liu.seSearch for publications in DiVA
Change search
Refine search result
12 1 - 50 of 77
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    Bingham, Robert
    et al.
    STFC Rutherford Appleton Lab, NJ USA .
    Eliasson, Bengt
    Ruhr University of Bochum, Germany .
    Mendonca, Tito
    IST Lisbon, Portugal .
    Stenflo, Lennart
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Biographical-Item: Padma Kant Shukla 1950-2013 Obituary in JOURNAL OF PLASMA PHYSICS, vol 79, issue , pp 119-1192013Other (Other academic)
    Abstract [en]

    n/a

  • 2.
    Bingham, Robert
    et al.
    Rutherford Appleton Lab, England .
    Eliasson, Bengt
    Ruhr University of Bochum, Germany .
    Tito Mendonca, Jose
    Institute Super Tecn, Portugal .
    Stenflo, Lennart
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Ion acceleration by Alfven waves on auroral field lines2013In: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. 87, no 5Article in journal (Refereed)
    Abstract [en]

    Observations of ion acceleration along auroral field lines at the boundary of the plasma sheet and tail lobe of the Earth show that the energy of the ions increases with decreasing density. The observations can be explained by ion acceleration through Landau resonance with kinetic Alfven waves (KAWs) such that k(A) . v(i) = omega(A), where k(A) is the wave vector, v(i) is the ion resonance velocity and omega(A) is the Alfven wave frequency. The ion resonance velocities are proportional to the Alfven velocity which increases with decreasing density. This is in agreement with the data if the process is occurring at the plasma sheet tail lobe boundary. A quasi-linear theory of ion acceleration by KAWs is presented. These ions propagate both down towards and away from the Earth. The paths of the Freja and Polar satellites indicate that the acceleration takes place between the two satellites, between 1Re and 5Re. The downward propagating ions develop a horseshoe-type of distribution which has a positive slope in the perpendicular direction. This type of distribution can produce intense lower hybrid wave activity, which is also observed. Finally, the filamentation of shear Alfven waves is considered. It may be responsible for large-scale density striations.

  • 3.
    Brodin, G
    et al.
    Umeå University, Sweden .
    Stenflo, Lennart
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Alfven wave interactions within the Hall-MHD description2013In: Journal of Plasma Physics, ISSN 0022-3778, E-ISSN 1469-7807, Vol. 79, p. 909-911Article in journal (Refereed)
    Abstract [en]

    We show that comparatively simple expressions for the Alfven wave coupling coefficients can be deduced from the well-known Hall-magnetohydrodynamics (MHD) model equations.

  • 4.
    Brodin, G.
    et al.
    Umeå University, Sweden .
    Stenflo, Lennart
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Large amplitude electron plasma oscillations2014In: Physics Letters A, ISSN 0375-9601, E-ISSN 1873-2429, Vol. 378, no 22-23, p. 1632-1635Article in journal (Refereed)
    Abstract [en]

    We consider a cold plasma in order to find new large-amplitude wave solutions in the long-wavelength limit. Accordingly we derive two generic coupled equations which describe the energy exchange between the electrostatic and electromagnetic waves. A new kind of quasi-periodic behavior is found. Our derivations may be considered as a prerequisite to extended studies of stimulated Raman scattering for cases where the wave amplitudes are so large that standard perturbation techniques are not applicable.

  • 5.
    Brodin, G.
    et al.
    Umea Univ, Dept Phys, SE-90187 Umea, Sweden.
    Stenflo, Lennart
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Nonlinear dynamics of large amplitude modes in a magnetized plasma2014In: Physics of Plasmas, ISSN 1070-664X, E-ISSN 1089-7674, Vol. 21, p. 122301-Article in journal (Refereed)
    Abstract [en]

    We derive two equations describing the coupling between electromagnetic and electrostaticoscillations in one-dimensional geometry in a magnetized cold and non-relativistic plasma. The nonlinear interaction between the wave modes is studied numerically. The effects of the external magnetic field strength and the initial electromagneticpolarization are of particular interest here. New results can, thus, be identified.

  • 6.
    Brodin, G.
    et al.
    Umeå University, Sweden.
    Stenflo, Lennart
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Nonlinear wave interactions of kinetic sound waves2015In: Annales Geophysicae, ISSN 0992-7689, E-ISSN 1432-0576, Vol. 33, no 8, p. 1007-1010Article in journal (Refereed)
    Abstract [en]

    We reconsider the nonlinear resonant interaction between three electrostatic waves in a magnetized plasma. The general coupling coefficients derived from kinetic theory are reduced here to the low-frequency limit. The main contribution to the coupling coefficient we find in this way agrees with the coefficient recently presented in Annales Geophysicae. But we also deduce another contribution which sometimes can be important, and which qualitatively agrees with that of an even more recent paper. We have thus demonstrated how results derived from fluid theory can be improved and generalized by means of kinetic theory. Possible extensions of our results are outlined.

  • 7.
    Brodin, G
    et al.
    Department of Physics, Umeå University, Umeå, Sweden.
    Stenflo, Lennart
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology. Department of Physics, Umeå University, Umeå, Sweden.
    On the parametric decay of waves in magnetized plasmas2009In: Journal of Plasma Physics, ISSN 0022-3778, E-ISSN 1469-7807, Vol. 75, p. 9-13Article in journal (Other academic)
    Abstract [en]

    We reconsider the theory for three-wave interactions in cold plasmas. In particular, we demonstrate that previously overlooked formulations of the general theory are highly useful when deriving concrete expressions for specific cases. We also pointout that many previous results deduced directly from the basic plasma equations contain inappropriate approximations leading to unphysical results. Finally, generalizations to more elaborate plasma models containing, for example, kinetic effects are given.

  • 8.
    Brodin, G
    et al.
    Umeå University.
    Stenflo, Lennart
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Three-wave coupling coefficients for a magnetized plasma2012In: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. 85, no 3, p. 035504-Article in journal (Refereed)
    Abstract [en]

    The resonant interaction between three waves in a uniform magnetized plasma is reconsidered. Starting from previous kinetic expressions, which contain a general but too little used result, we are able to improve the formulae. This leads to an explicit expression for the three-wave coupling coefficient which applies for arbitrary wave propagation in a magnetized Vlasov plasma.

  • 9.
    Brodin, G.
    et al.
    Umeå University, Sweden.
    Stenflo, Lennart
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Three-wave coupling coefficients for perpendicular wave propagation in a magnetized plasma2015In: Physics of Plasmas, ISSN 1070-664X, E-ISSN 1089-7674, Vol. 22, no 10, article id 104503Article in journal (Refereed)
    Abstract [en]

    The resonant interaction between three waves in a uniform magnetized plasma is reconsidered. Starting from previous kinetic expressions, we limit our investigation to waves propagating perpendicularly to the external magnetic field. It is shown that reliable results can only be obtained in the two-dimensional case, i.e., when the wave vectors have both x and y components. (C) 2015 AIP Publishing LLC.

  • 10.
    Brodin, G.
    et al.
    Umeå University, Sweden .
    Stenflo, Lennart
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Wave Generation in a Warm Magnetized Multi-Component Plasma2014In: Contributions to Plasma Physics, ISSN 0863-1042, E-ISSN 1521-3986, Vol. 54, no 7, p. 623-625Article in journal (Refereed)
    Abstract [en]

    The resonant interaction between three waves propagating perpendicularly to an external magnetic field in a plasma is considered. We present the explicit expressions for the three wave coupling coefficients of a warm multi-component plasma. The results of previous work on the generation of THz radiation by laser plasma interaction are significantly improved.

  • 11.
    Brodin, Gert
    et al.
    Umeå University, Umeå, Sweden.
    Stenflo, Lennart
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Stimulated Brillouin scattering in magnetized plasmas2013In: Journal of Plasma Physics, ISSN 0022-3778, E-ISSN 1469-7807, Vol. 79, no 6, p. 983-986Article in journal (Refereed)
    Abstract [en]

    Previous theory for stimulated Brillouin scattering is reconsidered and generalized. We introduce an effective ion sound velocity that turns out to be useful in describing scattering instabilities.

  • 12.
    Brodin, Gert
    et al.
    Umeå University, Sweden.
    Stenflo, Lennart
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Three-wave coupling coefficients for a magnetized plasma2012Conference paper (Other academic)
    Abstract [en]

    The resonant interaction between three waves in a uniform magnetized plasma is reconsidered. Starting from previous kinetic expressions, that contain a general but too little used result, we are able to improve the formulas. This leads to an explicit expression for the three wave coupling coefficient which applies for arbitrary wave propagation in a magnetized Vlasov plasma.

  • 13.
    Daldorff, L. K. S.
    et al.
    University of Michigan.
    Pecseli, H. L.
    University of Oslo.
    Trulsen, J. K.
    University of Oslo.
    Ulriksen, M. I.
    Norwegian Water Resources and Energy Directorate.
    Eliasson, B.
    Ruhr University Bochum.
    Stenflo, Lennart
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics . Linköping University, The Institute of Technology.
    Nonlinear beam generated plasma waves as a source for enhanced plasma and ion acoustic lines2011In: Physics of Plasmas, ISSN 1070-664X, E-ISSN 1089-7674, Vol. 18, no 5, p. 052107-Article in journal (Refereed)
    Abstract [en]

    Observations by, for instance, the EISCAT Svalbard Radar (ESR) demonstrate that the symmetry of the naturally occurring ion line in the polar ionosphere can be broken by an enhanced, nonthermal, level of fluctuations (naturally enhanced ion-acoustic lines, NEIALs). It was in many cases found that the entire ion spectrum can be distorted, also with the appearance of a third line, corresponding to a propagation velocity significantly slower than the ion acoustic sound speed. It has been argued that selective decay of beam excited primary Langmuir waves can explain some phenomena similar to those observed. We consider a related model, suggesting that a primary nonlinear process can be an oscillating two-stream instability, generating a forced low frequency mode that does not obey any ion sound dispersion relation. At later times, the decay of Langmuir waves can give rise also to enhanced asymmetric ion lines. The analysis is based on numerical results, where the initial Langmuir waves are excited by a cold dilute electron beam. By this numerical approach, we can detect fine details of the physical processes, in particular, demonstrate a strong space-time intermittency of the electron waves in agreement with observations. Our code solves the full Vlasov equation for electrons and ions, with the dynamics coupled through the electrostatic field derived from Poissons equation. The analysis distinguishes the dynamics of the background and beam electrons. This distinction simplifies the analysis for the formulation of the weakly nonlinear analytical model for the oscillating two-stream instability. The results have general applications beyond their relevance for the ionospheric observations.

  • 14.
    Dieckmann, Mark E
    et al.
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Shukla, P K
    Ruhr University Bochum.
    Stenflo, Lennart
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics . Linköping University, The Institute of Technology.
    Simulation study of the filamentation of counter-streaming beams of the electrons and positrons in plasmas2009In: PLASMA PHYSICS AND CONTROLLED FUSION, ISSN 0741-3335, Vol. 51, no 6, p. 065015-Article in journal (Refereed)
    Abstract [en]

    The filamentation instability (FI) driven by two spatially uniform and counter-streaming beams of charged particles in plasmas is modelled by a particle-in-cell simulation. Each beam consists of electrons and positrons. The four species are equally dense and have the same temperature. The one-dimensional simulation direction is orthogonal to the beam velocity vector. The magnetic field grows spontaneously and rearranges the particles in space, such that the distributions of the electrons of one beam and the positrons of the second beam match. The simulation demonstrates that as a result no electrostatic field is generated by the magnetic field through its magnetic pressure gradient prior to its saturation. This electrostatic field would be repulsive at the centres of the filaments and limit the maximum charge and current density. The filaments of electrons and positrons in this simulation reach higher charge and current densities than in one with no positrons. The oscillations of the magnetic field strength induced by the magnetically trapped particles result in an oscillatory magnetic pressure gradient force. The latter interplays with the statistical fluctuations in the particle density and it probably enforces a charge separation, by which electrostatic waves grow after the FI has saturated.

  • 15.
    Eliasson, B.
    et al.
    Department of Physics Umeå University.
    Stenflo, Lennart
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics . Linköping University, The Institute of Technology.
    Full-scale simulation study of the initial stage of ionospheric turbulence2008In: Journal of Geophysical Research, ISSN 0148-0227, E-ISSN 2156-2202, Vol. 113, no 0148-0227, p. A02305-1-A02305-9Article in journal (Refereed)
    Abstract [en]

    We present a full-scale simulation of the nonlinear interaction between an intense electromagnetic wave and the Earth's ionosphere, by means of a generalized Zakharov model. The radio wave propagates from the neutral atmosphere into the ionospheric plasma layer and reaches the turning points of the ordinary and extraordinary wave modes. At the turning point of the ordinary mode, a parametric instability takes place in which the electromagnetic wave decays into an electron plasma wave and an ion acoustic wave with a typical wavelength of one meter. This is followed by collapse and caviton formation and trapping of the intense electron plasma wave. The cavitons lead to an efficient excitation of slow X (or Z) waves that propagate further into the denser ionospheric layer at higher altitudes. We use a realistic ion (oxygen) mass, length scales, and other plasma parameters. This numerical study should be useful for understanding the nonlinear interaction between intense radio waves and the ionosphere.   

  • 16.
    Eliasson, B.
    et al.
    University of Strathclyde, Scotland .
    Stenflo, Lennart
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Bingham, R.
    Rutherford Appleton Lab, England .
    Mendonca, J. T.
    Institute Super Tecn, Portugal .
    Biographical-Item: Preface in JOURNAL OF PLASMA PHYSICS, vol 79, issue , pp 981-9812013Other (Other academic)
    Abstract [en]

    n/a

  • 17.
    Eliasson, B
    et al.
    University of Strathclyde, Glasgow, UK.
    Stenflo, Lennart
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Bingham, R
    Rutherford Appleton Laboratory, Didcot, UK.
    Mendonca, J T
    Institute Superior Tecnico, Lisboa, Portugal.
    Preface to special issue2013In: Journal of Plasma Physics, ISSN 0022-3778, E-ISSN 1469-7807, Vol. 79, no 6, p. 981-981Article in journal (Other academic)
    Abstract [en]

    This special issue is devoted to the memory of Professor Padma Kant Shukla, who passed away 26 January 2013 on his travel to New Delhi, India to receive the prestigious Hind Rattan (Jewel of India) award. Padma was born in Tulapur, Uttar Pradesh, India, 7 July 1950, where he grew up and got his education. He received a PhD degree in Physics at the Banaras Hindu University, Varanasi, Uttar Pradesh, India, in 1972, under the supervision of late Prof. R. N. Singh, and a second PhD degree in Theoretical Plasma Physics from Umeå University in Sweden in 1975, under the supervision of Prof. Lennart Stenflo. He worked at the Faculty of Physics & Astronomy, Ruhr-University Bochum, Germany since January 1973, where he was a permanent faculty member and Professor of International Affairs, a position that was created for him to honour his international accomplishments and reputation.

  • 18.
    Eliasson, Bengt
    et al.
    Ruhr University Bochum.
    Stenflo, Lennart
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics . Linköping University, The Institute of Technology.
    Full-scale simulation study of stimulated electromagnetic emissions: The first ten milliseconds2010In: JOURNAL OF PLASMA PHYSICS, ISSN 0022-3778, Vol. 76, p. 369-375Article in journal (Refereed)
    Abstract [en]

    A full-scale numerical study is performed of the nonlinear interaction between a large-amplitude electromagnetic wave and the Earths ionosphere; and of the stimulated electromagnetic emission emerging from the turbulent layer, during the first 10 milliseconds after switch-on of the radio transmitter. The frequency spectra are downshifted in frequency and appear to emerge from a region somewhat below the cutoff of the O mode, which is characterized by Langmuir wave turbulence and localized Langmuir envelopes trapped in ion density cavities. The spectral features of escaping O-mode waves are very similar to those observed in experiments. The frequency components of Z-mode waves, trapped in the region between the O- and Z-mode cutoffs show strongly asymmetric and downshifted spectra.

  • 19.
    Gradov, O.M.
    et al.
    N.S. Kurnakov Institute of the Russian Academy of Sciences.
    Stenflo, Lennart
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics . Linköping University, The Institute of Technology.
    Shukla, P.K.
    Department of Physics Umea University.
    Non-linear effects in a cold electron plasma with non-uniform density profile2008In: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. 77, p. 055503-1-055503-3Article in journal (Refereed)
    Abstract [en]

     A new step forward on the theory for two-dimensional wave propagation is outlined for a non-uniform plasma with a smooth density profile. A way to excite envelope solitary waves with certain shapes is described. The corresponding wave space structure is calculated, and the restrictions on the wave profile along the direction of wave propagation are noticed.

  • 20.
    Kaladze, T. D.
    et al.
    I. Vekua institute of Applied Mathematics Tbilisi State University.
    Pochotelov, O.A.
    Institute of Physics of the Earth.
    Stenflo, Lennart
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics . Linköping University, The Institute of Technology.
    Rogava, J.
    I. Vekua institute of Applied Mathematics Tbilisi State University.
    Tsamalashvili, L.V.
    I. Vekua institute of Applied Mathematics Tbilisi State University.
    Tsiklauri, M.
    I. Vekua institute of Applied Mathematics Tbilisi State University.
    Zonal flow interaction with Rossby waves in the Earth's atmosphere: A numerical simulation2008In: Physics Letters A, ISSN 0375-9601, E-ISSN 1873-2429, Vol. 372, no 31, p. 5177-5180Article in journal (Refereed)
    Abstract [en]

    A numerical simulation of the Charney-Obukhov equation modified by the presence of a sheared zonal flow is carried out. The zonal flow is assumed to propagate longitudinally and is sheared along the meridians. It is shown that owing to the nonlinear interaction of the sheared zonal flow with the initially given disturbances the energy of the zonal flow is accumulating into the formations which are broken into several pieces. As a result new solitary vortex structures arise to produce the structural turbulence

  • 21.
    Kaladze, T D
    et al.
    Tbilisi State University.
    Pokhotelov, O A
    Moscow.
    Shah, H A
    GC University.
    Khan, M I
    GC University.
    Stenflo, Lennart
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics . Linköping University, The Institute of Technology.
    Acoustic-gravity waves in the Earths ionosphere2008In: Journal of Atmospheric and Solar-Terrestrial Physics, ISSN 1364-6826, E-ISSN 1879-1824, Vol. 70, no 13, p. 1607-1616Article in journal (Refereed)
    Abstract [en]

    Taking into account the existence of charged particles in the Earths ionosphere the propagation of acoustic-gravity waves is investigated. The influence of the Coriolis force is also taken into account. The weakly ionized ionospheric D, E, and F-layers are considered. The existence of a cut-off frequency at 2 Omega(0) (Omega(0) is the value of the angular velocity of the Earths rotation) is noted. It is shown that the linear waves are damped because of the Pedersen conductivity. When the acoustic-gravity waves are excited by external events (volcanic eruptions, earthquakes, lightning strikes, etc.) their amplitudes grow until self-organization of these waves into nonlinear vortex solitary structures is admitted. Taking into account the interaction of the induced ionospheric current with the geomagnetic field the governing nonlinear equations are deduced. The formation of dipole vortex solitary structures of low-frequency internal gravity waves is shown for the stable stratified ionosphere. The dynamic energy equation for such nonlinear structures is obtained. It is shown that nonlinear solitary vortical structures damp due to joule losses.

  • 22.
    Karimov, A R
    et al.
    Russian Academy of Science.
    Stenflo, Lennart
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics . Linköping University, The Institute of Technology.
    Yu, M Y
    Zhejiang University.
    Coupled azimuthal and radial flows and oscillations in a rotating plasma2009In: PHYSICS OF PLASMAS, ISSN 1070-664X, Vol. 16, no 6, p. 062313-Article in journal (Refereed)
    Abstract [en]

    Nonlinear coupling between the radial, axial, and azimuthal flows in a cold rotating plasma is considered nonperturbatively by first constructing a basis solution for a rotating flow. Simple but exact solutions that describe an expanding plasma with oscillatory flow fields are then obtained. These solutions show that the energy in the radial and axial flow components can be transferred to the azimuthal component but not the vice versa. Nonlinear electron velocity oscillations in the absence of electron density oscillations at the same frequency are shown to exist.

  • 23.
    Karimov, A R
    et al.
    Russian Acadamy Science.
    Stenflo, Lennart
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics . Linköping University, The Institute of Technology.
    Yu, M Y
    Zhejiang University.
    Coupled flows and oscillations in asymmetric rotating plasmas2009In: PHYSICS OF PLASMAS, ISSN 1070-664X, Vol. 16, no 10, p. 102303-Article in journal (Refereed)
    Abstract [en]

    Nonlinear coupling among the radial, axial, and azimuthal flows in an asymmetric cold rotating plasma is considered nonperturbatively. Exact solutions describing an expanding or contracting plasma with oscillations are then obtained. It is shown that despite the flow asymmetry the energy in the radial and axial flow components can be transferred to the azimuthal component but not the vice versa, and that flow oscillations need not be accompanied by density oscillations. (C) 2009 American Institute of Physics. [doi: 10.1063/1.3247875]

  • 24.
    Karimov, A R
    et al.
    Russian Academy of Sciences, Moscow, Russia.
    Yu, M Y
    Zhejiang University, Hangzhou, China .
    Stenflo, Lennart
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Asymmetric oscillatory expansion of a cylindrical plasma2013In: Journal of Plasma Physics, ISSN 0022-3778, E-ISSN 1469-7807, Vol. 79, no 6, p. 1007-1009Article in journal (Refereed)
    Abstract [en]

    Asymmetric oscillatory expansion of a cylindrical plasma layer into vacuum is investigated analytically by solving the fluid equations of the electrons and ions together with the Maxwell's equations. For the problem considered, it is found that the asymmetrical flow components are strongly affected by the symmetrical components, but not the vice versa.

  • 25.
    Karimov, A. R.
    et al.
    Institute for High Temperatures, Russian Academy of Science, Moscow.
    Yu, M. Y.
    Zhejiang University, Hangzhou.
    Stenflo, Lennart
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology. Umea Univ, Dept Plasma Phys, SE-90187 Umea, Sweden.
    Expansion of a cold non-neutral plasma slab2014In: Physics of Plasmas, ISSN 1070-664X, E-ISSN 1089-7674, Vol. 21, p. 122304-Article in journal (Refereed)
    Abstract [en]

    Expansion of the ion and electron fronts of a cold non-neutral plasma slab with a quasi-neutral core bounded by layers containing only ions is investigated analytically and exact solutions are obtained. It is found that on average, the plasma expansion time scales linearly with the initial inverse ion plasma frequency as well as the degree of charge imbalance, and no expansion occurs if the cold plasma slab is stationary and overall neutral. However, in both cases, there can exist prominent oscillations on the electron front.

  • 26.
    Karimov, A R
    et al.
    Russian Academy of Science, Russia .
    Yu, M Y
    Zhejiang University, Peoples R China Ruhr University of Bochum, Germany .
    Stenflo, Lennart
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Large quasineutral electron velocity oscillations in radial expansion of an ionizing plasma2012In: Physics of Plasmas, ISSN 1070-664X, E-ISSN 1089-7674, Vol. 19, no 9, p. 092118-Article in journal (Refereed)
    Abstract [en]

    Radial expansion of an ionizing gas or plasma cylinder into vacuum is investigated. An exact model for the evolution of the density and velocity fields of the electrons, ions, and neutrals, including the effect of photo and electron-impact ionization on the flow characteristics is developed and solutions obtained. A quasineutral nonlinear electrostatic mode involving rapid oscillations in the electron velocity but not in the density can occur in the expanding plasma. The mode turns out to be almost unaffected by weak ionization.

  • 27.
    Karimov, A.R.
    et al.
    Russian Academy of Science.
    Yu, M.Y.
    Zhejiang University.
    Stenflo, Lennart
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics . Linköping University, The Institute of Technology.
    Flow oscillations in radial expansion of an inhomogeneous plasma layer2011In: Physics Letters A, ISSN 0375-9601, E-ISSN 1873-2429, Vol. 375, no 27, p. 2629-2636Article in journal (Refereed)
    Abstract [en]

    The cylindrically cylindrically symmetric radial evolution of an inhomogeneous plasma layer expanding into vacuum is investigated nonperturbatively by first determining the spatial structure of the plasma flow structure. The evolution is then governed by a set of ordinary differential equations. The effect of the plasma inhomogeneity on the nonlinear coupling among the electron and ion flow components and oscillations is investigated.

  • 28.
    Lu, Gaimin
    et al.
    Dalian University Technology.
    Liu, Yue
    Dalian University Technology.
    Wang, Youmei
    Zhejiang University.
    Stenflo, Lennart
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics . Linköping University, The Institute of Technology.
    Popel, S I
    Russian Academy of Science.
    Yu, M Y
    Zhejiang University.
    Fully nonlinear electrostatic waves in electron-positron plasmas2010In: JOURNAL OF PLASMA PHYSICS, ISSN 0022-3778, Vol. 76, p. 267-275Article in journal (Refereed)
    Abstract [en]

    Fully nonlinear electrostatic waves in a plasma containing electrons, positrons, and ions are investigated by solving the governing equations exactly. It is found that both smooth and spiky quasistationary waves exist, and large-amplitude waves necessarily have large-phase velocities, but small-amplitude waves can be both fast and slow.

  • 29.
    Marklund, M
    et al.
    Umeå University.
    Brodin, G
    Umeå University.
    Stenflo, Lennart
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics . Linköping University, The Institute of Technology.
    Liu, C S
    University of Maryland.
    New quantum limits in plasmonic devices2008In: EPL : a letters journal exploring the frontiers of physics, ISSN 0295-5075, Vol. 84, no 1, p. 17006-Article in journal (Refereed)
    Abstract [en]

    Surface plasmon polaritons (SPPs) have recently been recognized as an important future technique for microelectronics. Such SPPs have been studied using classical theory. However, current state-of-the-art experiments are rapidly approaching nanoscales, and quantum effects can then become important. Here we study the properties of quantum SPPs at the interface between an electron quantum plasma and a dielectric material. It is shown that the effect of quantum broadening of the transition layer is most important. In particular, the damping of SPPs does not vanish even in the absence of collisional dissipation, thus posing a fundamental size limit for plasmonic devices. Consequences and applications of our results are pointed out.

  • 30.
    Marklund, Mattias
    et al.
    Physics Department Umea University.
    Eliasson, Bengt
    Institute of Theoretical Physics IV Ruhr-University Bochum, Germany.
    Shukla, Padma K
    Institute of Theoretical Physics IV Ruhr-University Bochum, Germany.
    Stenflo, Lennart
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics . Linköping University, The Institute of Technology.
    Dieckmann, Mark E
    Ruhr-Universität Bochum.
    Parviainen, Madelene
    Institute of Theoretical Physics IV Ruhr-University Bochum, Germany.
    Electrostatic pair creation and recombination in quantum plasmas2006In: JETP Letters: Journal of Experimental And Theoretical Physics Letters, ISSN 0021-3640, E-ISSN 1090-6487, Vol. 83, no 8, p. 313-317Article in journal (Refereed)
    Abstract [en]

    The production of electron-positron pairs by electrostatic waves in quantum plasmas is investigated. In particular, a semiclassical governing set of equations for a self-consistent treatment of pair creation by the Schwinger mechanism in a quantum plasma is derived.

  • 31.
    Marklund, Mattias
    et al.
    Umeå University.
    Stenflo, Lennart
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics . Linköping University, The Institute of Technology.
    Viewpoint: Exciting roque waves: in Physics, vol 2, number 862009Other (Other (popular science, discussion, etc.))
    Abstract [en]

    n/a

  • 32.
    Mendonca, J. T.
    et al.
    Instituto Superior Técnico, Lisboa.
    Onishchenko, O G
    Institute of Physics of the Earth, Moscow, Russia.
    Pokhotelov, O A
    Institute of Physics of the Earth, Moscow, Russia.
    Stenflo, Lennart
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Wave-kinetic description of atmospheric turbulence2014In: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. 89, p. 125004-Article in journal (Refereed)
    Abstract [en]

    We propose a wave-kinetic description of atmospheric turbulence, where the turbulence spectrum is described as a gas of quasi-particles. We apply this description to the case of zonal structures in the atmosphere, which can be excited by internal gravity wave turbulence. A general expression for the instability growth rates is derived, and the particular example of a nearly mono-kinetic turbulent spectrum is discussed.

  • 33.
    Mendonca, J. T.
    et al.
    Institute Super Tecn, Portugal.
    Stenflo, Lennart
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Acoustic-gravity waves in the atmosphere: from Zakharov equations to wave-kinetics2015In: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. 90, no 5, p. 055001-Article in journal (Refereed)
    Abstract [en]

    We develop a wave-kinetic description of acoustic-gravity (AG) waves in the atmosphere. In our paper the high frequency spectrum of waves is described as a gas of quasi-particles. Starting from the Zakharov-type of equations, where coupling between fast and slow density perturbations is considered, we derive the corresponding wave-kinetic equations, written in terms of an appropriate Wigner function. This provides an alternative description for the nonlinear interaction between the two dispersion branches of the AG waves.

  • 34.
    Onishchenko, O. G.
    et al.
    Institute Phys Earth, Russia; Moscow Space Research Institute, Russia.
    Horton, W.
    Institute Mediterranean AMU, France; University of Texas Austin, TX 78712 USA; Aix Marseilles University, France.
    Pokhotelov, O. A.
    Institute Phys Earth, Russia.
    Stenflo, Lennart
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Dust devil generation2014In: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. 89, no 7, p. 075606-Article in journal (Refereed)
    Abstract [en]

    The equations describing axi-symmetric nonlinear internal gravity waves in an unstable atmosphere are derived. A hydrodynamic model of a dust devil generation mechanism in such an atmosphere is investigated. It is shown that in an unstably stratified atmosphere the convective plumes with poloidal motion can grow exponentially. Furthermore, it is demonstrated that these convective plumes in an atmosphere with weak large scale toroidal motion are unstable with respect to three-dimensional dust devil generation.

  • 35.
    Onishchenko, O G
    et al.
    Institute Phys Earth, Moscow.
    Pokhotelov, O A
    Institute Phys Earth, Moscow.
    Stenflo, Lennart
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Shukla, P K
    University of Bochum.
    Stabilization of magnetic curvature-driven Rayleigh-Taylor instabilities2012In: Journal of Plasma Physics, ISSN 0022-3778, E-ISSN 1469-7807, Vol. 78, p. 93-97Article in journal (Refereed)
    Abstract [en]

    The finite ion Larmor radius (FLR) stabilization of the magnetic curvature-driven Rayleigh Taylor (MCD RT) instability in a low beta plasma with nonzero ion temperature gradient is investigated. Finite electron temperature effects and ion temperature perturbations are incorporated. A new set of nonlinear equations for flute waves with arbitrary wavelengths as compared with the ion Larmor radius in a plasma with curved magnetic field lines is derived. Particular attention is paid to the waves with spatial scales of the order of the ion Larmor radius. In the linear limit, a Fourier transform of these equations yields an improved dispersion relation for flute waves. The dependence of the M CD RT instability growth rate on the equilibrium plasma parameters and the wavelengths is studied. The condition for which the instability cannot be stabilized by the FLR effects is found.

  • 36.
    Onishchenko, O G
    et al.
    Institute Phys Earth, Moscow.
    Pokhotelov, O A
    Institute Phys Earth, Moscow.
    Stenflo, Lennart
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics . Linköping University, The Institute of Technology.
    Shukla, P K
    Ruhr University Bochum.
    The magnetic Rayleigh-Taylor instability and flute waves at the ion Larmor radius scales2011In: PHYSICS OF PLASMAS, ISSN 1070-664X, Vol. 18, no 2, p. 022106-Article in journal (Refereed)
    Abstract [en]

    The theory of flute waves (with arbitrary spatial scales compared to the ion Larmor radius) driven by the Rayleigh-Taylor instability (RTI) is developed. Both the kinetic and hydrodynamic models are considered. In this way we have extended the previous analysis of RTI carried out in the long wavelength limit. It is found that complete finite ion Larmor radius stabilization is absent when the ion diamagnetic velocity attains the ion gravitation drift velocity. The hydrodynamic approach allowed us to deduce a new set of nonlinear equations for flute waves with arbitrary spatial scales. It is shown that the previously deduced equations are inadequate when the wavelength becomes of the order of the ion Larmor radius. In the linear limit a Fourier transform of these equations yields the dispersion relation which in the so-called Pade approximation corresponds to the results of the fully kinetic treatment. The development of such a theory gives us enough grounds for an adequate description of the RTI stabilization by the finite ion Larmor radius effect.

  • 37.
    Onishchenko, O. G.
    et al.
    Institute of Physics of the Earth, Moscow, Russian Federation.
    Pokhotelov, O. A.
    Institute of Physics of the Earth, Moscow, Russian Federation.
    Stenflo, Lennart
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Shukla, Padma K.
    Ruhr University Bochum, Germany .
    Finite ion Larmor radius effects in magnetic curvature-driven Rayleigh-Taylor instability2011In: AIP Conference Proceeding Joint ITER-IAEA-ICTP Advanced Workshop on Fusion and Plasma Physics / [ed] Padma K. Shukla and Bengt Eliasson, American Institute of Physics (AIP), 2011, Vol. 1445, p. 68-73Conference paper (Other academic)
    Abstract [en]

    Incomplete finite ion Larmor radius stabilization of the magnetic Rayleigh-Taylor (RT)instability is investigated. In contrast to the previous studies the effects of both the gravity and magnetic field curvature are taken into account. New model hydrodynamic equations describing nonlinear flute waves with arbitrary spatial scales have been derived. Particular attention is paid to the waves with spatial scales of the order of the ion Larmor radius. In the linear approximation a Fourier transform of these equations yields a generalized dispersion relation for flute waves. The condition for gravity and magnetic curvature at which the instability cannot be stabilized by the finite ion Larmor radius effects is found. It is shown that in the absence of the magnetic curvature the complete stabilization arises due to the cancellation of gravitational and diamagnetic drifts. However, when the magnetic curvature drift is taken into account this synchronization is violated and the RT instability is stabilized at more complex conditions. Furthermore, the dependence of the instability growth rate on the equilibrium plasma parameters is investigated.

  • 38.
    Pokhotelov, O.A.
    et al.
    Institute Phys Earth, Russia .
    Onishchenko, O.G.
    Institute Phys Earth, Russia .
    Stenflo, Lennart
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Physical mechanisms for electron mirror and field swelling modes2013In: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. 87, no 6, p. 065303-Article in journal (Refereed)
    Abstract [en]

    Ion mirror instability is dominant in planetary and cometary magnetosheaths and other high-beta plasmas where the ions are hotter than the electrons. It is associated with a zero-frequency non-propagating mode with the wave vector nearly perpendicular to the ambient magnetic field. The counterparts of this instability in hot electron plasmas are the field swelling and electron mirror instabilities. A theory for these instabilities was developed more than two decades ago (Basu B and Coppi B 1982 Phys. Rev. Lett. 48 799, 1984 Phys. Fluids 27 1187) within the framework of a fluid model. The connection between the two types of instabilities has been analyzed in (Migliuolo S 1986 J. Geophys. Res. 91 7981). In contrast to these papers, we shall here adopt the standard quasi-hydrodynamic approach that is usually used for the study of mirror instabilities. To analyze the electron mirror and field swelling instabilities, we will only use the perpendicular balance condition and the Liouville theorem. We have found that such a description is easier to understand and gives us increased physical insight into the basic physical features of both these instabilities.

  • 39.
    Shukla, N.
    et al.
    Umeå University, Sweden.
    Brodin, G.
    Umeå University, Sweden.
    Marklund, M.
    Umeå University, Sweden.
    Shukla, P.K.
    Umeå University, Sweden.
    Stenflo, Lennart
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Erratum: Nonlinear electromagnetic wave equations for superdense magnetized plasmas (Physics of Plasmas (2009) 16 (072114)): in Physics of Plasmas, vol 16, issue 8, publication number 0899042009In: Physics of Plasmas, ISSN 1070-664X, E-ISSN 1089-7674, Vol. 16, no 8, p. 089904-Article in journal (Other academic)
    Abstract [en]

    [No abstract available]

  • 40.
    Shukla, Nitin
    et al.
    Umeå University.
    Brodin, G
    Umeå University.
    Marklund, M
    Umeå University.
    Shukla, P K
    Umeå University.
    Stenflo, Lennart
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics . Linköping University, The Institute of Technology.
    Correction: Nonlinear electromagnetic wave equations for superdense magnetized plasmas (vol 16, 072114, 2009)2009In: PHYSICS OF PLASMAS, ISSN 1070-664X, Vol. 16, no 8Article in journal (Other academic)
    Abstract [en]

    n/a

  • 41.
    Shukla, Nitin
    et al.
    Umea University.
    Brodin, G
    Umea University.
    Marklund, M
    Umea University.
    Shukla, P K
    Umeå University.
    Stenflo, Lennart
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics . Linköping University, The Institute of Technology.
    Nonlinear electromagnetic wave equations for superdense magnetized plasmas2009In: PHYSICS OF PLASMAS, ISSN 1070-664X, Vol. 16, no 7Article in journal (Refereed)
    Abstract [en]

    By using the quantum hydrodynamic and Maxwell equations, we derive the generalized nonlinear electron magnetohydrodynamic, the generalized nonlinear Hall-MHD (HMHD), and the generalized nonlinear dust HMHD equations in a self-gravitating dense magnetoplasma. Our nonlinear equations include the self-gravitating, the electromagnetic, the quantum statistical electron pressure, as well as the quantum electron tunneling and electron spin forces. They are useful for investigating a number of wave phenomena including linear and nonlinear electromagnetic waves, as well as three-dimensional electromagnetic wave turbulence spectra and structures arising from mode coupling processes at nanoscales in dense quantum magnetoplasmas.

  • 42.
    Shukla, Nitin
    et al.
    Umeå University.
    Shukla, P K
    Ruhr University Bochum.
    Eliasson, B
    Ruhr University Bochum.
    Stenflo, Lennart
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics . Linköping University, The Institute of Technology.
    Magnetization of a quantum plasma by photons2010In: PHYSICS LETTERS A, ISSN 0375-9601, Vol. 374, no 15-16, p. 1749-1750Article in journal (Refereed)
    Abstract [en]

    It is shown that the ponderomotive force of large-amplitude electromagnetic waves (photons), which includes the electron spin current and exchange potential contributions in a quantum plasma, can generate magnetic fields. The present result can account for the magnetic fields in dense compact astrophysical objects and in the next generation laser-solid density plasma interaction experiments.

  • 43.
    Shukla, Nitin
    et al.
    Umeå University.
    Shukla, P K
    Ruhr University Bochum.
    Stenflo, Lennart
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics . Linköping University, The Institute of Technology.
    Magnetization of a warm plasma by the nonstationary ponderomotive force of an electromagnetic wave2009In: PHYSICAL REVIEW E, ISSN 1539-3755, Vol. 80, no 2, p. 027401-Article in journal (Refereed)
    Abstract [en]

    It is shown that magnetic fields can be generated in a warm plasma by the nonstationary ponderomotive force of a large-amplitude electromagnetic wave. In the present Brief Report, we derive simple and explicit results that can be useful for understanding the origin of the magnetic fields that are produced in intense laser-plasma interaction experiments.

  • 44.
    Shukla, Nitin
    et al.
    Umeå University.
    Shukla, P.K.
    Instituto Superior Tecnico.
    Brodin, G.
    Umeå University.
    Stenflo, Lennart
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics . Linköping University, The Institute of Technology.
    Ion streaming instability in a quantum dusty magnetoplasma2008In: Physics of Plasmas, ISSN 1070-664X, E-ISSN 1089-7674, Vol. 15, no 1070-664X, p. 044503-1-044503-3Article in journal (Refereed)
    Abstract [en]

    It is shown that a relative drift between the ions and the charged dust particles in a magnetized quantum dusty plasma can produce an oscillatory instability in a quantum dust acousticlike wave. The threshold and growth rate of the instability are presented. The result may explain the origin of low-frequency electrostatic fluctuations in semiconductors quantum wells. (C) 2008 American Institute of Physics.  

  • 45.
    Shukla, P K
    et al.
    Ruhr University Bochum.
    Eliasson, B
    Ruhr University Bochum.
    Stenflo, Lennart
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics . Linköping University, The Institute of Technology.
    Electromagnetic solitary pulses in a magnetized electron-positron plasma2011In: Physical Review E. Statistical, Nonlinear, and Soft Matter Physics, ISSN 1539-3755, E-ISSN 1550-2376, Vol. 84, no 3, p. 037401-Article in journal (Refereed)
    Abstract [en]

    A theory for large amplitude compressional electromagnetic solitary pulses in a magnetized electron-positron (e-p) plasma is presented. The pulses, which propagate perpendicular to the external magnetic field, are associated with the compression of the plasma density and the wave magnetic field. Here the solitary wave magnetic field pressure provides the restoring force, while the inertia comes from the equal mass electrons and positrons. The solitary pulses are formed due to a balance between the compressional wave dispersion arising from the curl of the inertial forces in Faradays law and the nonlinearities associated with the divergence of the electron and positron fluxes, the nonlinear Lorentz forces, the advection of the e-p fluids, and the nonlinear plasma current densities. The compressional solitary pulses can exist in a well-defined speed range above the Alfven speed. They can be associated with localized electromagnetic field excitations in magnetized laboratory and space plasmas composed of electrons and positrons.

  • 46.
    Shukla, P K
    et al.
    Ruhr University Bochum.
    Eliasson, B
    Ruhr University Bochum.
    Stenflo, Lennart
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics . Linköping University, The Institute of Technology.
    Large-amplitude Alfvenic shocks in a collisional magnetoplasma2011In: Europhysics letters, ISSN 0295-5075, E-ISSN 1286-4854, Vol. 95, no 4, p. 45001-Article in journal (Refereed)
    Abstract [en]

    A theory for large-amplitude Alfvenic shocks across the external magnetic field in a collisional magnetoplasma is presented. For this purpose, we use the continuity and momentum equations for the electrons and ions, together with Amperes and Faradays laws, to derive the governing nonlinear equations for large-amplitude compressional Alfvenic waves. It is found that the latter can appear in the form of large-amplitude Alfvenic shocks that propagate with the super-Alfvenic speed.

  • 47.
    Shukla, P K
    et al.
    Ruhr University of Bochum, Germany Ruhr University of Bochum, Germany University of Calif San Diego, CA 92093 USA University of Calif San Diego, CA 92093 USA .
    Eliasson, B
    Ruhr University of Bochum, Germany Ruhr University of Bochum, Germany .
    Stenflo, Lennart
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Nonlinear propagation of coherent electromagnetic waves in a dense magnetized plasma2012In: Physics of Plasmas, ISSN 1070-664X, E-ISSN 1089-7674, Vol. 19, no 7, p. 072302-Article in journal (Refereed)
    Abstract [en]

    We present an investigation of the nonlinear propagation of high-frequency coherent electromagnetic waves in a uniform quantum magnetoplasma. Specifically, we consider nonlinear couplings of right-hand circularly polarized electromagnetic-electron-cyclotron (CPEM-EC) waves with dispersive shear Alfven (DSA) and dispersive compressional Alfven (DCA) perturbations in plasmas composed of degenerate electron fluids and non-degenerate ion fluids. Such interactions lead to amplitude modulation of the CPEM-EC wave packets, the dynamics of which is governed by a three-dimensional nonlinear Schrodinger equation (NLSE) with the frequency shift arising from the relativistic electron mass increase in the CPEM-EC fields and density perturbations associated with the DSA and DCA perturbations. Accounting for the electromagnetic and quantum forces, we derive the evolution equation for the DSA and DCA waves in the presence of the magnetic field-aligned ponderomotive force of the CPEM-EC waves. The NLSE and the driven DSA and DCA equations are then used to investigate the modulational instability. The relevance of our investigation to laser-plasma interaction experiments and the cores of white dwarf stars is pointed out.

  • 48.
    Shukla, P K
    et al.
    Ruhr University of Bochum, Germany.
    Eliasson, B
    Ruhr University of Bochum, Germany.
    Stenflo, Lennart
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Stimulated scattering of electromagnetic waves carrying orbital angular momentum in quantum plasmas2012In: Physical Review E. Statistical, Nonlinear, and Soft Matter Physics, ISSN 1539-3755, E-ISSN 1550-2376, Vol. 86, no 1, p. 016403-Article in journal (Refereed)
    Abstract [en]

    We investigate stimulated scattering instabilities of coherent circularly polarized electromagnetic (CPEM) waves carrying orbital angular momentum (OAM) in dense quantum plasmas with degenerate electrons and nondegenerate ions. For this purpose, we employ the coupled equations for the CPEM wave vector potential and the driven (by the ponderomotive force of the CPEM waves) equations for the electron and ion plasma oscillations. The electrons are significantly affected by the quantum forces (viz., the quantum statistical pressure, the quantum Bohm potential, as well as the electron exchange and electron correlations due to electron spin), which are included in the framework of the quantum hydrodynamical description of the electrons. Furthermore, our investigation of the stimulated Brillouin instability of coherent CPEM waves uses the generalized ion momentum equation that includes strong ion coupling effects. The nonlinear equations for the coupled CPEM and quantum plasma waves are then analyzed to obtain nonlinear dispersion relations which exhibit stimulated Raman, stimulated Brillouin, and modulational instabilities of CPEM waves carrying OAM. The present results are useful for understanding the origin of scattered light off low-frequency density fluctuations in high-energy density plasmas where quantum effects are eminent.

  • 49.
    Shukla, P K
    et al.
    Ruhr University Bochum.
    Shukla, Nitin
    Umeå University.
    Stenflo, Lennart
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics . Linköping University, The Institute of Technology.
    Generation of magnetic fields by the ponderomotive force of electromagnetic waves in dense plasmas2010In: JOURNAL OF PLASMA PHYSICS, ISSN 0022-3778, Vol. 76, p. 25-28Article in journal (Refereed)
    Abstract [en]

    We show that the non-stationary ponderomotive force of a, large-amplitude electromagnetic move in a very dense quantum plasma wall streaming degenerate electrons can spontaneously create d.c. magnetic fields. The present result can account for the seed magnetic fields in compact astrophysical objects and in the next-generation intense laser-solid density, plasma interaction experiments.

  • 50.
    Shukla, P K
    et al.
    Ruhr University of Bochum, Germany Ruhr University of Bochum, Germany University of Calif San Diego, CA 92093 USA University of Calif San Diego, CA 92093 USA .
    Stenflo, Lennart
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Acoustic gravity tornadoes in the atmosphere2012In: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. 86, no 6Article in journal (Refereed)
    Abstract [en]

    It is shown that three-dimensional (3D) acoustic gravity waves (AGWs) in the atmosphere can appear in the form of acoustic gravity tornadoes (AGTs) characterized by twisted density structures or density ropes carrying orbital angular momentum. For our purposes, we use a previously obtained 3D wave equation for AGWs, and show that this equation in the paraxial approximation admits solutions in the form of Laguerre-Gauss acoustic gravity vortex beams or AGTs/AG whirls with twisted density structures supporting the dynamics of the AGTs.

12 1 - 50 of 77
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf