| 1. |
- Shukla, Nitin, et al.
(författare)
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Magnetization of a quantum plasma by photons
- 2010
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Ingår i: PHYSICS LETTERS A. - : Elsevier Science B.V., Amsterdam.. - 0375-9601 .- 1873-2429. ; 374:15-16, s. 1749-1750
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 2. |
- Shukla, Nitin, et al.
(författare)
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Nonlinear generation of zonal flows by ion-acoustic waves in a uniform magnetoplasma
- 2010
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Ingår i: Physics Letters A. - : Elsevier. - 0375-9601 .- 1873-2429. ; 374:4, s. 592-594
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Tidskriftsartikel (refereegranskat)abstract
- It is shown that large-scale zonal flows (ZFs) can be excited by Reynolds stress of nonlinearly interacting random phase ion-acoustic waves (EIAWs) in a uniform magnetoplasma. Since ZFs are associated with poloidal sheared flows, they can tear apart short scale EIAW turbulence eddies, and hence contribute to the reduction of the cross-field turbulent transport in a magnetized plasma. (C) 2009 Elsevier B.V. All rights reserved.
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| 3. |
- Shukla, Nitin, et al.
(författare)
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The dust acoustic wave in a bounded dusty plasma with strong electrostatic interactions between dust grains
- 2011
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Ingår i: Physics Letters A. - : Elsevier BV. - 0375-9601 .- 1873-2429. ; 375:17, s. 1809-1811
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Tidskriftsartikel (refereegranskat)abstract
- The dispersion relation for the dust acoustic wave (DAW) in an unmagnetized dusty plasma cylindrical waveguide is derived, accounting for strong electrostatic interactions between charged dust grains. It is found that the boundary effect limits the radial extent of the DAW. The present result should be helpful for understanding the frequency spectrum of the DAW in a dusty plasma waveguide with strongly coupled charged dust grains.
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| 4. |
- 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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| 5. |
- Eliasson, Bengt, et al.
(författare)
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Dispersion properties of electrostatic oscillations in quantum plasmas
- 2010
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Ingår i: Journal of Plasma Physics. - 0022-3778 .- 1469-7807. ; 76, s. 7-17
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Tidskriftsartikel (refereegranskat)abstract
- We present a derivation of the dispersion relation for electrostatic oscillations in a zero-temperature quantum plasma, in which degenerate electrons are governed by the Wigner equation, while non-degenerate ions follow the classical fluid equations. The Poisson equation determines the electrostatic wave potential. We consider parameters ranging from semiconductor plasmas to metallic plasmas and electron densities of compressed matter such as in laser compression schemes and dense astrophysical objects. Owing to the wave diffraction caused by overlapping electron wave function because of the Heisenberg uncertainty principle in dense plasmas, we have the possibility of Landau damping of the high-frequency electron plasma oscillations at large enough wavenumbers. The exact dispersion relations for the electron plasma oscillations are solved numerically and compared with the ones obtained by using approximate formulas for the electron susceptibility in the high- and low-frequency cases.
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| 6. |
- Eliasson, Bengt, et al.
(författare)
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Numerical investigation of the instability and nonlinear evolution of narrow-band directional ocean waves
- 2010
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Ingår i: Physical Review Letters. - New York : The American Physical Society. - 0031-9007 .- 1079-7114. ; 105:1, s. 014501-
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Tidskriftsartikel (refereegranskat)abstract
- The instability and nonlinear evolution of directional ocean waves is investigated numerically by means of simulations of the governing kinetic equation for narrow-band surface waves. Our simulation results reveal the onset of the modulational instability for long-crested wave trains, which agrees well with recent large-scale experiments in wave basins, where it was found that narrower directional spectra lead to self-focusing of ocean waves and an enhanced probability of extreme events. We find that the modulational instability is nonlinearly saturated by a broadening of the wave spectrum, which leads to the stabilization of the water-wave system. Applications of our results to other fields of physics, such as nonlinear optics and plasma physics, are discussed.
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| 7. |
- Fedele, Renato, et al.
(författare)
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Mathematical and physical aspects of controlling the exact solutions of the 3D Gross-Pitaevskii equation
- 2010
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Ingår i: Physics Letters A. - : Elsevier BV. - 0375-9601 .- 1873-2429. ; 374:5, s. 788-795
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Tidskriftsartikel (refereegranskat)abstract
- The possibility of the decomposition of the three-dimensional (3D) Gross–Pitaevskii equation (GPE) into a pair of coupled Schrödinger-type equations, is investigated. It is shown that, under suitable mathematical conditions, it is possible to construct the exact controlled solutions of the 3D GPE from the solutions of a linear 2D Schrödinger equation coupled with a 1D nonlinear Schrödinger equation (the transverse and longitudinal components of the GPE, respectively). The coupling between these two equations is the functional of the transverse and the longitudinal profiles. The applied method of nonlinear decomposition, called the controlling potential method (CPM), yields the full 3D solution in the form of the product of the solutions of the transverse and longitudinal components of the GPE. It is shown that the CPM constitutes a variational principle and sets up a condition on the controlling potential well. Its physical interpretation is given in terms of the minimization of the (energy) effects introduced by the control. The method is applied to the case of a parabolic external potential to construct analytically an exact BEC state in the form of a bright soliton, for which the quantitative comparison between the external and controlling potentials is presented.
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| 8. |
- Fedele, Renato, et al.
(författare)
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Soliton solutions of the 3D Gross-Pitaevskii equation by a potential control method
- 2010
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Ingår i: New Frontiers in Advanced Plasma Physics. - : AIP. - 9780735408623 ; , s. 61-74
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- We present a class of three-dimensional solitary waves solutions of the Gross-Pitaevskii (GP) equation, which governs the dynamics of Bose-Einstein condensates (BECs). By imposing an external controlling potential, a desired time-dependent shape of the localized BEC excitation is obtained. The stability of some obtained localized solutions is checked by solving the time-dependent GP equation numerically with analytic solutions as initial conditions. The analytic solutions can be used to design external potentials to control the localized BECs in experiment.
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| 9. |
- Masoud, Waqas, et al.
(författare)
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Electromagnetic wave equations for relativistically degenerate quantum magnetoplasmas
- 2010
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Ingår i: Physical Review E. Statistical, Nonlinear, and Soft Matter Physics. - New York : The American Physical Society. - 1063-651X .- 1095-3787. ; 81:6, s. 066401-5 pages
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Tidskriftsartikel (refereegranskat)abstract
- A generalized set of nonlinear electromagnetic quantum hydrodynamic (QHD) equations is derived for a magnetized quantum plasma, including collisional, electron spin-1/2, and relativistically degenerate electron pressure effects that are relevant for dense astrophysical systems, such as white dwarfs. For illustrative purposes, linear dispersion relations are derived for one-dimensional magnetoacoustic waves for a collisionless nonrelativistic degenerate gas in the presence of the electron spin-1/2 contribution and for magnetoacoustic waves in a plasma containing relativistically degenerate electrons. It is found that both the spin and relativistic degeneracy at high densities tend to slow down the magnetoacoustic wave due to the Pauli paramagnetic effect and relativistic electron mass increase. The present study outlines the theoretical framework for the investigation of linear and nonlinear behaviors of electromagnetic waves in dense astrophysical systems. The results are applied to calculate the magnetoacoustic speeds for both the nonrelativistic and relativistic electron degeneracy cases typical for white dwarf stars.
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| 10. |
- Misra, Amar P, et al.
(författare)
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Circularly polarized modes in magnetized spin plasmas
- 2010
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Ingår i: Journal of Plasma Physics. - 0022-3778 .- 1469-7807. ; 76:3/4, s. 857-864
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Tidskriftsartikel (refereegranskat)abstract
- The influence of the intrinsic spin of electrons on the propagation of circularly polarized waves in a magnetized plasma is considered. New eigenmodes are identified, one of which propagates below the electron cyclotron frequency, one above the spin-precession frequency, and another close to the spin-precession frequency. The latter corresponds to the spin modes in ferromagnets under certain conditions. In the non-relativistic motion of electrons, the spin effects become noticeable even when the external magnetic field B0 is below the quantum critical magnetic field strength, i.e. B0 < BQ = 4.4138 × 109T and the electron density satisfies n0 ≫ nc ≃ 1032m−3. The importance of electron spin (paramagnetic) resonance (ESR) for plasma diagnostics is discussed.
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