| 1. |
- Anderson, D., et al.
(författare)
-
Collapse of optical vacuum pulses due to QED nonlinearities
- 2002
-
Ingår i: Nonlinear Guided Waves and Their Applications, 1–4 September 2002, Stresa, Italy. - : Optics Info Base, Optical Society of America. - 1557527237
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Due to quantum electrodynamical (QED) effects there are nonlinear corrections to Maxwell's equations in vacuum. We show that stationary two-dimensional light bullets can form, which are unstable and exhibit, the possibility of self-focusing collapse.
|
|
| 2. |
|
|
| 3. |
- Brodin, Gert, et al.
(författare)
-
A new decay channel for compressional Alfven waves in plasmas
- 2008
-
Ingår i: Journal of Plasma Physics. - 0022-3778 .- 1469-7807. ; 74:1, s. 99-105
-
Tidskriftsartikel (refereegranskat)abstract
- We present a new efficient wave decay channel involving nonlinear interactions between a compressional Alfv´en wave, a kinetic Alfv´en wave, and a modified ion sound wave in a magnetized plasma. It is found that the wave coupling strength of the ideal magnetohydrodynamic (MHD) theory is much increased when the effects due to the Hall current are included in a Hall–MHD description of wave–wave interactions. In particular, with a compressional Alfv´en pump wave well described by the ideal MHD theory, we find that the growth rate is very high when the decay products have wavelengths of the order of the ion thermal gyroradius or shorter, in which case they must be described by the Hall–MHD equations. The significance of our results to the heating of space and laboratory plasmas as well as for the Solar corona and interstellar media are highlighted.
|
|
| 4. |
- Brodin, Gert, et al.
(författare)
-
Anomalous reflection and excitation of surface waves in metamaterials
- 2007
-
Ingår i: Physics Letters A. - : Elsevier BV. - 0375-9601 .- 1873-2429. ; 367:3, s. 233-236
-
Tidskriftsartikel (refereegranskat)abstract
- We consider reflection of electromagnetic waves from layered structures with various dielectric and magnetic properties, including metamaterials. Assuming periodic variations in the permittivity, we find that the reflection is in general anomalous. In particular, we note that the specular reflection vanishes and that the incident energy is totally reflected in the backward direction, when the conditions for resonant excitation of leaking surface waves are fulfilled.
|
|
| 5. |
- Brodin, Gert, et al.
(författare)
-
Dispersion relation for electromagnetic wave propagation in a strongly magnetized plasma
- 2006
-
Ingår i: New Journal of Physics. - Bristol, UK : Institute of Physics Pub.. - 1367-2630. ; 8:January, s. 16-
-
Tidskriftsartikel (refereegranskat)abstract
- A dispersion relation for electromagnetic wave propagation in a strongly magnetized cold plasma is deduced, taking photon–photon scattering into account. It is shown that the combined plasma and quantum electrodynamic effect is important for understanding the mode-structures in magnetar and pulsar atmospheres. The implications of our results are discussed.
|
|
| 6. |
- Brodin, Gert, et al.
(författare)
-
Kinetic and quantum electrodynamical theory for circularly polarized waves in a plasma
- 2007
-
Ingår i: Physics Letters A. - : Elsevier. - 0375-9601 .- 1873-2429. ; 371, s. 462-
-
Tidskriftsartikel (refereegranskat)abstract
- The theory for large amplitude circularly polarized waves propagating along an external magnetic field is further developed. Relativistic effects, quantum electrodynamical effects due to vacuum polarization and magnetization, as well as kinetic effects are included in our formalism. A general dispersion relation, which unites previous results, is derived. As a specific example, a low-frequency kinetic mode with a detailed dependence on the electron distribution function is studied.
|
|
| 7. |
|
|
| 8. |
- Brodin, Gert, et al.
(författare)
-
Nonlinear interactions between three inertial Alfvén waves
- 2007
-
Ingår i: Journal of Plasma Physics. - 0022-3778 .- 1469-7807. ; 73:1, s. 9-13
-
Tidskriftsartikel (refereegranskat)abstract
- The resonant coupling between Alfvén waves is reconsidered. New results are found for cold agnetoplasmas where temperature effects are negligible.
|
|
| 9. |
- Brodin, Gert, 1963-, et al.
(författare)
-
On the parametric decay of waves in magnetized plasmas
- 2009
-
Ingår i: Journal of Plasma Physics. - Cambridge UK : Cambridge University Press. - 0022-3778 .- 1469-7807. ; 75, s. 9-13
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- 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.
|
|
| 10. |
|
|
| 11. |
|
|
| 12. |
|
|
| 13. |
|
|
| 14. |
|
|
| 15. |
|
|
| 16. |
- Dieckmann, Mark E, 1969-, et al.
(författare)
-
Simulation study of the filamentation of counter-streaming beams of the electrons and positrons in plasmas
- 2009
-
Ingår i: Plasma Physics and Controlled Fusion. - : Institute of Physics Publishing (IOPP). - 0741-3335 .- 1361-6587. ; 51:6
-
Tidskriftsartikel (refereegranskat)abstract
- 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.
|
|
| 17. |
- Eliasson, Bengt, et al.
(författare)
-
Full-Scale Numerical Modeling of Turbulent Processes in the Earth's Ionosphere
- 2008
-
Ingår i: Frontiers in Modern Plasma Physics. - : AIP. ; , s. 197-207
-
Konferensbidrag (refereegranskat)abstract
- We present a full-scale simulation study of ionospheric turbulence by means of a generalized Zakharov model based on the separation of variables into high-frequency and slow time scales. The model includes realistic length scales of the ionospheric profile and of the electromagnetic and electrostatic fields, and uses ionospheric plasma parameters relevant for high-latitude radio facilities such as Eiscat and HAARP. A nested grid numerical method has been developed to resolve the different length-scales, while avoiding severe restrictions on the time step. The simulation demonstrates the parametric decay of the ordinary mode into Langmuir and ion-acoustic waves, followed by a Langmuir wave collapse and short-scale caviton formation, as observed in ionospheric heating experiments.
|
|
| 18. |
- Eliasson, Bengt, et al.
(författare)
-
Full-scale simulation study of the initial stage of ionospheric turbulence
- 2008
-
Ingår i: Journal of Geophysical Research. - : American Geophysical Union (AGU). - 0148-0227 .- 2156-2202. ; 113:0148-0227, s. A02305-1-A02305-9
-
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.
|
|
| 19. |
- Eriksson, Daniel, et al.
(författare)
-
Possibility to measure elastic photon-photon scattering in vacuum
- 2004
-
Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 70:1, s. 013808-
-
Tidskriftsartikel (refereegranskat)abstract
- Photon-photon scattering in vacuum due to the interaction with virtual electron-positron pairs is a consequence of quantum electrodynamics. A way for detecting this phenomenon has been devised based on interacting modes generated in microwave wave guides or cavities [G. Brodin, M. Marklund, and L. Stenflo, Phys. Rev. Lett. 87, 171801 (2001)]. Here we materialize these ideas, suggest a concrete cavity geometry, make quantitative estimates and propose experimental details. It is found that detection of photon-photon scattering can be within the reach of present day technology.
|
|
| 20. |
|
|
| 21. |
- Gradov, O.M., et al.
(författare)
-
Non-linear effects in a cold electron plasma with non-uniform density profile
- 2008
-
Ingår i: Physica Scripta. - : IOP Publishing. - 0031-8949 .- 1402-4896. ; 77, s. 055503-1-055503-3
-
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.
|
|
| 22. |
|
|
| 23. |
|
|
| 24. |
- Kaladze, T D, et al.
(författare)
-
Acoustic-gravity waves in the Earths ionosphere
- 2008
-
Ingår i: Journal of Atmospheric and Solar-Terrestrial Physics. - : Elsevier BV. - 1364-6826 .- 1879-1824. ; 70:13, s. 1607-1616
-
Tidskriftsartikel (refereegranskat)abstract
- 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.
|
|
| 25. |
|
|
| 26. |
|
|
| 27. |
- Kaladze, T. D., et al.
(författare)
-
Zonal flow interaction with Rossby waves in the Earth's atmosphere : A numerical simulation
- 2008
-
Ingår i: Physics Letters A. - : Elsevier BV. - 0375-9601 .- 1873-2429. ; 372:31, s. 5177-5180
-
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
|
|
| 28. |
|
|
| 29. |
- Karimov, A R, et al.
(författare)
-
Coupled azimuthal and radial flows and oscillations in a rotating plasma
- 2009
-
Ingår i: PHYSICS OF PLASMAS. - : AIP Publishing. - 1070-664X .- 1089-7674. ; 16:6, s. 062313-
-
Tidskriftsartikel (refereegranskat)abstract
- 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.
|
|
| 30. |
- Karimov, A R, et al.
(författare)
-
Coupled flows and oscillations in asymmetric rotating plasmas
- 2009
-
Ingår i: PHYSICS OF PLASMAS. - : AIP Publishing. - 1070-664X .- 1089-7674. ; 16:10, s. 102303-
-
Tidskriftsartikel (refereegranskat)abstract
- 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]
|
|
| 31. |
|
|
| 32. |
- Lundin, Joakim, 1978-, et al.
(författare)
-
Circularly polarized waves in a plasma with vacuum polarization effects
- 2007
-
Ingår i: Physics of Plasmas. - : American Institute of Physics. - 1070-664X .- 1089-7674. ; 14:6, s. 064503-3 sidor
-
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.
|
|
| 33. |
|
|
| 34. |
|
|
| 35. |
|
|
| 36. |
- Marklund, Mattias, et al.
(författare)
-
Electrostatic pair creation and recombination in quantum plasmas
- 2006
-
Ingår i: JETP Letters. - 0021-3640 .- 1090-6487. ; 83:8, s. 313-317
-
Tidskriftsartikel (refereegranskat)abstract
- 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.
|
|
| 37. |
|
|
| 38. |
- Marklund, Mattias, et al.
(författare)
-
Fysiken bakom monstervågor
- 2006
-
Ingår i: Fysikaktuellt. - 0283-9148. ; :4, s. 6-7
-
Tidskriftsartikel (populärvet., debatt m.m.)
|
|
| 39. |
|
|
| 40. |
|
|
| 41. |
- Marklund, Mattias, et al.
(författare)
-
Magnetosonic solitons in a dusty plasma slab
- 2008
-
Ingår i: Journal of Plasma Physics. - Cambridge : Cambridge University Press. - 0022-3778 .- 1469-7807. ; 74:5, s. 601-605
-
Tidskriftsartikel (refereegranskat)abstract
- The existence of magnetosonic solitons in dusty plasmas is investigated. The nonlinear magnetohydrodynamic equations for a warm dusty magnetoplasma are thus derived. A solution of the nonlinear equations is presented. It is shown that, owing to the presence of dust, static structures are allowed. This is in sharp contrast to the formation of the so-called shocklets in usual magnetoplasmas. A comparatively small number of dust particles can thus drastically alter the behavior of the nonlinear structures in magnetized plasmas.
|
|
| 42. |
|
|
| 43. |
|
|
| 44. |
|
|
| 45. |
- Marklund, Mattias, et al.
(författare)
-
New quantum limits in plasmonic devices
- 2008
-
Ingår i: Europhysics letters. - Les Ulis : EDP Sciences. - 0295-5075 .- 1286-4854. ; 84:1
-
Tidskriftsartikel (refereegranskat)abstract
- 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.
|
|
| 46. |
- Marklund, Mattias, 1970-, et al.
(författare)
-
Nonlinear propagation of partially coherent dispersive Alfvén waves.
- 2006
-
Ingår i: Physica Scripta. - : INSTITUTE OF PHYSICS PUBLISHING. - 0031-8949 .- 1402-4896. ; 74:3, s. 373-376
-
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.
|
|
| 47. |
- Marklund, Mattias, et al.
(författare)
-
Quantum electrodynamical effects in dusty plasmas
- 2005
-
Ingår i: Physics of Plasmas. - Melville : American Institute of Physics (AIP). - 1070-664X .- 1089-7674. ; 12:7
-
Tidskriftsartikel (refereegranskat)abstract
- A new nonlinear electromagnetic wave mode in a magnetized dusty plasma is predicted. Its existence depends on the interaction of an intense circularly polarized electromagnetic wave with a dusty plasma, where quantum electrodynamical photon-photon scattering is taken into account. Specifically, we consider a dusty electron-positron-ion plasma and show that the propagation of the new mode is admitted. It could be of significance for the physics of supernova remnants and in neutron star formation.
|
|
| 48. |
|
|
| 49. |
|
|
| 50. |
|
|
