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Sample records for arbitrary amplitude ion-acoustic

  1. Arbitrary amplitude quantum dust ion-acoustic solitary waves

    SciTech Connect

    Tribeche, Mouloud; Ghebache, Siham; Aoutou, Kamel; Zerguini, Taha Houssine

    2008-03-15

    The one-dimensional quantum hydrodynamic model for a three-species quantum plasma is used to study the quantum counterpart of the well known dust ion-acoustic (DIA) wave. Two cases of physical interest are investigated, namely positive and negative dust charge. It is shown that only rarefactive solitary potentials associated with nonlinear quantum DIA (QDIA) waves involving electron density deeps can exist. The QDIA soliton experiences a spreading and the quantum effects tend to make it wider. Under certain conditions, the soliton enlarges and its pulse shape evolves into a broad central flat-bottomed (or table-bottomed) soliton as a limiting-amplitude member of the QDIA soliton family. Linear stability analysis as well as quasineutral solutions are succinctly outlined. The investigation could be of relevance to astrophysical quantum dusty plasmas.

  2. Arbitrary amplitude quantum dust ion-acoustic solitary waves

    NASA Astrophysics Data System (ADS)

    Tribeche, Mouloud; Ghebache, Siham; Aoutou, Kamel; Zerguini, Taha Houssine

    2008-03-01

    The one-dimensional quantum hydrodynamic model for a three-species quantum plasma is used to study the quantum counterpart of the well known dust ion-acoustic (DIA) wave. Two cases of physical interest are investigated, namely positive and negative dust charge. It is shown that only rarefactive solitary potentials associated with nonlinear quantum DIA (QDIA) waves involving electron density deeps can exist. The QDIA soliton experiences a spreading and the quantum effects tend to make it wider. Under certain conditions, the soliton enlarges and its pulse shape evolves into a broad central flat-bottomed (or table-bottomed) soliton as a limiting-amplitude member of the QDIA soliton family. Linear stability analysis as well as quasineutral solutions are succinctly outlined. The investigation could be of relevance to astrophysical quantum dusty plasmas.

  3. Arbitrary amplitude ion-acoustic waves in a multicomponent plasma with superthermal species

    SciTech Connect

    El-Tantawy, S. A.; Moslem, W. M.

    2011-11-15

    Properties of fully nonlinear ion-acoustic waves in a multicomponent plasma consisting of warm positive ions, superthermal electrons, as well as positrons, and dust impurities have been investigated. By using the hydrodynamic model for ions and superthermal electron/positron distribution, a Sagdeev potential has been derived. Existence conditions for large amplitude solitary and shock waves are presented. In order to show that the characteristics of the solitary and shock waves are influenced by the plasma parameters, the relevant numerical analysis of the Sagdeev potential is presented. The nonlinear structures, as predicted here, may be associated with the electrostatic perturbations in interstellar medium.

  4. Effect of ion temperature on arbitrary amplitude ion acoustic solitary waves in quantum electron-ion plasmas

    NASA Astrophysics Data System (ADS)

    Chatterjee, Prasanta; Roy, Kaushik; Muniandy, Sithi V.; Yap, S. L.; Wong, C. S.

    2009-04-01

    Using Sagdeev's pseudopotential technique, the effect of ion temperature on the arbitrary amplitude ion acoustic solitary waves in quantum electron-ion plasma is studied. In addition, the effect of ion temperature on the region of existence, as well as on the shape of the solitary waves, is also investigated extensively. It is shown that for large amplitude solitary wave, quantum parameter H does not play any role in determining the region of existence and on the amplitude of the solitary waves. However, H has a significant effect on the width of the solitary wave. It is worth noting that our results are in agreement with previous investigations when the effect of ion temperature is neglected.

  5. Existence domains of arbitrary amplitude nonlinear structures in two-electron temperature space plasmas. I. Low-frequency ion-acoustic solitons

    SciTech Connect

    Maharaj, S. K.; Bharuthram, R.; Singh, S. V.; Lakhina, G. S.

    2012-07-15

    Using the Sagdeev pseudopotential technique, the existence of large amplitude ion-acoustic solitons is investigated for a plasma composed of ions, and hot and cool electrons. Not only are all species treated as adiabatic fluids but the model for which inertial effects of the hot electrons is neglected whilst retaining inertia and pressure for the ions and cool electrons has also been considered. The focus of this investigation has been on identifying the admissible Mach number ranges for large amplitude nonlinear ion-acoustic soliton structures. The lower Mach number limit yields a minimum velocity for the existence of ion-acoustic solitons. The upper Mach number limit for positive potential solitons is found to coincide with the limiting value of the potential (positive) beyond which the ion number density ceases to be real valued, and ion-acoustic solitons can no longer exist. Small amplitude solitons having negative potentials are found to be supported when the temperature of the cool electrons is negligible.

  6. Propagation of arbitrary amplitude dust-ion acoustic waves in the collisional magnetized dusty plasma in the presence of non-thermal electrons

    NASA Astrophysics Data System (ADS)

    Sayyar, M.; Zahed, H.; Pestehe, S. J.; Sobhanian, S.

    2016-07-01

    Using the Sagdeev pseudo-potential method, the oblique propagation of dust-ion acoustic solitary waves is studied in a magnetized dusty plasma. By considering non-thermal distribution of electrons, the related pseudo-potential is obtained using the Poisson equation. The behavior of the wave is investigated for some ranges of parameters. It is demonstrated that the increase in ion density, lz, β, and also δ1 can lead to the increases in the width and amplitude of the pseudo-potential, while any increase of a2, the coefficient that describes the first nonlinear term in the G ( ϕ ) , increases the amplitude of the V ( ϕ ) .

  7. Large amplitude ion-acoustic solitons in dusty plasmas

    NASA Astrophysics Data System (ADS)

    Tiwari, R. S.; Jain, S. L.; Mishra, M. K.

    2011-08-01

    Characteristics of ion-acoustic soliton in dusty plasma, including the dynamics of heavily charged massive dust grains, are investigated following the Sagdeev Potential formalism. Retaining fourth order nonlinearities of electric potential in the expansion of the Sagdeev Potential in the energy equation for a pseudo particle and integrating the resulting energy equation, large amplitude soliton solution is determined. Variation of amplitude (A), half width (W) at half maxima and the product P = AW2 of the Korteweg-deVries (KdV), dressed and large amplitude soliton as a function of wide range of dust concentration are numerically studied for recently observed parameters of dusty plasmas. We have also presented the region of existence of large amplitude ion-acoustic soliton in the dusty plasma by analyzing the structure of the pseudo potential. It is found that in the presence of positively charged dust grains, system supports only compressive solitons, on the other hand, in the presence of negatively charged dust grains, the system supports compressive solitons up to certain critical concentration of dust grains and above this critical concentration, the system can support rarefactive solitons also. The effects of dust concentration, charge, and mass of the dust grains, on the characteristics of KdV, dressed and large amplitude the soliton, i.e., amplitude (A), half width at half maxima (W), and product of amplitude (A) and half width at half maxima (P = AW2), are discussed in detail

  8. Large amplitude ion-acoustic solitons in dusty plasmas

    SciTech Connect

    Tiwari, R. S.; Jain, S. L.; Mishra, M. K.

    2011-08-15

    Characteristics of ion-acoustic soliton in dusty plasma, including the dynamics of heavily charged massive dust grains, are investigated following the Sagdeev Potential formalism. Retaining fourth order nonlinearities of electric potential in the expansion of the Sagdeev Potential in the energy equation for a pseudo particle and integrating the resulting energy equation, large amplitude soliton solution is determined. Variation of amplitude (A), half width (W) at half maxima and the product P = AW{sup 2} of the Korteweg-deVries (KdV), dressed and large amplitude soliton as a function of wide range of dust concentration are numerically studied for recently observed parameters of dusty plasmas. We have also presented the region of existence of large amplitude ion-acoustic soliton in the dusty plasma by analyzing the structure of the pseudo potential. It is found that in the presence of positively charged dust grains, system supports only compressive solitons, on the other hand, in the presence of negatively charged dust grains, the system supports compressive solitons up to certain critical concentration of dust grains and above this critical concentration, the system can support rarefactive solitons also. The effects of dust concentration, charge, and mass of the dust grains, on the characteristics of KdV, dressed and large amplitude the soliton, i.e., amplitude (A), half width at half maxima (W), and product of amplitude (A) and half width at half maxima (P = AW{sup 2}), are discussed in detail.

  9. Nonlinear ion-acoustic solitons in a magnetized quantum plasma with arbitrary degeneracy of electrons

    NASA Astrophysics Data System (ADS)

    Haas, Fernando; Mahmood, Shahzad

    2016-09-01

    Nonlinear ion-acoustic waves are analyzed in a nonrelativistic magnetized quantum plasma with arbitrary degeneracy of electrons. Quantum statistics is taken into account by means of the equation of state for ideal fermions at arbitrary temperature. Quantum diffraction is described by a modified Bohm potential consistent with finite-temperature quantum kinetic theory in the long-wavelength limit. The dispersion relation of the obliquely propagating electrostatic waves in magnetized quantum plasma with arbitrary degeneracy of electrons is obtained. Using the reductive perturbation method, the corresponding Zakharov-Kuznetsov equation is derived, describing obliquely propagating two-dimensional ion-acoustic solitons in a magnetized quantum plasma with degenerate electrons having an arbitrary electron temperature. It is found that in the dilute plasma case only electrostatic potential hump structures are possible, while in dense quantum plasma, in principle, both hump and dip soliton structures are obtainable, depending on the electron plasma density and its temperature. The results are validated by comparison with the quantum hydrodynamic model including electron inertia and magnetization effects. Suitable physical parameters for observations are identified.

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

    NASA Astrophysics Data System (ADS)

    Haas, Fernando; Mahmood, Shahzad

    2015-11-01

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

  11. Arbitrary Amplitude DIA and DA Solitary Waves in Adiabatic Dusty Plasmas

    SciTech Connect

    Mamun, A. A.; Jahan, N.; Shukla, P. K.

    2008-10-15

    The dust-ion-acoustic (DIA) as well as the dust-acoustic (DA) solitary waves (SWs) in an adiabatic dusty plasma are investigated by the pseudo-potential approach which is valid for arbitrary amplitude SWs. The role of the adiabaticity of electrons and ions in modifying the basic features (polarity, speed, amplitude and width) of arbitrary amplitude DIA and DA SWs are explicitly examined. It is found that the effects of the adiabaticity of electrons and ions significantly modify the basic features (polarity, speed, amplitude and width) of the DIA and DA SWs. The implications of our results in space and laboratory dusty plasmas are briefly discussed.

  12. Particle-in-cell simulation of large amplitude ion-acoustic solitons

    SciTech Connect

    Sharma, Sarveshwar Sengupta, Sudip; Sen, Abhijit

    2015-02-15

    The propagation of large amplitude ion-acoustic solitons is studied in the laboratory frame (x, t) using a 1-D particle-in-cell code that evolves the ion dynamics by treating them as particles but assumes the electrons to follow the usual Boltzmann distribution. It is observed that for very low Mach numbers the simulation results closely match the Korteweg-de Vries soliton solutions, obtained in the wave frame, and which propagate without distortion. The collision of two such profiles is observed to exhibit the usual solitonic behaviour. As the Mach number is increased, the given profile initially evolves and then settles down to the exact solution of the full non-linear Poisson equation, which then subsequently propagates without distortion. The fractional change in amplitude is found to increase linearly with Mach number. It is further observed that initial profiles satisfying k{sup 2}λ{sub de}{sup 2}<1 break up into a series of solitons.

  13. Effect of excess superthermal hot electrons on finite amplitude ion-acoustic solitons and supersolitons in a magnetized auroral plasma

    SciTech Connect

    Rufai, O. R.; Bharuthram, R.; Singh, S. V. Lakhina, G. S.

    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.

  14. Effect of excess superthermal hot electrons on finite amplitude ion-acoustic solitons and supersolitons in a magnetized auroral plasma

    NASA Astrophysics Data System (ADS)

    Rufai, O. R.; Bharuthram, R.; Singh, S. V.; Lakhina, G. S.

    2015-10-01

    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.

  15. Amplitude modulation of quantum-ion-acoustic wavepackets in electron-positron-ion plasmas: Modulational instability, envelope modes, extreme wavesa)

    NASA Astrophysics Data System (ADS)

    Rahman, Ata-ur-; Kerr, Michael Mc; El-Taibany, Wael F.; Kourakis, Ioannis; Qamar, A.

    2015-02-01

    A semirelativistic fluid model is employed to describe the nonlinear amplitude modulation of low-frequency (ionic scale) electrostatic waves in an unmagnetized electron-positron-ion plasma. Electrons and positrons are assumed to be degenerated and inertialess, whereas ions are warm and classical. A multiscale perturbation method is used to derive a nonlinear Schrödinger equation for the envelope amplitude, based on which the occurrence of modulational instability is investigated in detail. Various types of localized ion acoustic excitations are shown to exist, in the form of either bright type envelope solitons (envelope pulses) or dark-type envelope solitons (voids, holes). The plasma configurational parameters (namely, the relativistic degeneracy parameter, the positron concentration, and the ionic temperature) are shown to affect the conditions for modulational instability significantly, in fact modifying the associated threshold as well as the instability growth rate. In particular, the relativistic degeneracy parameter leads to an enhancement of the modulational instability mechanism. Furthermore, the effect of different relevant plasma parameters on the characteristics (amplitude, width) of these envelope solitary structures is also presented in detail. Finally, the occurrence of extreme amplitude excitation (rogue waves) is also discussed briefly. Our results aim at elucidating the formation and dynamics of nonlinear electrostatic excitations in superdense astrophysical regimes.

  16. Amplitude modulation of quantum-ion-acoustic wavepackets in electron-positron-ion plasmas: Modulational instability, envelope modes, extreme waves

    SciTech Connect

    Rahman, Ata-ur-; Kerr, Michael Mc Kourakis, Ioannis; El-Taibany, Wael F.; Qamar, A.

    2015-02-15

    A semirelativistic fluid model is employed to describe the nonlinear amplitude modulation of low-frequency (ionic scale) electrostatic waves in an unmagnetized electron-positron-ion plasma. Electrons and positrons are assumed to be degenerated and inertialess, whereas ions are warm and classical. A multiscale perturbation method is used to derive a nonlinear Schrödinger equation for the envelope amplitude, based on which the occurrence of modulational instability is investigated in detail. Various types of localized ion acoustic excitations are shown to exist, in the form of either bright type envelope solitons (envelope pulses) or dark-type envelope solitons (voids, holes). The plasma configurational parameters (namely, the relativistic degeneracy parameter, the positron concentration, and the ionic temperature) are shown to affect the conditions for modulational instability significantly, in fact modifying the associated threshold as well as the instability growth rate. In particular, the relativistic degeneracy parameter leads to an enhancement of the modulational instability mechanism. Furthermore, the effect of different relevant plasma parameters on the characteristics (amplitude, width) of these envelope solitary structures is also presented in detail. Finally, the occurrence of extreme amplitude excitation (rogue waves) is also discussed briefly. Our results aim at elucidating the formation and dynamics of nonlinear electrostatic excitations in superdense astrophysical regimes.

  17. Quasi-periodic behavior of ion acoustic solitary waves in electron-ion quantum plasma

    NASA Astrophysics Data System (ADS)

    Sahu, Biswajit; Poria, Swarup; Narayan Ghosh, Uday; Roychoudhury, Rajkumar

    2012-05-01

    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.

  18. Arbitrary amplitude solitary and shock waves in an unmagnetized quantum dusty electron-positron-ion plasma

    NASA Astrophysics Data System (ADS)

    Rouhani, M. R.; Akbarian, A.; Mohammadi, Z.

    2013-08-01

    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.

  19. Arbitrary amplitude solitary and shock waves in an unmagnetized quantum dusty electron-positron-ion plasma

    SciTech Connect

    Rouhani, M. R.; Akbarian, A.; Mohammadi, Z.

    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.

  20. Small amplitude dust ion-acoustic solitary waves and double layers in a dusty plasma with flat-topped electron distribution

    SciTech Connect

    Alinejad, H.; Mamun, A. A.

    2010-12-15

    The properties of small but finite amplitude dust ion-acoustic (DIA) solitary waves (SWs) as well double layers (DLs) in a dusty plasma containing warm adiabatic ions, electrons following flat-topped velocity distribution, and arbitrarily (positively or negatively) charged immobile dust are studied. The effects of ion-temperature, resonant electrons, and dust number density are found to significantly modify the criteria for the existence of the DIA SWs and DLs, as well as significantly modify their basic features. It is also shown that the ion-temperature reduces the possibility for the formation of these localized structures, and that their amplitude decreases (increases) with the increase in the negative (positive) dust number density.

  1. Arbitrary amplitude electrostatic wave propagation in a magnetized dense plasma containing helium ions and degenerate electrons

    NASA Astrophysics Data System (ADS)

    Mahmood, S.; Sadiq, Safeer; Haque, Q.; Ali, Munazza Z.

    2016-06-01

    The obliquely propagating arbitrary amplitude electrostatic wave is studied in a dense magnetized plasma having singly and doubly charged helium ions with nonrelativistic and ultrarelativistic degenerate electrons pressures. The Fermi temperature for ultrarelativistic degenerate electrons described by N. M. Vernet [(Cambridge University Press, Cambridge, 2007), p. 57] is used to define ion acoustic speed in ultra-dense plasmas. The pseudo-potential approach is used to solve the fully nonlinear set of dynamic equations for obliquely propagating electrostatic waves in a dense magnetized plasma containing helium ions. The upper and lower Mach number ranges for the existence of electrostatic solitons are found which depends on the obliqueness of the wave propagation with respect to applied magnetic field and charge number of the helium ions. It is found that only compressive (hump) soliton structures are formed in all the cases and only subsonic solitons are formed for a singly charged helium ions plasma case with nonrelativistic degenerate electrons. Both subsonic and supersonic soliton hump structures are formed for doubly charged helium ions with nonrelativistic degenerate electrons and ultrarelativistic degenerate electrons plasma case containing singly as well as doubly charged helium ions. The effect of propagation direction on the soliton amplitude and width of the electrostatic waves is also presented. The numerical plots are also shown for illustration using dense plasma parameters of a compact star (white dwarf) from literature.

  2. Ion acoustic traveling waves

    NASA Astrophysics Data System (ADS)

    Webb, G. M.; Burrows, R. H.; Ao, X.; Zank, G. P.; Zank

    2014-04-01

    Models for traveling waves in multi-fluid plasmas give essential insight into fully nonlinear wave structures in plasmas, not readily available from either numerical simulations or from weakly nonlinear wave theories. We illustrate these ideas using one of the simplest models of an electron-proton multi-fluid plasma for the case where there is no magnetic field or a constant normal magnetic field present. We show that the traveling waves can be reduced to a single first-order differential equation governing the dynamics. We also show that the equations admit a multi-symplectic Hamiltonian formulation in which both the space and time variables can act as the evolution variable. An integral equation useful for calculating adiabatic, electrostatic solitary wave signatures for multi-fluid plasmas with arbitrary mass ratios is presented. The integral equation arises naturally from a fluid dynamics approach for a two fluid plasma, with a given mass ratio of the two species (e.g. the plasma could be an electron-proton or an electron-positron plasma). Besides its intrinsic interest, the integral equation solution provides a useful analytical test for numerical codes that include a proton-electron mass ratio as a fundamental constant, such as for particle in cell (PIC) codes. The integral equation is used to delineate the physical characteristics of ion acoustic traveling waves consisting of hot electron and cold proton fluids.

  3. Arbitrary amplitude double layers in warm dust kinetic Alfven wave plasmas

    SciTech Connect

    Gogoi, Runmoni; Devi, Nirupama

    2008-07-15

    Large amplitude electrostatic structures associated with low-frequency dust kinetic Alfvenic waves are investigated under the pressure (temperature) gradient indicative of dust dynamics. The set of equations governing the dust dynamics, Boltzmann electrons, ions and Maxwell's equation have been reduced to a single equation known as the Sagdeev potential equation. Parameter ranges for the existence of arbitrary amplitude double layers are observed. Exact analytical expressions for the energy integral is obtained and computed numerically through which sub-Alfvenic arbitrary amplitude rarefactive double layers are found to exist.

  4. Nonlinear features of ion acoustic shock waves in dissipative magnetized dusty plasma

    SciTech Connect

    Sahu, Biswajit; Sinha, Anjana; Roychoudhury, Rajkumar

    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.

  5. Oblique Propagation of Ion Acoustic Solitons in Magnetized Superthermal Plasmas

    NASA Astrophysics Data System (ADS)

    Devanandhan, S.; Sreeraj, T.; Singh, S.; Lakhina, G. S.

    2015-12-01

    Small amplitude ion-acoustic solitons are studied in a magnetized plasma consisting of protons, doubly charged helium ions and superthermal electrons. The Korteweg-de-Vries-Zakharov-Kuznetsov (KdV-ZK) is derived to examine the properties of ion acoustic solitary structures observed in space plasmas. Our model is applicable for weakly magnetized plasmas. The results will be applied to the satellite observations in the solar wind at 1 AU where magnetized ion acoustic waves with superthermal electrons can exist. The effects of superthermality, temperature and densities on these solitary structures will be discussed.

  6. Dust ion acoustic solitons in a plasma with kappa-distributed electrons

    SciTech Connect

    Baluku, T. K.; Hellberg, M. A.; Kourakis, I.; Saini, N. S.

    2010-05-15

    Dust ion acoustic solitons in an unmagnetized dusty plasma comprising cold dust particles, adiabatic fluid ions, and electrons satisfying a kappa distribution are investigated using both small amplitude and arbitrary amplitude techniques. Their existence domain is discussed in the parameter space of Mach number M and electron density fraction f over a wide range of values of kappa. For all kappa>3/2, including the Maxwellian distribution, negative dust supports solitons of both polarities over a range in f. In that region of parameter space solitary structures of finite amplitude can be obtained even at the lowest Mach number, the acoustic speed, for all kappa. These cannot be found from small amplitude theories. This surprising behavior is investigated, and it is shown that f{sub c}, the value of f at which the KdV coefficient A vanishes, plays a critical role. In the presence of positive dust, only positive potential solitons are found.

  7. Sagdeev potential approach for quantum ion-acoustic solitary waves in an electron-positron-ion plasma

    NASA Astrophysics Data System (ADS)

    Banerjee, Gadadhar; Maitra, Sarit

    2016-06-01

    Sagdeev pseudopotential method is employed to study the arbitrary amplitude quantum ion-acoustic solitary waves in an unmagnetized electron-positron-ion plasma by using one dimensional quantum hydrodynamic model together with the Poisson equation. Sagdeev potential function is obtained in terms of electrostatic potential and analyzed with and without the effect of quantum diffraction parameter H. Effects of the parameter H on both the amplitude and width of the solitary waves have been observed. It is also observed that the positron density can affect the wave propagation.

  8. Ion-acoustic cnoidal waves in a quantum plasma

    SciTech Connect

    Mahmood, S.; Haas, F.

    2014-10-15

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

  9. Arbitrary manipulation of spatial amplitude and phase using phase-only spatial light modulators

    PubMed Central

    Zhu, Long; Wang, Jian

    2014-01-01

    Spatial structure of a light beam is an important degree of freedom to be extensively explored. By designing simple configurations with phase-only spatial light modulators (SLMs), we show the ability to arbitrarily manipulate the spatial full field information (i.e. amplitude and phase) of a light beam. Using this approach to facilitating arbitrary and independent control of spatial amplitude and phase, one can flexibly generate different special kinds of light beams for different specific applications. Multiple collinear orbital angular momentum (OAM) beams, Laguerre-Gaussian (LG) beams, and Bessel beams, having both spatial amplitude and phase distributions, are successfully generated in the experiments. Some arbitrary beams with odd-shaped intensity are also generated in the experiments. PMID:25501584

  10. Nonlinear propagation of ion-acoustic waves in electron-positron-ion plasma with trapped electrons

    NASA Astrophysics Data System (ADS)

    Alinejad, H.; Sobhanian, S.; Mahmoodi, J.

    2006-01-01

    A theoretical investigation has been made for ion-acoustic waves in an unmagnetized electron-positron-ion plasma. A more realistic situation in which plasma consists of a negatively charged ion fluid, free positrons, and trapped as well as free electrons is considered. The properties of stationary structures are studied by the reductive perturbation method, which is valid for small but finite amplitude limit, and by pseudopotential approach, which is valid for large amplitude. With an appropriate modified form of the electron number density, two new equations for the ion dynamics have been found. When deviations from isothermality are finite, the modified Korteweg-deVries equation has been found, and for the case that deviations from isothermality are small, calculations lead to a generalized Korteweg-deVries equation. It is shown from both weakly and highly nonlinear analysis that the presence of the positrons may allow solitary waves to exist. It is found that the effect of the positron density changes the maximum value of the amplitude and M (Mach number) for which solitary waves can exist. The present theory is applicable to analyze arbitrary amplitude ion-acoustic waves associated with positrons which may occur in space plasma.

  11. Nonlinear propagation of ion-acoustic waves in electron-positron-ion plasma with trapped electrons

    SciTech Connect

    Alinejad, H.; Sobhanian, S.; Mahmoodi, J.

    2006-01-15

    A theoretical investigation has been made for ion-acoustic waves in an unmagnetized electron-positron-ion plasma. A more realistic situation in which plasma consists of a negatively charged ion fluid, free positrons, and trapped as well as free electrons is considered. The properties of stationary structures are studied by the reductive perturbation method, which is valid for small but finite amplitude limit, and by pseudopotential approach, which is valid for large amplitude. With an appropriate modified form of the electron number density, two new equations for the ion dynamics have been found. When deviations from isothermality are finite, the modified Korteweg-deVries equation has been found, and for the case that deviations from isothermality are small, calculations lead to a generalized Korteweg-deVries equation. It is shown from both weakly and highly nonlinear analysis that the presence of the positrons may allow solitary waves to exist. It is found that the effect of the positron density changes the maximum value of the amplitude and M (Mach number) for which solitary waves can exist. The present theory is applicable to analyze arbitrary amplitude ion-acoustic waves associated with positrons which may occur in space plasma.

  12. Dynamic optical arbitrary waveform generation with amplitude controlled by interference of two FBG arrays.

    PubMed

    Zhang, Ailing; Li, Changxiu

    2012-10-01

    In this paper, a novel structure of dynamic optical arbitrary waveform generation (O-AWG) with amplitude controlled by interference of two fiber Bragg grating (FBG) arrays is proposed. The FBG array consists of several FBGs and fiber stretchers (FSs). The amplitude is controlled by FSs through interference of two FBG arrays. The phase is controlled by FSs simultaneously. As a result, optical pulse trains with various waveforms as well as pulse trains with nonuniform pulse intensity, pulse spacing and pulse width in each period are obtained via FSs adjustment to change the phase shift of signal in each array. PMID:23188271

  13. Ion Acoustic Solitons and Double Layers in the Solar Wind Having Kappa Distributed Electrons

    NASA Astrophysics Data System (ADS)

    Lakhina, G. S.; Singh, S. V.

    2015-12-01

    It is shown that two types of, slow and fast, ion-acoustic solitary waves can occur in a solar wind plasma consisting of fluid hot protons, hot alpha particles streaming with respect to protons, and suprathermal electrons having k- distribution. The fast ion-acoustic mode is similar to the ion-acoustic mode of proton-electron plasma, and can support only positive potential solitons. The slow ion-acoustic mode is a new mode that occurs due to the presence of alpha particles. This mode can support both positive and negative solitons and double layers. The slow ion-acoustic mode can exist even when the relative streaming, U0, between alphas and protons is zero, provided alpha temperature, Ti, is not exactly equal to 4 times the proton temperature, Tp. An increase of the k- index leads to an increase in the critical Mach number, maximum Mach number and the maximum amplitude of both slow and fast ion-acoustic solitons. The model can explain the amplitudes and widths, but not shapes, of the weak double layers (WDLs) observed in the solar wind at 1 AU by Wind spacecraft in terms of slow ion-acoustic double layers. It is proposed that both slow and fast ion-acoustic solitons may be responsible for the ion- acoustic like wave activity in the solar wind.

  14. The exact equation of motion of a simple pendulum of arbitrary amplitude: a hypergeometric approach

    NASA Astrophysics Data System (ADS)

    Qureshi, M. I.; Rafat, M.; Ismail Azad, S.

    2010-11-01

    The motion of a simple pendulum of arbitrary amplitude is usually treated by approximate methods. By using generalized hypergeometric functions, it is however possible to solve the problem exactly. In this paper, we provide the exact equation of motion of a simple pendulum of arbitrary amplitude. A new and exact expression for the time of swinging of a simple pendulum from the vertical position to an arbitrary angular position θ is given by equation (3.10). The time period of such a pendulum is also exactly expressible in terms of hypergeometric functions. The exact expressions thus obtained are used to plot the graphs that compare the exact time period T(θ0) with the time period T(0) (based on simple harmonic approximation). We also compare the relative difference between T(0) and T(θ0) found from the exact equation of motion with the usual perturbation theory estimate. The treatment is intended for graduate students, who have acquired some familiarity with the hypergeometric functions. This approach may also be profitably used by specialists who encounter during their investigations nonlinear differential equations similar in form to the pendulum equation. Such nonlinear differential equations could arise in diverse fields, such as acoustic vibrations, oscillations in small molecules, turbulence and electronic filters, among others.

  15. Arbitrary amplitude magnetosonic solitary and shock structures in spin quantum plasma

    SciTech Connect

    Sahu, Biswajit; Sinha, Anjana; Roychoudhury, Rajkumar; Khan, Manoranjan

    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.

  16. Compressive and rarefactive ion acoustic solitons in a magnetized two-ion component plasma

    NASA Astrophysics Data System (ADS)

    Ur-Rehman, Hafeez; Mahmood, S.; Aman-ur-Rehman

    2014-10-01

    The formation of compressive (hump) and rarefactive (dip) ion acoustic solitons is studied in magnetized O+- H+- e and O+- H-- e plasmas. The hydrodynamics equations are described for cold heavy (oxygen) ions, warm light (hydrogen) ions and isothermal Boltzmann distributed electrons along with Poisson equations in the presence of a magnetic field. The reductive perturbation method is used to derive the nonlinear Zakharov-Kuznetsov (ZK) equation for an ion acoustic wave in magnetized two-ion component plasma. It is found that two modes of ion acoustic waves with fast and slow speeds can propagate in the linear limit in such a plasma. It is noticed that, in the case of positively charged light hydrogen ions O+- H+- e plasmas, the slow ion acoustic wave solitons formed both potential hump as well as dip structures, while fast ion acoustic wave solitons give only hump structures. However in the case of negatively charged light hydrogen ions O+- H-- e plasmas, the slow ion acoustic wave solitons formed potential hump structures while fast ion acoustic wave solitons produce dip structures. The variations in the amplitude and width of the nonlinear slow and fast ion acoustic wave structures with density, temperature of light ions and magnetic field intensity are obtained in magnetized two-ion component plasmas. The magnetic field has its effect only on the width of the nonlinear ion acoustic wave structures in two-ion component plasmas.

  17. An arbitrary amplitude fast magnetosonic soliton in quantum electron-positron-ion plasmas

    NASA Astrophysics Data System (ADS)

    Hussain, S.; Mushtaq, A.; Mahmood, S.

    2013-02-01

    Nonlinear fast magnetosonic waves are studied in a collisionless homogenous, magnetized electron-positron-ion (e-p-i) plasma. The multi-component quantum magneto-hydrodynamic model is used in which ions are assumed to be dynamic whereas electron and positron quantum fluids are taken to be inertialess. The Sagdeev potential approach is used to obtain arbitrary amplitude magnetosonic structures in dense e-p-i plasmas. It is found that the wave amplitude as well as the width of the magnetosonic structure depends on different plasma parameters such as the electron to positron density ratio, plasma beta, quantum parameter and the Alfvénic Mach number. The numerical results have also been obtained for illustration.

  18. Turbulence in electrostatic ion acoustic shocks

    NASA Technical Reports Server (NTRS)

    Means, R. W.; Coroniti, F. V.; Wong, A. Y.; White, R. B.

    1973-01-01

    Three types of collisionless electrostatic ion acoustic shocks are investigated using a double plasma (DP) device: (1) laminar shocks; (2) small amplitude turbulent shocks in which the turbulence is confined to be upstream of the shock potential jump; and (3) large amplitude turbulent shocks in which the wave turbulence occurs throughout the shock transition. The wave turbulence is generated by ions which are reflected from the shock potential; linear theory spatial growth increments agree with experimental values. The experimental relationship between the shock Mach number and the shock potential is shown to be inconsistent with theoretical shock models which assume that the electrons are isothermal. Theoretical calculations which assume a trapped electron equation of a state and a turbulently flattened velocity distrubution function for the reflected ions yields a Mach number vs potential relationship in agreement with experiment.

  19. Ion acoustic solitons and supersolitons in a magnetized plasma with nonthermal hot electrons and Boltzmann cool electrons

    SciTech Connect

    Rufai, O. R. Bharuthram, R.; Singh, S. V. Lakhina, G. S.

    2014-08-15

    Arbitrary amplitude, ion acoustic solitons, and supersolitons are studied in a magnetized plasma with two distinct groups of electrons at different temperatures. The plasma consists of a cold ion fluid, cool Boltzmann electrons, and nonthermal energetic hot electrons. Using the Sagdeev pseudo-potential technique, the effect of nonthermal hot electrons on soliton structures with other plasma parameters is studied. Our numerical computation shows that negative potential ion-acoustic solitons and double layers can exist both in the subsonic and supersonic Mach number regimes, unlike the case of an unmagnetized plasma where they can only exist in the supersonic Mach number regime. For the first time, it is reported here that in addition to solitions and double layers, the ion-acoustic supersoliton solutions are also obtained for certain range of parameters in a magnetized three-component plasma model. The results show good agreement with Viking satellite observations of the solitary structures with density depletions in the auroral region of the Earth's magnetosphere.

  20. Nonlinear ion acoustic waves scattered by vortexes

    NASA Astrophysics Data System (ADS)

    Ohno, Yuji; Yoshida, Zensho

    2016-09-01

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

  1. Existence domains of slow and fast ion-acoustic solitons in two-ion space plasmas

    SciTech Connect

    Maharaj, S. K.; Bharuthram, R.; Singh, S. V. Lakhina, G. S.

    2015-03-15

    A study of large amplitude ion-acoustic solitons is conducted for a model composed of cool and hot ions and cool and hot electrons. Using the Sagdeev pseudo-potential formalism, the scope of earlier studies is extended to consider why upper Mach number limitations arise for slow and fast ion-acoustic solitons. Treating all plasma constituents as adiabatic fluids, slow ion-acoustic solitons are limited in the order of increasing cool ion concentrations by the number densities of the cool, and then the hot ions becoming complex valued, followed by positive and then negative potential double layer regions. Only positive potentials are found for fast ion-acoustic solitons which are limited only by the hot ion number density having to remain real valued. The effect of neglecting as opposed to including inertial effects of the hot electrons is found to induce only minor quantitative changes in the existence regions of slow and fast ion-acoustic solitons.

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

    SciTech Connect

    Tribeche, Mouloud; Mayout, Saliha; Amour, Rabia

    2009-04-15

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

  3. Nonlinear saturation amplitudes in classical Rayleigh-Taylor instability at arbitrary Atwood numbers

    NASA Astrophysics Data System (ADS)

    Liu, W. H.; Wang, L. F.; Ye, W. H.; He, X. T.

    2012-04-01

    In this research, nonlinear saturation amplitudes (NSAs) of the first two harmonics in Rayleigh-Taylor instability (RTI) for irrotational, incompressible, and inviscid fluids, with a discontinuous profile at arbitrary Atwood numbers, are investigated analytically, by considering nonlinear corrections up to the tenth-order. The NSA of the fundamental mode is defined as the linear (purely exponential) growth amplitude of the fundamental mode at the saturation time when the growth of the fundamental mode (first harmonic) is reduced by 10% in comparison to its corresponding linear growth. The NSA of the second harmonic can be obtained in the same way. The analytic results indicate that the effects of the higher-order correction (HOC) and the Atwood number (A) play an important role in the NSA of the RTI. It is found that the NSA of the fundamental mode decreases with increasing A. And when the HOC effects are considered, the NSA of the fundamental mode is significantly larger than the prediction of previous literatures within the framework of third-order perturbation theory [J. W. Jacobs and I. Catton, J. Fluid Mech. 187, 329 (1988); S. W. Haan, Phys. Fluids B 3, 2349 (1991)]. We find that the NSA of the second harmonic first decreases quickly with increasing A, reaching a minimum, and then increases slowly. Furthermore, the NSAs of the first two harmonics demonstrate the trend of convergence as the order of corrections increases. Thus, it should be included in applications where the NSAs play a role, such as inertial confinement fusion ignition target design.

  4. Stability of steady rotational water-waves of finite amplitude on arbitrary shear currents

    NASA Astrophysics Data System (ADS)

    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.

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

    SciTech Connect

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

    2012-05-15

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

  6. Nonplanar ion-acoustic solitary waves with superthermal electrons in warm plasma

    SciTech Connect

    Eslami, Parvin; Mottaghizadeh, Marzieh; Pakzad, Hamid Reza

    2011-07-15

    In this paper, we consider an unmagnetized plasma consisting of warm adiabatic ions, superthermal electrons, and thermal positrons. Nonlinear cylindrical and spherical modified Korteweg-de Vries (KdV) equations are derived for ion acoustic waves by using reductive perturbation technique. It is observed that an increasing positron concentration decreases the amplitude of the waves. Furthermore, the effects of the superthermal parameter (k) on the ion acoustic waves are found.

  7. Effect of nonthermality of electrons on the speed and shape of ion-acoustic solitary waves in a warm plasma

    SciTech Connect

    Abdelwahed, H. G.; El-Shewy, E. K.

    2012-07-15

    Nonlinear ion-acoustic solitary waves in a warm collisionless plasma with nonthermal electrons are investigated by a direct analysis of the field equations. The Sagdeev's potential is obtained in terms of ion acoustic speed by simply solving an algebraic equation. It is found that the amplitude and width of the ion-acoustic solitons as well as the parametric regime where the solitons can exist are sensitive to the population of energetic non-thermal electrons. The soliton and double layer solutions are obtained as a small amplitude approximation.

  8. Nonplanar ion-acoustic two-soliton systems in quantum electron-positron-ion plasmas

    NASA Astrophysics Data System (ADS)

    Mandal, Pankaj Kumar; Ghorui, Malay Kumar; Saha, Asit; Chatterjee, Prasanta

    2015-01-01

    The basic features of planar and nonplanar time dependent ion-acoustic two-soliton systems have been studied in a three component unmagnetized, collisionless quantum plasma consisting of inertialess electrons and positrons. Using the reductive perturbation technique (RPT), we have derived the Korteweg-de Vries equation for our model. The effects of several parameters on the properties of ion-acoustic two-soliton systems in quantum electron-positron-ion plasmas have been discussed in planar and nonplanar geometries. It has been shown that the properties of ion-acoustic two-soliton systems are affected significantly due to cylindrical and spherical geometries. The amplitude of the cylindrical two-soliton system is smaller than that of the spherical two-soliton system for small values of | τ|. The propagation of ion-acoustic two-soliton systems is quite different from the propagation of ion-acoustic two-soliton systems in a nonplanar geometry. The present investigation may have relevance in the study of the propagation of ion-acoustic two-soliton systems in space and laboratory plasmas.

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

    SciTech Connect

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

    2010-10-15

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

  10. Quantum ion acoustic solitary waves in electron ion plasmas: A Sagdeev potential approach

    NASA Astrophysics Data System (ADS)

    Mahmood, S.; Mushtaq, A.

    2008-05-01

    Linear and nonlinear ion acoustic waves are studied in unmagnetized electron-ion quantum plasmas. Sagdeev potential approach is employed to describe the nonlinear quantum ion acoustic waves. It is found that density dips structures are formed in the subsonic region in a electron-ion quantum plasma case. The amplitude of the nonlinear structures remains constant and the width is broadened with the increase in the quantization of the system. However, the nonlinear wave amplitude is reduced with the increase in the wave Mach number. The numerical results are also presented.

  11. Ion acoustic shock waves in weakly relativistic multicomponent quantum plasma

    NASA Astrophysics Data System (ADS)

    Gill, T. S.; Bains, A. S.; Bedi, C.

    2010-02-01

    Ion acoustic Shock waves (IASWs) are studied in an collisionless unmagnetized relativistic quantum electron-positron-ion(e-p-i) plasma employing the quantum hydro -dynamic(QHD) model. Korteweg-deVries- Burger equation(KdVB) is derived using small amplitude perturbation expansion method to study the nonlinear propagation of the quantum IASWs. It is found that the coefficients of the KdVB equation are significantely modified by the positron density p, relativistic factor(Ur), temperatures σ, kinematic viscosity η and quantum factor(H).

  12. Dust ion acoustic soliton in pair-ion plasmas with non-isothermal electrons

    NASA Astrophysics Data System (ADS)

    Mushtaq, A.; Nasir Khattak, M.; Ahmad, Zulfiqar; Qamar, A.

    2012-04-01

    Dust ion acoustic (DIA) solitons in an unmagnetized pair-ion (PI) plasmas with adiabatic pair-ions, non-isothermal electrons, and negatively charged background dust are investigated, using both small and arbitrary amplitude techniques. An energy integral equation involving the Sagdeev potential is derived, and basic properties of the large amplitude solitary structures are investigated. The effects of dust concentration, resonant electrons, and ion temperatures on the profiles of the Sagdeev potential and corresponding solitary waves are studied. The related Schamel-Korteweg-de Vries (S-KdV) equation with mixed-nonlinearity is derived by expanding the Sagdeev potential. Asymptotic solutions for different orders of nonlinearity are discussed for DIA solitary waves. The present work is applicable to understand the wave phenomena and associated nonlinear electrostatic perturbations in the doped pair ion plasmas, not completely filtered e.g., pair ion-electron plasmas, enriched with an extra massive charged component (e.g., dust defects), which may be academic for the moment but might be of interest for forthcoming experiments in laboratory (space) plasmas.

  13. Characteristics of ion acoustic solitary waves in a negative ion plasma with superthermal electrons

    SciTech Connect

    Rouhani, M. R.; Ebne Abbasi, Z.

    2012-11-15

    The behavior of ion acoustic solitons in a plasma including positive and negative ions and kappa distributed electrons is studied, using both small amplitude and arbitrary amplitude approaches. The existence regions of compressive and rarefactive solitons will depend on negative to positive ion density ratio ({nu}) and kappa parameter as well as positive to negative ion mass ratio (Q). The numerical analysis of Sagdeev potential shows that for a chosen plasma with fixed Q, the existence regime of compressive solitons is decreased (increased) by increasing density ratio (kappa parameter), while for rarefactive solitons these conditions are quite opposite. Additionally, the possibility of propagation of both compressive and rarefactive subsonic solitons is investigated. It is found that by increasing negative ions, the existence domains of subsonic solitons are decreased, so that in excess of negative ions subsonic solitons will not propagate even at the presence of superthermal electrons. Indeed, there is a critical negative ion density ratio for all values of kappa, above that only supersonic solitons are observed. Furthermore, in addition to the previous results based on Cairns-distributed electrons [R. A. Cairns et al., Geophys. Res. Lett. 22, 2709 (1995)], which predicted that both compressive and rarefactive solitons can coexist simultaneously, we have also found the regions of {nu} and {kappa} in which either positive or negative potentials are permitted (i.e., not together). This research will be helpful in understanding the properties of space and laboratory plasmas containing negative ions with energetic electrons.

  14. Cylindrical ion-acoustic solitary waves in electronegative plasmas with superthermal electrons

    SciTech Connect

    Eslami, Parvin; Mottaghizadeh, Marzieh

    2012-06-15

    By using the standard reductive perturbation technique, a three-dimensional cylindrical Kadomtsev-Petviashvili equation (CKPE), which governs the dynamics of ion acoustic solitary waves (IASWs), is derived for small but finite amplitude ion-acoustic waves in cylindrical geometry in a collisionless unmagnetized plasma with kappa distributed electrons, thermal positrons, and cold ions. The generalized expansion method is used to solve analytically the CKPE. The existence regions of localized pulses are investigated. It is found that the solution of the CKPE supports only compressive solitary waves. Furthermore, the effects of superthermal electrons, the ratio of the electron temperature to positron temperature, the ratio of the positron density to electron density and direction cosine of the wave propagation on the profiles of the amplitudes, and widths of the solitary structures are examined numerically. It is shown these parameters play a vital role in the formation of ion acoustic solitary waves.

  15. Ion heating via turbulent ion acoustic waves.

    NASA Technical Reports Server (NTRS)

    Taylor, R. J.; Coroniti, F. V.

    1972-01-01

    The ion acoustic turbulence in the turbulent-heating experiment reported is excited by the ion-ion beam instability. Graphs are presented, showing the spatial evolution of the parallel ion beam energy and the spatial evolution of the ion acoustic turbulent wave spectrum. The observed characteristics of test waves in a turbulent beam-plasma imply that wave saturation is a dynamic balance between the emission of waves by the beam and the destruction or damping of wave coherence by the turbulent diffusion of particle orbits.

  16. Quantum corrections to nonlinear ion acoustic wave with Landau damping

    SciTech Connect

    Mukherjee, Abhik; Janaki, M. S.; Bose, Anirban

    2014-07-15

    Quantum corrections to nonlinear ion acoustic wave with Landau damping have been computed using Wigner equation approach. The dynamical equation governing the time development of nonlinear ion acoustic wave with semiclassical quantum corrections is shown to have the form of higher KdV equation which has higher order nonlinear terms coming from quantum corrections, with the usual classical and quantum corrected Landau damping integral terms. The conservation of total number of ions is shown from the evolution equation. The decay rate of KdV solitary wave amplitude due to the presence of Landau damping terms has been calculated assuming the Landau damping parameter α{sub 1}=√(m{sub e}/m{sub i}) to be of the same order of the quantum parameter Q=ℏ{sup 2}/(24m{sup 2}c{sub s}{sup 2}L{sup 2}). The amplitude is shown to decay very slowly with time as determined by the quantum factor Q.

  17. Polarization-sensitive optical coherence tomography using continuous polarization modulation with arbitrary phase modulation amplitude

    NASA Astrophysics Data System (ADS)

    Lu, Zenghai; Kasaragod, Deepa K.; Matcher, Stephen J.

    2012-03-01

    We demonstrate theoretically and experimentally that the phase retardance and relative optic-axis orientation of a sample can be calculated without prior knowledge of the actual value of the phase modulation amplitude when using a polarization-sensitive optical coherence tomography system based on continuous polarization modulation (CPM-PS-OCT). We also demonstrate that the sample Jones matrix can be calculated at any values of the phase modulation amplitude in a reasonable range depending on the system effective signal-to-noise ratio. This has fundamental importance for the development of clinical systems by simplifying the polarization modulator drive instrumentation and eliminating its calibration procedure. This was validated on measurements of a three-quarter waveplate and an equine tendon sample by a fiber-based swept-source CPM-PS-OCT system.

  18. Dust ion acoustic solitary waves in a collisional dusty plasma with dust grains having Gaussian distribution

    SciTech Connect

    Maitra, Sarit; Banerjee, Gadadhar

    2014-11-15

    The influence of dust size distribution on the dust ion acoustic solitary waves in a collisional dusty plasma is investigated. It is found that dust size distribution changes the amplitude and width of a solitary wave. A critical wave number is derived for the existence of purely damping mode. A deformed Korteweg-de Vries (dKdV) equation is obtained for the propagation of weakly nonlinear dust ion acoustic solitary waves and the effect of different plasma parameters on the solution of this equation is also presented.

  19. Quantum ion-acoustic double layers in unmagnetized dense electron-positron-ion plasmas

    NASA Astrophysics Data System (ADS)

    Khan, S. A.; Mahmood, S.; Ali, S.

    2009-04-01

    The existence of small amplitude quantum ion-acoustic double layers is studied in an unmagnetized dense electron-positron-ion plasma. For this purpose, the quantum hydrodynamic model is employed to derive a deformed Korteweg-de Vries (dKdV) equation. The steady state double layer solution of dKdV equation is obtained and its dependence on various parameters is discussed. It is found that only compressive double layers can exist in such plasmas. The analytical and numerical studies reveal that the quantum ion-acoustic double layer structures strongly depend on quantum diffraction effects and positron number density.

  20. Linear and nonlinear ion-acoustic waves in very dense magnetized plasmas

    SciTech Connect

    Khan, S. A.; Mahmood, S.; Saleem, H.

    2008-08-15

    Obliquely propagating linear and weakly nonlinear ion-acoustic waves in a magnetized quantum plasma are investigated by employing the quantum hydrodynamic formulation. A linear dispersion relation is presented and the nonlinear Korteweg-de Vries equation is derived using the reductive perturbative method. The dispersion caused by the quantum diffraction effects is possible only in a very short wavelength regime. The amplitude and width of the solitons formed by the ion-acoustic waves propagating in a magnetized plasma depend upon various parameters. Possible applications of the results to dense plasmas are discussed.

  1. Linear and nonlinear quantum ion-acoustic waves in dense magnetized electron-positron-ion plasmas

    SciTech Connect

    Khan, S. A.; Masood, W.

    2008-06-15

    The linear and nonlinear quantum ion-acoustic waves propagating obliquely in two dimensions in superdense, magnetized electron-positron-ion quantum plasma are investigated on the basis of quantum hydrodynamic model. It is found in linear analysis that the quantum corrections of diffraction are important in the very short wavelength regime that may be found in dense astrophysical plasmas. To investigate the solitary waves, the Zakharov-Kuznetsov equation is derived and the solution is presented in the small amplitude limit. By numerical analysis, it is found that the soliton structure of the ion acoustic wave depends upon quantum pressure, concentration of positrons, strength of magnetic field, and the propagation angle.

  2. Linear and nonlinear quantum ion-acoustic waves in dense magnetized electron-positron-ion plasmas

    NASA Astrophysics Data System (ADS)

    Khan, S. A.; Masood, W.

    2008-06-01

    The linear and nonlinear quantum ion-acoustic waves propagating obliquely in two dimensions in superdense, magnetized electron-positron-ion quantum plasma are investigated on the basis of quantum hydrodynamic model. It is found in linear analysis that the quantum corrections of diffraction are important in the very short wavelength regime that may be found in dense astrophysical plasmas. To investigate the solitary waves, the Zakharov-Kuznetsov equation is derived and the solution is presented in the small amplitude limit. By numerical analysis, it is found that the soliton structure of the ion acoustic wave depends upon quantum pressure, concentration of positrons, strength of magnetic field, and the propagation angle.

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

    PubMed

    El-Shamy, E F

    2015-03-01

    The complex pattern and propagation characteristics of nonlinear periodic ion-acoustic waves, namely, ion-acoustic cnoidal waves, in a dense relativistic degenerate magnetoplasma consisting of relativistic degenerate electrons and nondegenerate cold ions are investigated. By means of the reductive perturbation method and appropriate boundary conditions for nonlinear periodic waves, a nonlinear modified Korteweg-de Vries (KdV) equation is derived and its cnoidal wave is analyzed. The various solutions of nonlinear ion-acoustic cnoidal and solitary waves are presented numerically with the Sagdeev potential approach. The analytical solution and numerical simulation of nonlinear ion-acoustic cnoidal waves of the nonlinear modified KdV equation are studied. Clearly, it is found that the features (amplitude and width) of nonlinear ion-acoustic cnoidal waves are proportional to plasma number density, ion cyclotron frequency, and direction cosines. The numerical results are applied to high density astrophysical situations, such as in superdense white dwarfs. This research will be helpful in understanding the properties of compact astrophysical objects containing cold ions with relativistic degenerate electrons. PMID:25871222

  4. Ion Acoustic Waves in Ultracold Neutral Plasmas

    SciTech Connect

    Castro, J.; McQuillen, P.; Killian, T. C.

    2010-08-06

    We photoionize laser-cooled atoms with a laser beam possessing spatially periodic intensity modulations to create ultracold neutral plasmas with controlled density perturbations. Laser-induced fluorescence imaging reveals that the density perturbations oscillate in space and time, and the dispersion relation of the oscillations matches that of ion acoustic waves, which are long-wavelength, electrostatic, density waves.

  5. Ion acoustic solitary waves and double layers in a plasma with two temperature electrons featuring Tsallis distribution

    SciTech Connect

    Shalini, Saini, N. S.

    2014-10-15

    The propagation properties of large amplitude ion acoustic solitary waves (IASWs) are studied in a plasma containing cold fluid ions and multi-temperature electrons (cool and hot electrons) with nonextensive distribution. Employing Sagdeev pseudopotential method, an energy balance equation has been derived and from the expression for Sagdeev potential function, ion acoustic solitary waves and double layers are investigated numerically. The Mach number (lower and upper limits) for the existence of solitary structures is determined. Positive as well as negative polarity solitary structures are observed. Further, conditions for the existence of ion acoustic double layers (IADLs) are also determined numerically in the form of the critical values of q{sub c}, f and the Mach number (M). It is observed that the nonextensivity of electrons (via q{sub c,h}), concentration of electrons (via f) and temperature ratio of cold to hot electrons (via β) significantly influence the characteristics of ion acoustic solitary waves as well as double layers.

  6. Information transmission over an amplitude damping channel with an arbitrary degree of memory

    NASA Astrophysics Data System (ADS)

    D'Arrigo, Antonio; Benenti, Giuliano; Falci, Giuseppe; Macchiavello, Chiara

    2015-12-01

    We study the performance of a partially correlated amplitude damping channel acting on two qubits. We derive lower bounds for the single-shot classical capacity by studying two kinds of quantum ensembles, one which allows us to maximize the Holevo quantity for the memoryless channel and the other allowing the same task but for the full-memory channel. In these two cases we also show the amount of entanglement which is involved in achieving the maximum of the Holevo quantity. For the single-shot quantum capacity we discuss both a lower and an upper bound, achieving a good estimate for high values of the channel transmissivity. We finally compute the entanglement-assisted classical channel capacity.

  7. Arbitrary amplitude kinetic Alfven solitary waves in two temperature electron superthermal plasma

    NASA Astrophysics Data System (ADS)

    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.

  8. Arbitrary amplitude slow electron-acoustic solitons in three-electron temperature space plasmas

    SciTech Connect

    Mbuli, L. N.; Maharaj, S. K.; Bharuthram, R.; Singh, S. V.; Lakhina, G. S.

    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.

  9. Ion acoustic solitary waves in magneto-rotating plasmas

    NASA Astrophysics Data System (ADS)

    Mushtaq, A.

    2010-08-01

    Propagation of an ion acoustic wave (IAW) in a magnetized electron-ion plasma, which is rotating around an axis at an angle θ with the direction of magnetic field, is studied by incorporating the effects of trapped and untrapped electron distributions. Employing the perturbation scheme, Korteweg-deVries and Schamel's modified KdV equations are derived for the small angle θ which may support the nonlinear IAW on a slow time scale of ion motion. The amplitude and width of the solitary wave in both cases (trapped and untrapped electrons) have been discussed with the effects of oblique rotation and external magnetic field. It is shown that the nonlinear effects considerably influence the propagation of waves in rotating plasmas.

  10. Ion acoustic shock waves in electron-positron-ion quantum plasma

    NASA Astrophysics Data System (ADS)

    Masood, W.; Mirza, Arshad M.; Hanif, M.

    2008-07-01

    Ion acoustic shock waves (IASWs) are studied in an unmagnetized quantum plasma consisting of electrons, positrons, and ions employing the quantum hydrodynamic (QHD) model. Nonlinear quantum IASWs are investigated by deriving the Korteweg-deVries-Burger equation under the small amplitude perturbation expansion method. The dissipation is introduced by taking into account the kinematic viscosity among the plasma constituents. It is found that the strength of the ion acoustic shock wave is maximum for spherical, intermediate for cylindrical, and minimum for planar geometry. The temporal evolution of the shock for a quantum e-p-i plasma in a spherical geometry is also investigated. It is found that the strength and the steepness of the quantum ion acoustic shock wave increases with decreasing stretched time coordinate (representing slow time scale) |τ|. It is also found that an increase in the quantum Bohm potential decreases the strength as well as the steepness of the shock. The temporal evolution of the quantum ion acoustic solitons in an e-p-i plasma for cylindrical and spherical geometries is also explored by substituting the dissipative coefficient C equal to zero. The relevance of the present study with regard to the dense astrophysical environments is also pointed out.

  11. Ion acoustic shock waves in electron-positron-ion quantum plasma

    SciTech Connect

    Masood, W.; Mirza, Arshad M.; Hanif, M.

    2008-07-15

    Ion acoustic shock waves (IASWs) are studied in an unmagnetized quantum plasma consisting of electrons, positrons, and ions employing the quantum hydrodynamic (QHD) model. Nonlinear quantum IASWs are investigated by deriving the Korteweg-deVries-Burger equation under the small amplitude perturbation expansion method. The dissipation is introduced by taking into account the kinematic viscosity among the plasma constituents. It is found that the strength of the ion acoustic shock wave is maximum for spherical, intermediate for cylindrical, and minimum for planar geometry. The temporal evolution of the shock for a quantum e-p-i plasma in a spherical geometry is also investigated. It is found that the strength and the steepness of the quantum ion acoustic shock wave increases with decreasing stretched time coordinate (representing slow time scale) |{tau}|. It is also found that an increase in the quantum Bohm potential decreases the strength as well as the steepness of the shock. The temporal evolution of the quantum ion acoustic solitons in an e-p-i plasma for cylindrical and spherical geometries is also explored by substituting the dissipative coefficient C equal to zero. The relevance of the present study with regard to the dense astrophysical environments is also pointed out.

  12. Generation of ion-acoustic waves in an inductively coupled, low-pressure discharge lamp

    SciTech Connect

    Camparo, J. C.; Klimcak, C. M.

    2006-04-15

    For a number of years it has been known that the alkali rf-discharge lamps used in atomic clocks can exhibit large amplitude intensity oscillations. These oscillations arise from ion-acoustic plasma waves and have typically been associated with erratic clock behavior. Though large amplitude ion-acoustic plasma waves are clearly deleterious for atomic clock operation, it does not follow that small amplitude oscillations have no utility. Here, we demonstrate two easily implemented methods for generating small amplitude ion-acoustic plasma waves in alkali rf-discharge lamps. Furthermore, we demonstrate that the frequency of these waves is proportional to the square root of the rf power driving the lamp and therefore that their examination can provide an easily accessible parameter for monitoring and controlling the lamp's plasma conditions. This has important consequences for precise timekeeping, since the atomic ground-state hyperfine transition, which is the heart of the atomic clock signal, can be significantly perturbed by changes in the lamp's output via the ac-Stark shift.

  13. Effects of trapped electrons on the oblique propagation of ion acoustic solitary waves in electron-positron-ion plasmas

    NASA Astrophysics Data System (ADS)

    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.

  14. Nonlinear ion-acoustic structures in a nonextensive electron–positron–ion–dust plasma: Modulational instability and rogue waves

    SciTech Connect

    Guo, Shimin; Mei, Liquan; Sun, Anbang

    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.

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

    SciTech Connect

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

    2014-09-15

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

  16. Ion acoustic solitons in a relativistic warm plasma with density gradient

    SciTech Connect

    Malik, H.K.

    1995-10-01

    Modified Korteweg-deVries equation (mK-dV), which governs the behavior of ion acoustic solitons in a relativistic warm plasma with density gradient, is derived. The electron inertia is also taken into account which is important when the streaming ions are present in the plasma. A solution of the mK-dV equation is obtained for the constant density gradient. When the ion acoustic soliton propagates into the lower plasma density region, its amplitude and energy increase, but the width decreases; the same is the case for the stronger density gradients. Plasmas with high-energy streaming ions are found, for example, in the plasma sheet boundary layer of the earth`s magnetosphere and in the Van Allen radiation belts.

  17. Planar and non-planar ion acoustic shock waves in electron positron ion plasmas

    NASA Astrophysics Data System (ADS)

    Masood, Waqas; Jehan, Nusrat; Mirza, Arshad M.; Sakanaka, P. H.

    2008-06-01

    Ion acoustic shock waves (IASW's) are studied in an unmagnetized plasma consisting of electrons, positrons and adiabatically hot positive ions. This is done by deriving the Kortweg-deVries-Burger (KdVB) equation under the small amplitude perturbation expansion method. The dissipation is introduced by taking into account the kinematic viscosity among the plasma constituents. It is found that the strength of ion acoustic shock wave is maximum for spherical, intermediate for cylindrical, and minimum for planar geometry. It is observed that the positron concentration, ratio of ion to electron temperature, and the plasma kinematic viscosity significantly modifies the shock structure. Finally, it is found that the temporal evolution of the non-planar IASW's is quite different by comparison with the planar geometry. The relevance of the present study with regard to the dense astrophysical environments is also pointed out.

  18. Excitation of nonlinear ion acoustic waves in CH plasmas

    NASA Astrophysics Data System (ADS)

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

    2016-08-01

    Excitation of nonlinear ion acoustic wave (IAW) by an external electric field is demonstrated by Vlasov simulation. The frequency calculated by the dispersion relation with no damping is verified much closer to the resonance frequency of the small-amplitude nonlinear IAW than that calculated by the linear dispersion relation. When the wave number k λ D e increases, the linear Landau damping of the fast mode (its phase velocity is greater than any ion's thermal velocity) increases obviously in the region of T i / T e < 0.2 in which the fast mode is weakly damped mode. As a result, the deviation between the frequency calculated by the linear dispersion relation and that by the dispersion relation with no damping becomes larger with k λ D e increasing. When k λ D e is not large, such as k λ D e = 0.1 , 0.3 , 0.5 , the nonlinear IAW can be excited by the driver with the linear frequency of the modes. However, when k λ D e is large, such as k λ D e = 0.7 , the linear frequency cannot be applied to exciting the nonlinear IAW, while the frequency calculated by the dispersion relation with no damping can be applied to exciting the nonlinear IAW.

  19. Ion-acoustic dressed solitons in a dusty plasma

    SciTech Connect

    Tiwari, R.S.; Mishra, M.K.

    2006-06-15

    Using the reductive perturbation method, equations for ion-acoustic waves governing the evolution of first- and second-order potentials in a dusty plasma including the dynamics of charged dust grains have been derived. The renormalization procedure of Kodama and Taniuti is used to obtain a steady state nonsecular solution of these equations. The variation of velocity and width of the Korteweg-de Vries (KdV) as well as dressed solitons with amplitude have been studied for different concentrations and charge multiplicity of dust grains. The higher-order perturbation corrections to the KdV soliton description significantly affect the characteristics of the solitons in dusty plasma. It is found that in the presence of positively charged dust grains the system supports only compressive solitons. However, the plasma with negatively charged dust grains can support compressive solitons only up to a certain concentration of dust. Above this critical concentration of negative charge, the dusty plasma can support rarefactive solitons. An expression for the critical concentration of negatively charged dust in terms of charge and mass ratio of dust grains with plasma ions is also derived.

  20. Ion Acoustic Modes in Warm Dense Matter

    NASA Astrophysics Data System (ADS)

    Hartley, Nicholas; Monaco, Guilio; White, Thomas; Gregori, Gianluca; Graham, Peter; Fletcher, Luke; Appel, Karen; Tschentscher, Thomas; Lee, Hae Ja; Nagler, Bob; Galtier, Eric; Granados, Eduardo; Heimann, Philip; Zastrau, Ulf; Doeppner, Tilo; Gericke, Dirk; Lepape, Sebastien; Ma, Tammy; Pak, Art; Schropp, Andreas; Glenzer, Siegfried; Hastings, Jerry

    2015-06-01

    We present results that, for the first time, show scattering from ion acoustic modes in warm dense matter, representing an unprecedented level of energy resolution in the study of dense plasmas. The experiment was carried out at the LCLS facility in California on an aluminum sample at 7 g/cc and 5 eV. Using an X-ray probe at 8 keV, shifted peaks at +/-150 meV were observed. Although the energy shifts from interactions with the acoustic waves agree with predicted values from DFT-MD models, a central (elastic) peak was also observed, which did not appear in modelled spectra and may be due to the finite timescale of the simulation. Data fitting with a hydrodynamic form has proved able to match the observed spectrum, and provide measurements of some thermodynamic properties of the system, which mostly agree with predicted values. Suggest for further experiments to determine the cause of the disparity are also given.

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

    SciTech Connect

    Jain, S. L.; Tiwari, R. S.; Mishra, M. K.

    2012-10-15

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

  2. Ion-acoustic super rogue waves in ultracold neutral plasmas with nonthermal electrons

    SciTech Connect

    El-Tantawy, S. A.; El-Bedwehy, N. A.; El-Labany, S. K.

    2013-07-15

    The ion-acoustic rogue waves in ultracold neutral plasmas consisting of ion fluid and nonthermal electrons are reported. A reductive perturbation method is used to obtain a nonlinear Schrödinger equation for describing the system and the modulation instability of the ion-acoustic wave is analyzed. The critical wave number k{sub c}, which indicates where the modulational instability sets in, has been determined. Moreover, the possible region for the ion-acoustic rogue waves to exist is defined precisely. The effects of the nonthermal parameter β and the ions effective temperature ratio σ{sub *} on the critical wave number k{sub c} are studied. It is found that there are two critical wave numbers in our plasma system. For low wave number, increasing β would lead to cringe k{sub c} until β approaches to its critical value β{sub c}, then further increase of β beyond β{sub c} would enhance the values of k{sub c}. For large wave numbers, the increase of β would lead to a decrease of k{sub c}. However, increasing σ{sub *} would lead to the reduction of k{sub c} for all values of the wave number. The dependence of the rogue waves profile on the plasma parameters is numerically examined. It is found that the rogue wave amplitudes have complex behavior with increasing β. Furthermore, the enhancement of σ{sub *} and the carrier wave number k reduces the rogue wave amplitude. It is noticed that near to the critical wave number, the rogue wave amplitude becomes high, but it shrinks whenever we stepped away from k{sub c}. The implications of our results in laboratory ultracold neutral plasma experiments are briefly discussed.

  3. PIC simulation of compressive and rarefactive dust ion-acoustic solitary waves

    NASA Astrophysics Data System (ADS)

    Li, Zhong-Zheng; Zhang, Heng; Hong, Xue-Ren; Gao, Dong-Ning; Zhang, Jie; Duan, Wen-Shan; Yang, Lei

    2016-08-01

    The nonlinear propagations of dust ion-acoustic solitary waves in a collisionless four-component unmagnetized dusty plasma system containing nonextensive electrons, inertial negative ions, Maxwellian positive ions, and negatively charged static dust grains have been investigated by the particle-in-cell method. By comparing the simulation results with those obtained from the traditional reductive perturbation method, it is observed that the rarefactive KdV solitons propagate stably at a low amplitude, and when the amplitude is increased, the prime wave form evolves and then gradually breaks into several small amplitude solitary waves near the tail of soliton structure. The compressive KdV solitons propagate unstably and oscillation arises near the tail of soliton structure. The finite amplitude rarefactive and compressive Gardner solitons seem to propagate stably.

  4. Higher order solutions to ion-acoustic solitons in a weakly relativistic two-fluid plasma

    SciTech Connect

    Gill, Tarsem Singh; Bala, Parveen; Kaur, Harvinder

    2008-12-15

    The nonlinear wave structure of small amplitude ion-acoustic solitary waves (IASs) is investigated in a two-fluid plasma consisting of weakly relativistic streaming ions and electrons. Using the reductive perturbation theory, the basic set of governing equations is reduced to the Korteweg-de Vries (KdV) equation for the lowest order perturbation. This analysis is further extended using the renormalization technique for the inclusion of higher order nonlinear and dispersive effects for better accuracy. The effect of higher order correction and various parameters on the soliton characteristics is investigated and also discussed.

  5. Reflection of ion acoustic solitons in a plasma having negative ions

    SciTech Connect

    Chauhan, S.S.; Malik, H.K.; Dahiya, R.P.

    1996-11-01

    Reflection of compressive and rarefactive ion acoustic solitons propagating in an inhomogeneous plasma in the presence of negative ions is investigated. Modified Korteweg{endash}deVries equations for incident and reflected solitons are derived and solved. The amplitude of incident and reflected solitons increases with negative to positive ion density ratio. With increasing density ratio, reflection of rarefactive solitons is reinforced whereas that of compressive solitons weakened. The rarefactive solitons are found to undergo stronger reflection than the compressive ones. {copyright} {ital 1996 American Institute of Physics.}

  6. Investigation of nonextensivity trapped electrons effect on the solitary ion-acoustic wave using fractional Schamel equation

    NASA Astrophysics Data System (ADS)

    Nazari-Golshan, A.

    2016-08-01

    Ion-acoustic (IA) solitary wave propagation is investigated by solving the fractional Schamel equation (FSE) in a homogenous system of unmagnetized plasma. This plasma consists of the nonextensive trapped electrons and cold fluid ions. The effects of the nonextensive q-parameter, electron trapping, and fractional parameter have been studied. The FSE is derived by using the semi-inverse and Agrawal's methods. The analytical results show that an increase in the amount of electron trapping and nonextensive q-parameter increases the soliton ion-acoustic amplitude in agreement with the previously obtained results. However, it is vice-versa for the fractional parameter. This feature leads to the fact that the fractional parameter may be used to increase the IA soliton amplitude instead of increasing electron trapping and nonextensive parameters.

  7. Ion-acoustic solitary waves in a dense pair-ion plasma containing degenerate electrons and positrons

    NASA Astrophysics Data System (ADS)

    Abdelsalam, U. M.; Moslem, W. M.; Shukla, P. K.

    2008-05-01

    Fully nonlinear propagation of ion-acoustic solitary waves in a collisionless dense/quantum electron-positron-ion plasma is investigated. The electrons and positrons are assumed to follow the Thomas-Fermi density distribution and the ions are described by the hydrodynamic equations. An energy balance-like equation involving a Sagdeev-type pseudo-potential is derived. Finite amplitude solutions are obtained numerically and their characteristics are discussed. The small-but finite-amplitude limit is also considered and an exact analytical solution is obtained. The present studies might be helpful to understand the excitation of nonlinear ion-acoustic solitary waves in a degenerate plasma such as in superdense white dwarfs.

  8. Kinetic study of ion-acoustic plasma vortices

    SciTech Connect

    Khan, S. A.; Aman-ur-Rehman; Mendonca, J. T.

    2014-09-15

    The kinetic theory of electron plasma waves with finite orbital angular momentum has recently been introduced by Mendonca. This model shows possibility of new kind of plasma waves and instabilities. We have extended the theory to ion-acoustic plasma vortices carrying orbital angular momentum. The dispersion equation is derived under paraxial approximation which exhibits a kind of linear vortices and their Landau damping. The numerical solutions are obtained and compared with analytical results which are in good agreement. The physical interpretation of the ion-acoustic plasma vortices and their Landau resonance conditions are given for typical case of Maxwellian plasmas.

  9. Ion acoustic shocks in magneto rotating Lorentzian plasmas

    SciTech Connect

    Hussain, S.; Akhtar, N.; Hasnain, H.

    2014-12-15

    Ion acoustic shock structures in magnetized homogeneous dissipative Lorentzian plasma under the effects of Coriolis force are investigated. The dissipation in the plasma system is introduced via dynamic viscosity of inertial ions. The electrons are following the kappa distribution function. Korteweg-de Vries Burger (KdVB) equation is derived by using reductive perturbation technique. It is shown that spectral index, magnetic field, kinematic viscosity of ions, rotational frequency, and effective frequency have significant impact on the propagation characteristic of ion acoustic shocks in such plasma system. The numerical solution of KdVB equation is also discussed and transition from oscillatory profile to monotonic shock for different plasma parameters is investigated.

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

    SciTech Connect

    Kaladze, T.; Mahmood, S.

    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.

  11. Multichannel 0→2 and 1→2 transition amplitudes for arbitrary spin particles in a finite volume

    DOE PAGES

    Hansen, Maxwell; Briceno, Raul

    2015-10-01

    We present a model-independent, non-perturbative relation between finite-volume matrix elements and infinite-volumemore » $$\\textbf{0}\\rightarrow\\textbf{2}$$ and $$\\textbf{1}\\rightarrow\\textbf{2}$$ transition amplitudes. Our result accommodates theories in which the final two-particle state is coupled to any number of other two-body channels, with all angular momentum states included. The derivation uses generic, fully relativistic field theory, and is exact up to exponentially suppressed corrections in the lightest particle mass times the box size. This work distinguishes itself from previous studies by accommodating particles with any intrinsic spin. To illustrate the utility of our general result, we discuss how it can be implemented for studies of $$N+\\mathcal{J}~\\rightarrow~(N\\pi,N\\eta,N\\eta',\\Sigma K,\\Lambda K)$$ transitions, where $$\\mathcal{J}$$ is a generic external current. The reduction of rotational symmetry, due to the cubic finite volume, manifests in this example through the mixing of S- and P-waves when the system has nonzero total momentum.« less

  12. Quantum ion-acoustic wave oscillations in metallic nanowires

    SciTech Connect

    Moradi, Afshin

    2015-05-15

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

  13. Ion acoustic solitons in Earth's upward current region

    SciTech Connect

    Main, D. S.; Scholz, C.; Newman, D. L.; Ergun, R. E.

    2012-07-15

    The formation and evolution of ion acoustic solitons in Earth's auroral upward current region are studied using one- and two-dimensional (2D) electrostatic particle-in-cell simulations. The one-dimensional simulations are confined to processes that occur in the auroral cavity and include four plasma populations: hot electrons, H{sup +} and O{sup +} anti-earthward ion beams, and a hot H{sup +} background population. Ion acoustic solitons are found to form for auroral-cavity ion beams consistent with acceleration through double-layer (DL) potentials measured by FAST. A simplified one-dimensional model simulation is then presented in order to isolate the mechanisms that lead to the formation of the ion acoustic soliton. Results of a two-dimensional simulation, which include both the ionosphere and the auroral cavity, separated by a low-altitude DL, are then presented in order to confirm that the soliton forms in a more realistic 2D geometry. The 2D simulation is initialized with a U-shaped potential structure that mimics the inferred shape of the low altitude transition region based on observations. In this simulation, a soliton localized perpendicular to the geomagnetic field is observed to form and reside next to the DL. Finally, the 2D simulation results are compared with FAST data and it is found that certain aspects of the data can be explained by assuming the presence of an ion acoustic soliton.

  14. Linear and nonlinear coupled drift and ion acoustic waves in collisional pair ion-electron magnetoplasma

    SciTech Connect

    Mushtaq, A.; Saeed, R.; Haque, Q.

    2011-04-15

    Linear and nonlinear coupled electrostatic drift and ion acoustic waves are studied in inhomogeneous, collisional pair ion-electron plasma. The Korteweg-de Vries-Burgers (KdVB) equation for a medium where both dispersion and dissipation are present is derived. An attempt is made to obtain exact solution of KdVB equation by using modified tanh-coth method for arbitrary velocity of nonlinear drift wave. Another exact solution for KdVB is obtained, which gives a structure of shock wave. Korteweg-de Vries (KdV) and Burgers equations are derived in limiting cases with solitary and monotonic shock solutions, respectively. Effects of species density, magnetic field, obliqueness, and the acoustic to drift velocity ratio on the solitary and shock solutions are investigated. The results discussed are useful in understanding of low frequency electrostatic waves at laboratory pair ion plasmas.

  15. Compressive and rarefactive dust-ion-acoustic Gardner solitons in a multi-component dusty plasma

    SciTech Connect

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

    2015-04-15

    The linear and nonlinear propagations of dust-ion-acoustic solitary waves (DIASWs) in a collisionless four-component unmagnetized dusty plasma system containing nonextensive electrons, inertial negative ions, Maxwellian positive ions, and negatively charged static dust grains have been investigated theoretically. The linear properties are analyzed by using the normal mode analysis and the reductive perturbation method is used to derive the nonlinear equations, namely, the Korteweg-de Vries (K-dV), the modified K-dV (mK-dV), and the Gardner equations. The basic features (viz., polarity, amplitude, width, etc.) of Gardner solitons (GS) are found to exist beyond the K-dV limit and these dust-ion-acoustic GS are qualitatively different from the K-dV and mK-dV solitons. It is observed that the basic features of DIASWs are affected by various plasma parameters (viz., electron nonextensivity, negative-to-positive ion number density ratio, electron-to-positive ion number density ratio, electron-to-positive ion temperature ratio, etc.) of the considered plasma system. The findings of our results obtained from this theoretical investigation may be useful in understanding the nonlinear structures and the characteristics of DIASWs propagating in both space and laboratory plasmas.

  16. Ion-acoustic solitons in negative ion plasma with two-electron temperature distributions

    SciTech Connect

    Mishra, M. K.; Tiwari, R. S.; Chawla, J. K.

    2012-06-15

    Ion-acoustic solitons in a warm positive and negative ion species with different masses, concentrations, and charge states with two electron temperature distributions are studied. Using reductive perturbation method, Korteweg de-Vries (KdV) and modified-KdV (m-KdV) equations are derived for the system. The soliton solution of the KdV and m-KdV equations is discussed in detail. It is found that if the ions have finite temperatures, then there exist two types of modes, namely slow and fast ion-acoustic modes. It is also investigated that the parameter determining the nature of soliton (i.e., whether the system will support compressive or rarefactive solitons) is different for slow and fast modes. For the slow mode, the parameter is the relative temperature of the two ion species; whereas for the fast mode, it is the relative concentration of the two ion species. At a critical concentration of negative ions, both compressive and rarefactive solitons coexist. The amplitude and width of the solitons are discussed in detail at critical concentration for m-KdV solitons. The effect of the relative temperature of the two-electron and cold-electron concentration on the characteristics of the solitons are also discussed.

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

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

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

  18. Dressed ion-acoustic solitons in magnetized dusty plasmas

    SciTech Connect

    El-Labany, S. K.; El-Shamy, E. F.; El-Warraki, S. A.

    2009-01-15

    In the present research paper, the characteristics of ion acoustic solitary waves are investigated in hot magnetized dusty plasmas consisting of negatively charged dust grains, positively charged ion fluid, and isothermal electrons. Applying a reductive perturbation theory, a nonlinear Korteweg-de Vries (KdV) equation for the first-order perturbed potential and a linear inhomogeneous KdV-type equation for the second-order perturbed potentials are derived. Stationary solutions of these coupled equations are obtained using a renormalization method. The effects of the external oblique magnetic field, hot ion fluid, and higher-order nonlinearity on the nature of the ion acoustic solitary waves are discussed. The results complement and provide new insights into previously published results on this problem [R. S. Tiwari and M. K. Mishra, Phys. Plasmas 13, 062112 (2006)].

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

    SciTech Connect

    Kumar, Nagendra; Kumar, Vinod; Kumar, Anil

    2008-09-07

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

  20. Ion-acoustic solitary waves in relativistic plasmas

    SciTech Connect

    Das, G.C.; Paul, S.N.

    1985-03-01

    This is a sequel to our earlier study on ion-acoustic waves studied through the augmentation to a modified Korteweg--deVries (K--dV) equation. We have derived a K--dV equation in a plasma, taking account of weakly relativistic effects, and the result shows that the solitary wave does exhibit the relativistic effect in the presence of ion streaming.

  1. Higher-order corrections to dust ion-acoustic soliton in a quantum dusty plasma

    SciTech Connect

    Chatterjee, Prasanta; Das, Brindaban; Mondal, Ganesh; Muniandy, S. V.; Wong, C. S.

    2010-10-15

    Dust ion-acoustic soliton is studied in an electron-dust-ion plasma by employing a two-fluid quantum hydrodynamic model. Ions and electrons are assumed to follow quantum mechanical behaviors in dust background. The Korteweg-de Vries (KdV) equation and higher order contribution to KdV equations are derived using reductive perturbation technique. The higher order contribution is obtained as a higher order inhomogeneous differential equation. The nonsecular solution of the higher order contribution is obtained by using the renormalization method and the particular solution of the inhomogeneous equation is determined using a truncated series solution method. The effects of dust concentration, quantum parameter for ions and electrons, and soliton velocity on the amplitude and width of the dressed soliton are discussed.

  2. Ion-Acoustic Shock Waves in Nonextensive Multi-Ion Plasmas

    NASA Astrophysics Data System (ADS)

    Jannat, N.; Ferdousi, M.; Mamun, A. A.

    2015-10-01

    The nonlinear propagation of ion-acoustic (IA) shock waves (SHWs) in a nonextensive multi-ion plasma system (consisting of inertial positive light ions as well as negative heavy ions, noninertial nonextensive electrons and positrons) has been studied. The reductive perturbation technique has been employed to derive the Burgers equation. The basic properties (polarity, amplitude, width, etc.) of the IA SHWs are found to be significantly modified by the effects of nonextensivity of electrons and positrons, ion kinematic viscosity, temperature ratio of electrons and positrons, etc. It has been observed that SHWs with positive and negative potential are formed depending on the plasma parameters. The findings of our results obtained from this theoretical investigation may be useful in understanding the characteristics of IA SHWs both in laboratory and space plasmas.

  3. Modulational instability of ion-acoustic wave envelopes in magnetized quantum electron-positron-ion plasmas

    SciTech Connect

    Bains, A. S.; Gill, T. S.; Misra, A. P.; Saini, N. S.

    2010-01-15

    The amplitude modulation of quantum ion-acoustic waves (QIAWs) along an external magnetic field is studied in a quantum electron-positron-ion (e-p-i) magnetoplasma. Reductive perturbation technique is used to derive the three-dimensional nonlinear Schroedinger equation which governs the slow modulation of QIAW packets. Accounting for the effects of the electron to ion number density ratio (mu), the normalized ion-cyclotron frequency (omega{sub c}) as well as the ratio (H) of the 'plasmonic energy density' to the Fermi energy, new regimes for the modulational instability of QIAWs are obtained and analyzed. In contrast to one-dimensional unmagnetized e-p-i plasmas, the instability growth rate is shown to suppress with increasing mu or decreasing the values of H. The predicted results could be important for understanding the salient features of modulated QIAW packets in dense astrophysical plasmas as well as to the next generation intense laser solid density plasma experiments.

  4. Dynamics of ion acoustic double layers in a magnetized two-population electrons plasma

    SciTech Connect

    Shahmansouri, M.

    2013-10-15

    The obliquely propagating ion acoustic (IA) double-layers are investigated in a magnetized two population electron plasmas. The extended Korteweg–de Vries equation is derived by using the reductive perturbation technique. The effect of obliqueness (l{sub z}) and magnitude of the external magnetic field (ω{sub ci}), as well as the electron number density (β) on the double-layer profile, is studied, and then the ranges of parameters for which the double-layers exist are investigated in detail. We found that the combined effects of l{sub z}, ω{sub ci}, and β significantly modify the basic properties (viz. amplitude and width) of the IA double-layers.

  5. Cylindrical and Spherical Ion-Acoustic Shock Waves in a Relativistic Degenerate Multi-Ion Plasma

    NASA Astrophysics Data System (ADS)

    Hossen, M. R.; Nahar, L.; Mamun, A. A.

    2014-12-01

    A rigorous theoretical investigation has been made to study the existence and basic features of the ion-acoustic (IA) shock structures in an unmagnetized, collisionless multi-ion plasma system (containing degenerate electron fluids, inertial positively as well as negatively charged ions, and arbitrarily charged static heavy ions). This investigation is valid for both non-relativistic and ultra-relativistic limits. The reductive perturbation technique has been employed to derive the modified Burgers equation. The solution of this equation has been numerically examined to study the basic properties of shock structures. The basic features (speed, amplitude, width, etc.) of these electrostatic shock structures have been briefly discussed. The basic properties of the IA shock waves are found to be significantly modified by the effects of arbitrarily charged static heavy ions and the plasma particle number densities. The implications of our results in space and interstellar compact objects like white dwarfs, neutron stars, black holes, and so on have been briefly discussed.

  6. Evolution of nonlinear dust-ion-acoustic waves in an inhomogeneous plasma

    NASA Astrophysics Data System (ADS)

    Xiao, De-long; Ma, J. X.; Li, Yang-fang; Xia, Yinhua; Yu, M. Y.

    2006-05-01

    The propagation of nonlinear dust-ion-acoustic waves in an inhomogeneous dusty plasma is studied. At small but finite amplitudes, the wave evolution is governed by a modified Korteweg-deVries Burgers equation, whose coefficients are space dependent. The properties of the evolution equation are analyzed and the behavior of the corresponding shock and soliton solutions is numerically studied. If dust-charge perturbation is neglected, there exists a zero-nonlinearity point where the coefficient of the nonlinear term changes from negative to positive. At that point the nonlinear wave also undergoes structural deformation. If the dust-charge perturbation is taken into account, the zero-nonlinearity point may not appear and the soliton or shock wave will retain its form during the propagation.

  7. Evolution of nonlinear dust-ion-acoustic waves in an inhomogeneous plasma

    SciTech Connect

    Xiao Delong; Ma, J.X.; Li Yangfang; Xia Yinhua; Yu, M.Y.

    2006-05-15

    The propagation of nonlinear dust-ion-acoustic waves in an inhomogeneous dusty plasma is studied. At small but finite amplitudes, the wave evolution is governed by a modified Korteweg-deVries Burgers equation, whose coefficients are space dependent. The properties of the evolution equation are analyzed and the behavior of the corresponding shock and soliton solutions is numerically studied. If dust-charge perturbation is neglected, there exists a zero-nonlinearity point where the coefficient of the nonlinear term changes from negative to positive. At that point the nonlinear wave also undergoes structural deformation. If the dust-charge perturbation is taken into account, the zero-nonlinearity point may not appear and the soliton or shock wave will retain its form during the propagation.

  8. Linear and nonlinear dust ion acoustic waves using the two-fluid quantum hydrodynamic model

    NASA Astrophysics Data System (ADS)

    Masood, W.; Mushtaq, A.; Khan, R.

    2007-12-01

    The linear and nonlinear properties of a dust ion acoustic wave (DIAW) propagating in an electron-dust-ion plasma are investigated from both analytical and numerical perspectives by employing the two-fluid quantum hydrodynamic model. Ions and dust are assumed to be mobile while electrons are considered to be inertialess. Furthermore, quantum effects (diffraction as well as statistic) due to ions and electrons are incorporated. It is emphasized that the linear dispersion characteristics of the DIAW depend on the quantum diffraction effects of both ions and electrons as well as on the dust concentration. The one-dimensional Korteweg-deVries equation is derived for the quantum DIAW using the reductive perturbative technique. It is observed that the quantum electron diffraction term shrinks the width while the dust concentration enhances both the amplitude and width of the soliton.

  9. Linear and nonlinear dust ion acoustic waves using the two-fluid quantum hydrodynamic model

    SciTech Connect

    Masood, W.; Mushtaq, A.; Khan, R.

    2007-12-15

    The linear and nonlinear properties of a dust ion acoustic wave (DIAW) propagating in an electron-dust-ion plasma are investigated from both analytical and numerical perspectives by employing the two-fluid quantum hydrodynamic model. Ions and dust are assumed to be mobile while electrons are considered to be inertialess. Furthermore, quantum effects (diffraction as well as statistic) due to ions and electrons are incorporated. It is emphasized that the linear dispersion characteristics of the DIAW depend on the quantum diffraction effects of both ions and electrons as well as on the dust concentration. The one-dimensional Korteweg-deVries equation is derived for the quantum DIAW using the reductive perturbative technique. It is observed that the quantum electron diffraction term shrinks the width while the dust concentration enhances both the amplitude and width of the soliton.

  10. Nonlinear ion acoustic excitations in relativistic degenerate, astrophysical electron-positron-ion plasmas

    NASA Astrophysics Data System (ADS)

    Rahman, Ata-Ur; Ali, S.; Mushtaq, A.; Qamar, A.; Qamar

    2013-10-01

    The dynamics and propagation of ion acoustic (IA) waves are considered in an unmagnetized collisionless plasma, whose constituents are the relativistically degenerate electrons and positrons as well as the inertial cold ions. At a first step, a linear dispersion relation for IA waves is derived and analysed numerically. For nonlinear analysis, the reductive perturbation technique is used to derive a Korteweg-deVries equation, which admits a localized wave solution in the presence of relativistic degenerate electrons and positrons. It is shown that only compressive IA solitary waves can propagate, whose amplitude, width and phase velocity are significantly modified due to the positron concentration. The latter also strongly influences all the relativistic plasma parameters. Our present analysis is aimed to understand collective interactions in dense astrophysical objects, e.g. white dwarfs, where the lighter species electrons and positrons are taken as relativistically degenerate.

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

    NASA Astrophysics Data System (ADS)

    Emadi, E.; Zahed, H.

    2016-08-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1979-01-01

    The paper presents a study of the relationship between the interplanetary ion acoustic waves detected by Helios and the macroscopic and microscopic characteristics of the solar wind plasma. Two major mechanisms, an electron heat flux instability and a double-ion beam instability, are considered for generating the ion-acoustic-like waves observed in the solar wind. The results provide support to both mechanisms for generating the solar wind ion acoustic waves, although each mechanism has problems under certain conditions.

  13. Cylindrical and spherical ion acoustic waves in a plasma with nonthermal electrons and warm ions

    SciTech Connect

    Sahu, Biswajit; Roychoudhury, Rajkumar

    2005-05-15

    Using the reductive perturbation technique, nonlinear cylindrical and spherical Korteweg-de Vries (KdV) and modified KdV equations are derived for ion acoustic waves in an unmagnetized plasma consisting of warm adiabatic ions and nonthermal electrons. The effects of nonthermally distributed electrons on cylindrical and spherical ion acoustic waves are investigated. It is found that the nonthermality has a very significant effect on the nature of ion acoustic waves.

  14. Ion acoustic shock wave in collisional equal mass plasma

    SciTech Connect

    Adak, Ashish; Ghosh, Samiran; Chakrabarti, Nikhil

    2015-10-15

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

  15. Ion acoustic shock wave in collisional equal mass plasma

    NASA Astrophysics Data System (ADS)

    Adak, Ashish; Ghosh, Samiran; Chakrabarti, Nikhil

    2015-10-01

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

  16. Hybrid (Vlasov-Fluid) simulation of ion-acoustic soliton chain formation and validity of Korteweg de-Vries model

    SciTech Connect

    Aminmansoor, F.; Abbasi, H.

    2015-08-15

    The present paper is devoted to simulation of nonlinear disintegration of a localized perturbation into ion-acoustic solitons train in a plasma with hot electrons and cold ions. A Gaussian initial perturbation is used to model the localized perturbation. For this purpose, first, we reduce fluid system of equations to a Korteweg de-Vries equation by the following well-known assumptions. (i) On the ion-acoustic evolution time-scale, the electron velocity distribution function (EVDF) is assumed to be stationary. (ii) The calculation is restricted to small amplitude cases. Next, in order to generalize the model to finite amplitudes cases, the evolution of EVDF is included. To this end, a hybrid code is designed to simulate the case, in which electrons dynamics is governed by Vlasov equation, while cold ions dynamics is, like before, studied by the fluid equations. A comparison between the two models shows that although the fluid model is capable of demonstrating the general features of the process, to have a better insight into the relevant physics resulting from the evolution of EVDF, the use of kinetic treatment is of great importance.

  17. Particle-in-cell simulation of the head-on collision between two ion acoustic solitary waves in plasmas

    SciTech Connect

    Qi, Xin; Xu, Yan-xia; Duan, Wen-shan E-mail: lyang@impcas.ac.cn; Zhang, Ling-yu; Yang, Lei E-mail: lyang@impcas.ac.cn

    2014-08-15

    The head-on collision of two ion acoustic solitary waves in plasmas composed of hot electrons and cold ions has been studied by using the Poincare-Lighthill-Kuo (PLK) perturbation method and one-dimensional Particle-in-Cell (PIC) simulation. Then the phase lags of ion acoustic solitary waves (IASWs) obtained from the two approaches have been compared and discussed. It has been found that: if the amplitudes of both the colliding IASWs are small enough, the phase lags obtained from PLK method are in good agreement with those obtained from PIC simulation. As the amplitudes of IASWs increase, the phase lags from PIC simulation become smaller than the analytical ones from PLK method. Besides, the PIC simulation shows the phase lag of an IASW involved in collision depends not only on the characteristics of the wave it collides with but also on itself, which disagrees with the prediction of the PLK method. Finally, the application scopes of the PLK method in studying both the single IASW and the head-on collisions of IASWs have been studied and discussed, and the latter turns out to be more strict.

  18. Particle-in-cell simulation of the head-on collision between two ion acoustic solitary waves in plasmas

    NASA Astrophysics Data System (ADS)

    Qi, Xin; Xu, Yan-xia; Duan, Wen-shan; Zhang, Ling-yu; Yang, Lei

    2014-08-01

    The head-on collision of two ion acoustic solitary waves in plasmas composed of hot electrons and cold ions has been studied by using the Poincare-Lighthill-Kuo (PLK) perturbation method and one-dimensional Particle-in-Cell (PIC) simulation. Then the phase lags of ion acoustic solitary waves (IASWs) obtained from the two approaches have been compared and discussed. It has been found that: if the amplitudes of both the colliding IASWs are small enough, the phase lags obtained from PLK method are in good agreement with those obtained from PIC simulation. As the amplitudes of IASWs increase, the phase lags from PIC simulation become smaller than the analytical ones from PLK method. Besides, the PIC simulation shows the phase lag of an IASW involved in collision depends not only on the characteristics of the wave it collides with but also on itself, which disagrees with the prediction of the PLK method. Finally, the application scopes of the PLK method in studying both the single IASW and the head-on collisions of IASWs have been studied and discussed, and the latter turns out to be more strict.

  19. Hybrid (Vlasov-Fluid) simulation of ion-acoustic soliton chain formation and validity of Korteweg de-Vries model

    NASA Astrophysics Data System (ADS)

    Aminmansoor, F.; Abbasi, H.

    2015-08-01

    The present paper is devoted to simulation of nonlinear disintegration of a localized perturbation into ion-acoustic solitons train in a plasma with hot electrons and cold ions. A Gaussian initial perturbation is used to model the localized perturbation. For this purpose, first, we reduce fluid system of equations to a Korteweg de-Vries equation by the following well-known assumptions. (i) On the ion-acoustic evolution time-scale, the electron velocity distribution function (EVDF) is assumed to be stationary. (ii) The calculation is restricted to small amplitude cases. Next, in order to generalize the model to finite amplitudes cases, the evolution of EVDF is included. To this end, a hybrid code is designed to simulate the case, in which electrons dynamics is governed by Vlasov equation, while cold ions dynamics is, like before, studied by the fluid equations. A comparison between the two models shows that although the fluid model is capable of demonstrating the general features of the process, to have a better insight into the relevant physics resulting from the evolution of EVDF, the use of kinetic treatment is of great importance.

  20. Modified ion-acoustic solitary waves in plasmas with field-aligned shear flows

    SciTech Connect

    Saleem, H.; Haque, Q.

    2015-08-15

    The nonlinear dynamics of ion-acoustic waves is investigated in a plasma having field-aligned shear flow. A Korteweg-deVries-type nonlinear equation for a modified ion-acoustic wave is obtained which admits a single pulse soliton solution. The theoretical result has been applied to solar wind plasma at 1 AU for illustration.

  1. Modified ion-acoustic solitary waves in plasmas with field-aligned shear flows

    NASA Astrophysics Data System (ADS)

    Saleem, H.; Ali, S.; Haque, Q.

    2015-08-01

    The nonlinear dynamics of ion-acoustic waves is investigated in a plasma having field-aligned shear flow. A Koeteweg-deVries-type nonlinear equation for a modified ion-acoustic wave is obtained which admits a single pulse soliton solution. The theoretical result has been applied to solar wind plasma at 1 AU for illustration.

  2. Equation-free Modeling of Ion Acoustic Wave with Particle Trapping

    NASA Astrophysics Data System (ADS)

    Stantchev, George

    2005-10-01

    Recently, Shay et al.[1] have successfully implemented equation-free projective integraion methods to simulate the propagation and steepening of a 1D ion acoustic wave. For the forward extrapolation step they have been using only a small number of lower moments of the probability density function (PDF) based on the assumption that the distribution would remain Maxwellian at all times. This however is no longer valid in many interesting situations, in particular for the case of particle trapping. To solve this problem we propose a generalization of Shay's algorithm to allow for tracking of an arbitrary PDF. We estimate the PDF at each micro-time step using statistical wavelet analysis. The resulting vectors of wavelet coefficents are used for forward extrapolation in time to obtain a multi-scale representation of the projected PDF after a coarse time step. An optimal wavelet basis is selected through adaptive refinement at the beginning of each microscopic simulation sequence. We discuss the application of this technique to the 1D acoustic wave problem with particle trapping. [1] M. Shay, J. Drake, W. Dorland, Multiscale modeling of plasmas via equation-free projective integration, in preparation

  3. Ion-acoustic solitary waves and their multi-dimensional instability in a magnetized degenerate plasma

    SciTech Connect

    Haider, M. M.; Mamun, A. A.

    2012-10-15

    A rigorous theoretical investigation has been made on Zakharov-Kuznetsov (ZK) equation of ion-acoustic (IA) solitary waves (SWs) and their multi-dimensional instability in a magnetized degenerate plasma which consists of inertialess electrons, inertial ions, negatively, and positively charged stationary heavy ions. The ZK equation is derived by the reductive perturbation method, and multi-dimensional instability of these solitary structures is also studied by the small-k (long wave-length plane wave) perturbation expansion technique. The effects of the external magnetic field are found to significantly modify the basic properties of small but finite-amplitude IA SWs. The external magnetic field and the propagation directions of both the nonlinear waves and their perturbation modes are found to play a very important role in changing the instability criterion and the growth rate of the unstable IA SWs. The basic features (viz., amplitude, width, instability, etc.) and the underlying physics of the IA SWs, which are relevant to space and laboratory plasma situations, are briefly discussed.

  4. Experimental evidence of ion acoustic soliton chain formation and validation of nonlinear fluid theory

    SciTech Connect

    Kakad, Amar; Omura, Yoshiharu; Kakad, Bharati

    2013-06-15

    We perform one-dimensional fluid simulation of ion acoustic (IA) solitons propagating parallel to the magnetic field in electron-ion plasmas by assuming a large system length. To model the initial density perturbations (IDP), we employ a KdV soliton type solution. Our simulation demonstrates that the generation mechanism of IA solitons depends on the wavelength of the IDP. The short wavelength IDP evolve into two oppositely propagating identical IA solitons, whereas the long wavelength IDP develop into two indistinguishable chains of multiple IA solitons through a wave breaking process. The wave breaking occurs close to the time when electrostatic energy exceeds half of the kinetic energy of the electron fluid. The wave breaking amplitude and time of its initiation are found to be dependent on characteristics of the IDP. The strength of the IDP controls the number of IA solitons in the solitary chains. The speed, width, and amplitude of IA solitons estimated during their stable propagation in the simulation are in good agreement with the nonlinear fluid theory. This fluid simulation is the first to confirm the validity of the general nonlinear fluid theory, which is widely used in the study of solitary waves in laboratory and space plasmas.

  5. Weakly dissipative dust-ion acoustic wave modulation

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

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

  6. Ion acoustic waves in a multi-ion plasma.

    NASA Technical Reports Server (NTRS)

    Fried, B. D.; White, R. B.; Samec, T. K.

    1971-01-01

    An exact treatment of the multispecies ion acoustic dispersion relation is given for an argon/helium plasma. Phase velocity and damping are obtained as a function of ion-electron temperature ratio and relative densities of the two species. There are two important modes in the plasma, with quite different phase velocities, which are referred to as principal heavy ion mode and principal light ion mode. Which of these is dominant depends on the relative densities of the two components, but, in general, the light ion mode becomes important for surprisingly small light ion contamination. Approximate analytic expressions are derived from damping rates and phase velocities and their domains of validity are investigated. Relevance of the results for the investigation of collisionless shocks is discussed.

  7. Generation of coherent ion acoustic solitary waves in inhomogeneous plasmas by an odd eigenmode of electron holes

    NASA Astrophysics Data System (ADS)

    Dokgo, Kyunghwan; Woo, Minho; Choi, Cheong-Rim; Min, Kyoung-Wook; Hwang, Junga

    2016-09-01

    Generation of coherent ion acoustic solitary waves (IASWs) in inhomogeneous plasmas by an odd eigenmode (OEM) of electron holes (EHs) is investigated using 1D electrostatic particle-in-cell (PIC) simulations. The OEM oscillates at a frequency comparable to the trapped electron bouncing frequency, as also demonstrated by Lewis' theoretical formalism about the linear eigenmode in Bernstein-Greene-Kruskal (BGK) equilibrium. The density gradient in the inhomogeneous plasmas causes asymmetry in the EH potential structure associated with the OEM, whose amplitude grows rapidly as it propagates through the density gradient region. As the ions interact with this asymmetric potential, which oscillates slowly enough for the ions to respond, they are ejected to the lower density side with a larger potential amplitude, forming a chain of IASWs coherently with the oscillation of the OEM.

  8. Properties of cylindrical and spherical heavy ion-acoustic solitary and shock structures in a multispecies plasma with superthermal electrons

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

    A theoretical investigation on heavy ion-acoustic (HIA) solitary and shock structures has been accomplished in an unmagnetized multispecies plasma consisting of inertialess kappa-distributed superthermal electrons, Boltzmann light ions, and adiabatic positively charged inertial heavy ions. Using the reductive perturbation technique, the nonplanar (cylindrical and spherical) Kortewg-de Vries (KdV) and Burgers equations have been derived. The solitary and shock wave solutions of the KdV and Burgers equations, respectively, have been numerically analyzed. The effects of superthermality of electrons, adiabaticity of heavy ions, and nonplanar geometry, which noticeably modify the basic features (viz. polarity, amplitude, phase speed, etc.) of small but finite amplitude HIA solitary and shock structures, have been carefully investigated. The HIA solitary and shock structures in nonplanar geometry have been found to distinctly differ from those in planar geometry. Novel features of our present attempt may contribute to the physics of nonlinear electrostatic perturbation in astrophysical and laboratory plasmas.

  9. Head-on collision of two dust ion acoustic solitary waves in a weakly relativistic multicomponent superthermal plasma

    NASA Astrophysics Data System (ADS)

    Saini, N. S.; Singh, Kuldeep

    2016-10-01

    A head-on collision between two dust ion acoustic solitary waves (DIASWs) travelling in the opposite direction in a weakly relativistic plasma composed of four distinct particle populations, namely, weakly relativistic ion fluid, superthermal electrons as well as positrons, and immobile dust, is investigated. By employing extended Poincaré-Lighthill-Kuo method, two Korteweg-de Vries (KdV) equations are derived. The analytical phase shift after a head-on collision of two dust ion acoustic (DIA) solitary waves is also obtained. The combined effects of relativistic factor (β), electron to positron temperature ratio (α), ion to electron temperature ratio (σ), positron to electron density ratio (P), dust density ratio (d), and superthermality of electrons as well as positrons (via κ) on the phase shifts are numerically studied. All these physical parameters have also changed the potential amplitude and the width of colliding solitary waves. It is found that the presence of superthermal electrons as well as positrons and dust grains has emphatic influence on the phase shifts and potential pulse profiles of compressive DIA solitons. Our results are general and may be helpful in understanding a head-on collision between two DIASWs in astrophysical and laboratory plasmas, especially the interaction of pulsar relativistic winds with supernova ejecta that produces the superthermal particles and relativistic ions.

  10. Fluid simulation of dispersive and nondispersive ion acoustic waves in the presence of superthermal electrons

    NASA Astrophysics Data System (ADS)

    Lotekar, Ajay; Kakad, Amar; Kakad, Bharati

    2016-10-01

    One-dimensional fluid simulation is performed for the unmagnetized plasma consisting of cold fluid ions and superthermal electrons. Such a plasma system supports the generation of ion acoustic (IA) waves. A standard Gaussian type perturbation is used in both electron and ion equilibrium densities to excite the IA waves. The evolutionary profiles of the IA waves are obtained by varying the superthermal index and the amplitude of the initial perturbation. This simulation demonstrates that the amplitude of the initial perturbation and the superthermal index play an important role in determining the time evolution and the characteristics of the generated IA waves. The initial density perturbation in the system creates charge separation that drives the finite electrostatic potential in the system. This electrostatic potential later evolves into the dispersive and nondispersive IA waves in the simulation system. The density perturbation with the amplitude smaller than 10% of the equilibrium plasma density evolves into the dispersive IA waves, whereas larger density perturbations evolve into both dispersive and nondispersive IA waves for lower and higher superthermal index. The dispersive IA waves are the IA oscillations that propagate with constant ion plasma frequency, whereas the nondispersive IA waves are the IA solitary pulses (termed as IA solitons in the stability region) that propagate with the constant wave speed. The characteristics of the stable nondispersive IA solitons are found to be consistent with the nonlinear fluid theory. To the best of our knowledge, this is the first fluid simulation study that has considered the superthermal distributions for the plasma species to model the electrostatic solitary waves.

  11. A study of the nonlinear aerodynamics of bodies in nonplanar motion. Ph.D. Thesis - Stanford Univ., Calif.; [numerical analysis of aerodynamic force and moment systems during large amplitude, arbitrary motions

    NASA Technical Reports Server (NTRS)

    Schiff, L. B.

    1974-01-01

    Concepts from the theory of functionals are used to develop nonlinear formulations of the aerodynamic force and moment systems acting on bodies in large-amplitude, arbitrary motions. The analysis, which proceeds formally once the functional dependence of the aerodynamic reactions upon the motion variables is established, ensures the inclusion, within the resulting formulation, of pertinent aerodynamic terms that normally are excluded in the classical treatment. Applied to the large-amplitude, slowly varying, nonplanar motion of a body, the formulation suggests that the aerodynamic moment can be compounded of the moments acting on the body in four basic motions: steady angle of attack, pitch oscillations, either roll or yaw oscillations, and coning motion. Coning, where the nose of the body describes a circle around the velocity vector, characterizes the nonplanar nature of the general motion.

  12. Dust-ion-acoustic Gardner solitons in a dusty plasma with bi-Maxwellian electrons

    SciTech Connect

    Masud, M. M.; Asaduzzaman, M.; Mamun, A. A.

    2012-10-15

    The nonlinear propagation of dust-ion-acoustic (DIA) waves in a dusty plasma with bi-Maxwellian electrons, namely, lower and higher temperature electrons (composed of negatively charged stationary dust, inertial ions, and non-inertial two-temperature-electrons) is investigated by deriving the Gardner equation using the reductive perturbation technique. The basic features (amplitude, width, etc.) of the hump (positive potential) and dip (negative potential) shaped DIA solitons (Gardner solitons, i.e., GSs) are found to exist beyond the Korteweg-de Vries (K-dV) limit. These DIA-GSs are qualitatively different from the K-dV and modified K-dV solitons. It is also shown that depending on the parameter {sigma} (where {sigma}=T{sub e1}/T{sub e2}, T{sub e1} and T{sub e2} being the temperatures of two distinct electrons and T{sub e1} Much-Less-Than T{sub e2}), the DIA-GSs exhibit hump and dip shape solitary structures. The implications of our results in understanding the localized nonlinear electrostatic perturbations observed in double-plasma machines, rf discharge plasma, noctilucent cloud region in Earths atmosphere, etc., where population of two thermal electrons can significantly dominate the wave dynamics, are also briefly addressed.

  13. Linear and nonlinear heavy ion-acoustic waves in a strongly coupled plasma

    SciTech Connect

    Ema, S. A. Mamun, A. A.; Hossen, M. R.

    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.

  14. Electrostatic ion-acoustic-like instabilities in the solar wind with a backstreaming alpha particle beam

    SciTech Connect

    Gomberoff, L.; Gomberoff, K.; Deutsch, A.

    2010-06-15

    Nonlinear electrostatic instabilities have been shown to occur frequently and under very different conditions in plasma with two ion beams such as the fast solar wind. These instabilities can be triggered when the phase velocity of electrostatic ion-acoustic waves propagating forward and backward relative to the interplanetary magnetic field overlaps due to the presence of a finite amplitude of circularly polarized wave. The instabilities can be triggered by waves supported by the same ion component, or by waves supported by different ion components. By assuming a beam of alpha particles moving backward relative to the external magnetic field, as observed in some events in the fast solar wind, it is shown that a very small negative drift velocity of the alpha particle beam relative to the core plasma--a few percent of the local Alfven velocity--can trigger a very rich variety of nonlinear electrostatic acousticlike instabilities. Their growth rates can be rather large and they persist for larger negative alpha particles drift velocities and temperatures.

  15. Ion-acoustic Gardner solitons in a four-component nonextensive multi-ion plasma

    NASA Astrophysics Data System (ADS)

    Jannat, N.; Ferdousi, M.; Mamun, A. A.

    2016-07-01

    The nonlinear propagation of ion-acoustic (IA) solitary waves (SWs) in a four-component non-extensive multi-ion plasma system containing inertial positively charged light ions, negatively charged heavy ions, as well as noninertial nonextensive electrons and positrons has been theoretically investigated. The reductive perturbation method has been employed to derive the nonlinear equations, namely, Korteweg-deVries (KdV), modified KdV (mKdV), and Gardner equations. The basic features (viz. polarity, amplitude, width, etc.) of Gardner solitons are found to exist beyond the KdV limit and these IA Gardner solitons are qualitatively different from the KdV and mKdV solitons. It is observed that the basic features of IA SWs are modified by various plasma parameters (viz. electron and positron nonextensivity, electron number density to ion number density, and electron temperature to positron temperature, etc.) of the considered plasma system. The results obtained from this theoretical investigation may be useful in understanding the basic features of IA SWs propagating in both space and laboratory plasmas.

  16. Modulational instability of ion-acoustic wave envelopes in magnetized quantum electron-positron-ion plasmas

    NASA Astrophysics Data System (ADS)

    Bains, A. S.; Misra, A. P.; Saini, N. S.; Gill, T. S.

    2010-01-01

    The amplitude modulation of quantum ion-acoustic waves (QIAWs) along an external magnetic field is studied in a quantum electron-positron-ion (e-p-i) magnetoplasma. Reductive perturbation technique is used to derive the three-dimensional nonlinear Schrödinger equation which governs the slow modulation of QIAW packets. Accounting for the effects of the electron to ion number density ratio (μ), the normalized ion-cyclotron frequency (ωc) as well as the ratio (H) of the "plasmonic energy density" to the Fermi energy, new regimes for the modulational instability of QIAWs are obtained and analyzed. In contrast to one-dimensional unmagnetized e-p-i plasmas, the instability growth rate is shown to suppress with increasing μ or decreasing the values of H. The predicted results could be important for understanding the salient features of modulated QIAW packets in dense astrophysical plasmas as well as to the next generation intense laser solid density plasma experiments.

  17. Effect of Bohm quantum potential in the propagation of ion-acoustic waves in degenerate plasmas

    NASA Astrophysics Data System (ADS)

    Hasan, M. M.; Hossen, M. A.; Rafat, A.; Mamun, A. A.

    2016-10-01

    A theoretical investigation has been carried out on the propagation of the ion-acoustic (IA) waves in a relativistic degenerate plasma containing relativistic degenerate electron and positron fluids in the presence of inertial non-relativistic light ion fluid. The Korteweg-de Vries (K-dV), modified K-dV (mK-dV), and mixed mK-dV (mmK-dV) equations are derived by adopting the reductive perturbation method. In order to analyze the basic features (phase speed, amplitude, width, etc.) of the IA solitary waves (SWs), the SWs solutions of the K-dV, mK-dV, and mmK-dV are numerically analyzed. It is found that the degenerate pressure, inclusion of the new phenomena like the Fermi temperatures and quantum mechanical effects (arising due to the quantum diffraction) of both electrons and positrons, number densities, etc., of the plasma species remarkably change the basic characteristics of the IA SWs which are found to be formed either with positive or negative potential. The implication of our results in explaining different nonlinear phenomena in astrophysical compact objects, e.g., white dwarfs, neutron stars, etc., and laboratory plasmas like intense laser-solid matter interaction experiments, etc., are mentioned.

  18. Linear and nonlinear heavy ion-acoustic waves in a strongly coupled plasma

    NASA Astrophysics Data System (ADS)

    Ema, S. A.; Hossen, M. R.; Mamun, A. A.

    2015-09-01

    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.

  19. Propagation and stability of quantum dust-ion-acoustic shock waves in planar and nonplanar geometry

    NASA Astrophysics Data System (ADS)

    Masood, W.; Siddiq, M.; Nargis, Shahida; Mirza, Arshad M.

    2009-01-01

    Dust-ion-acoustic (DIA) shock waves are studied in an unmagnetized quantum plasma consisting of electrons, ions, and dust by employing the quantum hydrodynamic (QHD) model. In this context, a Korteweg-deVries-Burger (KdVB) equation is derived by employing the small amplitude perturbation expansion method. The dissipation is introduced by taking into account the kinematic viscosity among the plasma constituents. It is found that the strength of the quantum DIA shock wave is maximum for spherical, intermediate for cylindrical, and minimum for the planar geometry. The effects of quantum Bohm potential, dust concentration, and kinematic viscosity on the quantum DIA shock structure are also investigated. The temporal evolution of DIA KdV solitons and Burger shocks are also studied by putting the dissipative and dispersive coefficients equal to zero, respectively. The effects of the quantum Bohm potential on the stability of the DIA shock is also investigated. The present investigation may be beneficial to understand the dissipative and dispersive processes that may occur in the quantum dusty plasmas found in microelectronic devices as well as in astrophysical plasmas.

  20. Propagation and stability of quantum dust-ion-acoustic shock waves in planar and nonplanar geometry

    SciTech Connect

    Masood, W.; Siddiq, M.; Nargis, Shahida; Mirza, Arshad M.

    2009-01-15

    Dust-ion-acoustic (DIA) shock waves are studied in an unmagnetized quantum plasma consisting of electrons, ions, and dust by employing the quantum hydrodynamic (QHD) model. In this context, a Korteweg-deVries-Burger (KdVB) equation is derived by employing the small amplitude perturbation expansion method. The dissipation is introduced by taking into account the kinematic viscosity among the plasma constituents. It is found that the strength of the quantum DIA shock wave is maximum for spherical, intermediate for cylindrical, and minimum for the planar geometry. The effects of quantum Bohm potential, dust concentration, and kinematic viscosity on the quantum DIA shock structure are also investigated. The temporal evolution of DIA KdV solitons and Burger shocks are also studied by putting the dissipative and dispersive coefficients equal to zero, respectively. The effects of the quantum Bohm potential on the stability of the DIA shock is also investigated. The present investigation may be beneficial to understand the dissipative and dispersive processes that may occur in the quantum dusty plasmas found in microelectronic devices as well as in astrophysical plasmas.

  1. Ion-acoustic enhancements generated by beam-plasma instability in an auroral cavity

    NASA Astrophysics Data System (ADS)

    Ziebell, L. F.; Yoon, P. H.; Pavan, J.; Gaelzer, R.

    2011-03-01

    This article demonstrates the generation of enhanced ion-acoustic waves by beam-plasma instability in a density cavity. The self-consistent equations of weak turbulence theory that include quasi-linear, decay, and scattering processes as well as convective and dispersive effects are numerically solved for a one-dimensional density cavity. It is shown that significant enhancements of ion-acoustic waves occur in the presence of counterstreaming electron beams and that the enhanced ion-acoustic waves are initially localized near the center of the density cavity at large wavelengths. Later in the evolution, the enhancement in the spectrum of ion-acoustic waves spreads out toward the edges of the cavity, with a shift to smaller wavelengths, while the enhancement near the center of the cavity tends to decrease in magnitude. The significance of the present findings is discussed.

  2. Filamentation instability of nonextensive current-driven plasma in the ion acoustic frequency range

    SciTech Connect

    Khorashadizadeh, S. M. Rastbood, E.; Niknam, A. R.

    2014-12-15

    The filamentation and ion acoustic instabilities of nonextensive current-driven plasma in the ion acoustic frequency range have been studied using the Lorentz transformation formulas. Based on the kinetic theory, the possibility of filamentation instability and its growth rate as well as the ion acoustic instability have been investigated. The results of the research show that the possibility and growth rate of these instabilities are significantly dependent on the electron nonextensive parameter and drift velocity. Besides, the increase of electrons nonextensive parameter and drift velocity lead to the increase of the growth rates of both instabilities. In addition, the wavelength region in which the filamentation instability occurs is more stretched in the presence of higher values of drift velocity and nonextensive parameter. Finally, the results of filamentation and ion acoustic instabilities have been compared and the conditions for filamentation instability to be dominant mode of instability have been presented.

  3. Ion acoustic solitons in a solar wind magnetoplasma with Kappa distributed electrons

    NASA Astrophysics Data System (ADS)

    Devanandhan, Selvaraj; Singh, Satyavir; Singh Lakhina, Gurbax; Sreeraj, T.

    2016-07-01

    In many space plasma environments, the velocity distribution of particles often deviates from Maxwellian and is well-modelled by a kappa distribution function. We have analyzed the ion acoustic soliton in a magnetized consisting of plasma Protons, Helium ions, an electron beam and superthermal hot electrons following kappa distribution function. Under the assumption of weak nonlinearity, the ion-acoustic solitons are described by the Korteweg-de-Vries-Zakharov-Kuznetsov (KdV-ZK) equation. The solution of KdV-ZK equation is used to model the characteristics of the ion acoustic solitary waves in a solar wind magnetoplasma observed at 1 AU. We have found both slow and fast ion acoustic solitons in our study. It is found that the superthermality of hot electrons greatly influence the existence regime of the solitary waves. The numerical results of this study to explain solar wind observations will be discussed in detail.

  4. Time evolution of ion-acoustic double layers in an unmagnetized plasma

    SciTech Connect

    Bharuthram, R.; Momoniat, E.; Mahomed, F.; Singh, S. V.; Islam, M. K.

    2008-08-15

    Ion-acoustic double layers are examined in an unmagnetized, three-component plasma consisting of cold ions and two temperature electrons. Both of the electrons are considered to be Boltzmann distributed and the ions follow the usual fluid dynamical equations. Using the method of characteristics, a time-dependent solution for ion-acoustic double layers is obtained. Results of the findings may have important consequences for the real time satellite observations in the space environment.

  5. Dust-ion-acoustic wave oscillation in metallic multiwalled carbon nanotubes

    SciTech Connect

    Fathalian, Ali; Nikjo, Shahram

    2010-10-15

    In this paper, a charged multiwalled carbon nanotube (MWCNT), which is surrounded by charged nanoparticles, is modeled as a cylindrical shell of electron-ion-dust plasma. By employing the classical electrodynamics formulations and linearized hydrodynamic model, the dispersion relation of the dust-ion-acoustic wave oscillations in the composed system is investigated. We obtain a new low-frequency electrostatic excitation in the MWCNTs, i.e., dust-ion-acoustic wave oscillations.

  6. Ion acoustic solitons in a plasma with finite temperature drifting ions: Limit on ion drift velocity

    SciTech Connect

    Malik, H.K.; Singh, S.; Dahiya, R.P. )

    1994-05-01

    Propagation of ion acoustic solitons in a plasma consisting of finite temperature drifting ions and nondrifting electrons has been studied. It is shown that in addition to the electron inertia and weak relativistic effects, the ion temperature also modifies the soliton behavior. By including the finite ion temperature, limit for the ion drift velocity [ital u][sub 0] for which the ion acoustic solitons are possible, is obtained. The solitons can exist for [ital v][sub [ital Te

  7. Filamentation instability of current-driven dust ion-acoustic waves in a collisional dusty plasma

    SciTech Connect

    Niknam, A. R.; Haghtalab, T.; Khorashadizadeh, S. M.

    2011-11-15

    A theoretical investigation has been made of the dust ion-acoustic filamentation instability in an unmagnetized current-driven dusty plasma by using the Lorentz transformation formulas. The effect of collision between the charged particles with neutrals and their thermal motion on this instability is considered. Developing the filamentation instability of the current-driven dust ion-acoustic wave allows us to determine the period and the establishment time of the filamentation structure and threshold for instability development.

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

    SciTech Connect

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

    2011-01-15

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

  9. Existence domains of arbitrary amplitude nonlinear structures in two-electron temperature space plasmas. II. High-frequency electron-acoustic solitons

    SciTech Connect

    Maharaj, S. K.; Bharuthram, R.; Singh, S. V.; Lakhina, G. S.

    2012-12-15

    A three-component plasma model composed of ions, cool electrons, and hot electrons is adopted to investigate the existence of large amplitude electron-acoustic solitons not only for the model for which inertia and pressure are retained for all plasma species which are assumed to be adiabatic but also neglecting inertial effects of the hot electrons. Using the Sagdeev potential formalism, the Mach number ranges supporting the existence of large amplitude electron-acoustic solitons are presented. The limitations on the attainable amplitudes of electron-acoustic solitons having negative potentials are attributed to a number of different physical reasons, such as the number density of either the cool electrons or hot electrons ceases to be real valued beyond the upper Mach number limit, or, alternatively, a negative potential double layer occurs. Electron-acoustic solitons having positive potentials are found to be supported only if inertial effects of the hot electrons are retained and these are found to be limited only by positive potential double layers.

  10. Large amplitude nonlinear structures in the nighttime polar mesosphere

    NASA Astrophysics Data System (ADS)

    Maharaj, Shimul K.; Bharuthram, Ramashwar; Singh Lakhina, Gurbax; Muralikrishna, Polinaya; Singh, Satyavir

    2016-07-01

    The existence of large amplitude potential structures will be investigated for a plasma composed of negative ions, positive ions, electrons and an additional fourth component of charged (usually positive) nano-sized ions in an attempt to model the plasma composition in the nighttime polar mesosphere (˜80 - 90 km altitude) [1]. The fourth ionic component becomes positively charged if there is a high enough concentration of negative ions which are sufficiently heavy. The positive charge on the fourth component can be explained by the capture of currents, and is not a result of photo-emission and secondary electron emission processes. Consequently, if the negative ions are much lighter, then the fourth ion component will become negatively charged. The charged ion species will be treated as inertial species which are cold or adiabatic, whilst the electrons will be considered to be Boltzmann-distributed (isothermal). Taking into consideration not only the dynamics of the heaviest species (dust-acoustic) but also the lighter ions (ion-acoustic), the theoretical study will use the Sagdeev pseudo-potential formalism to explore the existence of arbitrary amplitude solitons and double layer potential structures. [1] Observations of positively charged nanoparticles in the nighttime polar mesosphere, M. Rapp, J. Hedin, I. Strelnikova, M. Friederich, J. Gumbel, and F.˜J. Lübken, Geophys. Res. Letters. 32, L23821, doi:10.1029/2005GL024676 (2005).

  11. Scattering theory for arbitrary potentials

    SciTech Connect

    Kadyrov, A.S.; Bray, I.; Stelbovics, A.T.; Mukhamedzhanov, A.M.

    2005-09-15

    The fundamental quantities of potential scattering theory are generalized to accommodate long-range interactions. Definitions for the scattering amplitude and wave operators valid for arbitrary interactions including potentials with a Coulomb tail are presented. It is shown that for the Coulomb potential the generalized amplitude gives the physical on-shell amplitude without recourse to a renormalization procedure.

  12. The effect of free and trapped superthermal electrons on the propagation of compressive electron-and ion-acoustic solitary waves in electron-and ion-beam plasma

    NASA Astrophysics Data System (ADS)

    Kakad, Amar; Singh, Satyavir; Lakhina, Gurbax S.; Bharuthram, Ramesh

    Space plasmas are often observed to contain more particles in the high-energy tail than the usual Maxwellian distributions, and are well modeled by kappa distributions. In view of these observations, we study the existence of large amplitude electron-and ion-acoustic solitons in an unmagnetized multi-component plasma system consisting of free cold electrons, superthermal free and trapped hot electrons, and ions. The properties of these solitary waves are investi-gated by means of the pseudopotential approach. It is found that this model supports only compressive electron-and ion acoustic solitary waves and the amplitude of both the electron-and ion-mode decreases with the increase of Kappa index, k. The application of this model in interpreting the salient features of the broadband electrostatic noise in the different Earth's boundary layers will be discussed.

  13. Measurements of ion-ion collisional broadening of ion acoustic modes

    NASA Astrophysics Data System (ADS)

    Tierney, T. E.; Benage, J. F.; Montgomery, D. S.; Murillo, M. S.; Wysocki, F. J.; Rostoker, N.

    2002-10-01

    Although collisional plasmas are often encountered in inertial confinement fusion, dense plasma experiments and astrophysics, very few experiments have looked at the effects produced by the presence of these collisions. Ion-acoustic modes are predicted to broaden due to ion-ion collisions when the ion-ion mean free path, λ_ii, becomes comparable to the ion-acoustic wavelength, λ_iaw. This paper presents the first quantitative data of ion-acoustic wave broadening in moderately ion-ion collisional (0.05ion-acoustic modes was observed using collective Thomson scattering and analyzed using a collisional model that includes, ion and electron Landau, inhomogeneity and instrumental broadening. The results indicate that standard collisional models do not adequately predict the degree of ion-acoustic damping when 0.1

  14. Ion-acoustic and Buneman instabilities in collisional plasmas with q-nonextensive distribution

    NASA Astrophysics Data System (ADS)

    Hashemzadeh, M.

    2016-10-01

    The ion-acoustic and Buneman instabilities are studied in a current carrying plasma by taking into account the collisional effects and q-nonextensive distribution function. Using the kinetic theory and Bhatnagar-Gross-Krook collision model, a generalized dielectric permittivity function in the presence of moving electrons and electron and ion-neutral collision frequency is derived. The longitudinal dispersion relation in the Buneman and ion-acoustic instability limit is obtained. The results of the Buneman instability shows that the collision frequency, the q-parameter and electron drift velocity affect the growth rate of the instability. Finally, the profile of the ion-acoustic growth rate indicates that by increasing the ion to electron temperature ratio the instability growth rate decreases.

  15. Ion acoustic solitons in dense magnetized plasmas with nonrelativistic and ultrarelativistic degenerate electrons and positrons

    SciTech Connect

    Sadiq, Safeer; Mahmood, S.; Haque, Q.; Ali, Munazza Zulfiqar

    2014-09-20

    The propagation of electrostatic waves in a dense magnetized electron-positron-ion (EPI) plasma with nonrelativistic and ultrarelativistic degenerate electrons and positrons is investigated. The linear dispersion relation is obtained for slow and fast electrostatic waves in the EPI plasma. The limiting cases for ion acoustic wave (slow) and ion cyclotron wave (fast) are also discussed. Using the reductive perturbation method, two-dimensional propagation of ion acoustic solitons is found for both the nonrelativistic and ultrarelativistic degenerate electrons and positrons. The effects of positron concentration, magnetic field, and mass of ions on ion acoustic solitons are shown in numerical plots. The proper form of Fermi temperature for nonrelativistic and ultrarelativistic degenerate electrons and positrons is employed, which has not been used in earlier published work. The present investigation is useful for the understanding of linear and nonlinear electrostatic wave propagation in the dense magnetized EPI plasma of compact stars. For illustration purposes, we have applied our results to a pulsar magnetosphere.

  16. Ion-acoustic vortices in inhomogeneous and dissipative electron-positron-ion quantum magnetoplasmas

    NASA Astrophysics Data System (ADS)

    Masood, W.; Mirza, Arshad M.; Nargis, Shahida; Ayub, M.

    2009-04-01

    Linear and nonlinear properties of quantum ion-acoustic waves are studied in a nonuniform, dissipative quantum plasma (composed of electrons, positrons, and ions) with sheared ion flow parallel to the ambient magnetic field, using the quantum hydrodynamic model. It is shown that the shear ion flow parallel to the external magnetic field can drive the quantum ion-acoustic wave unstable provided ∣S∣ky>kz. Stationary solutions of the nonlinear equations that govern the quantum ion-acoustic waves are also obtained. It is found that electrostatic monopolar, dipolar, and vortex street-type solutions can appear in such a plasma. It is observed that the inclusion of positron, quantum statistical, and Bohm potential terms significantly modifies the scale lengths of these nonlinear structures. The relevance of the present investigation with regard to the dense astrophysical environments is also pointed out.

  17. Bifurcations of nonlinear ion-acoustic travelling waves in a multicomponent magnetoplasma with superthermal electrons

    NASA Astrophysics Data System (ADS)

    Selim, M. M.; El-Depsy, A.; El-Shamy, E. F.

    2015-12-01

    Properties of nonlinear ion-acoustic travelling waves propagating in a three-dimensional multicomponent magnetoplasma system composed of positive ions, negative ions and superthermal electrons are considered. Using the reductive perturbation technique (RPT), the Zkharov-Kuznetsov (ZK) equation is derived. The bifurcation theory of planar dynamical systems is applied to investigate the existence of the solitary wave solutions and the periodic travelling wave solutions of the resulting ZK equation. It is found that both compressive and rarefactive nonlinear ion-acoustic travelling waves strongly depend on the external magnetic field, the unperturbed positive-to-negative ions density ratio, the direction cosine of the wave propagation vector with the Cartesian coordinates, as well as the superthermal electron parameter. The present model may be useful for describing the formation of nonlinear ion-acoustic travelling wave in certain astrophysical scenarios, such as the D and F-regions of the Earth's ionosphere.

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

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

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

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

    SciTech Connect

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

    2013-04-15

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

  20. Ion acoustic solitons/double layers in two-ion plasma revisited

    SciTech Connect

    Lakhina, G. S. Singh, S. V. Kakad, A. P.

    2014-06-15

    Ion acoustic solitons and double layers are studied in a collisionless plasma consisting of cold heavier ion species, a warm lighter ion species, and hot electrons having Boltzmann distributions by Sagdeev pseudo-potential technique. In contrast to the previous results, no double layers and super-solitons are found when both the heavy and lighter ion species are treated as cold. Only the positive potential solitons are found in this case. When the thermal effects of the lighter ion species are included, in addition to the usual ion-acoustic solitons occurring at M > 1 (where the Mach number, M, is defined as the ratio of the speed of the solitary wave and the ion-acoustic speed considering temperature of hot electrons and mass of the heavier ion species), slow ion-acoustic solitons/double layers are found to occur at low Mach number (M < 1). The slow ion-acoustic mode is actually a new ion-ion hybrid acoustic mode which disappears when the normalized number density of lighter ion species tends to 1 (i.e., no heavier species). An interesting property of the new slow ion-acoustic mode is that at low number density of the lighter ion species, only negative potential solitons/double layers are found whereas for increasing densities there is a transition first to positive solitons/double layers, and then only positive solitons. The model can be easily applicable to the dusty plasmas having positively charged dust grains by replacing the heavier ion species by the dust mass and doing a simple normalization to take account of the dust charge.

  1. Head-on collision of dust-ion-acoustic soliton in quantum pair-ion plasma

    SciTech Connect

    Chatterjee, Prasanta; Ghorui, Malay kr.; Wong, C. S.

    2011-10-15

    In this paper, we study the head-on collision between two dust ion acoustic solitons in quantum pair-ion plasma. Using the extended Poincare-Lighthill-Kuo method, we obtain the Korteweg-de Vries equation, the phase shifts, and the trajectories after the head-on collision of the two dust ion acoustic solitons. It is observed that the phase shifts are significantly affected by the values of the quantum parameter H, the ratio of the multiples of the charge state and density of positive ions to that of the negative ions {beta} and the concentration of the negatively charged dust particles {delta}.

  2. Ion-acoustic double-layers in a magnetized plasma with nonthermal electrons

    SciTech Connect

    Rios, L. A.; Galvão, R. M. O.

    2013-11-15

    In the present work we investigate the existence of obliquely propagating ion-acoustic double layers in magnetized two-electron plasmas. The fluid model is used to describe the ion dynamics, and the hot electron population is modeled via a κ distribution function, which has been proved to be appropriate for modeling non-Maxwellian plasmas. A quasineutral condition is assumed to investigate these nonlinear structures, which leads to the formation of double-layers propagating with slow ion-acoustic velocity. The problem is investigated numerically, and the influence of parameters such as nonthermality is discussed.

  3. Quantum Ion-Acoustic Oscillations in Single-Walled Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Khan, S. A.; Iqbal, Z.; Wazir, Z.; Aman-ur-Rehman

    2016-05-01

    Quantum ion-acoustic oscillations in single-walled carbon nanotubes are studied by employing a quantum hydrodynamics model. The dispersion equation is obtained by Fourier transformation, which exhibits the existence of quantum ion-acoustic wave affected by change of density balance due to presence of positive or negative heavy species as stationary ion clusters and wave potential at equilibrium. The numerical results are presented, and the role of quantum degeneracy, nanotube geometry, electron exchange-correlation effects, and concentration and polarity of heavy species on wave dispersion is pointed out for typical systems of interest.

  4. Nonplanar Ion-Acoustic Solitons in Electron-Positron-Ion Quantum Plasmas

    NASA Astrophysics Data System (ADS)

    Khan A., S.; Mahmood, S.; Arshad, Mirza M.

    2009-04-01

    The propagation of nonplanar quantum ion-acoustic solitary waves in a dense, unmagnetized electron-positronion (e-p-i) plasma are studied by using the Korteweg-de Vries (KdV) model. The quantum hydrodynamic (QHD) equations are used taking into account the quantum diffraction and quantum statistics corrections. The analytical and numerical solutions of KdV equation reveal that the nonplanar ion-acoustic solitons are modified significantly with quantum corrections and positron concentration, and behave differently in different geometries.

  5. Head-on collision of dust-ion-acoustic soliton in quantum pair-ion plasma

    NASA Astrophysics Data System (ADS)

    Chatterjee, Prasanta; Ghorui, Malay kr.; Wong, C. S.

    2011-10-01

    In this paper, we study the head-on collision between two dust ion acoustic solitons in quantum pair-ion plasma. Using the extended Poincare-Lighthill-Kuo method, we obtain the Korteweg-de Vries equation, the phase shifts, and the trajectories after the head-on collision of the two dust ion acoustic solitons. It is observed that the phase shifts are significantly affected by the values of the quantum parameter H, the ratio of the multiples of the charge state and density of positive ions to that of the negative ions β and the concentration of the negatively charged dust particles δ.

  6. Tail formation by nonresonant interaction of ions with ion-acoustic turbulence

    NASA Astrophysics Data System (ADS)

    Appert, K.; Vaclavik, J.

    1981-09-01

    The quasilinear evolution of ion-acoustic turbulence induced by a constant current in a two-temperature plasma (with electron temperature much greater than ion temperature) is considered. The pertinent equations, which include both resonant and nonresonant wave-particle interactions, are discretized by a finite element method and solved numerically. If is shown first that the nonresonant interaction provides a powerful mechanism for ion tail formation. It is then shown that linear Landau damping on the high-energy ion tail so formed may quench the ion-acoustic instability as proposed by Dum et al. (1974) when interpreting their particle-in-cell simulation results.

  7. Effects of ionization and ion loss on dust ion-acoustic solitary waves in a collisional dusty plasma with suprathermal electrons

    NASA Astrophysics Data System (ADS)

    Mayout, Saliha; Gougam, Leila Ait; Tribeche, Mouloud

    2016-03-01

    The combined effects of ionization, ion loss, and electron suprathermality on dust ion-acoustic solitary waves in a collisional dusty plasma are examined. Carrying out a small but finite amplitude analysis, a damped Korteweg-de Vries (dK-dV) equation is derived. The damping term decreases with the increase of the spectral index and saturates for Maxwellian electrons. Choosing typical plasma parameters, the analytical approximate solution of the dK-dV equation is numerically analyzed. We first neglect the ionization and ion loss effects and account only for collisions to estimate the relative importance between these damping terms which can act concurrently. Interestingly, we found that as the suprathermal character of the electrons becomes important, the strength of the collisions related dissipation becomes more important and causes the dust ion-acoustic solitary wave amplitude to decay more rapidly. Moreover, the collisional damping may largely prevail over the ionization and ion loss related damping. The latter becomes more effective as the electrons evolve far away from their thermal equilibrium. Our results complement and provide new insights into previously published work on this problem.

  8. Effects of ionization and ion loss on dust ion- acoustic solitary waves in a collisional dusty plasma with suprathermal electrons

    NASA Astrophysics Data System (ADS)

    Tribeche, Mouloud; Mayout, Saliha

    2016-07-01

    The combined effects of ionization, ion loss and electron suprathermality on dust ion- acoustic solitary waves in a collisional dusty plasma are examined. Carrying out a small but finite amplitude analysis, a damped Korteweg- de Vries (dK-- dV) equation is derived. The damping term decreases with the increase of the spectral index and saturates for Maxwellian electrons. Choosing typical plasma parameters, the analytical approximate solution of the dK- dV equation is numerically analyzed. We first neglect the ionization and ion loss effects and account only for collisions to estimate the relative importance between these damping terms which can act concurrently. Interestingly, we found that as the suprathermal character of the electrons becomes important, the strength of the collisions related dissipation becomes more important and causes the DIA solitary wave amplitude to decay more rapidly. Moreover, the collisional damping may largely prevail over the ionization and ion loss related damping. The latter becomes more effective as the electrons evolve far away from their thermal equilibrium. Our results complement and provide new insights into previously published work on this problem.

  9. Solitonic, Periodic and Quasiperiodic Behaviors of Dust Ion Acoustic Waves in Superthermal Plasmas

    NASA Astrophysics Data System (ADS)

    Saha, Asit; Chatterjee, Prasanta

    2015-08-01

    The solitonic, periodic, and quasiperiodic behaviors of dust ion acoustic waves in superthermal plasmas with q-nonextensive electrons are studied using the bifurcation theory of planar dynamical systems through direct approach. Using a Galilean transformation, model equations are transformed to a Hamiltonian system involving electrostatic potential. The existence of solitary and periodic waves is shown for the unperturbed Hamiltonian system. Analytical forms of these waves are presented depending on physical parameters q and μ. The effects of q and μ are studied on characteristics of nonlinear dust ion acoustic solitary and periodic waves. It is observed that parameters q and μ significantly influence the characteristics of nonlinear dust ion acoustic solitary and periodic structures. Considering an external periodic perturbation, the quasiperiodic behavior of the perturbed Hamiltonian system for dust ion acoustic waves is studied. It is seen that the unperturbed Hamiltonian system has the solitary and periodic wave solutions whereas the perturbed Hamiltonian system has quasiperiodic motion for same values of parameters q, μ and v.

  10. Higher-order contributions to ion-acoustic solitary waves in a multicomponent plasma consisting of warm ions and two-component nonisothermal electrons

    SciTech Connect

    Das, K.P.; Majumdar, S.R.; Paul, S.N. ||

    1995-05-01

    An integrated form of the governing equations in terms of pseudopotential higher-order nonlinear and dispersive effects is obtained by applying the reductive perturbation method for ion-acoustic solitary waves in a collisionless unmagnetized multicomponent plasma having warm ions and two-component nonisothermal electrons. The present method is advantageous because instead of solving an inhomogeneous second-order differential equation at each order, as in the standard procedure, we solve a first-order inhomogeneous equation at each order except at the lowest. The expressions of both Mach number and width of the solitary wave are obtained as a function of the amplitude of the wave for third-order nonlinear and dispersive effects. The variations of potential, width, and Mach number against soliton amplitude are shown graphically, taking into consideration the nonisothermality of two-component electrons in the plasma.

  11. Effect of trapped electron on the dust ion acoustic waves in dusty plasma using time fractional modified Korteweg-de Vries equation

    SciTech Connect

    Nazari-Golshan, A.; Nourazar, S. S.

    2013-10-15

    The time fractional modified Korteweg-de Vries (TFMKdV) equation is solved to study the nonlinear propagation of small but finite amplitude dust ion-acoustic (DIA) solitary waves in un-magnetized dusty plasma with trapped electrons. The plasma is composed of a cold ion fluid, stationary dust grains, and hot electrons obeying a trapped electron distribution. The TFMKdV equation is derived by using the semi-inverse and Agrawal's methods and then solved by the Laplace Adomian decomposition method. Our results show that the amplitude of the DIA solitary waves increases with the increase of time fractional order β, the wave velocity v{sub 0}, and the population of the background free electrons λ. However, it is vice-versa for the deviation from isothermality parameter b, which is in agreement with the result obtained previously.

  12. Electrostatic shocks as nonlinear ion acoustic waves. [in auroral zones

    NASA Technical Reports Server (NTRS)

    Witt, E.; Hudson, M.

    1976-01-01

    A cold fluid approach is presented which yields exact double-layer solutions that can be used to model electrostatic S-type shocks. Solutions derived from the two-temperature electron model are presented in order to show the range of amplitudes and scale lengths possible for this plasma model and to examine how shock properties depend on orientation of the shock. The dependence of various double-layer quantities on plasma composition is then considered for the cold electron beam model. Double-layer solutions pertinent to describing electrostatic shocks are pointed out.

  13. Cylindrical and spherical dust-ion-acoustic modified Gardner solitons in dusty plasmas with two-temperature superthermal electrons

    SciTech Connect

    Alam, M. S.; Masud, M. M.; Mamun, A. A.

    2013-12-15

    A rigorous theoretical investigation has been performed on the propagation of cylindrical and spherical Gardner solitons (GSs) associated with dust-ion-acoustic (DIA) waves in a dusty plasma consisting of inertial ions, negatively charged immobile dust, and two populations of kappa distributed electrons having two distinct temperatures. The well-known reductive perturbation method has been used to derive the modified Gardner (mG) equation. The basic features (amplitude, width, polarity, etc.) of nonplanar DIA modified Gardner solitons (mGSs) have been thoroughly examined by the numerical analysis of the mG equation. It has been found that the characteristics of the nonplanar DIA mGSs significantly differ from those of planar ones. It has been also observed that kappa distributed electrons with two distinct temperatures significantly modify the basic properties of the DIA solitary waves and that the plasma system under consideration supports both compressive and rarefactive DIA mGSs. The present investigation should play an important role for understanding localized electrostatic disturbances in space and laboratory dusty plasmas where stationary negatively charged dust, inertial ions, and superthermal electrons with two distinct temperatures are omnipresent ingredients.

  14. Modulational instability and envelope excitation of ion-acoustic waves in quantum electron-positron-ion plasmas

    NASA Astrophysics Data System (ADS)

    Misra, A. P.; Bhowmik, C.; Shukla, P. K.

    2009-07-01

    The theoretical study of modulational instability (MI) and localized envelope excitations of finite amplitude ion-acoustic waves (IAWs) is revisited in an unmagnetized quantum electron-positron-ion plasma. For this purpose, a one-dimensional nonlinear Schrödinger equation, which governs the slow modulation of IAW packets, is derived by using the standard reductive perturbations technique. Two parameters, defining the ratio of the electron to ion number density (μ) and the quantum coupling parameter (H) describing the ratio of the "plasmonic energy density" to the Fermi energy density, are shown to play crucial roles in determining the modulational stability/MI domains, as well as for the existence of both bright and dark envelope solitons. It is found that the stability region increases (decreases) with increasing μ(H ), whereas the MI region for the IAW mode shifts to larger (smaller) wave number k as the value of μ(H ) increases. Moreover, the parameter H is shown to suppress the MI growth rate of the IAWs. The present results may be relevant to dense astrophysical plasmas (e.g., white dwarfs, where the electron-positron annihilation can be important, and where the particle density is of the order of 1034-1035 m-3) as well as to the next generation intense laser solid density plasma experiments.

  15. Measurements of thermal electron heating and the formation of a non-Maxwellian energy distribution due to ion acoustic turbulence

    SciTech Connect

    Hargreaves, T.A.

    1982-01-01

    The interaction of intense microwaves with an inhomogeneous plasma is studied in the U.C. Davis Prometheus III Device. P-polarized microwaves (f = 1.2 GHz, P/sub 0/ less than or equal to 5 KW) are incident on an essentially collisionless plasma with a long scale length in an oversized waveguide. For modest powers, large amplitude ion acoustic turbulence is observed on the underdense plasma shelf due to a combination of the parametric decay and the electron drift instabilities. Suprathermal and thermal electrons are strongly heated in this region with the thermal heating due to scattering with the ion turbulence. Since the cross section for interaction decreases rapidly as the electron energy increases, the low energy electrons are preferentially heated. The electron distribution function is measured and agrees with theory; the power absorption is reduced by up to a factor of two compared to a Maxwellian distribution. After the microwaves have been measured to decay, the electron distribution function is seen to relax back to its initial Maxwellian form. This occurs, as theory predicts, roughly on the electron-electron collision time scale.

  16. Particle-in-cell simulations of ion-acoustic waves with application to Saturn's magnetosphere

    SciTech Connect

    Koen, Etienne J.; Collier, Andrew B.; Hellberg, Manfred A.; Maharaj, Shimul K.

    2014-07-15

    Using a particle-in-cell simulation, the dispersion and growth rate of the ion-acoustic mode are investigated for a plasma containing two ion and two electron components. The electron velocities are modelled by a combination of two kappa distributions, as found in Saturn's magnetosphere. The ion components consist of adiabatic ions and an ultra-low density ion beam to drive a very weak instability, thereby ensuring observable waves. The ion-acoustic mode is explored for a range of parameter values such as κ, temperature ratio, and density ratio of the two electron components. The phase speed, frequency range, and growth rate of the mode are investigated. Simulations of double-kappa two-temperature plasmas typical of the three regions of Saturn's magnetosphere are also presented and analysed.

  17. The effect of boundaries on the ion acoustic beam-plasma instability in experiment and simulation

    SciTech Connect

    Rapson, Christopher; Grulke, Olaf; Matyash, Konstantin; Klinger, Thomas

    2014-05-15

    The ion acoustic beam-plasma instability is known to excite strong solitary waves near the Earth's bow shock. Using a double plasma experiment, tightly coupled with a 1-dimensional particle-in-cell simulation, the results presented here show that this instability is critically sensitive to the experimental conditions. Boundary effects, which do not have any counterpart in space or in most simulations, unavoidably excite parasitic instabilities. Potential fluctuations from these instabilities lead to an increase of the beam temperature which reduces the growth rate such that non-linear effects leading to solitary waves are less likely to be observed. Furthermore, the increased temperature modifies the range of beam velocities for which an ion acoustic beam plasma instability is observed.

  18. Excitation of Ion Acoustic Waves in Confined Plasmas with Untrapped Electrons

    NASA Astrophysics Data System (ADS)

    Schamis, Hanna; Dow, Ansel; Carlsson, Johan; Kaganovich, Igor; Khrabrov, Alexander

    2015-11-01

    Various plasma propulsion devices exhibit strong electron emission from the walls either as a result of secondary processes or due to thermionic emission. To understand the electron kinetics in plasmas with strong emission, we have performed simulations using a reduced model with the LSP particle-in-cell code. This model aims to show the instability generated by the electron emission, in the form of ion acoustic waves near the sheath. It also aims to show the instability produced by untrapped electrons that propagate across the plasma, similarly to a beam, and can drive ion acoustic waves in the plasma bulk. This work was made possible by funding from the Department of Energy for the Summer Undergraduate Laboratory Internship (SULI) program. This work is supported by the US DOE Contract No.DE-AC02-09CH11466.

  19. Ion acoustic kinetic Alfvén rogue waves in two temperature electrons superthermal plasmas

    NASA Astrophysics Data System (ADS)

    Kaur, Nimardeep; Saini, N. S.

    2016-10-01

    The propagation properties of ion acoustic kinetic Alfvén (IAKA) solitary and rogue waves have been investigated in two temperature electrons magnetized superthermal plasma in the presence of dust impurity. A nonlinear analysis is carried out to derive the Korteweg-de Vries (KdV) equation using the reductive perturbation method (RPM) describing the evolution of solitary waves. The effect of various plasma parameters on the characteristics of the IAKA solitary waves is studied. The dynamics of ion acoustic kinetic Alfvén rogue waves (IAKARWs) are also studied by transforming the KdV equation into nonlinear Schrödinger (NLS) equation. The characteristics of rogue wave profile under the influence of various plasma parameters (κc, μc, σ , θ) are examined numerically by using the data of Saturn's magnetosphere (Schippers et al. 2008; Sakai et al. 2013).

  20. Field theory for zero sound and ion acoustic wave in astrophysical matter

    NASA Astrophysics Data System (ADS)

    Gabadadze, Gregory; Rosen, Rachel A.

    2016-02-01

    We set up a field theory model to describe the longitudinal low-energy modes in high density matter present in white dwarf stars. At the relevant scales, ions—the nuclei of oxygen, carbon, and helium—are treated as heavy pointlike spin-0 charged particles in an effective field theory approach, while the electron dynamics is described by the Dirac Lagrangian at the one-loop level. We show that there always exists a longitudinal gapless mode in the system irrespective of whether the ions are in a plasma, crystal, or quantum liquid state. For certain values of the parameters, the gapless mode can be interpreted as a zero sound mode and, for other values, as an ion acoustic wave; we show that the zero sound and ion acoustic wave are complementary to each other. We discuss possible physical consequences of these modes for properties of white dwarfs.

  1. Generation of terahertz radiation via an electromagnetically induced transparency at ion acoustic frequency region in laser-produced dense plasmas.

    PubMed

    Nakagawa, Makoto; Kodama, Ryosuke; Higashiguchi, Takeshi; Yugami, Noboru

    2009-08-01

    Electromagnetically induced transparency is a well-known quantum phenomena that electromagnetic wave controls the refractive index of medium. It enables us to create a passband for low-frequency electromagnetic wave in a dense plasma even if the plasma is opaque for the electromagnetic wave. This technique can be used to prove the ion acoustic wave because the ion acoustic frequency is lower than the plasma frequency. We have investigated a feasibility of electromagnetic radiation at THz region corresponding to the ion acoustic frequency from a dense plasma. We confirmed that the passband is created at about 7.5 THz corresponding to the ion acoustic frequency in the electron plasma density of 10(21) cm(-3) with a Ti:Sapphire laser with the wavelength of 800 nm and the laser intensity of 10(17) W/cm(2). The estimated radiation power is around 1 MW, which is expected to be useful for nonlinear THz science and applications.

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

    NASA Astrophysics Data System (ADS)

    Abdelwahed, H. G.; El-Shewy, E. K.; Mahmoud, A. A.

    2016-06-01

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

  3. Excitation of ion-acoustic perturbations by incoherent kinetic Alfven waves in plasmas

    SciTech Connect

    Mendonca, J. T.; Shukla, P. K.

    2007-12-15

    The dispersion relation for ion-acoustic perturbations (IAPs) in the presence of incoherent kinetic Alfven waves (KAWs) in plasmas is derived. The wave-kinetic-approach is used to study the nonlinear interactions between an ensemble of random phase KAWs and IAPs. It is found that incoherent KAW spectrum is unstable against IAPs. The instability growth rates for particular cases are obtained. The present instability offers the possibility of heating ions in a turbulent magnetoplasma composed of incoherent KAWs.

  4. Excitation of ion-acoustic perturbations by incoherent kinetic Alfvén waves in plasmas

    NASA Astrophysics Data System (ADS)

    Mendonça, J. T.; Shukla, P. K.

    2007-12-01

    The dispersion relation for ion-acoustic perturbations (IAPs) in the presence of incoherent kinetic Alfvén waves (KAWs) in plasmas is derived. The wave-kinetic-approach is used to study the nonlinear interactions between an ensemble of random phase KAWs and IAPs. It is found that incoherent KAW spectrum is unstable against IAPs. The instability growth rates for particular cases are obtained. The present instability offers the possibility of heating ions in a turbulent magnetoplasma composed of incoherent KAWs.

  5. Solar wind implication on dust ion acoustic rogue waves

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

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

  6. Local Measurement of Electron Density and Temperature in High Temperature Laser Plasma Using the Ion-Acoustic Dispersion

    SciTech Connect

    Froula, D H; Davis, P; Ross, S; Meezan, N; Divol, L; Price, D; Glenzer, S H; Rousseaux, C

    2005-09-20

    The dispersion of ion-acoustic fluctuations has been measured using a novel technique that employs multiple color Thomson-scattering diagnostics to measure the frequency spectrum for two separate thermal ion-acoustic fluctuations with significantly different wave vectors. The plasma fluctuations are shown to become dispersive with increasing electron temperature. We demonstrate that this technique allows a time resolved local measurement of electron density and temperature in inertial confinement fusion plasmas.

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

    SciTech Connect

    Zhang Jiefang; Wang Yueyue; Wu Lei

    2009-06-15

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

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

    NASA Astrophysics Data System (ADS)

    Ur-Rehman, Hafeez; Mahmood, S.

    2016-09-01

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

  9. Ion Acoustic Wave Broadening Observations in Moderately Coupled, Moderately Collisional Plasmas

    NASA Astrophysics Data System (ADS)

    Tierney, T. E.; Benage, J. F.; Montgomery, D. S.; Murillo, M. S.; Wysocki, F. J.; Johnson, R. P.

    2002-11-01

    Weakly coupled scattering theory breaks down as the ratio of Coulomb interaction energy to thermal kinetic energy, Γ _ii =(Ze)^2/a _iikT, approaches unity and/or as collisions become more frequent. Accurate modeling is required in order to fit collective Thomson scattering features from ion acoustic waves and determine plasma parameters Z, Te and Ti. The Trident Laser was used to produce Al, CH, CH2 laser-plasmas, where ne ˜ 10^20 cm-3, T_e ˜ 75-150 eV, Γ _ii ˜ 0.1-0.75 and N _D ˜ 100-500. A separate 351-nm beam was used as a low intensity probe for Thomson scattering. The scattered light was recorded by an imaging spectrograph to provide temporally and spatially -resolved spectral profiles of thermal ion acoustic waves and Langmuir waves. Ion acoustic waves are observed to be broadened to near the frequency shift, dω _ia/ω _ia ˜ 0.75-1.25. Using a collisionless model, we show that plasma inhomogeneities and instruments produce only ˜50% of the broadening. We conclude that collisions and/or coupling cannot be ignored in modeling of collective modes in warm dense plasmas.

  10. Argon–oxygen dc magnetron discharge plasma probed with ion acoustic waves

    SciTech Connect

    Saikia, Partha Saikia, Bipul Kumar; Goswami, Kalyan Sindhu; Phukan, Arindam

    2014-05-15

    The precise determination of the relative concentration of negative ions is very important for the optimization of magnetron sputtering processes, especially for those undertaken in a multicomponent background produced by adding electronegative gases, such as oxygen, to the discharge. The temporal behavior of an ion acoustic wave excited from a stainless steel grid inside the plasma chamber is used to determine the relative negative ion concentration in the magnetron discharge plasma. The phase velocity of the ion acoustic wave in the presence of negative ions is found to be faster than in a pure argon plasma, and the phase velocity increases with the oxygen partial pressure. Optical emission spectroscopy further confirms the increase in the oxygen negative ion density, along with a decrease in the argon positive ion density under the same discharge conditions. The relative negative ion concentration values measured by ion acoustic waves are compared with those measured by a single Langmuir probe, and a similarity in the results obtained by both techniques is observed.

  11. A Korteweg-de Vries Burgers-like equation for weakly nonlinear dust ion-acoustic waves in a charge-varying dusty plasma with nonthermal electrons

    SciTech Connect

    Berbri, Abderrezak; Tribeche, Mouloud

    2009-05-15

    A weakly nonlinear analysis is carried out to derive a Korteweg-de Vries Burgers-like equation for small but finite amplitude dust ion-acoustic (DIA) waves in a charge varying dusty plasma with non thermally distributed electrons. The correct expression for the nonthermal electron charging current is used. Interestingly, it may be noted that due to electron nonthermality and finite equilibrium ion streaming velocity, the present dusty plasma model can admit compressive as well as rarefactive DIA solitary waves. Furthermore, there may exist DIA shocks which have either monotonic or oscillatory behavior and the properties of which depend sensitively on the number of fast nonthermal electrons. Our results should be useful to understand the properties of localized DIA waves that may occur in space dusty plasmas.

  12. Alternative dust-ion acoustic waves in a magnetized charge varying dusty plasma with nonthermal electrons having a vortex-like velocity distribution

    NASA Astrophysics Data System (ADS)

    Hadjaz, Idir; Tribeche, Mouloud

    2014-06-01

    Alternative localized dust-ion acoustic waves are investigated in a magnetized charge varying dusty plasma with nonthermal electrons having a vortex-like velocity distribution. The correct non-Maxwellian charging currents are obtained based on the well-known orbit limited motion theory. Following the standard reductive perturbation technique, a Schamel-Zakharov Kuznetsov Burgers (S-ZKB) equation is derived. It is shown that due to an interplay between trapping and nonthermality, our dusty plasma model may support solitary as well as shock waves the main quantities (phase velocity, amplitude and width) of which are drastically influenced by trapping, nonthermality and charge variation. Due to the flexibility provided by the outlined distribution function (two concepts of non isothermality), we stress that our model should provide a good fit of the space observations.

  13. Obliquely propagating ion-acoustic solitons and supersolitons in four-component auroral plasmas

    NASA Astrophysics Data System (ADS)

    Rufai, O. R.; Bharuthram, R.; Singh, S. V.; Lakhina, G. S.

    2016-02-01

    Arbitrary amplitude nonlinear low frequency electrostatic soliton and supersoliton structures are studied in magnetized four-component auroral plasmas composed of a cold singly charged oxygen-ion fluid, Boltzmann distribution of hot protons and two distinct group of electron species. Using the Sagdeev pseudo-potential technique, the characteristics of obliquely propagating nonlinear structures are investigated analytically and numerically. The model supports the evolution of soliton and supersoliton structures in the auroral acceleration region. Depending on the parametric region, the positive and negative potential solitons coexists at lower Mach numbers, but at higher Mach numbers only negative potential solitons and supersolitons can exist. The presence of hot protons restricted the Mach number of the nonlinear structures to exist only at the subsonic region. The present investigation concurs with the Swedish Viking satellite observations in the auroral region.

  14. Interaction of dust-ion acoustic solitary waves in nonplanar geometry with electrons featuring Tsallis distribution

    SciTech Connect

    Narayan Ghosh, Uday; Chatterjee, Prasanta; Tribeche, Mouloud

    2012-11-15

    The head-on collisions between nonplanar dust-ion acoustic solitary waves are dealt with by an extended version of Poincare-Lighthill-Kuo perturbation method, for a plasma having stationary dust grains, inertial ions, and nonextensive electrons. The nonplanar geometry modified analytical phase-shift after a head-on collision is derived. It is found that as the nonextensive character of the electrons becomes important, the phase-shift decreases monotonically before levelling-off at a constant value. This leads us to think that nonextensivity may have a stabilizing effect on the phase-shift.

  15. An analytical and numerical investigation of ion acoustic waves in a two-ion plasma

    SciTech Connect

    Vu, H.X.; Wallace, J.M.; Bezzerides, B. )

    1994-11-01

    The ion acoustic dispersion relation for a plasma containing two distinct ion species is investigated over a wide range of plasma conditions. An approximate general analytic solution to the dispersion relation has been found, and is shown, by comparison to accurate numerical solutions of the individual modes, to be remarkably precise. This solution provides for the first time a systematic account of the totality of ion acoustic modes of the two-ion system. It has been found that ion acoustic modes consist of two types of modes: (a) at least one, and, at most, two weakly damped modes for which [vert bar][omega][sub I]/[omega][sub R][vert bar][much lt]1, and (b) an infinity of critically damped modes for which [omega][sub I]/[omega][sub R][congruent][minus]1. The critically damped modes are organized into two distinct categories: (a) modes for which [vert bar][omega][vert bar]/[sub K][gt][sub V][sub F] ([sub V][sub F] is the thermal speed of the fast ion species); and (b) modes for which [sub V][sub S][lt][vert bar][omega][vert bar]/[sub K][lt][sub V][sub F] ([sub V][sub S] is the thermal speed of the slow ion species). The critically damped modes with [vert bar][omega][vert bar]/[sub K][gt][sub V][sub F] are further organized into three distinct classes: (1) modes with phase speeds characterized by [sub V][sub F], (2) modes with phase speeds characterized by [sub V][sub F][sub S]/[radical][sub V] [sup 2][sub F][minus][sub V][sup 2][sub S], and (3) modes with phase speeds characterized by [sub V][sub S]. The critically damped modes with [sub V][sub S][lt][vert bar][omega][vert bar]/[sub K][lt][sub V][sub F] belong to a single class, and are characterized by [sub V][sub S]. Generally, it is found that there are one, or, at most, two modes with relatively small damping, while most of the remaining modes are too strongly damped to be physically realized. It has also been found possible to maximize ion acoustic damping by a wise choice of relative ion concentrations.

  16. Two different types of enhanced ion acoustic fluctuations observed in the upper ionosphere

    SciTech Connect

    Forme, F.R.E.; Fontaine, D.; Wahlund, J.E.

    1995-08-01

    UHF and VHF data for the EISCAT incoherent scatter radar facility in northern Scandinavia is presented. Electron and ion temperatures, electron density, and ion drift velocity were measured from heights of 280 to 1500 km. Enhanced ion acoustic fluctuations are more observable with VHF than UHF radar due to wavelength effects. The fluctuations are usually associated with a large flux of precipitating electrons with energies from 100 ev to 10 kev. The spatial extent of the turbulent regions are determined. 23 refs., 6 figs.

  17. Decay of electrostatic hydrogen cyclotron waves into ion acoustic modes in auroral field lines

    NASA Astrophysics Data System (ADS)

    Bergmann, R.; Hudson, M. K.

    1987-03-01

    The coherent three-wave decay of a linearly unstable electrostatic hydrogen cyclotron (EHC) wave into stable EHC and ion acoustic modes is considered. The general problem of the three weakly interacting electrostatic normal modes in a Maxwellian plasma is discussed. EHC is examined in a fluid description, and the results are used to guide a similar study in a Vlasov plasma system intended to model the aurora acceleration region parameters. The time dependence of the decay in a simple three-wave interaction is presented in order to show how wave saturation can arise.

  18. Decay of electrostatic hydrogen cyclotron waves into ion acoustic modes in auroral field lines

    NASA Technical Reports Server (NTRS)

    Bergmann, R.; Hudson, M. K.

    1987-01-01

    The coherent three-wave decay of a linearly unstable electrostatic hydrogen cyclotron (EHC) wave into stable EHC and ion acoustic modes is considered. The general problem of the three weakly interacting electrostatic normal modes in a Maxwellian plasma is discussed. EHC is examined in a fluid description, and the results are used to guide a similar study in a Vlasov plasma system intended to model the aurora acceleration region parameters. The time dependence of the decay in a simple three-wave interaction is presented in order to show how wave saturation can arise.

  19. Properties of solitary ion acoustic waves in a quantized degenerate magnetoplasma with trapped electrons

    SciTech Connect

    Tsintsadze, N. L.; Tagviashvili, M. N.; Shah, H. A.; Qureshi, M. N. S.

    2015-02-15

    We have undertaken the investigation of ion acoustic solitary waves in both weakly and strongly quantized degenerate magnetoplasmas. It is seen that a singular point clearly demarcates the regions of weak and strong quantization due to the ambient magnetic field. The effect of the magnetic field is taken into account via the parameter  η{sub 0}=ℏω{sub ce}/ε{sub Fe} and the Mach number, and their effect on the formation of solitary structures is investigated in both cases and some results are presented graphically.

  20. Stability analysis for two-dimensional ion-acoustic waves in quantum plasmas

    SciTech Connect

    Seadawy, A. R.

    2014-05-15

    The quantum hydrodynamic model is applied to two-dimensional ion-acoustic waves in quantum plasmas. The two-dimensional quantum hydrodynamic model is used to obtain a deformed Kortewegde Vries (dKdV) equation by reductive perturbation method. By using the solution of auxiliary ordinary equations, a extended direct algebraic method is described to construct the exact solutions for nonlinear quantum dKdV equation. The present results are describing the generation and evolution of such waves, their interactions, and their stability.

  1. Nonlinear ion acoustic dissipative shock structure with exchange-correlation effects in quantum semiconductor plasmas

    NASA Astrophysics Data System (ADS)

    Hussain, S.; Akhtar, N.

    2016-09-01

    Ion acoustic shocks in the electron-hole-ion semiconductor plasmas have been studied. The quantum recoil effects, exchange-correlation effects and degenerate pressure of electrons and holes are included. The ion species are considered classical and their dissipation is taken into account via the dynamic viscosity. The Korteweg de Vries Burgers equation is derived by using reductive perturbation approach. The excitation of shock waves in different semiconductor plasmas is pointed out. For numerical analyses, the plasma parameters of different semiconductors are considered. The impact of variation of the plasma parameters on the strength of the shock wave in the semiconductor plasmas is discussed.

  2. Weakly nonlinear dust ion-acoustic shock waves in a dusty plasma with nonthermal electrons

    SciTech Connect

    Berbri, Abderrezak; Tribeche, Mouloud

    2009-05-15

    Weakly nonlinear dust ion-acoustic (DIA) shock waves are investigated in a dusty plasma with nonthermal electrons. A modified Korteweg-de Vries equation with a cubic nonlinearity is derived. Due to the net negative dust charge {mu}Z{sub d} and electron nonthermality, the present plasma model can admit compressive and rarefactive weak DIA shock waves. The effect of increasing {mu}Z{sub d} is to lower the critical nonthermal parameter {beta}{sub c} above which only rarefactive DIA shock waves are admitted. Our investigation may help to understand the nonlinear structures observed in the auroral acceleration regions.

  3. Measurement of the flow velocity in unmagnetized plasmas by counter propagating ion-acoustic waves

    SciTech Connect

    Ma, J.X.; Li Yangfang; Xiao Delong; Li Jingju; Li Yiren

    2005-06-15

    The diffusion velocity of an inhomogeneous unmagnetized plasma is measured by means of the phase velocities of ion-acoustic waves propagating along and against the direction of the plasma flow. Combined with the measurement of the plasma density distributions by usual Langmuir probes, the method is applied to measure the ambipolar diffusion coefficient and effective ion collision frequency in inhomogeneous plasmas formed in an asymmetrically discharged double-plasma device. Experimental results show that the measured flow velocities, diffusion coefficients, and effective collision frequencies are in agreement with ion-neutral collision dominated diffusion theory.

  4. On the Hamiltonian structure of ion-acoustic plasma waves and water waves in channels

    NASA Astrophysics Data System (ADS)

    Menyuk, C. R.; Chen, H.-H.

    1986-04-01

    It is shown that the Hamiltonian structure of ion-acoustic waves and channel waves may be used to derive the Hamiltonian structure of the Korteweg-de Vries equation and its higher-order corrections. The Hamiltonian approach used here is more systematic and less laborious than standard methods for deriving the Korteweg-de Vries equation. It is also more revealing. In particular, it is shown that the Poisson bracket of the corrected equations equals the Korteweg-de Vries Poisson bracket at every order. It is also shown that the corrected equations become nonlocal at sufficiently high order.

  5. Ion-acoustic solitons, double layers and supersolitons in a plasma with two ion- and two electron species

    SciTech Connect

    Olivier, C. P. Maharaj, S. K.; Bharuthram, R.

    2015-08-15

    The polarity of ion-acoustic solitons that arise in a plasma with two (same mass, different temperature) ion species and two (different temperature) electron species is investigated. Two different fluid models are compared. The first model treats all species as adiabatic fluids, while the second model treats the ion species as adiabatic, and the electron species as isothermal. Nonlinear structures are analysed via the reductive perturbation analysis and pseudo-potential analysis. Each model supports both slow and fast ion-acoustic solitons, associated with the two (slow and fast) ion-acoustic speeds. The models support both positive and negative polarity solitons associated with the slow ion-acoustic speed. Moreover, results are in good agreement, and both models support positive and negative polarity double layers. For the fast ion-acoustic speed, the first model supports only positive polarity solitons, while the second model supports solitons of both polarity, coexistence of positive and negative polarity solitons, double layers and supersolitons. A novel feature of our analysis is the evaluation of nonlinear structures at critical number densities where polarity changes occur. This analysis shows that solitons that occur at the acoustic speed are neither a necessary nor a sufficient condition for the phenomenon of coexistence. The relationship between the existence regions of supersolitons and soliton polarity is also discussed.

  6. Oblique propagation of dust ion-acoustic solitary waves in a magnetized dusty pair-ion plasma

    SciTech Connect

    Misra, A. P. E-mail: apmisra@gmail.com; Barman, Arnab

    2014-07-15

    We investigate the propagation characteristics of electrostatic waves in a magnetized pair-ion plasma with immobile charged dusts. It is shown that obliquely propagating (OP) low-frequency (in comparison with the negative-ion cyclotron frequency) long-wavelength “slow” and “fast” modes can propagate, respectively, as dust ion-acoustic (DIA) and dust ion-cyclotron (DIC)-like waves. The properties of these modes are studied with the effects of obliqueness of propagation (θ), the static magnetic field, the ratios of the negative to positive ion masses (m), and temperatures (T) as well as the dust to negative-ion number density ratio (δ). Using the standard reductive perturbation technique, we derive a Korteweg-de Vries (KdV) equation which governs the evolution of small-amplitude OP DIA waves. It is found that the KdV equation admits only rarefactive solitons in plasmas with m well below its critical value m{sub c} (≫ 1) which typically depends on T and δ. It is shown that the nonlinear coefficient of the KdV equation vanishes at m = m{sub c}, i.e., for plasmas with much heavier negative ions, and the evolution of the DIA waves is then described by a modified KdV (mKdV) equation. The latter is shown to have only compressive soliton solution. The properties of both the KdV and mKdV solitons are studied with the system parameters as above, and possible applications of our results to laboratory and space plasmas are briefly discussed.

  7. Oblique propagation of ion acoustic soliton-cnoidal waves in a magnetized electron-positron-ion plasma with superthermal electrons

    SciTech Connect

    Wang, Jian-Yong; Cheng, Xue-Ping; Tang, Xiao-Yan; Yang, Jian-Rong; Ren, Bo

    2014-03-15

    The oblique propagation of ion-acoustic soliton-cnoidal waves in a magnetized electron-positron-ion plasma with superthermal electrons is studied. Linear dispersion relations of the fast and slow ion-acoustic modes are discussed under the weak and strong magnetic field situations. By means of the reductive perturbation approach, Korteweg-de Vries equations governing ion-acoustic waves of fast and slow modes are derived, respectively. Explicit interacting soliton-cnoidal wave solutions are obtained by the generalized truncated Painlevé expansion. It is found that every peak of a cnoidal wave elastically interacts with a usual soliton except for some phase shifts. The influence of the electron superthermality, positron concentration, and magnetic field obliqueness on the soliton-cnoidal wave are investigated in detail.

  8. Coupling of electrostatic ion cyclotron and ion acoustic waves in the solar wind

    NASA Astrophysics Data System (ADS)

    Sreeraj, T.; Singh, S. V.; Lakhina, G. S.

    2016-08-01

    The coupling of electrostatic ion cyclotron and ion acoustic waves is examined in three component magnetized plasma consisting of electrons, protons, and alpha particles. In the theoretical model relevant to solar wind plasma, electrons are assumed to be superthermal with kappa distribution and protons as well as alpha particles follow the fluid dynamical equations. A general linear dispersion relation is derived for such a plasma system which is analyzed both analytically and numerically. For parallel propagation, electrostatic ion cyclotron (proton and helium cyclotron) and ion acoustic (slow and fast) modes are decoupled. For oblique propagation, coupling between the cyclotron and acoustic modes occurs. Furthermore, when the angle of propagation is increased, the separation between acoustic and cyclotron modes increases which is an indication of weaker coupling at large angle of propagation. For perpendicular propagation, only cyclotron modes are observed. The effect of various parameters such as number density and temperature of alpha particles and superthermality on dispersion characteristics is examined in details. The coupling between various modes occurs for small values of wavenumber.

  9. Drift ion acoustic shock waves in an inhomogeneous two-dimensional quantum magnetoplasma

    NASA Astrophysics Data System (ADS)

    Masood, W.; Karim, S.; Shah, H. A.; Siddiq, M.

    2009-04-01

    Linear and nonlinear propagation characteristics of drift ion acoustic waves are investigated in an inhomogeneous quantum plasma with neutrals in the background employing the quantum hydrodynamics (QHD) model. In this regard, a quantum Kadomtsev-Petviashvili-Burgers (KPB) equation is derived for the first time. It is shown that the ion acoustic wave couples with the drift wave if the parallel motion of ions is taken into account. Discrepancies in the earlier works on drift solitons and shocks in inhomogeneous plasmas are also pointed out and a correct theoretical framework is presented to study the one-dimensional as well as the two-dimensional propagation of shock waves in an inhomogeneous quantum plasma. Furthermore, the solution of KPB equation is presented using the tangent hyperbolic (tanh) method. The variation of the shock profile with the quantum Bohm potential, collision frequency, and ratio of drift to shock velocity in the comoving frame, v∗/u, are also investigated. It is found that increasing the number density and collision frequency enhances the strength of the shock. It is also shown that the fast drift shock (i.e., v∗/u>0) increases, whereas the slow drift shock (i.e., v∗/u<0) decreases the strength of the shock. The relevance of the present investigation with regard to dense astrophysical environments is also pointed out.

  10. Response to 'Comment on 'Nonlinear properties of small amplitude dust ion acoustic solitary waves'' [Phys. Plasmas 15, 104703 (2008)

    SciTech Connect

    Gupta, M. R.; Sarkar, S.; Khan, Manoranjan; Ghosh, Samiran

    2008-10-15

    The objections are not justified. It should have been noted that ion charge number z{sub i}=1 throughout the referred paper [Ghosh et al., Phys. Plasmas 7, 3594 (2000)]. There is no inconsistency in the formulation of the referred paper as explained in the text.

  11. The effect of q-distributed electrons on the head-on collision of ion acoustic solitary waves

    SciTech Connect

    Ghosh, Uday Narayan; Chatterjee, Prasanta; Roychoudhury, Rajkumar

    2012-01-15

    The head-on collision of ion acoustic solitary waves (IASWs) in two component plasma comprising nonextensive distributed electrons is investigated. Two opposite directional Kortewg-de-vries (KdV) equations are derived and the phase shift due to collision is obtained using the extended version of Poincare-Lighthill-Kuo method. Different ranges of nonextensive parameter q are considered and their effects on phase shifts are observed. It is found that the presence of nonextensive distributed electrons plays a significant role on the nature of collision of ion acoustic solitary waves.

  12. Fluid nonlinear frequency shift of nonlinear ion acoustic waves in multi-ion species plasmas in the small wave number region.

    PubMed

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

    2016-08-01

    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. Pictures of the nonlinear frequency shift from harmonic generation and particle 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 with the theoretical result of multi-ion species plasmas. When the wave number kλ_{De} is small, such as kλ_{De}=0.1, the fluid NFS dominates in the total NFS and will reach as large as nearly 15% when the wave amplitude |eϕ/T_{e}|∼0.1, which indicates that in the condition of small kλ_{De}, the fluid NFS dominates in the saturation of stimulated Brillouin scattering, especially when the nonlinear IAW amplitude is large. PMID:27627405

  13. Head-on collisions of ion-acoustic Korteweg-de Vries/modified Korteweg-de Vries solitons in a magnetized quantum electron-positron-ion plasma

    NASA Astrophysics Data System (ADS)

    Ghorui, Malay Kumar; Samanta, Utpal Kumar; Chatterjee, Prasanta

    2013-06-01

    The head-on collisions of ion-acoustic solitary waves (IASWs) in a dense magnetized quantum plasma are investigated. The two-sided Korteweg-de Vries (KdV) equations in generic case as well as the two-sided modified Korteweg-de Vries (mKdV) equations in a special case are obtained, the analytical phase shifts and the trajectories after the head-on collisions of two IASWs in a three species quantum plasma are derived by using the extended version of Poincaré-Lighthill-Kuo (PLK) method for both the situations. We provide the theoretical predictions about the existence of compressive and rarefactive IASWs in the model. We observe that in generic case collisions are possible among the same polarity solitons, whereas in the special case collisions are possible among the same or opposite polarities solitons. Moreover the colliding phase shifts are significantly affected by the quantum diffraction parameter, by the square of the ratio of ion gyrofrequency to ion plasma frequency and by obliqueness of propagation. The important observations of this manuscript are that the waves reach a maximum amplitude which is the superposition of the initial amplitudes and they suffer a time delay during their collision. The plasma parameter values for white dwarfs are taken for discussion.

  14. Fluid nonlinear frequency shift of nonlinear ion acoustic waves in multi-ion species plasmas in the small wave number region

    NASA Astrophysics Data System (ADS)

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

    2016-08-01

    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. Pictures of the nonlinear frequency shift from harmonic generation and particle 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 with the theoretical result of multi-ion species plasmas. When the wave number k λD e is small, such as k λD e=0.1 , the fluid NFS dominates in the total NFS and will reach as large as nearly 15 % when the wave amplitude |e ϕ / Te|˜0.1 , which indicates that in the condition of small k λD e , the fluid NFS dominates in the saturation of stimulated Brillouin scattering, especially when the nonlinear IAW amplitude is large.

  15. Stimulated scattering of a whistler wave off ion-cyclotron and ion-acoustic modes in a dusty plasma

    SciTech Connect

    Annou, R.; Tripathi, V.K.

    1998-01-01

    A whistler wave propagating through a magnetized dusty plasma undergoes stimulated Brillioun scattering off ion-cyclotron and ion-acoustic modes. The dust has little effect on nonlinear coupling. However, it reduces the growth rate by introducing linear damping on the low-frequency modes. {copyright} {ital 1998 American Institute of Physics.}

  16. Characterization of Ion-Acoustic Wave Reflection Off A Plasma Chamber Wall

    NASA Astrophysics Data System (ADS)

    Berumen, Jorge; Chu, Feng; Hood, Ryan; Mattingly, Sean; Rogers, Anthony; Skiff, Fred

    2015-11-01

    We present an experimental characterization of the ion acoustic wave reflection coefficient off a plasma chamber wall. The experiment is performed in a cylindrical, magnetized, singly-ionized Argon inductively-coupled gas discharge plasma that is weakly collisional with typical conditions: n ~ 1010cm-3 Te ~ 3 eV and B ~ 1 kG. The main diagnostics are laser-induced fluorescence and Langmuir probe measurements. A survey of the ion velocity distribution function's zeroth and first order as well as density fluctuations at different wave excitation frequencies is obtained. Analysis of the reflection coefficient's dependence on the phase velocity and frequency of the wave is done through the characterization of waves utilizing Case-Van Kampen modes and the use of Morrison's G-transform. This research is supported by the Department of Energy under grant No. DOE DE-FG02-99ER54543.

  17. Hybrid (Vlasov-Fluid) simulation of ion-acoustic solitons chain formation including trapped electrons

    SciTech Connect

    Behjat, E.; Aminmansoor, F.; Abbasi, H.

    2015-08-15

    Disintegration of a Gaussian profile into ion-acoustic solitons in the presence of trapped electrons [H. Hakimi Pajouh and H. Abbasi, Phys. Plasmas 15, 082105 (2008)] is revisited. Through a hybrid (Vlasov-Fluid) model, the restrictions associated with the simple modified Korteweg de-Vries (mKdV) model are studied. For instance, the lack of vital information in the phase space associated with the evolution of electron velocity distribution, the perturbative nature of mKdV model which limits it to the weak nonlinear cases, and the special spatio-temporal scaling based on which the mKdV is derived. Remarkable differences between the results of the two models lead us to conclude that the mKdV model can only monitor the general aspects of the dynamics, and the precise picture including the correct spatio-temporal scales and the properties of solitons should be studied within the framework of hybrid model.

  18. Weakly nonlinear ion-acoustic excitations in a relativistic model for dense quantum plasma.

    PubMed

    Behery, E E; Haas, F; Kourakis, I

    2016-02-01

    The dynamics of linear and nonlinear ionic-scale electrostatic excitations propagating in a magnetized relativistic quantum plasma is studied. A quantum-hydrodynamic model is adopted and degenerate statistics for the electrons is taken into account. The dispersion properties of linear ion acoustic waves are examined in detail. A modified characteristic charge screening length and "sound speed" are introduced, for relativistic quantum plasmas. By employing the reductive perturbation technique, a Zakharov-Kuznetzov-type equation is derived. Using the small-k expansion method, the stability profile of weakly nonlinear slightly supersonic electrostatic pulses is also discussed. The effect of electron degeneracy on the basic characteristics of electrostatic excitations is investigated. The entire analysis is valid in a three-dimensional as well as in two-dimensional geometry. A brief discussion of possible applications in laboratory and space plasmas is included. PMID:26986431

  19. Nonlinear ion-acoustic double-layers in electronegative plasmas with electrons featuring Tsallis distribution

    NASA Astrophysics Data System (ADS)

    Ghebache, Siham; Tribeche, Mouloud

    2016-04-01

    Weakly nonlinear ion-acoustic (IA) double-layers (DLs), which accompany electronegative plasmas composed of positive ions, negative ions, and nonextensive electrons are investigated. A generalized Korteweg-de Vries equation with a cubic nonlinearity is derived using a reductive perturbation method. Different types of electronegative plasmas inspired from the experimental studies of Ichiki et al. (2001) are discussed. It is shown that the IA wave phase velocity, in different mixtures of negative and positive ions, decreases as the nonextensive parameter q increases, before levelling-off at a constant value for larger q. Moreover, a relative increase of Q involves an enhancement of the IA phase velocity. Existence domains of either solitary waves or double-layers are then presented and their parametric dependence is determined. Owing to the electron nonextensivity, our present plasma model can admit compressive as well as rarefactive IA-DLs.

  20. Nonlinear ion-acoustic waves in a degenerate plasma with nuclei of heavy elements

    NASA Astrophysics Data System (ADS)

    Hossen, M. A.; Mamun, A. A.

    2015-10-01

    The ion-acoustic (IA) solitary waves propagating in a fully relativistic degenerate dense plasma (containing relativistic degenerate electron and ion fluids, and immobile nuclei of heavy elements) have been theoretically investigated. The relativistic hydrodynamic model is used to derive the Korteweg-de Vries (K-dV) equation by the reductive perturbation method. The stationary solitary wave solution of this K-dV equation is obtained to characterize the basic features of the IA solitary structures that are found to exist in such a degenerate plasma. It is found that the effects of electron dynamics, relativistic degeneracy of the plasma fluids, stationary nuclei of heavy elements, etc., significantly modify the basic properties of the IA solitary structures. The implications of this results in astrophysical compact objects like white dwarfs are briefly discussed.

  1. Heavy-Ion-Acoustic Solitary and Shock Waves in an Adiabatic Multi-Ion Plasma

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

    The standard reductive perturbation method has been employed to derive the Korteweg-deVries (K-dV) and Burgers (BG) equations to investigate the basic properties of heavy-ion-acoustic (HIA) waves in a plasma system which is supposed to be composed of nonthermal electrons, Boltzmann distributed light ions, and adiabatic positively charged inertial heavy ions. The HIA solitary and shock structures are found to exist with either positive or negative potential. It is found that the effects of adiabaticity of inertial heavy ions, nonthermality of electrons, and number densities of plasma components significantly modify the basic properties of the HIA solitary and shock waves. The implications of our results may be helpful in understanding the electrostatic perturbations in various laboratory and astrophysical plasma environments.

  2. Linear and nonlinear ion-acoustic waves in an unmagnetized electron-positron-ion quantum plasma

    NASA Astrophysics Data System (ADS)

    Ali, S.; Moslem, W. M.; Shukla, P. K.; Schlickeiser, R.

    2007-08-01

    The linear and nonlinear properties of the ion-acoustic waves (IAWs) are investigated by using the quantum hydrodynamic equations together with the Poisson equation in a three-component quantum electron-positron-ion plasma. For this purpose, a linear dispersion relation, a Korteweg-de Vries equation and an energy equation containing quantum corrections are derived. Computational investigations have been performed to examine the quantum mechanical effects on the linear and nonlinear waves. It is found that both the linear and nonlinear properties of the IAWs are significantly affected by the inclusion of the quantum corrections. The relevance of the present investigation to dense white dwarfs (where the electron-positron annihilation can be unimportant) is discussed.

  3. Evolution of higher order nonlinear equation for the dust ion-acoustic waves in nonextensive plasma

    SciTech Connect

    Yasmin, S.; Asaduzzaman, M.; Mamun, A. A.

    2012-10-15

    There are three different types of nonlinear equations, namely, Korteweg-de Vries (K-dV), modified K-dV (mK-dV), and mixed modified K-dV (mixed mK-dV) equations, for the nonlinear propagation of the dust ion-acoustic (DIA) waves. The effects of electron nonextensivity on DIA solitary waves propagating in a dusty plasma (containing negatively charged stationary dust, inertial ions, and nonextensive q distributed electrons) are examined by solving these nonlinear equations. The basic features of mixed mK-dV (higher order nonlinear equation) solitons are found to exist beyond the K-dV limit. The properties of mK-dV solitons are compared with those of mixed mK-dV solitons. It is found that both positive and negative solitons are obtained depending on the q (nonextensive parameter).

  4. Dust ion-acoustic cnoidal waves in a plasma with two temperature superthermal electrons

    NASA Astrophysics Data System (ADS)

    Saini, N. S.; Sethi, Papihra

    2016-10-01

    An investigation of dust ion-acoustic (DIA) cnoidal waves in unmagnetized collisionless plasma consisting of two temperature superthermal electrons, inertial warm ions, and negatively charged dust grains is presented. Reductive perturbation technique has been used to derive the modified Korteweg-de Vries (mKdV) equation for the study of nonlinear periodic waves. Further, applying the Sagdeev potential approach, energy balance equation is derived. Using the expression for Sagdeev potential in expanded form, the cnoidal wave solution is determined. Both positive and negative potential (compressive and rarefactive) nonlinear DIA cnoidal structures are observed. The effects of parameters like the number density of cold electrons, superthermality of hot and cold electrons, ions to hot electrons temperature ratio, and dust to ion density ratio on the characteristics of DIA cnoidal waves are analyzed.

  5. Two-dimensional cylindrical ion-acoustic solitary and rogue waves in ultrarelativistic plasmas

    SciTech Connect

    Ata-ur-Rahman; Ali, S.; Moslem, W. M.; Mushtaq, A.

    2013-07-15

    The propagation of ion-acoustic (IA) solitary and rogue waves is investigated in a two-dimensional ultrarelativistic degenerate warm dense plasma. By using the reductive perturbation technique, the cylindrical Kadomtsev–Petviashvili (KP) equation is derived, which can be further transformed into a Korteweg–de Vries (KdV) equation. The latter admits a solitary wave solution. However, when the frequency of the carrier wave is much smaller than the ion plasma frequency, the KdV equation can be transferred to a nonlinear Schrödinger equation to study the nonlinear evolution of modulationally unstable modified IA wavepackets. The propagation characteristics of the IA solitary and rogue waves are strongly influenced by the variation of different plasma parameters in an ultrarelativistic degenerate dense plasma. The present results might be helpful to understand the nonlinear electrostatic excitations in astrophysical degenerate dense plasmas.

  6. Ion acoustic and dust acoustic waves at finite size of plasma particles

    SciTech Connect

    Andreev, Pavel A. Kuz'menkov, L. S.

    2015-03-15

    We consider the influence of the finite size of ions on the properties of classic plasmas. We focus our attention at the ion acoustic waves for electron-ion plasmas. We also consider the dusty plasmas where we account the finite size of ions and particles of dust and consider the dispersion of dust acoustic waves. The finite size of particles is a classical effect as well as the Coulomb interaction. The finite size of particles considerably contributes to the properties of the dense plasmas in the small wavelength limit. Low temperature dense plasmas, revealing the quantum effects, are also affected by the finite size of plasma particles. Consequently, it is important to consider the finite size of ions in the quantum plasmas as well.

  7. Nonlinear ion-acoustic waves in a degenerate plasma with nuclei of heavy elements

    SciTech Connect

    Hossen, M. A. Mamun, A. A.

    2015-10-15

    The ion-acoustic (IA) solitary waves propagating in a fully relativistic degenerate dense plasma (containing relativistic degenerate electron and ion fluids, and immobile nuclei of heavy elements) have been theoretically investigated. The relativistic hydrodynamic model is used to derive the Korteweg-de Vries (K-dV) equation by the reductive perturbation method. The stationary solitary wave solution of this K-dV equation is obtained to characterize the basic features of the IA solitary structures that are found to exist in such a degenerate plasma. It is found that the effects of electron dynamics, relativistic degeneracy of the plasma fluids, stationary nuclei of heavy elements, etc., significantly modify the basic properties of the IA solitary structures. The implications of this results in astrophysical compact objects like white dwarfs are briefly discussed.

  8. Propagation and oblique collision of ion-acoustic solitary waves in a magnetized dusty electronegative plasma

    SciTech Connect

    El-Labany, S. K.; Behery, E. E.; El-Shamy, E. F.

    2013-12-15

    The propagation and oblique collision of ion-acoustic (IA) solitary waves in a magnetized dusty electronegative plasma consisting of cold mobile positive ions, Boltzmann negative ions, Boltzmann electrons, and stationary positive/negative dust particles are studied. The extended Poincaré-Lighthill-Kuo perturbation method is employed to derive the Korteweg-de Vries equations and the corresponding expressions for the phase shifts after collision between two IA solitary waves. It turns out that the angle of collision, the temperature and density of negative ions, and the dust density of opposite polarity have reasonable effects on the phase shift. Clearly, the numerical results demonstrated that the IA solitary waves are delayed after the oblique collision. The current finding of this work is applicable in many plasma environments having negative ion species, such as D- and F-regions of the Earth's ionosphere and some laboratory plasma experiments.

  9. Nonlinear ion-acoustic structures in dusty plasma with superthermal electrons and positrons

    SciTech Connect

    El-Tantawy, S. A.; El-Bedwehy, N. A.; Moslem, W. M.

    2011-05-15

    Nonlinear ion-acoustic structures are investigated in an unmagnetized, four-component plasma consisting of warm ions, superthermal electrons and positrons, as well as stationary charged dust impurities. The basic set of fluid equations is reduced to modified Korteweg-de Vries equation. The latter admits both solitary waves and double layers solutions. Numerical calculations indicate that these nonlinear structures cannot exist for all physical parameters. Therefore, the existence regions for both solitary and double layers excitations have been defined precisely. Furthermore, the effects of temperature ratios of ions-to-electrons and electrons-to-positrons, positrons and dust concentrations, as well as superthermal parameters on the profiles of the nonlinear structures are investigated. Also, the acceleration and deceleration of plasma species have been highlight. It is emphasized that the present investigation may be helpful in better understanding of nonlinear structures which propagate in astrophysical environments, such as in interstellar medium.

  10. Ion-acoustic shocks with reflected ions: modelling and particle-in-cell simulations

    NASA Astrophysics Data System (ADS)

    Liseykina, T. V.; Dudnikova, G. I.; Vshivkov, V. A.; Malkov, M. A.

    2015-10-01

    > Non-relativistic collisionless shock waves are widespread in space and astrophysical plasmas and are known as efficient particle accelerators. However, our understanding of collisionless shocks, including their structure and the mechanisms whereby they accelerate particles, remains incomplete. We present here the results of numerical modelling of an ion-acoustic collisionless shock based on the one-dimensional kinetic approximation for both electrons and ions with a real mass ratio. Special emphasis is paid to the shock-reflected ions as the main driver of shock dissipation. The reflection efficiency, the velocity distribution of reflected particles and the shock electrostatic structure are studied in terms of the shock parameters. Applications to particle acceleration in geophysical and astrophysical shocks are discussed.

  11. Numerical study of ion acoustic shock waves in dense quantum plasma

    SciTech Connect

    Hanif, M.; Mirza, Arshad M.; Ali, S.; Mukhtar, Q.

    2014-03-15

    Two fluid quantum hydrodynamic equations are solved numerically to investigate the propagation characteristics of ion acoustic shock waves in an unmagnetized dense quantum plasma, whose constituents are the electrons and ions. For this purpose, we employ the standard finite difference Lax Wendroff and relaxation methods, to examine the quantum effects on the profiles of shock potential, the electron/ion number densities, and velocity even for quantum parameter at H = 2. The effects of the latter vanish in a weakly non-linear limit while obeying the KdV theory. It is shown that the evolution of the wave depends sensitively on the plasma density and the quantum parameter. Numerical results reveal that the kinks or oscillations are pronounced for large values of quantum parameter, especially at H = 2. Our results should be important to understand the shock wave excitations in dense quantum plasmas, white dwarfs, neutron stars, etc.

  12. Ion heating in a dusty plasma due to the dust/ion acoustic instability

    SciTech Connect

    Winske, D.; Gary, S.P.; Jones, M.E.

    1995-08-01

    The drift of plasma ions relative to charged grains in a dusty plasma can give rise to a dust/ion acoustic instability. The authors investigate the linear properties of the instability by numerically solving an appropriate linear dispersion equation and examine the nonlinear behavior through one-dimensional electrostatic particle simulations, in which the plasma and dust ions are treated as discrete particles and the electrons are modeled as a Boltzmann fluid. The instability is slightly weaker when the dust particles have a range of sizes, and corresponding range of charges and masses. It is argued that due to dust particles that comprise planetary rings, this process can contribute to ion heating and diffusion observed in the linear magnetosphere of Saturn. 14 refs., 4 figs.

  13. Ion-acoustic compressive and rarefactive solitons in an electron-beam plasma system

    SciTech Connect

    Yadav, L.L.; Tiwari, R.S.; Sharma, S.R. )

    1994-03-01

    Using the general formulation of reductive perturbation method, the Korteweg--de Vries (KdV) equation is derived for an electron-beam plasma with hot isothermal beam and plasma electrons and warm ions. The soliton solution of the KdV equation is discussed in detail. It is found that above a critical velocity of electron-beam two additional ion-acoustic soliton branches appear. It is found that corresponding to two linear modes, the system supports the existence of compressive as well as rarefactive solitons depending upon the plasma parameters, while corresponding to other two wave modes, the system supports only rarefactive solitons. The effect of different parameters on the characteristics of solitons have been investigated in detail.

  14. Plasma characterization using ultraviolet Thomson scattering from ion-acoustic and electron plasma waves (invited)

    NASA Astrophysics Data System (ADS)

    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.

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

    SciTech Connect

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

    2013-06-15

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

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

    NASA Astrophysics Data System (ADS)

    El-Tantawy, S. A.

    2016-08-01

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

  17. The stability of freely-propagating ion acoustic waves in 2D systems

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

    The stability of a freely-propagating ion acoustic wave (IAW) is a basic science problem that is made difficult by the need to resolve electron kinetic effects over a timescale that greatly exceeds the IAW period during numerical simulation. Recent results examining IAW stability using a 1D+1V Vlasov-Poisson solver indicate that instability is a fundamental property of IAWs that occurs over most if not all of the parameter space of relevance to ICF experiments. We present here new results addressing the fundamental question of IAW stability across a broad range of plasma conditions in a 2D+2V system using LOKI, ranging from a regime of relatively weak to a regime of relatively strong ion kinetic effects. Work performed under the auspices of the U.S. DOE by LLNL (DE-AC52-07NA27344) and funded by the LDRD Program at LLNL (12-ERD-061).

  18. Amplitude Modulator Chassis

    SciTech Connect

    Erbert, G

    2009-09-01

    The Amplitude Modulator Chassis (AMC) is the final component in the MOR system and connects directly to the PAM input through a 100-meter fiber. The 48 AMCs temporally shape the 48 outputs of the MOR using an arbitrary waveform generator coupled to an amplitude modulator. The amplitude modulation element is a two stage, Lithium Niobate waveguide device, where the intensity of the light passing through the device is a function of the electrical drive applied. The first stage of the modulator is connected to a programmable high performance Arbitrary Waveform Generator (AWG) consisting of 140 impulse generators space 250 ps apart. An arbitrary waveform is generated by independently varying the amplitude of each impulse generator and then summing the impulses together. In addition to the AWG a short pulse generator is also connected to the first stage of the modulator to provide a sub 100-ps pulse used for timing experiments. The second stage of the modulator is connect to a square pulse generator used to further attenuate any pre or post pulse light passing through the first stage of the modulator. The fast rise and fall time of the square pulse generator is also used to produce fast rise and fall times of the AWG by clipping the AWG pulse. For maximum extinction, a pulse bias voltage is applied to each stage of the modulator. A pulse voltage is applied as opposed to a DC voltage to prevent charge buildup on the modulator. Each bias voltage is adjustable to provide a minimum of 50-dB extinction. The AMC is controlled through ICCS to generate the desired temporal pulse shape. This process involves a closed-loop control algorithm, which compares the desired temporal waveform to the produced optical pulse, and iterates the programming of the AWG until the two waveforms agree within an allowable tolerance.

  19. Time evolution of nonplanar dust ion-acoustic solitary waves in a charge varying dusty plasma with superthermal electrons

    SciTech Connect

    Mayout, Saliha; Tribeche, Mouloud; Sahu, Biswajit

    2015-12-15

    A theoretical study on the nonlinear propagation of nonplanar (cylindrical and spherical) dust ion-acoustic solitary waves (DIASW) is carried out in a dusty plasma, whose constituents are inertial ions, superthermal electrons, and charge fluctuating stationary dust particles. Using the reductive perturbation theory, a modified Korteweg-de Vries equation is derived. It is shown that the propagation characteristics of the cylindrical and spherical DIA solitary waves significantly differ from those of their one-dimensional counterpart.

  20. Collective Thomson scattering measurements of the Ion Acoustic Decay Instability. Final report

    SciTech Connect

    Mizuno, K.; DeGroot, J.S.; Drake, R.P.; Seka, W.

    1993-12-31

    We have developed an uv collective Thomson scattering system for plasma produced by a short wavelength laser. The Ion Acoustic Decay Instabilities are studied in a large ({approximately}mm) scale, hot ({approximately}keV) plasma, which is relevant to a direct-driven laser fusion plasma. The IADI primary decay process is measured by the CTS. We used a random phase plate to minimize the non uniform irradiation of the interaction laser. Nevertheless, the threshold of the most unstable mode driven by the IADI is quite low. The measured threshold value agrees favorably with the theoretical value of the large scale plasma. We have also shown that the CTS from the IADI can be a good tool for measuring a local electron temperature. The measured results agree reasonably with the SAGE computer calculations. We used the real part of the wave (frequency) to estimate T{sub e}. The real part is, in general, reliable compared to the imaginary part such as the damping, and the growth rates. We have shown that the IADI can be easily excited in a large scale, hot plasma. The IADI has potentially important applications to direct drive laser fusion, and also critical surface diagnostic.

  1. Dispersive Alfven waves and Ion-acoustic Turbulence: M-I coupling at the Smallest Scales

    NASA Astrophysics Data System (ADS)

    Semeter, J. L.; Zettergren, M. D.; Diaz, M.; Stromme, A.; Nicolls, M. J.; Heinselman, C. J.

    2010-12-01

    Auroral displays exhibit coherence across multiple scales, beginning with the global auroral oval and extending down to packets of discrete arcs of <100-m width related to dispersive Alfven waves. The latter have been found to be magnetically conjugate to regions of non-thermal backscatter from the ionospheric F-region recorded by incoherent scatter radar (ISR). The phenomenological relationship between auroral morphology and ISR spectral distortions has been well established, at least in a static sense, but the theory connecting these disparate observational domains is incomplete. It is argued that considerable insight into magnetosphere-ionosphere (M-I) coupling is obtained by understanding auroral physics at these elemental scales. The purpose of this paper is twofold: (1) to provide observational evidence that not all arc-related ISR distortions fit neatly into a single category (e.g., the “Naturally Enhanced Ion-Acoustic Line” or NEIAL), and (2) to provide a critical review of candidate theoretical models to simultaneously account for the time-dependent optical and radar measurements. Evidentiary support focuses on observations of a substorm onset on 23 March 2007 (11:20 UT) by a narrow-field video-rate camera and the electronically steerable Poker Flat ISR (PFISR). Examples of ISR spectra as a function of altitude. 1: thermal backscatter, 2 and 3: enhanced backscatter conjugate to discrete aurora.

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

    SciTech Connect

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

    2014-12-15

    A study is presented for the oblique propagation of ion acoustic cnoidal waves in a magnetized plasma consisting of cold ions and two temperature superthermal electrons modelled by kappa-type distributions. Using the reductive perturbation method, the nonlinear Korteweg de-Vries equation is derived, which further gives the solutions with a special type of cnoidal elliptical functions. Both compressive and rarefactive structures are found for these cnoidal waves. Nonlinear periodic cnoidal waves are explained in terms of plasma parameters depicting the Sagdeev potential and the phase curves. It is found that the density ratio of hot electrons to ions μ significantly modifies compressive/refractive wave structures. Furthermore, the combined effects of superthermality of cold and hot electrons κ{sub c},κ{sub h}, cold to hot electron temperature ratio σ, angle of propagation and ion cyclotron frequency ω{sub ci} have been studied in detail to analyze the height and width of compressive/refractive cnoidal waves. The findings in the present study could have important implications in understanding the physics of electrostatic wave structures in the Saturn's magnetosphere where two temperature superthermal electrons are present.

  3. Coupled nonlinear drift and ion acoustic waves in dense dissipative electron-positron-ion magnetoplasmas

    NASA Astrophysics Data System (ADS)

    Masood, W.; Karim, S.; Shah, H. A.; Siddiq, M.

    2009-11-01

    Linear and nonlinear propagation characteristics of drift ion acoustic waves are investigated in an inhomogeneous electron-positron-ion (e-p-i) quantum magnetoplasma with neutrals in the background using the well known quantum hydrodynamic model. In this regard, Korteweg-de Vries-Burgers (KdVB) and Kadomtsev-Petviashvili-Burgers (KPB) equations are obtained. Furthermore, the solutions of KdVB and KPB equations are presented by using the tangent hyperbolic (tanh) method. The variation in the shock profile with the quantum Bohm potential, collision frequency, and the ratio of drift to shock velocity in the comoving frame, v*/u, is also investigated. It is found that increasing the positron concentration and collision frequency decreases the strength of the shock. It is also shown that when the localized structure propagates with velocity greater than the diamagnetic drift velocity (i.e., u >v*), the shock strength decreases. However, the shock strength is observed to increase when the localized structure propagates with velocity less than that of drift velocity (i.e., u

  4. Nonlinear interaction of kinetic Alfvén waves and ion acoustic waves in coronal loops

    NASA Astrophysics Data System (ADS)

    Sharma, Prachi; Yadav, Nitin; Sharma, R. P.

    2016-05-01

    Over the years, coronal heating has been the most fascinating question among the scientific community. In the present article, a heating mechanism has been proposed based on the wave-wave interaction. Under this wave-wave interaction, the high frequency kinetic Alfvén wave interacts with the low frequency ion acoustic wave. These waves are three dimensionally propagating and nonlinearly coupled through ponderomotive nonlinearity. A numerical code based on pseudo-spectral technique has been developed for solving these normalized dynamical equations. Localization of kinetic Alfvén wave field has been examined, and magnetic power spectrum has also been analyzed which shows the cascading of energy to higher wavenumbers, and this cascading has been found to have Kolmogorov scaling, i.e., k-5 /3 . A breakpoint appears after Kolmogorov scaling and next to this spectral break; a steeper scaling has been obtained. The presented nonlinear interaction for coronal loops plasmas is suggested to generate turbulent spectrum having Kolmogorov scaling in the inertial range and steepened scaling in the dissipation range. Since Kolmogorov turbulence is considered as the main source for coronal heating; therefore, the suggested mechanism will be a useful tool to understand the mystery of coronal loop heating through Kolmogorov turbulence and dissipation.

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

    SciTech Connect

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

    2015-03-15

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

  6. Transition of ion-acoustic perturbations in multicomponent plasma with negative ions

    SciTech Connect

    Sharma, Sumita Kumari; Devi, Kavita; Adhikary, Nirab Chandra; Bailung, Heremba

    2008-08-15

    Evolution of ion-acoustic compressive (positive) and rarefactive (negative) perturbations in a multicomponent plasma with negative ions has been investigated in a double plasma device. Transition of compressive solitons in electron-positive ion plasma, into a dispersing train of oscillations in a multicomponent plasma, when the negative ion concentration r exceeds a critical value r{sub c}, has been observed. On the other hand, an initial rarefactive perturbation initially evolves into a dispersing train of oscillations in electron-positive ion plasma and transforms into rarefactive solitons in a multicomponent plasma when the negative ion concentration is higher than the critical value. The Mach velocity and width of the compressive and rarefactive solitons are measured. The compressive solitons in the range 0r{sub c} have different characteristics than the Korteweg-de Vries (KdV) solitons at r=0 and modified KdV solitons at r=r{sub c}. A nonlinear differential equation having two terms to account for the lower and higher order nonlinearity has been used to explain the observed results.

  7. Auroral ion acoustic wave enhancement observed with a radar interferometer system

    NASA Astrophysics Data System (ADS)

    Schlatter, N. M.; Belyey, V.; Gustavsson, B.; Ivchenko, N.; Whiter, D.; Dahlgren, H.; Tuttle, S.; Grydeland, T.

    2015-07-01

    Measurements of naturally enhanced ion acoustic line (NEIAL) echoes obtained with a five-antenna interferometric imaging radar system are presented. The observations were conducted with the European Incoherent SCATter (EISCAT) radar on Svalbard and the EISCAT Aperture Synthesis Imaging receivers (EASI) installed at the radar site. Four baselines of the interferometer are used in the analysis. Based on the coherence estimates derived from the measurements, we show that the enhanced backscattering region is of limited extent in the plane perpendicular to the geomagnetic field. Previously it has been argued that the enhanced backscatter region is limited in size; however, here the first unambiguous observations are presented. The size of the enhanced backscatter region is determined to be less than 900 × 500 m, and at times less than 160 m in the direction of the longest antenna separation, assuming the scattering region to have a Gaussian scattering cross section in the plane perpendicular to the geomagnetic field. Using aperture synthesis imaging methods volumetric images of the NEIAL echo are obtained showing the enhanced backscattering region to be aligned with the geomagnetic field. Although optical auroral emissions are observed outside the radar look direction, our observations are consistent with the NEIAL echo occurring on field lines with particle precipitation.

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

    SciTech Connect

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

    2014-09-15

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

  9. The Langmuir's Paradox: Can the Ion Acoustic Instability at the Sheath Edge Thermalize the Ions Too?

    NASA Astrophysics Data System (ADS)

    Yip, Chi-Shung; Hershkowitz, Noah; Severn, Greg

    2013-09-01

    Recently a theoretical prediction was that in single-species plasmas, ion-ion collisional friction is enhanced by the ion acoustic instability. The theory predicted that the instability will not only enhance the thermalization of the electrons, but will also, near the sheath-edge, thermalize the non-Maxwellian tail of the ion velocity distribution function (IVDF), caused by charge exchange in the presheath. The theory also predicted that this instability disappears through collisional damping as neutral pressure of the plasma increases. This experiment aims to verify this theory by measuring the IVDFs near the sheath edge in a multi-dipole chamber discharge in Argon and Xenon gas for a variety of neutral pressures and electron temperatures. The threshold parameters of the phenomenon are explored. The IVDFs are determined by Laser-Induced Florescence, the electron temperature is measured by a Langmuir probe and the plasma potential towards the boundary is measured by an emissive probe. DOE Grant nos. DE-SC0001939, DE FG02- 03ER54728, and NSF No. CBET0903832.

  10. Modification of the formation of high-Mach number electrostatic shock-like structures by the ion acoustic instability

    SciTech Connect

    Dieckmann, M. E.; Sarri, G.; Doria, D.; Borghesi, M.; Pohl, M.

    2013-10-15

    The formation of unmagnetized electrostatic shock-like structures with a high Mach number is examined with one- and two-dimensional particle-in-cell (PIC) simulations. The structures are generated through the collision of two identical plasma clouds, which consist of equally hot electrons and ions with a mass ratio of 250. The Mach number of the collision speed with respect to the initial ion acoustic speed of the plasma is set to 4.6. This high Mach number delays the formation of such structures by tens of inverse ion plasma frequencies. A pair of stable shock-like structures is observed after this time in the 1D simulation, which gradually evolves into electrostatic shocks. The ion acoustic instability, which can develop in the 2D simulation but not in the 1D one, competes with the nonlinear process that gives rise to these structures. The oblique ion acoustic waves fragment their electric field. The transition layer, across which the bulk of the ions change their speed, widens and their speed change is reduced. Double layer-shock hybrid structures develop.

  11. Modification of the formation of high-Mach number electrostatic shock-like structures by the ion acoustic instability

    NASA Astrophysics Data System (ADS)

    Dieckmann, M. E.; Sarri, G.; Doria, D.; Pohl, M.; Borghesi, M.

    2013-10-01

    The formation of unmagnetized electrostatic shock-like structures with a high Mach number is examined with one- and two-dimensional particle-in-cell (PIC) simulations. The structures are generated through the collision of two identical plasma clouds, which consist of equally hot electrons and ions with a mass ratio of 250. The Mach number of the collision speed with respect to the initial ion acoustic speed of the plasma is set to 4.6. This high Mach number delays the formation of such structures by tens of inverse ion plasma frequencies. A pair of stable shock-like structures is observed after this time in the 1D simulation, which gradually evolves into electrostatic shocks. The ion acoustic instability, which can develop in the 2D simulation but not in the 1D one, competes with the nonlinear process that gives rise to these structures. The oblique ion acoustic waves fragment their electric field. The transition layer, across which the bulk of the ions change their speed, widens and their speed change is reduced. Double layer-shock hybrid structures develop.

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

    SciTech Connect

    Saha, Asit E-mail: prasantachatterjee1@rediffmail.com; Pal, Nikhil; Chatterjee, Prasanta E-mail: prasantachatterjee1@rediffmail.com

    2014-10-15

    The dynamic behavior of ion acoustic waves in electron-positron-ion magnetoplasmas with superthermal electrons and positrons has been investigated in the framework of perturbed and non-perturbed Kadomtsev-Petviashili (KP) equations. Applying the reductive perturbation technique, we have derived the KP equation in electron-positron-ion magnetoplasma with kappa distributed electrons and positrons. Bifurcations of ion acoustic traveling waves of the KP equation are presented. Using the bifurcation theory of planar dynamical systems, the existence of the solitary wave solutions and the periodic traveling wave solutions has been established. Two exact solutions of these waves have been derived depending on the system parameters. Then, using the Hirota's direct method, we have obtained two-soliton and three-soliton solutions of the KP equation. The effect of the spectral index κ on propagations of the two-soliton and the three-soliton has been shown. Considering an external periodic perturbation, we have presented the quasi periodic behavior of ion acoustic waves in electron-positron-ion magnetoplasmas.

  13. GENERAL Holomorphic Factorization of Superstring Scattering Amplitudes

    NASA Astrophysics Data System (ADS)

    Simon, Davis

    2011-01-01

    The holomorphic factorization of the superstring partition function is verified at arbitrary genus. The evaluation of scattering amplitudes and the implications of genus-dependent estimates on the string coupling are given.

  14. Influences of shear in the ion parallel drift velocity and of inhomogeneous perpendicular electric field on generation of oblique ion acoustic waves

    NASA Astrophysics Data System (ADS)

    Ilyasov, Askar; Chernyshov, Alexander; Mogilevsky, Mikhail; Golovchanskaya, Irina; Kozelov, Boris

    2016-03-01

    It is well known that the broadband electrostatic turbulence observed in the topside auroral ionosphere can be identified with electrostatic ion cyclotron and/or oblique ion acoustic waves. Under certain conditions generation of the ion cyclotron modes is inhibited, so that the oblique ion acoustic waves become the prevailing part of the broadband noise. While generation of ion cyclotron waves by the inhomogeneous distribution of energy density (IEDD) instability has been actively studied in recent years, much less attention was paid to the excitation of ion acoustic waves by means of the IEDD instability. In this work, influence of shear in the ion parallel drift velocities and of inhomogeneous perpendicular electric field on generation of nonlocal oblique ion acoustic mode is studied. It is demonstrated that the shear of the ion parallel drift velocities can generate ion acoustic waves. It is shown that this mechanism of instability development provides broadband spectrum in the frequency range around 0.1 of ion gyrofrequency, and thus, this instability can be invoked to explain the observed broadband electrostatic turbulence in the auroral region. Effect of the main background plasma parameters on excitation of oblique ion acoustic waves is analyzed.

  15. Multicomponent kinetic simulation of Bernstein–Greene–Kruskal modes associated with ion acoustic and dust-ion acoustic excitations in electron-ion and dusty plasmas

    SciTech Connect

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

    2014-04-15

    A series of numerical simulations based on a recurrence-free Vlasov kinetic algorithm presented earlier [Abbasi et al., Phys. Rev. E 84, 036702 (2011)] are reported. Electron-ion plasmas and three-component (electron-ion-dust) dusty, or complex, plasmas are considered, via independent simulations. Considering all plasma components modeled through a kinetic approach, the nonlinear behavior of ionic scale acoustic excitations is investigated. The focus is on Bernstein–Greene–Kruskal (BGK) modes generated during the simulations. In particular, we aim at investigating the parametric dependence of the characteristics of BGK structures, namely of their time periodicity (τ{sub trap}) and their amplitude, on the electron-to-ion temperature ratio and on the dust concentration. In electron-ion plasma, an exponential relation between τ{sub trap} and the amplitude of BGK modes and the electron-to-ion temperature ratio is observed. It is argued that both characteristics, namely, the periodicity τ{sub trap} and amplitude, are also related to the size of the phase-space vortex which is associated with BGK mode creation. In dusty plasmas, BGK modes characteristics appear to depend on the dust particle density linearly.

  16. Arbitrary Metrics in Psychology

    ERIC Educational Resources Information Center

    Blanton, Hart; Jaccard, James

    2006-01-01

    Many psychological tests have arbitrary metrics but are appropriate for testing psychological theories. Metric arbitrariness is a concern, however, when researchers wish to draw inferences about the true, absolute standing of a group or individual on the latent psychological dimension being measured. The authors illustrate this in the context of 2…

  17. Effects of dust size distribution on dust negative ion acoustic solitary waves in a magnetized dusty plasma

    SciTech Connect

    Ma, Yi-Rong; Qi, Xin; Sun, Jian-An; Duan, Wen-Shan; Yang, Lei

    2013-08-15

    Dust negative ion acoustic solitary waves in a magnetized multi-ion dusty plasma containing hot isothermal electron, ions (light positive ions and heavy negative ions) and extremely massive charge fluctuating dust grains are investigated by employing the reductive perturbation method. How the dust size distribution affect the height and the thickness of the nonlinear solitary wave are given. It is noted that the characteristic of the solitary waves are different with the different dust size distribution. The magnitude of the external magnetic field also affects the solitary wave form.

  18. Ion-acoustic solitons and vortices in the e-p-i plasma with field-aligned inhomogeneous flow

    NASA Astrophysics Data System (ADS)

    Saleem, H.; Ali, S.; Saeed, U.; Haque, Q.

    2016-09-01

    The linear and nonlinear characteristics of the ion-acoustic waves are studied in a magnetized electron-positron-ion (e-p-i) plasma with shear flow along the ambient magnetic field. The sheared flow reduces or enhances the frequency of the wave strongly depending upon its polarity and nonlinear equations yield stable electrostatic structures in the form of solitons and vortices. Therefore, it is suggested that in the presence of shear flow, the electrostatic fields with real frequency ωr < csk (where cs is the ion sound speed) exist in e-p-i plasmas. Numerical solutions are discussed using the normalized parameters.

  19. Modulational instability of ion-acoustic waves in a plasma with a q-nonextensive electron velocity distribution

    SciTech Connect

    Bains, A. S.; Gill, T. S.; Tribeche, Mouloud

    2011-02-15

    The modulational instability (MI) of ion-acoustic waves (IAWs) in a two-component plasma is investigated in the context of the nonextensive statistics proposed by Tsallis [J. Stat. Phys. 52, 479 (1988)]. Using the reductive perturbation method, the nonlinear Schroedinger equation (NLSE) which governs the MI of the IAWs is obtained. The presence of the nonextensive electron distribution is shown to influence the MI of the waves. Three different ranges of the nonextensive q-parameter are considered and in each case the MI sets in under different conditions. Furthermore, the effects of the q-parameter on the growth rate of MI are discussed in detail.

  20. Time-fractional Gardner equation for ion-acoustic waves in negative-ion-beam plasma with negative ions and nonthermal nonextensive electrons

    SciTech Connect

    Guo, Shimin Mei, Liquan; Zhang, Zhengqiang

    2015-05-15

    Nonlinear propagation of ion-acoustic waves is investigated in a one-dimensional, unmagnetized plasma consisting of positive ions, negative ions, and nonthermal electrons featuring Tsallis distribution that is penetrated by a negative-ion-beam. The classical Gardner equation is derived to describe nonlinear behavior of ion-acoustic waves in the considered plasma system via reductive perturbation technique. We convert the classical Gardner equation into the time-fractional Gardner equation by Agrawal's method, where the time-fractional term is under the sense of Riesz fractional derivative. Employing variational iteration method, we construct solitary wave solutions of the time-fractional Gardner equation with initial condition which depends on the nonlinear and dispersion coefficients. The effect of the plasma parameters on the compressive and rarefactive ion-acoustic solitary waves is also discussed in detail.

  1. Development of a new plasma diagnostic of the critical surface and studies of the ion acoustic decay instability using collective Thomson scattering. Final report

    SciTech Connect

    Mizuno, K.; DeGroot, J.S.; Seka, W.; Drake, R.P.

    1992-08-01

    We have developed 5-channel collective Thomson scattering system to measure the ion acoustic wave excited by the ion acoustic wave decay instabilities. The multichannel collective Thomson scattering technique was established with 4{omega} probe laser beam using GDL laser system at LLE, Univ. of Rochester. We have obtained the ionic charge state Z by measuring the second harmonic emission from the ion acoustic decay instability. The LASNEX computer simulation calculations have been carried out. The experimental results agree very well with the LASNEX computer simulation results with the flux number f=0.l. In high power laser regime, the spectrum become broad, and the {Delta}{gamma} decreases indicating that the turbulent like spectrum is observed. In order to understand the experimental results, we have developed a theory to study absorption of laser and heat transport. This new theory includes the temporal evolution of the heat conduction region. The results agree with flux-limited hydrodynamic simulations.

  2. Development of a new plasma diagnostic of the critical surface and studies of the ion acoustic decay instability using collective Thomson scattering

    SciTech Connect

    Mizuno, K.; DeGroot, J.S. ); Seka, W. . Lab. of Laser Energetics); Drake, R.P. )

    1992-01-01

    We have developed 5-channel collective Thomson scattering system to measure the ion acoustic wave excited by the ion acoustic wave decay instabilities. The multichannel collective Thomson scattering technique was established with 4{omega} probe laser beam using GDL laser system at LLE, Univ. of Rochester. We have obtained the ionic charge state Z by measuring the second harmonic emission from the ion acoustic decay instability. The LASNEX computer simulation calculations have been carried out. The experimental results agree very well with the LASNEX computer simulation results with the flux number f=0.l. In high power laser regime, the spectrum become broad, and the {Delta}{gamma} decreases indicating that the turbulent like spectrum is observed. In order to understand the experimental results, we have developed a theory to study absorption of laser and heat transport. This new theory includes the temporal evolution of the heat conduction region. The results agree with flux-limited hydrodynamic simulations.

  3. Arguments for fundamental emission by the parametric process L yields T + S in interplanetary type III bursts. [langmuir, electromagnetic, ion acoustic waves (L, T, S)

    NASA Technical Reports Server (NTRS)

    Cairns, I. H.

    1984-01-01

    Observations of low frequency ion acoustic-like waves associated with Langmuir waves present during interplanetary Type 3 bursts are used to study plasma emission mechanisms and wave processes involving ion acoustic waves. It is shown that the observed wave frequency characteristics are consistent with the processes L yields T + S (where L = Langmuir waves, T = electromagnetic waves, S = ion acoustic waves) and L yields L' + S proceeding. The usual incoherent (random phase) version of the process L yields T + S cannot explain the observed wave production time scale. The clumpy nature of the observed Langmuir waves is vital to the theory of IP Type 3 bursts. The incoherent process L yields T + S may encounter difficulties explaining the observed Type 3 brightness temperatures when Langmuir wave clumps are incorporated into the theory. The parametric process L yields T + S may be the important emission process for the fundamental radiation of interplanetary Type 3 bursts.

  4. Modulation instability and dissipative ion-acoustic structures in collisional nonthermal electron-positron-ion plasma: solitary and shock waves

    NASA Astrophysics Data System (ADS)

    Guo, Shimin; Mei, Liquan; He, Ya-Ling; Ma, Chenchen; Sun, Youfa

    2016-10-01

    The nonlinear behavior of an ion-acoustic wave packet is investigated in a three-component plasma consisting of warm ions, nonthermal electrons and positrons. The nonthermal components are assumed to be inertialess and hot where they are modeled by the kappa distribution. The relevant processes, including the kinematic viscosity amongst the plasma constituents and the collision between ions and neutrals, are taken into consideration. It is shown that the dynamics of the modulated ion-acoustic wave is governed by the generalized complex Ginzburg-Landau equation with a linear dissipative term. The dispersion relation and modulation instability criterion for the generalized complex Ginzburg-Landau equation are investigated numerically. In the general dissipation regime, the effect of the plasma parameters on the dissipative solitary (dissipative soliton) and shock waves is also discussed in detail. The project is supported by NSF of China (11501441, 11371289, 11371288), National Natural Science Foundation of China (U1261112), China Postdoctoral Science Foundation (2014M560756), and Fundamental Research Funds for the Central Universities (xjj2015067).

  5. Stability of dust ion acoustic solitary waves in a collisionless unmagnetized nonthermal plasma in presence of isothermal positrons

    NASA Astrophysics Data System (ADS)

    Sardar, Sankirtan; Bandyopadhyay, Anup; Das, K. P.

    2016-07-01

    A three-dimensional KP (Kadomtsev Petviashvili) equation is derived here describing the propagation of weakly nonlinear and weakly dispersive dust ion acoustic wave in a collisionless unmagnetized plasma consisting of warm adiabatic ions, static negatively charged dust grains, nonthermal electrons, and isothermal positrons. When the coefficient of the nonlinear term of the KP-equation vanishes an appropriate modified KP (MKP) equation describing the propagation of dust ion acoustic wave is derived. Again when the coefficient of the nonlinear term of this MKP equation vanishes, a further modified KP equation is derived. Finally, the stability of the solitary wave solutions of the KP and the different modified KP equations are investigated by the small-k perturbation expansion method of Rowlands and Infeld [J. Plasma Phys. 3, 567 (1969); 8, 105 (1972); 10, 293 (1973); 33, 171 (1985); 41, 139 (1989); Sov. Phys. - JETP 38, 494 (1974)] at the lowest order of k, where k is the wave number of a long-wavelength plane-wave perturbation. The solitary wave solutions of the different evolution equations are found to be stable at this order.

  6. Modulational instability of ion acoustic waves in e-p-i plasmas with electrons and positrons following a q-nonextensive distribution

    SciTech Connect

    Eslami, Parvin; Mottaghizadeh, Marzieh; Pakzad, Hamid Reza

    2011-10-15

    The propagation of ion acoustic waves (IAWs) in plasmas composed of ions and nonextensive electrons and positrons is investigated. By means of the reduction perturbation technique, a nonlinear Schroedinger equation is derived and the modulation instability (MI) of ion acoustic waves is analyzed in detail. The effects of different ranges of the nonextensive parameter q on the MI are studied. The growth rate of the MI is also given for different values of the q parameter. It is also found that the ratio of the electron temperature to positron temperature and the ratio of the positron density to electron density modify the nature of IAWs instability and the solitary structures.

  7. Ion Acoustic Wave Frequencies and Onset Times During Type 3 Solar Radio Bursts

    NASA Technical Reports Server (NTRS)

    Cairns, Iver H.; Robinson, P. A.

    1995-01-01

    Conflicting interpretations exist for the low-frequency ion acoustic (S) waves often observed by ISEE 3 in association with intense Langmuir (L) waves in the source regions of type III solar radio bursts near 1 AU. Two indirect lines of observational evidence, as well as plasma theory, suggest they are produced by the electrostatic (ES) decay L yields L(PRIME) + S. However, contrary to theoretical predictions, an existing analysis of the wave frequencies instead favors the electromagnetic (EM) decays L yields T + S, where T denotes an EM wave near the plasma frequency. This conflict is addressed here by comparing the observed wave frequencies and onset times with theoretical predictions for the ES and EM decays, calculated using the time-variable electron beam and magnetic field orientation data, rather than the nominal values used previously. Field orientation effects and beam speed variations are shown analytically to produce factor-of-three effects, greater than the difference in wave frequencies predicted for the ES and EM decays; effects of similar magnitude occur in the events analyzed here. The S-wave signals are extracted by hand from a sawtooth noise background, greatly improving the association between S waves and intense L waves. Very good agreement exists between the time-varying predictions for the ES decay and the frequencies of most (but not all) wave bursts. The waves occur only after the ES decay becomes kinematically allowed, which is consistent with the ES decay proceeding and producing most of the observed signals. Good agreement exists between the EM decay's predictions and a significant fraction of the S-wave observations while the EM decay is kinematically allowed. The wave data are not consistent, however, with the EM decay being the dominant nonlinear process. Often the observed waves are sufficiently broadband to overlap simultaneously the frequency ranges predicted for the ES and EM decays. Coupling the dominance of the ES decay with this

  8. Transverse instability of ion acoustic solitons in a magnetized plasma including -nonextensive electrons and positrons

    NASA Astrophysics Data System (ADS)

    Akhtar, N.; El-Taibany, W. F.; Mahmood, S.; Behery, E. E.; Khan, S. A.; Ali, S.; Hussain, S.

    2015-10-01

    > . The magnetic field has no effect on the amplitude of the IASW, whereas the obliqueness angle of the wave propagation, the ion-to-electron temperature ratio and positron-to-ion density concentration ratio affect both the amplitude and the width of the solitary wave structures. The transverse instability analysis illustrates that the one soliton solution has a constant growth rate, and it suffers from instability in the transverse direction. The relevance of the present study to astrophysical space plasmas is also discussed.

  9. Multi-dimensional instability of dust-ion-acoustic solitary structure with opposite polarity ions and non-thermal electrons

    NASA Astrophysics Data System (ADS)

    Haider, M. M.; Rahman, O.

    2016-07-01

    An attempt has been made to study the multi-dimensional instability of dust-ion-acoustic (DIA) solitary waves (SWs) in magnetized multi-ion plasmas containing opposite polarity ions, opposite polarity dusts and non-thermal electrons. First of all, we have derived Zakharov-Kuznetsov (ZK) equation to study the DIA SWs in this case using reductive perturbation method as well as its solution. Small-k perturbation technique was employed to find out the instability criterion and growth rate of such a wave which can give a guideline in understanding the space and laboratory plasmas, situated in the D-region of the Earth's ionosphere, mesosphere, and solar photosphere, as well as the microelectronics plasma processing reactors.

  10. Modulational instability of ion-acoustic waves in a plasma with two-temperature kappa-distributed electrons

    NASA Astrophysics Data System (ADS)

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

    2014-08-01

    Existence and characteristics of ion-acoustic (IA) wave modulation are studied in a plasma with two-temperature electron satisfying kappa distribution. Based on the multiple time scales perturbation, a nonlinear Schrödinger equation (NLS) is derived. Similar to the case of double Maxwellian electrons, both polarities of envelope soliton can exist over restricted ranges of the fractional hot electron density ratio and two-temperature superthermal electrons. The transition from stable dark solitons to unstable bright ones shifts to the smaller wavelength regions in the presence of cool and hot superthermal electrons. It is shown that the small values of the hot electron populations leads to shrinking the modulation instability region. It is also found the instability growth rate reduces due to the presence of hot electrons. The result of present investigation contributes to the physics of wave modulation in Saturn's magnetosphere where two-temperature electrons with kappa distribution exist.

  11. Low intensity dust ion-acoustic shock waves due to dust charge fluctuation in a nonextensive dusty plasma

    SciTech Connect

    Alinejad, H.; Shahmansory, M.

    2012-08-15

    The properties of low intensity dust ion acoustic shock waves are studied in a charge varying dusty plasma with nonextensive electrons. Owing to the departure from the Maxwellian electron distribution to a nonextensive one, the modified electrostatic charging of a spherical dust particle in plasma with ion streaming speed is considered. Based on the weakly nonlinear analysis, a new relationship between the low intensity localized disturbances and nonextensive electrons is derived. It is found that both strength and steepness of shock structures arise as the electrons evolve far from their thermodynamic equilibrium in such plasma with parameter ranges corresponding to Saturn's rings. It is also shown that the ion temperature and population of electrons reduce the possibility of the formation of the shock profile.

  12. Modulational instability of ion-acoustic waves in plasma with a q-nonextensive nonthermal electron velocity distribution

    SciTech Connect

    Bouzit, Omar Tribeche, Mouloud E-mail: mtribeche@usthb.dz; Bains, A. S.

    2015-08-15

    Modulation instability of ion-acoustic waves (IAWs) is investigated in a collisionless unmagnetized one dimensional plasma, containing positive ions and electrons following the mixed nonextensive nonthermal distribution [Tribeche et al., Phys. Rev. E 85, 037401 (2012)]. Using the reductive perturbation technique, a nonlinear Schrödinger equation which governs the modulation instability of the IAWs is obtained. Valid range of plasma parameters has been fixed and their effects on the modulational instability discussed in detail. We find that the plasma supports both bright and dark solutions. The valid domain for the wave number k where instabilities set in varies with both nonextensive parameter q as well as non thermal parameter α. Moreover, the analysis is extended for the rational solutions of IAWs in the instability regime. Present study is useful for the understanding of IAWs in the region where such mixed distribution may exist.

  13. Multi-dimensional instability of obliquely propagating ion acoustic solitary waves in electron-positron-ion superthermal magnetoplasmas

    NASA Astrophysics Data System (ADS)

    EL-Shamy, E. F.

    2014-08-01

    The solitary structures of multi-dimensional ion-acoustic solitary waves (IASWs) have been considered in magnetoplasmas consisting of electron-positron-ion with high-energy (superthermal) electrons and positrons are investigated. Using a reductive perturbation method, a nonlinear Zakharov-Kuznetsov equation is derived. The multi-dimensional instability of obliquely propagating (with respect to the external magnetic field) IASWs has been studied by the small-k (long wavelength plane wave) expansion perturbation method. The instability condition and the growth rate of the instability have been derived. It is shown that the instability criterion and their growth rate depend on the parameter measuring the superthermality, the ion gyrofrequency, the unperturbed positrons-to-ions density ratio, the direction cosine, and the ion-to-electron temperature ratio. Clearly, the study of our model under consideration is helpful for explaining the propagation and the instability of IASWs in space observations of magnetoplasmas with superthermal electrons and positrons.

  14. Ion-acoustic double layers in a five component cometary plasma with kappa described electrons and ions

    NASA Astrophysics Data System (ADS)

    Michael, Manesh; Venugopal, C.; Sreekala, G.; Willington, Neethu Theresa; Sebastian, Sijo

    2016-07-01

    We investigate the propagation characteristics of Ion-acoustic solitons and double layers in a five component cometary plasma consisting of positively and negatively charged oxygen ions, kappa described hydrogen ions, hot solar electrons, and slightly colder cometary electrons. The KdV and modified KdV equations are derived for the system and its solution is plotted for different kappa values and negatively charged oxygen ion densities. It is found that the strength of double layer increases with increasing spectral indices. It, however, decreases with increasing negatively charged oxygen ion densities. The parameter for the transition from compressive to rarefactive soliton is also specified. The presence of negatively charged oxygen ions can significantly affect the nonlinearity coefficients (both quadratic and cubic) of a double layer.

  15. A new (2+1) dimensional integrable evolution equation for an ion acoustic wave in a magnetized plasma

    SciTech Connect

    Mukherjee, Abhik Janaki, M. S. Kundu, Anjan

    2015-07-15

    A new, completely integrable, two dimensional evolution equation is derived for an ion acoustic wave propagating in a magnetized, collisionless plasma. The equation is a multidimensional generalization of a modulated wavepacket with weak transverse propagation, which has resemblance to nonlinear Schrödinger (NLS) equation and has a connection to Kadomtsev-Petviashvili equation through a constraint relation. Higher soliton solutions of the equation are derived through Hirota bilinearization procedure, and an exact lump solution is calculated exhibiting 2D structure. Some mathematical properties demonstrating the completely integrable nature of this equation are described. Modulational instability using nonlinear frequency correction is derived, and the corresponding growth rate is calculated, which shows the directional asymmetry of the system. The discovery of this novel (2+1) dimensional integrable NLS type equation for a magnetized plasma should pave a new direction of research in the field.

  16. Multi-dimensional instability of obliquely propagating ion acoustic solitary waves in electron-positron-ion superthermal magnetoplasmas

    SciTech Connect

    EL-Shamy, E. F.

    2014-08-15

    The solitary structures of multi–dimensional ion-acoustic solitary waves (IASWs) have been considered in magnetoplasmas consisting of electron-positron-ion with high-energy (superthermal) electrons and positrons are investigated. Using a reductive perturbation method, a nonlinear Zakharov-Kuznetsov equation is derived. The multi-dimensional instability of obliquely propagating (with respect to the external magnetic field) IASWs has been studied by the small-k (long wavelength plane wave) expansion perturbation method. The instability condition and the growth rate of the instability have been derived. It is shown that the instability criterion and their growth rate depend on the parameter measuring the superthermality, the ion gyrofrequency, the unperturbed positrons-to-ions density ratio, the direction cosine, and the ion-to-electron temperature ratio. Clearly, the study of our model under consideration is helpful for explaining the propagation and the instability of IASWs in space observations of magnetoplasmas with superthermal electrons and positrons.

  17. Dust ion-acoustic shock waves in charge varying dusty plasmas with electrons having vortexlike velocity distribution

    SciTech Connect

    Alinejad, H.; Tribeche, M.

    2010-12-15

    A weakly nonlinear analysis is carried out to investigate the properties of dust ion-acoustic shock waves in a charge varying dusty plasma with vortexlike electron distribution. We use the ionization model, hot ions with equilibrium streaming speed and a trapped electron charging current derived from the well-known orbit limited motion theory. A new modified Burger equation is derived. Besides nonlinear trapping, this equation involves two kinds of dissipation (the anomalous one inherent to nonadiabatic dust charge fluctuation and the one due to the particle loss and ionization). These two kinds of dissipation can act concurrently. The traveling wave solution has been acquired by employing the modified extended tanh-function method. The shocklike solution is numerically analyzed based on the typical numerical data from laboratory dusty plasma devices. It is found that ion temperature, trapped particles, and weak dissipations significantly modify the shock structures.

  18. The effects of Bohm potential on ion-acoustic solitary waves interaction in a nonplanar quantum plasma

    NASA Astrophysics Data System (ADS)

    Li, Sheng-Chang

    2010-08-01

    The interaction of ion-acoustic solitary waves (IASWs) in a nonplanar unmagnetized quantum plasma consisting of electrons, positrons, and ions are studied by employing the quantum hydrodynamic model and the Korteweg-de Vries description. We provide the theoretical predictions about the phase shifts for the compressive IASWs and the rarefactive IASWs collisions, respectively. The effects of the positron to electron Fermi temperature ratio, the positron to ion number density ratio, and the quantum Bohm potential on phase shift are investigated. It is found that these factors can significantly modify the properties of the IASWs collisions. In particular, we find that the variations of phase shifts with quantum Bohm potential for two types of IASWs are apparently different. The validity of the results of present study is also pointed out.

  19. Ion-acoustic supersolitons in plasmas with two-temperature electrons: Boltzmann and kappa distributions

    SciTech Connect

    Verheest, Frank; Hellberg, Manfred A.; Kourakis, Ioannis

    2013-08-15

    Acoustic supersolitons arise when a plasma model is able to support three consecutive local extrema of the Sagdeev pseudopotential between the undisturbed conditions and an accessible root. This leads to a characteristic electric field signature, where a simple bipolar shape is enriched by subsidiary maxima. Large-amplitude nonlinear acoustic modes are investigated, using a pseudopotential approach, for plasmas containing two-temperature electrons having Boltzmann or kappa distributions, in the presence of cold fluid ions. The existence domains for positive supersolitons are derived in a methodological way, both for structure velocities and amplitudes, in terms of plasma compositional parameters. In addition, typical pseudopotentials, soliton, and electric field profiles have been given to illustrate that positive supersolitons can be found in the whole range of electron distributions from Maxwellian to a very hard nonthermal spectrum in kappa. However, it is found that the parameter ranges that support supersolitons vary significantly over the wide range of kappa considered.

  20. Arbitrary waveform generator

    NASA Astrophysics Data System (ADS)

    Blackmon, Fletcher A.

    1993-11-01

    An arbitrary waveform generator is capable of producing pulse or continuous waveform signals. It utilizes an EPROM that sends out selected stored digital signals under control of a microprocessor and auxiliary equipment comprised of a clock and an address sequencer. A digital to analog converter receives the digital signals from the EPROM and converts them to analog signals.

  1. Ion-acoustic solitons, double layers and rogue waves in plasma having superthermal electrons

    NASA Astrophysics Data System (ADS)

    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

  2. How arbitrary is language?

    PubMed

    Monaghan, Padraic; Shillcock, Richard C; Christiansen, Morten H; Kirby, Simon

    2014-09-19

    It is a long established convention that the relationship between sounds and meanings of words is essentially arbitrary--typically the sound of a word gives no hint of its meaning. However, there are numerous reported instances of systematic sound-meaning mappings in language, and this systematicity has been claimed to be important for early language development. In a large-scale corpus analysis of English, we show that sound-meaning mappings are more systematic than would be expected by chance. Furthermore, this systematicity is more pronounced for words involved in the early stages of language acquisition and reduces in later vocabulary development. We propose that the vocabulary is structured to enable systematicity in early language learning to promote language acquisition, while also incorporating arbitrariness for later language in order to facilitate communicative expressivity and efficiency.

  3. Sandia's Arbitrary Waveform MEMO Actuator

    2003-08-07

    SAMA is a multichannel, arbitrary waveform generator program for driving microelectromechanical systems (MEMS). It allows the user to piece together twelve available wave parts, thereby permitting the user to create practically any waveform, or upload a previously constructed signal. The waveforms (bundled together as a signal) may simultaneously be output through four different channels to actuate MEMS devices, and the number of output channels may be increased depending on the DAQ card or instrument utilized.more » Additionally, real-time changes may be made to the frequency and amplitude. The signal may be paused temporarily. The waveform may be saved to file for future uploading. Recent work for this version has focused on modifications that will allow loading previously generated arbitrary waveforms, independent channel waveform amplification, adding a pause function, separating the "modify waveform: and "end program" functions, and simplifying the user interface by adding test blocks with statements to help the user program and output the desired signals. The program was developed in an effort to alleviate some of the limitations of Micro Driver. For example, Micro Driver will not allow the user to select a segment of a sine wave, but rather the user is limited to choosing either a whole or half sine wave pattern. It therefore becomes quite difficult ot construct partial sine wave patterns out of a "ramp" waveparts for several reasons. First, one must determine on paper how many data points each ramp will cover, and what the slopes of these ramps will be. Second, from what was observed, Micro Driver has difficulty processing more than six distinct waveparts during sequencing. The program will allow the user to input the various waves into the desired sequence; however, it will not allow the user to compile them (by clicking "ok" and returning to the main screen). Third, should the user decide that they want to increase the amplitute of the output signal

  4. Sandia's Arbitrary Waveform MEMO Actuator

    SciTech Connect

    Brian Sosnowchik, Mark Jenkins

    2003-08-07

    SAMA is a multichannel, arbitrary waveform generator program for driving microelectromechanical systems (MEMS). It allows the user to piece together twelve available wave parts, thereby permitting the user to create practically any waveform, or upload a previously constructed signal. The waveforms (bundled together as a signal) may simultaneously be output through four different channels to actuate MEMS devices, and the number of output channels may be increased depending on the DAQ card or instrument utilized. Additionally, real-time changes may be made to the frequency and amplitude. The signal may be paused temporarily. The waveform may be saved to file for future uploading. Recent work for this version has focused on modifications that will allow loading previously generated arbitrary waveforms, independent channel waveform amplification, adding a pause function, separating the "modify waveform: and "end program" functions, and simplifying the user interface by adding test blocks with statements to help the user program and output the desired signals. The program was developed in an effort to alleviate some of the limitations of Micro Driver. For example, Micro Driver will not allow the user to select a segment of a sine wave, but rather the user is limited to choosing either a whole or half sine wave pattern. It therefore becomes quite difficult ot construct partial sine wave patterns out of a "ramp" waveparts for several reasons. First, one must determine on paper how many data points each ramp will cover, and what the slopes of these ramps will be. Second, from what was observed, Micro Driver has difficulty processing more than six distinct waveparts during sequencing. The program will allow the user to input the various waves into the desired sequence; however, it will not allow the user to compile them (by clicking "ok" and returning to the main screen). Third, should the user decide that they want to increase the amplitute of the output signal, they must

  5. Evolution of nonlinear ion-acoustic solitary wave propagation in rotating plasma

    SciTech Connect

    Das, G. C.; Nag, Apratim

    2006-08-15

    A simple unmagnetized plasma rotating around an axis at an angle {theta} with the propagation direction of the acoustic mode has been taken. The nonlinear wave mode has been derived as an equivalent Sagdeev potential equation. A special procedure, known as the tanh method, has been developed to study the nonlinear wave propagation in plasma dynamics. Further, under small amplitude approximation, the nonlinear plasma acoustic mode has been exploited to study the evolution of soliton propagation in the plasma. The main emphasis has been given to the interaction of Coriolis force on the changes of coherent structure of the soliton. The solitary wave solution finds the different nature of solitons called compressive and rarefactive solitons as well as its explosions or collapses along with soliton dynamics and these have been showing exciting observations in exhibiting a narrow wave packet with the generation of high electric pressure and the growth of high energy which, in turn, yields the phenomena of radiating soliton in dynamics.

  6. Large amplitude solitary waves in a warm magnetoplasma with kappa distributed electrons

    SciTech Connect

    El-Tantawy, S. A.; El-Bedwehy, N. A.; Abd El-Razek, H. N.; Mahmood, S.

    2013-02-15

    The large amplitude nonlinear ion acoustic solitary wave propagating obliquely to an external magnetic field in a magnetized plasma with kappa distributed electrons and warm ions is investigated through deriving energy-balance-like expression involving a Sagdeev potential. Analytical and numerical calculations of the values of Mach number reveal that both of subsonic and supersonic electrostatic solitary structures can exist in this system. The influence on the soliton characteristics of relevant physical parameters such as the Mach number, the superthermal parameter, the directional cosine, the ratio of ion-to-electron temperature, and the ion gyrofrequency has been investigated.

  7. Action of an electromagnetic pulse on a plasma with a high level of ion-acoustic turbulence. Field diffusion and subdiffusion

    SciTech Connect

    Ovchinnikov, K. N.; Uryupin, S. A.

    2013-09-15

    Specific features of the interaction of a relatively weak electromagnetic pulse with a nonisothermal current-carrying plasma in which the electron drift velocity is much higher than the ion-acoustic velocity, but lower than the electron thermal velocity, are studied. If the state of the plasma with ion-acoustic turbulence does not change during the pulse action, the field penetrates into the plasma in the ordinary diffusion regime, but the diffusion coefficient in this case is inversely proportional to the anomalous conductivity. If, during the pulse action, the particle temperatures and the current-driving field change due to turbulent heating, the field penetrates into the plasma in the subdiffusion regime. It is shown how the presence of subdiffusion can be detected by measuring the reflected field.

  8. Dust-ion-acoustic double layers in multi-ion dusty plasma

    SciTech Connect

    Mamun, A. A.; Deeba, F.

    2015-08-15

    A theoretical investigation has been made on nonplanar (cylindrical and spherical) dust-ionacoustic (DIA) double layers (DLs) in a multi-ion dusty plasma system containing inertial positive and negative ions and arbitrarily charged stationary dust. The dust particles have been considered as arbitrarily (either positively or negatively) charged in order to observe the effects of the dust polarity on the DIA DLs. The ion species were considered to be at different temperatures to observe the effects of the temperatures on that waves. The modified Gardner equation, which has been derived by employing the reductive perturbation method, has been used to analyze time-dependent nonplanar and planar DIA DLs. It has been found that the time evolution of DIA DLs is significantly modified not only by the nonplanar geometry, but also by the polarity, temperature, and mass ratio of the constituent particles. It has been also found that the amplitude of cylindrical DIA DL structures is larger than that of 1D planar ones, but smaller than that of the spherical ones.

  9. Effects of superthermal electrons and negatively (positively) charged dust grains on dust-ion acoustic wave modulation

    NASA Astrophysics Data System (ADS)

    Ainejad, H.; Mahdavi, M.; Shahmansouri, M.

    2014-05-01

    The modulational instability of dust-ion acoustic (DIA) waves is studied in an unmagnetized dusty plasma comprising arbitrarily charged dust particles, adiabatic fluid ions, and electrons satisfying a kappa ( κ) distribution. By using the multiple space and time scales perturbation, a nonlinear Schrödinger (NLS) equation is derived, and then the existence along with the stability of wave packets are discussed in the parameter space of two oppositely charged dust and ion temperature over a range of values of electron superthermality. It is found that the transition from stable dark solitons to unstable bright ones shifts to the smaller wavelength regions in a way that depends on the increase of superthermality index κ. In this case, a narrower range (in spatial extension) of the envelope solitons is observed. It is also found that the instability growth rate reduces, due to the electron superthemality. Furthermore, positive dust concentration enhances the instability region, whereas more populations of negative dust grains may control or suppress one.

  10. Ion-acoustic Gardner Solitons in electron-positron-ion plasma with two-electron temperature distributions

    NASA Astrophysics Data System (ADS)

    Rehman, Momin A.; Mishra, M. K.

    2016-01-01

    The ion-acoustic solitons in collisionless plasma consisting of warm adiabatic ions, isothermal positrons, and two temperature distribution of electrons have been studied. Using reductive perturbation method, Korteweg-de Vries (K-dV), the modified K-dV (m-KdV), and Gardner equations are derived for the system. The soliton solution of the Gardner equation is discussed in detail. It is found that for a given set of parameter values, there exists a critical value of β=Tc/Th, (ratio of cold to hot electron temperature) below which only rarefactive KdV solitons exist and above it compressive KdV solitons exist. At the critical value of β, both compressive and rarefactive m-KdV solitons co-exist. We have also investigated the soliton in the parametric regime where the KdV equation is not valid to study soliton solution. In this region, it is found that below the critical concentration the system supports rarefactive Gardner solitons and above it compressive Gardner solitons are found. The effects of temperature ratio of two-electron species, cold electron concentration, positron concentration on the characteristics of solitons are also discussed.

  11. Modeling solar flare conduction fronts. I - Homogeneous plasmas and ion-acoustic turbulence. II - Inhomogeneous plasmas and ambipolar electric fields

    NASA Technical Reports Server (NTRS)

    Mckean, M. E.; Winglee, R. M.; Dulk, G. A.

    1990-01-01

    A one-dimensional, electrostatic, particle-in-cell simulation is used here to model the expansion of a heated electron population in a coronal loop during a solar flare and the characteristics of the associated X-ray emissions. The hot electrons expand outward from the localized region, creating an ambipolar electric field which accelerates a return current of cooler, ambient electrons. Ion-acoustic waves are generated by the return currents as proposed by Brown et al. (1979), but they play little or no role in containing energetic electrons and the conduction front proposed by Brown et al. does not form. The X-ray emission efficiency of the electrons is too low in the corona for them to be the source of hard X-ray bursts. The particle dynamics changes dramatically if the heated plasma is at low altitudes and expands upward into the more tenuous plasma at higher altitudes. Two important applications of this finding are the radio-frequency heating of the corona and the collisional heating of the chromosphere by precipitating energetic electrons. In both cases, the overlying plasma has a density that is too low to supply a balancing return current to the expanding hot electrons. As a result, an ambipolar electric field develops that tends to confine the energetic electrons behind a front that propagate outward at about the speed of sound.

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

    NASA Astrophysics Data System (ADS)

    Hafez, M. G.; Roy, N. C.; Talukder, M. R.; Hossain Ali, M.

    2016-09-01

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

  13. Effect of dust charge fluctuation on the propagation of dust-ion acoustic waves in inhomogeneous mesospheric dusty plasma

    SciTech Connect

    Mowafy, A. E.; El-Shewy, E. K.; Zahran, M. A.; Moslem, W. M.

    2008-07-15

    Investigation of positive and negative dust charge fluctuations on the propagation of dust-ion acoustic waves (DIAWs) in a weakly inhomogeneous, collisionless, unmagnetized dusty plasmas consisting of cold positive ions, stationary positively and negatively charged dust particles and isothermal electrons. The reductive perturbation method is employed to reduce the basic set of fluid equations to the variable coefficients Korteweg-de Varies (KdV) equation. At the critical ion density, the KdV equation is not appropriate for describing the system. Hence, a new set of stretched coordinates is considered to derive the modified variable coefficients KdV equation. It is found that the presence of positively charged dust grains does not only significantly modify the basic properties of solitary structure, but also changes the polarity of the solitary profiles. In the vicinity of the critical ion density, neither KdV nor the modified KdV equation is appropriate for describing the DIAWs. Therefore, a further modified KdV equation is derived, which admits both soliton and double layer solutions.

  14. Planar and non-planar dust ion-acoustic solitary waves in a quantum dusty electronegative plasma

    NASA Astrophysics Data System (ADS)

    Tasnim, S.; Islam, S.; Mamun, A. A.

    2012-03-01

    A theoretical investigation has been made on nonlinear propagation of planar and non-planar solitary waves in a quantum dusty electronegative plasma, whose constituents are quantum electrons, positive ions, negative ions, and arbitrarily charged stationary dust. The reductive perturbation method has been used to derive the Korteweg-de Vries and modified Korteweg-de Vries equations for studying the basic features of solitary waves, which are associated with both positive and negative ion dynamics. The effects of quantum parameter (H), positive and negative ion mass ratio (μin), as well as dust and positive ion number densities (β) on the basic features (polarity, height, and width) of planar solitary waves have been studied. It has been also found that the properties of dust ion-acoustic solitary waves in non-planar cylindrical or spherical geometry differ from those in planar one-dimensional geometry. The implications of our results in space (viz., interstellar compact objects like neutron stars) and laboratory experiments (e.g., intense laser solid density plasma experiments) have been briefly discussed.

  15. Warm wavebreaking of nonlinear plasma waves with arbitrary phasevelocities

    SciTech Connect

    Schroeder, C.B.; Esarey, E.; Shadwick, B.A.

    2004-11-12

    A warm, relativistic fluid theory of a nonequilibrium, collisionless plasma is developed to analyze nonlinear plasma waves excited by intense drive beams. The maximum amplitude and wavelength are calculated for nonrelativistic plasma temperatures and arbitrary plasma wave phase velocities. The maximum amplitude is shown to increase in the presence of a laser field. These results set a limit to the achievable gradient in plasma-based accelerators.

  16. How arbitrary is language?

    PubMed Central

    Monaghan, Padraic; Shillcock, Richard C.; Christiansen, Morten H.; Kirby, Simon

    2014-01-01

    It is a long established convention that the relationship between sounds and meanings of words is essentially arbitrary—typically the sound of a word gives no hint of its meaning. However, there are numerous reported instances of systematic sound–meaning mappings in language, and this systematicity has been claimed to be important for early language development. In a large-scale corpus analysis of English, we show that sound–meaning mappings are more systematic than would be expected by chance. Furthermore, this systematicity is more pronounced for words involved in the early stages of language acquisition and reduces in later vocabulary development. We propose that the vocabulary is structured to enable systematicity in early language learning to promote language acquisition, while also incorporating arbitrariness for later language in order to facilitate communicative expressivity and efficiency. PMID:25092667

  17. Current-driven ion-acoustic and potential-relaxation instabilities excited in plasma plume during electron beam welding

    SciTech Connect

    Trushnikov, D. N.; Mladenov, G. M. Koleva, E. G.; Belenkiy, V. Ya. Varushkin, S. V.

    2014-04-15

    Many papers have sought correlations between the parameters of secondary particles generated above the beam/work piece interaction zone, dynamics of processes in the keyhole, and technological processes. Low- and high-frequency oscillations of the current, collected by plasma have been observed above the welding zone during electron beam welding. Low-frequency oscillations of secondary signals are related to capillary instabilities of the keyhole, however; the physical mechanisms responsible for the high-frequency oscillations (>10 kHz) of the collected current are not fully understood. This paper shows that peak frequencies in the spectra of the collected high-frequency signal are dependent on the reciprocal distance between the welding zone and collector electrode. From the relationship between current harmonics frequency and distance of the collector/welding zone, it can be estimated that the draft velocity of electrons or phase velocity of excited waves is about 1600 m/s. The dispersion relation with the properties of ion-acoustic waves is related to electron temperature 10 000 K, ion temperature 2 400 K and plasma density 10{sup 16} m{sup −3}, which is analogues to the parameters of potential-relaxation instabilities, observed in similar conditions. The estimated critical density of the transported current for creating the anomalous resistance state of plasma is of the order of 3 A·m{sup −2}, i.e. 8 mA for a 3–10 cm{sup 2} collector electrode. Thus, it is assumed that the observed high-frequency oscillations of the current collected by the positive collector electrode are caused by relaxation processes in the plasma plume above the welding zone, and not a direct demonstration of oscillations in the keyhole.

  18. Arbitrary waveform generator

    NASA Astrophysics Data System (ADS)

    Blackmon, Fletcher A.

    1992-04-01

    It is a general purpose and object of the present invention to provide an arbitrary waveform generator. It is a further object that the generator has the ability to produce both pulse waveforms and continuous waveforms. Other objects are that the generator be compact and only require low power for lending itself to battery powered operation. These objects are accomplished with the present invention by providing a system in which digital waveforms are created using a software package such as DADiSP. The software package forms signals that are then transferred to an EPROM. Each signal type occupies a certain block of address space within the EPROM. A great number of signals may be digitally stored in this way. The operator then constructs simple microprocessor computer codes to access any signal, any combination of signals, or all signals to form a unique waveform generation sequence. Therefore the operator selects arbitrarily which of the previously stored signals to generate. Key features include the EPROM storing a single pulse for pulse waveforms and a single period of waveform for continuous waveforms. Other key features are the ability to control the sequence of generation, the number of times each signal is generated, the time between pulses, and the time between the generation of different signal types. These features are controlled by the microprocessor codes residing in a microprocessor.

  19. Spectral methods on arbitrary grids

    NASA Technical Reports Server (NTRS)

    Carpenter, Mark H.; Gottlieb, David

    1995-01-01

    Stable and spectrally accurate numerical methods are constructed on arbitrary grids for partial differential equations. These new methods are equivalent to conventional spectral methods but do not rely on specific grid distributions. Specifically, we show how to implement Legendre Galerkin, Legendre collocation, and Laguerre Galerkin methodology on arbitrary grids.

  20. Numerical study of the two-species Vlasov-Ampère system: Energy-conserving schemes and the current-driven ion-acoustic instability

    NASA Astrophysics Data System (ADS)

    Cheng, Yingda; Christlieb, Andrew J.; Zhong, Xinghui

    2015-05-01

    In this paper, we propose energy-conserving Eulerian solvers for the two-species Vlasov-Ampère (VA) system and apply the methods to simulate current-driven ion-acoustic instability. The two-species VA systems are of practical importance in applications, and they conserve many physical quantities including the particle number of each species and the total energy that is comprised of kinetic energy for both species and the electric energy. The main goal of this paper is to generalize our previous work for the single-species VA system [9] and Vlasov-Maxwell (VM) system [8] to the two-species case. The methodologies proposed involve careful design of temporal discretization and the use of the discontinuous Galerkin (DG) spatial discretizations. We show that the energy-conserving time discretizations for single-species equations [9,8] can also work for the two-species case if extended properly. Compared to other high order schemes, we emphasize that our schemes can preserve the total particle number and total energy on the fully discrete level regardless of mesh size, making them very attractive for long time simulations. We benchmark our algorithms on a test example to check the one-species limit, and the current-driven ion-acoustic instability. To simulate the current-driven ion-acoustic instability, a slight modification for the implicit method is necessary to fully decouple the split equations. This is achieved by a Gauss-Seidel type iteration technique. Numerical results verified the conservation and performance of our methods. Finally, we remark that the schemes in this paper can be readily extended to applications when the models take more general form, such as the multi-species VM equations.

  1. Amplitude dynamics favors synchronization in complex networks

    NASA Astrophysics Data System (ADS)

    Gambuzza, Lucia Valentina; Gómez-Gardeñes, Jesus; Frasca, Mattia

    2016-04-01

    In this paper we study phase synchronization in random complex networks of coupled periodic oscillators. In particular, we show that, when amplitude dynamics is not negligible, phase synchronization may be enhanced. To illustrate this, we compare the behavior of heterogeneous units with both amplitude and phase dynamics and pure (Kuramoto) phase oscillators. We find that in small network motifs the behavior crucially depends on the topology and on the node frequency distribution. Surprisingly, the microscopic structures for which the amplitude dynamics improves synchronization are those that are statistically more abundant in random complex networks. Thus, amplitude dynamics leads to a general lowering of the synchronization threshold in arbitrary random topologies. Finally, we show that this synchronization enhancement is generic of oscillators close to Hopf bifurcations. To this aim we consider coupled FitzHugh-Nagumo units modeling neuron dynamics.

  2. Amplitude dynamics favors synchronization in complex networks

    PubMed Central

    Gambuzza, Lucia Valentina; Gómez-Gardeñes, Jesus; Frasca, Mattia

    2016-01-01

    In this paper we study phase synchronization in random complex networks of coupled periodic oscillators. In particular, we show that, when amplitude dynamics is not negligible, phase synchronization may be enhanced. To illustrate this, we compare the behavior of heterogeneous units with both amplitude and phase dynamics and pure (Kuramoto) phase oscillators. We find that in small network motifs the behavior crucially depends on the topology and on the node frequency distribution. Surprisingly, the microscopic structures for which the amplitude dynamics improves synchronization are those that are statistically more abundant in random complex networks. Thus, amplitude dynamics leads to a general lowering of the synchronization threshold in arbitrary random topologies. Finally, we show that this synchronization enhancement is generic of oscillators close to Hopf bifurcations. To this aim we consider coupled FitzHugh-Nagumo units modeling neuron dynamics. PMID:27108847

  3. Bifurcations of nonlinear ion acoustic travelling waves in the frame of a Zakharov-Kuznetsov equation in magnetized plasma with a kappa distributed electron

    SciTech Connect

    Kumar Samanta, Utpal; Saha, Asit; Chatterjee, Prasanta

    2013-05-15

    Bifurcations of nonlinear propagation of ion acoustic waves (IAWs) in a magnetized plasma whose constituents are cold ions and kappa distributed electron are investigated using a two component plasma model. The standard reductive perturbation technique is used to derive the Zakharov-Kuznetsov (ZK) equation for IAWs. By using the bifurcation theory of planar dynamical systems to this ZK equation, the existence of solitary wave solutions and periodic travelling wave solutions is established. All exact explicit solutions of these travelling waves are determined. The results may have relevance in dense space plasmas.

  4. The effect of trapped electrons on the three-dimensional ion-acoustic shock wave in magnetized ionic-pair plasma

    NASA Astrophysics Data System (ADS)

    Guo, Shimin; Mei, Liquan; He, Ya-Ling; Guo, Huaqi; Zhao, Yanjun

    2016-04-01

    The effect of trapped electrons featuring vortex-like distribution on the nonlinear behavior of a three-dimensional ion-acoustic shock wave is investigated in a magnetized ionic-pair plasma. In the long-wave approximation, the dynamics of the shock wave is governed by the (3{+}1) -dimensional Schamel-Zakharov-Kuznetsov-Burgers' equation due to the presence of trapped electrons and ion kinematic viscosity. By using the homogeneous balance principle and tanh function method, we obtain a novel exact shock wave solution of the equation. It is found for the first time that the trapped electrons can support a shock wave with only positive polarity.

  5. Nonlinear Excitation of Acoustic Modes by Large-Amplitude Alfvén Waves in a Laboratory Plasma

    NASA Astrophysics Data System (ADS)

    Dorfman, S.; Carter, T. A.

    2013-05-01

    The nonlinear three-wave interaction process at the heart of the parametric decay process is studied by launching counterpropagating Alfvén waves from antennas placed at either end of the Large Plasma Device. A resonance in the beat wave response produced by the two launched Alfvén waves is observed and is identified as a damped ion acoustic mode based on the measured dispersion relation. Other properties of the interaction including the spatial profile of the beat mode and response amplitude are also consistent with theoretical predictions for a three-wave interaction driven by a nonlinear ponderomotive force.

  6. On the generation of large amplitude spiky solitons by ultralow frequency earthquake emission in the Van Allen radiation belt

    SciTech Connect

    Mofiz, U. A.

    2006-08-15

    The parametric coupling between earthquake emitted circularly polarized electromagnetic radiation and ponderomotively driven ion-acoustic perturbations in the Van Allen radiation belt is considered. A cubic nonlinear Schroedinger equation for the modulated radiation envelope is derived, and then solved analytically. For ultralow frequency earthquake emissions large amplitude spiky supersonic bright solitons or subsonic dark solitons are found to be generated in the Van Allen radiation belt, detection of which can be a tool for the prediction of a massive earthquake may be followed later.

  7. Automatic generation of tree level helicity amplitudes

    NASA Astrophysics Data System (ADS)

    Stelzer, T.; Long, W. F.

    1994-11-01

    The program MadGraph is presented which automatically generates postscript Feynman diagrams and Fortran code to calculate arbitrary tree level helicity amplitudes by calling HELAS[1] subroutines. The program is written in Fortran and is available in Unix and VMS versions. MadGraph currently includes standard model interactions of QCD and QFD, but is easily modified to include additional models such as supersymmetry.

  8. Automatic generation of tree level helicity amplitudes

    NASA Astrophysics Data System (ADS)

    Stelzer, T.; Long, W. F.

    1994-07-01

    The program MadGraph is presented which automatically generates postscript Feynman diagrams and Fortran code to calculate arbitrary tree level helicity amplitudes by calling HELAS[1] subroutines. The program is written in Fortran and is available in Unix and VMS versions. MadGraph currently includes standard model interactions of QCD and QFD, but is easily modified to include additional models such as supersymmetry.

  9. A Simple Arbitrary Solid Slicer

    SciTech Connect

    Yao, J

    2005-06-23

    The intersection of a given plane and an arbitrary (possibly non-convex, with multiple connectivities) meshed solid is exactly expressed by a set of planar cross-sections. A rule for marching on the edges of an arbitrary polyhedron is set for obtaining the topology of the cross-section. The method neither seeks triangulation of the surface mesh nor utilizes look-up tables, therefore it has optimal efficiency.

  10. The roles of non-extensivity and dust concentration as bifurcation parameters in dust-ion acoustic traveling waves in magnetized dusty plasma

    SciTech Connect

    Narayan Ghosh, Uday; Kumar Mandal, Pankaj Chatterjee, Prasanta

    2014-03-15

    Dust ion-acoustic traveling waves are studied in a magnetized dusty plasma in presence of static dust and non-extensive distributed electrons in the framework of Zakharov-Kuznesstov-Burgers (ZKB) equation. System of coupled nonlinear ordinary differential equations is derived from ZKB equation, and equilibrium points are obtained. Nonlinear wave phenomena are studied numerically using fourth order Runge-Kutta method. The change from unstable to stable solution and consequently to asymptotic stable of dust ion acoustic traveling waves is studied through dynamical system approach. It is found that some dramatical features emerge when the non-extensive parameter and the dust concentration parameters are varied. Behavior of the solution of the system changes from unstable to stable and stable to asymptotic stable depending on the value of the non-extensive parameter. It is also observed that when the dust concentration is increased the solution pattern is changed from oscillatory shocks to periodic solution. Thus, non-extensive and dust concentration parameters play crucial roles in determining the nature of the stability behavior of the system. Thus, the non-extensive parameter and the dust concentration parameters can be treated as bifurcation parameters.

  11. Effect of ion and ion-beam mass ratio on the formation of ion-acoustic solitons in magnetized plasma in the presence of electron inertia

    SciTech Connect

    Kalita, B. C.; Barman, S. N.

    2009-05-15

    The propagation of ion-acoustic solitary waves in magnetized plasma with cold ions and ion-beams together with electron inertia has been investigated theoretically through the Korteweg-de Vries equation. Subject to the drift velocity of the ion beam, the existence of compressive solitons is found to become extinct as {alpha} (=cold ion mass/ion-beam mass) tends to 0.01 when {gamma}=0.985 ({gamma} is the beam velocity/phase velocity). Interestingly, a transitional direction of propagation of solitary waves has been unearthed for change over, from compressive solitons to rarefactive solitons based on {alpha} and {sigma}{sub {upsilon}}(=cosine of the angle {theta} made by the wave propagation direction {xi} with the direction of the magnetic field) for fixed Q(=electron mass/ion mass). Further, the direction of propagation of ion-acoustic waves is found to be the deterministic factor to admit compressive or rarefactive solitons subject to beam outsource.

  12. Non-planar ion-acoustic solitary waves and their head-on collision in a plasma with nonthermal electrons and warm adiabatic ions

    SciTech Connect

    Han Jiuning; He Yonglin; Chen Yan; Zhang Kezhi; Ma Baohong

    2013-01-15

    By using the model of Cairns et al.[Geophys. Rev. Lett. 22, 2709 (1995)], the head-on collision of cylindrical/spherical ion-acoustic solitary waves in an unmagnetized non-planar plasma consisting of warm adiabatic ions and nonthermally distributed electrons is investigated. The extended Poincare-Lighthill-Kuo perturbation method is used to derive the modified Korteweg-de Vries equations for ion-acoustic solitary waves in this plasma system. The effects of the plasma geometry m, the ion to electron temperature ratio {sigma}, and the nonthermality of the electron distribution {alpha} on the interaction of the colliding solitary waves are studied. It is found that the plasma geometries have a big impact on the phase shifts of solitary waves. Also it is important to note that the phase shifts induced by the collision of compressive and rarefactive solitary waves are very different. We point out that this study is useful to the investigations about the observations of electrostatic solitary structures in astrophysical as well as in experimental plasmas with nonthermal energetic electrons.

  13. Obliquely propagating ion acoustic waves in the auroral E region: Further evidence of irregularity production by field-aligned electron streaming

    SciTech Connect

    Villain, J.P. ); Hanuise, C. ); Greenwald, R.A.; Baker, K.B.; Ruohoniemi, J.M. )

    1990-06-01

    Common volume observations of E region high-latitude irregularities at decameter wavelengths have been obtained with the JHU/APL HF radar located at Goose Bay, Labrador, and the SHERPA HF radar located at Schefferville, Quebec. In this paper, the authors analyze an event with characteristics similar to those of a distinctive type of event described by Villain et al. (1987). The experimental configuration, which combines the azimuthal-scanning capability of the Goose Bay radar with the frequency-scanning operation of the Schefferville radar, has provided unambiguous evidence of the existence of two irregularity layers at different altitudes within the E region. The layers, which exhibit different characteristics, can be related to the action of the gradient drift and ion acoustic instability mechanisms. It is shown that the ion acoustic modes have phase velocities in the range of 400 to 550 m/s and are produced in regions of subcritical perpendicular electron Hall drift. They infer that the observed irregularities are produced through a combination of perpendicular and field-aligned relative electron-ion drifts. Features previously observed but no t satisfactorily explained by perpendicular drift excitation alone can be understood in terms of field-aligned drift excitation. They conclude that the role of electron-ion field-aligned drift may be much more important than previously realized.

  14. Recurrence relations of Kummer functions and Regge string scattering amplitudes

    NASA Astrophysics Data System (ADS)

    Lee, Jen-Chi; Mitsuka, Yoshihiro

    2013-04-01

    We discover an infinite number of recurrence relations among Regge string scattering amplitudes [11, 30] of different string states at arbitrary mass levels in the open bosonic string theory. As a result, all Regge string scattering amplitudes can be algebraically solved up to multiplicative factors. Instead of decoupling zero-norm states in the fixed angle regime, the calculation is based on recurrence relations and addition theorem of Kummer functions of the second kind. These recurrence relations among Regge string scattering amplitudes are dual to linear relations or symmetries among high-energy fixed angle string scattering amplitudes discovered previously.

  15. Mode coupling evolution in arbitrary inflationary backgrounds

    SciTech Connect

    Bernardeau, Francis

    2011-02-01

    The evolution of high order correlation functions of a test scalar field in arbitrary inflationary backgrounds is computed. Whenever possible, exact results are derived from quantum field theory calculations. Taking advantage of the fact that such calculations can be mapped, for super-horizon scales, into those of a classical system, we express the expected correlation functions in terms of classical quantities, power spectra, Green functions, that can be easily computed in the long-wavelength limit. Explicit results are presented that extend those already known for a de Sitter background. In particular the expressions of the late time amplitude of bispectrum and trispectrum, as well as the whole high-order correlation structure, are given in terms of the expansion factor behavior. When compared to the case of a de Sitter background, power law inflation and chaotic inflation induced by a massive field are found to induce high order correlation functions the amplitudes of which are amplified by almost one order of magnitude. These results indicate that the dependence of the related non-Gaussian parameters — such as f{sub NL} — on the wave-modes is at percent level.

  16. Three-point disc amplitudes in the RNS formalism

    NASA Astrophysics Data System (ADS)

    Becker, Katrin; Becker, Melanie; Robbins, Daniel; Su, Ning

    2016-06-01

    We calculate all tree level string theory vacuum to Dp-brane disc amplitudes involving an arbitrary RR-state and two NS-NS vertex operators. This computation was earlier performed by K. Becker, Guo, and Robbins for the simplest case of a RR-state of type C (p - 3). Here we use the aid of a computer to calculate all possible three-point amplitudes involving a RR-vertex operator of type C (p + 1 + 2 k).

  17. Calculating scattering amplitudes efficiently

    SciTech Connect

    Dixon, L.

    1996-01-01

    We review techniques for more efficient computation of perturbative scattering amplitudes in gauge theory, in particular tree and one- loop multi-parton amplitudes in QCD. We emphasize the advantages of (1) using color and helicity information to decompose amplitudes into smaller gauge-invariant pieces, and (2) exploiting the analytic properties of these pieces, namely their cuts and poles. Other useful tools include recursion relations, special gauges and supersymmetric rearrangements. 46 refs., 11 figs.

  18. CONTROLLING THE CHARACTERISTICS OF LASER LIGHT: Relaxation oscillations in solid-state ring lasers with arbitrary mode polarizations

    NASA Astrophysics Data System (ADS)

    Naniĭ, O. E.; Paleev, M. R.

    1993-07-01

    An expression is derived for the frequency of relaxation oscillations of a solid-state ring laser for arbitrary polarizations of the radiation, for an arbitrary feedback parameter, and for a cavity with amplitude and frequency nonreciprocity. The analysis is also applicable to linear double-mode and two-channel solid-state lasers.

  19. Comment on ``The effects of Bohm potential on ion-acoustic solitary waves interaction in a nonplanar quantum plasma'' [Phys. Plasmas 17, 082307 (2010)

    NASA Astrophysics Data System (ADS)

    Akbari-Moghanjoughi, M.

    2010-11-01

    Recently, Li [Phys. Plasmas 17, 082307 (2010)] has studied the effects of Bohm potential on interaction of nonplanar ion-acoustic solitary waves in an unmagnetized electron-positron-ion quantum plasma. In his work the extended reductive perturbation technique has been employed to reduce the basic quantum hydrodynamics plasma equations to Korteweg-de Vries evolution equations (one for each wave) as well as other coupled differential equations describing the phase variation of the resulting solitary waves. The calculated collisional phase-shifts are then numerically evaluated in terms of plasma parameters such as the fractional positron to ion number-density p, relative electron to positron Fermi-temperature σ and the quantum diffraction parameter H. We show that in the chosen plasma model, the parameters p and σ are not independent quantum plasma parameters which has important consequences on the graphical interpretations presented in the mentioned article.

  20. Comment on 'The effects of Bohm potential on ion-acoustic solitary waves interaction in a nonplanar quantum plasma' [Phys. Plasmas 17, 082307 (2010)

    SciTech Connect

    Akbari-Moghanjoughi, M.

    2010-11-15

    Recently, Li [Phys. Plasmas 17, 082307 (2010)] has studied the effects of Bohm potential on interaction of nonplanar ion-acoustic solitary waves in an unmagnetized electron-positron-ion quantum plasma. In his work the extended reductive perturbation technique has been employed to reduce the basic quantum hydrodynamics plasma equations to Korteweg-de Vries evolution equations (one for each wave) as well as other coupled differential equations describing the phase variation of the resulting solitary waves. The calculated collisional phase-shifts are then numerically evaluated in terms of plasma parameters such as the fractional positron to ion number-density p, relative electron to positron Fermi-temperature {sigma} and the quantum diffraction parameter H. We show that in the chosen plasma model, the parameters p and {sigma} are not independent quantum plasma parameters which has important consequences on the graphical interpretations presented in the mentioned article.

  1. Time-fractional Schamel-KdV equation for dust-ion-acoustic waves in pair-ion plasma with trapped electrons and opposite polarity dust grains

    NASA Astrophysics Data System (ADS)

    Guo, Shimin; Mei, Liquan; He, Yaling; Li, Yibao

    2016-03-01

    Nonlinear propagation of dust-ion-acoustic (DIA) waves is investigated in a one-dimensional, unmagnetized plasma containing positive ions, negative ions, trapped electrons featuring vortex-like distribution, and immobile dust grains having both positive and negative charges. Via reductive perturbation method, Agrawal's method, and Euler-Lagrange equation, the time-fractional Schamel-KdV equation under the sense of Riesz fractional derivative is derived to describe nonlinear behavior of DIA waves. The approximate solution of the time-fractional Schamel-KdV equation is constructed in terms of Jacobi elliptic functions by variational iteration method. The effect of the plasma parameters on the DIA solitary waves is also discussed in detail.

  2. Representing Arbitrary Boosts for Undergraduates.

    ERIC Educational Resources Information Center

    Frahm, Charles P.

    1979-01-01

    Presented is a derivation for the matrix representation of an arbitrary boost, a Lorentz transformation without rotation, suitable for undergraduate students with modest backgrounds in mathematics and relativity. The derivation uses standard vector and matrix techniques along with the well-known form for a special Lorentz transformation. (BT)

  3. A damped simple pendulum of constant amplitude

    NASA Astrophysics Data System (ADS)

    Abdelkader, Mostafa A.

    1984-03-01

    A simple pendulum acted on by gravity and subjected to a resistance proportional to the velocity of the bob is considered. If the length of the string and the mass of the bob are held constant, the amplitude of the bob decreases gradually because of the damping. We want to keep the maximum swing of the bob constant for all time; this we achieve by varying the length of the string, the mass of the bob or both. The key to the solution of our problem is a second-order nonlinear differential equation having arbitrary nonlinearity and an arbitrary coefficient function, for which we give the exact integral. We also give an application of this differential equation to a boundary-value problem for a nonlinear generalization of a hypergeometric equation.

  4. Arbitrary bending plasmonic light waves.

    PubMed

    Epstein, Itai; Arie, Ady

    2014-01-17

    We demonstrate the generation of self-accelerating surface plasmon beams along arbitrary caustic curvatures. These plasmonic beams are excited by free-space beams through a two-dimensional binary plasmonic phase mask, which provides the missing momentum between the two beams in the direction of propagation and sets the required phase for the plasmonic beam in the transverse direction. We examine the cases of paraxial and nonparaxial curvatures and show that this highly versatile scheme can be designed to produce arbitrary plasmonic self-accelerating beams. Several different plasmonic beams, which accelerate along polynomial and exponential trajectories, are demonstrated both numerically and experimentally, with a direct measurement of the plasmonic light intensity using a near-field scanning optical microscope.

  5. Axial anomaly at arbitrary virtualities

    SciTech Connect

    Veretin, O.L.; Teryaev, O.V.

    1995-12-01

    The one-loop analytic expression for the axial-vector triangle diagram involving an anomaly is obtained for arbitrary virtualities of external momenta. The `t Hooft consistency principle is applied to the QCD sum rules for the first moment of the photon spin structure function g{sub l}{sup {gamma}}. It is shown that the contribution of the singlet axial current to the sum rules for g{sub l}{sup {gamma}} vanishes. 19 refs., 1 fig.

  6. PULSE AMPLITUDE ANALYZER

    DOEpatents

    Greenblatt, M.H.

    1958-03-25

    This patent pertains to pulse amplitude analyzers for sorting and counting a serles of pulses, and specifically discloses an analyzer which ls simple in construction and presents the puise height distribution visually on an oscilloscope screen. According to the invention, the pulses are applied to the vertical deflection plates of an oscilloscope and trigger the horizontal sweep. Each pulse starts at the same point on the screen and has a maximum amplitude substantially along the same vertical line. A mask is placed over the screen except for a slot running along the line where the maximum amplitudes of the pulses appear. After the slot has been scanned by a photocell in combination with a slotted rotating disk, the photocell signal is displayed on an auxiliary oscilloscope as vertical deflection along a horizontal time base to portray the pulse amplitude distribution.

  7. PULSE AMPLITUDE ANALYSERS

    DOEpatents

    Lewis, I.A.D.

    1956-05-15

    This patent pentains to an electrical pulse amplitude analyzer, capable of accepting input pulses having a separation between adjacent pulses in the order of one microsecond while providing a large number of channels of classification. In its broad aspect the described pulse amplitude analyzer utilizes a storage cathode ray tube und control circuitry whereby the amplitude of the analyzed pulses controls both the intensity and vertical defiection of the beam to charge particular spots in horizontal sectors of the tube face as the beam is moved horizontally across the tube face. As soon as the beam has swept the length of the tube the information stored therein is read out by scanning individually each horizontal sector corresponding to a certain range of pulse amplitudes and applying the output signal from each scan to separate indicating means.

  8. Vector plane wave spectrum of an arbitrary polarized electromagnetic wave.

    PubMed

    Guo, Hanming; Chen, Jiabi; Zhuang, Songlin

    2006-03-20

    By using the method of modal expansions of the independent transverse fields, a formula of vector plane wave spectrum (VPWS) of an arbitrary polarized electromagnetic wave in a homogenous medium is derived. In this formula VPWS is composed of TM- and TE-mode plane wave spectrum, where the amplitude and unit polarized direction of every plane wave are separable, which has more obviously physical meaning and is more convenient to apply in some cases compared to previous formula of VPWS. As an example, the formula of VPWS is applied to the well-known radially and azimuthally polarized beam. In addition, vector Fourier-Bessel transform pairs of an arbitrary polarized electromagnetic wave with circular symmetry are also derived.

  9. Vector plane wave spectrum of an arbitrary polarized electromagnetic wave

    NASA Astrophysics Data System (ADS)

    Guo, Hanming; Chen, Jiabi; Zhuang, Songlin

    2006-03-01

    By using the method of modal expansions of the independent transverse fields, a formula of vector plane wave spectrum (VPWS) of an arbitrary polarized electromagnetic wave in a homogenous medium is derived. In this formula VPWS is composed of TM- and TE-mode plane wave spectrum, where the amplitude and unit polarized direction of every plane wave are separable, which has more obviously physical meaning and is more convenient to apply in some cases compared to previous formula of VPWS. As an example, the formula of VPWS is applied to the well-known radially and azimuthally polarized beam. In addition, vector Fourier-Bessel transform pairs of an arbitrary polarized electromagnetic wave with circular symmetry are also derived.

  10. Effective generation of unidirectional SPP beam with arbitrary profile

    NASA Astrophysics Data System (ADS)

    You, Oubo; Bai, Benfeng; Wu, Xiaoyu; Zhu, Zhendong; Wang, Qixia

    2016-04-01

    The beam formation of SPPs is very important in plasmonics. Different SPP beams could be used for different purposes, such as SPP focusing, non-diffractive SPP wave propagation, efficient SPP coupling, and manipulating particles. Here, we present a straightforward and effective method for generating unidirectionally propagating SPP beams with arbitrary profile in both amplitude and phase by locating the Δ-shaped nanoantennas. The Δ-shape of the nanoantennas is used to achieve unidirectionality of SPPs and the locations of the nanoantennas are controlled to realize arbitrary profile of the excited SPP wave. As examples, several SPP launchers generating different SPP beams are designed with this method. The near-field distribution of the generated SPP beams are also experimentally characterized to validate the effectiveness of this method.

  11. Multichannel 02 and 12 transition amplitudes for arbitrary spin particles in a finite volume

    SciTech Connect

    Hansen, Maxwell; Briceno, Raul

    2015-10-01

    We present a model-independent, non-perturbative relation between finite-volume matrix elements and infinite-volume $\\textbf{0}\\rightarrow\\textbf{2}$ and $\\textbf{1}\\rightarrow\\textbf{2}$ transition amplitudes. Our result accommodates theories in which the final two-particle state is coupled to any number of other two-body channels, with all angular momentum states included. The derivation uses generic, fully relativistic field theory, and is exact up to exponentially suppressed corrections in the lightest particle mass times the box size. This work distinguishes itself from previous studies by accommodating particles with any intrinsic spin. To illustrate the utility of our general result, we discuss how it can be implemented for studies of $N+\\mathcal{J}~\\rightarrow~(N\\pi,N\\eta,N\\eta',\\Sigma K,\\Lambda K)$ transitions, where $\\mathcal{J}$ is a generic external current. The reduction of rotational symmetry, due to the cubic finite volume, manifests in this example through the mixing of S- and P-waves when the system has nonzero total momentum.

  12. The collision effect between dust grains and ions to the dust ion acoustic waves in a dusty plasma

    SciTech Connect

    Yang Xue; Wang Canglong; Liu Congbo; Zhang Jianrong; Shi Yuren; Duan Wenshan; Yang Lei

    2012-10-15

    Damping solitary wave in dusty plasma is studied by considering the collision effect between dust grains and ions. It can be described by a KdV type equation in which a damping term of {phi}{sup 2} exist. It is found that both the amplitude and propagation velocity of the solitary wave decrease with time exponentially. Our results are compared with another KdV type equation with the damping term of {phi}. It is noted that the damping rate of the KdV type equation with the damping term of {phi}{sup 2} is larger than that with the term of {phi}. It is found that the damping rate is proportional to the collision frequency between dust grains and ions.

  13. All one-loop NMHV gluon amplitudes in = 1 SYM

    NASA Astrophysics Data System (ADS)

    Ochirov, Alexander

    2013-12-01

    We compute the next-to-maximally-helicity-violating one-loop n-gluon amplitudes in = 1 super-Yang-Mills theory. These amplitudes contain three negative-helicity gluons and an arbitrary number of positive-helicity gluons, and constitute the first infinite series of amplitudes beyond the simplest, MHV, amplitudes. We assemble ingredients from the = 4 NMHV tree super-amplitude into previously unwritten double cuts and use the spinor integration technique to calculate all bubble coefficients. We also derive the missing box coefficients from quadruple cuts. Together with the known formula for three-mass triangles, this completes the set of NMHV one-loop master integral coefficients in = 1 SYM. To facilitate further use of our results, we provide their Mathematica implementation.

  14. Renormalization of massless Feynman amplitudes in configuration space

    NASA Astrophysics Data System (ADS)

    Nikolov, Nikolay M.; Stora, Raymond; Todorov, Ivan

    2014-05-01

    A systematic study of recursive renormalization of Feynman amplitudes is carried out both in Euclidean and in Minkowski configuration spaces. For a massless quantum field theory (QFT), we use the technique of extending associate homogeneous distributions to complete the renormalization recursion. A homogeneous (Poincaré covariant) amplitude is said to be convergent if it admits a (unique covariant) extension as a homogeneous distribution. For any amplitude without subdivergences — i.e. for a Feynman distribution that is homogeneous off the full (small) diagonal — we define a renormalization invariant residue. Its vanishing is a necessary and sufficient condition for the convergence of such an amplitude. It extends to arbitrary — not necessarily primitively divergent — Feynman amplitudes. This notion of convergence is finer than the usual power counting criterion and includes cancellation of divergences.

  15. Equientangled bases in arbitrary dimensions

    SciTech Connect

    Karimipour, V.; Memarzadeh, L.

    2006-01-15

    For the space of two identical systems of arbitrary dimensions, we introduce a continuous family of bases with the following properties: (i) the bases are orthonormal (ii) in each basis, all the states have the same values of entanglement, and (iii) they continuously interpolate between the product basis and the maximally entangled basis. The states thus constructed may find applications in many areas related to the quantum information science including quantum cryptography, optimal Bell tests, and the investigation of the enhancement of channel capacity due to entanglement.

  16. Full-Polarization 3D Metasurface Cloak with Preserved Amplitude and Phase.

    PubMed

    Yang, Yihao; Jing, Liqiao; Zheng, Bin; Hao, Ran; Yin, Wenyan; Li, Erping; Soukoulis, Costas M; Chen, Hongsheng

    2016-08-01

    A full-polarization arbitrary-shaped 3D metasurface cloak with preserved amplitude and phase in microwave frequencies is experimentally demonstrated. By taking the unique feature of metasurfaces, it is shown that the cloak can completely restore the polarization, amplitude, and phase of light for full polarization as if light was incident on a flat mirror. PMID:27218885

  17. Quantitative phase retrieval with arbitrary pupil and illumination

    DOE PAGES

    Claus, Rene A.; Naulleau, Patrick P.; Neureuther, Andrew R.; Waller, Laura

    2015-10-02

    We present a general algorithm for combining measurements taken under various illumination and imaging conditions to quantitatively extract the amplitude and phase of an object wave. The algorithm uses the weak object transfer function, which incorporates arbitrary pupil functions and partially coherent illumination. The approach is extended beyond the weak object regime using an iterative algorithm. Finally, we demonstrate the method on measurements of Extreme Ultraviolet Lithography (EUV) multilayer mask defects taken in an EUV zone plate microscope with both a standard zone plate lens and a zone plate implementing Zernike phase contrast.

  18. Quantitative phase retrieval with arbitrary pupil and illumination.

    PubMed

    Claus, Rene A; Naulleau, Patrick P; Neureuther, Andrew R; Waller, Laura

    2015-10-01

    We present a general algorithm for combining measurements taken under various illumination and imaging conditions to quantitatively extract the amplitude and phase of an object wave. The algorithm uses the weak object transfer function, which incorporates arbitrary pupil functions and partially coherent illumination. The approach is extended beyond the weak object regime using an iterative algorithm. We demonstrate the method on measurements of Extreme Ultraviolet Lithography (EUV) multilayer mask defects taken in an EUV zone plate microscope with both a standard zone plate lens and a zone plate implementing Zernike phase contrast. PMID:26480180

  19. Three-dimensional dust-ion-acoustic rogue waves in a magnetized dusty pair-ion plasma with nonthermal nonextensive electrons and opposite polarity dust grains

    SciTech Connect

    Guo, Shimin Mei, Liquan

    2014-08-15

    Dust-ion-acoustic (DIA) rogue waves are investigated in a three-dimensional magnetized plasma containing nonthermal electrons featuring Tsallis distribution, both positive and negative ions, and immobile dust grains having both positive and negative charges. Via the reductive perturbation method, a (3 + 1)-dimensional nonlinear Schrödinger (NLS) equation is derived to govern the dynamics of the DIA wave packets. The modulation instability of DIA waves described by the (3 + 1)-dimensional NLS equation is investigated. By means of the similarity transformation and symbolic computation, both the first- and second-order rogue wave solutions of the (3 + 1)-dimensional NLS equation are constructed in terms of rational functions. Moreover, the dynamics properties and the effects of plasma parameters on the nonlinear structures of rogue waves are discussed in detail. The results could be useful for understanding the physical mechanism of rogue waves in laboratory experiments where pair-ion plasmas with electrons and dust grains can be found.

  20. Electrostatic ion (hydrogen) cyclotron and ion acoustic wave instabilities in regions of upward field-aligned current and upward ion beams

    NASA Astrophysics Data System (ADS)

    Bergmann, R.

    1984-02-01

    An investigation is made into the stability of electrostatic hydrogen ion cyclotron and ion acoustic waves in a model plasma where an ion beam, population 2, and oppositely directed drifting electrons pass through a stationary ion background, population 1. The excited wave properties are then compared with the characteristics of the unstable modes observed on the S3-3 satellite. Three temperature regimes are studied: (1) Te greater than Ti2 much greater than Ti1, (2) Ti2 greater than Te not less than Ti1, and (3) Te approximately equal to Ti1 greater than Ti2. It is found that the ion beam acts as a free energy source only in regime 1. This regime is also highly unstable to the electrons as a free energy source. Unstable modes in regimes 2 and 3 seem to best satisfy the electrostatic hydrogen cyclotron wave (EHC) properties at 1 earth radius. For these cases the electrons are the free energy source, the beam supplies damping.

  1. Electrostatic ion (hydrogen) cyclotron and ion acoustic wave instabilities in regions of upward field-aligned current and upward ion beams

    NASA Technical Reports Server (NTRS)

    Bergmann, R.

    1984-01-01

    An investigation is made into the stability of electrostatic hydrogen ion cyclotron and ion acoustic waves in a model plasma where an ion beam, population 2, and oppositely directed drifting electrons pass through a stationary ion background, population 1. The excited wave properties are then compared with the characteristics of the unstable modes observed on the S3-3 satellite. Three temperature regimes are studied: (1) Te greater than Ti2 much greater than Ti1, (2) Ti2 greater than Te not less than Ti1, and (3) Te approximately equal to Ti1 greater than Ti2. It is found that the ion beam acts as a free energy source only in regime 1. This regime is also highly unstable to the electrons as a free energy source. Unstable modes in regimes 2 and 3 seem to best satisfy the electrostatic hydrogen cyclotron wave (EHC) properties at 1 earth radius. For these cases the electrons are the free energy source, the beam supplies damping.

  2. The linear and non-linear characterization of dust ion acoustic mode in complex plasma in presence of dynamical charging of dust

    SciTech Connect

    Bhattacharjee, Saurav Das, Nilakshi

    2015-10-15

    A systematic theoretical investigation has been carried out on the role of dust charging dynamics on the nature and stability of DIA (Dust Ion Acoustic) mode in complex plasma. The study has been made for both linear and non-linear scale regime of DIA mode. The observed results have been characterized in terms of background plasma responses towards dust surface responsible for dust charge fluctuation, invoking important dusty plasma parameters, especially the ion flow speed and dust size. The linear analyses confirm the nature of instability in DIA mode in presence of dust charge fluctuation. The instability shows a damping of DIA mode in subsonic flow regime followed by a gradual growth in instability in supersonic limit of ion flow. The strength of non-linearity and their existence domain is found to be driven by different dusty plasma parameters. As dust is ubiquitous in interstellar medium with plasma background, the study also addresses the possible effect of dust charging dynamics in gravito-electrostatic characterization and the stability of dust molecular clouds especially in proto-planetary disc. The observations are influential and interesting towards the understanding of dust settling mechanism and formation of dust environments in different regions in space.

  3. Mitigation of two-plasmon decay in direct-drive inertial confinement fusion through the manipulation of ion-acoustic and Langmuir wave damping

    SciTech Connect

    Myatt, J. F.; Short, R. W.; Maximov, A. V.; Vu, H. X.; DuBois, D. F.; Russell, D. A.; Zhang, J.

    2013-05-15

    The extended Zakharov model of the two-plasmon decay instability in an inhomogeneous plasma [D. F. DuBois et al., Phys. Rev. Lett. 74, 3983 (1995); D. A. Russell and D. F. DuBois, Phys. Rev. Lett. 86, 428 (2001)] is further generalized to include the evolution of the electron distribution function in the quasi-linear approximation [cf., e.g., K. Y. Sanbonmatsu et al. Phys. Plasmas 7, 2824 (2000); D. A. Russell et al., paper presented at the Workshop on SRS/SBS Saturation, Wente Vineyards, Livermore, CA, 2–5 April 2002]. This makes it possible to investigate anomalous absorption of laser light and hot electron production due to the two-plasmon decay instability of multiple overlapping electromagnetic waves. Scalings of hot-electron production in the (stationary) nonlinearly saturated regime relevant to recent experiments [B. Yaakobi et al., Phys. Plasmas 19, 012704 (2012); D. H. Froula et al., Phys. Rev. Lett. 108, 165003 (2012)] have been obtained. They indicate a sensitivity to ion-acoustic wave (IAW) damping and to the collisional absorption of Langmuir waves. Such a sensitivity might be exploited in inertial confinement fusion target design by the use of mid-Z ablators.

  4. Propagation of ion-acoustic solitons in an electron beam-superthermal plasma system with finite ion-temperature: Linear and fully nonlinear investigation

    SciTech Connect

    Saberian, E.; Esfandyari-Kalejahi, A.; Rastkar-Ebrahimzadeh, A.; Afsari-Ghazi, M.

    2013-03-15

    The propagation of ion-acoustic (IA) solitons is studied in a plasma system, comprised of warm ions and superthermal (Kappa distributed) electrons in the presence of an electron-beam by using a hydrodynamic model. In the linear analysis, it is seen that increasing the superthermality lowers the phase speed of the IA waves. On the other hand, in a fully nonlinear investigation, the Mach number range and characteristics of IA solitons are analyzed, parametrically and numerically. It is found that the accessible region for the existence of IA solitons reduces with increasing the superthermality. However, IA solitons with both negative and positive polarities can coexist in the system. Additionally, solitary waves with both subsonic and supersonic speeds are predicted in the plasma, depending on the value of ion-temperature and the superthermality of electrons in the system. It is examined that there are upper critical values for beam parameters (i.e., density and velocity) after which, IA solitary waves could not propagate in the plasma. Furthermore, a typical interaction between IA waves and the electron-beam in the plasma is confirmed.

  5. Compound words prompt arbitrary semantic associations in conceptual memory

    PubMed Central

    Boutonnet, Bastien; McClain, Rhonda; Thierry, Guillaume

    2014-01-01

    Linguistic relativity theory has received empirical support in domains such as color perception and object categorization. It is unknown, however, whether relations between words idiosyncratic to language impact non-verbal representations and conceptualizations. For instance, would one consider the concepts of horse and sea as related were it not for the existence of the compound seahorse? Here, we investigated such arbitrary conceptual relationships using a non-linguistic picture relatedness task in participants undergoing event-related brain potential recordings. Picture pairs arbitrarily related because of a compound and presented in the compound order elicited N400 amplitudes similar to unrelated pairs. Surprisingly, however, pictures presented in the reverse order (as in the sequence horse–sea) reduced N400 amplitudes significantly, demonstrating the existence of a link in memory between these two concepts otherwise unrelated. These results break new ground in the domain of linguistic relativity by revealing predicted semantic associations driven by lexical relations intrinsic to language. PMID:24672505

  6. Compound words prompt arbitrary semantic associations in conceptual memory.

    PubMed

    Boutonnet, Bastien; McClain, Rhonda; Thierry, Guillaume

    2014-01-01

    Linguistic relativity theory has received empirical support in domains such as color perception and object categorization. It is unknown, however, whether relations between words idiosyncratic to language impact non-verbal representations and conceptualizations. For instance, would one consider the concepts of horse and sea as related were it not for the existence of the compound seahorse? Here, we investigated such arbitrary conceptual relationships using a non-linguistic picture relatedness task in participants undergoing event-related brain potential recordings. Picture pairs arbitrarily related because of a compound and presented in the compound order elicited N400 amplitudes similar to unrelated pairs. Surprisingly, however, pictures presented in the reverse order (as in the sequence horse-sea) reduced N400 amplitudes significantly, demonstrating the existence of a link in memory between these two concepts otherwise unrelated. These results break new ground in the domain of linguistic relativity by revealing predicted semantic associations driven by lexical relations intrinsic to language. PMID:24672505

  7. Reinforcing Saccadic Amplitude Variability

    ERIC Educational Resources Information Center

    Paeye, Celine; Madelain, Laurent

    2011-01-01

    Saccadic endpoint variability is often viewed as the outcome of neural noise occurring during sensorimotor processing. However, part of this variability might result from operant learning. We tested this hypothesis by reinforcing dispersions of saccadic amplitude distributions, while maintaining constant their medians. In a first experiment we…

  8. Arbitrary p-form Galileons

    SciTech Connect

    Deffayet, C.; Deser, S.; Esposito-Farese, G.

    2010-09-15

    We show that scalar, 0-form, Galileon actions--models whose field equations contain only second derivatives--can be generalized to arbitrary even p-forms. More generally, they need not even depend on a single form, but may involve mixed p combinations, including equal p multiplets, where odd p fields are also permitted: We construct, for given dimension D, general actions depending on scalars, vectors, and higher p-form field strengths, whose field equations are of exactly second derivative order. We also discuss and illustrate their curved-space generalizations, especially the delicate nonminimal couplings required to maintain this order. Concrete examples of pure and mixed actions, field equations, and their curved-space extensions are presented.

  9. Hyperspherical harmonics with arbitrary arguments

    SciTech Connect

    Meremianin, A. V.

    2009-01-15

    The derivation scheme for hyperspherical harmonics (HSH) with arbitrary arguments is proposed. It is demonstrated that HSH can be presented as the product of HSH corresponding to spaces with lower dimensionality multiplied by the orthogonal (Jacobi or Gegenbauer) polynomial. The relation of HSH to quantum few-body problems is discussed. The explicit expressions for orthonormal HSH in spaces with dimensions from two to six are given. The important particular cases of four- and six-dimensional spaces are analyzed in detail and explicit expressions for HSH are given for several choices of hyperangles. In the six-dimensional space, HSH representing the kinetic-energy operator corresponding to (i) the three-body problem in physical space and (ii) four-body planar problem are derived.

  10. Hyperspherical harmonics with arbitrary arguments

    NASA Astrophysics Data System (ADS)

    Meremianin, A. V.

    2009-01-01

    The derivation scheme for hyperspherical harmonics (HSH) with arbitrary arguments is proposed. It is demonstrated that HSH can be presented as the product of HSH corresponding to spaces with lower dimensionality multiplied by the orthogonal (Jacobi or Gegenbauer) polynomial. The relation of HSH to quantum few-body problems is discussed. The explicit expressions for orthonormal HSH in spaces with dimensions from two to six are given. The important particular cases of four- and six-dimensional spaces are analyzed in detail and explicit expressions for HSH are given for several choices of hyperangles. In the six-dimensional space, HSH representing the kinetic-energy operator corresponding to (i) the three-body problem in physical space and (ii) four-body planar problem are derived.

  11. Resonance capture at arbitrary inclination

    NASA Astrophysics Data System (ADS)

    Namouni, F.; Morais, M. H. M.

    2015-01-01

    Resonance capture is studied numerically in the three-body problem for arbitrary inclinations. Massless particles are set to drift from outside the 1:5 resonance with a Jupiter-mass planet thereby encountering the web of the planet's diverse mean motion resonances. Randomly constructed samples explore parameter space for inclinations from 0 to 180° with 5° increments totalling nearly 6 × 105 numerical simulations. 30 resonances internal and external to the planet's location are monitored. We find that retrograde resonances are unexpectedly more efficient at capture than prograde resonances and that resonance order is not necessarily a good indicator of capture efficiency at arbitrary inclination. Capture probability drops significantly at moderate sample eccentricity for initial inclinations in the range [10°,110°]. Orbit inversion is possible for initially circular orbits with inclinations in the range [60°,130°]. Capture in the 1:1 co-orbital resonance occurs with great likelihood at large retrograde inclinations. The planet's orbital eccentricity, if larger than 0.1, reduces the capture probabilities through the action of the eccentric Kozai-Lidov mechanism. A capture asymmetry appears between inner and outer resonances as prograde orbits are preferentially trapped in inner resonances. The relative capture efficiency of retrograde resonance suggests that the dynamical lifetimes of Damocloids and Centaurs on retrograde orbits must be significantly larger than those on prograde orbits implying that the recently identified asteroids in retrograde resonance, 2006 BZ8, 2008 SO218, 2009 QY6 and 1999 LE31 may be among the oldest small bodies that wander between the outer giant planets.

  12. A compact, multichannel, and low noise arbitrary waveform generator.

    PubMed

    Govorkov, S; Ivanov, B I; Il'ichev, E; Meyer, H-G

    2014-05-01

    A new type of high functionality, fast, compact, and easy programmable arbitrary waveform generator for low noise physical measurements is presented. The generator provides 7 fast differential waveform channels with a maximum bandwidth up to 200 MHz frequency. There are 6 fast pulse generators on the generator board with 78 ps time resolution in both duration and delay, 3 of them with amplitude control. The arbitrary waveform generator is additionally equipped with two auxiliary slow 16 bit analog-to-digital converters and four 16 bit digital-to-analog converters for low frequency applications. Electromagnetic shields are introduced to the power supply, digital, and analog compartments and with a proper filter design perform more than 110 dB digital noise isolation to the output signals. All the output channels of the board have 50 Ω SubMiniature version A termination. The generator board is suitable for use as a part of a high sensitive physical equipment, e.g., fast read out and manipulation of nuclear magnetic resonance or superconducting quantum systems and any other application, which requires electromagnetic interference free fast pulse and arbitrary waveform generation.

  13. A compact, multichannel, and low noise arbitrary waveform generator

    SciTech Connect

    Govorkov, S.; Ivanov, B. I.; Il'ichev, E.; Meyer, H.-G.

    2014-05-15

    A new type of high functionality, fast, compact, and easy programmable arbitrary waveform generator for low noise physical measurements is presented. The generator provides 7 fast differential waveform channels with a maximum bandwidth up to 200 MHz frequency. There are 6 fast pulse generators on the generator board with 78 ps time resolution in both duration and delay, 3 of them with amplitude control. The arbitrary waveform generator is additionally equipped with two auxiliary slow 16 bit analog-to-digital converters and four 16 bit digital-to-analog converters for low frequency applications. Electromagnetic shields are introduced to the power supply, digital, and analog compartments and with a proper filter design perform more than 110 dB digital noise isolation to the output signals. All the output channels of the board have 50 Ω SubMiniature version A termination. The generator board is suitable for use as a part of a high sensitive physical equipment, e.g., fast read out and manipulation of nuclear magnetic resonance or superconducting quantum systems and any other application, which requires electromagnetic interference free fast pulse and arbitrary waveform generation.

  14. Syzygies probing scattering amplitudes

    NASA Astrophysics Data System (ADS)

    Chen, Gang; Liu, Junyu; Xie, Ruofei; Zhang, Hao; Zhou, Yehao

    2016-09-01

    We propose a new efficient algorithm to obtain the locally minimal generating set of the syzygies for an ideal, i.e. a generating set whose proper subsets cannot be generating sets. Syzygy is a concept widely used in the current study of scattering amplitudes. This new algorithm can deal with more syzygies effectively because a new generation of syzygies is obtained in each step and the irreducibility of this generation is also verified in the process. This efficient algorithm can also be applied in getting the syzygies for the modules. We also show a typical example to illustrate the potential application of this method in scattering amplitudes, especially the Integral-By-Part(IBP) relations of the characteristic two-loop diagrams in the Yang-Mills theory.

  15. Double layers and double wells in arbitrary degenerate plasmas

    NASA Astrophysics Data System (ADS)

    Akbari-Moghanjoughi, M.

    2016-06-01

    Using the generalized hydrodynamic model, the possibility of variety of large amplitude nonlinear excitations is examined in electron-ion plasma with arbitrary electron degeneracy considering also the ion temperature effect. A new energy-density relation is proposed for plasmas with arbitrary electron degeneracy which reduces to the classical Boltzmann and quantum Thomas-Fermi counterparts in the extreme limits. The pseudopotential method is employed to find the criteria for existence of nonlinear structures such as solitons, periodic nonlinear structures, and double-layers for different cases of adiabatic and isothermal ion fluids for a whole range of normalized electron chemical potential, η0, ranging from dilute classical to completely degenerate electron fluids. It is observed that there is a Mach-speed gap in which no large amplitude localized or periodic nonlinear excitations can propagate in the plasma under consideration. It is further revealed that the plasma under investigation supports propagation of double-wells and double-layers the chemical potential and Mach number ranges of which are studied in terms of other plasma parameters. The Mach number criteria for nonlinear waves are shown to significantly differ for cases of classical with η0 < 0 and quantum with η0 > 0 regimes. It is also shown that the localized structure propagation criteria possess significant dissimilarities for plasmas with adiabatic and isothermal ions. Current research may be generalized to study the nonlinear structures in plasma containing positrons, multiple ions with different charge states, and charged dust grains.

  16. Infrared singularities of scattering amplitudes in perturbative QCD

    SciTech Connect

    Becher, Thomas; Neubert, Matthias

    2013-11-01

    An exact formula is derived for the infrared singularities of dimensionally regularized scattering amplitudes in massless QCD with an arbitrary number of legs, valid at any number of loops. It is based on the conjecture that the anomalous-dimension matrix of n-jet operators in soft-collinear effective theory contains only a single non-trivial color structure, whose coefficient is the cusp anomalous dimension of Wilson loops with light-like segments. Its color-diagonal part is characterized by two anomalous dimensions, which are extracted to three-loop order from known perturbative results for the quark and gluon form factors. This allows us to predict the three-loop coefficients of all 1/epsilon^k poles for an arbitrary n-parton scattering amplitudes, generalizing existing two-loop results.

  17. Stability of ion acoustic solitary waves in a magnetized plasma consisting of warm adiabatic ions and non-thermal electrons having vortex-like velocity distribution

    NASA Astrophysics Data System (ADS)

    Das, Jayasree; Bandyopadhyay, Anup; Das, K. P.; Das

    2014-02-01

    Schamel's modified Korteweg-de Vries-Zakharov-Kuznetsov (S-ZK) equation, governing the behavior of long wavelength, weak nonlinear ion acoustic waves propagating obliquely to an external uniform static magnetic field in a plasma consisting of warm adiabatic ions and non-thermal electrons (due to the presence of fast energetic electrons) having vortex-like velocity distribution function (due to the presence of trapped electrons), immersed in a uniform (space-independent) and static (time-independent) magnetic field, admits solitary wave solutions having a sech 4 profile. The higher order stability of this solitary wave solution of the S-ZK equation has been analyzed with the help of multiple-scale perturbation expansion method of Allen and Rowlands (Allen, M. A. and Rowlands, G. 1993 J. Plasma Phys. 50, 413; 1995 J. Plasma Phys. 53, 63). The growth rate of instability is obtained correct to the order k 2, where k is the wave number of a long wavelength plane wave perturbation. It is found that the lowest order (at the order k) instability condition is strongly sensitive to the angle of propagation (δ) of the solitary wave with the external uniform static magnetic field, whereas at the next order (at the order k 2) the solitary wave solutions of the S-ZK equation are unstable irrespective of δ. It is also found that the growth rate of instability up to the order k 2 for the electrons having Boltzmann distribution is higher than that of the non-thermal electrons having vortex-like distribution for any fixed δ.

  18. Controlling arbitrary humidity without convection.

    PubMed

    Wasnik, Priyanka S; N'guessan, Hartmann E; Tadmor, Rafael

    2015-10-01

    In this paper we show a way that allows for the first time to induce arbitrary humidity of desired value for systems without convective flow. To enable this novelty we utilize a semi-closed environment in which evaporation is not completely suppressed. In this case, the evaporation rate is determined both by the outer (open) humidity and by the inner (semi-closed) geometry including the size/shape of the evaporating medium and the size/shape of the semi-closure. We show how such systems can be used to induce desired humidity conditions. We consider water droplet placed on a solid surface and study its evaporation when it is surrounded by other drops, hereon "satellite" drops and covered by a semi-closed hemisphere. The main drop's evaporation rate is proportional to its height, in agreement with theory. Surprisingly, however, the influence of the satellite drops on the main drop's evaporation suppression is not proportional to the sum of heights of the satellite drops. Instead, it shows proportionality close to the satellite drops' total surface area. The resultant humidity conditions in the semi-closed system can be effectively and accurately induced using different satellite drops combinations. PMID:26072445

  19. Controlling arbitrary humidity without convection.

    PubMed

    Wasnik, Priyanka S; N'guessan, Hartmann E; Tadmor, Rafael

    2015-10-01

    In this paper we show a way that allows for the first time to induce arbitrary humidity of desired value for systems without convective flow. To enable this novelty we utilize a semi-closed environment in which evaporation is not completely suppressed. In this case, the evaporation rate is determined both by the outer (open) humidity and by the inner (semi-closed) geometry including the size/shape of the evaporating medium and the size/shape of the semi-closure. We show how such systems can be used to induce desired humidity conditions. We consider water droplet placed on a solid surface and study its evaporation when it is surrounded by other drops, hereon "satellite" drops and covered by a semi-closed hemisphere. The main drop's evaporation rate is proportional to its height, in agreement with theory. Surprisingly, however, the influence of the satellite drops on the main drop's evaporation suppression is not proportional to the sum of heights of the satellite drops. Instead, it shows proportionality close to the satellite drops' total surface area. The resultant humidity conditions in the semi-closed system can be effectively and accurately induced using different satellite drops combinations.

  20. Optical arbitrary waveform characterization using linear spectrograms.

    PubMed

    Jiang, Zhi; Leaird, Daniel E; Long, Christopher M; Boppart, Stephen A; Weiner, Andrew M

    2010-08-01

    We demonstrate the first application of linear spectrogram methods based on electro-optic phase modulation to characterize optical arbitrary waveforms generated under spectral line-by-line control. This approach offers both superior sensitivity and self-referencing capability for retrieval of periodic high repetition rate optical arbitrary waveforms.

  1. Optical arbitrary waveform characterization using linear spectrograms

    PubMed Central

    Jiang, Zhi; Leaird, Daniel E.; Long, Christopher M.; Boppart, Stephen A.; Weiner, Andrew M.

    2010-01-01

    We demonstrate the first application of linear spectrogram methods based on electro-optic phase modulation to characterize optical arbitrary waveforms generated under spectral line-by-line control. This approach offers both superior sensitivity and self-referencing capability for retrieval of periodic high repetition rate optical arbitrary waveforms. PMID:21359161

  2. Observations of large-amplitude, parallel, electrostatic waves associated with the Kelvin-Helmholtz instability by the magnetospheric multiscale mission

    NASA Astrophysics Data System (ADS)

    Wilder, F. D.; Ergun, R. E.; Schwartz, S. J.; Newman, D. L.; Eriksson, S.; Stawarz, J. E.; Goldman, M. V.; Goodrich, K. A.; Gershman, D. J.; Malaspina, D. M.; Holmes, J. C.; Sturner, A. P.; Burch, J. L.; Torbert, R. B.; Lindqvist, P.-A.; Marklund, G. T.; Khotyaintsev, Y.; Strangeway, R. J.; Russell, C. T.; Pollock, C. J.; Giles, B. L.; Dorrelli, J. C.; Avanov, L. A.; Patterson, W. R.; Plaschke, F.; Magnes, W.

    2016-09-01

    On 8 September 2015, the four Magnetospheric Multiscale spacecraft encountered a Kelvin-Helmholtz unstable magnetopause near the dusk flank. The spacecraft observed periodic compressed current sheets, between which the plasma was turbulent. We present observations of large-amplitude (up to 100 mV/m) oscillations in the electric field. Because these oscillations are purely parallel to the background magnetic field, electrostatic, and below the ion plasma frequency, they are likely to be ion acoustic-like waves. These waves are observed in a turbulent plasma where multiple particle populations are intermittently mixed, including cold electrons with energies less than 10 eV. Stability analysis suggests a cold electron component is necessary for wave growth.

  3. Experimental generation of amplitude squeezed vector beams.

    PubMed

    Chille, Vanessa; Berg-Johansen, Stefan; Semmler, Marion; Banzer, Peter; Aiello, Andrea; Leuchs, Gerd; Marquardt, Christoph

    2016-05-30

    We present an experimental method for the generation of amplitude squeezed high-order vector beams. The light is modified twice by a spatial light modulator such that the vector beam is created by means of a collinear interferometric technique. A major advantage of this approach is that it avoids systematic losses, which are detrimental as they cause decoherence in continuous-variable quantum systems. The utilisation of a spatial light modulator (SLM) gives the flexibility to switch between arbitrary mode orders. The conversion efficiency with our setup is only limited by the efficiency of the SLM. We show the experimental generation of Laguerre-Gauss (LG) modes with radial indices 0 or 1 and azimuthal indices up to 3 with complex polarization structures and a quantum noise reduction up to -0.9dB±0.1dB. The corresponding polarization structures are studied in detail by measuring the spatial distribution of the Stokes parameters. PMID:27410153

  4. Arbitrary amplitude fast electron-acoustic solitons in three-electron component space plasmas

    NASA Astrophysics Data System (ADS)

    Mbuli, L. N.; Maharaj, S. K.; Bharuthram, R.; Singh, S. V.; Lakhina, G. S.

    2016-06-01

    We examine the characteristics of fast electron-acoustic solitons in a four-component unmagnetised plasma model consisting of cool, warm, and hot electrons, and cool ions. We retain the inertia and pressure for all the plasma species by assuming adiabatic fluid behaviour for all the species. By using the Sagdeev pseudo-potential technique, the allowable Mach number ranges for fast electron-acoustic solitary waves are explored and discussed. It is found that the cool and warm electron number densities determine the polarity switch of the fast electron-acoustic solitons which are limited by either the occurrence of fast electron-acoustic double layers or warm and hot electron number density becoming unreal. For the first time in the study of solitons, we report on the coexistence of fast electron-acoustic solitons, in addition to the regular fast electron-acoustic solitons and double layers in our multi-species plasma model. Our results are applied to the generation of broadband electrostatic noise in the dayside auroral region.

  5. Closed string amplitudes as single-valued open string amplitudes

    NASA Astrophysics Data System (ADS)

    Stieberger, Stephan; Taylor, Tomasz R.

    2014-04-01

    We show that the single trace heterotic N-point tree-level gauge amplitude ANHET can be obtained from the corresponding type I amplitude ANI by the single-valued (sv) projection: ANHET=sv(ANI). This projection maps multiple zeta values to single-valued multiple zeta values. The latter represent a subclass of multiple zeta values originating from single-valued multiple polylogarithms at unity. Similar relations between open and closed string amplitudes or amplitudes of different string vacua can be established. As a consequence the α‧-expansion of a closed string amplitude is dictated by that of the corresponding open string amplitude. The combination of single-valued projections, Kawai-Lewellen-Tye relations and Mellin correspondence reveal a unity of all tree-level open and closed superstring amplitudes together with the maximally supersymmetric Yang-Mills and supergravity theories.

  6. Berends-Giele recursion for double-color-ordered amplitudes

    NASA Astrophysics Data System (ADS)

    Mafra, Carlos R.

    2016-07-01

    Tree-level double-color-ordered amplitudes are computed using Berends-Giele recursion relations applied to the bi-adjoint cubic scalar theory. The standard notion of Berends-Giele currents is generalized to double-currents and their recursions are derived from a perturbiner expansion of linearized fields that solve the non-linear field equations. Two applications are given. Firstly, we prove that the entries of the inverse KLT matrix are equal to Berends-Giele double-currents (and are therefore easy to compute). And secondly, a simple formula to generate tree-level BCJ-satisfying numerators for arbitrary multiplicity is proposed by evaluating the field-theory limit of tree-level string amplitudes for various color orderings using double-color-ordered amplitudes.

  7. Loop Integrands for Scattering Amplitudes from the Riemann Sphere

    NASA Astrophysics Data System (ADS)

    Geyer, Yvonne; Mason, Lionel; Monteiro, Ricardo; Tourkine, Piotr

    2015-09-01

    The scattering equations on the Riemann sphere give rise to remarkable formulas for tree-level gauge theory and gravity amplitudes. Adamo, Casali, and Skinner conjectured a one-loop formula for supergravity amplitudes based on scattering equations on a torus. We use a residue theorem to transform this into a formula on the Riemann sphere. What emerges is a framework for loop integrands on the Riemann sphere that promises to have a wide application, based on off-shell scattering equations that depend on the loop momentum. We present new formulas, checked explicitly at low points, for supergravity and super-Yang-Mills amplitudes and for n -gon integrands at one loop. Finally, we show that the off-shell scattering equations naturally extend to arbitrary loop order, and we give a proposal for the all-loop integrands for supergravity and planar super-Yang-Mills theory.

  8. Determining pseudoscalar meson photoproduction amplitudes from complete experiments

    SciTech Connect

    A. M. Sandorfi, S. Hoblit, H. Kamano, T.-S. H. Lee

    2011-05-01

    In preparation for a new generation of complete experiments with the goal of performing a high precision extraction of pseudoscalar meson photo-production amplitudes, we present expressions that allow the direct numerical calculation of matrix elements with arbitrary spin projections from Chew-Goldberger-Low-Nambu (CGLN) amplitudes. We use this numerical tool to verify the most general analytic form of the cross section, dependent upon the three polarization vectors of the beam, target and recoil baryon, including all single, double and triple-polarization terms involving 16 spin-dependent observables. Analytic expressions that determine the recoil baryon polarization are presented, together with examples of their potential use with quasi-4? detectors to deduce observables. We assemble the analytic equations relating the 16 experimental observables and the CGLN amplitudes and use our independent method of numerical evaluation to resolve sign differences that exist in the literature.

  9. PULSE AMPLITUDE DISTRIBUTION RECORDER

    DOEpatents

    Cowper, G.

    1958-08-12

    A device is described for automatica1ly recording pulse annplitude distribution received from a counter. The novelty of the device consists of the over-all arrangement of conventional circuit elements to provide an easy to read permanent record of the pulse amplitude distribution during a certain time period. In the device a pulse analyzer separates the pulses according to annplitude into several channels. A scaler in each channel counts the pulses and operates a pen marker positioned over a drivable recorder sheet. Since the scalers in each channel have the sanne capacity, the control circuitry permits counting of the incoming pulses until one scaler reaches capacity, whereupon the input is removed and an internal oscillator supplies the necessary pulses to fill up the other scalers. Movement of the chart sheet is initiated wben the first scaler reaches capacity to thereby give a series of marks at spacings proportional to the time required to fill the remaining scalers, and accessory equipment marks calibration points on the recorder sheet to facilitate direct reading of the number of external pulses supplied to each scaler.

  10. From arbitrariness to anomalies in two-dimensional perturbative calculations

    NASA Astrophysics Data System (ADS)

    Battistel, O. A.

    2004-05-01

    A very general calculational strategy is applied to the evaluation of divergent physical amplitudes which are typical of 2D perturbative calculations. With this approach, in the final results all the arbitrariness intrinsic to the calculations, due to the divergent character, is still present. We show that, concerning the arbitrariness, the regularizations can be classified into two basic classes. The consequences on adopting each such class for the symmetry relations are investigated. It is noted that if very general symmetry requirements, such as Furry's theorem or gauge invariance, are used to select a consistent regularization procedure, the possible sources of ambiguities related to the choices for the internal line momenta of loops are completely eliminated. A very transparent description of the two-dimensional anomalies emerges, allowing a clear understanding of the results obtained within the context of traditional methods. The comparison with 4D triangle anomalies reveals a completely similar situation for both cases. The very interesting phenomenon of mass generation for the gauge boson in the massless fermion theory is also obtained in agreement with the expected results.

  11. Full one-loop amplitudes from tree amplitudes

    SciTech Connect

    Giele, Walter T.; Kunszt, Zoltan; Melnikov, Kirill; /Hawaii U.

    2008-01-01

    We establish an efficient polynomial-complexity algorithm for one-loop calculations, based on generalized D-dimensional unitarity. It allows automated computations of both cut-constructible and rational parts of one-loop scattering amplitudes from on-shell tree amplitudes. We illustrate the method by (re)-computing all four-, five- and six-gluon scattering amplitudes in QCD at one-loop.

  12. Feynman amplitudes with confinement included

    NASA Astrophysics Data System (ADS)

    Simonov, Yu. A.

    2009-07-01

    Amplitudes for any multipoint Feynman diagram are written taking into account vacuum background confining field. Higher order gluon exchanges are treated within background perturbation theory. For amplitudes with hadrons in initial or final states vertices are shown to be expressed by the corresponding wave function with the renormalized z factors. Examples of two-point functions, three-point functions (form factors), and decay amplitudes are explicitly considered.

  13. On the Period-Amplitude and Amplitude-Period Relationships

    NASA Technical Reports Server (NTRS)

    Wilson, Robert M.; Hathaway, David H.

    2008-01-01

    Examined are Period-Amplitude and Amplitude-Period relationships based on the cyclic behavior of the 12-month moving averages of monthly mean sunspot numbers for cycles 0.23, both in terms of Fisher's exact tests for 2x2 contingency tables and linear regression analyses. Concerning the Period-Amplitude relationship (same cycle), because cycle 23's maximum amplitude is known to be 120.8, the inferred regressions (90-percent prediction intervals) suggest that its period will be 131 +/- 24 months (using all cycles) or 131 +/- 18 months (ignoring cycles 2 and 4, which have the extremes of period, 108 and 164 months, respectively). Because cycle 23 has already persisted for 142 months (May 1996 through February 2008), based on the latter prediction, it should end before September 2008. Concerning the Amplitude-Period relationship (following cycle maximum amplitude versus preceding cycle period), because cycle 23's period is known to be at least 142 months, the inferred regressions (90-percent prediction intervals) suggest that cycle 24's maximum amplitude will be about less than or equal to 96.1 +/- 55.0 (using all cycle pairs) or less than or equal to 91.0 +/- 36.7 (ignoring statistical outlier cycle pairs). Hence, cycle 24's maximum amplitude is expected to be less than 151, perhaps even less than 128, unless cycle pair 23/24 proves to be a statistical outlier.

  14. Dirichlet series as interfering probability amplitudes for quantum measurements

    NASA Astrophysics Data System (ADS)

    Feiler, C.; Schleich, W. P.

    2015-06-01

    We show that all Dirichlet series, linear combinations of them and their analytical continuations represent probability amplitudes for measurements on time-dependent quantum systems. In particular, we connect an arbitrary Dirichlet series to the time evolution of an appropriately prepared quantum state in a non-linear oscillator with logarithmic energy spectrum. However, the realization of a superposition of two Dirichlet sums and its analytical continuation requires two quantum systems which are entangled, and a joint measurement. We illustrate our approach of implementing arbitrary Dirichlet series in quantum systems using the example of the Riemann zeta function and relate its non-trivial zeros to the interference of two quantum states reminiscent of a Schrödinger cat.

  15. Rolling bearing stiffness in arbitrary direction

    NASA Astrophysics Data System (ADS)

    Luo, Zhusan; Sun, Xinde; Wu, Linfeng

    1992-06-01

    This paper presents a new concept of rolling bearing stiffness in arbitrary direction, which is necessary to the investigation of rotor-bearing dynamics. It includes the axial stiffness and the arbitrary radial stiffness of the rolling bearing. Based on elasticity theory and the geometrical parameters of the bearing, the approximate formulas of the axial stiffness, the arbitrary radial stiffness, and the inner ring displacements are derived. Furthermore, the paper also discusses the effects of the loads, the radial clearance, and the load distribution parameters on the rolling bearing stiffness. In order to verify the model and the computer program, an example of a ball bearing is analyzed in detail. It shows that the model and the program are reliable and the results are consistent with the data supplied by the U.S. Air Force Aeropropulsion Laboratory.

  16. Arbitrariness, Iconicity, and Systematicity in Language.

    PubMed

    Dingemanse, Mark; Blasi, Damián E; Lupyan, Gary; Christiansen, Morten H; Monaghan, Padraic

    2015-10-01

    The notion that the form of a word bears an arbitrary relation to its meaning accounts only partly for the attested relations between form and meaning in the languages of the world. Recent research suggests a more textured view of vocabulary structure, in which arbitrariness is complemented by iconicity (aspects of form resemble aspects of meaning) and systematicity (statistical regularities in forms predict function). Experimental evidence suggests these form-to-meaning correspondences serve different functions in language processing, development, and communication: systematicity facilitates category learning by means of phonological cues, iconicity facilitates word learning and communication by means of perceptuomotor analogies, and arbitrariness facilitates meaning individuation through distinctive forms. Processes of cultural evolution help to explain how these competing motivations shape vocabulary structure.

  17. Engineering arbitrary pure and mixed quantum states

    SciTech Connect

    Pechen, Alexander

    2011-10-15

    Controlled manipulation by atomic- and molecular-scale quantum systems has attracted a lot of research attention in recent years. A fundamental problem is to provide deterministic methods for controlled engineering of arbitrary quantum states. This work proposes a deterministic method for engineering arbitrary pure and mixed states of a wide class of quantum systems. The method exploits a special combination of incoherent and coherent controls (incoherent and coherent radiation) and has two properties which are specifically important for manipulating by quantum systems: it realizes the strongest possible degree of their state control, complete density matrix controllability, meaning the ability to steer arbitrary pure and mixed initial states into any desired pure or mixed final state, and it is all-to-one, such that each particular control transfers all initial system states into one target state.

  18. Electrostatic solitary structures in the solar wind plasma

    NASA Astrophysics Data System (ADS)

    Singh, Satyavir; Singh Lakhina, Gurbax; Rubia, R.

    2016-07-01

    Recent observations have shown the existence of coherent electrostatic structures observed in the solar wind at 1 AU which could accelerate the charged particles. Electrostatic solitary waves are studied in a homogeneous, collisionless, and magnetized three-component plasma model relevant to the solar wind plasma. The theoretical model consists of hot protons, hot heavier ions (doubly charged helium ions) and suprathermal electrons having kappa distribution. Sagdeev pseudopotential technique is used to study the arbitrary amplitude ion-acoustic solitary wave. The study shows that when the heavier ion temperature is not exactly 4 times the proton temperature, we observe a new slow ion-acoustic mode in addition to the usual fast ion-acoustic mode. It is found that fast ion-acoustic mode supports only positive potential solitons. However, slow ion-acoustic mode is found to support both positive and negative potential solitons/double layers. The effect of various parameters such as the spectral index, κ, Mach number, temperature and number density of ions is studied on the evolution of ion-acoustic solitary waves as well as their existence domains. It is found that the limitation on the attainable amplitudes of fast ion-acoustic solitons is attributed to, that the number density of protons should remain real valued. While, for the slow ion-acoustic solitons the upper limit is provided by the requirement that the number density of heavier ion should remain real. In the presence of the double layers, the occurrence of the double layer limits the attainable amplitudes of the slow ion-acoustic solitons.

  19. All One-loop Maximally Helicity Violating Gluonic Amplitudes in QCD

    SciTech Connect

    Berger, Carola F.; Bern, Zvi; Dixon, Lance J.; Forde, Darren; Kosower, David A.

    2006-07-05

    We use on-shell recursion relations to compute analytically the one-loop corrections to maximally-helicity-violating n-gluon amplitudes in QCD. The cut-containing parts have been computed previously; our work supplies the remaining rational parts for these amplitudes, which contain two gluons of negative helicity and the rest positive, in an arbitrary color ordering. We also present formulae specific to the six-gluon cases, with helicities (-+-+++) and (-++-++), as well as numerical results for six, seven, and eight gluons. Our construction of the n-gluon amplitudes illustrates the relatively modest growth in complexity of the on-shell-recursive calculation as the number of external legs increases. These amplitudes add to the growing body of one-loop amplitudes known for all n, which are useful for studies of general properties of amplitudes, including their twistor-space structure.

  20. All Tree-level Amplitudes in Massless QCD

    SciTech Connect

    Dixon, Lance J.; Henn, Johannes M.; Plefka, Jan; Schuster, Theodor; /Humboldt U., Berlin

    2010-10-25

    We derive compact analytical formulae for all tree-level color-ordered gauge theory amplitudes involving any number of external gluons and up to three massless quark-anti-quark pairs. A general formula is presented based on the combinatorics of paths along a rooted tree and associated determinants. Explicit expressions are displayed for the next-to-maximally helicity violating (NMHV) and next-to-next-to-maximally helicity violating (NNMHV) gauge theory amplitudes. Our results are obtained by projecting the previously-found expressions for the super-amplitudes of the maximally supersymmetric Yang-Mills theory (N = 4 SYM) onto the relevant components yielding all gluon-gluino tree amplitudes in N = 4 SYM. We show how these results carry over to the corresponding QCD amplitudes, including massless quarks of different flavors as well as a single electroweak vector boson. The public Mathematica package GGT is described, which encodes the results of this work and yields analytical formulae for all N = 4 SYM gluon-gluino trees. These in turn yield all QCD trees with up to four external arbitrary-flavored massless quark-anti-quark-pairs.

  1. Lorentz constraints on massive three-point amplitudes

    NASA Astrophysics Data System (ADS)

    Conde, Eduardo; Marzolla, Andrea

    2016-09-01

    Using the helicity-spinor language we explore the non-perturbative constraints that Lorentz symmetry imposes on three-point amplitudes where the asymptotic states can be massive. As it is well known, in the case of only massless states the three-point amplitude is fixed up to a coupling constant by these constraints plus some physical requirements. We find that a similar statement can be made when some of the particles have mass. We derive the generic functional form of the three-point amplitude by virtue of Lorentz symmetry, which displays several functional structures accompanied by arbitrary constants. These constants can be related to the coupling constants of the theory, but in an unambiguous fashion only in the case of one massive particle. Constraints on these constants are obtained by imposing that in the UV limit the massive amplitude matches the massless one. In particular, there is a certain Lorentz frame, which corresponds to projecting all the massive momenta along the same null momentum, where the three-point massive amplitude is fully fixed, and has a universal form.

  2. Small amplitude solitons in a warm plasma with smaller and higher order relativistic effects

    SciTech Connect

    Kalita, B. C.; Das, R.

    2007-07-15

    Solitons have been investigated in a warm plasma through the Korteweg-de Vries (KdV) equation, considering a smaller relativistic effect for {gamma}{approx_equal}O(v{sup 2}/c{sup 2}) and {gamma}{sub e}{approx_equal}O(u{sup 2}/c{sup 2}) and higher relativistic effects for {gamma}{approx_equal}O(v{sup 4}/c{sup 4}) and {gamma}{sub e}{approx_equal}O(u{sup 4/}c{sup 4}). Compressive fast ion-acoustic solitons are observed to exist in the entire range (u{sub 0}-v{sub 0}) subject to a suitable mathematical condition satisfied by the initial streaming velocities u{sub 0},v{sub 0} of the electrons and the ions, respectively, electron to ion mass ratio Q(=m{sub e}/m{sub i}) and ion to electron temperature ratio {sigma}(=T{sub i}/T{sub e}). Further, rarefactive solitons of pretty small amplitudes are observed in the small upper range of |u{sub 0}-v{sub 0}| for higher order relativistic effect which are found to change parabolically. It is essentially important to report in our model of plasma, that the higher order relativistic effect slows down the soliton speed to V{<=}0.10 for all temperature ratios {sigma} for small amplitude waves. On the other hand, the smaller order relativistic effect permits the soliton to exist even at a relatively much higher speed V<0.30. Solitons of high (negligible) amplitudes are found to generate at the smaller (greater) difference of initial streamings (u{sub 0}-v{sub 0}) corresponding to both the relativistic effects.

  3. Optimization of payload placement on arbitrary spacecraft

    NASA Technical Reports Server (NTRS)

    Ferebee, Melvin J., Jr.; Allen, Cheryl L.

    1991-01-01

    A systematic method for determining the optical placement of instrumentation on an arbitrary spacecraft is described. The method maximizes the resource utilization by minimizing the spacecraft's need for propulsive attitude control. The mathematical program developed with considerations toward reducing the size of the optimization effort is presented.

  4. Teukolsky-Starobinsky identities for arbitrary spin

    NASA Astrophysics Data System (ADS)

    Kalnins, E. G.; Miller, W., Jr.; Williams, G. C.

    1989-12-01

    The Teukolsky-Starobinsky identities are proven for arbitrary spin s. A pair of covariant equations are given that admit solutions in terms of Teukolsky functions for general s. The method of proof is shown to extend to the general class of space-times considered by Torres del Castillo [J. Math. Phys. 29, 2078 (1988)].

  5. Small amplitude quasibreathers and oscillons

    SciTech Connect

    Fodor, Gyula; Lukacs, Arpad; Forgacs, Peter; Horvath, Zalan

    2008-07-15

    Quasibreathers (QB) are time-periodic solutions with weak spatial localization introduced in G. Fodor et al. in [Phys. Rev. D 74, 124003 (2006)]. QB's provide a simple description of oscillons (very long-living spatially localized time dependent solutions). The small amplitude limit of QB's is worked out in a large class of scalar theories with a general self-interaction potential, in D spatial dimensions. It is shown that the problem of small amplitude QB's is reduced to a universal elliptic partial differential equation. It is also found that there is the critical dimension, D{sub crit}=4, above which no small amplitude QB's exist. The QB's obtained this way are shown to provide very good initial data for oscillons. Thus these QB's provide the solution of the complicated, nonlinear time dependent problem of small amplitude oscillons in scalar theories.

  6. Model selection for amplitude analysis

    NASA Astrophysics Data System (ADS)

    Guegan, B.; Hardin, J.; Stevens, J.; Williams, M.

    2015-09-01

    Model complexity in amplitude analyses is often a priori under-constrained since the underlying theory permits a large number of possible amplitudes to contribute to most physical processes. The use of an overly complex model results in reduced predictive power and worse resolution on unknown parameters of interest. Therefore, it is common to reduce the complexity by removing from consideration some subset of the allowed amplitudes. This paper studies a method for limiting model complexity from the data sample itself through regularization during regression in the context of a multivariate (Dalitz-plot) analysis. The regularization technique applied greatly improves the performance. An outline of how to obtain the significance of a resonance in a multivariate amplitude analysis is also provided.

  7. Positive amplitudes in the amplituhedron

    NASA Astrophysics Data System (ADS)

    Arkani-Hamed, Nima; Hodges, Andrew; Trnka, Jaroslav

    2015-08-01

    The all-loop integrand for scattering amplitudes in planar SYM is determined by an "amplitude form" with logarithmic singularities on the boundary of the amplituhedron. In this note we provide strong evidence for a new striking property of the superamplitude, which we conjecture to be true to all loop orders: the amplitude form is positive when evaluated inside the amplituhedron. The statement is sensibly formulated thanks to the natural "bosonization" of the superamplitude associated with the amplituhedron geometry. However this positivity is not manifest in any of the current approaches to scattering amplitudes, and in particular not in the cellulations of the amplituhedron related to on-shell diagrams and the positive grassmannian. The surprising positivity of the form suggests the existence of a "dual amplituhedron" formulation where this feature would be made obvious. We also suggest that the positivity is associated with an extended picture of amplituhedron geometry, with the amplituhedron sitting inside a co-dimension one surface separating "legal" and "illegal" local singularities of the amplitude. We illustrate this in several simple examples, obtaining new expressions for amplitudes not associated with any triangulations, but following in a more invariant manner from a global view of the positive geometry.

  8. Tempo and amplitude in growth.

    PubMed

    Hermanussen, Michael

    2011-01-01

    Growth is defined as an increase of size over time with time usually defined as physical time. Yet, the rigid metric of physical time is not directly relevant to the internal dynamics of growth. Growth is linked to maturation. Children and adolescents differ in the tempo at which they mature. One calendar year differs in its meaning in a fast maturing, and in a slow maturing child. The slow child needs more calendar years for completing the same stage of maturity. Many characteristics in the human growth curve are tempo characteristics. Tempo - being fast or slow maturing - has to be carefully separated from amplitude - being tall or short. Several characteristic phenomena such as catch-up growth after periods of illness and starvation are largely tempo phenomena, and do usually not affect the amplitude component of growth. Applying Functional Data Analysis and Principal Component Analysis, the two main sources of height variance: tempo and amplitude can statistically be separate and quantified. Tempo appears to be more sensitive than amplitude to nutrition, health and environmental stress. An appropriate analysis of growth requires disentangling its two major components: amplitude and tempo. The assessment of the developmental tempo thus is an integral part of assessing child and adolescent growth. Though an Internet portal is currently available to process small amounts of height data (www.willi-will-wachsen.com) for separately determining amplitude and tempo in growth, there is urgent need of better and practical solutions for analyzing individual growth.

  9. Effect of cooler electrons on a compressive ion acoustic solitary wave in a warm ion plasma — Forbidden regions, double layers, and supersolitons

    SciTech Connect

    Ghosh, S. S.; Sekar Iyengar, A. N.

    2014-08-15

    It is observed that the presence of a minority component of cooler electrons in a three component plasma plays a deterministic role in the evolution of solitary waves, double layers, or the newly discovered structures called supersolitons. The inclusion of the cooler component of electrons in a single electron plasma produces sharp increase in nonlinearity in spite of a decrease in the overall energy of the system. The effect maximizes at certain critical value of the number density of the cooler component (typically 15%–20%) giving rise to a hump in the amplitude variation profile. For larger amplitudes, the hump leads to a forbidden region in the ambient cooler electron concentration which dissociates the overall existence domain of solitary wave solutions in two distinct parameter regime. It is observed that an inclusion of the cooler component of electrons as low as < 1% affects the plasma system significantly resulting in compressive double layers. The solution is further affected by the cold to hot electron temperature ratio. In an adequately hotter bulk plasma (i.e., moderately low cold to hot electron temperature ratio), the parameter domain of compressive double layers is bounded by a sharp discontinuity in the corresponding amplitude variation profile which may lead to supersolitons.

  10. Quantum Fidelity for Arbitrary Gaussian States

    NASA Astrophysics Data System (ADS)

    Banchi, Leonardo; Braunstein, Samuel L.; Pirandola, Stefano

    2015-12-01

    We derive a computable analytical formula for the quantum fidelity between two arbitrary multimode Gaussian states which is simply expressed in terms of their first- and second-order statistical moments. We also show how such a formula can be written in terms of symplectic invariants and used to derive closed forms for a variety of basic quantities and tools, such as the Bures metric, the quantum Fisher information, and various fidelity-based bounds. Our result can be used to extend the study of continuous-variable protocols, such as quantum teleportation and cloning, beyond the current one-mode or two-mode analyses, and paves the way to solve general problems in quantum metrology and quantum hypothesis testing with arbitrary multimode Gaussian resources.

  11. Fraunhofer diffraction by arbitrary-shaped obstacles.

    PubMed

    Malinka, Aleksey V; Zege, Eleonora P

    2009-08-01

    We consider Fraunhofer diffraction by an ensemble of large arbitrary-shaped screens that are randomly oriented in the plane of a wavefront and have edges of arbitrary shape. It is shown that far outside the main diffraction peak the differential scattering cross section behaves asymptotically as theta(-3), where theta is the diffraction angle. Moreover, the differential scattering cross section depends only on the length of the contours bordering the screens and does not depend on the shape of the obstacles. As both strictly forward and total diffraction cross sections are specified by obstacle area only, the differential cross section of size-distributed obstacles is expected to be nearly independent of obstacle shape over the entire region of the diffraction angles.

  12. The arbitrariness and normativity of social conventions.

    PubMed

    Al-Amoudi, Ismael; Latsis, John

    2014-06-01

    This paper investigates a puzzling feature of social conventions: the fact that they are both arbitrary and normative. We examine how this tension is addressed in sociological accounts of conventional phenomena. Traditional approaches tend to generate either synchronic accounts that fail to consider the arbitrariness of conventions, or diachronic accounts that miss central aspects of their normativity. As a remedy, we propose a processual conception that considers conventions as both the outcome and material cause of much human activity. This conceptualization, which borrows from the économie des conventions as well as critical realism, provides a novel perspective on how conventions are nested and defined, and on how they are established, maintained and challenged. PMID:24712730

  13. Quantum Fidelity for Arbitrary Gaussian States.

    PubMed

    Banchi, Leonardo; Braunstein, Samuel L; Pirandola, Stefano

    2015-12-31

    We derive a computable analytical formula for the quantum fidelity between two arbitrary multimode Gaussian states which is simply expressed in terms of their first- and second-order statistical moments. We also show how such a formula can be written in terms of symplectic invariants and used to derive closed forms for a variety of basic quantities and tools, such as the Bures metric, the quantum Fisher information, and various fidelity-based bounds. Our result can be used to extend the study of continuous-variable protocols, such as quantum teleportation and cloning, beyond the current one-mode or two-mode analyses, and paves the way to solve general problems in quantum metrology and quantum hypothesis testing with arbitrary multimode Gaussian resources. PMID:26764978

  14. Unsteady aerodynamic modeling for arbitrary motions

    NASA Technical Reports Server (NTRS)

    Edwards, J. W.; Ashley, H.; Breakwell, J. V.

    1977-01-01

    A study is presented on the unsteady aerodynamic loads due to arbitrary motions of a thin wing and their adaptation for the calculation of response and true stability of aeroelastic modes. In an Appendix, the use of Laplace transform techniques and the generalized Theodorsen function for two-dimensional incompressible flow is reviewed. New applications of the same approach are shown also to yield airloads valid for quite general small motions. Numerical results are given for the two-dimensional supersonic case. Previously proposed approximate methods, starting from simple harmonic unsteady theory, are evaluated by comparison with exact results obtained by the present approach. The Laplace inversion integral is employed to separate the loads into 'rational' and 'nonrational' parts, of which only the former are involved in aeroelastic stability of the wing. Among other suggestions for further work, it is explained how existing aerodynamic computer programs may be adapted in a fairly straightforward fashion to deal with arbitrary transients.

  15. General Potential Theory of Arbitrary Wing Sections

    NASA Technical Reports Server (NTRS)

    Theodorsen, T.; Garrick, I. E.

    1979-01-01

    The problem of determining the two dimensional potential flow around wing sections of any shape is examined. The problem is condensed into the compact form of an integral equation capable of yielding numerical solutions by a direct process. An attempt is made to analyze and coordinate the results of earlier studies relating to properties of wing sections. The existing approximate theory of thin wing sections and the Joukowski theory with its numerous generalizations are reduced to special cases of the general theory of arbitrary sections, permitting a clearer perspective of the entire field. The method which permits the determination of the velocity at any point of an arbitrary section and the associated lift and moments is described. The method is also discussed in terms for developing new shapes of preassigned aerodynamical properties.

  16. Arbitrary Lagrangian Eulerian Adaptive Mesh Refinement

    SciTech Connect

    Koniges, A.; Eder, D.; Masters, N.; Fisher, A.; Anderson, R.; Gunney, B.; Wang, P.; Benson, D.; Dixit, P.

    2009-09-29

    This is a simulation code involving an ALE (arbitrary Lagrangian-Eulerian) hydrocode with AMR (adaptive mesh refinement) and pluggable physics packages for material strength, heat conduction, radiation diffusion, and laser ray tracing developed a LLNL, UCSD, and Berkeley Lab. The code is an extension of the open source SAMRAI (Structured Adaptive Mesh Refinement Application Interface) code/library. The code can be used in laser facilities such as the National Ignition Facility. The code is alsi being applied to slurry flow (landslides).

  17. Multichannel 1 → 2 transition amplitudes in a finite volume

    SciTech Connect

    Briceno, Raul A.; Hansen, Maxwell T.; Walker-Loud, Andre

    2015-02-03

    We perform a model-independent, non-perturbative investigation of two-point and three-point finite-volume correlation functions in the energy regime where two-particle states can go on-shell. We study three-point functions involving a single incoming particle and an outgoing two-particle state, relevant, for example, for studies of meson decays (e.g., B⁰ → K*l⁺l⁻) or meson photo production (e.g., πγ* → ππ). We observe that, while the spectrum solely depends upon the on-shell scattering amplitude, the correlation functions also depend upon off-shell amplitudes. The main result of this work is a non-perturbative generalization of the Lellouch-Luscher formula relating matrix elements of currents in finite and infinite spatial volumes. We extend that work by considering a theory with multiple, strongly-coupled channels and by accommodating external currents which inject arbitrary four-momentum as well as arbitrary angular-momentum. The result is exact up to exponentially suppressed corrections governed by the pion mass times the box size. We also apply our master equation to various examples, including two processes mentioned above as well as examples where the final state is an admixture of two open channels.

  18. The Determination of Pseudoscalar Meson Photoproduction Amplitudes from Complete Experiments

    SciTech Connect

    A. M. Sandorfi, S. Hoblit, H. Kamano, and T-S. H. Lee

    2011-10-01

    A new generation of complete experiments is currently underway with the goal of performing a high precision extraction of pseudoscalar meson photo-production amplitudes. Here we review the most general analytic form of the cross section, dependent upon the three polarization vectors of the beam, target and recoil baryon, including all single, double and triple-polarization terms involving 16 spin-dependent observables. Analytic expressions that determine the recoil baryon polarization are also presented. Different conventions are in use in the literature and we have used a numerical calculation of cross sections from Chew-Goldberger-Low-Nambu amplitudes with arbitrary spin projections to clarify apparent sign differences. As an illustration of the use of this machinery, we carry out a multipole analysis of the gammap --> K+Lambda reaction and examine the impact of recently published polarization measurements. In fitting multipoles, we use a combined Monte Carlo sampling of the amplitude space, with gradient minimization, and find a shallow chi2 valley pitted with a very large number of local minima, despite the inclusion of recent data on 8 different observables. We conclude that, while a mathematical solution to the problem of determining an amplitude free of ambiguities may require 8 observables, as has been pointed out in the literature, experiments with realistically achievable uncertainties will require a significantly larger number.

  19. Distinguishing proteins from arbitrary amino acid sequences.

    PubMed

    Yau, Stephen S-T; Mao, Wei-Guang; Benson, Max; He, Rong Lucy

    2015-01-01

    What kinds of amino acid sequences could possibly be protein sequences? From all existing databases that we can find, known proteins are only a small fraction of all possible combinations of amino acids. Beginning with Sanger's first detailed determination of a protein sequence in 1952, previous studies have focused on describing the structure of existing protein sequences in order to construct the protein universe. No one, however, has developed a criteria for determining whether an arbitrary amino acid sequence can be a protein. Here we show that when the collection of arbitrary amino acid sequences is viewed in an appropriate geometric context, the protein sequences cluster together. This leads to a new computational test, described here, that has proved to be remarkably accurate at determining whether an arbitrary amino acid sequence can be a protein. Even more, if the results of this test indicate that the sequence can be a protein, and it is indeed a protein sequence, then its identity as a protein sequence is uniquely defined. We anticipate our computational test will be useful for those who are attempting to complete the job of discovering all proteins, or constructing the protein universe. PMID:25609314

  20. Factorization of chiral string amplitudes

    NASA Astrophysics Data System (ADS)

    Huang, Yu-tin; Siegel, Warren; Yuan, Ellis Ye

    2016-09-01

    We re-examine a closed-string model defined by altering the boundary conditions for one handedness of two-dimensional propagators in otherwise-standard string theory. We evaluate the amplitudes using Kawai-Lewellen-Tye factorization into open-string amplitudes. The only modification to standard string theory is effectively that the spacetime Minkowski metric changes overall sign in one open-string factor. This cancels all but a finite number of states: as found in earlier approaches, with enough supersymmetry (e.g., type II) the tree amplitudes reproduce those of the massless truncation of ordinary string theory. However, we now find for the other cases that additional fields, formerly thought to be auxiliary, describe new spin-2 states at the two adjacent mass levels (tachyonic and tardyonic). The tachyon is always a ghost, but can be avoided in the heterotic case.

  1. Shape of Pion Distribution Amplitude

    SciTech Connect

    Radyushkin, Anatoly

    2009-11-01

    A scenario is investigated in which the leading-twist pion distribution amplitude $\\varphi_\\pi (x)$ is approximated by the pion decay constant $f_\\pi$ for all essential values of the light-cone fraction $x$. A model for the light-front wave function $\\Psi (x, k_\\perp)$ is proposed that produces such a distribution amplitude and has a rapidly decreasing (exponential for definiteness) dependence on the light-front energy combination $ k_\\perp^2/x(1-x)$. It is shown that this model easily reproduces the fit of recent large-$Q^2$ BaBar data on the photon-pion transition form factor. Some aspects of scenario with flat pion distribution amplitude are discussed.

  2. Irreducible tensor approach to spin observables in the photoproduction of mesons with arbitrary spin-parity s{sup {pi}}

    SciTech Connect

    Ramachandran, G.; Vidya, M. S.; Balasubramanyam, J.

    2007-06-15

    A theoretical formalism leading to elegant derivation of formulas for all spin observables is outlined for photoproduction of mesons with arbitrary spin-parity s{sup {pi}}. The salient features of this formalism, based on irreducible tensor techniques, are (i) the number of independent irreducible tensor amplitudes is 4(2s+1) (ii) a single compact formula is sufficient to express these amplitudes in terms of allowed electric and magnetic multipole amplitudes, and (iii) all the spin observables, including beam analyzing powers as well as the differential cross section, are expressible in terms of bilinear irreducible tensors of rank 0 to 2(s+1). The relationship between the irreducible tensor amplitudes and the helicity amplitudes is elucidated in general and explicit expressions for the helicity amplitudes are given in terms of the irreducible tensor amplitudes in the particular cases of pseudoscalar and vector meson photoproduction. The connection between the irreducible tensor amplitudes introduced here and the well-known Chew-Goldberger-Low-Nambu amplitudes for photoproduction of pseudoscalar mesons is also established.

  3. Employing helicity amplitudes for resummation

    NASA Astrophysics Data System (ADS)

    Moult, Ian; Stewart, Iain W.; Tackmann, Frank J.; Waalewijn, Wouter J.

    2016-05-01

    Many state-of-the-art QCD calculations for multileg processes use helicity amplitudes as their fundamental ingredients. We construct a simple and easy-to-use helicity operator basis in soft-collinear effective theory (SCET), for which the hard Wilson coefficients from matching QCD onto SCET are directly given in terms of color-ordered helicity amplitudes. Using this basis allows one to seamlessly combine fixed-order helicity amplitudes at any order they are known with a resummation of higher-order logarithmic corrections. In particular, the virtual loop amplitudes can be employed in factorization theorems to make predictions for exclusive jet cross sections without the use of numerical subtraction schemes to handle real-virtual infrared cancellations. We also discuss matching onto SCET in renormalization schemes with helicities in 4- and d -dimensions. To demonstrate that our helicity operator basis is easy to use, we provide an explicit construction of the operator basis, as well as results for the hard matching coefficients, for p p →H +0 , 1, 2 jets, p p →W /Z /γ +0 , 1, 2 jets, and p p →2 , 3 jets. These operator bases are completely crossing symmetric, so the results can easily be applied to processes with e+e- and e-p collisions.

  4. Small amplitude quasibreathers and oscillons

    NASA Astrophysics Data System (ADS)

    Fodor, Gyula; Forgács, Péter; Horváth, Zalán; Lukács, Árpád

    2008-07-01

    Quasibreathers (QB) are time-periodic solutions with weak spatial localization introduced in G. Fodor et al. in [Phys. Rev. D 74, 124003 (2006)PRVDAQ0556-282110.1103/PhysRevD.74.124003]. QB’s provide a simple description of oscillons (very long-living spatially localized time dependent solutions). The small amplitude limit of QB’s is worked out in a large class of scalar theories with a general self-interaction potential, in D spatial dimensions. It is shown that the problem of small amplitude QB’s is reduced to a universal elliptic partial differential equation. It is also found that there is the critical dimension, Dcrit=4, above which no small amplitude QB’s exist. The QB’s obtained this way are shown to provide very good initial data for oscillons. Thus these QB’s provide the solution of the complicated, nonlinear time dependent problem of small amplitude oscillons in scalar theories.

  5. Toward complete pion nucleon amplitudes

    SciTech Connect

    Mathieu, Vincent; Danilkin, Igor V.; Fernández-Ramírez, Cesar; Pennington, Michael R.; Schott, Diane M.; Szczepaniak, Adam P.; Fox, G.

    2015-10-05

    We compare the low-energy partial wave analyses πN scattering with a high-energy data via finite energy sum rules. We also construct a new set of amplitudes by matching the imaginary part from the low-energy analysis with the high-energy, Regge parametrization and then reconstruct the real parts using dispersion relations.

  6. Extracting amplitudes from photoproduction data

    NASA Astrophysics Data System (ADS)

    Workman, R. L.

    2011-09-01

    We consider the problems associated with amplitude extraction, from meson photoproduction data, over the first resonance regions. The notion of a complete experiment has motivated the FROST program at Jefferson Lab. Exercises applied to pion photoproduction data illustrate the problems to be confronted in any attempt to extract underlying resonance signals from these data (without introducing a model for the resonant process).

  7. Clausius entropy for arbitrary bifurcate null surfaces

    NASA Astrophysics Data System (ADS)

    Baccetti, Valentina; Visser, Matt

    2014-02-01

    Jacobson’s thermodynamic derivation of the Einstein equations was originally applied only to local Rindler horizons. But at least some parts of that construction can usefully be extended to give meaningful results for arbitrary bifurcate null surfaces. As presaged in Jacobson’s original article, this more general construction sharply brings into focus the questions: is entropy objectively ‘real’? Or is entropy in some sense subjective and observer-dependent? These innocent questions open a Pandora’s box of often inconclusive debate. A consensus opinion, though certainly not universally held, seems to be that Clausius entropy (thermodynamic entropy, defined via a Clausius relation {\\rm{d}}S = \\unicode{x111} Q/T) should be objectively real, but that the ontological status of statistical entropy (Shannon or von Neumann entropy) is much more ambiguous, and much more likely to be observer-dependent. This question is particularly pressing when it comes to understanding Bekenstein entropy (black hole entropy). To perhaps further add to the confusion, we shall argue that even the Clausius entropy can often be observer-dependent. In the current article we shall conclusively demonstrate that one can meaningfully assign a notion of Clausius entropy to arbitrary bifurcate null surfaces—effectively defining a ‘virtual Clausius entropy’ for arbitrary ‘virtual (local) causal horizons’. As an application, we see that we can implement a version of the generalized second law (GSL) for this virtual Clausius entropy. This version of GSL can be related to certain (nonstandard) integral variants of the null energy condition. Because the concepts involved are rather subtle, we take some effort in being careful and explicit in developing our framework. In future work we will apply this construction to generalize Jacobson’s derivation of the Einstein equations.

  8. Multiboson Correlation Interferometry with Arbitrary Single-Photon Pure States.

    PubMed

    Tamma, Vincenzo; Laibacher, Simon

    2015-06-19

    We provide a compact full description of multiboson correlation measurements of arbitrary order N in passive linear interferometers with arbitrary input single-photon pure states. This allows us to physically analyze the novel problem of multiboson correlation sampling at the output of random linear interferometers. Our results also describe general multiboson correlation landscapes for an arbitrary number of input single photons and arbitrary interferometers. In particular, we use two different schemes to demonstrate, respectively, arbitrary-order quantum beat interference and 100% visibility entanglement correlations even for input photons distinguishable in their frequencies. PMID:26196976

  9. Pion-pion scattering amplitude

    SciTech Connect

    Pelaez, J.R.; Yndurain, F.J.

    2005-04-01

    We obtain reliable {pi}{pi} scattering amplitudes consistent with experimental data, both at low and high energies, and fulfilling appropriate analyticity properties. We do this by first fitting experimental low energy (s{sup 1/2}{<=}1.42 GeV) phase shifts and inelasticities with expressions that incorporate analyticity and unitarity. In particular, for the S wave with isospin 0, we discuss in detail several sets of experimental data. This provides low energy partial wave amplitudes that summarize the known experimental information. Then, we impose Regge behavior as follows from factorization and experimental data for the imaginary parts of the scattering amplitudes at higher energy, and check fulfillment of dispersion relations up to 0.925 GeV. This allows us to improve our fits. The ensuing {pi}{pi} scattering amplitudes are then shown to verify dispersion relations up to 1.42 GeV, as well as s-t-u crossing sum rules and other consistency conditions. The improved parametrizations therefore provide a reliable representation of pion-pion amplitudes with which one can test chiral perturbation theory calculations, pionium decays, or use as input for CP-violating K decays. In this respect, we find [a{sub 0}{sup (0)}-a{sub 0}{sup (2)}]{sup 2}=(0.077{+-}0.008)M{sub {pi}}{sup -2} and {delta}{sub 0}{sup (0)}(m{sub K}{sup 2})-{delta}{sub 0}{sup (2)}(m{sub K}{sup 2})=52.9{+-}1.6{sup o}.

  10. Confined systems within arbitrary enclosed surfaces

    NASA Astrophysics Data System (ADS)

    Burrows, B. L.; Cohen, M.

    2016-06-01

    A new model of electronic confinement in atoms and molecules is presented. This is based on the electronic flux J which is assumed to vanish on some notional bounding surface of arbitrary shape. J is necessarily calculated using an approximate wave-function, whose parameters are chosen to satisfy the required surface conditions. This model embraces the results of all previous calculations for which the wave-functions or their derivatives vanish on conveniently shaped surfaces, but now extends the theory to more general surfaces. Examples include one-centre hydrogen-like atoms, the valence state of Li and the two centre molecular systems {{{H}}}2+ and {{HeH}}++.

  11. Computing periodic orbits with arbitrary precision.

    PubMed

    Abad, Alberto; Barrio, Roberto; Dena, Angeles

    2011-07-01

    This paper deals with the computation of periodic orbits of dynamical systems up to any arbitrary precision. These very high requirements are useful, for example, in the studies of complex pole location in many physical systems. The algorithm is based on an optimized shooting method combined with a numerical ordinary differential equation (ODE) solver, tides, that uses a Taylor-series method. Nowadays, this methodology is the only one capable of reaching precision up to thousands of digits for ODEs. The method is shown to be quadratically convergent. Some numerical tests for the paradigmatic Lorenz model and the Hénon-Heiles Hamiltonian are presented, giving periodic orbits up to 1000 digits.

  12. Magnetooptic ellipsometry in multilayers at arbitrary magnetization.

    PubMed

    Visnovsky, S; Lopusnik, R; Bauer, M; Bok, J; Fassbender, J; Hillebrands, B

    2001-07-30

    The Yeh's 4 x 4 matrix formalism is applied to determine the electromagnetic wave response in multilayers with arbitrary magnetization. With restriction to magneto-optic (MO) effects linear in the off-diagonal permittivity tensor elements, a simplified characteristic matrix for a magnetic layer is obtained. For a magnetic film-substrate system analytical representations of the MO response expressed in terms of the Jones reflection matrix are provided. These are numerically evaluated for cases when the magnetization develops in three mutually perpendicular planes.

  13. Arbitrary Lagrangian Eulerian Adaptive Mesh Refinement

    2009-09-29

    This is a simulation code involving an ALE (arbitrary Lagrangian-Eulerian) hydrocode with AMR (adaptive mesh refinement) and pluggable physics packages for material strength, heat conduction, radiation diffusion, and laser ray tracing developed a LLNL, UCSD, and Berkeley Lab. The code is an extension of the open source SAMRAI (Structured Adaptive Mesh Refinement Application Interface) code/library. The code can be used in laser facilities such as the National Ignition Facility. The code is alsi being appliedmore » to slurry flow (landslides).« less

  14. Electron parallel closures for arbitrary collisionality

    SciTech Connect

    Ji, Jeong-Young Held, Eric D.

    2014-12-15

    Electron parallel closures for heat flow, viscosity, and friction force are expressed as kernel-weighted integrals of thermodynamic drives, the temperature gradient, relative electron-ion flow velocity, and flow-velocity gradient. Simple, fitted kernel functions are obtained for arbitrary collisionality from the 6400 moment solution and the asymptotic behavior in the collisionless limit. The fitted kernels circumvent having to solve higher order moment equations in order to close the electron fluid equations. For this reason, the electron parallel closures provide a useful and general tool for theoretical and computational models of astrophysical and laboratory plasmas.

  15. Adding control to arbitrary unknown quantum operations

    PubMed Central

    Zhou, Xiao-Qi; Ralph, Timothy C.; Kalasuwan, Pruet; Zhang, Mian; Peruzzo, Alberto; Lanyon, Benjamin P.; O'Brien, Jeremy L.

    2011-01-01

    Although quantum computers promise significant advantages, the complexity of quantum algorithms remains a major technological obstacle. We have developed and demonstrated an architecture-independent technique that simplifies adding control qubits to arbitrary quantum operations—a requirement in many quantum algorithms, simulations and metrology. The technique, which is independent of how the operation is done, does not require knowledge of what the operation is, and largely separates the problems of how to implement a quantum operation in the laboratory and how to add a control. Here, we demonstrate an entanglement-based version in a photonic system, realizing a range of different two-qubit gates with high fidelity. PMID:21811242

  16. Efficient quantum circuits for arbitrary sparse unitaries

    SciTech Connect

    Jordan, Stephen P.; Wocjan, Pawel

    2009-12-15

    Arbitrary exponentially large unitaries cannot be implemented efficiently by quantum circuits. However, we show that quantum circuits can efficiently implement any unitary provided it has at most polynomially many nonzero entries in any row or column, and these entries are efficiently computable. One can formulate a model of computation based on the composition of sparse unitaries which includes the quantum Turing machine model, the quantum circuit model, anyonic models, permutational quantum computation, and discrete time quantum walks as special cases. Thus, we obtain a simple unified proof that these models are all contained in BQP. Furthermore, our general method for implementing sparse unitaries simplifies several existing quantum algorithms.

  17. Optical 8QAM and 8PSK synthesis by cascading arbitrary 2QAM with squared QPSK.

    PubMed

    Lu, Guo-Wei; Mendinueta, José Manuel Delgado; Sakamoto, Takahide; Wada, Naoya; Kawanishi, Tetsuya

    2015-08-10

    In dynamic optical networking scenarios, it is desirable that the optical transmitter chooses the most suitable modulation format in order to achieve optimal transmission performance. Owing to the ability of switching among different modulation formats, flexible optical transmitters based on reconfigurable optical devices are becoming a key component for the implementation of future flexible optical networks. In this paper, we experimentally demonstrate a flexible 8-ary transmitter to achieve adaptive switching between 8-ary phase-shift keying (8PSK) and circular 8-ary quadrature-amplitude modulation (8QAM) through reconfiguration of two cascaded in-phase/quadrature (IQ) modulators with different driving signals and biasing conditions. An arbitrary binary quadrature-amplitude modulation (2QAM) with constant or non-constant amplitude is proposed and experimentally demonstrated using an IQ modulator. Then, optical 8PSK or 8QAM modulation formats are successfully synthesized when a standard squared QPSK modulator is cascaded with a constant-amplitude or non-constant-amplitude 2QAM, respectively.

  18. Generalized pulse equations for through-transmission evaluation of arbitrary multilayered structures

    NASA Technical Reports Server (NTRS)

    Chern, E. James; Nielsen, Hatsumi T. C.

    1990-01-01

    Generalized transit time and pulse amplitude equations were derived for modelling the ultrasonic through-transmission wave propagation of an arbitrary n-layered structure. The equations can be programmed into an expert system and used to identify and predict the through-transmission pulse signals from the critical interfaces of a multilayered structure. To test the formulas, the through transmission was measured from one- and three-layered configurations in the laboratory. The experimental measurements were compared with computer-generated data determined using the derived equations. The results verify the validity of the formulas.

  19. Quantum noise and squeezing in optical parametric oscillator with arbitrary output coupling

    NASA Technical Reports Server (NTRS)

    Prasad, Sudhakar

    1993-01-01

    The redistribution of intrinsic quantum noise in the quadratures of the field generated in a sub-threshold degenerate optical parametric oscillator exhibits interesting dependences on the individual output mirror transmittances, when they are included exactly. We present a physical picture of this problem, based on mirror boundary conditions, which is valid for arbitrary transmittances. Hence, our picture applies uniformly to all values of the cavity Q factor representing, in the opposite extremes, both perfect oscillator and amplifier configurations. Beginning with a classical second-harmonic pump, we shall generalize our analysis to the finite amplitude and phase fluctuations of the pump.

  20. Generation of arbitrary cylindrical vector beams on the higher order Poincaré sphere.

    PubMed

    Chen, Shizhen; Zhou, Xinxing; Liu, Yachao; Ling, Xiaohui; Luo, Hailu; Wen, Shuangchun

    2014-09-15

    We propose and experimentally demonstrate a novel interferometric approach to generate arbitrary cylindrical vector beams on the higher order Poincaré sphere (HOPS). Our scheme is implemented by collinear superposition of two orthogonal circular polarizations with opposite topological charges. By modifying the amplitude and phase factors of the two beams, respectively, any desired vector beams on the HOPS with high tunability can be acquired. Our research provides a convenient way to evolve the polarization states in any path on the high order Poincaré sphere. PMID:26466249

  1. Superposition of Solitons with Arbitrary Parameters for Higher-order Equations

    NASA Astrophysics Data System (ADS)

    Ankiewicz, A.; Chowdury, A.

    2016-07-01

    The way in which solitons propagate and collide is an important theme in various areas of physics. We present a systematic study of the superposition of solitons in systems governed by higher-order equations related to the nonlinear Schrödinger family. We allow for arbitrary amplitudes and relative velocities and include an infinite number of equations in our analysis of collisions and superposed solitons. The formulae we obtain can be useful in determining the influence of subtle effects like higher-order dispersion in optical fibres and small delays in the material responses to imposed impulses.

  2. Search times with arbitrary detection constraints

    NASA Astrophysics Data System (ADS)

    Campos, Daniel; Bartumeus, Frederic; Méndez, Vicenç

    2013-08-01

    Random encounters in space are central to describing diffusion-limited reactions, animal foraging, search processes, and many other situations in nature. These encounters, however, are often constrained by the capacity of the searcher to detect and/or recognize its target. This can be due to limited binding and perception abilities of the searcher or hiding and avoiding mechanisms used by the target. Hence detection failure upon passage over the target location turns the process into an n-passage problem, with n being random. Here we provide a general description of this detection problem for arbitrary dimensions and arbitrary detection constraints. The mean detection time (MDT) for a random searcher embedded in a sea of homogeneously distributed targets is obtained as a function of the target density ρ, the size domain L, and the effective detection distance a. While the scaling with ρ and L is found to be universal and equivalent to that found for the corresponding first-passage problem, the scaling of the MDT on a depends on the specific detection mechanism considered.

  3. Arbitrary Order Hierarchical Bases for Computational Electromagnetics

    SciTech Connect

    Rieben, R N; White, D; Rodrigue, G

    2002-12-20

    We present a clear and general method for constructing hierarchical vector bases of arbitrary polynomial degree for use in the finite element solution of Maxwell's equations. Hierarchical bases enable p-refinement methods, where elements in a mesh can have different degrees of approximation, to be easily implemented. This can prove to be quite useful as sections of a computational domain can be selectively refined in order to achieve a greater error tolerance without the cost of refining the entire domain. While there are hierarchical formulations of vector finite elements in publication (e.g. [1]), they are defined for tetrahedral elements only, and are not generalized for arbitrary polynomial degree. Recently, Hiptmair, motivated by the theory of exterior algebra and differential forms presented a unified mathematical framework for the construction of conforming finite element spaces [2]. In [2], both 1-form (also called H(curl)) and 2-form (also called H(div)) conforming finite element spaces and the definition of their degrees of freedom are presented. These degrees of freedom are weighted integrals where the weighting function determines the character of the bases, i.e. interpolatory, hierarchical, etc.

  4. Genus dependence of superstring amplitudes

    SciTech Connect

    Davis, Simon

    2006-11-15

    The problem of the consistency of the finiteness of the supermoduli space integral in the limit of vanishing super-fixed point distance and the genus-dependence of the integral over the super-Schottky coordinates in the fundamental region containing a neighborhood of |K{sub n}|=0 is resolved. Given a choice of the categories of isometric circles representing the integration region, the exponential form of bounds for superstring amplitudes is derived.

  5. Pulse amplitude modulated chlorophyll fluorometer

    SciTech Connect

    Greenbaum, Elias; Wu, Jie

    2015-12-29

    Chlorophyll fluorometry may be used for detecting toxins in a sample because of changes in micro algae. A portable lab on a chip ("LOAC") based chlorophyll fluorometer may be used for toxin detection and environmental monitoring. In particular, the system may include a microfluidic pulse amplitude modulated ("PAM") chlorophyll fluorometer. The LOAC PAM chlorophyll fluorometer may analyze microalgae and cyanobacteria that grow naturally in source drinking water.

  6. Effects of aberrations in vortex-beams generated with amplitude diffraction gratings

    NASA Astrophysics Data System (ADS)

    Cuartas-Vélez, Carlos; Echeverri-Chacón, Santiago; Restrepo, René

    2016-03-01

    We present a mathematical model for the generation of vortex-beams by using a square profile amplitude fork diffraction grating with arbitrary topological charge. The mathematical framework of aberrations in the forked-shape diffraction grating is analysed, and the resulting diffracted pattern is simulated. Three cases of desired distortions (aberrations) in the diffraction grating are considered, obtaining phase modulation from the amplitude grating. Experimental optical vortices are generated by using a transmission spatial light modulator, which is used as a dynamic diffraction grating, allowing us to aberrate it. We show the effect of aberrations in the experimental diffracted vortex-beams and compare it with the numerical simulation.

  7. New Method for One-Loop Scattering Amplitudes in Field Theory

    SciTech Connect

    Ossola, Giovanni

    2009-12-17

    We review the main features of the OPP method for the evaluation of one-loop amplitudes of arbitrary scattering processes. In this approach, the coefficients of the scalar integrals are extracted by means of simple algebraic equations constructed by numerically evaluating the numerator of the integrand for specific choices of the integration momentum. No analytical information on the structure of the amplitude is needed, allowing for a purely numerical, but still algebraic, implementation of the algorithm. The method works for any set of internal and/or external masses, without being limited to massless theories.

  8. Dynamic optical arbitrary waveform shaping based on cascaded optical modulators of single FBG.

    PubMed

    Chen, Jingyuan; Li, Peili

    2015-08-10

    A dynamic optical arbitrary waveform generation (O-AWG) with amplitude and phase independently controlled in optical modulators of single fiber Bragg Grating (FBG) has been proposed. This novel scheme consists of several optical modulators. In the optical modulator (O-MOD), a uniform FBG is used to filter spectral component of the input signal. The amplitude is controlled by fiber stretcher (FS) in Mach-Zehnder interference (MZI) structure through interference of two MZI arms. The phase is manipulated via the second FS in the optical modulator. This scheme is investigated by simulation. Consequently, optical pulse trains with different waveforms as well as pulse trains with nonuniform pulse intensity, pulse spacing and pulse width within each period are obtained through FSs adjustment to alter the phase shifts of signal in each O-MOD. PMID:26367920

  9. Small and arbitrary shock structures in spin 1/2 magnetohydrodynamic quantum plasma

    SciTech Connect

    Sahu, Biswajit; Choudhury, Sourav; Sinha, Anjana

    2015-02-15

    The shock structures in spin-1/2 quantum plasma, in the presence of magnetic diffusivity, are studied in the framework of the quantum magnetohydrodynamic model. Linear dispersion relation for the system is carried out analytically, and the results are plotted numerically for several values of the plasma parameters. Numerical analysis for arbitrary amplitude waves is carried out, whereas for waves of small amplitude, the reductive perturbation technique is applied to obtain the Korteweg-de Vries-Burgers equation. Both the analyses are observed to give the same qualitative picture. Most importantly, the different plasma parameters are found to play significant roles in determining the nature of the shock waves. The parametric ranges for which monotonic shock and oscillatory shock solutions are observed, are found analytically.

  10. Existence and stability of alternative ion-acoustic solitary wave solution of the combined MKdV-KdV-ZK equation in a magnetized nonthermal plasma consisting of warm adiabatic ions

    SciTech Connect

    Das, Jayasree; Bandyopadhyay, Anup; Das, K. P.

    2007-09-15

    The purpose of this paper is to present the recent work of Das et al. [J. Plasma Phys. 72, 587 (2006)] on the existence and stability of the alternative solitary wave solution of fixed width of the combined MKdV-KdV-ZK (Modified Korteweg-de Vries-Korteweg-de Vries-Zakharov-Kuznetsov) equation for the ion-acoustic wave in a magnetized nonthermal plasma consisting of warm adiabatic ions in a more generalized form. Here we derive the alternative solitary wave solution of variable width instead of fixed width of the combined MKdV-KdV-ZK equation along with the condition for its existence and find that this solution assumes the sech profile of the MKdV-ZK (Modified Korteweg-de Vries-Zakharov-Kuznetsov) equation, when the coefficient of the nonlinear term of the KdV-ZK (Korteweg-de Vries-Zakharov-Kuznetsov) equation tends to zero. The three-dimensional stability analysis of the alternative solitary wave solution of variable width of the combined MKdV-KdV-ZK equation shows that the instability condition and the first order growth rate of instability are exactly the same as those of the solitary wave solution (the sech profile) of the MKdV-ZK equation, when the coefficient of the nonlinear term of the KdV-ZK equation tends to zero.

  11. Electronic structure calculations in arbitrary electrostatic environments

    NASA Astrophysics Data System (ADS)

    Watson, Mark A.; Rappoport, Dmitrij; Lee, Elizabeth M. Y.; Olivares-Amaya, Roberto; Aspuru-Guzik, Alán

    2012-01-01

    Modeling of electronic structure of molecules in electrostatic environments is of considerable relevance for surface-enhanced spectroscopy and molecular electronics. We have developed and implemented a novel approach to the molecular electronic structure in arbitrary electrostatic environments that is compatible with standard quantum chemical methods and can be applied to medium-sized and large molecules. The scheme denoted CheESE (chemistry in electrostatic environments) is based on the description of molecular electronic structure subject to a boundary condition on the system/environment interface. Thus, it is particularly suited to study molecules on metallic surfaces. The proposed model is capable of describing both electrostatic effects near nanostructured metallic surfaces and image-charge effects. We present an implementation of the CheESE model as a library module and show example applications to neutral and negatively charged molecules.

  12. Cloning quantum entanglement in arbitrary dimensions

    SciTech Connect

    Karpov, E.; Navez, P.; Cerf, N.J.

    2005-10-15

    We have found a quantum cloning machine that optimally duplicates the entanglement of a pair of d-dimensional quantum systems prepared in an arbitrary isotropic state. It maximizes the entanglement of formation contained in the two copies of any maximally entangled input state, while preserving the separability of unentangled input states. Moreover, it cannot increase the entanglement of formation of isotropic states. For large d, the entanglement of formation of each clone tends to one-half the entanglement of the input state, which corresponds to a classical behavior. Finally, we investigate a local entanglement cloner, which yields entangled clones with one-fourth the input entanglement in the large-d limit.

  13. Fast polar decomposition of an arbitrary matrix

    NASA Technical Reports Server (NTRS)

    Higham, Nicholas J.; Schreiber, Robert S.

    1988-01-01

    The polar decomposition of an m x n matrix A of full rank, where m is greater than or equal to n, can be computed using a quadratically convergent algorithm. The algorithm is based on a Newton iteration involving a matrix inverse. With the use of a preliminary complete orthogonal decomposition the algorithm can be extended to arbitrary A. How to use the algorithm to compute the positive semi-definite square root of a Hermitian positive semi-definite matrix is described. A hybrid algorithm which adaptively switches from the matrix inversion based iteration to a matrix multiplication based iteration due to Kovarik, and to Bjorck and Bowie is formulated. The decision when to switch is made using a condition estimator. This matrix multiplication rich algorithm is shown to be more efficient on machines for which matrix multiplication can be executed 1.5 times faster than matrix inversion.

  14. Scattering amplitudes in gauge theories: progress and outlook Scattering amplitudes in gauge theories: progress and outlook

    NASA Astrophysics Data System (ADS)

    Roiban, Radu; Spradlin, Marcus; Volovich, Anastasia

    2011-11-01

    oscillator. In the much more complicated realm of four-dimensional quantum field theories, developments over the past several years have led to the extremely exciting, and already partially realized, prospect of completely solving SYM theory (at least in the planar approximation). This alone is a thrilling prospect for theorists, but the great interest in this subject stems in particular from the fact that this is not some obscure field theory but rather a gauge theory, and hence a close cousin of QCD. As reviewed in several of the articles in this issue, many of the insights and methods developed for SYM theory can be applied, with suitable care, to arbitrary gauge theories. It has occasionally been noted that the study of amplitudes is an experimental science in which expressions for, or empirically observed properties of, various scattering amplitudes serve as the 'data' to be collected and analyzed. The rapid pace of progress is made possible in part by the fact that new data is often available at the click of a mouse. The articles in this issue offer testament to the riches which have been discovered hiding in these data, and there is no doubt that more rewards await theorists with the ambition to seek them out.

  15. Nonlinear saturation amplitude of cylindrical Rayleigh—Taylor instability

    NASA Astrophysics Data System (ADS)

    Liu, Wan-Hai; Yu, Chang-Ping; Ye, Wen-Hua; Wang, Li-Feng

    2014-09-01

    The nonlinear saturation amplitude (NSA) of the fundamental mode in the classical Rayleigh—Taylor instability with a cylindrical geometry for an arbitrary Atwood number is analytically investigated by considering the nonlinear corrections up to the third order. The analytic results indicate that the effects of the initial radius of the interface (r0) and the Atwood number (A) play an important role in the NSA of the fundamental mode. The NSA of the fundamental mode first increases gently and then decreases quickly with increasing A. For a given A, the smaller the r0/λ (λ is the perturbation wavelength), the larger the NSA of the fundamental mode. When r0/λ is large enough (r0 ≫ λ), the NSA of the fundamental mode is reduced to the prediction in the previous literatures within the framework of the third-order perturbation theory.

  16. Generalization of the optical theorem for monochromatic electromagnetic beams of arbitrary wavefront in cylindrical coordinates

    NASA Astrophysics Data System (ADS)

    Mitri, F. G.

    2015-11-01

    The optical theorem constitutes of the fundamental theorems in optical, acoustical, quantum, and gravitational wave scattering, which relates the extinction cross-section to the forward scattering complex amplitude function of plane waves. In this analysis, a generalized formalism is presented for beams of arbitrary character in cylindrical coordinates without restriction to the plane wave case of the angles of incidence and scattering. Based on the partial-wave series expansion method of cylindrical multipole, analytical expressions for the extinction, absorption, scattering cross-sections and efficiency factors are derived for an object of arbitrary shape. An "interference scattering" term arises in the cross-section (or efficiency), which describes the mutual interference between the diffracted or specularly reflected waves. Examples for plane waves and 2D scalar quasi-Gaussian focused beams are also considered, which illustrate the theory. The generalized optical theorem in cylindrical coordinates can be applied to evaluate the extinction efficiency from any object of arbitrary geometry placed on or off the axis of the incident beam. Applications in the context of wave scattering theory by a single particle or multiple particles would benefit from the results of the present study, in addition to other phenomena such as the radiation force and torque.

  17. Spatial shaping for generating arbitrary optical dipole traps for ultracold degenerate gases

    SciTech Connect

    Lee, Jeffrey G.; Hill, W. T.

    2014-10-15

    We present two spatial-shaping approaches – phase and amplitude – for creating two-dimensional optical dipole potentials for ultracold neutral atoms. When combined with an attractive or repulsive Gaussian sheet formed by an astigmatically focused beam, atoms are trapped in three dimensions resulting in planar confinement with an arbitrary network of potentials – a free-space atom chip. The first approach utilizes an adaptation of the generalized phase-contrast technique to convert a phase structure embedded in a beam after traversing a phase mask, to an identical intensity profile in the image plane. Phase masks, and a requisite phase-contrast filter, can be chemically etched into optical material (e.g., fused silica) or implemented with spatial light modulators; etching provides the highest quality while spatial light modulators enable prototyping and realtime structure modification. This approach was demonstrated on an ensemble of thermal atoms. Amplitude shaping is possible when the potential structure is made as an opaque mask in the path of a dipole trap beam, followed by imaging the shadow onto the plane of the atoms. While much more lossy, this very simple and inexpensive approach can produce dipole potentials suitable for containing degenerate gases. High-quality amplitude masks can be produced with standard photolithography techniques. Amplitude shaping was demonstrated on a Bose-Einstein condensate.

  18. Spatial shaping for generating arbitrary optical dipole traps for ultracold degenerate gases

    NASA Astrophysics Data System (ADS)

    Lee, Jeffrey G.; Hill, W. T.

    2014-10-01

    We present two spatial-shaping approaches - phase and amplitude - for creating two-dimensional optical dipole potentials for ultracold neutral atoms. When combined with an attractive or repulsive Gaussian sheet formed by an astigmatically focused beam, atoms are trapped in three dimensions resulting in planar confinement with an arbitrary network of potentials - a free-space atom chip. The first approach utilizes an adaptation of the generalized phase-contrast technique to convert a phase structure embedded in a beam after traversing a phase mask, to an identical intensity profile in the image plane. Phase masks, and a requisite phase-contrast filter, can be chemically etched into optical material (e.g., fused silica) or implemented with spatial light modulators; etching provides the highest quality while spatial light modulators enable prototyping and realtime structure modification. This approach was demonstrated on an ensemble of thermal atoms. Amplitude shaping is possible when the potential structure is made as an opaque mask in the path of a dipole trap beam, followed by imaging the shadow onto the plane of the atoms. While much more lossy, this very simple and inexpensive approach can produce dipole potentials suitable for containing degenerate gases. High-quality amplitude masks can be produced with standard photolithography techniques. Amplitude shaping was demonstrated on a Bose-Einstein condensate.

  19. Online tracking of instantaneous frequency and amplitude of dynamical system response

    NASA Astrophysics Data System (ADS)

    Frank Pai, P.

    2010-05-01

    This paper presents a sliding-window tracking (SWT) method for accurate tracking of the instantaneous frequency and amplitude of arbitrary dynamic response by processing only three (or more) most recent data points. Teager-Kaiser algorithm (TKA) is a well-known four-point method for online tracking of frequency and amplitude. Because finite difference is used in TKA, its accuracy is easily destroyed by measurement and/or signal-processing noise. Moreover, because TKA assumes the processed signal to be a pure harmonic, any moving average in the signal can destroy the accuracy of TKA. On the other hand, because SWT uses a constant and a pair of windowed regular harmonics to fit the data and estimate the instantaneous frequency and amplitude, the influence of any moving average is eliminated. Moreover, noise filtering is an implicit capability of SWT when more than three data points are used, and this capability increases with the number of processed data points. To compare the accuracy of SWT and TKA, Hilbert-Huang transform is used to extract accurate time-varying frequencies and amplitudes by processing the whole data set without assuming the signal to be harmonic. Frequency and amplitude trackings of different amplitude- and frequency-modulated signals, vibrato in music, and nonlinear stationary and non-stationary dynamic signals are studied. Results show that SWT is more accurate, robust, and versatile than TKA for online tracking of frequency and amplitude.

  20. Constructing Amplitudes from Their Soft Limits

    SciTech Connect

    Boucher-Veronneau, Camille; Larkoski, Andrew J.; /SLAC

    2011-12-09

    The existence of universal soft limits for gauge-theory and gravity amplitudes has been known for a long time. The properties of the soft limits have been exploited in numerous ways; in particular for relating an n-point amplitude to an (n-1)-point amplitude by removing a soft particle. Recently, a procedure called inverse soft was developed by which 'soft' particles can be systematically added to an amplitude to construct a higher-point amplitude for generic kinematics. We review this procedure and relate it to Britto-Cachazo-Feng-Witten recursion. We show that all tree-level amplitudes in gauge theory and gravity up through seven points can be constructed in this way, as well as certain classes of NMHV gauge-theory amplitudes with any number of external legs. This provides us with a systematic procedure for constructing amplitudes solely from their soft limits.

  1. Large Amplitude Oscillations in Prominences

    NASA Astrophysics Data System (ADS)

    Luna, Manuel

    2016-07-01

    Large-amplitude Oscillations in prominences are spectacular manifestations of the solar activity. In such events nearby energetic disturbances induce periodic motions on filaments with displacements comparable to the size of the filaments themselves and with velocities larger than 20 km/s. Recent studies have shown that such oscillations open a new window on coronal connectivity, as well as novel diagnostics for hard-to-measure prominence properties such as magnetic field strength and geometry. In addition, this oscillation could be related with activation of filaments prior to eruptions. In this talk I will show past and current research on this subject in order to understand the nature of the solar prominences. Additionally, a large catalogue of such events will be presented.

  2. Bell's theorem on arbitrary causal structures

    NASA Astrophysics Data System (ADS)

    Fritz, Tobias

    2014-03-01

    Bell's theorem is a gedankenexperiment with an underlying causal structure in the form of the letter ``M.'' I will describe how such a Bell scenario is a special case of a vastly larger class of scenarios, in which the causal structure of the ``M'' is replaced by an arbitrary directed acyclic graph (or, equivalently, by a causal set). In this formalism, the apparent difference between the notions of ``choice of setting,'' ``source,'' and ``measurement'' disappears completely and all of these become special cases of the general notion of ``event.'' I will explain how this relieves Bell's theorem of the philosophical baggage associated with free will and also present several mathematical results about these more general scenarios obtained by various people. This formalism is expected to have applications in many other areas of science: it is relevant whenever a system is probed at certain points in space and time, and at each of these points there may be hidden information not observed by the probes.

  3. Solving Nonlinear Euler Equations with Arbitrary Accuracy

    NASA Technical Reports Server (NTRS)

    Dyson, Rodger W.

    2005-01-01

    A computer program that efficiently solves the time-dependent, nonlinear Euler equations in two dimensions to an arbitrarily high order of accuracy has been developed. The program implements a modified form of a prior arbitrary- accuracy simulation algorithm that is a member of the class of algorithms known in the art as modified expansion solution approximation (MESA) schemes. Whereas millions of lines of code were needed to implement the prior MESA algorithm, it is possible to implement the present MESA algorithm by use of one or a few pages of Fortran code, the exact amount depending on the specific application. The ability to solve the Euler equations to arbitrarily high accuracy is especially beneficial in simulations of aeroacoustic effects in settings in which fully nonlinear behavior is expected - for example, at stagnation points of fan blades, where linearizing assumptions break down. At these locations, it is necessary to solve the full nonlinear Euler equations, and inasmuch as the acoustical energy is of the order of 4 to 5 orders of magnitude below that of the mean flow, it is necessary to achieve an overall fractional error of less than 10-6 in order to faithfully simulate entropy, vortical, and acoustical waves.

  4. Competitive epidemic spreading over arbitrary multilayer networks

    NASA Astrophysics Data System (ADS)

    Darabi Sahneh, Faryad; Scoglio, Caterina

    2014-06-01

    This study extends the Susceptible-Infected-Susceptible (SIS) epidemic model for single-virus propagation over an arbitrary graph to an Susceptible-Infected by virus 1-Susceptible-Infected by virus 2-Susceptible (SI1SI2S) epidemic model of two exclusive, competitive viruses over a two-layer network with generic structure, where network layers represent the distinct transmission routes of the viruses. We find analytical expressions determining extinction, coexistence, and absolute dominance of the viruses after we introduce the concepts of survival threshold and absolute-dominance threshold. The main outcome of our analysis is the discovery and proof of a region for long-term coexistence of competitive viruses in nontrivial multilayer networks. We show coexistence is impossible if network layers are identical yet possible if network layers are distinct. Not only do we rigorously prove a region of coexistence, but we can quantitate it via interrelation of central nodes across the network layers. Little to no overlapping of the layers' central nodes is the key determinant of coexistence. For example, we show both analytically and numerically that positive correlation of network layers makes it difficult for a virus to survive, while in a network with negatively correlated layers, survival is easier, but total removal of the other virus is more difficult.

  5. Competitive epidemic spreading over arbitrary multilayer networks.

    PubMed

    Darabi Sahneh, Faryad; Scoglio, Caterina

    2014-06-01

    This study extends the Susceptible-Infected-Susceptible (SIS) epidemic model for single-virus propagation over an arbitrary graph to an Susceptible-Infected by virus 1-Susceptible-Infected by virus 2-Susceptible (SI_{1}SI_{2}S) epidemic model of two exclusive, competitive viruses over a two-layer network with generic structure, where network layers represent the distinct transmission routes of the viruses. We find analytical expressions determining extinction, coexistence, and absolute dominance of the viruses after we introduce the concepts of survival threshold and absolute-dominance threshold. The main outcome of our analysis is the discovery and proof of a region for long-term coexistence of competitive viruses in nontrivial multilayer networks. We show coexistence is impossible if network layers are identical yet possible if network layers are distinct. Not only do we rigorously prove a region of coexistence, but we can quantitate it via interrelation of central nodes across the network layers. Little to no overlapping of the layers' central nodes is the key determinant of coexistence. For example, we show both analytically and numerically that positive correlation of network layers makes it difficult for a virus to survive, while in a network with negatively correlated layers, survival is easier, but total removal of the other virus is more difficult.

  6. Regulation of ion drifts and anisotropies by parametrically unstable finite-amplitude Alfvén-cyclotron waves in the fast solar wind

    SciTech Connect

    Maneva, Y. G.; Araneda, J. A.; Marsch, E.

    2014-03-10

    We study the preferential heating and differential acceleration of minor ions by dissipation of ion-acoustic waves (IAWs) generated by parametric instabilities of a finite-amplitude monochromatic Alfvén-cyclotron pump wave. We consider the associated kinetic effects of Landau damping and nonlinear pitch-angle scattering of protons and α particles in the tenuous plasma of coronal holes and the fast solar wind. Various data collected by Wind spacecraft show signatures for a local transverse heating of the minor ions, presumably by Alfvén-cyclotron wave dissipation, and an unexpected parallel heating by a so far unknown mechanism. Here, we present the results from a set of 1.5 dimensional hybrid simulations in search for a plausible explanation for the observed field-aligned kinetic features in the fast solar wind minor ions. We investigate the origin and regulation of ion relative drifts and temperature anisotropies in low plasma β, fast solar wind conditions. Depending on their initial drifts, both ion species can heat up not only transversely through cyclotron resonance and non-resonant wave-particle interactions, but also strongly in the parallel direction by Landau damping of the daughter IAWs. We discuss the dependence of the relative ion drifts and temperature anisotropies on the plasma β of the individual species and we describe the effect of the pump wave amplitude on the ion heating and acceleration.

  7. Quantum Szilard engines with arbitrary spin.

    PubMed

    Zhuang, Zekun; Liang, Shi-Dong

    2014-11-01

    The quantum Szilard engine (QSZE) is a conceptual quantum engine for understanding the fundamental physics of quantum thermodynamics and information physics. We generalize the QSZE to an arbitrary spin case, i.e., a spin QSZE (SQSZE), and we systematically study the basic physical properties of both fermion and boson SQSZEs in a low-temperature approximation. We give the analytic formulation of the total work. For the fermion SQSZE, the work might be absorbed from the environment, and the change rate of the work with temperature exhibits periodicity and even-odd oscillation, which is a generalization of a spinless QSZE. It is interesting that the average absorbed work oscillates regularly and periodically in a large-number limit, which implies that the average absorbed work in a fermion SQSZE is neither an intensive quantity nor an extensive quantity. The phase diagrams of both fermion and boson SQSZEs give the SQSZE doing positive or negative work in the parameter space of the temperature and the particle number of the system, but they have different behaviors because the spin degrees of the fermion and the boson play different roles in their configuration states and corresponding statistical properties. The critical temperature of phase transition depends sensitively on the particle number. By using Landauer's erasure principle, we give the erasure work in a thermodynamic cycle, and we define an efficiency (we refer to it as information-work efficiency) to measure the engine's ability of utilizing information to extract work. We also give the conditions under which the maximum extracted work and highest information-work efficiencies for fermion and boson SQSZEs can be achieved.

  8. Arbitrary Shape Deformation in CFD Design

    NASA Technical Reports Server (NTRS)

    Landon, Mark; Perry, Ernest

    2014-01-01

    Sculptor(R) is a commercially available software tool, based on an Arbitrary Shape Design (ASD), which allows the user to perform shape optimization for computational fluid dynamics (CFD) design. The developed software tool provides important advances in the state-of-the-art of automatic CFD shape deformations and optimization software. CFD is an analysis tool that is used by engineering designers to help gain a greater understanding of the fluid flow phenomena involved in the components being designed. The next step in the engineering design process is to then modify, the design to improve the components' performance. This step has traditionally been performed manually via trial and error. Two major problems that have, in the past, hindered the development of an automated CFD shape optimization are (1) inadequate shape parameterization algorithms, and (2) inadequate algorithms for CFD grid modification. The ASD that has been developed as part of the Sculptor(R) software tool is a major advancement in solving these two issues. First, the ASD allows the CFD designer to freely create his own shape parameters, thereby eliminating the restriction of only being able to use the CAD model parameters. Then, the software performs a smooth volumetric deformation, which eliminates the extremely costly process of having to remesh the grid for every shape change (which is how this process had previously been achieved). Sculptor(R) can be used to optimize shapes for aerodynamic and structural design of spacecraft, aircraft, watercraft, ducts, and other objects that affect and are affected by flows of fluids and heat. Sculptor(R) makes it possible to perform, in real time, a design change that would manually take hours or days if remeshing were needed.

  9. Determining pseudoscalar meson photoproduction amplitudes from complete experiments

    NASA Astrophysics Data System (ADS)

    Sandorfi, A. M.; Hoblit, S.; Kamano, H.; Lee, T.-S. H.

    2011-05-01

    A new generation of complete experiments is focused on a high precision extraction of pseudoscalar meson photoproduction amplitudes. Here, we review the development of the most general analytic form of the cross section, dependent upon the three polarization vectors of the beam, target and recoil baryon, including all single-, double- and triple-polarization terms involving 16 spin-dependent observables. We examine the different conventions that have been used by different authors, and we present expressions that allow the direct numerical calculation of any pseudoscalar meson photoproduction observables with arbitrary spin projections from the Chew-Goldberger-Low-Nambu amplitudes. We use this numerical tool to clarify apparent sign differences that exist in the literature, in particular with the definitions of six double-polarization observables. We also present analytic expressions that determine the recoil baryon polarization, together with examples of their potential use with quasi-4π detectors to deduce observables. As an illustration of the use of the consistent machinery presented in this review, we carry out a multipole analysis of the γp → K+Λ reaction and examine the impact of recently published polarization measurements. When combining data from different experiments, we utilize the Fierz identities to fit a consistent set of scales. In fitting multipoles, we use a combined Monte Carlo sampling of the amplitude space, with gradient minimization, and find a shallow χ2 valley pitted with a very large number of local minima. This results in broad bands of multipole solutions that are experimentally indistinguishable. While these bands have been noticeably narrowed by the inclusion of new polarization measurements, many of the multipoles remain very poorly determined, even in sign, despite the inclusion of data on eight different observables. We have compared multipoles from recent PWA codes with our model-independent solution bands and found that such

  10. Determining pseudoscalar meson photoproduction amplitudes from complete experiments

    SciTech Connect

    Sandorfi, A.M.; Hoblit, S.; Sandorfi,A.M.; Hoblit,S.; Kamano,H.; Lee,T-S.H.

    2011-04-06

    A new generation of complete experiments is focused on a high precision extraction of pseudoscalar meson photoproduction amplitudes. Here, we review the development of the most general analytic form of the cross section, dependent upon the three polarization vectors of the beam, target and recoil baryon, including all single-, double- and triple-polarization terms involving 16 spin-dependent observables. We examine the different conventions that have been used by different authors, and we present expressions that allow the direct numerical calculation of any pseudoscalar meson photoproduction observables with arbitrary spin projections from the Chew-Goldberger-Low-Nambu amplitudes. We use this numerical tool to clarify apparent sign differences that exist in the literature, in particular with the definitions of six double-polarization observables. We also present analytic expressions that determine the recoil baryon polarization, together with examples of their potential use with quasi-4{pi} detectors to deduce observables. As an illustration of the use of the consistent machinery presented in this review, we carry out a multipole analysis of the {gamma}p {yields} K{sup +}{Lambda} reaction and examine the impact of recently published polarization measurements. When combining data from different experiments, we utilize the Fierz identities to fit a consistent set of scales. In fitting multipoles, we use a combined Monte Carlo sampling of the amplitude space, with gradient minimization, and find a shallow {chi}{sup 2} valley pitted with a very large number of local minima. This results in broad bands of multipole solutions that are experimentally indistinguishable. While these bands have been noticeably narrowed by the inclusion of new polarization measurements, many of the multipoles remain very poorly determined, even in sign, despite the inclusion of data on eight different observables. We have compared multipoles from recent PWA codes with our model

  11. Numerical studies of the ABJM theory for arbitrary N at arbitrary coupling constant

    NASA Astrophysics Data System (ADS)

    Hanada, Masanori; Honda, Masazumi; Honma, Yoshinori; Nishimura, Jun; Shiba, Shotaro; Yoshida, Yutaka

    2012-05-01

    We show that the ABJM theory, which is an {N} = {6} superconformal U( N) × U( N) Chern-Simons gauge theory, can be studied for arbitrary N at arbitrary coupling constant by applying a simple Monte Carlo method to the matrix model that can be derived from the theory by using the localization technique. This opens up the possibility of probing the quantum aspects of M-theory and testing the AdS4/CFT3 duality at the quantum level. Here we calculate the free energy, and confirm the N 3/2 scaling in the M-theory limit predicted from the gravity side. We also find that our results nicely interpolate the analytical formulae proposed previously in the M-theory and type IIA regimes. Furthermore, we show that some results obtained by the Fermi gas approach can be clearly understood from the constant map contribution obtained by the genus expansion. The method can be easily generalized to the calculations of BPS operators and to other theories that reduce to matrix models.

  12. Microwave beam power transmission at an arbitrary range

    NASA Technical Reports Server (NTRS)

    Pinero, L. R.; Christian, J. L., Jr.; Acosta, R. J.

    1992-01-01

    The power transfer efficiency between two circular apertures at an arbitrary range is obtained numerically. The apertures can have generally different sizes and arbitrary taper illuminations. The effects of distance and taper illumination on the transmission efficiency are investigated for equal size apertures. The result shows that microwave beam power is more effective at close ranges, namely distances less than 2D(exp 2)/lambda. Also shown was the power transfer efficiency increase with taper illumination for close range distances. A computer program was developed for calculating the power transfer efficiency at an arbitrary range.

  13. Conformal array design on arbitrary polygon surface with transformation optics

    NASA Astrophysics Data System (ADS)

    Deng, Li; Wu, Yongle; Hong, Weijun; Zhu, Jianfeng; Peng, Biao; Li, Shufang

    2016-06-01

    A transformation-optics based method to design a conformal antenna array on an arbitrary polygon surface is proposed and demonstrated in this paper. This conformal antenna array can be adjusted to behave equivalently as a uniformly spaced linear array by applying an appropriate transformation medium. An typical example of general arbitrary polygon conformal arrays, not limited to circular array, is presented, verifying the proposed approach. In summary, the novel arbitrary polygon surface conformal array can be utilized in array synthesis and beam-forming, maintaining all benefits of linear array.

  14. Stress compensation for arbitrary curvature control in vanadium dioxide phase transition actuators

    NASA Astrophysics Data System (ADS)

    Dong, Kaichen; Lou, Shuai; Choe, Hwan Sung; Liu, Kai; You, Zheng; Yao, Jie; Wu, Junqiao

    2016-07-01

    Due to its thermally driven structural phase transition, vanadium dioxide (VO2) has emerged as a promising material for micro/nano-actuators with superior volumetric work density, actuation amplitude, and repetition frequency. However, the high initial curvature of VO2 actuators severely obstructs the actuation performance and application. Here, we introduce a "seesaw" method of fabricating tri-layer cantilevers to compensate for the residual stress and realize nearly arbitrary curvature control of VO2 actuators. By simply adjusting the thicknesses of the individual layers, cantilevers with positive, zero, or negative curvatures can be engineered. The actuation amplitude can be decoupled from the curvature and controlled independently as well. Based on the experimentally measured residual stresses, we demonstrate sub-micron thick VO2 actuators with nearly zero final curvature and a high actuation amplitude simultaneously. This "seesaw" method can be further extended to the curvature engineering of other microelectromechanical system multi-layer structures where large stress-mismatch between layers are inevitable.

  15. Successive Resonances for Ion Ejection at Arbitrary Frequencies in an Ion Trap

    NASA Astrophysics Data System (ADS)

    Snyder, Dalton T.; Cooks, R. Graham

    2016-09-01

    The use of successive resonances for ion ejection is demonstrated here as a method of scanning quadrupole ion traps with improvement in both resolution and sensitivity compared with single frequency resonance ejection. The conventional single frequency resonance ejection waveform is replaced with a dual-frequency waveform. The two included frequencies are spaced very closely and their relative amplitudes are adjusted so that the first frequency that ions encounter excites them to higher amplitudes where space charge effects are less prominent, thereby giving faster and more efficient ejection when the ions come into resonance with the second frequency. The method is applicable at any arbitrary frequency, unlike double and triple resonance methods. However, like double and triple resonance ejection, ejection using successive resonances requires the rf and AC waveforms to be phase-locked in order to retain mass accuracy and mass precision. The improved performance is seen in mass spectra acquired by rf amplitude scans (resonance ejection) as well as by secular frequency scans.

  16. Existence domains of electrostatic solitary structures in the solar wind plasma

    NASA Astrophysics Data System (ADS)

    Rubia, R.; Singh, S. V.; Lakhina, G. S.

    2016-06-01

    Electrostatic solitary waves and double layers are explored in a homogeneous, collisionless, and magnetized three-component plasma composed of hot protons, hot heavier ions (alpha particles, H e + + ), and suprathermal electrons with kappa distribution. The Sagdeev pseudopotential technique is used to study the arbitrary amplitude ion-acoustic solitons and double layers. The effect of various parameters such as the number density of ions, n i 0 ; the spectral index, κ; the Mach numbers, M; and the temperature ratio of ion to the electron σi on the evolution of ion-acoustic solitary waves as well as their existence domains is studied. The transition in the existence domain for slow-ion acoustic solitons from negative solitons/double layers to positive solitons/double layers is found to occur with a variation of the heavier ion temperature. It is observed that the width of the negative potential solitons increases as the amplitude increases, whereas for the positive potential solitons, the width decreases as the amplitude increases. Furthermore, it is found that the limitation on the attainable amplitudes of fast ion-acoustic solitons is attributed to that the number density of protons should remain real valued, while for the slow ion-acoustic solitons, the upper limit is provided by the requirement that the number density of heavier ions should remain real. In the presence of a double layer, the occurrence of the double layer limits the attainable amplitudes of the slow ion-acoustic solitons. The proposed plasma model is relevant to the coherent electrostatic structures observed in the solar wind at 1 AU.

  17. Amplitude-dependent station magnitude

    NASA Astrophysics Data System (ADS)

    Radzyner, Yael; Ben Horin, Yochai; Steinberg, David M.

    2016-04-01

    Magnitude, a concept first presented by Gutenberg and Richter, adjusts measurements of ground motion for epicentral distance and source depth. Following this principle, the IDC defines the j'th station body wave magnitude for event i as mb(stai,j) = log 10(Aj,i/Tj,i) + V C(Δj,i,hi) , where VC is the Veith-Clawson (VC) correction to compensate for the epicentral distance of the station and the depth of the source. The network magnitude is calculated as the average of station magnitudes. The IDC magnitude estimation is used for event characterization and discrimination and it should be as accurate as possible. Ideally, the network magnitude should be close in value to the station magnitudes. In reality, it is observed that the residuals range between -1 and 1 mu or ±25% of a given mb(neti) value. We show that the residual, mb(neti) -mb(staj,i), depends linearly on log 10(Aj,i/Tj,i), and we correct for this dependence using the following procedure: Calculate a "jackknifed" network magnitude, mbj,n(neti), i.e. an average over all participating stations except station n. Using all measurements at station n, calculate the parameters an, bn of the linear fit of the residual mbj,n(neti) - mb(stan,i to log 10(An,i/Tn,i). For each event i at station n calculate the new station magnitude mbnew(stan,i) = (an + 1)log(An,i/Tn,i) + V C(Δn,i,hi) + bn Calculate the new network magnitude: mbnew(neti) = 1N- ∑ n=1nmbnew(stan,i) The procedure was used on more than two million station-event pairs. Correcting for the station-specific dependence on log amplitude reduces the residuals by roughly a third. We have calculated the spread of the distributions, and compared the original values and those for the corrected magnitudes. The spread is the ratio between the variance of the network magnitudes, and the variance of the residual. Calculations show an increase in the ratio of the variance, meaning that the correction process presented in this document did not lead to loss of variance

  18. Gravity and Yang-Mills amplitude relations

    SciTech Connect

    Bjerrum-Bohr, N. E. J.; Damgaard, Poul H.; Soendergaard, Thomas; FengBo

    2010-11-15

    Using only general features of the S matrix and quantum field theory, we prove by induction the Kawai-Lewellen-Tye relations that link products of gauge theory amplitudes to gravity amplitudes at tree level. As a bonus of our analysis, we provide a novel and more symmetric form of these relations. We also establish an infinite tower of new identities between amplitudes in gauge theories.

  19. Minimal Basis for Gauge Theory Amplitudes

    SciTech Connect

    Bjerrum-Bohr, N. E. J.; Damgaard, Poul H.; Vanhove, Pierre

    2009-10-16

    Identities based on monodromy for integrations in string theory are used to derive relations between different color-ordered tree-level amplitudes in both bosonic and supersymmetric string theory. These relations imply that the color-ordered tree-level n-point gauge theory amplitudes can be expanded in a minimal basis of (n-3)exclamation amplitudes. This result holds for any choice of polarizations of the external states and in any number of dimensions.

  20. Discontinuities of multi-Regge amplitudes

    NASA Astrophysics Data System (ADS)

    Fadin, V. S.

    2015-04-01

    In the BFKL approach, discontinuities of multiple production amplitudes in invariant masses of produced particles are discussed. It turns out that they are in evident contradiction with the BDS ansatz for n-gluon amplitudes in the planar N = 4 SYM at n ≥ 6. An explicit expression for the NLO discontinuity of the two-to-four amplitude in the invariant mass of two produced gluons is is presented.

  1. Closed description of arbitrariness in resolving quantum master equation

    NASA Astrophysics Data System (ADS)

    Batalin, Igor A.; Lavrov, Peter M.

    2016-07-01

    In the most general case of the Delta exact operator valued generators constructed of an arbitrary Fermion operator, we present a closed solution for the transformed master action in terms of the original master action in the closed form of the corresponding path integral. We show in detail how that path integral reduces to the known result in the case of being the Delta exact generators constructed of an arbitrary Fermion function.

  2. Structure of the Small Amplitude Motion on Transversely Sheared Mean Flows

    NASA Technical Reports Server (NTRS)

    Goldstein, Marvin E.; Afsar, Mohamed Z.; Leib, Stewart J.

    2013-01-01

    This paper considers the small amplitude unsteady motion of an inviscid non-heat conducting compressible fluid on a transversely sheared mean flow. It extends a previous result given in Goldstein (1978(b) and 1979(a)) which shows that the hydrodynamic component of the motion is determined by two arbitrary convected quantities in the absence of solid surfaces or other external sources. The result is important because it can be used to specify appropriate boundary conditions for unsteady surface interaction problems on transversely sheared mean flows in the same way that the vortical component of the Kovasznay (1953) decomposition is used to specify these conditions for surface interaction problems on uniform mean flows. But unlike the Kovasznay (1953) case the arbitrary convected quantities no longer bear a simple relation to the physical variables. One purpose of this paper is to derive a formula that relates these quantities to the (physically measurable) vorticity and pressure fluctuations in the flow.

  3. Extended optical theorem for scalar monochromatic acoustical beams of arbitrary wavefront in cylindrical coordinates.

    PubMed

    Mitri, F G

    2016-04-01

    One of the fundamental theorems in (optical, acoustical, quantum, gravitational) wave scattering is the optical theorem for plane waves, which relates the extinction cross-section to the forward scattering complex amplitude function. In this analysis, the optical theorem is extended for the case of 3D-beams of arbitrary character in a cylindrical coordinates system for any angle of incidence and any scattering angle. Generalized analytical expressions for the extinction, absorption, scattering cross-sections and efficiency factors are derived in the framework of the scalar resonance scattering theory for an object of arbitrary shape. The analysis reveals the presence of an interference scattering cross-section term, which describes interference between the diffracted or specularly reflected inelastic (Franz) waves with the resonance elastic waves. Moreover, an alternate expression for the extinction cross-section, which relates the resonance cross-section with the scattering cross-section for an impenetrable object, is obtained, suggesting an improved method for particle characterization. Cross-section expressions are also derived for known acoustical wavefronts centered on the object, defined as the on-axis case. The extended optical theorem in cylindrical coordinates can be applied to evaluate the extinction efficiency from any object of arbitrary geometry placed on or off the axis of the incident beam. Applications in acoustics, optics, and quantum mechanics should benefit from this analysis in the context of wave scattering theory and other phenomena closely connected to it, such as the multiple scattering by many particles, as well as the radiation force and torque.

  4. Extended optical theorem for scalar monochromatic acoustical beams of arbitrary wavefront in cylindrical coordinates.

    PubMed

    Mitri, F G

    2016-04-01

    One of the fundamental theorems in (optical, acoustical, quantum, gravitational) wave scattering is the optical theorem for plane waves, which relates the extinction cross-section to the forward scattering complex amplitude function. In this analysis, the optical theorem is extended for the case of 3D-beams of arbitrary character in a cylindrical coordinates system for any angle of incidence and any scattering angle. Generalized analytical expressions for the extinction, absorption, scattering cross-sections and efficiency factors are derived in the framework of the scalar resonance scattering theory for an object of arbitrary shape. The analysis reveals the presence of an interference scattering cross-section term, which describes interference between the diffracted or specularly reflected inelastic (Franz) waves with the resonance elastic waves. Moreover, an alternate expression for the extinction cross-section, which relates the resonance cross-section with the scattering cross-section for an impenetrable object, is obtained, suggesting an improved method for particle characterization. Cross-section expressions are also derived for known acoustical wavefronts centered on the object, defined as the on-axis case. The extended optical theorem in cylindrical coordinates can be applied to evaluate the extinction efficiency from any object of arbitrary geometry placed on or off the axis of the incident beam. Applications in acoustics, optics, and quantum mechanics should benefit from this analysis in the context of wave scattering theory and other phenomena closely connected to it, such as the multiple scattering by many particles, as well as the radiation force and torque. PMID:26836290

  5. Faraday instability on viscous ferrofluids in a horizontal magnetic field: Oblique rolls of arbitrary orientation

    NASA Astrophysics Data System (ADS)

    Mekhonoshin, V. V.; Lange, Adrian

    2002-06-01

    A linear stability analysis of the free surface of a horizontally unbounded ferrofluid layer of arbitrary depth subjected to vertical vibrations and a horizontal magnetic field is performed. A nonmonotonic dependence of the stability threshold on the magnetic field is found at high frequencies of the vibrations. The reasons for the decrease of the critical acceleration amplitude caused by a horizontal magnetic field are discussed. It is revealed that the magnetic field can be used to select the first unstable pattern of Faraday waves. In particular, a rhombic pattern as a superposition of two different oblique rolls can occur. A scaling law is presented which maps all data into one graph for the tested range of viscosities, frequencies, magnetic fields, and layer thicknesses.

  6. m-STATE INTERFERENCE WITH PARTIAL FREQUENCY REDISTRIBUTION FOR POLARIZED LINE FORMATION IN ARBITRARY MAGNETIC FIELDS

    SciTech Connect

    Sampoorna, M.

    2011-04-20

    The present paper concerns the derivation of polarized partial frequency redistribution (PRD) matrices for scattering on a two-level atom in arbitrary magnetic fields. We generalize the classical theory of PRD that is applicable to a J = 0 {yields} 1 {yields} 0 scattering transition, to other types of atomic transitions with arbitrary quantum numbers. We take into account quantum interference between magnetic substates of a given upper J-state. The generalization proceeds in a phenomenological way, based on the direct analogy between the Kramers-Heisenberg scattering amplitude in quantum mechanics and the Jones scattering matrix in classical physics. The redistribution matrices derived from such a generalization of classical PRD theory are identical to those obtained from a summed perturbative quantum electrodynamic treatment of the atom-radiation interaction. Our semi-classical approach has the advantage that it is non-perturbative, more intuitive, and lends itself more easily to further generalization (like the inclusion of J-state interference in the PRD theory).

  7. Simultaneous shaping of amplitude and phase of light in the entire output plane with a phase-only hologram.

    PubMed

    Wu, Liang; Cheng, Shubo; Tao, Shaohua

    2015-01-01

    An iterative beam shaping algorithm is proposed to simultaneously shape the amplitude and phase of an optical beam. The proposed algorithm consists of one input plane and two completely overlapped output planes which refer to the output plane in real space. The two output planes are imposed with both amplitude and phase constraints, and the constrained areas in the two output planes are complementary. As a result, both the amplitude and phase in the entire output plane are controllable and arbitrary target complex amplitudes can be achieved with the proposed algorithm. The computing result of the proposed algorithm is a phase-only distribution which can be conveniently realized with a spatial light modulator or a fabricated diffractive optical element. Both simulations and experiments have verified the high performance of the proposed algorithm.

  8. Simultaneous shaping of amplitude and phase of light in the entire output plane with a phase-only hologram

    PubMed Central

    Wu, Liang; Cheng, Shubo; Tao, Shaohua

    2015-01-01

    An iterative beam shaping algorithm is proposed to simultaneously shape the amplitude and phase of an optical beam. The proposed algorithm consists of one input plane and two completely overlapped output planes which refer to the output plane in real space. The two output planes are imposed with both amplitude and phase constraints, and the constrained areas in the two output planes are complementary. As a result, both the amplitude and phase in the entire output plane are controllable and arbitrary target complex amplitudes can be achieved with the proposed algorithm. The computing result of the proposed algorithm is a phase-only distribution which can be conveniently realized with a spatial light modulator or a fabricated diffractive optical element. Both simulations and experiments have verified the high performance of the proposed algorithm. PMID:26486183

  9. Interlimb coupling strength scales with movement amplitude.

    PubMed

    Peper, C Lieke E; de Boer, Betteco J; de Poel, Harjo J; Beek, Peter J

    2008-05-23

    The relation between movement amplitude and the strength of interlimb interactions was examined by comparing bimanual performance at different amplitude ratios (1:2, 1:1, and 2:1). For conditions with unequal amplitudes, the arm moving at the smaller amplitude was predicted to be more strongly affected by the contralateral arm than vice versa. This prediction was based on neurophysiological considerations and the HKB model of coupled oscillators. Participants performed rhythmic bimanual forearm movements at prescribed amplitude relations. After a brief mechanical perturbation of one arm, the relaxation process back to the initial coordination pattern was examined. This analysis focused on phase adaptations in the unperturbed arm, as these reflect the degree to which the movements of this arm were affected by the coupling influences stemming from the contralateral (perturbed) arm. The thus obtained index of coupling (IC) reflected the relative contribution of the unperturbed arm to the relaxation process. As predicted IC was larger when the perturbed arm moved at a larger amplitude than did the unperturbed arm, indicating that coupling strength scaled with movement amplitude. This result was discussed in relation to previous research regarding sources of asymmetry in coupling strength and the effects of amplitude disparity on interlimb coordination.

  10. New relations for gauge-theory amplitudes

    SciTech Connect

    Bern, Z.; Carrasco, J. J. M.; Johansson, H.

    2008-10-15

    We present an identity satisfied by the kinematic factors of diagrams describing the tree amplitudes of massless gauge theories. This identity is a kinematic analog of the Jacobi identity for color factors. Using this we find new relations between color-ordered partial amplitudes. We discuss applications to multiloop calculations via the unitarity method. In particular, we illustrate the relations between different contributions to a two-loop four-point QCD amplitude. We also use this identity to reorganize gravity tree amplitudes diagram by diagram, offering new insight into the structure of the Kawai-Lewellen-Tye (KLT) relations between gauge and gravity tree amplitudes. This insight leads to similar but novel relations. We expect this to be helpful in higher-loop studies of the ultraviolet properties of gravity theories.

  11. Thermal cracking and amplitude dependent attenuation

    SciTech Connect

    Johnston, D.H.; Toksoez, M.N.

    1980-02-10

    The role of crack and grain boundary contacts in determining seismic wave attenuation in rock is investigated by examining Q as a function of thermal cycling (cracking) and wave strain amplitude. Q values are obtained using a longitudinal resonant bar technique in the 10- to 20-kHz range for maximum strain amplitudes varying from roughly 10/sup -8/ to 10/sup -5/. The samples studied include the Berea and Navajo sandstones, Plexiglas, Westerly granite, Solenhofen limestone, and Frederick diabase, the latter two relatively crack free in their virgin state. Measurements were made at room temperature and pressure in air. Q values for both sandstones are constant at low strains (<10/sup -6/) but decrease rapidly with amplitude at higher strains. There is no hysteresis of Q with amplitude. Q values for Plexiglas show no indication of amplitude dependent behavior. The granite, limestone, and diabase are thermally cycled at both fast and slow heating rates in order to induce cracking. Samples slowly cycled at 400/sup 0/C show a marked increase in Q that cannot be entirely explained by outgassing of volatiles. Cycling may also widen thin cracks and grain boundaries, reducing contact areas. Samples heated beyond 400/sup 0/C, or rapidly heated, result in generally decreasing Q values. The amplitude dependence of Q is found to be coupled to the effects of thermal cycling. For rock slowly cycled 400)C or less, the transition from low-amplitude contant Q to high-amplitude variable Q behavior decreases to lower amplitudes as a function of maximum temperature. Above 400/sup 0/C, and possibly in th rapidly heated samples also, the transition moves to higher amplitudes.

  12. Amplitude modulation for the Swift-Hohenberg and Kuramoto-Sivashinski equations

    NASA Astrophysics Data System (ADS)

    Kirkinis, Eleftherios; O'Malley, Robert E.

    2014-12-01

    Employing a harmonic balance technique inspired from the methods of Renormalization Group and Multiple Scales [R. E. O'Malley, Jr. and E. Kirkinis. "A combined renormalization group-multiple scale method for singularly perturbed problems," Stud. Appl. Math. 124(4), 383-410, (2010)], we derive the amplitude equations for the Swift-Hohenberg and Kuramoto-Sivashinski equations to arbitrary order in the context of roll patterns. This new and straightforward derivation improves previous attempts and can be carried-out with symbolic computation that minimizes effort and avoids error.

  13. Independent modulations of the transmission amplitudes and phases by using Huygens metasurfaces

    NASA Astrophysics Data System (ADS)

    Wan, Xiang; Jia, Sheng Li; Cui, Tie Jun; Zhao, Yong Jiu

    2016-05-01

    We propose ultrathin Huygens metasurfaces to control transmission amplitudes and phases of electromagnetic waves independently, in which each unit cell is comprised of an electric dipole and a magnetic dipole. By altering the electric and magnetic responses of unit cells, arbitrary complex transmission coefficients with modulus values smaller than 0.85 are obtained. Two Huygens metasurfaces capable of controlling the diffraction orders are designed and fabricated by modulating the distributions of the complex transmission coefficients. More complicated functions such as holographic imaging can also be accomplished by using the proposed Huygens metasurfaces.

  14. Independent modulations of the transmission amplitudes and phases by using Huygens metasurfaces.

    PubMed

    Wan, Xiang; Jia, Sheng Li; Cui, Tie Jun; Zhao, Yong Jiu

    2016-01-01

    We propose ultrathin Huygens metasurfaces to control transmission amplitudes and phases of electromagnetic waves independently, in which each unit cell is comprised of an electric dipole and a magnetic dipole. By altering the electric and magnetic responses of unit cells, arbitrary complex transmission coefficients with modulus values smaller than 0.85 are obtained. Two Huygens metasurfaces capable of controlling the diffraction orders are designed and fabricated by modulating the distributions of the complex transmission coefficients. More complicated functions such as holographic imaging can also be accomplished by using the proposed Huygens metasurfaces. PMID:27197759

  15. Detection of Radio Signals with Unknown Duration, Amplitude, and Initial Phase

    NASA Astrophysics Data System (ADS)

    Trifonov, A. P.; Korchagin, Yu. É.; Trifonov, M. V.

    2015-10-01

    We develop the maximum-likelihood algorithm for detecting a radio signal with an arbitrary envelope shape, which is observed against the background of additive Gaussian white noise. The signal duration, amplitude, and initial phase are unknown. The developed algorithm is analyzed on the assumption of sufficiently large signal-to-noise ratios. Asymptotic expressions for the detection-error probabilities are obtained. The developed-algorithm efficiency is checked by computer simulation and the applicability range of the obtained asymptotic expressions for the algorithm characteristics is determined.

  16. Independent modulations of the transmission amplitudes and phases by using Huygens metasurfaces

    PubMed Central

    Wan, Xiang; Jia, Sheng Li; Cui, Tie Jun; Zhao, Yong Jiu

    2016-01-01

    We propose ultrathin Huygens metasurfaces to control transmission amplitudes and phases of electromagnetic waves independently, in which each unit cell is comprised of an electric dipole and a magnetic dipole. By altering the electric and magnetic responses of unit cells, arbitrary complex transmission coefficients with modulus values smaller than 0.85 are obtained. Two Huygens metasurfaces capable of controlling the diffraction orders are designed and fabricated by modulating the distributions of the complex transmission coefficients. More complicated functions such as holographic imaging can also be accomplished by using the proposed Huygens metasurfaces. PMID:27197759

  17. Resonance, particle trapping, and Landau damping in finite amplitude obliquely propagating waves

    NASA Technical Reports Server (NTRS)

    Palmadesso, P. J.

    1972-01-01

    The equations of motion for a particle in resonance with a small finite amplitude wave are solved approximately, using secularity free perturbation theory. The wave propagates at an arbitrary angle to a uniform background magnetic field in an infinite collisionless plasma. The wave fields include a longitudinal electrostatic component and elliptically polarized transverse electric and magnetic components. The trajectories of trapped and resonant untrapped particles are described, for each of the possible wave-particle resonances. These trajectories are used to construct an estimate of the nonlinear time dependent Landau damping rate of the wave.

  18. Computation of the radiation amplitude of oscillons

    NASA Astrophysics Data System (ADS)

    Fodor, Gyula; Forgács, Péter; Horváth, Zalán; Mezei, Márk

    2009-03-01

    The radiation loss of small-amplitude oscillons (very long-living, spatially localized, time-dependent solutions) in one-dimensional scalar field theories is computed in the small-amplitude expansion analytically using matched asymptotic series expansions and Borel summation. The amplitude of the radiation is beyond all orders in perturbation theory and the method used has been developed by Segur and Kruskal in Phys. Rev. Lett. 58, 747 (1987)PRLTAO0031-900710.1103/PhysRevLett.58.747. Our results are in good agreement with those of long-time numerical simulations of oscillons.

  19. Form factor and boundary contribution of amplitude

    NASA Astrophysics Data System (ADS)

    Huang, Rijun; Jin, Qingjun; Feng, Bo

    2016-06-01

    The boundary contribution of an amplitude in the BCFW recursion relation can be considered as a form factor involving boundary operator and unshifted particles. At the tree-level, we show that by suitable construction of Lagrangian, one can relate the leading order term of boundary operators to some composite operators of mathcal{N} = 4 superYang-Mills theory, then the computation of form factors is translated to the computation of amplitudes. We compute the form factors of these composite operators through the computation of corresponding double trace amplitudes.

  20. Amplitude- and rise-time-compensated filters

    DOEpatents

    Nowlin, Charles H.

    1984-01-01

    An amplitude-compensated rise-time-compensated filter for a pulse time-of-occurrence (TOOC) measurement system is disclosed. The filter converts an input pulse, having the characteristics of random amplitudes and random, non-zero rise times, to a bipolar output pulse wherein the output pulse has a zero-crossing time that is independent of the rise time and amplitude of the input pulse. The filter differentiates the input pulse, along the linear leading edge of the input pulse, and subtracts therefrom a pulse fractionally proportional to the input pulse. The filter of the present invention can use discrete circuit components and avoids the use of delay lines.

  1. A link representation for gravity amplitudes

    NASA Astrophysics Data System (ADS)

    He, Song

    2013-10-01

    We derive a link representation for all tree amplitudes in supergravity, from a recent conjecture by Cachazo and Skinner. The new formula explicitly writes amplitudes as contour integrals over constrained link variables, with an integrand naturally expressed in terms of determinants, or equivalently tree diagrams. Important symmetries of the amplitude, such as supersymmetry, parity and (partial) permutation invariance, are kept manifest in the formulation. We also comment on rewriting the formula in a GL( k)-invariant manner, which may serve as a starting point for the generalization to possible Grassmannian contour integrals.

  2. Multipole modes in deformed nuclei within the finite amplitude method

    NASA Astrophysics Data System (ADS)

    Kortelainen, M.; Hinohara, N.; Nazarewicz, W.

    2015-11-01

    Background: To access selected excited states of nuclei, within the framework of nuclear density functional theory, the quasiparticle random phase approximation (QRPA) is commonly used. Purpose: We present a computationally efficient, fully self-consistent framework to compute the QRPA transition strength function of an arbitrary multipole operator in axially deformed superfluid nuclei. Methods: The method is based on the finite amplitude method (FAM) QRPA, allowing fast iterative solution of QRPA equations. A numerical implementation of the FAM-QRPA solver module has been carried out for deformed nuclei. Results: The practical feasibility of the deformed FAM module has been demonstrated. In particular, we calculate the quadrupole and octupole strengths in a heavy deformed nucleus 240Pu, without any truncations in the quasiparticle space. To demonstrate the capability to calculate individual QRPA modes, we also compute low-lying negative-parity collective states in 154Sm. Conclusions: The new FAM implementation enables calculations of the QRPA strength function throughout the nuclear landscape. This will facilitate global surveys of multipole modes and β decays and will open new avenues for constraining the nuclear energy density functional.

  3. Amplitude modulation detection by human listeners in sound fields

    PubMed Central

    Zahorik, Pavel; Kim, Duck O.; Kuwada, Shigeyuki; Anderson, Paul W.; Brandewie, Eugene; Srinivasan, Nirmal

    2011-01-01

    The temporal modulation transfer function (TMTF) approach allows techniques from linear systems analysis to be used to predict how the auditory system will respond to arbitrary patterns of amplitude modulation (AM). Although this approach forms the basis for a standard method of predicting speech intelligibility based on estimates of the acoustical modulation transfer function (MTF) between source and receiver, human sensitivity to AM as characterized by the TMTF has not been extensively studied under realistic listening conditions, such as in reverberant sound fields. Here, TMTFs (octave bands from 2 – 512 Hz) were obtained in 3 listening conditions simulated using virtual auditory space techniques: diotic, anechoic sound field, reverberant room sound field. TMTFs were then related to acoustical MTFs estimated using two different methods in each of the listening conditions. Both diotic and anechoic data were found to be in good agreement with classic results, but AM thresholds in the reverberant room were lower than predictions based on acoustical MTFs. This result suggests that simple linear systems techniques may not be appropriate for predicting TMTFs from acoustical MTFs in reverberant sound fields, and may be suggestive of mechanisms that functionally enhance modulation during reverberant listening. PMID:22822417

  4. DESIGN OF MIRRORS AND APODIZATION FUNCTIONS IN PHASE-INDUCED AMPLITUDE APODIZATION SYSTEMS

    SciTech Connect

    Cady, Eric

    2012-08-01

    Phase-induced amplitude apodization (PIAA) coronagraphs are a promising technology for imaging exoplanets, with the potential to detect Earth-like planets around Sun-like stars. A PIAA system nominally consists of a pair of mirrors that reshape incident light without attenuation, coupled with one or more apodizers to mitigate diffraction effects or provide additional beam shaping to produce a desired output profile. We present a set of equations that allow apodizers to be chosen for any given pair of mirrors, or conversely mirror shapes chosen for given apodizers, to produce an arbitrary amplitude profile at the output of the system. We show how classical PIAA systems may be designed by this method and present the design of a novel four-mirror system with higher throughput than a standard two-mirror system. We also discuss the limitations due to diffraction and the design steps that may be taken to mitigate them.

  5. N=4 supersymmetric Yang-Mills scattering amplitudes at high energies: the Regge cut contribution

    NASA Astrophysics Data System (ADS)

    Bartels, J.; Lipatov, L. N.; Sabio Vera, A.

    2010-02-01

    We further investigate, in the planar limit of N=4 supersymmetric Yang-Mills theories, the high energy Regge behavior of six-point MHV scattering amplitudes. In particular, for the new Regge cut contribution found in our previous paper, we compute in the leading logarithmic approximation (LLA) the energy spectrum of the BFKL equation in the color octet channel, and we calculate explicitly the two-loop corrections to the discontinuities of the amplitudes for the transitions 2→4 and 3→3. We find an explicit solution of the BFKL equation for the octet channel for arbitrary momentum transfers and investigate the intercepts of the Regge singularities in this channel. As an important result we find that the universal collinear and infrared singularities of the BDS formula are not affected by this Regge-cut contribution. Any improvement of the BDS formula should reproduce this cut to all orders in the coupling.

  6. Motivic multiple zeta values and superstring amplitudes

    NASA Astrophysics Data System (ADS)

    Schlotterer, O.; Stieberger, S.

    2013-11-01

    The structure of tree-level open and closed superstring amplitudes is analyzed. For the open superstring amplitude we find a striking and elegant form, which allows one to disentangle its α‧-expansion into several contributions accounting for different classes of multiple zeta values. This form is bolstered by the decomposition of motivic multiple zeta values, i.e. the latter encapsulate the α‧-expansion of the superstring amplitude. Moreover, a morphism induced by the coproduct maps the α‧-expansion onto a non-commutative Hopf algebra. This map represents a generalization of the symbol of a transcendental function. In terms of elements of this Hopf algebra the α‧-expansion assumes a very simple and symmetric form, which carries all the relevant information. Equipped with these results we can also cast the closed superstring amplitude into a very elegant form.

  7. Nonrelativistic equations of motion for particles with arbitrary spin

    SciTech Connect

    Fushchich, V.I.; Nikitin, A.G.

    1981-09-01

    First- and second-order Galileo-invariant systems of differential equations which describe the motion of nonrelativistic particles of arbitrary spin are derived. The equations can be derived from a Lagrangian and describe the dipole, quadrupole, and spin-orbit interaction of the particles with an external field; these interactions have traditionally been regarded as purely relativistic effects. The problem of the motion of a nonrelativistic particle of arbitrary spin in a homogeneous magnetic field is solved exactly on the basis of the obtained equations. The generators of all classes of irreducible representations of the Galileo group are found.

  8. Hypersonic Arbitrary-Body Aerodynamics (HABA) for conceptual design

    SciTech Connect

    Salguero, D.E.

    1990-03-15

    The Hypersonic Arbitrary-Body Aerodynamics (HABA) computer program predicts static and dynamic aerodynamic derivatives at hypersonic speeds for any vehicle geometry. It is intended to be used during conceptual design studies where fast computational speed is required. It uses the same geometry and hypersonic aerodynamic methods as the Mark IV Supersonic/Hypersonic Arbitrary-Body Program (SHABP) developed under sponsorship of the Air Force Flight Dynamics Laboratory; however, the input and output formats have been improved to make it easier to use. This program is available as part of the Department 9140 CAE software.

  9. Arbitrary powers of D'Alembertians and the Huygens' principle

    NASA Astrophysics Data System (ADS)

    Bollini, C. G.; Giambiagi, J. J.

    1993-02-01

    By means of some reasonable rules the operators that can represent arbitrary powers of the D'Alembertian and their corresponding Green's functions are defined. It is found which powers lead to the validity of Huygens' principle. The specially interesting case of powers that are half an odd integer in spaces of odd dimensionality, obey Huygens' principle, and can be expressed as iterated D'Alembertians of the retarded potential are discussed. Arbitrary powers of the Laplacian operator as well as their corresponding Green's functions are also discussed.

  10. The amplitude of quantum field theory

    SciTech Connect

    Medvedev, B.V. ); Pavlov, V.P.; Polivanov, M.K. ); Sukhanov, A.D. )

    1989-05-01

    General properties of the transition amplitude in axiomatic quantum field theory are discussed. Bogolyubov's axiomatic method is chosen as the variant of the theory. The axioms of this method are analyzed. In particular, the significance of the off-shell extension and of the various forms of the causality condition are examined. A complete proof is given of the existence of a single analytic function whose boundary values are the amplitudes of all channels of a process with given particle number.

  11. Amplitude metrics for cellular circadian bioluminescence reporters.

    PubMed

    St John, Peter C; Taylor, Stephanie R; Abel, John H; Doyle, Francis J

    2014-12-01

    Bioluminescence rhythms from cellular reporters have become the most common method used to quantify oscillations in circadian gene expression. These experimental systems can reveal phase and amplitude change resulting from circadian disturbances, and can be used in conjunction with mathematical models to lend further insight into the mechanistic basis of clock amplitude regulation. However, bioluminescence experiments track the mean output from thousands of noisy, uncoupled oscillators, obscuring the direct effect of a given stimulus on the genetic regulatory network. In many cases, it is unclear whether changes in amplitude are due to individual changes in gene expression level or to a change in coherence of the population. Although such systems can be modeled using explicit stochastic simulations, these models are computationally cumbersome and limit analytical insight into the mechanisms of amplitude change. We therefore develop theoretical and computational tools to approximate the mean expression level in large populations of noninteracting oscillators, and further define computationally efficient amplitude response calculations to describe phase-dependent amplitude change. At the single-cell level, a mechanistic nonlinear ordinary differential equation model is used to calculate the transient response of each cell to a perturbation, whereas population-level dynamics are captured by coupling this detailed model to a phase density function. Our analysis reveals that amplitude changes mediated at either the individual-cell or the population level can be distinguished in tissue-level bioluminescence data without the need for single-cell measurements. We demonstrate the effectiveness of the method by modeling experimental bioluminescence profiles of light-sensitive fibroblasts, reconciling the conclusions of two seemingly contradictory studies. This modeling framework allows a direct comparison between in vitro bioluminescence experiments and in silico ordinary

  12. Amplitude-temporal method of speech coding

    NASA Astrophysics Data System (ADS)

    Ababii, Victor; Sudacevschi, Viorica

    2005-02-01

    A method of speech coding and decoding is proposed. The speech coding algorithm is based on first derivate calculation of input speech signal, identification of critical points and input signal amplitude in these points, time period measurement between critical points. The result of codification represents a sequence of amplitudes and time periods. The decoding algorithm utilizes values of COS or SIN functions for reconstruction on the input speech. The codec structure that consists from encoder and decoder units is proposed.

  13. Twistor-strings and gravity tree amplitudes

    NASA Astrophysics Data System (ADS)

    Adamo, Tim; Mason, Lionel

    2013-04-01

    Recently we discussed how Einstein supergravity tree amplitudes might be obtained from the original Witten and Berkovits twistor-string theory when external conformal gravitons are restricted to be Einstein gravitons. Here we obtain a more systematic understanding of the relationship between conformal and Einstein gravity amplitudes in that twistor-string theory. We show that although it does not in general yield Einstein amplitudes, we can nevertheless obtain some partial twistor-string interpretation of the remarkable formulae recently been found by Hodges and generalized to all tree amplitudes by Cachazo and Skinner. The Hodges matrix and its higher degree generalizations encode the world sheet correlators of the twistor string. These matrices control both Einstein amplitudes and those of the conformal gravity arising from the Witten and Berkovits twistor-string. Amplitudes in the latter case arise from products of the diagonal elements of the generalized Hodges matrices and reduced determinants give the former. The reduced determinants arise if the contractions in the worldsheet correlator are restricted to form connected trees at MHV. The (generalized) Hodges matrices arise as weighted Laplacian matrices for the graph of possible contractions in the correlators and the reduced determinants of these weighted Laplacian matrices give the sum of the connected tree contributions by an extension of the matrix-tree theorem.

  14. Amplitude Modulations of Acoustic Communication Signals

    NASA Astrophysics Data System (ADS)

    Turesson, Hjalmar K.

    2011-12-01

    In human speech, amplitude modulations at 3 -- 8 Hz are important for discrimination and detection. Two different neurophysiological theories have been proposed to explain this effect. The first theory proposes that, as a consequence of neocortical synaptic dynamics, signals that are amplitude modulated at 3 -- 8 Hz are propagated better than un-modulated signals, or signals modulated above 8 Hz. This suggests that neural activity elicited by vocalizations modulated at 3 -- 8 Hz is optimally transmitted, and the vocalizations better discriminated and detected. The second theory proposes that 3 -- 8 Hz amplitude modulations interact with spontaneous neocortical oscillations. Specifically, vocalizations modulated at 3 -- 8 Hz entrain local populations of neurons, which in turn, modulate the amplitude of high frequency gamma oscillations. This suggests that vocalizations modulated at 3 -- 8 Hz should induce stronger cross-frequency coupling. Similar to human speech, we found that macaque monkey vocalizations also are amplitude modulated between 3 and 8 Hz. Humans and macaque monkeys share similarities in vocal production, implying that the auditory systems subserving perception of acoustic communication signals also share similarities. Based on the similarities between human speech and macaque monkey vocalizations, we addressed how amplitude modulated vocalizations are processed in the auditory cortex of macaque monkeys, and what behavioral relevance modulations may have. Recording single neuron activity, as well as, the activity of local populations of neurons allowed us to test both of the neurophysiological theories presented above. We found that single neuron responses to vocalizations amplitude modulated at 3 -- 8 Hz resulted in better stimulus discrimination than vocalizations lacking 3 -- 8 Hz modulations, and that the effect most likely was mediated by synaptic dynamics. In contrast, we failed to find support for the oscillation-based model proposing a

  15. Kull ALE: II. Grid Motion on Unstructured Arbitrary Polyhedral Meshes

    SciTech Connect

    Anninos, P

    2002-02-11

    Several classes of mesh motion algorithms are presented for the remap phase of unstructured mesh ALE codes. The methods range from local shape optimization procedures to more complex variational minimization methods applied to arbitrary unstructured polyhedral meshes necessary for the Kull code.

  16. Arbitrary unitary transformations on optical states using a quantum memory

    SciTech Connect

    Campbell, Geoff T.; Pinel, Olivier; Hosseini, Mahdi; Buchler, Ben C.; Lam, Ping Koy

    2014-12-04

    We show that optical memories arranged along an optical path can perform arbitrary unitary transformations on frequency domain optical states. The protocol offers favourable scaling and can be used with any quantum memory that uses an off-resonant Raman transition to reversibly transfer optical information to an atomic spin coherence.

  17. Criterion for faithful teleportation with an arbitrary multiparticle channel

    NASA Astrophysics Data System (ADS)

    Cheung, Chi-Yee; Zhang, Zhan-Jun

    2009-08-01

    We present a general criterion which allows one to judge if an arbitrary multiparticle entanglement channel can be used to teleport faithfully an unknown quantum state of a given dimension. We also present a general multiparticle teleportation protocol which is applicable for all channel states satisfying this criterion.

  18. A scalable, fast, and multichannel arbitrary waveform generator

    NASA Astrophysics Data System (ADS)

    Baig, M. T.; Johanning, M.; Wiese, A.; Heidbrink, S.; Ziolkowski, M.; Wunderlich, C.

    2013-12-01

    This article reports on the development of a multichannel arbitrary waveform generator that simultaneously generates arbitrary voltage waveforms on 24 independent channels with a dynamic update rate of up to 25 Msps. A real-time execution of a single waveform and/or sequence of multiple waveforms in succession, with a user programmable arbitrary sequence order is provided under the control of a stand-alone sequencer circuit implemented using a field programmable gate array. The device is operated using an internal clock and can be synced to other devices by means of transistor-transistor logic (TTL) pulses. The device can provide up to 24 independent voltages in the range of up to ± 9 V with a dynamic update-rate of up to 25 Msps and a power consumption of less than 35 W. Every channel can be programmed for 16 independent arbitrary waveforms that can be accessed during run time with a minimum switching delay of 160 ns. The device has a low-noise of 250 μVrms and provides a stable long-term operation with a drift rate below 10 μV/min and a maximum deviation less than ± 300 μVpp over a period of 2 h.

  19. A scalable, fast, and multichannel arbitrary waveform generator.

    PubMed

    Baig, M T; Johanning, M; Wiese, A; Heidbrink, S; Ziolkowski, M; Wunderlich, C

    2013-12-01

    This article reports on the development of a multichannel arbitrary waveform generator that simultaneously generates arbitrary voltage waveforms on 24 independent channels with a dynamic update rate of up to 25 Msps. A real-time execution of a single waveform and/or sequence of multiple waveforms in succession, with a user programmable arbitrary sequence order is provided under the control of a stand-alone sequencer circuit implemented using a field programmable gate array. The device is operated using an internal clock and can be synced to other devices by means of transistor-transistor logic (TTL) pulses. The device can provide up to 24 independent voltages in the range of up to ± 9 V with a dynamic update-rate of up to 25 Msps and a power consumption of less than 35 W. Every channel can be programmed for 16 independent arbitrary waveforms that can be accessed during run time with a minimum switching delay of 160 ns. The device has a low-noise of 250 μV(rms) and provides a stable long-term operation with a drift rate below 10 μV/min and a maximum deviation less than ± 300 μV(pp) over a period of 2 h.

  20. Chaotic correlations in barrier billiards with arbitrary barriers

    NASA Astrophysics Data System (ADS)

    Osbaldestin, A. H.; Adamson, L. N. C.

    2013-06-01

    We study autocorrelation functions in symmetric barrier billiards for golden mean trajectories with arbitrary barriers. Renormalization analysis reveals the presence of a chaotic invariant set and thus that, for a typical barrier, there are chaotic correlations. The chaotic renormalization set is the analogue of the so-called orchid that arises in a generalized Harper equation.