| 1. |
|
|
| 2. |
- Mendonca, J. T., et al.
(författare)
-
Wave-kinetic description of atmospheric turbulence
- 2014
-
Ingår i: Physica Scripta. - : IOP Publishing. - 0031-8949 .- 1402-4896. ; 89, s. 125004-
-
Tidskriftsartikel (refereegranskat)abstract
- We propose a wave-kinetic description of atmospheric turbulence, where the turbulence spectrum is described as a gas of quasi-particles. We apply this description to the case of zonal structures in the atmosphere, which can be excited by internal gravity wave turbulence. A general expression for the instability growth rates is derived, and the particular example of a nearly mono-kinetic turbulent spectrum is discussed.
|
|
| 3. |
- Onishchenko, O. G., et al.
(författare)
-
Dust devil generation
- 2014
-
Ingår i: Physica Scripta. - : IOP Publishing: Hybrid Open Access. - 0031-8949 .- 1402-4896. ; 89:7, s. 075606-
-
Tidskriftsartikel (refereegranskat)abstract
- The equations describing axi-symmetric nonlinear internal gravity waves in an unstable atmosphere are derived. A hydrodynamic model of a dust devil generation mechanism in such an atmosphere is investigated. It is shown that in an unstably stratified atmosphere the convective plumes with poloidal motion can grow exponentially. Furthermore, it is demonstrated that these convective plumes in an atmosphere with weak large scale toroidal motion are unstable with respect to three-dimensional dust devil generation.
|
|
| 4. |
- Onishchenko, O. G., et al.
(författare)
-
Finite ion Larmor radius effects in magnetic curvature-driven Rayleigh-Taylor instability
- 2011
-
Ingår i: AIP Conference Proceeding Joint ITER-IAEA-ICTP Advanced Workshop on Fusion and Plasma Physics. - : American Institute of Physics (AIP). - 9780735410411 ; , s. 68-73
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Incomplete finite ion Larmor radius stabilization of the magnetic Rayleigh-Taylor (RT)instability is investigated. In contrast to the previous studies the effects of both the gravity and magnetic field curvature are taken into account. New model hydrodynamic equations describing nonlinear flute waves with arbitrary spatial scales have been derived. Particular attention is paid to the waves with spatial scales of the order of the ion Larmor radius. In the linear approximation a Fourier transform of these equations yields a generalized dispersion relation for flute waves. The condition for gravity and magnetic curvature at which the instability cannot be stabilized by the finite ion Larmor radius effects is found. It is shown that in the absence of the magnetic curvature the complete stabilization arises due to the cancellation of gravitational and diamagnetic drifts. However, when the magnetic curvature drift is taken into account this synchronization is violated and the RT instability is stabilized at more complex conditions. Furthermore, the dependence of the instability growth rate on the equilibrium plasma parameters is investigated.
|
|
| 5. |
|
|
| 6. |
|
|
| 7. |
|
|
| 8. |
|
|
| 9. |
|
|
| 10. |
- Onishchenko, O G, et al.
(författare)
-
Stabilization of magnetic curvature-driven Rayleigh-Taylor instabilities
- 2012
-
Ingår i: Journal of Plasma Physics. - : Cambridge University Press (CUP). - 0022-3778 .- 1469-7807. ; 78, s. 93-97
-
Tidskriftsartikel (refereegranskat)abstract
- The finite ion Larmor radius (FLR) stabilization of the magnetic curvature-driven Rayleigh Taylor (MCD RT) instability in a low beta plasma with nonzero ion temperature gradient is investigated. Finite electron temperature effects and ion temperature perturbations are incorporated. A new set of nonlinear equations for flute waves with arbitrary wavelengths as compared with the ion Larmor radius in a plasma with curved magnetic field lines is derived. Particular attention is paid to the waves with spatial scales of the order of the ion Larmor radius. In the linear limit, a Fourier transform of these equations yields an improved dispersion relation for flute waves. The dependence of the M CD RT instability growth rate on the equilibrium plasma parameters and the wavelengths is studied. The condition for which the instability cannot be stabilized by the FLR effects is found.
|
|
| 11. |
|
|
| 12. |
- Onishchenko, O G, et al.
(författare)
-
The magnetic Rayleigh-Taylor instability and flute waves at the ion Larmor radius scales
- 2011
-
Ingår i: PHYSICS OF PLASMAS. - : American Institute of Physics. - 1070-664X .- 1089-7674. ; 18:2, s. 022106-
-
Tidskriftsartikel (refereegranskat)abstract
- The theory of flute waves (with arbitrary spatial scales compared to the ion Larmor radius) driven by the Rayleigh-Taylor instability (RTI) is developed. Both the kinetic and hydrodynamic models are considered. In this way we have extended the previous analysis of RTI carried out in the long wavelength limit. It is found that complete finite ion Larmor radius stabilization is absent when the ion diamagnetic velocity attains the ion gravitation drift velocity. The hydrodynamic approach allowed us to deduce a new set of nonlinear equations for flute waves with arbitrary spatial scales. It is shown that the previously deduced equations are inadequate when the wavelength becomes of the order of the ion Larmor radius. In the linear limit a Fourier transform of these equations yields the dispersion relation which in the so-called Pade approximation corresponds to the results of the fully kinetic treatment. The development of such a theory gives us enough grounds for an adequate description of the RTI stabilization by the finite ion Larmor radius effect.
|
|
| 13. |
|
|
| 14. |
|
|
| 15. |
|
|
| 16. |
- Pokhotelov, O.A., et al.
(författare)
-
Physical mechanisms for electron mirror and field swelling modes
- 2013
-
Ingår i: Physica Scripta. - : Institute of Physics. - 0031-8949 .- 1402-4896. ; 87:6, s. 065303-
-
Tidskriftsartikel (refereegranskat)abstract
- Ion mirror instability is dominant in planetary and cometary magnetosheaths and other high-beta plasmas where the ions are hotter than the electrons. It is associated with a zero-frequency non-propagating mode with the wave vector nearly perpendicular to the ambient magnetic field. The counterparts of this instability in hot electron plasmas are the field swelling and electron mirror instabilities. A theory for these instabilities was developed more than two decades ago (Basu B and Coppi B 1982 Phys. Rev. Lett. 48 799, 1984 Phys. Fluids 27 1187) within the framework of a fluid model. The connection between the two types of instabilities has been analyzed in (Migliuolo S 1986 J. Geophys. Res. 91 7981). In contrast to these papers, we shall here adopt the standard quasi-hydrodynamic approach that is usually used for the study of mirror instabilities. To analyze the electron mirror and field swelling instabilities, we will only use the perpendicular balance condition and the Liouville theorem. We have found that such a description is easier to understand and gives us increased physical insight into the basic physical features of both these instabilities.
|
|
| 17. |
|
|
