| 1. |
- Stenflo, Lennart, et al.
(författare)
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Nonlinear beam generated plasma waves as a source for enhanced plasma and ion acoustic lines
- 2011
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Ingår i: Physics of Plasmas. - : American Institute of Physics (AIP). - 1070-664X .- 1089-7674. ; 18:15, s. 052107-1-052107-14
-
Tidskriftsartikel (refereegranskat)abstract
- 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 Poisson's 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.
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| 2. |
- Anderson, D., et al.
(författare)
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Collapse of optical vacuum pulses due to QED nonlinearities
- 2002
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Ingår i: Nonlinear Guided Waves and Their Applications, 1–4 September 2002, Stresa, Italy. - : Optics Info Base, Optical Society of America. - 1557527237
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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.
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| 3. |
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| 4. |
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| 5. |
- Bingham, Robert, et al.
(författare)
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Ion acceleration by Alfven waves on auroral field lines
- 2013
-
Ingår i: Physica Scripta. - : Institute of Physics. - 0031-8949 .- 1402-4896. ; 87:5
-
Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 6. |
- Bingham, Robert, et al.
(författare)
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Solar coronal heating by plasma waves
- 2010
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Ingår i: Journal of Plasma Physics. - : Cambridge university. - 0022-3778 .- 1469-7807. ; 76:2, s. 135-158
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Tidskriftsartikel (refereegranskat)abstract
- The solar coronal plasma is maintained at temperatures of millions of degrees, much hotter than the photosphere, which is at a temperature of just 6000 K. In this paper, the plasma particle heating based on the kinetic theory of wave–particle interactions involving kinetic Alfvén waves and lower-hybrid drift modes is presented. The solar coronal plasma is collisionless and therefore the heating must rely on turbulent wave heating models, such as lower-hybrid drift models at reconnection sites or the kinetic Alfvén waves. These turbulent wave modes are created by a variety of instabilities driven from below. The transition region at altitudes of about 2000 km is an important boundary chromosphere, since it separates the collision-dominated photosphere/chromosphere and the collisionless corona. The collisionless plasma of the corona is ideal for supporting kinetic wave–plasma interactions. Wave–particle interactions lead to anisotropic non-Maxwellian plasma distribution functions, which may be investigated by using spectral analysis procedures being developed at the present time.
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| 7. |
- Brodin, Gert, et al.
(författare)
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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.
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| 8. |
- Brodin, Gert, et al.
(författare)
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A new decay channel for upper-hybrid waves
- 2016
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Ingår i: Physica Scripta. - : IOP Publishing. - 0031-8949 .- 1402-4896. ; 91:10
-
Tidskriftsartikel (refereegranskat)abstract
- We look here at a three-wave interaction process involving only electrostatic waves in an electron plasma with stationary ions. Special attention is given to the case with an upper-hybrid wave as a pump wave, where a new decay channel is pointed out. The corresponding growth rate is calculated.
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| 9. |
- Brodin, Gert, et al.
(författare)
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A simple electron plasma wave
- 2017
-
Ingår i: Physics Letters A. - : Elsevier BV. - 0375-9601 .- 1873-2429. ; 381:11, s. 1033-1035
-
Tidskriftsartikel (refereegranskat)abstract
- Considering a class of solutions where the density perturbations are functions of time, but not of space, we derive a new exact large amplitude wave solution for a cold uniform electron plasma. This result illustrates that most simple analytical solutions can appear even if the density perturbations are large.
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| 10. |
- Brodin, Gert, et al.
(författare)
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Alfven wave interactions within the Hall-MHD description
- 2013
-
Ingår i: Journal of Plasma Physics. - : Cambridge University Press (CUP). - 0022-3778 .- 1469-7807. ; 79, s. 909-911
-
Tidskriftsartikel (refereegranskat)abstract
- We show that comparatively simple expressions for the Alfven wave coupling coefficients can be deduced from the well-known Hall-magnetohydrodynamics (MHD) model equations.
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| 11. |
- Brodin, Gert, et al.
(författare)
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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.
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| 12. |
- Brodin, Gert, et al.
(författare)
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Dispersion relation for electromagnetic wave propagation in a strongly magnetized plasma
- 2006
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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.
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| 13. |
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| 14. |
- Brodin, Gert, et al.
(författare)
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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.
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| 15. |
- Brodin, Gert, et al.
(författare)
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Large amplitude electron plasma oscillations
- 2014
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Ingår i: Physics Letters A. - : Elsevier. - 0375-9601 .- 1873-2429. ; 378:22-23, s. 1632-1635
-
Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 16. |
- Brodin, Gert, et al.
(författare)
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Nonlinear dynamics of a cold collisional electron plasma
- 2017
-
Ingår i: Physics of Plasmas. - : AIP Publishing. - 1070-664X .- 1089-7674. ; 24:12
-
Tidskriftsartikel (refereegranskat)abstract
- We study the influence of collisions on the dynamics of a cold non-relativistic plasma. It is shown that even a comparatively small collision frequency can significantly change the large amplitude wave solution.
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| 17. |
- Brodin, Gert, et al.
(författare)
-
Nonlinear dynamics of large amplitude modes in a magnetized plasma
- 2014
-
Ingår i: Physics of Plasmas. - : AIP Publishing. - 1070-664X .- 1089-7674. ; 21:12
-
Tidskriftsartikel (refereegranskat)abstract
- We derive two equations describing the coupling between electromagnetic and electrostatic oscillations 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 electromagnetic polarization are of particular interest here. New results can, thus, be identified.
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| 18. |
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| 19. |
- 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.
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| 20. |
- Brodin, Gert, et al.
(författare)
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Nonlinear wave interactions of kinetic sound waves
- 2015
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Ingår i: Annales Geophysicae. - : Copernicus GmbH. - 0992-7689 .- 1432-0576. ; 33:8, s. 1007-1010
-
Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 21. |
- 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.
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| 22. |
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| 23. |
- Brodin, Gert, 1963-, et al.
(författare)
-
Stimulated Brillouin scattering in magnetized plasmas
- 2013
-
Ingår i: Journal of Plasma Physics. - : Cambridge University Press. - 0022-3778 .- 1469-7807. ; 79:Special Issue 06, s. 983-986
-
Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 24. |
- Brodin, Gert, et al.
(författare)
-
Three-wave coupling coefficients for a magnetized plasma
- 2012
-
Ingår i: Physica Scripta. - Bristol : Institute of Physics. - 0031-8949 .- 1402-4896. ; 85:3, s. 035504-
-
Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 25. |
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| 26. |
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| 27. |
- Brodin, Gert, et al.
(författare)
-
Three-wave coupling coefficients for perpendicular wave propagation in a magnetized plasma
- 2015
-
Ingår i: Physics of Plasmas. - : AIP Publishing. - 1070-664X .- 1089-7674. ; 22:10
-
Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 28. |
- Brodin, Gert, et al.
(författare)
-
Wave Generation in a Warm Magnetized Multi-Component Plasma
- 2014
-
Ingår i: Contributions to Plasma Physics. - : Wiley. - 0863-1042 .- 1521-3986. ; 54:7, s. 623-625
-
Tidskriftsartikel (refereegranskat)abstract
- 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. (C) 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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| 29. |
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| 30. |
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| 31. |
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| 32. |
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| 33. |
- Dieckmann, Mark E, 1969-, et al.
(författare)
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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.
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| 34. |
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| 35. |
- Eliasson, Bengt, et al.
(författare)
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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.
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| 36. |
- Eliasson, Bengt, et al.
(författare)
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Full-scale simulation study of stimulated electromagnetic emissions: The first ten milliseconds
- 2010
-
Ingår i: JOURNAL OF PLASMA PHYSICS. - : Cambridge University Press. - 0022-3778 .- 1469-7807. ; 76, s. 369-375
-
Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 37. |
- 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.
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| 38. |
- Eliasson, B, et al.
(författare)
-
Preface to special issue
- 2013
-
Ingår i: Journal of Plasma Physics. - : Cambridge University Press. - 0022-3778 .- 1469-7807. ; 79:6, s. 981-981
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- 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.
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| 39. |
- Eriksson, Daniel, et al.
(författare)
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Possibility to measure elastic photon-photon scattering in vacuum
- 2004
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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.
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| 40. |
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| 41. |
- Gradov, O. M., et al.
(författare)
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Basic properties of nonlinear surface charge waves at a plasma boundary
- 2018
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Ingår i: Physics Letters A. - : ELSEVIER SCIENCE BV. - 0375-9601 .- 1873-2429. ; 42-43, s. 3083-3085
-
Tidskriftsartikel (refereegranskat)abstract
- The nonlinear properties of surface charges are here analyzed under ideal conditions. We thus deduce a new single equation from the wellknown equations which govern the cold electron plasma motion. Simple formulas that describe the propagation of surface charge perturbations along the plasma boundary are also found. (C) 2018 Elsevier B.V. All rights reserved.
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| 42. |
- Gradov, O.M., et al.
(författare)
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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.
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| 43. |
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| 44. |
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| 45. |
-
Journal of Plasma Physics vol 76 issue 3-4 : special issue in honor of professor Padma Kant Shukla on the occasion of his 60th birthday
- 2010. - 76
-
Proceedings (redaktörskap) (övrigt vetenskapligt/konstnärligt)abstract
- It is our great pleasure to dedicate this special issue of Journal of Plasma Physics to our dear friend and colleague Professor Padma Kant Shukla on the occasion of his 60th birthday on 7th July 2010. Padma is one of the most prominent and productive scientists in plasma physics and in neighboring fields, and has published more than 1300 papers in scientific journals. It has for some time been the aim of his friends to honor him on this occasion, and earlier this year we sent out invitations to distinguished scientists who have collaborated with Padma over the years. The response has been overwhelming, and we collected 43 manuscripts, covering a diverse range of topics in plasma physics, which are now published in this issue. We believe that these papers reflect some of the impact of Padma's research in plasma physics.
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| 46. |
- Kaladze, T D, et al.
(författare)
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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.
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| 47. |
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| 48. |
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| 49. |
- 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
-
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
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| 50. |
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