| 1. |
- Eliasson, Bengt, et al.
(författare)
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Full-scale simulation study of the initial stage of ionospheric turbulence
- 2008
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Ingår i: Journal of Geophysical Research. - : American Geophysical Union (AGU). - 0148-0227 .- 2156-2202. ; 113:0148-0227, s. A02305-1-A02305-9
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 2. |
- Gradov, O.M., et al.
(författare)
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Non-linear effects in a cold electron plasma with non-uniform density profile
- 2008
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Ingår i: Physica Scripta. - : IOP Publishing. - 0031-8949 .- 1402-4896. ; 77, s. 055503-1-055503-3
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 3. |
- Kaladze, T. D., et al.
(författare)
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Zonal flow interaction with Rossby waves in the Earth's atmosphere : A numerical simulation
- 2008
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Ingår i: Physics Letters A. - : Elsevier BV. - 0375-9601 .- 1873-2429. ; 372:31, s. 5177-5180
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Tidskriftsartikel (refereegranskat)abstract
- 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
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| 4. |
- Lundin, Joakim, 1978-, et al.
(författare)
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Circularly polarized waves in a plasma with vacuum polarization effects
- 2007
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Ingår i: Physics of Plasmas. - : American Institute of Physics. - 1070-664X .- 1089-7674. ; 14:6, s. 064503-3 sidor
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Tidskriftsartikel (refereegranskat)abstract
- The theory for large amplitude circularly polarized waves propagating along an external magnetic field is extended in order to also include vacuum polarization effects. A general dispersion relation, which unites previous results, is derived.
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| 5. |
- Marklund, Mattias, 1970-, et al.
(författare)
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Nonlinear propagation of partially coherent dispersive Alfvén waves.
- 2006
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Ingår i: Physica Scripta. - : INSTITUTE OF PHYSICS PUBLISHING. - 0031-8949 .- 1402-4896. ; 74:3, s. 373-376
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Tidskriftsartikel (refereegranskat)abstract
- The effects of partial coherence on the propagation of dispersive Alfvén waves in a magnetoplasma are investigated. In particular, nonlinear interactions between dispersive Alfvén waves and ion-acoustic perturbations are considered by means of a Wigner formalism. A set of governing equations consisting of a kinetic equation for dispersive Alfvén waves coupled nonlinearly to a ponderomotive force driven ion-acoustic wave equation is obtained. The governing nonlinear equations are used to derive a nonlinear dispersion relation that is appropriate for investigating the modulational instability of broadband Alfvén wavepackets. The spectral broadening of the Alfvén waves gives rise to new regimes for the growth rate of the modulational instability.
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| 6. |
- Shukla, Nitin, et al.
(författare)
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Ion streaming instability in a quantum dusty magnetoplasma
- 2008
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Ingår i: Physics of Plasmas. - : AIP Publishing. - 1070-664X .- 1089-7674. ; 15:1070-664X, s. 044503-1-044503-3
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 7. |
- Shukla, P.K., et al.
(författare)
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Modulational instabilities of surface plasmons on metallic plasma surfaces with nanoparticles
- 2008
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Ingår i: Journal of Plasma Physics. - 0022-3778 .- 1469-7807. ; 74:03, s. 287-291
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The nonlinear coupling between high-frequency surface plasmons (SPs) and low-frequency ion oscillations on metallic plasma surfaces with charged nanoparticles is considered. It is shown that a finite-amplitude SP wave is modulationally unstable against the excitation of non-resonant ion oscillations. The growth rates and thresholds of the modulational instabilities are presented.
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| 8. |
- Shukla, P.K., et al.
(författare)
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Quantum Hall-MHD equations for a non-uniform dense magnetoplasma with electron temperature anisotropy
- 2008
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Ingår i: Journal of Plasma Physics. - 0022-3778 .- 1469-7807. ; 74:05, s. 575-579
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Nonlinear quantum Hall-MHD equations for a warm dense magnetoplasma with an anisotropic electron pressure are derived. The nonlinear equations include the quantum force associated with electron tunneling effects. The newly found equations can be used to investigate the dense plasma stability, as well as different types of waves, instabilities, and nonlinear structures in a warm dense magnetoplasma.
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| 9. |
- Shukla, Padma, et al.
(författare)
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Wake field generation and nonlinear evolution in a magnetized electron-positron-ion plasma
- 2008
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Ingår i: Physics of Plasmas. - New York : AIP Publishing. - 1070-664X .- 1089-7674. ; 15:8, s. 082305-1-082305-4
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Tidskriftsartikel (refereegranskat)abstract
- The nonlinear propagation of a circularly polarized electromagnetic (CPEM) wave in a strongly magnetized electron-positron-ion plasma is investigated. Two coupled equations describing the interaction between a high-frequency CPEM wave and the low-frequency electrostatic wake field are derived. It is found that the generation of the wake fields partly depends on the presence of the ion species and the external magnetic field. The wake field generation in turn leads to deceleration and frequency down conversion of the electromagnetic pulse.
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| 10. |
- Shvartsburg, Alexander, et al.
(författare)
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Superluminal tunneling of microwaves in smoothly varying transmission lines
- 2008
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Ingår i: Physical Review E. Statistical, Nonlinear, and Soft Matter Physics. - New York : American Physical Society through the American Institute of Physics. - 1063-651X .- 1095-3787. ; 78, s. 016601-1-016601-6
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Tidskriftsartikel (refereegranskat)abstract
- Tunneling of microwaves through a smooth barrier in a transmission line is considered. In contrast to standard wave barriers, we study the case where the dielectric permittivity is positive, and the barrier is caused by the inhomogeneous dielectric profile. It is found that reflectionless, superluminal tunneling can take place for waves with a finite spectral width. The consequences of these findings are discussed, and an experimental setup testing our predictions is proposed.
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| 11. |
- Stenflo, Lennart, 1939-, et al.
(författare)
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Nonlinear Processes in Space Plasmas
- 2007
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Ingår i: Handbook of the Solar-Terrestrial Environment. - Berlin : Springer Berlin/Heidelberg. - 9783540463146 - 9783540463153 ; , s. 311-329
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- We present here a comprehensive review of some of the main nonlinear effects involving wave–wave and wave–particle interactions in space plasmas. Attention is focused on three-wave decay interactions, modulational instabilities, wave localization and the formation of structures caused by ponderomotive forces, differential electron Joule heating, and self-wave interactions of high- and low-frequency electromagnetic waves. We present nonlinear dispersion relations and their analysis, as well as the dynamics of nonlinearly interacting modes with the background plasma. The relevance of our investigation to space plasmas is discussed.
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