| 1. |
- 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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| 2. |
- Al-Naseri, Haidar, et al.
(författare)
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Linear pair-creation damping of high-frequency plasma oscillation
- 2022
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Ingår i: Physics of Plasmas. - : American Institute of Physics (AIP). - 1070-664X .- 1089-7674. ; 29:4
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Tidskriftsartikel (refereegranskat)abstract
- We have studied the linear dispersion relation for Langmuir waves in plasmas of very high density, based on the Dirac-Heisenberg-Wigner formalism. The vacuum contribution to the physical observables leads to ultraviolet divergences, which are removed by a charge renormalization. The remaining vacuum contribution is small and is in agreement with previously derived expressions for the time-dependent vacuum polarization. The main new feature of the theory is a damping mechanism similar to Landau damping, but where the plasmon energy gives rise to creation of electron-positron pairs. The dependence of the damping rate (pair-creation rate) on the wavenumber, temperature, and density is analyzed. Finally, the analytical results of linearized theory are compared with numerical solutions.
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| 3. |
- Al-Naseri, Haidar, 1993-, et al.
(författare)
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Ponderomotive force due to the intrinsic spin for electrostatic waves in a magnetized plasma
- 2023
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Ingår i: Physics of Plasmas. - : American Institute of Physics (AIP). - 1070-664X .- 1089-7674. ; 30:6
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Tidskriftsartikel (refereegranskat)abstract
- We study the contribution from the electron spin to the ponderomotive force, using a quantum kinetic model, including the spin-orbit correction. Specifically, we derive an analytical expression for the ponderomotive force, applicable for electrostatic waves propagating parallel to an external magnetic field. To evaluate the expression, we focus on the case of Langmuir waves and on the case of the spin resonance wave mode, where the classical and spin contributions to the ponderomotive force are compared. Somewhat surprisingly, depending on the parameter regime, we find that the spin contribution to the ponderomotive force may dominate for the Langmuir wave, whereas the classical contribution can dominate for the spin resonance mode.
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| 4. |
- Brodin, Gert, 1963-, et al.
(författare)
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Do hydrodynamic models based on time-independent density functional theory misestimate exchange effects? : Comparison with kinetic theory for electrostatic waves
- 2019
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Ingår i: Physics of Plasmas. - : American Institute of Physics (AIP). - 1070-664X .- 1089-7674. ; 26:9
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Tidskriftsartikel (refereegranskat)abstract
- We have extended previous quantum kinetic results to compute the exchange correction to the electrostatic electron susceptibility for arbitrary frequencies and wavenumbers in the low temperature limit. This has allowed us to make a general comparison with a much used hydrodynamic expression, based on density functional theory, for exchange effects. For low phase velocities, as for ion-acoustic waves, wave-particle interaction leads to a strong enhancement of the exchange correction and the hydrodynamic result is smaller by an order of magnitude. The hydrodynamic expression gives a useful approximation when the phase velocity is 2.5 times the Fermi velocity. If this condition is not fulfilled, the hydrodynamical theory gives misleading results. We discuss the implications of our results for the model choice for quantum plasmas, especially regarding particle dispersive effects.
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| 5. |
- Brodin, Gert, et al.
(författare)
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Nonlinear dynamics of a cold collisional electron plasma
- 2017
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Ingår i: Physics of Plasmas. - : AIP Publishing. - 1070-664X .- 1089-7674. ; 24:12
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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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| 6. |
- Brodin, Gert, et al.
(författare)
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Nonlinear dynamics of large amplitude modes in a magnetized plasma
- 2014
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Ingår i: Physics of Plasmas. - : AIP Publishing. - 1070-664X .- 1089-7674. ; 21:12
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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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| 7. |
- Brodin, Gert, et al.
(författare)
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Spin solitons in magnetized pair plasmas
- 2007
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Ingår i: Physics of Plasmas. - : AIP Publishing. - 1070-664X .- 1089-7674. ; 14:11, s. 2107-4 sidor
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Tidskriftsartikel (refereegranskat)abstract
- A set of fluid equations, taking into account the spin properties of the electrons and positrons in a magnetoplasma, are derived. The magnetohydrodynamic limit of the pair plasma is investigated. It is shown that the microscopic spin properties of the electrons and positrons can lead to interesting macroscopic and collective effects in strongly magnetized plasmas. In particular, it is found that new Alfvénic solitary structures, governed by a modified Korteweg–de Vries equation, are allowed in such plasmas. These solitary structures vanish if the quantum spin effects are neglected. Our results should be of relevance for astrophysical plasmas, e.g., in pulsar magnetospheres, as well as for low-temperature laboratory plasmas.
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| 8. |
- Brodin, Gert, et al.
(författare)
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Three-wave coupling coefficients for perpendicular wave propagation in a magnetized plasma
- 2015
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Ingår i: Physics of Plasmas. - : AIP Publishing. - 1070-664X .- 1089-7674. ; 22:10
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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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| 9. |
- Hussain, Azhar, et al.
(författare)
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Weakly relativistic quantum kinetic theory for electrostatic wave modes in magnetized plasmas
- 2014
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Ingår i: Physics of Plasmas. - : AIP Publishing LLC. - 1070-664X .- 1089-7674. ; 21:3, s. 032104-
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Tidskriftsartikel (refereegranskat)abstract
- We have derived the electrostatic dispersion relation in a magnetized plasma using a recently developed quantum kinetic model based on the Dirac equation. The model contains weakly relativistic spin effects such as Thomas precession, the polarization currents associated with the spin and the spin-orbit coupling. It turns out that for strictly electrostatic perturbations the non-relativistic spin effects vanish, and the modification of the classical dispersion relation is solely associated with the relativistic terms. Several new wave modes appear due the electron spin effects, and an example for astrophysical plasmas are given. (C) 2014 AIP Publishing LLC.
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| 10. |
- Jenab, Seyyed Mehdi Hosseini, et al.
(författare)
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A study of the stability properties of Sagdeev solutions in the ion-acoustic regime using kinetic simulations
- 2018
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Ingår i: Physics of Plasmas. - : AIP Publishing. - 1070-664X .- 1089-7674. ; 25:7
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Tidskriftsartikel (refereegranskat)abstract
- The Sagdeev pseudo-potential approach has been employed extensively in theoretical studies to determine large-amplitude (fully) nonlinear solutions in a variety of multi-species plasmas. Although these solutions are repeatedly considered as solitary waves (and even solitons), their temporal stability has never been proven. In this paper, a numerical study of the Vlasov-Poisson system is made to follow their temporal evolution in the presence of numerical noise and thereby test their long-time propagation stability. Considering the ion-acoustic regime, both constituents of the plasma, i.e., electrons and ions are treated following their distribution functions in these sets of fully-kinetic simulations. The findings reveal that the stability of the Sagdeev solution depends on a combination of two parameters, i.e., velocity and trapping parameter. It is shown that there exists a critical value of trapping parameter for both fast and slow solutions which separates stable from unstable solutions. In the case of stable solutions, it is shown that these nonlinear structures can propagate for long periods, which confirms their status as solitary waves. Stable solutions are reported for both Maxwellian and Kappa distribution functions. For unstable solutions, it is demonstrated that the instability causes the Sagdeev solution to decay by emitting ion-acoustic wave-packets on its propagation trail. The instability is shown to take place in a large range of velocities and even for Sagdeev solutions with a velocity much higher than the ion-sound speed. Besides, in order to validate our simulation code, two precautionary measures are taken. First, the well-known effect of the ion dynamics on a stationary electron hole solution is presented as a benchmarking test of the approach. Second, In order to verify the numerical accuracy of the simulations, the conservation of energy and entropy is presented.
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