled plasma system has been carried out. The plasma system is assumed to contain adiabatic positively charged inertial heavy ion fluids, nonextensive distributed electrons, and Maxwellian light ions. The normal mode analysis is used to study the linear behaviour. On the other hand, the well-known reductive perturbation technique is used to derive the nonlinear dynamical equations, namely, Burgers equation and Korteweg-de Vries (K-dV) equation. They are also numerically analyzed in order to investigate the basic features of shock and solitary waves. The adiabatic effects on the HIA shock and solitary waves propagating in such a strongly coupled plasma are taken into account. It has been observed that the roles of the adiabatic positively charged heavy ions, nonextensivity of electrons, and other plasma parameters arised in this investigation have significantly modified the basic features (viz., polarity, amplitude, width, etc.) of the HIA solitary/shock waves. The findings of our results obtained from this theoretical investigation may be useful in understanding the linear as well as nonlinear phenomena associated with the HIA waves both in space and laboratory plasmas.
Bénisti, Didier
2016-01-01
This paper addresses the linear and nonlinear propagation of an electron wave (EPW), in a three-dimensional geometry, and in a collisionless plasma that may be inhomogeneous, nonstationary, anisotropic and even weakly magnetized. The wave amplitude, together with any hydrodynamic quantity characterizing the plasma (density, temperature,...) are supposed to vary very little within one wavelength or one wave period. Hence, the geometrical optics limit is assumed, and the wave propagation is described by a first order differential equation. This equation explicitly accounts for three-dimensional effects, plasma inhomogeneity, Landau damping, and the collisionless dissipation and electron acceleration due to trapping. It is derived by mixing results obtained from a direct resolution of the Vlasov-Poisson system and from a variational formalism involving a nonlocal Lagrangian density. In a one-dimensional situation, abrupt transitions are predicted in the coefficients of the wave equation. They occur when the sate...
Arbitrary amplitude slow electron-acoustic solitons in three-electron temperature space plasmas
Mbuli, L. N. [South African National Space Agency (SANSA) Space Science, P.O. Box 32, Hermanus 7200, Republic of South Africa (South Africa); University of the Western Cape, Robert Sobukwe Road, Bellville 7535, Republic of South Africa (South Africa); Maharaj, S. K. [South African National Space Agency (SANSA) Space Science, P.O. Box 32, Hermanus 7200, Republic of South Africa (South Africa); Bharuthram, R. [University of the Western Cape, Robert Sobukwe Road, Bellville 7535, Republic of South Africa (South Africa); Singh, S. V.; Lakhina, G. S. [Indian Institute of Geomagnetism, New Panvel (West), Navi Mumbai 410218 (India)
2015-06-15
We examine the characteristics of large amplitude slow electron-acoustic solitons supported in a four-component unmagnetised plasma composed of cool, warm, hot electrons, and cool ions. The inertia and pressure for all the species in this plasma system are retained by assuming that they are adiabatic fluids. Our findings reveal that both positive and negative potential slow electron-acoustic solitons are supported in the four-component plasma system. The polarity switch of the slow electron-acoustic solitons is determined by the number densities of the cool and warm electrons. Negative potential solitons, which are limited by the cool and warm electron number densities becoming unreal and the occurrence of negative potential double layers, are found for low values of the cool electron density, while the positive potential solitons occurring for large values of the cool electron density are only limited by positive potential double layers. Both the lower and upper Mach numbers for the slow electron-acoustic solitons are computed and discussed.
A mode filter for plasma waves in the Hall-MHD approximation
C. Vocks
Full Text Available A filter method is presented which allows a qualitative and quantitative identification of wave modes observed with plasma experiments on satellites. Hitherto existing mode filters are based on the MHD theory and thus they are restricted to low frequencies well below the ion cyclotron frequency. The present method is generalized to cover wave modes up to the characteristic ion frequencies. The spectral density matrix determined by the observations is decomposed using the eigenvectors of the linearized Hall-MHD equations. As the wave modes are dispersive in this formalism, a precise determination of the k->-vectors requires the use of multi-point measurements. Therefore the method is particularly relevant to multi-satellite missions. The method is tested using simulated plasma data. The Hall-MHD filter is able to identify the modes excited in the model plasma and to assign the correct energetic contributions. By comparison with the former method it is shown that the simple MHD filter leads to large errors if the frequency is not well below the ion cyclotron frequency. Further the range of validity of the linear theory is examined rising the simulated wave amplitudes.
Key words. Magnetospheric physics (MHD waves and instabilities; plasma waves and instabilities
Effects of Schwarzschild Geometry on Isothermal Plasma Wave Dispersion
Sharif, M.; Sheikh, Umber
2007-01-01
The behavior of isothermal plasma waves has been analyzed near the Schwarzschild horizon. We consider a non-rotating background with non-magnetized and magnetized plasmas. The general relativistic magnetohydrodynamical equations for the Schwarzschild planar analogue spacetime with an isothermal state of the plasma are formulated. The perturbed form of these equations is linearized and Fourier analyzed by introducing simple harmonic waves. The determinant of these equations in each case leads ...
Second harmonic plasma emission involving ion sound waves
Cairns, Iver H.
1987-01-01
The theory for second harmonic plasma emission by the weak turbulence (or random phase) processes L + L + or - S to T, proceeding in two three-wave steps, L + or - S to L prime and L + L prime to T, where L, S and T denote Langmuir, ion sound and electromagnetic waves, respectively, is developed. Kinematic constraints on the characteristics and growth lengths of waves participating in the wave processes, and constraints on the characteristics of the source plasma, are derived. Limits on the brightness temperature of the radiation and the levels of the L prime and S waves are determined. Expressions for the growth rates and path-integrated wave temperatures are derived for simple models of the wave spectra and source plasma.
Cyclotron waves in a non-neutral plasma column
Dubin, Daniel H. E. [Department of Physics, University of California at San Diego, La Jolla, California 92093 (United States)
2013-04-15
A kinetic theory of linear electrostatic plasma waves with frequencies near the cyclotron frequency {Omega}{sub c{sub s}} of a given plasma species s is developed for a multispecies non-neutral plasma column with general radial density and electric field profiles. Terms in the perturbed distribution function up to O(1/{Omega}{sub c{sub s}{sup 2}}) are kept, as are the effects of finite cyclotron radius r{sub c} up to O(r{sub c}{sup 2}). At this order, the equilibrium distribution is not Maxwellian if the plasma temperature or rotation frequency is not uniform. For r{sub c}{yields}0, the theory reproduces cold-fluid theory and predicts surface cyclotron waves propagating azimuthally. For finite r{sub c}, the wave equation predicts that the surface wave couples to radially and azimuthally propagating Bernstein waves, at locations where the wave frequency equals the local upper hybrid frequency. The equation also predicts a second set of Bernstein waves that do not couple to the surface wave, and therefore have no effect on the external potential. The wave equation is solved both numerically and analytically in the WKB approximation, and analytic dispersion relations for the waves are obtained. The theory predicts that both types of Bernstein wave are damped at resonances, which are locations where the Doppler-shifted wave frequency matches the local cyclotron frequency as seen in the rotating frame.
The energy density of a Landau damped plasma wave
Best, R. W. B.
1999-01-01
In this paper some theories about the energy of a Landau damped plasma wave are discussed and new initial conditions are proposed. Analysis of a wave packet, rather than an infinite wave, gives a clear picture of the energy transport from field to particles. Initial conditions are found which excite
Does the Decay Wave Propagate Forwards in Dusty Plasmas?
谢柏松
2002-01-01
The decay interaction of the ion acoustic wave in a dusty plasma with variable-charge dust grains is studied.Even if strong charging relaxation for dust grains and the short wavelength regime for ion waves are included, it is found that the decay wave must be backward propagating.
Evidence for Langmuir wave collapse in the interplanetary plasma
Kellogg, Paul J.; Goetz, K.; Howard, R. L.; Monson, S. J.
1992-01-01
With the Fast Envelope Sampler part of the URAP experiment on Ulysses, there is observed much rapidly varying structure in plasma waves in the solar wind. Extremely narrow (1 ms) structures observed together with electrostatic Langmuir waves, as well as some broader Langmuir wave packets are discussed.
Linear theory of plasma filled backward wave oscillator
Preeti Vyas; Arti Gokhale; Y Choyal; K P Maheshwari
2001-05-01
An analytical and numerical study of backward wave oscillator (BWO) in linear regime is presented to get an insight into the excitation of electromagnetic waves as a result of the interaction of the relativistic electron beam with a slow wave structure. The effect of background plasma on the BWO instability is also presented.
Nonlinear dust acoustic waves with polarization force effects in Kappa distribution plasma
Chen, Hui; Zhou, Suyun; Luo, Rongxiang; Liu, Sanqiu
2017-01-01
The propagation characteristics of dust acoustic solitary waves (DASWs) in dusty plasmas with the effects of polarization force and superthermal ions are studied. First, the polarization force induced by superthermal ions is obtained. It is shown that the superthermality of background ions affect the Debye screening of dust grains as well as the polarization force significantly. Then for small amplitude solitary waves, the KdV equation is obtained by applying the reductive perturbation technique. And for the arbitrary amplitude solitary waves, the Sagdeev potential method is employed and the Sagdeev potential is analyzed. In both case, the effects of the polarization force associated the ions’ superthermality on the characteristic of the DASWs are analyzed.
Surface wave and linear operating mode of a plasma antenna
Bogachev, N. N., E-mail: bgniknik@yandex.ru; Bogdankevich, I. L.; Gusein-zade, N. G.; Rukhadze, A. A. [Russian Academy of Sciences, Prokhorov General Physics Institute (Russian Federation)
2015-10-15
The relation between the propagation conditions of a surface electromagnetic wave along a finiteradius plasma cylinder and the linear operating mode of a plasma antenna is investigated. The solution to the dispersion relation for a surface wave propagating along a finite-radius plasma cylinder is analyzed for weakly and strongly collisional plasmas. Computer simulations of an asymmetrical plasma dipole antenna are performed using the KARAT code, wherein the dielectric properties of plasma are described in terms of the Drude model. The plasma parameters corresponding to the linear operating mode of a plasma antenna are determined. It is demonstrated that the characteristics of the plasma antenna in this mode are close to those of an analogous metal antenna.
Broadband plasma waves observed in the polar cap boundary layer: Polar
Tsurutani, B. T.; Lakhina, G. S.; Ho, C. M.; Arballo, J. K.; Galvan, C.; Boonsiriseth, A.; Pickett, J. S.; Gurnett, D. A.; Peterson, W. K.; Thorne, R. M.
1998-08-01
Polar observations indicate the presence of intense broadband plasma waves nearly all of the time (96% occurrence frequency in this study) near the apogee of the Polar trajectory (~6-8RE). The region of wave activity bounds the dayside (0500 to 1800 LT) polar cap magnetic fields, and we thus call these waves polar cap boundary layer (PCBL) waves. The waves are spiky signals spanning a broad frequency range from ~101 to 2×104Hz. The waves have a rough power law spectral shape. The wave magnetic component has on average a f-2.7 frequency dependence and appears to have an upper frequency cutoff of ~(6-7)×103Hz, which is the electron cyclotron frequency. The electric component has on average a f-2.2 frequency dependence and extends up to ~2×104Hz. The frequency dependences of the waves and the amplitude ratios of B'/E' indicate a possible mixture of obliquely propagating electromagnetic whistler mode waves plus electrostatic waves. There are no clear intensity peaks in either the magnetic or electric spectra which can identify the plasma instability responsible for the generation of the PCBL waves. The wave character (spiky nature, frequency dependence and admixture of electromagnetic and electrostatic components) and intensity are quite similar to those of the low-latitude boundary layer (LLBL) waves detected at and inside the low-latitude dayside magnetopause. Because of the location of the PCBL waves just inside the polar cap magnetic field lines, it is natural to assume that these waves are occurring on the same magnetic field lines as the LLBL waves, but at lower altitudes. Because of the similar wave intensities at both locations and the occurrence at all local times, we rule out an ionospheric source. We also find a magnetosheath origin improbable. The most likely scenario is that the waves are locally generated by field-aligned currents or current gradients. We find a strong relationship between the presence of ionospheric and magnetosheath ions and the
ALFVEN WAVES IN A PARTIALLY IONIZED TWO-FLUID PLASMA
Soler, R.; Ballester, J. L.; Terradas, J. [Departament de Fisica, Universitat de les Illes Balears, E-07122 Palma de Mallorca (Spain); Carbonell, M., E-mail: roberto.soler@uib.es, E-mail: joseluis.ballester@uib.es, E-mail: jaume.terradas@uib.es, E-mail: marc.carbonell@uib.es [Departament de Matematiques i Informatica, Universitat de les Illes Balears, E-07122 Palma de Mallorca (Spain)
2013-04-20
Alfven waves are a particular class of magnetohydrodynamic waves relevant in many astrophysical and laboratory plasmas. In partially ionized plasmas the dynamics of Alfven waves is affected by the interaction between ionized and neutral species. Here we study Alfven waves in a partially ionized plasma from the theoretical point of view using the two-fluid description. We consider that the plasma is composed of an ion-electron fluid and a neutral fluid, which interact by means of particle collisions. To keep our investigation as general as possible, we take the neutral-ion collision frequency and the ionization degree as free parameters. First, we perform a normal mode analysis. We find the modification due to neutral-ion collisions of the wave frequencies and study the temporal and spatial attenuation of the waves. In addition, we discuss the presence of cutoff values of the wavelength that constrain the existence of oscillatory standing waves in weakly ionized plasmas. Later, we go beyond the normal mode approach and solve the initial-value problem in order to study the time-dependent evolution of the wave perturbations in the two fluids. An application to Alfven waves in the low solar atmospheric plasma is performed and the implication of partial ionization for the energy flux is discussed.
Nonlinear Alfvén Waves in a Vlasov Plasma
Bell, T.F.
1965-01-01
Stationary solutions to the nonlinear Vlasov—Boltzmann equations are considered which represent one-dimensional electromagnetic waves in a hot magnetoplasma. These solutions appear in arbitrary reference frames as circularly polarized, sinusoidal waves of unlimited amplitude, i.e., as nonlinear...... Alfvén waves. Solutions are found implicitly by deriving a set of integral dispersion relations which link the wave characteristics with the particle distribution functions. A physical discussion is given of the way in which the Alfvén waves can trap particles, and it is shown that the presence...
Itsuki Banno; Kazumi Fujima
2007-01-01
A determinantal formula is developed for direct evaluation of transition amplitude without solving the wave equation in a one-dimensional potential scattering system. Our formulation is based on the principle that a desired quantity can be extracted from the wave operator, which is the master operator maintaining all the information of the system. This principle is tested in a simplified system, I.e., in a one-dimensional potential scattering system. We are now developing a formula for direct evaluation of near-field amplitude to design a system, in which local Geld enhancement is desired.
Blankleider, B.; Afnan, I. R.
1985-04-01
The polarization observables of the reactions parrow parrow --> π+d, parrowp --> darrowπ+, and πdarrow --> πdarrow are investigated. Expressions relating these observables directly to (LSJ) partial wave amplitudes are derived and tabulations of the partial wave contributions are given for some of the observables. Examples are given of how such tabulations can be useful for optimizing the connection between theory and experiment and in suggesting possible new experiments. All observables are also calculated numerically using a unitary few-body model of the NN-πNN system to generate the amplitudes. Sensitivity to the choice of P11 interaction is investigated.
Blankleider, B.; Afnan, I.R.
1985-04-01
The polarization observables of the reactions parrow parrow ..-->.. ..pi../sup +/d, parrowp ..-->.. darrow..pi../sup +/, and ..pi..darrow ..-->.. ..pi..darrow are investigated. Expressions relating these observables directly to (LSJ) partial wave amplitudes are derived and tabulations of the partial wave contributions are given for some of the observables. Examples are given of how such tabulations can be useful for optimizing the connection between theory and experiment and in suggesting possible new experiments. All observables are also calculated numerically using a unitary few-body model of the NN-..pi..NN system to generate the amplitudes. Sensitivity to the choice of P/sub 11/ interaction is investigated.
Saha, Asit
2017-03-01
Positron acoustic shock waves (PASHWs) in unmagnetized electron-positron-ion (e-p-i) plasmas consisting of mobile cold positrons, immobile positive ions, q-nonextensive distributed electrons, and hot positrons are studied. The cold positron kinematic viscosity is considered and the reductive perturbation technique is used to derive the Burgers equation. Applying traveling wave transformation, the Burgers equation is transformed to a one dimensional dynamical system. All possible vector fields corresponding to the dynamical system are presented. We have analyzed the dynamical system with the help of potential energy, which helps to identify the stability and instability of the equilibrium points. It is found that the viscous force acting on cold mobile positron fluid is a source of dissipation and is responsible for the formation of the PASHWs. Furthermore, fully nonlinear arbitrary amplitude positron acoustic waves are also studied applying the theory of planar dynamical systems. It is also observed that the fundamental features of the small amplitude and arbitrary amplitude PASHWs are significantly affected by the effect of the physical parameters q e , q h , μ e , μ h , σ , η , and U. This work can be useful to understand the qualitative changes in the dynamics of nonlinear small amplitude and fully nonlinear arbitrary amplitude PASHWs in solar wind, ionosphere, lower part of magnetosphere, and auroral acceleration regions.
Thermal effects on seeded finite ion temperature, high amplitude plasma blobs
Held, M; Madsen, J; Kendl, A
2016-01-01
Thermal effects on the perpendicular convection of seeded pressure blobs in the scrape-off layer of magnetised fusion plasmas are investigated. Our numerical study is based on a four field full-F gyrofluid model, which entails the consistent description of high fluctuation amplitudes and dynamic finite Larmor radius effects. We find that a temperature perturbation increases the maximal blob velocity and that a finite Larmor radius contributes to highly compact blob structures with finite poloidal motion. An extensive parameter study reveals that a smooth transition to this compact blob regime occurs when the finite Larmor radius effect strength, defined by the ratio of the ion diamagnetic to the perpendicular vorticity, exceeds unity. The maximal blob velocities excellently agree with the inertial velocity scaling law over more than an order of magnitude. We show that the finite Larmor radius effect strength affects the radial transport and verify the here presented empirical scaling law for the maximal radia...
Choi, Ki Yong; No, Hee Cheon [Korea Advanced Institute of Science and Technology, Taejon (Korea, Republic of)
1998-12-31
The calibrating method for an electrochemical probe, neglecting the effect of the normal velocity on the mass transport, can cause large errors when applied to the measurement of wall shear rates in thin wavy flow with large amplitude waves. An extended calibrating method is developed to consider the contributions of the normal velocity. The inclusion of the turbulence-induced normal velocity term is found to have a negligible effect on the mass transfer coefficient. The contribution of the wave-induced normal velocity can be classified on the dimensionless parameter, V. If V is above a critical value of V, V{sub crit}, the effects of the wave-induced normal velocity become larger with an increase in V. While its effects negligible for inversely. The present inverse method can predict the unknown shear rate more accurately in thin wavy flow with large amplitude waves than the previous method. 18 refs., 8 figs. (Author)
Rehman, M. A.; Qureshi, M. N. S. [Department of Physics, GC University, Kachery Road, Lahore 54000 (Pakistan); Shah, H. A. [Department of Physics, Forman Christian College, Ferozepur Road, Lahore 54600 (Pakistan); Masood, W. [COMSATS, Institute of Information Technology, Park Road, Chak Shehzad, Islamabad 44000 (Pakistan); National Centre for Physics (NCP) Shahdra Valley Road, Islamabad (Pakistan)
2015-10-15
Nonlinear circularly polarized Alfvén waves are studied in magnetized nonrelativistic, relativistic, and ultrarelativistic degenerate Fermi plasmas. Using the quantum hydrodynamic model, Zakharov equations are derived and the Sagdeev potential approach is used to investigate the properties of the electromagnetic solitary structures. It is seen that the amplitude increases with the increase of electron density in the relativistic and ultrarelativistic cases but decreases in the nonrelativistic case. Both right and left handed waves are considered, and it is seen that supersonic, subsonic, and super- and sub-Alfvénic solitary structures are obtained for different polarizations and under different relativistic regimes.
Electro-acoustic solitary waves and double layers in a quantum plasma
Dip, P. R.; Hossen, M. A.; Salahuddin, M.; Mamun, A. A.
2017-02-01
A meticulous theoretical investigation has carried out to study the properties related to the higher-order nonlinearity of the electro-acoustic waves, specifically ion-acoustic (IA) waves in an unmagnetized, collisionless, quantum electron-positron-ion (EPI) plasma. The plasma system is supposed to be formed of positively charged inertial heavy ions, inertialess electrons and positrons. The reductive perturbation technique is employed to derive the modified Korteweg-de Vries (mK-dV) equation to analyze the solitary waves (SWs), and the standard Gardner (SG) equation to analyze the higher-order SWs as well as double layers (DLs). The basic features (viz. amplitude, width, phase speed, etc.) of the IA SWs and DLs are examined. The comparison between the mK-dV SWs and SG SWs is also made. It is found that the amplitude, width, phase speed, etc. of the IA SWs and DLs are significantly modified by the effects of the both Fermi temperatures as well as pressures and Bohm potentials of electrons and positrons. Our findings may be useful in explaining the physics behind the formation of the IA waves in both astrophysical and laboratory EPI plasmas (viz. white dwarfs, laser-solid matter interaction experiments, etc.).
Ion-acoustic rogue waves and breathers in relativistically degenerate electron-positron plasmas
Abdikian, A.; Ismaeel, S.
2017-08-01
In this paper, we employ a weakly relativistic fluid model to study the nonlinear amplitude modulation of electrostatic waves in an unmagnetized electron-positron-ion plasma. It is assumed that the degeneracy pressure law for electrons and positrons follows the Chandrasekhar limit of state whereas ions are warm and classical. The hydrodynamic approach along with the perturbation method have been applied to obtain the corresponding nonlinear Schrödinger equation (NLSE) in which nonlinearity is in balance with the dispersive terms. Using the NLSE, we could evaluate the modulational instability to show that various types of localized ion acoustic excitations exist in the form of either bright-type envelope solitons or dark-type envelope solitons. The regions of the stable and unstable envelope wave have been confined punctually for various regimes. Furthermore, it is proposed that the exact solutions of the NLSE for breather waves are the rogue waves (RWs), Akhmediev breather (AB), and Kuznetsov-Ma breather (KM) soliton. In order to show that the characteristics of breather structures is influenced by the plasma parameters (namely, relativistic parameter, positron concentration, and ionic temperature), the relevant numerical analysis of the NLSE is examined. In particular, it is observed that by increasing the values of the mentioned plasma parameters, the amplitude of the RWs will be decreased. Our results help researchers to explain the formation and dynamics of nonlinear electrostatic excitations in super dense astrophysical regimes.
Nonlinear behavior of electron acoustic waves in an un-magnetized plasma
Dutta, Manjistha; Khan, Manoranjan [Department of Instrumentation Science, Jadavpur University, Kolkata 700 032 (India); Chakrabarti, Nikhil [Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700 064 (India); Roychoudhury, Rajkumar [Indian Statistical Institute, Kolkata 700 108 (India)
2011-10-15
The nonlinear electron acoustic wave, which is found in the earth's magnetosphere by satellite observations, is studied analytically by Lagrangian fluid description. The basic linear mode is observed in a two temperature electron species plasma where ions form stationary charge neutral background. We have obtained nonlinear description of this mode, which depends on both time and space. A possible solution shows a soliton like structure, which is localized in space, and the amplitude increases with time in the absence of dispersion. Small dispersive correction, however, shows spread of the solution in space. This method can be generalized to study the nonlinear behavior of a general class of multispecies plasma.
M AMINA; S A EMA; A A MAMUN
2017-06-01
A rigorous theoretical investigation has been carried out on the propagation of nonplanar (cylindrical and spherical) dust-acoustic shock waves (DASHWs) in a collisionless four-component unmagnetized dusty plasmasystem containing massive, micron-sized, positively and negatively charged inertial dust grains along with $q$ (nonextensive) distributed electrons and ions. The well-known reductive perturbation technique has been used to derive the modified Burgers equation (which describes the shock wave properties) and its numerical solution. It has been observed that the effects of charged dust grains of opposite polarity, nonextensivity of electrons and ions, and different dusty plasma parameters have significantly modified the fundamental properties (viz., polarity, amplitude, width, etc.) of the shock waves. The properties of DASHWs in nonplanar geometry are found tobe significantly different from those in one-dimensional planar geometry. The findings of our results from this theoretical investigation may be useful in understanding the nonlinear features of localized electrostatic disturbancesin both space and laboratory dusty plasmas.
Damping solitary wave under the second and third boundary condition of a viscous plasma
Li, G.; Ren, Y.-Q.
2016-08-01
In this paper, the solitary waves of a viscous plasma confined in a cylindrical pipe is investigated under two types of boundary condition. By using the reductive perturbation theory, a quasi-KdV equation is derived and a damping solitary wave is obtained. It is found that the damping rate increases with the viscosity coefficient of the plasma ν ' increasing and the radius of the cylindrical pipe R decreasing for second and third boundary condition. The magnitude of the damping rate is also dominated by boundary condition type. From the fact that the amplitude reduces rapidly when R approaches zero or ν ' approaches infinite, we confirm the existence of a damping solitary wave.
On the role of ion-scale whistler waves in space and astrophysical plasma turbulence
Comişel, Horia; Nariyuki, Yasuhiro; Narita, Yasuhito; Motschmann, Uwe
2016-11-01
Competition of linear mode waves is studied numerically to understand the energy cascade mechanism in plasma turbulence on ion-kinetic scales. Hybrid plasma simulations are performed in a text">3-D simulation box by pumping large-scale Alfvén waves on the fluid scale. The result is compared with that from our earlier text">2-D simulations. We find that the whistler mode is persistently present both in the text">2-D and text">3-D simulations irrespective of the initial setup, e.g., the amplitude of the initial pumping waves, while all the other modes are excited and damped such that the energy is efficiently transported to thermal energy over non-whistler mode. The simulation results suggest that the whistler mode could transfer the fluctuation energy smoothly from the fluid scale down to the electron-kinetic scale, and justifies the notion of whistler turbulence.
Wei, Gang; Du, Hui; Xu, XiaoHui; Zhang, YuanMing; Qu, ZiYun; Hu, TianQun; You, YunXiang
2014-01-01
A principle of generating the nonlinear large-amplitude internal wave in a stratified fluid tank with large cross-section is proposed according to the `jalousie' control mode. A new wave-maker based on the principle was manufactured and the experiments on the generation and evolution of internal solitary wave were conducted. Both the validity of the new device and applicability range of the KdV-type internal soliton theory were tested. Furthermore, a measurement technique of hydrodynamic load of internal waves was developed. By means of accurately measuring slight variations of internal wave forces exerted on a slender body in the tank, their interaction characteristics were determined. It is shown that through establishing the similarity between the model scale in the stratified fluid tank and the full scale in the numerical simulation the obtained measurement results of internal wave forces are confirmed to be correct.
Nonlinear wave structures in collisional plasma of auroral E-region ionosphere
A. V. Volosevich
Full Text Available Studies of the auroral plasma with small-scale inhomogenieties producing the VHF-radar reflections (radar aurora when observed in conditions of the saturated Farley-Buneman instability within the auroral E region, show strong nonlinear interactions and density fluctuations of 5–15%. Such nonlinearity and high fluctation amplitudes are inconsistent with the limitations of the weak turbulence theory, and thus a theory for arbitrary amplitudes is needed. To this end, a nonlinear theory is described for electrostatic MHD moving plasma structures of arbitrary amplitude for conditions throughout the altitude range of the collisional auroral E region. The equations are derived, from electron and ion motion self-consistent with the electric field, for the general case of the one-dimensional problem. They take into account nonlinearity, electron and ion inertia, diffusion, deviation from quasi-neutrality, and dynamical ion viscosity. The importance of the ion viscosity for dispersion is stressed, while deviation from the quasi-neutrality can be important only at rather low plasma densities, not typical for the auroral E region. In a small amplitude limit these equations have classical nonlinear solutions of the type of "electrostatic shock wave" or of knoidal waves. In a particular case these knoidal waves degrade to a dissipative soliton. A two-dimensional case of a quasi-neutral plasma is considered in the plane perpendicular to the magnetic field by way of the Poisson brackets, but neglecting the nonlinearity and ion inertia. It is shown that in these conditions an effective saturation can be achieved at the stationary turbulence level of order of 10%.
Nonlinear propagation of weakly relativistic ion-acoustic waves in electron–positron–ion plasma
M G HAFEZ; M R TALUKDER; M HOSSAIN ALI
2016-11-01
This work presents theoretical and numerical discussion on the dynamics of ion-acoustic solitary wave for weakly relativistic regime in unmagnetized plasma comprising non-extensive electrons, Boltzmann positrons and relativistic ions. In order to analyse the nonlinear propagation phenomena, the Korteweg–de Vries(KdV) equation is derived using the well-known reductive perturbation method. The integration of the derived equation is carried out using the ansatz method and the generalized Riccati equation mapping method. The influenceof plasma parameters on the amplitude and width of the soliton and the electrostatic nonlinear propagation of weakly relativistic ion-acoustic solitary waves are described. The obtained results of the nonlinear low-frequencywaves in such plasmas may be helpful to understand various phenomena in astrophysical compact object and space physics.
Electron acceleration during the decay of nonlinear Whistler waves in low-beta electron-ion plasma
Umeda, Takayuki; Saito, Shinji [Solar-Terrestrial Environment Laboratory, Nagoya University, Nagoya City, Aichi 464-8601 (Japan); Nariyuki, Yasuhiro, E-mail: umeda@stelab.nagoya-u.ac.jp, E-mail: saito@stelab.nagoya-u.ac.jp, E-mail: nariyuki@edu.u-toyama.ac.jp [Faculty of Human Development, University of Toyama, Toyama City, Toyama 930-8555 (Japan)
2014-10-10
Relativistic electron acceleration through dissipation of a nonlinear, short-wavelength, and monochromatic electromagnetic whistler wave in low-beta plasma is investigated by utilizing a one-dimensional fully relativistic electromagnetic particle-in-cell code. The nonlinear (large-amplitude) parent whistler wave decays through the parametric instability which enhances electrostatic ion acoustic waves and electromagnetic whistler waves. These waves satisfy the condition of three-wave coupling. Through the decay instability, the energy of electron bulk velocity supporting the parent wave is converted to the thermal energy perpendicular to the background magnetic field. Increase of the perpendicular temperature triggers the electron temperature anisotropy instability which generates broadband whistler waves and heats electrons in the parallel direction. The broadband whistler waves are inverse-cascaded during the relaxation of the electron temperature anisotropy. In lower-beta conditions, electrons with a pitch angle of about 90° are successively accelerated by inverse-cascaded whistler waves, and selected electrons are accelerated to over a Lorentz factor of 10. The result implies that the nonlinear dissipation of a finite-amplitude and short-wavelength whistler wave plays an important role in producing relativistic nonthermal electrons over a few MeV especially at lower beta plasmas.
Bruneau, B.; Korolov, I.; Lafleur, T.; Gans, T.; O'Connell, D.; Greb, A.; Derzsi, A.; Donkó, Z.; Brandt, S.; Schüngel, E.; Schulze, J.; Johnson, E.; Booth, J.-P.
2016-04-01
We report investigations of capacitively coupled carbon tetrafluoride (CF4) plasmas excited with tailored voltage waveforms containing up to five harmonics of a base frequency of 5.5 MHz. The impact of both the slope asymmetry, and the amplitude asymmetry, of these waveforms on the discharge is examined by combining experiments with particle-in-cell simulations. For all conditions studied herein, the discharge is shown to operate in the drift-ambipolar mode, where a comparatively large electric field in the plasma bulk (outside the sheaths) is the main mechanism for electron power absorption leading to ionization. We show that both types of waveform asymmetries strongly influence the ion energy at the electrodes, with the particularity of having the highest ion flux on the electrode where the lowest ion energy is observed. Even at the comparatively high pressure (600 mTorr) and low fundamental frequency of 5.5 MHz used here, tailoring the voltage waveforms is shown to efficiently create an asymmetry of both the ion energy and the ion flux in geometrically symmetric reactors.
Bruneau, B., E-mail: bastien.bruneau@polytechnique.edu; Johnson, E. [LPICM-CNRS, Ecole Polytechnique, 91128 Palaiseau (France); Korolov, I.; Derzsi, A.; Donkó, Z. [Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, Hungarian Academy of Sciences, Konkoly-Thege Miklós Str. 29-33, H-1121 Budapest (Hungary); Lafleur, T.; Booth, J.-P. [LPP, Ecole Polytechnique-CNRS-Univ Paris-Sud-UPMC, 91128 Palaiseau (France); Gans, T.; O' Connell, D.; Greb, A. [Department of Physics, York Plasma Institute, University of York, Heslington, York YO10 5DD (United Kingdom); Brandt, S.; Schüngel, E.; Schulze, J. [Department of Physics, West Virginia University, Morgantown, West Virginia 26506-6315 (United States)
2016-04-28
We report investigations of capacitively coupled carbon tetrafluoride (CF{sub 4}) plasmas excited with tailored voltage waveforms containing up to five harmonics of a base frequency of 5.5 MHz. The impact of both the slope asymmetry, and the amplitude asymmetry, of these waveforms on the discharge is examined by combining experiments with particle-in-cell simulations. For all conditions studied herein, the discharge is shown to operate in the drift-ambipolar mode, where a comparatively large electric field in the plasma bulk (outside the sheaths) is the main mechanism for electron power absorption leading to ionization. We show that both types of waveform asymmetries strongly influence the ion energy at the electrodes, with the particularity of having the highest ion flux on the electrode where the lowest ion energy is observed. Even at the comparatively high pressure (600 mTorr) and low fundamental frequency of 5.5 MHz used here, tailoring the voltage waveforms is shown to efficiently create an asymmetry of both the ion energy and the ion flux in geometrically symmetric reactors.
Helicon waves in uniform plasmas. IV. Bessel beams, Gendrin beams, and helicons
Urrutia, J. M.; Stenzel, R. L.
2016-05-01
Electromagnetic waves in the low frequency whistler mode regime are investigated experimentally and by digital data superposition. The radiation from a novel circular antenna array is shown to produce highly collimated helicon beams in a uniform unbounded plasma. The differences to Bessel beams in free space are remarked upon. Low divergence beams arise from the parallel group velocity of whistlers with phase velocity either along the guide field or at the Gendrin angle. Waves with angular momentum are produced by phasing the array in the circular direction. The differences in the field topologies for positive and negative modes numbers are shown. It is also shown that in uniform plasmas, the radial amplitude profile of the waves depends on the antenna field topology. Thus, there are no helicon "eigenmodes" with radial Bessel function profiles in uniform plasmas. It is pointed out that phase measurements in helicon devices indicate radial wave propagation which is inconsistent with helicon eigenmode theory based on paraxial wave propagation. Trivelpiece-Gould modes also exist in uniform unbounded plasmas.
Kinetic Alfvén solitary and rogue waves in superthermal plasmas
Bains, A. S.; Li, Bo, E-mail: bbl@sdu.edu.cn; Xia, Li-Dong [Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment, School of Space Science and Physics, Shandong University at Weihai, 264209 Weihai (China)
2014-03-15
We investigate the small but finite amplitude solitary Kinetic Alfvén waves (KAWs) in low β plasmas with superthermal electrons modeled by a kappa-type distribution. A nonlinear Korteweg-de Vries (KdV) equation describing the evolution of KAWs is derived by using the standard reductive perturbation method. Examining the dependence of the nonlinear and dispersion coefficients of the KdV equation on the superthermal parameter κ, plasma β, and obliqueness of propagation, we show that these parameters may change substantially the shape and size of solitary KAW pulses. Only sub-Alfvénic, compressive solitons are supported. We then extend the study to examine kinetic Alfvén rogue waves by deriving a nonlinear Schrödinger equation from the KdV equation. Rational solutions that form rogue wave envelopes are obtained. We examine how the behavior of rogue waves depends on the plasma parameters in question, finding that the rogue envelopes are lowered with increasing electron superthermality whereas the opposite is true when the plasma β increases. The findings of this study may find applications to low β plasmas in astrophysical environments where particles are superthermally distributed.
Excitation of surface plasma waves over corrugated slow-wave structure
Ashim P Jain; Jetendra Parashar
2005-08-01
A microwave propagating along vacuum–dielectric–plasma interface excites surface plasma wave (SPW). A periodic slow-wave structure placed over dielectric slows down the SPW. The phase velocity of slow SPW is sensitive to height, periodicity, number of periods, thickness and the separation between dielectric and slow-wave structure. These slow SPW can couple the microwave energy to the plasma and can sustain the discharge. The efficiency of the power coupling is few per cent and is sensitive to separation between dielectric and slow-wave structure.
Chomaz, Jean-Marc; Ortiz, Sabine; Lerisson, Gaétan
2016-11-01
Triadic instability is a very generic mechanism by which a primary wave of finite amplitude is destabilized by two secondary (daugther) waves forming a resonant triad. For gravity wave in the ocean, as shown by Phillips, O.M. (CUP, 1967) the resonant triads form several continuous family that may be represented in twodimension (2D) as resonant lines in the 2D wave vector space of the secondary wave. We show here that the crossing of two od these branches may results in a double triadic instability where the instability is reduced. Building on McEwan, A.D. & Plumb, R.A. (Dyn. Atm. & Oceans, 1977) we show that this double triadic instability stabilization domain expends from a singular point to a finite significant region when the amplitude of the primary wave is increased. Comparison with direct computation of the instability branches shows that, from very small to order unity primary wave amplitude, the theoretical prediction stay valid and is able to explain the strong departure from the classical triadic instability theory. Support by DGA is acknowledged.
Wang, Dun; Kawakatsu, Hitoshi; Zhuang, Jiancang; Mori, Jim; Maeda, Takuto; Tsuruoka, Hiroshi; Zhao, Xu
2017-06-01
Fast estimates of magnitude and source extent of large earthquakes are fundamental for disaster mitigation. However, resolving these estimates within 10-20 min after origin time remains challenging. Here we propose a robust algorithm to resolve magnitude and source length of large earthquakes using seismic data recorded by regional arrays and global stations. We estimate source length and source duration by backprojecting seismic array data. Then the source duration and the maximum amplitude of the teleseismic P wave displacement waveforms are used jointly to estimate magnitude. We apply this method to 74 shallow earthquakes that occurred within epicentral distances of 30-85° to Hi-net (2004-2014). The estimated magnitudes are similar to moment magnitudes estimated from W-phase inversions (U.S. Geological Survey), with standard deviations of 0.14-0.19 depending on the global station distributions. Application of this method to multiple regional seismic arrays could benefit tsunami warning systems and emergency response to large global earthquakes.
Continuity and asymptotic behaviors for a shallow water wave model with moderate amplitude
Zhou, Shouming; Qiao, Zhijun; Mu, Chunlai; Wei, Long
2017-07-01
In this paper, we study continuity and persistence for a nonlinear evolution equation describing the free surface of shallow water wave with a moderate amplitude, which was proposed by Constantin and Lannes [7]. By the approach for approximate solutions and well-posedness estimates, we obtain two sequences of solution for Constantin-Lannes equation, which are bounded in the Sobolev space Hs (R) with s > 3 / 2, and the distance between the two sequences is lower-bounded by a positive constant for any time t, but converges to zero at the initial time. This implies that the solution map is not uniformly continuous. Furthermore, the solution map for Constantin-Lannes equation is shown Hölder-continuous in Hr-topology for all 0 ≤ r < s with exponent α depending on s and r. In addition, we also investigate the asymptotic behaviors of the strong solutions to Constantin-Lannes equation at infinity within its lifespan provided the initial data in weighted Lϕp : =Lp (R ,ϕp dx) spaces.
Phase and amplitude wave front sensing and reconstruction with a modified plenoptic camera
Wu, Chensheng; Ko, Jonathan; Nelson, William; Davis, Christopher C.
2014-10-01
A plenoptic camera is a camera that can retrieve the direction and intensity distribution of light rays collected by the camera and allows for multiple reconstruction functions such as: refocusing at a different depth, and for 3D microscopy. Its principle is to add a micro-lens array to a traditional high-resolution camera to form a semi-camera array that preserves redundant intensity distributions of the light field and facilitates back-tracing of rays through geometric knowledge of its optical components. Though designed to process incoherent images, we found that the plenoptic camera shows high potential in solving coherent illumination cases such as sensing both the amplitude and phase information of a distorted laser beam. Based on our earlier introduction of a prototype modified plenoptic camera, we have developed the complete algorithm to reconstruct the wavefront of the incident light field. In this paper the algorithm and experimental results will be demonstrated, and an improved version of this modified plenoptic camera will be discussed. As a result, our modified plenoptic camera can serve as an advanced wavefront sensor compared with traditional Shack- Hartmann sensors in handling complicated cases such as coherent illumination in strong turbulence where interference and discontinuity of wavefronts is common. Especially in wave propagation through atmospheric turbulence, this camera should provide a much more precise description of the light field, which would guide systems in adaptive optics to make intelligent analysis and corrections.
iResum: a new paradigm for resumming gravitational wave amplitudes
Nagar, Alessandro
2016-01-01
We introduce a new method to improve the resummation of the post-Newtonian (PN), circularized, multipolar waveform that enters the effective-one-body (EOB) theory of coalescing, nonprecessing, spinning black hole binaries (BBHs). We focus on the residual (post-factorized) waveform amplitude corrections $f_{\\ell m}$ introduced by Damour and Nagar~[Phys. Rev. D~76, 064028 (2007)]. In the (nonspinning) test-particle limit, using 20PN-accurate analytical gravitational wave fluxes, we compute the usual functions $\\rho_{\\ell m}\\equiv (f_{\\ell m})^{1/\\ell}=\\rho^{\\rm orb}_{\\ell m}+\\rho^{\\rm S}_{\\ell m}$ (where $\\rho^{\\rm S}_{\\ell m}$ and $\\rho_{\\ell m}^{\\rm orb}$ are the spin and orbital contributions) at 20PN following Pan et al. [Phys. Rev. D 83, 064003 (2011)]. When $m$ is even and the angular momentum of the supermassive black hole is large (and explicitly discussing $\\ell=m=2$) the usual $\\rho_{\\ell m}$, even at high PN order, are inaccurate with respect to the "exact" functions $\\rho_{\\ell m}^{\\rm Num}$ through...
Temporal evolution of linear kinetic Alfvén waves in inhomogeneous plasmas and turbulence generation
Goyal, Ravinder; Sharma, R. P.
2016-07-01
The coronal ion heating in the Sun is primarily considered due to Alfvén wave dissipation. The Hinode data which has provided strong evidence for the presence of Alfvén waves in the corona and in coronal loops, has lead laboratory investigations and numerical simulations of Alfvén wave propagation and damping. The inhomogeneous plasmas with steep density gradients can be employed to study such phenomenon in relatively shorter systems. This article presents a model for the propagation of Kinetic Alfvén waves (KAWs) in inhomogeneous plasma when the inhomogeneity is in transverse and parallel directions relative to the background magnetic field. The semi-analytical technique and numerical simulations have been performed to study the KAW dynamics when plasma inhomogeneity is incorporated in the dynamics. The model equations are solved in order to study the localization of KAW and their magnetic power spectrum which indicates the direct transfer of energy from lower to higher wave numbers as well as frequencies. The inhomogeneity scale lengths in both directions may control the nature of fluctuations and localization of the waves and play a very important role in the turbulence generation and its level. We present a theoretical study of the localization of KAWs, variations in magnetic field amplitude in time, and variation in the frequency spectra arising from inhomogeneities. The relevance of the model to space and laboratory observations is discussed.
X. Liu
2013-01-01
Full Text Available We study the momentum deposition in the thermosphere from the dissipation of small amplitude gravity waves (GWs within a wave packet using a fully nonlinear two-dimensional compressible numerical model. The model solves the nonlinear propagation and dissipation of a GW packet from the stratosphere into the thermosphere with realistic molecular viscosity and thermal diffusivity for various Prandtl numbers. The numerical simulations are performed for GW packets with initial vertical wavelengths (λ_{z} ranging from 5 to 50 km. We show that λ_{z} decreases in time as a GW packet dissipates in the thermosphere, in agreement with the ray trace results of Vadas and Fritts (2005 (VF05. We also find good agreement for the peak height of the momentum flux (z_{diss} between our simulations and VF05 for GWs with initial λ_{z} ≤ 2π H in an isothermal, windless background, where H is the density scale height. We also confirm that z_{diss} increases with increasing Prandtl number. We include eddy diffusion in the model, and find that the momentum deposition occurs at lower altitudes and has two separate peaks for GW packets with small initial λ_{z}. We also simulate GW packets in a non-isothermal atmosphere. The net λ_{z} profile is a competition between its decrease from viscosity and its increase from the increasing background temperature. We find that the wave packet disperses more in the non-isothermal atmosphere, and causes changes to the momentum flux and λ_{z} spectra at both early and late times for GW packets with initial λ_{z} ≥ 10 km. These effects are caused by the increase in T in the thermosphere, and the decrease in T near the mesopause.
A laboratory search for plasma erosion by Alfven waves
Vincena, S.; Gekelman, W.; Pribyl, P.
2007-12-01
Obliquely propagating shear Alfven waves with transverse wavelengths on the order of the electron inertial length or even the ion gyro-radius are commonly observed in the earth's low-altitude auroral zones. These regions are also replete with observations of electron beams and transversely heated ions. A kinetic treatment of shear Alfven wave-particle interaction reveals how these waves can be responsible for some of the observed particle acceleration. The auroral plasma environment is further enriched by the presence of field-aligned depletions in plasma density, and it has been suggested* that the Alfven waves may, in fact, be the cause of the erosion of ionospheric density. In this laboratory experiment, shear waves will be launched using a variety of proven antennas, and also allowed to grow spontaneously as Drift-Alfven modes in seeded density depletions**. Detailed measurements of the wave magnetic fields in the perpendicular density gradient regions will be presented which demonstrate the generation of short perpendicular wave scales due to the perpendicular gradient in parallel wave phase speed. Miniature in-situ particle diagnostics will also be used to look for electron and ion acceleration. The waves will also be launched into an increasing region of background magnetic field in an attempt to model the ratios of Alfven speed to electron thermal speed, and density gradient scale length to electron inertial length appropriate to the earth's auroral zone. Preliminary results will be presented on the efficacy of shear Alfven waves to self-generate plasma density depletions, or deepen ambient density inhomogeneities. The experiments are conducted at UCLA's Basic Plasma Science Facility in the Large Plasma Device. *Chaston, et al., "Ionospheric erosion by Alfven Waves," JGR, V 111, A03206, 2006. **Penano, et al., "Drift-Alfven fluctuations associated with a narrow pressure striation," Phys. Plasmas, V 7, Issue 1, pp. 144-157 (2000).
Linear and Nonlinear MHD Wave Processes in Plasmas. Final Report
Tataronis, J. A.
2004-06-01
This program treats theoretically low frequency linear and nonlinear wave processes in magnetized plasmas. A primary objective has been to evaluate the effectiveness of MHD waves to heat plasma and drive current in toroidal configurations. The research covers the following topics: (1) the existence and properties of the MHD continua in plasma equilibria without spatial symmetry; (2) low frequency nonresonant current drive and nonlinear Alfven wave effects; and (3) nonlinear electron acceleration by rf and random plasma waves. Results have contributed to the fundamental knowledge base of MHD activity in symmetric and asymmetric toroidal plasmas. Among the accomplishments of this research effort, the following are highlighted: Identification of the MHD continuum mode singularities in toroidal geometry. Derivation of a third order ordinary differential equation that governs nonlinear current drive in the singular layers of the Alfvkn continuum modes in axisymmetric toroidal geometry. Bounded solutions of this ODE implies a net average current parallel to the toroidal equilibrium magnetic field. Discovery of a new unstable continuum of the linearized MHD equation in axially periodic circular plasma cylinders with shear and incompressibility. This continuum, which we named “accumulation continuum” and which is related to ballooning modes, arises as discrete unstable eigenfrequency accumulate on the imaginary frequency axis in the limit of large mode numbers. Development of techniques to control nonlinear electron acceleration through the action of multiple coherent and random plasmas waves. Two important elements of this program aye student participation and student training in plasma theory.
Effect of wave localization on plasma instabilities. Ph. D. Thesis
Levedahl, W.K.
1987-10-01
The Anderson model of wave localization in random media is involved to study the effect of solar wind density turbulence on plasma processes associated with the solar type III radio burst. ISEE-3 satellite data indicate that a possible model for the type III process is the parametric decay of Langmuir waves excited by solar flare electron streams into daughter electromagnetic and ion acoustic waves. The threshold for this instability, however, is much higher than observed Langmuir wave levels because of rapid wave convection of the transverse electromagnetic daughter wave in the case where the solar wind is assumed homogeneous. Langmuir and transverse waves near critical density satisfy the Ioffe-Reigel criteria for wave localization in the solar wind with observed density fluctuations -1 percent. Numerical simulations of wave propagation in random media confirm the localization length predictions of Escande and Souillard for stationary density fluctations. For mobile density fluctuations localized wave packets spread at the propagation velocity of the density fluctuations rather than the group velocity of the waves. Computer simulations using a linearized hybrid code show that an electron beam will excite localized Langmuir waves in a plasma with density turbulence. An action principle approach is used to develop a theory of non-linear wave processes when waves are localized. A theory of resonant particles diffusion by localized waves is developed to explain the saturation of the beam-plasma instability. It is argued that localization of electromagnetic waves will allow the instability threshold to be exceeded for the parametric decay discussed above.
Acceleration of injected electrons by the plasma beat wave accelerator
Joshi, C.; Clayton, C. E.; Marsh, K. A.; Dyson, A.; Everett, M.; Lal, A.; Leemans, W. P.; Williams, R.; Katsouleas, T.; Mori, W. B.
1992-07-01
In this paper we describe the recent work at UCLA on the acceleration of externally injected electrons by a relativistic plasma wave. A two frequency laser was used to excite a plasma wave over a narrow range of static gas pressures close to resonance. Electrons with energies up to our detection limit of 9.1 MeV were observed when 2.1 MeV electrons were injected in the plasma wave. No accelerated electrons above the detection threshold were observed when the laser was operated on a single frequency or when no electrons were injected. Experimental results are compared with theoretical predictions, and future prospects for the plasma beat wave accelerator are discussed.
Relativistic effects on the modulational instability of electron plasma waves in quantum plasma
Basudev Ghosh; Swarniv Chandra; Sailendra Nath Paul
2012-05-01
Relativistic effects on the linear and nonlinear properties of electron plasma waves are investigated using the one-dimensional quantum hydrodynamic (QHD) model for a twocomponent electron–ion dense quantum plasma. Using standard perturbation technique, a nonlinear Schrödinger equation (NLSE) containing both relativistic and quantum effects has been derived. This equation has been used to discuss the modulational instability of the wave. Through numerical calculations it is shown that relativistic effects signiﬁcantly change the linear dispersion character of the wave. Unlike quantum effects, relativistic effects are shown to reduce the instability growth rate of electron plasma waves.
Propagation of ion-acoustic waves in a dusty plasma with non-isothermal electrons
K K Mondal
2007-08-01
For an unmagnetised collisionless plasma consisting of warm ions, non-isothermal electrons and cold, massive and charged dust grains, the Sagdeev potential equation, considering both ion dynamics and dust dynamics has been derived. It has been observed that the Sagdeev potential () exists only for > 0 up to an upper limit ( ≃ 1.2). This implies the possibility of existence of compressive solitary wave in the plasma. Exhaustive numerics done for both the large-amplitude and small-amplitude ion-acoustic waves have revealed that various parameters, namely, ion temperature, non-isothermality of electrons, Mach numbers etc. have considerable impact on the amplitude as well as the width of the solitary waves. Dependence of soliton profiles on the ion temperature and the Mach number has also been graphically displayed. Moreover, incorporating dust-charge fluctuation and non-isothermality of electrons, a non-linear equation relating the grain surface potential to the electrostatic potential has been derived. It has been solved numerically and interdependence of the two potentials for various ion temperatures and orders of non-isothermality has been shown graphically.
Parameteric studies of nonlinear oblique magnetosonic waves in two-ion-species plasmas
Toida, Mieko; Kondo, Yuichi
2011-06-01
The study of the effects of ion composition on perpendicular magnetosonic waves in two-ion-species plasmas [M. Toida, H. Higashino, and Y. Ohsawa, J. Phys. Soc. Jpn. 76, 104052 (2007)] is extended to include oblique waves. First, the conditions necessary for KdV equations for low- and high-frequency modes to be valid are analytically obtained. The upper limit of the amplitude of the low-frequency-mode pulse is expressed as a function of the propagation angle θ, density ratio, and cyclotron frequency ratio of the two ion species. Next, with electromagnetic particle simulations, the nonlinear evolution of a long-wavelength low-frequency-mode disturbance is examined for various θs in two plasmas with different ion densities and cyclotron frequency ratios, and the theory for the low-frequency-mode pulse is confirmed. It is also shown that if the pulse amplitude exceeds the theoretical value of the upper limit of the amplitude, then shorter-wavelength low- and high-frequency-mode waves are generated.
Kouznetsov, Igor; Lotko, William
1995-01-01
The 'radial' transport of energy by internal ULF waves, stimulated by dayside magnetospheric boundary oscillations, is analyzed in the framework of one-fluid magnetohydrodynamics. (the term radial is used here to denote the direction orthogonal to geomagnetic flux surfaces.) The model for the inhomogeneous magnetospheric plasma and background magnetic field is axisymmetric and includes radial and parallel variations in the magnetic field, magnetic curvature, plasma density, and low but finite plasma pressure. The radial mode structure of the coupled fast and intermediate MHD waves is determined by numerical solution of the inhomogeneous wave equation; the parallel mode structure is characterized by a Wentzel-Kramer-Brillouin (WKB) approximation. Ionospheric dissipation is modeled by allowing the parallel wave number to be complex. For boudnary oscillations with frequencies in the range from 10 to 48 mHz, and using a dipole model for the background magnetic field, the combined effects of magnetic curvature and finite plasma pressure are shown to (1) enhance the amplitude of field line resonances by as much as a factor of 2 relative to values obtained in a cold plasma or box-model approximation for the dayside magnetosphere; (2) increase the energy flux delivered to a given resonance by a factor of 2-4; and (3) broaden the spectral width of the resonance by a factor of 2-3. The effects are attributed to the existence of an 'Alfven buoyancy oscillation,' which approaches the usual shear mode Alfven wave at resonance, but unlike the shear Alfven mode, it is dispersive at short perpendicular wavelengths. The form of dispersion is analogous to that of an internal atmospheric gravity wave, with the magnetic tension of the curved background field providing the restoring force and allowing radial propagation of the mode. For nominal dayside parameters, the propagation band of the Alfven buoyancy wave occurs between the location of its (field line) resonance and that of the
Transport of time-varying plasma currents by whistler wave packets
Stenzel, R. L.; Urrutia, J. M.; Rousculp, C.
1992-01-01
The relationship between pulsed currents and electromagnetic waves is examined in a regime characterized by electron MHD. Pulsed currents are generated by (1) collection/emission of charged particles by/from biased electrodes and (2) induction of currents by time-varying and moving magnetic fields. Pulsed currents are observed to propagate at the speed of whistler wave packets. Their field structure forms ropelike configurations which are electromagnetically force-free. Moving sources induce 'eddy' currents which excite waves and form Cerenkov-like whistler 'wings'. The radiation patterns of moving magnetic antennas and electrodynamic tethers are investigated. Nonlinear effects of large-amplitude, antenna-launched whistler pulses are observed. These involve a new modulational instability in which a channel of high conductivity which permits the wave/currents to penetrate deeply into a collisional plasma is formed.
Singh, S. V.; Devanandhan, S.; Lakhina, G. S.; Bharuthram, R.
2016-08-01
A theoretical investigation is carried out to study the obliquely propagating electron acoustic solitary waves having nonthermal hot electrons, cold and beam electrons, and ions in a magnetized plasma. We have employed reductive perturbation theory to derive the Korteweg-de-Vries-Zakharov-Kuznetsov (KdV-ZK) equation describing the nonlinear evolution of these waves. The two-dimensional plane wave solution of KdV-ZK equation is analyzed to study the effects of nonthermal and beam electrons on the characteristics of the solitons. Theoretical results predict negative potential solitary structures. We emphasize that the inclusion of finite temperature effects reduces the soliton amplitudes and the width of the solitons increases by an increase in the obliquity of the wave propagation. The numerical analysis is presented for the parameters corresponding to the observations of "burst a" event by Viking satellite on the auroral field lines.
Excitation of Chirping Whistler Waves in a Laboratory Plasma
Van Compernolle, B.; An, X.; Bortnik, J.; Thorne, R. M.; Gekelman, W. N.; Pribyl, P.
2015-12-01
Whistler mode chorus emissions with a characteristic frequency chirp are an important magnetospheric wave, responsible for the acceleration of outer radiation belt electrons to relativistic energies and also for the scattering loss of these electrons into the atmosphere. Here, we report on the first laboratory experiment where whistler waves exhibiting fast frequency chirping have been artificially produced using a beam of energetic electrons launched into a cold plasma. Frequency chirps are only observed for a narrow range of plasma and beam parameters, and show a strong dependence on beam density, plasma density and magnetic field gradient. Broadband whistler waves similar to magnetospheric hiss are also observed, and the parameter ranges for each emission are quantified. The research was funded by NSF/DOE Plasma Partnership program by grant DE-SC0010578. Work was done at the Basic Plasma Science Facility (BAPSF) also funded by NSF/DOE.
Electron-acoustic rogue waves in a plasma with Tribeche–Tsallis–Cairns distributed electrons
Merriche, Abderrzak [Faculty of Physics, Theoretical Physics Laboratory (TPL), Plasma Physics Group (PPG), University of Bab-Ezzouar, USTHB, B. P. 32, El Alia, Algiers 16111 (Algeria); Tribeche, Mouloud, E-mail: mouloudtribeche@yahoo.fr [Faculty of Physics, Theoretical Physics Laboratory (TPL), Plasma Physics Group (PPG), University of Bab-Ezzouar, USTHB, B. P. 32, El Alia, Algiers 16111 (Algeria); Algerian Academy of Sciences and Technologies, Algiers (Algeria)
2017-01-15
The problem of electron-acoustic (EA) rogue waves in a plasma consisting of fluid cold electrons, nonthermal nonextensive electrons and stationary ions, is addressed. A standard multiple scale method has been carried out to derive a nonlinear Schrödinger-like equation. The coefficients of dispersion and nonlinearity depend on the nonextensive and nonthermal parameters. The EA wave stability is analyzed. Interestingly, it is found that the wave number threshold, above which the EA wave modulational instability (MI) sets in, increases as the nonextensive parameter increases. As the nonthermal character of the electrons increases, the MI occurs at large wavelength. Moreover, it is shown that as the nonextensive parameter increases, the EA rogue wave pulse grows while its width is narrowed. The amplitude of the EA rogue wave decreases with an increase of the number of energetic electrons. In the absence of nonthermal electrons, the nonextensive effects are more perceptible and more noticeable. In view of the crucial importance of rogue waves, our results can contribute to the understanding of localized electrostatic envelope excitations and underlying physical processes, that may occur in space as well as in laboratory plasmas.
Kinetic simulations of ladder climbing by electron plasma waves
Hara, Kentaro; Barth, Ido; Kaminski, Erez; Dodin, I. Y.; Fisch, N. J.
2017-05-01
The energy of plasma waves can be moved up and down the spectrum using chirped modulations of plasma parameters, which can be driven by external fields. Depending on whether the wave spectrum is discrete (bounded plasma) or continuous (boundless plasma), this phenomenon is called ladder climbing (LC) or autoresonant acceleration of plasmons. It was first proposed by Barth et al. [Phys. Rev. Lett. 115, 075001 (2015), 10.1103/PhysRevLett.115.075001] based on a linear fluid model. In this paper, LC of electron plasma waves is investigated using fully nonlinear Vlasov-Poisson simulations of collisionless bounded plasma. It is shown that, in agreement with the basic theory, plasmons survive substantial transformations of the spectrum and are destroyed only when their wave numbers become large enough to trigger Landau damping. Since nonlinear effects decrease the damping rate, LC is even more efficient when practiced on structures like quasiperiodic Bernstein-Greene-Kruskal (BGK) waves rather than on Langmuir waves per se.
Alfven waves in a partially ionized two-fluid plasma
Soler, R; Ballester, J L; Terradas, J
2013-01-01
Alfv\\'en waves are a particular class of magnetohydrodynamic waves relevant in many astrophysical and laboratory plasmas. In partially ionized plasmas the dynamics of Alfv\\'en waves is affected by the interaction between ionized and neutral species. Here we study Alfv\\'en waves in a partially ionized plasma from the theoretical point of view using the two-fluid description. We consider that the plasma is composed of an ion-electron fluid and a neutral fluid, which interact by means of particle collisions. To keep our investigation as general as possible we take the neutral-ion collision frequency and the ionization degree as free parameters. First, we perform a normal mode analysis. We find the modification due to neutral-ion collisions of the wave frequencies and study the temporal and spatial attenuation of the waves. In addition, we discuss the presence of cut-off values of the wavelength that constrain the existence of oscillatory standing waves in weakly ionized plasmas. Later, we go beyond the normal mo...
Numerical modelling of overtaking collisions of dust acoustic waves in plasmas
Gao, Dong-Ning; Zhang, Heng; Zhang, Jie; Li, Zhong-Zheng; Duan, Wen-Shan
2016-10-01
The overtaking collision between two single and unidirectional dust acoustic waves in dusty plasmas consisting of Boltzmann electrons and ions, and negative dust grains has been investigated by PIC simulation method. The well-known physical phenomenon is that the larger soliton moves faster, approaches the smaller one and after the overtaking collision both resume their original shape and speed with different phase shifts. The merging amplitude of two solitons and phase shifts of solitons after collision are given. These PIC results are compared with the overtaking collision of two-soliton solution (TSS) of KdV equaiton obtained by Hirota bilinear method. Comparisons between two indicates that if the amplitude of fast soliton is large enough or the amplitude of slow soliton is small enough, the simulation results are consistent with the interaction of Hirota results.
Brunner, S. [Centre de Recherches en Physique des Plasmas, Association Euratom-Confédération Suisse, Ecole Polytechnique Fédérale de Lausanne, Lausanne, (Switzerland); Berger, R. L. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Cohen, B. I. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Hausammann, L. [Centre de Recherches en Physique des Plasmas, Association Euratom-Confédération Suisse, Ecole Polytechnique Fédérale de Lausanne, Lausanne, (Switzerland); Valeo, E. J. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
2014-10-01
Kinetic Vlasov simulations of one-dimensional finite amplitude Electron Plasma Waves are performed in a multi-wavelength long system. A systematic study of the most unstable linear sideband mode, in particular its growth rate γ and quasi- wavenumber δk, is carried out by scanning the amplitude and wavenumber of the initial wave. Simulation results are successfully compared against numerical and analytical solutions to the reduced model by Kruer et al. [Phys. Rev. Lett. 23, 838 (1969)] for the Trapped Particle Instability (TPI). A model recently suggested by Dodin et al. [Phys. Rev. Lett. 110, 215006 (2013)], which in addition to the TPI accounts for the so-called Negative Mass Instability because of a more detailed representation of the trapped particle dynamics, is also studied and compared with simulations.
Plasma-ﬁlled rippled wall rectangular backward wave oscillator driven by sheet electron beam
A Hadap; J Mondal; K C Mittal; K P Maheshwari
2011-03-01
Performance of the backward wave oscillator (BWO) is greatly enhanced with the introduction of plasma. Linear theory of the dispersion relation and the growth rate have been derived and analysed numerically for plasma-ﬁlled rippled wall rectangular waveguide driven by sheet electron beam. To see the effect of plasma on the TM01 cold wave structure mode and on the generated frequency, the parameters used are: relativistic factor = 1.5 (i.e. / = 0.741), average waveguide height 0 = 1.445 cm, axial corrugation period 0 = 1.67 cm, and corrugation amplitude = 0.225 cm. The plasma density is varied from zero to 2 × 1012 cm-3. The presence of plasma tends to raise the TM01 mode cut-off frequency (14 GH at 2 × 1012 cm-3 plasma density) relative to the vacuum cut-off frequency (5 GH) which also causes a decrease in the group velocity everywhere, resulting in a ﬂattening of the dispersion relation. With the introduction of plasma, an enhancement in absolute instability was observed.
Scattering of radio frequency waves by turbulence in fusion plasmas
Ram, Abhay K.
2016-10-01
In tokamak fusion plasmas, coherent fluctuations in the form of blobs or filaments and incoherent fluctuations due to turbulence are routinely observed in the scrape-off layer. Radio frequency (RF) electromagnetic waves, excited by antenna structures placed near the wall of a tokamak, have to propagate through the scrape-off layer before reaching the core of the plasma. While the effect of fluctuations on RF waves has not been quantified experimentally, there are telltale signs, arising from differences between results from simulations and from experiments, that fluctuations can modify the spectrum of RF waves. Any effect on RF waves in the scrape-off layer can have important experimental consequences. For example, electron cyclotron waves are expected to stabilize the deleterious neoclassical tearing mode (NTM) in ITER. Spectral and polarization changes due to scattering will modify the spatial location and profile of the current driven by the RF waves, thereby affecting the control of NTMs. Pioneering theoretical studies and complementary computer simulations have been pursued to elucidate the impact of fluctuations on RF waves. From the full complement of Maxwell's equations for cold, magnetized plasmas, it is shown that the Poynting flux in the wake of filaments develops spatial structure due to diffraction and shadowing. The uniformity of power flow into the plasma is affected by side-scattering, modifications to the wave spectrum, and coupling to plasma waves other than the incident RF wave. The Snell's law and the Fresnel equations have been reformulated within the context of magnetized plasmas. They are distinctly different from their counterparts in scalar dielectric media, and reveal new and important physical insight into the scattering of RF waves. The Snell's law and Fresnel equations are the basis for the Kirchhoff approximation necessary to determine properties of the scattered waves. Furthermore, this theory is also relevant for studying back
Electromagnetic drift waves dispersion for arbitrarily collisional plasmas
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.
Surface Waves in the paritally ionized solar plasma slab
Pandey, B P
2013-01-01
The properties of surface waves in the partially ionized, incompressible magnetized plasma slab are investigated in the present work. The waves are affected by the non ideal MHD effects which causes the finite drift of the magnetic field in the medium. When the finite drift of the magnetic field is ignored, the characteristics of the wave propagation in the partially ionized plasma fluid is similar to the ideal MHD except now the propagation properties depend on the fractional ionization of the medium. In the presence of Hall diffusion, the propagation of the sausage and kink surface waves depends on the level of fractional ionization of the medium. When both the Hall and Pedersen diffusion are present in the medium, the waves undergoes damping. For typical solar parameters, waves may damp over few minutes.
Electromagnetic ion cyclotron waves in the plasma depletion layer
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.
Dust-acoustic solitary waves in a magnetized dusty plasma with nonthermal electrons and trapped ions
Misra, A. P.; Wang, Yunliang
2015-05-01
The nonlinear propagation of electrostatic dust-acoustic (DA) waves in a magnetized dusty plasma consisting of negatively charged mobile dusts, nonthermal fast electrons and trapped ions with vortex-like distribution is studied. Using the reductive perturbation technique, a Korteweg-de Vries (KdV)-like equation is derived which governs the dynamics of the small-amplitude solitary waves in a magnetized dusty nonthermal plasma. It is found that due to the dust thermal pressure, there exists a critical value (βc) of the nonthermal parameter β (>1), denoting the percentage of energetic electrons, below which the DA solitary waves cease to propagate. The soliton solution (traveling wave) of the KdV-like equation is obtained, and is shown to be only of the rarefactive type. The properties of the solitons are analyzed numerically with the system parameters. It is also seen that the effect of the static magnetic field (which only modifies the soliton width) becomes significant when the dust gyrofrequency is smaller than one-tenth of the dust plasma frequency. Furthermore, the amplitude of the soliton is found to increase (decrease) when the ratio of the free to trapped ion temperatures (σ) is positive (negative). The effects of the system parameters including the obliqueness of propagation (lz) and σ on the dynamics of the DA solitons are also discussed numerically, and it is found that the soliton structures can withstand perturbations and turbulence during a considerable time. The results should be useful for understanding the nonlinear propagation of DA solitary waves in laboratory and space plasmas (e.g., Earth's magnetosphere, auroral region, heliospheric environments, etc.).
Nonlinear Langmuir Wave Modulation in Weakly Magnetized Plasmas
Dysthe, K. B.; Pécseli, Hans
1978-01-01
influence on the modulation stability of plane Langmuir waves. As in the unmagnetized case, kinetic results were found to deviate considerably from those obtained by using a fluid description for the ion dynamics. With particular attention to ionospheric phenomena, the effect is included of the spatially...... varying electron heating in the amplitude modulated Langmuir wave. For modulations travelling almost perpendicular to the magnetic field, this effect has a profound influence on a modulational instability...
Tsuda, M.; Ono, K.; Tsuchihashi, M.; Hanazaki, M.; Komemura, T. [Mitsubishi Electric Corp., Tokyo (Japan)
1998-11-01
A new-type microwave plasma source has been developed for materials processing. The plasma reactor employed a launcher of azimuthally symmetric surface waves at a frequency of 2.45 GHz and also magnetic multicusp fields around the reactor chamber walls. This configuration yielded high-density (Ne {>=} 10{sup 11}cm{sup -3}) plasmas sustained by surface waves even at low gas pressures below 10 m Torr, following easy plasma ignition by electron cyclotron resonance (ECR) discharges. Electrical and optical diagnostics were made to obtain the plasma properties in Ar. It was shown that a transition from ECR excited to surface-wave excited plasmas occurs under conditions where the plasma electron density exceeds a critical value of Ne-1 times 10{sup 11}cm{sup -3}. 21 refs., 14 figs.
Polar Plasma Wave Investigation Data Analysis in the Extended Mission
Gurnett, Donald A.
2004-01-01
The low latitude boundary layer (LLBL) is a region where solar wind momentum and energy is transferred to the magnetosphere. Enhanced "broadband" electric plasma waves from less than 5 Hz to 10(exp 5) Hz and magnetic waves from less than 5 Hz to the electron cyclotron frequency are characteristic of the LLBL. Analyses of Polar plasma waves show that these "broadband" waves are actually discrete electrostatic and electromagnetic modes as well as solitary bipolar pulses (electron holes). It is noted that all wave modes can be generated by approx. 100 eV to approx. 10 keV auroral electrons and protons. We will review wave-particle interactions, with focus on cross-diffusion rates and the contributions of such interactions toward the formation of the boundary layer. In summary, we will present a scenario where the global solar wind-magnetosphere interaction is responsible for the auroral zone particle beams, and hence for the generation of plasma waves and the formation of the boundary layer. It is speculated that all planetary magnetospheres will have boundary layers and they will be characterized by similar currents and plasma wave modes.
T wave amplitude in lead aVR as a novel diagnostic marker for cardiac sarcoidosis.
Tanaka, Yoshihiro; Konno, Tetsuo; Yoshida, Shohei; Tsuda, Toyonobu; Sakata, Kenji; Furusho, Hiroshi; Takamura, Masayuki; Yoshimura, Kenichi; Yamagishi, Masakazu; Hayashi, Kenshi
2017-03-01
It is vital to identify cardiac involvement (CI) in patients with sarcoidosis as the condition could initially lead to sudden cardiac death. Although the T wave amplitude in lead aVR (TWAaVR) is reportedly associated with adverse cardiac events in various cardiovascular diseases, only scarce data are available concerning the utility of lead aVR in identifying CI in patients with sarcoidosis. We retrospectively investigated the diagnostic values of TWAaVR in patients with sarcoidosis in comparison with conventional electrocardiography parameters such as bundle branch block (BBB). From January 2006 to December 2014, 93 consecutive patients with sarcoidosis were enrolled (mean age, 55.7 ± 15.7 years; male, 31 %; cardiac involvement, n = 26). TWAaVR showed the greatest sensitivity (39 %) and specificity (92 %) in distinguishing between sarcoidosis patients with and without CI, at a cutoff value of -0.08 mV. The diagnostic value of BBB for cardiac involvement was significantly improved when combined with TWAaVR (sensitivity: 61-94 %, specificity: 97-89 %, area under the curve: 0.79-0.92, p = 0.018). Multivariate logistic regression analysis indicated that TWAaVR and BBB were independent electrocardiography parameters associated with CI. In summary, we observed that sarcoidosis patients exhibiting a high TWAaVR were likely to have CI. Thus, the application of a combination of BBB with TWAaVR may be useful when screening for CI in sarcoidosis patients.
Feinberg, I; Thode, H C; Chugani, H T; March, J D
1990-01-23
We analyzed the available ontogenetic data (birth to 30 years of age) for: amplitude of delta EEG (DA) waves during sleep; cortical metabolic rate (CMR) measured with positron emission tomography; and synaptic density (SD) in frontal cortex. Each is at the adult level at birth, increases to about twice this level by 3 years of age, and then gradually falls back to the adult level over the next two decades. Statistical analyses revealed that individual gamma distribution models fit each data set as well as did the best ad hoc polynomial. A test of whether a single gamma distribution model could describe all three data sets gave good results for DA and CMR but the fit was unsatisfactory for SD. However, because so few data were available for SD, this test was not conclusive. We proposed the following model to account for these changes. First, cortical neurons are stimulated by birth to enter a proliferative state (PS) that creates many connections. Next, as a result of interactions in the PS, neurons are triggered into a transient organizational state (OS) in which they make enduring connections. The OS has a finite duration (minutes to years), and is characterized by high rates of information-processing and metabolism. Levels of CMR, SD and DA, therefore, are proportional to the number of neurons in the OS at any time. Thus, the cortex after birth duplicates, over a vastly greater time scale, the overproduction and regression of neural elements that occurs repeatedly in embryonic development. Finally, we discussed the implications of post-natal brain changes for normal and abnormal brain function. Mental disorders that have their onset after puberty (notably schizophrenia and manic-depressive psychoses) might be caused by errors in these late maturational processes. In addition to age of onset, this neurodevelopmental hypothesis might explain several other puzzling features of these subtle disorders.
Guede, Jose Ricardo Abalde
1995-11-01
The aim of this work is to study the nonlinear dynamics of Langmuir and electromagnetic waves in space plasmas. Firstly, the generalized Zakharov equations are derived which are used to study the hybrid parametric instability involving the generation of daughter Langmuir, electromagnetic and ion-acoustic waves induced by two counter-propagating Langmuir pump waves with different amplitudes based on a coupled dispersion relation. Secondly, starting from the generalized Zakharov equations the linear and nonlinear coupled mode theories of three-wave and four-wave parametric interactions are developed, respectively. In three-waves processes, a Langmuir wave decays into another Langmuir wave and an ion-acoustic wave (electrostatic parametric decay) or into an electromagnetic wave and an ion-acoustic wave (electromagnetic parametric decay). In four-wave (modulational) processes, the interaction involves two wave triplets: in the decay triplet a pump wave couples with a low-frequency wave to generate a Stokes wave, and in the fusion triplets: in the decay triplet a pump wave couples with a low-frequency wave to generate a Stokes wave, and in the fusion triplet the coupling of a pump wave with a low-frequency wave generate an anti-Stokes wave. These modulational processes are convective and resonant processes wherein the low-frequency modes are Eigenmodes of plasma and are known as the stimulated modulational processes. Four such processes are investigated in this thesis: two with Langmuir pump waves (electrostatic and hybrid stimulated modulation processes) and the other two with electromagnetic pump waves (stimulated modulation Brillouin scattering and electromagnetic stimulated modulation process). Applications of the theoretical results in space plasmas are discussed. In particular, it is shown that the electrostatic and electromagnetic parametric decay processes of Langmuir waves can model the generation and modulation of radio emissions and Langmuir waves in the
Surface waves on a quantum plasma half-space
Lázár, M; Smolyakov, A
2007-01-01
Surface modes are coupled electromagnetic/electrostatic excitations of free electrons near the vacuum-plasma interface and can be excited on a sufficiently dense plasma half-space. They propagate along the surface plane and decay in either sides of the boundary. In such dense plasma models, which are of interest in electronic signal transmission or in some astrophysical applications, the dynamics of the electrons is certainly affected by the quantum effects. Thus, the dispersion relation for the surface wave on a quantum electron plasma half-space is derived by employing the quantum hydrodynamical (QHD) and Maxwell-Poison equations. The QHD include quantum forces involving the Fermi electron temperature and the quantum Bohm potential. It is found that, at room temperature, the quantum effects are mainly relevant for the electrostatic surface plasma waves in a dense gold metallic plasma.
Held, Magnus; Wiesenberger, M.; Madsen, Jens
2016-01-01
Thermal effects on the perpendicular convection of seeded pressure blobs in the scrape-off layer of magnetised fusion plasmas are investigated. Our numerical study is based on a four field full-F gyrofluid model, which entails the consistent description of high fluctuation amplitudes and dynamic...
Chatterjee, D
2015-01-01
The nonlinear theory of amplitude modulation of electrostatic wave envelopes in a collisionless electron-positron (EP) pair plasma is studied by using a set of Vlasov-Poisson equations in the context of Tsallis' $q$-nonextensive statistics. In particular, the previous linear theory of Langmuir oscillations in EP plasmas [Phys. Rev. E {\\bf87}, 053112 (2013)] is rectified and modified. Applying the multiple scale technique (MST), it is shown that the evolution of electrostatic wave envelopes is governed by a nonlinear Schr{\\"o}dinger (NLS) equation with a nonlocal nonlinear term $\\propto {\\cal{P}}\\int|\\phi(\\xi',\\tau)|^2d\\xi'\\phi/(\\xi-\\xi') $ [where ${\\cal P}$ denotes the Cauchy principal value, $\\phi$ is the small-amplitude electrostatic (complex) potential, and $\\xi$ and $\\tau$ are the stretched coordinates in MST] which appears due to the wave-particle resonance. It is found that a subregion $1/3wave frequency can turn over with the gro...
Susan Abadi
2016-09-01
Full Text Available Speech delay with an unknown cause is a problem among children. This diagnosis is the last differential diagnosis after observing normal findings in routine hearing tests. The present study was undertaken to determine whether auditory brainstem responses to click stimuli are different between normally developing children and children suffering from delayed speech with unknown causes. In this cross-sectional study, we compared click auditory brainstem responses between 261 children who were clinically diagnosed with delayed speech with unknown causes based on normal routine auditory test findings and neurological examinations and had >12 months of speech delay (case group and 261 age- and sex-matched normally developing children (control group. Our results indicated that the case group exhibited significantly higher wave amplitude responses to click stimuli (waves I, III, and V than did the control group (P=0.001. These amplitudes were significantly reduced after 1 year (P=0.001; however, they were still significantly higher than those of the control group (P=0.001. The significant differences were seen regardless of the age and the sex of the participants. There were no statistically significant differences between the 2 groups considering the latency of waves I, III, and V. In conclusion, the higher amplitudes of waves I, III, and V, which were observed in the auditory brainstem responses to click stimuli among the patients with speech delay with unknown causes, might be used as a diagnostic tool to track patients’ improvement after treatment.
Surface plasma waves over bismuth–vacuum interface
Ashim P Jain; J Parashar
2003-09-01
A surface plasma wave (SPW) over bismuth–vacuum interface has a signature of mass anisotropy of free electrons. For SPW propagation along the trigonal axis there is no birefringence. The frequency cutoff of SPW cutoff=$_{p}/\\sqrt{2(_{L}+)}$ lies in the far infrared region and can be accessed using free electron laser. The damping rate of waves at low temperatures is low. The surface plasma wave may be excited by an electron beam of current ∼ 100 mA propagating parallel to the interface in its close proximity.
M. G. Hafez
2016-01-01
Full Text Available Two-dimensional three-component plasma system consisting of nonextensive electrons, positrons, and relativistic thermal ions is considered. The well-known Kadomtsev-Petviashvili-Burgers and Kadomtsev-Petviashvili equations are derived to study the basic characteristics of small but finite amplitude ion acoustic waves of the plasmas by using the reductive perturbation method. The influences of positron concentration, electron-positron and ion-electron temperature ratios, strength of electron and positrons nonextensivity, and relativistic streaming factor on the propagation of ion acoustic waves in the plasmas are investigated. It is revealed that the electrostatic compressive and rarefactive ion acoustic waves are obtained for superthermal electrons and positrons, but only compressive ion acoustic waves are found and the potential profiles become steeper in case of subthermal positrons and electrons.
Shukla, P K; Eliasson, B
2007-08-31
We consider nonlinear interactions between intense circularly polarized electromagnetic (CPEM) waves and electron plasma oscillations (EPOs) in a dense quantum plasma, taking into account the electron density response in the presence of the relativistic ponderomotive force and mass increase in the CPEM wave fields. The dynamics of the CPEM waves and EPOs is governed by the two coupled nonlinear Schrödinger equations and Poisson's equation. The nonlinear equations admit the modulational instability of an intense CPEM pump wave against EPOs, leading to the formation and trapping of localized CPEM wave pipes in the electron density hole that is associated with a positive potential distribution in our dense plasma. The relevance of our investigation to the next generation intense laser-solid density plasma interaction experiments is discussed.
Instability wave control in turbulent jet by plasma actuators
Kopiev, V. F.; Akishev, Y. S.; Belyaev, I. V.; Berezhetskaya, N. K.; Bityurin, V. A.; Faranosov, G. A.; Grushin, M. E.; Klimov, A. I.; Kopiev, V. A.; Kossyi, I. A.; Moralev, I. A.; Ostrikov, N. N.; Taktakishvili, M. I.; Trushkin, N. I.; Zaytsev, M. Yu
2014-12-01
Instability waves in the shear layer of turbulent jets are known to be a significant source of jet noise, which makes their suppression important for the aviation industry. In this study we apply plasma actuators in order to control instability waves in the shear layer of a turbulent air jet at atmospheric pressure. Three types of plasma actuators are studied: high-frequency dielectric barrier discharge, slipping surface discharge, and surface barrier corona discharge. Particle image velocimetry measurements of the shear layer demonstrate that the plasma actuators have control authority over instability waves and effectively suppress the instability waves artificially generated in the shear layer. It makes these actuators promising for application in active control systems for jet noise mitigation.
Eulerian simulations of collisional effects on electrostatic plasma waves
Pezzi, Oreste; Perrone, Denise; Veltri, Pierluigi
2013-01-01
The problem of collisions in a plasma is a wide subject with a huge historical literature. In fact, the description of realistic plasmas is a tough problem to attach, both from the theoretical and the numerical point of view, and which requires in general to approximate the original collisional Landau integral by simplified differential operators in reduced dimensionality. In this paper, a Eulerian time-splitting algorithm for the study of the propagation of electrostatic waves in collisional plasmas is presented. Collisions are modeled through one-dimensional operators of the Fokker-Planck type, both in linear and nonlinear form. The accuracy of the numerical code is discussed by comparing the numerical results to the analytical predictions obtained in some limit cases when trying to evaluate the effects of collisions in the phenomenon of wave plasma echo and collisional dissipation of Bernstein-Greene-Kruskal waves. Particular attention is devoted to the study of the nonlinear Dougherty collisional operator...
Surface waves in the magnetized, collisional dusty plasmas
Pandey, B. P. [Department of Physics, Astronomy and Research Centre for Astronomy, Astrophysics and Astrophotonics, Macquarie University, Sydney NSW 2109 (Australia); Vladimirov, S. V. [School of Physics, The University of Sydney, Sydney NSW 2006 (Australia); Faculty of Engineering, Yokohama National University, Yokohama 240-8501 (Japan); Metamaterials Laboratory, National Research University of Information Technology, Mechanics, and Optics, St. Petersburg 199034 (Russian Federation); Ishihara, O. [Faculty of Engineering, Yokohama National University, Yokohama 240-8501 (Japan)
2013-10-15
The properties of the low frequency surface waves in inhomogeneous, magnetized collisional complex dusty plasma are investigated in this work. The inhomogeneity is modelled by the two distinct regions of the dusty medium with different dust densities. The external magnetic field is assumed to be oriented along the interface dividing the two medium. It is shown that the collisional momentum exchange that is responsible for the relative drift between the plasma particles affects the propagation of the surface waves in the complex plasma via the Hall drift of the magnetic fluctuations. The propagation properties of the sausage and kink waves depend not only on the grain charge and size distribution but also on the ambient plasma thermal conditions.
O Rahman; A A Mamun
2013-06-01
A theoretical investigation of dust-acoustic solitary waves in three-component unmagnetized dusty plasma consisting of trapped electrons, Maxwellian ions, and arbitrarily charged cold mobile dust was done. It has been found that, owing to the departure from the Maxwellian electron distribution to a vortex-like one, the dynamics of small but finite amplitude dust-acoustic (DA) waves is governed by a nonlinear equation of modified Korteweg–de Vries (mKdV) type (instead of KdV). The reductive perturbation method was employed to study the basic features (amplitude, width, speed, etc.) of DA solitary waves which are significantly modified by the presence of trapped electrons. The implications of our results in space and laboratory plasmas are briefly discussed.
Low-Frequency Waves in Cold Three-Component Plasmas
Fu, Qiang; Tang, Ying; Zhao, Jinsong; Lu, Jianyong
2016-09-01
The dispersion relation and electromagnetic polarization of the plasma waves are comprehensively studied in cold electron, proton, and heavy charged particle plasmas. Three modes are classified as the fast, intermediate, and slow mode waves according to different phase velocities. When plasmas contain positively-charged particles, the fast and intermediate modes can interact at the small propagating angles, whereas the two modes are separate at the large propagating angles. The near-parallel intermediate and slow waves experience the linear polarization, circular polarization, and linear polarization again, with the increasing wave number. The wave number regime corresponding to the above circular polarization shrinks as the propagating angle increases. Moreover, the fast and intermediate modes cause the reverse change of the electromagnetic polarization at the special wave number. While the heavy particles carry the negative charges, the dispersion relations of the fast and intermediate modes are always separate, being independent of the propagating angles. Furthermore, this study gives new expressions of the three resonance frequencies corresponding to the highly-oblique propagation waves in the general three-component plasmas, and shows the dependence of the resonance frequencies on the propagating angle, the concentration of the heavy particle, and the mass ratio among different kinds of particles. supported by National Natural Science Foundation of China (Nos. 11303099, 41531071 and 41574158), and the Youth Innovation Promotion Association CAS
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.
Vlasov simulations of electron-ion collision effects on damping of electron plasma waves
Banks, J. W., E-mail: banksj3@rpi.edu [Rensselaer Polytechnic Institute, Department of Mathematical Sciences, Troy, New York 12180 (United States); Brunner, S.; Tran, T. M. [Ecole Polytechnique Fédérale de Lausanne (EPFL), Swiss Plasma Center (SPC), CH-1015 Lausanne (Switzerland); Berger, R. L. [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551 (United States)
2016-03-15
Collisional effects can play an essential role in the dynamics of plasma waves by setting a minimum damping rate and by interfering with wave-particle resonances. Kinetic simulations of the effects of electron-ion pitch angle scattering on Electron Plasma Waves (EPWs) are presented here. In particular, the effects of such collisions on the frequency and damping of small-amplitude EPWs for a range of collision rates and wave phase velocities are computed and compared with theory. Both the Vlasov simulations and linear kinetic theory find the direct contribution of electron-ion collisions to wave damping significantly reduced from that obtained through linearized fluid theory. To our knowledge, this simple result has not been published before. Simulations have been carried out using a grid-based (Vlasov) approach, based on a high-order conservative finite difference method for discretizing the Fokker-Planck equation describing the evolution of the electron distribution function. Details of the implementation of the collision operator within this framework are presented. Such a grid-based approach, which is not subject to numerical noise, is of particular interest for the accurate measurements of the wave damping rates.
Ion-acoustic solitary waves in ion-beam plasma with multiple-electron-temperatures
Karmakar, B.; Das, G.C.; Singh, Kh.I.
1988-08-01
The solitary wave solution has been studied in an ion-beam plasma with multiple-electron-temperatures stemmed through the derivation of a modified Korteweg-de Vries (KdV) equation. The evolution of solitons shows that the existence and the behaviour depend effectively on the ion-beam as well as on the multiple-electron-temperatures. It has been shown that the solitons might be large amplitude waves with the addition of a small percentage of ion-beam concentration or by the increase of electron-temperatures. The present investigators believe and conclude that the solitons should also show experimentally these fascinating properties but one has to be careful about the range of the physical parameters in ion-beam plasma.
Waves generated in the vicinity of an argon plasma gun in the ionosphere
Cahill, L. J., Jr.; Arnoldy, R. L.; Lysak, R. L.; Peria, W.; Lynch, K. A.
1993-01-01
Wave and particle observations were made in the close vicinity of an argon plasma gun carned to over 600 km altitude on a sounding rocket. The gun was carned on a subpayload, separated from the main payload early in the flight. Twelve-second argon ion ejections were energized alternately with a peak energy of 100 or 200 eV. They produced waves, with multiple harmonics, in the range of ion cyclotron waves, 10 to 1000 Hz at rocket altitudes. Many of these waves could not be identified as corresponding to the cyclotron frequencies of any of the ions, argon or ambient, known to be present. In addition, the wave frequencies were observed to rise and fall and to change abruptly during a 12-s gun operation. The wave amplitudes, near a few hundred Hertz, were of the order of O. 1 V/m. Some of the waves may be ion-ion hybrid waves. Changes in ion populations were observed at the main payload and at the subpayload during gun operations. A gun-related, field-aligned, electron population also appeared.
Damping of Slow Magnetoacoustic Waves in an Inhomogeneous Coronal Plasma
Nagendra Kumar; Pradeep Kumar; Shiv Singh; Anil Kumar
2008-03-01
We study the propagation and dissipation of slow magnetoacoustic waves in an inhomogeneous viscous coronal loop plasma permeated by uniform magnetic field. Only viscosity and thermal conductivity are taken into account as dissipative processes in the coronal loop. The damping length of slow-mode waves exhibit varying behaviour depending upon the physical parameters of the loop in an active region AR8270 observed by TRACE. The wave energy flux associated with slow magnetoacoustic waves turns out to be of the order of 106 erg cm-2 s-1 which is high enough to replace the energy lost through optically thin coronal emission and the thermal conduction belowto the transition region. It is also found that only those slow-mode waves which have periods more than 240 s provide the required heating rate to balance the energy losses in the solar corona. Our calculated wave periods for slow-mode waves nearly match with the oscillation periods of loop observed by TRACE.
Wave-particle and wave-wave interactions in hot plasmas: a French historical point of view
Laval, Guy; Pesme, Denis; Adam, Jean-Claude
2016-11-01
The first researches on nuclear fusion for energy applications marked the entrance of hot plasmas into the laboratory. It became necessary to understand the behavior of such plasmas and to learn how to manipulate them. Theoreticians and experimentalists, building on the foundations of empirical laws, had to construct this new plasma physics from first principles and to explain the results of more and more complicated experiments. Along this line, two important topics emerged: wave-particle and wave-wave interactions. Here, their history is recalled as it has been lived by a French team from the end of the sixties to the beginning of the twenty-first century.
Terahertz generation by beating two Langmuir waves in a warm and collisional plasma
Zhang, Xiao-Bo; Qiao, Xin; Cheng, Li-Hong; Tang, Rong-An; Zhang, Ai-Xia; Xue, Ju-Kui, E-mail: xuejk@nwnu.edu.cn [Key Laboratory of Atomic & Molecular Physics and Functional Materials of Gansu Province, College of Physics and Electronics Engineering, Northwest Normal University, Lanzhou 730070 (China)
2015-09-15
Terahertz (THz) radiation generated by beating of two Langmuir waves in a warm and collisional plasma is discussed theoretically. The critical angle between the two Langmuir waves and the critical wave-length (wave vector) of Langmuir waves for generating THz radiation are obtained analytically. Furthermore, the maximum radiation energy is obtained. We find that the critical angle, the critical wave-length, and the generated radiation energy strongly depend on plasma temperature and wave-length of the Langmuir waves. That is, the THz radiation generated by beating of two Langmuir waves in a warm and collisional plasma can be controlled by adjusting the plasma temperature and the Langmuir wave-length.
Gao, Fei; Liu, Yu-xin
2016-01-01
We propose a new numerical method to compute parton distribution amplitude(PDA) from the Euclidean Bethe-Salpeter wave function. The essential step is to extract the weight function in the Nakanishi representation of the Bethe-Salpeter wave function in Euclidean space, which is an ill-posed inversion problem, via the maximum entropy method(MEM). The Nakanishi weight function as well as the corresponding light-front PDA can be well determined. We confirm the previous works on PDA computation therein the different method has been performed.
Hafez, M. G.; Roy, N. C.; Talukder, M. R.; Hossain Ali, M.
2016-08-01
The characteristics of the nonlinear oblique propagation of ion acoustic solitary waves in unmagnetized plasmas consisting of Boltzmann positrons, trapped electrons and ions are investigated. The modified Kadomtsev-Petviashivili ( m K P ) equation is derived employing the reductive perturbation technique. The parametric effects on phase velocity, Sagdeev potential, amplitude and width of solitons, and electrostatic ion acoustic solitary structures are graphically presented with the relevant physical explanations. This study may be useful for the better understanding of physical phenomena concerned in plasmas in which the effects of trapped electrons control the dynamics of wave.
Choi, M J; Coleman, A J; Saunders, J E
1993-11-01
This study concerns the radial dynamics of a bubble driven by pulsed ultrasound of the type generated during extracorporeal shock wave lithotripsy. In particular, a numerical model has been used to examine the sensitivity of the bubble oscillations to changes in both the amplitude of the driving field and the physical conditions of the fluid surrounding the bubble: viscosity, surface tension, temperature and gas content. It is shown that, at high negative pressures (p- = 10 MPa) as in lithotripsy, the timing and amplitude of bubble collapses have a considerably reduced sensitivity to the initial bubble size and all fluid parameters, except gas content, compared with those expected in lower-amplitude fields (p- = 0.2 MPa). This study indicates that, in the lithotripsy fields, the differences in the viscosity, surface tension and temperature of body fluids and the initial bubble size will have little effect on bubble dynamics compared with those expected in water.
Effect of phase coupling on surface amplitude distribution of wind waves
Varkey, M.J.
Nonlinear features of wind generated surface waves are considered here to be caused by nonrandomness (non-Uniform) in the phase spectrum. Nonrandomness in recorded waves, if present, would be generally obscured within the error level of observations...
Wanjun Lei
2015-01-01
Full Text Available Electric arc furnace (EAF causes the harmonics to impact on the supply network greatly and harmonic elimination is a very important research work for the power quality associated with EAF. In the paper, a fundamental wave amplitude prediction algorithm based on fuzzy neural network for harmonic elimination of EAF current is proposed. The proposed algorithm uses the learning ability of the neural network to refine Takagi-Sugeno type fuzzy rules and the inputs are the average of the current measured value in different time intervals. To verify the effectiveness of the proposed algorithm, some experiments are performed to compare the proposed algorithm with the back-propagation neural networks, and the field data collected at an EAF are used in the experiments. Moreover, the measured amplitudes of fundamental waves of field data are obtained by the sliding-window-based discrete Fourier transform on the field data. The experiments results show that the proposed algorithm has higher precision. The real curves also verify that the amplitude of fundamental wave current could be predicted accurately and the harmonic elimination of EAF would be realized based on the proposed algorithm.
Electron acoustic waves in a magnetized plasma with kappa distributed ions
Devanandhan, S.; Lakhina, G. S. [Indian Institute of Geomagnetism, Navi Mumbai (India); Singh, S. V. [Indian Institute of Geomagnetism, Navi Mumbai (India); School of Physics, University of Kwazulu-Natal, Durban (South Africa); Bharuthram, R. [University of the Western Cape, Bellville (South Africa)
2012-08-15
Electron acoustic solitary waves in a two component magnetized plasma consisting of fluid cold electrons and hot superthermal ions are considered. The linear dispersion relation for electron acoustic waves is derived. In the nonlinear regime, the energy integral is obtained by a Sagdeev pseudopotential analysis, which predicts negative solitary potential structures. The effects of superthermality, obliquity, temperature, and Mach number on solitary structures are studied in detail. The results show that the superthermal index {kappa} and electron to ion temperature ratio {sigma} alters the regime where solitary waves can exist. It is found that an increase in magnetic field value results in an enhancement of soliton electric field amplitude and a reduction in soliton width and pulse duration.
Investigation on laser accelerators. Plasma beat wave accelerators
Miura, Akihiko; Miyamoto, Yasuaki; Hagiwara, Masayoshi; Suzuki, Mitsutoshi; Sudo, Osamu [Power Reactor and Nuclear Fuel Development Corp., Tokai, Ibaraki (Japan). Tokai Works
1998-04-01
Laser accelerator technology has characteristics of high energy, compact, short pulse and high luminescence{center_dot}low emittance. This means potential many applications in wide ranges of fields as well as high energy and nuclear physics. High power short laser pulses are injected to a plasma in the typical example of laser accelerators. Large electric fields are induced in the plasma. Electrons in the plasma are accelerated with the ponderomotive force of the electric field. The principles of interaction on beat wave, wakefield accelerators, inverse free electron laser and inverse Cherenkov radiation are briefly introduced. The overview of plasma beat wave accelerator study is briefly described on the programs at Chalk River Laboratories(Canada), UCLA(USA), Osaka Univ. (Japan) and Ecole Polytechnique (France). Issues of the plasma beat wave accelerator are discussed from the viewpoint of application. Existing laser technologies of CO{sub 2}, YAG and YFL are available for the present day accelerator technology. An acceleration length of beat wave interaction is limited due to its phase condition. Ideas on multi-staged acceleration using the phasing plasma fiber are introduced. (Y. Tanaka)
Kh. H. EL-SHORBAGY
2008-01-01
The effect of a high frequency (HF) electric field on the propagation of electrostatic wave in a 2D non-uniform relativistic plasma waveguide is investigated. A variable separation method is applied to the two-fluid plasma model. An analytical study of the reflection of electro-static wave propagation along a magnetized non-uniform relativistic plasma slab subjected to an intense HF electric field is presented and compared with the case of a non relativistic plasma. It is found that, when the frequency of the incident wave is close to the relativistic electron plasma frequency, the plasma is less reflective due to the presence of both an HF field and the effect of rel-ativistic electrons. On the other hand, for a low-frequency incident wave the reflection coefficient is directly proportional to the amplitude of the HF field. Also, it is shown that the relativistic electron plasma leads to a decrease in the value of reflection coefficient in comparison with the case of the non relativistic plasma.
Giesbertz, Klaas J. H. [Theoretical Chemistry, Faculty of Exact Sciences, VU University, De Boelelaan 1083, 1081 HV Amsterdam (Netherlands); Leeuwen, Robert van [Department of Physics, Nanoscience Center, University of Jyväskylä, P.O. Box 35, 40014 Jyväskylä, Survontie 9, Jyväskylä (Finland)
2014-05-14
Electron correlations in molecules can be divided in short range dynamical correlations, long range Van der Waals type interactions, and near degeneracy static correlations. In this work, we analyze for a one-dimensional model of a two-electron system how these three types of correlations can be incorporated in a simple wave function of restricted functional form consisting of an orbital product multiplied by a single correlation function f (r{sub 12}) depending on the interelectronic distance r{sub 12}. Since the three types of correlations mentioned lead to different signatures in terms of the natural orbital (NO) amplitudes in two-electron systems, we make an analysis of the wave function in terms of the NO amplitudes for a model system of a diatomic molecule. In our numerical implementation, we fully optimize the orbitals and the correlation function on a spatial grid without restrictions on their functional form. Due to this particular form of the wave function, we can prove that none of the amplitudes vanishes and moreover that it displays a distinct sign pattern and a series of avoided crossings as a function of the bond distance in agreement with the exact solution. This shows that the wave function ansatz correctly incorporates the long range Van der Waals interactions. We further show that the approximate wave function gives an excellent binding curve and is able to describe static correlations. We show that in order to do this the correlation function f (r{sub 12}) needs to diverge for large r{sub 12} at large internuclear distances while for shorter bond distances it increases as a function of r{sub 12} to a maximum value after which it decays exponentially. We further give a physical interpretation of this behavior.
Kinetic Alfv\\'{e}n solitary and rogue waves in superthermal plasmas
Bains, A; Xia, L -D
2014-01-01
We investigate the small but finite amplitude solitary Kinetic Alfv\\'{e}n waves (KAWs) in low $\\beta$ plasmas with superthermal electrons modeled by a kappa-type distribution. A nonlinear Korteweg-de Vries (KdV) equation describing the evolution of KAWs is derived by using the standard reductive perturbation method. Examining the dependence of the nonlinear and dispersion coefficients of the KdV equation on the superthermal parameter $\\kappa$, plasma $\\beta$ and obliqueness of propagation, we show that these parameters may change substantially the shape and size of solitary KAW pulses. Only sub-Alfv\\'enic, compressive solitons are supported. We then extend the study to examine kinetic Alfv\\'en rogue waves by deriving a nonlinear Schr\\"{o}dinger equation from {the KdV} equation. Rational solutions that form rogue wave envelopes are obtained. We examine how the behavior of rogue waves depends on the plasma parameters in question, finding that the rogue envelopes are lowered with increasing electron superthermal...
Dust-acoustic solitary waves in a magnetized dusty plasma with nonthermal electrons and trapped ions
Misra, A P
2014-01-01
The nonlinear theory of electrostatic dust-acoustic (DA) waves in a magnetized dusty plasma consisting of negatively charged mobile dusts, nonthermal fast electrons and trapped ions with vortex-like distribution is revisited. Previous theory in the literature [Phys. Plasmas {\\bf 20}, 104505 (2013)] is rectified and put forward to include the effects of the external magnetic field, the adiabatic pressure of charged dusts as well as the obliqueness of propagation to the magnetic field. Using the reductive perturbation technique, a Korteweg-de Vries (KdV)-like equation is derived which governs the dynamics of the small-amplitude solitary waves in a magnetized dusty nonthermal plasma. It is found that due to the dust thermal pressure, there exists a critical value $(\\beta_c)$ of the nothermal parameter $\\beta (>1)$, denoting the percentage of energetic electrons, below which the DA solitary waves cease to propagate. The soliton solution (travelling wave) of the KdV-like equation is obtained, and is shown to be on...
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.
Nekrasov, A K
2013-01-01
We derive the expression for the ponderomotive force in the real multicomponent magnetospheric plasma containing heavy ions. The ponderomotive force considered includes the induced magnetic moment of all the species and arises due to inhomogeneity of the traveling low-frequency electromagnetic wave amplitude in the nonuniform medium. The nonlinear stationary force balance equation is obtained taking into account the gravitational and centrifugal forces for the plasma consisting of the electrons, protons and heavy ions (He$^{+}$). The background geomagnetic field is taken for the dayside of the magnetosphere, where the magnetic field have magnetic "holes" (Antonova and Shabansky 1968). The balance equation is solved numerically to obtain the nonlinear density distribution of ions (H$^{+}$) in the presence of heavy ions (He$^{+}$). It is shown that for frequencies less than the helium gyrofrequency at the equator the nonlinear plasma density perturbations are peaked in the vicinity of the equator due to the act...
Structured waves near the plasma frequency observed in three auroral rocket flights
M. Samara
2006-11-01
Full Text Available We present observations of waves at and just above the plasma frequency (f_{pe} from three high frequency electric field experiments on three recent rockets launched to altitudes of 300–900 km in active aurora. The predominant observed HF waves just above f_{pe} are narrowband, short-lived emissions with amplitudes ranging from <1 mV/m to 20 mV/m, often associated with structured electron density. The nature of these HF waves, as determined from frequency-time spectrograms, is highly variable: in some cases, the frequency decreases monotonically with time as in the "HF-chirps" previously reported (McAdams and LaBelle, 1999, but in other cases rising frequencies are observed, or features which alternately rise and fall in frequency. They exhibit two timescales of amplitude variation: a short timescale, typically 50–100 ms, associated with individual discrete features, and a longer timescale associated with the general decrease in the amplitudes of the emissions as the rocket moves away from where the condition f~f_{pe} holds. The latter timescale ranges from 0.6 to 6.0 s, corresponding to distances of 2–7 km, assuming the phenomenon to be stationary and using the rocket velocity to convert time to distance.
Silantyev, Denis A.; Lushnikov, Pavel M.; Rose, Harvey A.
2017-04-01
We consider two kinds of pumped Langmuir waves (LWs) in the kinetic regime, k λ D ≳ 0.2 , where k is the LW wavenumber and λD is the Debye length, driven to finite amplitude by a coherent external potential whose amplitude is either weak or strong. These dynamically prepared nonlinear LWs develop a transverse (filamentation) instability whose nonlinear evolution destroys the LW's transverse coherence. Instability growth rates in the weakly pumped regime are the same as those of Bernstein-Greene-Kruskal modes considered in Part I (D. A. Silantyev et al., Phys. Plasmas 24, 042104 (2017)), while strongly pumped LWs have higher filamentation grow rates.
Chen, Hao; Yang, Shenglai; Huan, Kangning; Li, Fangfang; Huang, Wei; Zheng, Aiai; Zhang, Xing
2013-09-03
CO2 sequestration has been considered to be one of the most straightforward carbon management strategies for industrial CO2 emission. Monitoring of the CO2 injection process is one of the best ways to make sure the safety storage but is also a major challenge in CO2 geological sequestration. Previous field and laboratory researches have shown that seismic methods are among the most promising monitoring methods because of the obvious reduction in P-wave velocities caused by CO2 injection. However, as CO2 injection continues, the P-wave velocity becomes increasingly insensitive according to the pilot projects when CO2 saturation is higher than 20-40%. Therefore, the conventional seismic method needs improvement or replacement to solve its limitations. In this study, P-wave velocity and amplitude responses to supercritical CO2 injection in brine-saturated core samples from Jilin oilfield were tested using core displacement and an ultrasonic detection integrated system. Results showed that neither the P-wave velocity nor amplitude could simply be used to monitor the CO2 injection process because of the insensitive or nonmonotonous response. Consequently, a new index was established by synthetically considering these two parameters to invert and monitor the CO2 process, which can be thought of as a newer and more effective assessment criterion for the seismic method.
Excitation of Chirping Whistler Waves in a Laboratory Plasma.
Van Compernolle, B; An, X; Bortnik, J; Thorne, R M; Pribyl, P; Gekelman, W
2015-06-19
Whistler mode chorus emissions with a characteristic frequency chirp are important magnetospheric waves, responsible for the acceleration of outer radiation belt electrons to relativistic energies and also for the scattering loss of these electrons into the atmosphere. Here, we report on the first laboratory experiment where whistler waves exhibiting fast frequency chirping have been artificially produced using a beam of energetic electrons launched into a cold plasma. Frequency chirps are only observed for a narrow range of plasma and beam parameters, and show a strong dependence on beam density, plasma density, and magnetic field gradient. Broadband whistler waves similar to magnetospheric hiss are also observed, and the parameter ranges for each emission are quantified.
Spatiotemporal synchronization of drift waves in a magnetron sputtering plasma
Martines, E; Cavazzana, R; Adámek, J; Antoni, V; Serianni, G; Spolaore, M; Vianello, N
2014-01-01
A feedforward scheme is applied for drift waves control in a magnetized magnetron sputtering plasma. A system of driven electrodes collecting electron current in a limited region of the explored plasma is used to interact with unstable drift waves. Drift waves actually appear as electrostatic modes characterized by discrete wavelengths of the order of few centimeters and frequencies of about 100 kHz. The effect of external quasi-periodic, both in time and space, travelling perturbations is studied. Particular emphasis is given to the role played by the phase relation between the natural and the imposed fluctuations. It is observed that it is possible by means of localized electrodes, collecting currents which are negligible with respect to those flowing in the plasma, to transfer energy to one single mode and to reduce that associated to the others. Due to the weakness of the external action, only partial control has been achieved.
Some notes on ideology of waves in plasmas
Soshnikov, V N
2002-01-01
Our last three papers provide an occasion to make some brief notes on ideology of waves in plasmas and to rehabilitate Vlasov prescription to calculate relevant logarithmically divergent integrals in the principal value sense. In this approach asymptotical solutions of plasma oscillations are selected according to self-consistent boundary physical conditions. Landau damping is absent in this case by definition. Boundary electrical field together with conditions of absence of unphysical backward and kinematical waves define single-valued dependence of boundary distribution function on electron velocity \\vec{v} in the case of transversal waves and on the surface break of the normal electrical field in the case of longitudinal oscillations. We have proposed physically more justified modified iteration procedure of collisional damping calculation and demonstrated some results of damping decrements calculations in a low-collision electron-ion plasma. Dispersion smearing of both longitudinal and transversal high-fr...
Vlasov Simulations of Electron-Ion Collision Effects on Damping of Electron Plasma Waves
Banks, J W; Berger, R L; Tran, T M
2016-01-01
Collisional effects can play an essential role in the dynamics of plasma waves by setting a minimum damping rate and by interfering with wave-particle resonances. Kinetic simulations of the effects of electron-ion pitch angle scattering on Electron Plasma Waves (EPWs) are presented here. In particular, the effects of such collisions on the frequency and damping of small-amplitude EPWs for a range of collision rates and wave phase velocities are computed and compared with theory. Both the Vlasov simulations and linear kinetic theory find the direct contribution of electron-ion collisions to wave damping is about a factor of two smaller than is obtained from linearized fluid theory. To our knowledge, this simple result has not been published before. Simulations have been carried out using a grid-based (Vlasov) approach, based on a high-order conservative finite difference method for discretizing the Fokker-Planck equation describing the evolution of the electron distribution function. Details of the implementat...
Dust ion-acoustic shock waves due to dust charge fluctuation in a superthermal dusty plasma
Alinejad, H., E-mail: alinejad@nit.ac.ir [Department of Physics, Faculty of Basic Science, Babol University of Technology, Babol 47148-71167 (Iran, Islamic Republic of); Research Institute for Fundamental Sciences (RIFS), University of Tabriz, 51664, Tabriz (Iran, Islamic Republic of); Tribeche, M. [Plasma Physics Group, Faculty of Sciences – Physics, University of Bab-Ezzouar (Algeria); Mohammadi, M.A. [Research Institute for Fundamental Sciences (RIFS), University of Tabriz, 51664, Tabriz (Iran, Islamic Republic of); Department of Atomic and Molecular Physics, Faculty of Physics, University of Tabriz, Tabriz (Iran, Islamic Republic of)
2011-11-14
The nonlinear propagation of dust ion-acoustic (DIA) shock waves is studied in a charge varying dusty plasma with electrons having kappa velocity distribution. We use hot ions with equilibrium streaming speed and a fast superthermal electron charging current derived from orbit limited motion (OLM) theory. It is found that the presence of superthermal electrons does not only significantly modify the basic properties of shock waves, but also causes the existence of shock profile with only positive potential in such plasma with parameter ranges corresponding to Saturn's rings. It is also shown that the strength and steepness of the shock waves decrease with increase of the size of dust grains and ion temperature. -- Highlights: ► The presence of superthermal electrons causes the existence of shock waves with only positive potential. ► The strength and steepness of the shock waves decrease with increase of the size of dust grains and ion temperature. ► As the electrons evolve toward their thermodynamic equilibrium, the shock structures are found with smaller amplitude.
Study on the electromagnetic waves propagation characteristics in partially ionized plasma slabs
Zhi-Bin Wang
2016-05-01
Full Text Available Propagation characteristics of electromagnetic (EM waves in partially ionized plasma slabs are studied in this paper. Such features are significant to applications in plasma antennas, blackout of re-entry flying vehicles, wave energy injection to plasmas, and etc. We in this paper developed a theoretical model of EM wave propagation perpendicular to a plasma slab with a one-dimensional density inhomogeneity along propagation direction to investigate essential characteristics of EM wave propagation in nonuniform plasmas. Particularly, the EM wave propagation in sub-wavelength plasma slabs, where the geometric optics approximation fails, is studied and in comparison with thicker slabs where the geometric optics approximation applies. The influences of both plasma and collisional frequencies, as well as the width of the plasma slab, on the EM wave propagation characteristics are discussed. The results can help the further understanding of propagation behaviours of EM waves in nonuniform plasma, and applications of the interactions between EM waves and plasmas.
Dust-acoustic waves modulational instability and rogue waves in a polarized dusty plasma
Bouzit, Omar; Tribeche, Mouloud [Faculty of Physics, Theoretical Physics Laboratory, Plasma Physics Group, University of Bab-Ezzouar, USTHB, B.P. 32, El Alia, Algiers 16111 (Algeria)
2015-10-15
The polarization force-induced changes in the dust-acoustic waves (DAWs) modulational instability (MI) are examined. Using the reductive perturbation method, the nonlinear Schrödinger equation that governs the MI of the DAWs is obtained. It is found that the effect of the polarization term R is to narrow the wave number domain for the onset of instability. The amplitude of the wave envelope decreases as R increases, meaning that the polarization force effects render weaker the associated DA rogue waves. The latter may therefore completely damp in the vicinity of R ∼ 1, i.e., as the polarization force becomes close to the electrostatic one (the net force acting on the dust particles becomes vanishingly small). The DA rogue wave profile is very sensitive to any change in the restoring force acting on the dust particles. It turns out that the polarization effects may completely smear out the DA rogue waves.
Formation of Large-Amplitude Wave Groups in an Experimental Model Basin
2008-08-01
Tm= 3.0s with large grouped waves embedded C -46 Figure 95. Spectral Analysis of Phase II, Run 26- Hurricane Camille, ?i=30, Hs= 40.64 cm (16.0 in...Tm= 2.45s with wave group embedded C -47 Figure 96. Spectral Analysis of Phase II, Run 40- Hurricane Camille, ^=46.6, Hs= 26.16 cm (10.3 in.), Tm...1.96s with wave group embedded C -48 Figure 97. Three-dimensional wave surface plots for Phase II, Run 7 D-2 Figure 98. GLRP Single Point Time History
Solar Wind Strahl Broadening by Self-Generated Plasma Waves
Pavan, J.; Vinas, A. F.; Yoon, P. H.; Ziebell, L. F.; Gaelzer, R.
2013-01-01
This Letter reports on the results of numerical simulations which may provide a possible explanation for the strahl broadening during quiet solar conditions. The relevant processes involved in the broadening are due to kinetic quasi-linear wave-particle interaction. Making use of static analytical electron distribution in an inhomogeneous field, it is found that self-generated electrostatic waves at the plasma frequency, i.e., Langmuir waves, are capable of scattering the strahl component, resulting in energy and pitch-angle diffusion that broadens its velocity distribution significantly. The present theoretical results provide an alternative or complementary explanation to the usual whistler diffusion scenario, suggesting that self-induced electrostatic waves at the plasma frequency might play a key role in broadening the solar wind strahl during quiet solar conditions.
Accumulative coupling between magnetized tenuous plasma and gravitational waves
Zhang, Fan
2016-07-01
We explicitly compute the plasma wave (PW) induced by a plane gravitational wave (GW) traveling through a region of strongly magnetized plasma, governed by force-free electrodynamics. The PW comoves with the GW and absorbs its energy to grow over time, creating an essentially force-free counterpart to the inverse-Gertsenshtein effect. The time-averaged Poynting flux of the induced PW is comparable to the vacuum case, but the associated current may offer a more sensitive alternative to photodetection when designing experiments for detecting/constraining high-frequency gravitational waves. Aside from the exact solutions, we also offer an analysis of the general properties of the GW to PW conversion process, which should find use when evaluating electromagnetic counterparts to astrophysical gravitational waves that are generated directly by the latter as a second-order phenomenon.
Accumulative coupling between magnetized tenuous plasma and gravitational waves
Zhang, Fan
2016-01-01
We explicitly compute the plasma wave (PW) induced by a plane gravitational wave (GW) travelling through a region of strongly magnetized plasma, governed by force-free electrodynamics. The PW co-moves with the GW and absorbs its energy to grow over time, creating an essentially force-free counterpart to the inverse-Gertsenshtein effect. The time-averaged Poynting flux of the induced PW is comparable to the vacuum case, but the associated current may offer a more sensitive alternative to photodetection when designing experiments for detecting/constraining high frequency gravitational waves. Aside from the exact solutions, we also offer an analysis of the general properties of the GW to PW conversion process, which should find use when evaluating electromagnetic counterparts to astrophysical gravitational waves, that are generated directly by the latter as a second order phenomenon.
Electromagnetic waves in a magnetized plasma near the critical surface
Timofeev, Aleksandr V [Russian Research Centre ' Kurchatov Institute' , Moscow (Russian Federation)
2004-06-30
Electromagnetic waves in a plasma in a magnetic field give rise to enhanced refraction, produce a change in polarization, and cause electromagnetic energy to flow from one wave mode to another when propagating near the critical surface (CS), the one where the electron Langmuir frequency is equal to the wave frequency. A simple unified model of all phenomena taking place near the CS is proposed. These phenomena are due to electromagnetic waves linearly interacting with electron Langmuir oscillations which are localized at the CS in a cold plasma. This interaction manifests itself most strikingly in electron Langmuir oscillation energy escaping directly into a vacuum in the form of electromagnetic radiation. (reviews of topical problems)
Full-wave solution of short impulses in inhomogeneous plasma
Orsolya E Ferencz
2005-02-01
In this paper the problem of real impulse propagation in arbitrarily inhomogeneous media will be presented on a fundamentally new, general, theoretical way. The general problem of wave propagation of monochromatic signals in inhomogeneous media was enlightened in [1]. The earlier theoretical models for spatial inhomogeneities have some errors regarding the structure of the resultant signal originated from backward and forward propagating parts. The application of the method of inhomogeneous basic modes (MIBM) and the complete full-wave solution of arbitrarily shaped non-monochromatic plane waves in plasmas made it possible to obtain a better description of the problem, on a fully analytical way, directly from Maxwell's equations. The model investigated in this paper is inhomogeneous of arbitrary order (while the wave pattern can exist), anisotropic (magnetized), linear, cold plasma, in which the gradient of the one-dimensional spatial inhomogeneity is parallel to the direction of propagation.
Theoretical and Experimental Study of Scattering of a Plane Wave by an Inhomogeneous Plasma Sphere
SONG Fa-Lun; CAO Jin-Xiang; WANG Ge; WANG Yan; ZHU Ying; ZHU Jian; WANG Liang; NIU Tian-Ye
2006-01-01
@@ Scattering of electromagnetic waves by an inhomogeneous plasma sphere has been studied theoretically and experimentally. The offset angles of electromagnetic waves caused by the plasma sphere have been observed experimentally. The effects of the electromagnetic wave frequency and plasma density on the offset angle are discussed. The plasma density is estimated with the offset angle.
Yang Min; Li Xiaoping; Xie Kai; Liu Donglin [School of Electronical and Mechanical Engineering, Xidian University, Xi' an Shaanxi 710071 (China); Liu Yanming [School of Telecommunications Engineering, Xidian University, Xi' an Shaanxi 710071 (China)
2013-01-15
A large volume uniform plasma generator is proposed for the experiments of electromagnetic (EM) wave propagation in plasma, to reproduce a 'black out' phenomenon with long duration in an environment of the ordinary laboratory. The plasma generator achieves a controllable approximate uniform plasma in volume of 260 mm Multiplication-Sign 260 mm Multiplication-Sign 180 mm without the magnetic confinement. The plasma is produced by the glow discharge, and the special discharge structure is built to bring a steady approximate uniform plasma environment in the electromagnetic wave propagation path without any other barriers. In addition, the electron density and luminosity distributions of plasma under different discharge conditions were diagnosed and experimentally investigated. Both the electron density and the plasma uniformity are directly proportional to the input power and in roughly reverse proportion to the gas pressure in the chamber. Furthermore, the experiments of electromagnetic wave propagation in plasma are conducted in this plasma generator. Blackout phenomena at GPS signal are observed under this system and the measured attenuation curve is of reasonable agreement with the theoretical one, which suggests the effectiveness of the proposed method.
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.
Laser-driven plasma waves in capillary tubes.
Wojda, F; Cassou, K; Genoud, G; Burza, M; Glinec, Y; Lundh, O; Persson, A; Vieux, G; Brunetti, E; Shanks, R P; Jaroszynski, D; Andreev, N E; Wahlström, C-G; Cros, B
2009-12-01
The excitation of plasma waves over a length of up to 8 cm is demonstrated using laser guiding of intense laser pulses through hydrogen-filled glass capillary tubes. The plasma waves are diagnosed by spectral analysis of the transmitted laser radiation. The dependence of the spectral redshift-measured as a function of filling pressure, capillary tube length, and incident laser energy-is in excellent agreement with simulation results. The longitudinal accelerating field inferred from the simulations is in the range of 1-10 GV/m.
On the rogue wave propagation in ion pair superthermal plasma
Abdelwahed, H. G., E-mail: hgomaa-eg@yahoo.com, E-mail: hgomaa-eg@mans.edu.eg; Zahran, M. A. [Physics Department, College of Sciences and Humanities Studies Al-Kharj, Prince Sattam Bin Abdulaziz University, Al-Kharj (Saudi Arabia); Theoretical Physics Group, Physics Department, Faculty of Science, Mansoura University, Mansoura (Egypt); El-Shewy, E. K., E-mail: emadshewy@yahoo.com; Elwakil, S. A. [Theoretical Physics Group, Physics Department, Faculty of Science, Mansoura University, Mansoura (Egypt)
2016-02-15
Effects of superthermal electron on the features of nonlinear acoustic waves in unmagnetized collisionless ion pair plasma with superthermal electrons have been examined. The system equations are reduced in the form of the nonlinear Schrodinger equation. The rogue wave characteristics dependences on the ionic density ratio (ν = n{sub –0}/n{sub +0}), ionic mass ratio (Q = m{sub +}/m{sub −}), and superthermality index (κ) are investigated. It is worth mentioning that the results present in this work could be applicable in the Earth's ionosphere plasmas.
Refraction of VHF radio waves in artificial plasma formations
Kashirin, A. I.; Kliueva, N. M.; Mikhailik, P. P.; Chkalov, V. G.
1991-09-01
The defocusing refraction of VHF waves during the radio occultation of artificial plasma clouds in the ionosphere is calculated in the framework of the geometrical-optics approximation. The possibility of determining the main cloud parameters from characteristic power variations of the received radio waves in the case of a monotonic change in the sighting parameter during the experiment is demonstrated. Results of a rocket experiment implementing this method are presented.
1988-10-18
Mantle Boundary Inferred from Short-Period Scattered PKP Waves Recorded at the Global Digital Seismograph Network KLAUS BATAILLE AND STANILY M. F...Geophys. Res., 78, Osemov, L A., Wave Propagation in a Random Medium, Mc Graw - 6009--6020, 1973. Hill, New York, 1960. Morelli, A., and A. M
Dadashi, Mohsen; Birashk, Behrooz; Taremian, Farhad; Asgarnejad, Ali Asghar; Momtazi, Saeed
2015-01-01
The basic objective of this study is to investigate the effects of alpha and theta brain waves amplitude increase in occipital area on reducing the severity of symptoms of generalized anxiety disorder and to increase the global functioning level in patients with GAD. This study is a quasi-experimental study with pre-test and post-test with two groups. For this purpose, 28 patients who had been referred to Sohrawardi psychiatric and clinical psychology center in Zanjan were studied based on the interview with the psychiatrist, clinical psychologist and using clinical diagnostic criteria for the Diagnostic and Statistical Manual of Mental Disorders text revision - the DSM-IV-TR Fourth Edition diagnosis of GAD, 14 subjects were studied in neurofeedback treatment group and 14 subjects in the waiting list group. Patients in both groups were evaluated at pre-test and post-test with General Anxiety Disorder Scale (GAD-7) and Global Assessment Functioning Scale (GAFs). The treatment group received fifteen 30-minute alpha training sessions and fifteen 30-minute theta brain training sessions in occipital area by neurofeedback training (treatment group). This evaluation was performed according to the treatment protocol to increase the alpha and theta waves. And no intervention was done in the waiting list group. But due to ethical issues after the completion of the study all the subjects in the waiting list group were treated. The results showed that increase of alpha and theta brain waves amplitude in occipital area in people with GAD can increase the global functioning level and can reduce symptoms of generalized anxiety disorder in a treatment group, but no such change was observed in the waiting list group. Increase of alpha and theta brain waves amplitude in occipital area can be useful in the treatment of people with GAD.
Collisionless damping of electron waves in non-Maxwellian plasma
Soshnikov, V. N.
2007-01-01
In this paper we have criticized the so-called Landau damping theory. We have analyzed solutions of the standard dispersion equations for longitudinal (electric) and transversal (electromagnetic and electron) waves in half-infinite slab of the uniform collisionless plasmas with non-Maxwellian and Maxwellian-like electron energy distribution functions. One considered the most typical cases of both the delta-function type distribution function (the plasma stream with monochromatic electrons) an...
Phase conjugation by four-wave mixing in inhomogeneous plasmas
Williams, Edward A.; Lininger, Diana M.; Goldman, Martin V.
1989-01-01
The effects of density, temperature, and velocity gradients on four-wave mixing (FWM) in a plasma are investigated. A fluid model is used in which the stimulated Brillouin terms are included, but pump depletion is neglected. The steady state phase conjugate reflectivity and signal transmission coefficients are calculated and discussed for both degenerate and resonant FWM. The substantial effects of inhomogeneity on the use of FWM as a plasma diagnostic are discussed.
Electron plasma wave filamentation in the kinetic regime
Lushnikov, Pavel; Rose, Harvey; Silantyev, Denis
2016-10-01
We consider nonlinear electron plasma wave (EPW) dynamics in the kinetic wavenumber regime, 0.25 Bernstein-Greene-Kruskal (BGK) mode. Transverse perturbations of any of these initial conditions grow with time eventually producing strongly nonlinear filamentation followed by plasma turbulence. We compared these simulations with the theoretical results on growth rates of the transverse instability BGK mode showing the satisfactory agreement. Supported by the New Mexico Consortium and NSF DMS-1412140.
Follett, R. K., E-mail: rfollett@lle.rochester.edu; Delettrez, J. A.; Edgell, D. H.; Henchen, R. J.; Katz, J.; Myatt, J. F.; Froula, D. H. [Laboratory for Laser Energetics, University of Rochester, 250 East River Road, Rochester, New York 14623 (United States)
2016-11-15
Collective Thomson scattering is a technique for measuring the plasma conditions in laser-plasma experiments. Simultaneous measurements of ion-acoustic and electron plasma-wave spectra were obtained using a 263.25-nm Thomson-scattering probe beam. A fully reflective collection system was used to record light scattered from electron plasma waves at electron densities greater than 10{sup 21} cm{sup −3}, which produced scattering peaks near 200 nm. An accurate analysis of the experimental Thomson-scattering spectra required accounting for plasma gradients, instrument sensitivity, optical effects, and background radiation. Practical techniques for including these effects when fitting Thomson-scattering spectra are presented and applied to the measured spectra to show the improvements in plasma characterization.
Follett, R. K.; Delettrez, J. A.; Edgell, D. H.; Henchen, R. J.; Katz, J.; Myatt, J. F.; Froula, D. H.
2016-11-01
Collective Thomson scattering is a technique for measuring the plasma conditions in laser-plasma experiments. Simultaneous measurements of ion-acoustic and electron plasma-wave spectra were obtained using a 263.25-nm Thomson-scattering probe beam. A fully reflective collection system was used to record light scattered from electron plasma waves at electron densities greater than 1021 cm-3, which produced scattering peaks near 200 nm. An accurate analysis of the experimental Thomson-scattering spectra required accounting for plasma gradients, instrument sensitivity, optical effects, and background radiation. Practical techniques for including these effects when fitting Thomson-scattering spectra are presented and applied to the measured spectra to show the improvements in plasma characterization.
Degenerate mixing of plasma waves on cold, magnetized single-species plasmas
Anderson, M. W.; O' Neil, T. M.; Dubin, D. H. E.; Gould, R. W. [Physics Department, University of California at San Diego, La Jolla, California 92093 (United States)
2011-10-15
In the cold-fluid dispersion relation {omega}={omega}{sub p}/[1+(k{sub perpendicular}/k{sub z}){sup 2}]{sup 1/2} for Trivelpiece-Gould waves on an infinitely long magnetized plasma cylinder, the transverse and axial wavenumbers appear only in the combination k{sub perpendicular}/k{sub z}. As a result, for any frequency {omega}<{omega}{sub p}, there are infinitely many degenerate waves, all having the same value of k{sub perpendicular}/k{sub z}. On a cold finite-length plasma column, these degenerate waves reflect into one another at the ends; thus, each standing-wave normal mode of the bounded plasma is a mixture of many degenerate waves, not a single standing wave as is often assumed. A striking feature of the many-wave modes is that the short-wavelength waves often add constructively along resonance cones given by dz/dr={+-}({omega}{sub p}{sup 2}/{omega}{sup 2}-1){sup 1/2}. Also, the presence of short wavelengths in the admixture for a predominantly long-wavelength mode enhances the viscous damping beyond what the single-wave approximation would predict. Here, numerical solutions are obtained for modes of a cylindrical plasma column with rounded ends. Exploiting the fact that the modes of a spheroidal plasma are known analytically (the Dubin modes), a perturbation analysis is used to investigate the mixing of low-order, nearly degenerate Dubin modes caused by small deformations of a plasma spheroid.
The incomplete plasma dispersion function: properties and application to waves in bounded plasmas
Baalrud, Scott D.
2013-01-01
The incomplete plasma dispersion function is a generalization of the plasma dispersion function in which the defining integral spans a semi-infinite, rather than infinite, domain. It is useful for describing the linear dielectric response and wave dispersion in non-Maxwellian plasmas when the distribution functions can be approximated as Maxwellian over finite, or semi-infinite, intervals in velocity phase-space. A ubiquitous example is the depleted Maxwellian electron distribution found near...
Statistics of Amplitude and Fluid Velocity of Large and Rare Waves in the Ocean
2007-06-01
Hextreme_max Maximum crest-to-trough height meters Hs Significant wave height meters Hs100 Extreme significant wave height with the 100 year return period...NHsHsP −=< (3.1-7) Where: Hs100 = extreme significant wave height with the 100 year return period D = a decorrelation time scale in hours for...between the buoy-derived extreme Hs with the return period of 100 years and the Hs100 based on IDM and POT differed by less than 10% (under 5% for all but
RF wave propagation and scattering in turbulent tokamak plasmas
Horton, W., E-mail: wendell.horton@gmail.com; Michoski, C. [Institute for Fusion Studies, The University of Texas at Austin, Austin, TX 78654 (United States); Peysson, Y.; Decker, J. [CEA, IRFM, 13108, Saint-Paul, Durance Cedex (France)
2015-12-10
Drift wave turbulence driven by the steep electron and ion temperature gradients in H-mode divertor tokamaks produce scattering of the RF waves used for heating and current drive. The X-ray emission spectra produced by the fast electrons require the turbulence broaden RF wave spectrum. Both the 5 GHz Lower Hybrid waves and the 170 GHz electron cyclotron [EC] RF waves experience scattering and diffraction by the electron density fluctuations. With strong LHCD there are bifurcations in the coupled turbulent transport dynamics giving improved steady-state confinement states. The stochastic scattering of the RF rays makes the prediction of the distribution of the rays and the associated particle heating a statistical problem. Thus, we introduce a Fokker-Planck equation for the probably density of the RF rays. The general frame work of the coupled system of coupled high frequency current driving rays with the low-frequency turbulent transport determines the profiles of the plasma density and temperatures.
Hong-Yan Wang; Kai-Biao Zhang
2015-01-01
Propagation of small but finite nonlinear dust-acoustic solitary waves are investigated in a planar unmagnetized dusty plasma, which consists of electrons, positrons, ions and negatively charged dust particles with different sizes and masses. A Kadomtsev–Petviashvili (KP) equation is obtained by using reductive perturbation method. The effect of positron density and positron–electron temperature ratio on dust-acoustic solitary structures are studied. Numerical results show that the increase in positron number density increases the amplitude of hump-like solitons but decreases the dip-like solitary waves. Furthermore, increase in the positron–electron temperature ratio results in the decrease of the amplitude of dip-like solitary waves. It seems that both the dipand hump-like solitary waves can exist in this system. Our results also suggest that the dust-size distribution has a significant role on the amplitude of the solitary waves.
Estimation of Plasma Density by Surface Plasmons for Surface-Wave Plasmas
CHEN Zhao-Quan; LIU Ming-Hai; LAN Chao-Hui; CHEN Wei; LUO Zhi-Qing; HU Xi-Wei
2008-01-01
@@ An estimation method of plasma density based on surface plasmons theory for surface-wave plasmas is proposed. The number of standing-wave is obtained directly from the discharge image, and the propagation constant is calculated with the trim size of the apparatus in this method, then plasma density can be determined with the value of 9.1 × 1017 m-3. Plasma density is measured using a Langmuir probe, the value is 8.1 × 1017 m-3 which is very close to the predicted value of surface plasmons theory. Numerical simulation is used to check the number of standing-wave by the finite-difference time-domain (FDTD) method also. All results are compatible both of theoretical analysis and experimental measurement.
Nehmetallah, George; Donoghue, John; Banerjee, Partha; Khoury, Jed; Yamamoto, Michiharu; Peyghambarian, Nasser
2016-04-01
In this work, brief theoretical modeling, analysis, and novel numerical verification of a photorefractive polymer based four wave mixing (FWM) setup for defect detection has been developed. The numerical simulation helps to validate our earlier experimental results to perform defect detection in periodic amplitude and phase objects using FWM. Specifically, we develop the theory behind the detection of isolated defects, and random defects in amplitude, and phase periodic patterns. In accordance with the developed theory, the results show that this technique successfully detects the slightest defects through band-pass intensity filtering and requires minimal additional post image processing contrast enhancement. This optical defect detection technique can be applied to the detection of production line defects, e.g., scratch enhancement, defect cluster enhancement, and periodic pattern dislocation enhancement. This technique is very useful in quality control systems, production line defect inspection, and computer vision.
Modulated amplitude waves with non-trivial phase in quasi-1D inhomogeneous Bose–Einstein condensates
Torres, Pedro J., E-mail: ptorres@ugr.es
2014-10-03
We consider a 1D nonlinear Schrödinger equation (NLSE) which describes the mean field dynamics of an elongated Bose–Einstein condensate and prove the existence of modulated amplitude waves with non-trivial phase and minimal spatial period tending to infinite. The proof combines the theory of local continuation of non-degenerate periodic solutions with a property of the Ermakov–Pinney equation. - Highlights: • A rigorous proof of the existence of rotating MAWs in an inhomogeneous BEC. • No condition on the sign or the magnitude of the trap or the scattering length. • Non-trivial phase leads to a singular ODE for the amplitude. • The proof combines a local continuation theorem and properties of rotation numbers.
Interaction of High Intensity Electromagnetic Waves with Plasmas
G. Shvets
2008-10-03
The focus of our work during the duration of this grant was on the following areas: (a) the fundamental plasma physics of intense laser-plasma interactions, including the nonlinear excitation of plasma waves for accelerator applications, as well as the recently discovered by us phenomenon of the relativistic bi-stability of relativistic plasma waves driven by a laser beatwave; (b) interaction of high power microwave beams with magnetized plasma, including some of the recently discovered by us phenomena such as the Undulator Induced Transparency (UIT) as well as the new approaches to dynamic manipulation of microwave pulses; (c) investigations of the multi-color laser pulse interactions in the plasma, including the recently discovered by us phenomenon of Electromagnetic Cascading (EC) and the effect of the EC of three-dimensional dynamics of laser pulses (enhanced/suppressed selffocusing etc.); (d) interaction of high-current electron beams with the ambient plasma in the context of Fast Ignitor (FI) physics, with the emphasis on the nonlinear dynamics of the Weibel instability and beam filamentation.
Fourier spectrum and shape evolution of an internal Riemann wave of moderate amplitude
E. Kartashova
2013-08-01
Full Text Available The nonlinear deformation of long internal waves in the ocean is studied using the dispersionless Gardner equation. The process of nonlinear wave deformation is determined by the signs of the coefficients of the quadratic and cubic nonlinear terms; the breaking time depends only on their absolute values. The explicit formula for the Fourier spectrum of the deformed Riemann wave is derived and used to investigate the evolution of the spectrum of the initially pure sine wave. It is shown that the spectrum has exponential form for small times and a power asymptotic before breaking. The power asymptotic is universal for arbitrarily chosen coefficients of the nonlinear terms and has a slope close to –8/3.
D. Yu. Klimushkin
2006-09-01
Full Text Available The paper employs the frame of a 1-D inhomogeneous model of space plasma,to examine the spatial structure and growth rate of drift mirror modes, often suggested for interpreting some oscillation types in space plasma. Owing to its coupling with the Alfvén mode, the drift mirror mode attains dispersion across magnetic shells (dependence of the frequency on the wave-vector's radial component, k_{r}. The spatial structure of a mode confined across magnetic shells is studied. The scale of spatial localization of the wave is shown to be determined by the plasma inhomogeneity scale and by the azimuthal component of the wave vector. The wave propagates across magnetic shells, its amplitude modulated along the radial coordinate by the Gauss function. Coupling with the Alfvén mode strongly influences the growth rate of the drift mirror instability. The mirror mode can only exist in a narrow range of parameters. In the general case, the mode represents an Alfvén wave modified by plasma inhomogeneity.
First results from the Cluster wideband plasma wave investigation
D. A. Gurnett
Full Text Available In this report we present the first results from the Cluster wideband plasma wave investigation. The four Cluster spacecraft were successfully placed in closely spaced, high-inclination eccentric orbits around the Earth during two separate launches in July – August 2000. Each spacecraft includes a wideband plasma wave instrument designed to provide high-resolution electric and magnetic field wave-forms via both stored data and direct downlinks to the NASA Deep Space Network. Results are presented for three commonly occurring magnetospheric plasma wave phenomena: (1 whistlers, (2 chorus, and (3 auroral kilometric radiation. Lightning-generated whistlers are frequently observed when the spacecraft is inside the plasmasphere. Usually the same whistler can be detected by all spacecraft, indicating that the whistler wave packet extends over a spatial dimension at least as large as the separation distances transverse to the magnetic field, which during these observations were a few hundred km. This is what would be expected for nonducted whistler propagation. No case has been found in which a strong whistler was detected at one spacecraft, with no signal at the other spacecraft, which would indicate ducted propagation. Whistler-mode chorus emissions are also observed in the inner region of the magnetosphere. In contrast to lightning-generated whistlers, the individual chorus elements seldom show a one-to-one correspondence between the spacecraft, indicating that a typical chorus wave packet has dimensions transverse to the magnetic field of only a few hundred km or less. In one case where a good one-to-one correspondence existed, significant frequency variations were observed between the spacecraft, indicating that the frequency of the wave packet may be evolving as the wave propagates. Auroral kilometric radiation, which is an intense radio emission generated along the auroral field lines, is frequently observed over the polar regions. The
Magneto-Hydro-Dynamic Waves In The Collisionless Space Plasma
Dzhalilov, N. S.; Kuznetsov, V. D.; Staude, J.
2007-12-01
The instability of magneto-hydro-dynamic (MHD) waves in an anisotropic, collisionless, rarefied hot plasma is studied. Anisotropy properties of such a plasma are caused by a strong magnetic field, when the thermal gas pressures across and along the field become unequal. Moreover, there appears an anisotropy of the thermal fluxes. The study of the anisotropy features of the plasma are motivated by observed solar coronal data. The 16 moments equations derived from the Boltzmann-Vlasov kinetic equation are used. These equations strongly differ from the usual isotropic MHD case. For linear disturbances the wave equations in homogenous anisotropic plasma are deduced. The general dispersion relation for the incompressible wave modes is derived, solved and analyzed. It is shown that a wide wave spectrum with stable and unstable behavior is possible, in contrast to the usual isotropic MHD case. The dependence of the instability on magnetic field, pressure anisotropy, and heat fluxes is investigated. The general instability condition is obtained. The results can be applied to the theory of solar and stellar coronal heating, to wind models and in other modeling, where the collisionless approximation is valid.
Gribin, V. G.; Gavrilov, I. Yu.; Tishchenko, A. A.; Tishchenko, V. A.; Alekseev, R. A.
2017-05-01
This paper is devoted to the wave structure of a flow at its near- and supersonic velocities in a flat turbine cascade of profiles in the zone of phase transitions. The main task was investigation of the mechanics of interaction of the condensation jump with the adiabatic jumps of packing in a change of the initial condition of the flow. The obtained results are necessary for verification of the calculation models of the moisture-steam flow in the elements of lotic parts of the steam turbines. The experimental tests were made on a stand of the wet steam contour (WSC-2) in the Moscow Power Engineering Institute (MPEI, National Research University) at various initial states of steam in a wide range of Mach numbers. In the investigation of the wave structure, use was made of an instrument based on the Schlieren-method principle. The amplitude-frequency characteristics of the flow was found by measurement of static pressure pulsations by means of the piezo resistive sensors established on a bandage plate along the bevel cut of the cascade. It is shown that appearance of phase transitions in the bevel cut of the nozzle turbine cascade leads to a change in the wave structure of the flow. In case of condensation jump, the system of adiabatic jumps in the bevel cut of the cascade becomes nonstationary, and the amplitude-frequency characteristics of static pressure pulsations are restructured. In this, a change in the frequency pulsations of pressure and amplitude takes place. It is noted that, at near-sonic speeds of the flow and the state of saturation at the input, the low-frequency pulsations of static pressure appear that lead to periodic disappearance of the condensation jump and of the adiabatic jump. As a result, in this mode, the flow discharge variations take place.
Surface Wave Propagation in non--ideal plasmas
Pandey, B P
2015-01-01
The properties of surface waves in a partially ionized, compressible magnetized plasma slab are investigated in this work. The waves are affected by the nonideal magnetohydrodynamic effects which causes finite drift of the magnetic field in the medium. When the magnetic field drift is ignored, the characteristics of the wave propagation in a partially ionized plasma fluid is similar to the fully ionized ideal MHD except now the propagation properties depend on the fractional ionization as well as on the compressibility of the medium. The phase velocity of the sausage and kink waves increases marginally (by a few percent) due to the compressibility of the medium in both ideal as well as Hall diffusion dominated regimes. However, unlike ideal regime, only waves below certain cut off frequency can propagate in the medium in Hall dominated regime. This cut off for a thin slab has a weak dependence on the plasma beta whereas for thick slab no such dependence exists. More importantly, since the cut off is introduce...
Revisiting linear plasma waves for finite value of the plasma parameter
Grismayer, Thomas; Fahlen, Jay; Decyk, Viktor; Mori, Warren
2010-11-01
We investigate through theory and PIC simulations the Landau-damping of plasma waves with finite plasma parameter. We concentrate on the linear regime, γφB, where the waves are typically small and below the thermal noise. We simulate these condition using 1,2,3D electrostatic PIC codes (BEPS), noting that modern computers now allow us to simulate cases where (nλD^3 = [1e2;1e6]). We study these waves by using a subtraction technique in which two simulations are carried out. In the first, a small wave is initialized or driven, in the second no wave is excited. The results are subtracted to provide a clean signal that can be studied. As nλD^3 is decreased, the number of resonant electrons can be small for linear waves. We show how the damping changes as a result of having few resonant particles. We also find that for small nλD^3 fluctuations can cause the electrons to undergo collisions that eventually destroy the initial wave. A quantity of interest is the the life time of a particular mode which depends on the plasma parameter and the wave number. The life time is estimated and then compared with the numerical results. A surprising result is that even for large values of nλD^3 some non-Vlasov discreteness effects appear to be important.
Solitary and freak waves in superthermal plasma with ion jet
Abdelsalam, U. M.; Abdelsalam
2013-06-01
The nonlinear solitary and freak waves in a plasma composed of positive and negative ions, superthermal electrons, ion beam, and stationary dust particles have been investigated. The reductive perturbation method is used to obtain the Korteweg-de Vries (KdV) equation describing the system. The latter admits solitary wave solution, while the dynamics of the modulationally unstable wavepackets described by the KdV equation gives rise to the formation of freak/rogue excitation described by the nonlinear Schrödinger equation. In order to show that the characteristics of solitary and freak waves are influenced by plasma parameters, relevant numerical analysis of appropriate nonlinear solutions are presented. The results from this work predict nonlinear excitations that may associate with ion jet and superthermal electrons in Herbig-Haro objects.
Park, Seong Hyun; Kim, Jong Beom; Jhang, Kyung Young [Hanyang University, Seoul (Korea, Republic of)
2017-02-15
A nonlinear ultrasonic parameter is defined by the ratio of displacement amplitude of the fundamental frequency component to that of the second-order harmonic frequency component. In this study, the ultrasonic displacement amplitude of an SUS316 specimen was measured via a piezo-electric-based method to identify the validity of piezo-electric detection method. For comparison, the ultrasonic displacement was also determined via a laser-based Fabry-Pérot interferometer. The experimental results for both measurements were in good agreement. Additionally, the stability of the repeated test results from the piezo-electric method exceeded that of the laser-interferometric method. This result indicated that the piezo-electric detection method can be utilized to measure a nonlinear ultrasonic parameter due to its excellent stability although it involves a complicated process.
Generation of Diffuse Large Volume Plasma by an Ionization Wave from a Plasma Jet
Laroussi, Mounir; Razavi, Hamid
2015-09-01
Low temperature plasma jets emitted in ambient air are the product of fast ionization waves that are guided within a channel of a gas flow, such as helium. This guided ionization wave can be transmitted through a dielectric material and under some conditions can ignite a discharge behind the dielectric material. Here we present a novel way to produce large volume diffuse low pressure plasma inside a Pyrex chamber that does not have any electrodes or electrical energy directly applied to it. The diffuse plasma is ignited inside the chamber by a plasma jet located externally to the chamber and that is physically and electrically unconnected to the chamber. Instead, the plasma jet is just brought in close proximity to the external wall/surface of the chamber or to a dielectric tubing connected to the chamber. The plasma thus generated is diffuse, large volume and with physical and chemical characteristics that are different than the external plasma jet that ignited it. So by using a plasma jet we are able to ``remotely'' ignite volumetric plasma under controlled conditions. This novel method of ``remote'' generation of a low pressure, low temperature diffuse plasma can be useful for various applications including material processing and biomedicine.
Ni, Binbin; Thorne, Richard M.; Horne, Richard B.; Meredith, Nigel P.; Shprits, Yuri Y.; Chen, Lunjin; Li, Wen
2011-04-01
Using statistical wave power spectral profiles obtained from CRRES and the latitudinal distributions of wave propagation modeled by the HOTRAY code, a quantitative analysis has been performed on the scattering of plasma sheet electrons into the diffuse auroral zone by multiband electrostatic electron cyclotron harmonic (ECH) emissions near L = 6 within the 0000-0600 MLT sector. The results show that ECH wave scattering of plasma sheet electrons varies from near the strong diffusion rate (timescale of an hour or less) during active times with peak wave amplitudes of an order of 1 mV/m to very weak scattering (on the timescale of >1 day) during quiet conditions with typical wave amplitudes of tenths of mV/m. However, for the low-energy (˜100 eV to below 2 keV) electron population mainly associated with the diffuse auroral emission, ECH waves are only responsible for rapid pitch angle diffusion (occasionally near the limit of strong diffusion) for a small portion of the electron population with pitch angles αeq 70°. Computations of the bounce-averaged coefficients of momentum diffusion and (pitch angle, momentum) mixed diffusion indicate that both mixed diffusion and energy diffusion of plasma sheet electrons due to ECH waves are very small compared to pitch angle diffusion and that ECH waves have little effect on local electron acceleration. Consequently, the multiple harmonic ECH emissions cannot play a dominant role in the occurrence of diffuse auroral precipitation near L = 6, and other wave-particle interaction mechanisms, such as whistler mode chorus-driven resonant scattering, are required to explain the global distribution of diffuse auroral precipitation and the formation of the pancake distribution in the inner magnetosphere.
Coherent structures and transport in drift wave plasma turbulence
Korsholm, Søren Bang
for optimization. The present work is a part of the puzzle to understand the basic physics of transport induced by drift wave turbulence in the edge region of a plasma. The basis for the study is the Hasegawa- Wakatani model. Simulation results for 3D periodic and nonperiodic geometries are presented. The Hasegawa......-Wakatani model is further expanded to include ion temperature effects. Another expansion of the model is derived from the Braginskii electron temperature equation. The result is a self-consistent set of equations describing the dynamical evolution of the drift wave fluctuations of the electron density, electron......Fusion energy research aims at developing fusion power plants providing safe and clean energy with abundant fuels. Plasma turbulence induced transport of energy and particles is a performance limiting factor for fusion devices. Hence the understanding of plasma turbulence is important...
3D elastic full-waveform inversion for OBC data using the P-wave excitation amplitude
Oh, Ju-Won
2017-08-17
We suggest a fast and efficient 3D elastic full waveform inversion (FWI) algorithm based on the excitation amplitude (maximum energy arrival) of the P-wave in the source wavefield. It evaluates the gradient direction significantly faster than its conventional counterpart. In addition, it removes the long-wavelength artifacts from the gradient, which are often originated from SS correlation process. From these advantages, the excitation approach offers faster convergence not only for the S wave velocity, but also for the entire process of multi-parameter inversion, compared to the conventional FWI. The feasibility of the proposed method is demonstrated through the synthetic Marmousi and a real OBC data from North Sea.
Helicon waves in uniform plasmas. II. High m numbers
Stenzel, R. L.; Urrutia, J. M. [Department of Physics and Astronomy, University of California, Los Angeles, California 90095-1547 (United States)
2015-09-15
Helicons are whistler modes with azimuthal wave numbers. They have been studied in solids and plasmas where boundaries play a role. The present work shows that very similar modes exist in unbounded gaseous plasmas. Instead of boundaries, the antenna properties determine the topology of the wave packets. The simplest antenna is a magnetic loop which excites m = 0 or m = 1 helicons depending on whether the dipole moment is aligned parallel or perpendicular to the ambient background magnetic field B{sub 0}. While these low order helicons have been described by J. M. Urrutia and R. L. Stenzel [“Helicon modes in uniform plasmas. I. Low m modes,” Phys. Plasmas 22, 092111 (2015)], the present work focuses on high order modes up to m = 8. These are excited by antenna arrays forming magnetic multipoles. Their wave magnetic field has been measured in space and time in a large and uniform laboratory plasma free of boundary effects. The observed wave topology exhibits m pairs of unique field line spirals which may have inspired the name “helicon” to this mode. All field lines converge into these nested spirals which propagate like corkscrews along B{sub 0}. The field lines near the axis of helicons are perpendicular to B{sub 0} and circularly polarized as in parallel whistlers. Helical antennas couple to these transverse fields but not to the spiral fields of helicons. Using a circular antenna array of phased m = 0 loops, right or left rotating or non-rotating multipole antenna fields are generated. They excite m < 0 and m > 0 modes, showing that the plasma supports both modes equally well. The poor excitation of m < 0 modes is a characteristic of loops with dipole moment across B{sub 0}. The radiation efficiency of multipole antennas has been found to decrease with m.
Bernstein wave aided laser third harmonic generation in a plasma
Tyagi, Yachna; Tripathi, Deepak; Kumar, Ashok
2016-09-01
The process of Bernstein wave aided resonant third harmonic generation of laser in a magnetized plasma is investigated. The extra-ordinary mode (X-mode) laser of frequency ω 0 and wave number k → 0 , travelling across the magnetic field in a plasma, exerts a second harmonic ponderomotive force on the electrons imparting them an oscillatory velocity v → 2 ω0 , 2 k → 0 . This velocity beats with the density perturbation due to the Bernstein wave to produce a density perturbation at cyclotron frequency shifted second harmonic. The density perturbation couples with the oscillatory velocity v → ω0 , k → 0 of X-mode of the laser to produce the cyclotron frequency shifted third harmonic current density leading to harmonic radiation. The phase matching condition for the up shifted frequency is satisfied when the Bernstein wave is nearly counter-propagating to the laser. As the transverse wave number of the Bernstein wave is large, it is effective in the phase matched third harmonic generation, when the laser frequency is not too far from the upper hybrid frequency.
Kinetic Simulations of the Self-Focusing and Dissipation of Finite-Width Electron Plasma Waves
Winjum, B. J. [Univ. of California, Los Angeles, CA (United States); Berger, R. L. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Chapman, T. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Banks, J. W. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Brunner, S. [Federal Inst. of Technology, Lausanne (Switzerland)
2013-09-01
Two-dimensional simulations, both Vlasov and particle-in-cell, are presented that show the evolution of the field and electron distribution of finite-width, nonlinear electron plasma waves. The intrinsically intertwined effects of self-focusing and dissipation of field energy caused by electron trapping are studied in simulated systems that are hundreds of wavelengths long in the transverse direction but only one wavelength long and periodic in the propagation direction. From various initial wave states, both the width at focus Δm relative to the initial width Δ0 and the maximum field amplitude at focus are shown to be a function of the growth rate of the transverse modulational instability γ_{TPMI} divided by the loss rate of field energy ν_{E} to electrons escaping the trapping region. With dissipation included, an amplitude threshold for self-focusing γ_{TPMI}/ν_{E}~1 is found that supports the analysis of Rose [Phys. Plasmas 12, 012318 (2005)].
Koons, H. C.; Roeder, J. L.; Bauer, O. H.; Haerendel, G.; Treumann, R.
1987-01-01
Nonlinear wave decay processes have been detected in the solar wind by the plasma wave experiment aboard the Active Magnetospheric Particle Tracer Explorers (AMPTE) IRM spacecraft. The main process is the generation of ultralow-frequency ion acoustic waves from the decay of Langmuir waves near the electron plasma frequency. Frequently, this is accompanied by an enhancement of emissions near twice the plasma frequency. This enhancement is most likely due to the generation of electromagnetic waves from the coalescence of two Langmuir waves. These processes occur within the electron foreshock in front of the earth's bow shock.
Potential role of kinetic Alfvén waves and whistler waves in solar wind plasmas
Nandal, P.; Yadav, N.; Sharma, R. P.; Goldstein, M. L.
2016-07-01
Spacecraft observations indicate the signatures of highly oblique kinetic Alfvén waves (KAWs) and whistler waves in the solar wind plasma. In the present work, we explore the possible role of KAWs and whistler waves in the observed solar wind magnetic turbulent spectrum. The nonlinear spatial evolution of KAW is studied including the effects of the ponderomotive force which results in intense localized structures due to the background density modification. Weak quasi-transverse whistler wave propagating through these localized structures also gets localized in the form of small-scale localized structures. We present numerically calculated magnetic power spectra for both KAW as well as for whistler wave. Our obtained results demonstrate the important role that KAWs and whistler waves play in the energy cascading from larger to smaller scales. The relevance of these results to recent spacecraft observations is also pointed out.
Sparrow, Victor Ward
1990-01-01
This study has concerned the propagation of finite amplitude, i.e. weakly non-linear, acoustical blast waves from explosions over hard and porous media models of outdoor ground surfaces. The nonlinear acoustic propagation effects require a numerical solution in the time domain. To model a porous ground surface, which in the frequency domain exhibits a finite impedance, the linear phenomenological porous model of Morse and Ingard was used. The phenomenological equations are solved in the time domain for coupling with the time domain propagation solution in the air. The numerical solution is found through the method of finite differences. The second-order in time and fourth -order in space MacCormack method was used in the air, and the second-order in time and space MacCormack method was used in the porous medium modeling the ground. Two kinds of numerical absorbing boundary conditions were developed for the air propagation equations to truncate the physical domain for solution on a computer. Radiation conditions first were used on those sides of the domain where there were outgoing waves. Characteristic boundary conditions secondly are employed near the acoustic source. The numerical model agreed well with the Pestorius algorithm for the propagation of electric spark pulses in the free field, and with a result of Pfriem for normal plane reflection off a hard surface. In addition, curves of pressure amplification versus incident angle for waves obliquely incident on the hard and porous surfaces were produced which are similar to those in the literature. The model predicted that near grazing finite amplitude acoustic blast waves decay with distance over hard surfaces as r to the power -1.2. This result is consistent with the work of Reed. For propagation over the porous ground surface, the model predicted that this surface decreased the decay rate with distance for the larger blasts compared to the rate expected in the linear acoustics limit.
Non-resonant interacting ion acoustic waves in a magnetized plasma
Maccari, Attilio [Technical Institute ' G Cardano' , Monterotondo, Rome (Italy)
1999-01-29
We perform an analytical and numerical investigation of the interaction among non-resonant ion acoustic waves in a magnetized plasma. Waves are supposed to be non-resonant, i.e. with different group velocities that are not close to each other. We use an asymptotic perturbation method, based on Fourier expansion and spatio-temporal rescaling. We show that the amplitude slow modulation of Fourier modes cannot be described by the usual nonlinear Schroedinger equation but by a new model system of nonlinear evolution equations. This system is C-integrable, i.e. it can be linearized through an appropriate transformation of the dependent and independent variables. We demonstrate that a subclass of solutions gives rise to envelope solitons. Each envelope soliton propagates with its own group velocity. During a collision solitons maintain their shape, the only change being a phase shift. Numerical results are used to check the validity of the asymptotic perturbation method. (author)
Analysis of plasma waves observed in the inner Saturn magnetosphere
J. D. Menietti
2008-09-01
Full Text Available Plasma waves observed in the Saturn magnetosphere provide an indication of the plasma population present in the rotationally dominated inner magnetosphere. Electrostatic cyclotron emissions often with harmonics and whistler mode emission are a common feature of Saturn's inner magnetosphere. The electron observations for a region near 5 R_{S} outside and near a plasma injection region indicate a cooler low-energy (<100 eV, nearly isotropic plasma, and a much warmer (E>1000 eV more pancake or butterfly distribution. We model the electron plasma distributions to conduct a linear dispersion analysis of the wave modes. The results suggest that the electrostatic electron cyclotron emissions can be generated by phase space density gradients associated with a loss cone that may be up to 20° wide. This loss cone is sometimes, but not always, observed because the field of view of the electron detectors does not include the magnetic field line at the time of the observations. The whistler mode emission can be generated by the pancake-like distribution and temperature anisotropy (T_{⊥}/T_{||}>1 of the warmer plasma population.
Cylindrical and spherical positron-acoustic shock waves in nonthermal electron-positron-ion plasmas
Rahman, M.M.; Alam, M.S.; Mamun, A.A., E-mail: shohelplasma@gmail.com [Department of Physics, Jahangirnagar University, Savar, Dhaka (Bangladesh)
2015-06-15
The nonlinear propagation of cylindrical and spherical positron-acoustic shock waves (PASWs) in an unmagnetized four-component plasma (containing nonthermal distributed hot positrons and electrons, cold mobile viscous positron fluid, and immobile positive ions) is investigated theoretically. The modified Burgers equation is derived by employing the reductive perturbation method. Analytically, the effects of cylindrical and spherical geometries, nonthermality of electrons and hot positrons, relative number density and temperature ratios, and cold mobile positron kinematic viscosity on the basic features (viz. polarity, amplitude, width, phase speed, etc.) of PASWs are briefly addressed. It is examined that the PASWs in nonplanar (cylindrical and spherical) geometry significantly differ from those in planar geometry. The relevance of our results may be useful in understanding the basic characteristics of PASWs in astrophysical and laboratory plasmas. (author)
Raicharan Denra
2016-12-01
Full Text Available In this paper, characteristics of small amplitude nonlinear dust acoustic wave have been investigated in a unmagnetized, collisionless, Lorentzian dusty plasma where electrons and ions are inertialess and modeled by generalized Lorentzian Kappa distribution. Dust grains are inertial and equilibrium dust charge is negative. Both adiabatic and nonadiabatic fluctuation of charges on dust grains have been taken under consideration. For adiabatic dust charge variation reductive perturbation analysis gives rise to a KdV equation that governs the nonlinear propagation of dust acoustic waves having soliton solutions. For nonadiabatic dust charge variation nonlinear propagation of dust acoustic wave obeys KdV-Burger equation and gives rise to dust acoustic shock waves. Numerical estimation for adiabatic grain charge variation shows the existence of rarefied soliton whose amplitude and width varies with grain charges. Amplitude and width of the soliton have been plotted for different electron Kappa indices keeping ion velocity distribution Maxwellian. For non adiabatic dust charge variation, ratio of the coefficients of Burger term and dispersion term have been plotted against charge fluctuation for different kappa indices. All these results approach to the results of Maxwellian plasma if both electron and ion kappa tends to infinity.
Denra, Raicharan; Paul, Samit; Sarkar, Susmita
2016-12-01
In this paper, characteristics of small amplitude nonlinear dust acoustic wave have been investigated in a unmagnetized, collisionless, Lorentzian dusty plasma where electrons and ions are inertialess and modeled by generalized Lorentzian Kappa distribution. Dust grains are inertial and equilibrium dust charge is negative. Both adiabatic and nonadiabatic fluctuation of charges on dust grains have been taken under consideration. For adiabatic dust charge variation reductive perturbation analysis gives rise to a KdV equation that governs the nonlinear propagation of dust acoustic waves having soliton solutions. For nonadiabatic dust charge variation nonlinear propagation of dust acoustic wave obeys KdV-Burger equation and gives rise to dust acoustic shock waves. Numerical estimation for adiabatic grain charge variation shows the existence of rarefied soliton whose amplitude and width varies with grain charges. Amplitude and width of the soliton have been plotted for different electron Kappa indices keeping ion velocity distribution Maxwellian. For non adiabatic dust charge variation, ratio of the coefficients of Burger term and dispersion term have been plotted against charge fluctuation for different kappa indices. All these results approach to the results of Maxwellian plasma if both electron and ion kappa tends to infinity.
Scanning tunneling microscopy in TTF-TCNQ: Phase and amplitude modulated charge density waves
Wang, Z.Z.; Gorard, J.C.; Pasquier, C.
2003-01-01
Charge density waves (CDWs) have been studied at the surface of a cleaved tetrathiafulvalene-tetracyanoquinodimethane (TTF-TCNQ) single crystal using a low temperature scanning tunneling microscope (STM) under ultrahigh-vacuum conditions, between 300 and 33 K with molecular resolution. All CDW...