| 1. |
- Hobara, Y., et al.
(author)
-
Cluster observations of electrostatic solitary waves near the Earth's bow shock
- 2008
-
In: Journal of Geophysical Research. - 0148-0227 .- 2156-2202. ; 113:A5, s. A05211-
-
Journal article (peer-reviewed)abstract
- Using a period of internal burst mode data from the Cluster Electric Field and Wave instrument a number of electrostatic solitary structures have been identified in the foot region of Earth's quasi-perpendicular bow shock. The four individual probe potential measurements are utilized to investigate the fundamental characteristics of the solitary wave structures such as wave propagation vector, propagation velocity, scale-size and potential amplitude. Two classes of waves are observed. Bipolar solitary waves typically propagate in the solar wind direction toward the shock but at a significant angle from the ambient magnetic field. Unipolar/tripolar solitary waves tend to propagate along the ambient magnetic field. The wave amplitude-scale size relation is similar to that obtained for similar structures observed in the auroral zone. The structures lie in the theoretically allowed region in width-amplitude space to be consistent with the BGK ion holes. Using a period of internal burst mode data from the Cluster Electric Field and Wave instrument a number of electrostatic solitary structures have been identified in the foot region of Earth's quasi-perpendicular bow shock. The four individual probe potential measurements are utilized to investigate the fundamental characteristics of the solitary wave structures such as wave propagation vector, propagation velocity, scale-size and potential amplitude. Two classes of waves are observed. Bipolar solitary waves typically propagate in the solar wind direction toward the shock but at a significant angle to the ambient magnetic field in contrast to most previous studies which assume parallel propagation to the ambient magnetic field. In contrast, unipolar/tripolar solitary waves tend to propagate along the ambient magnetic field. The wave amplitude-scale size relation is similar to that obtained for structures observed in the auroral zone. The structures lie in the theoretically allowed region in width-amplitude space to be consistent with the BGK (Bernstein-Greene-Kruskal) ion holes. The two classes of observed solitary waves may greatly influence the ambient plasma dynamics around the shock. The bipolar solitary waves do not exhibit a large net potential difference but may still play an important role in plasma thermalisation by particle scattering. Unipolar/tripolar solitary waves exhibit a remarkable net potential difference that may be responsible for the plasma energisation along the ambient magnetic field.
|
|
| 2. |
- Kaladze, T D, et al.
(author)
-
Acoustic-gravity waves in the Earths ionosphere
- 2008
-
In: Journal of Atmospheric and Solar-Terrestrial Physics. - : Elsevier BV. - 1364-6826 .- 1879-1824. ; 70:13, s. 1607-1616
-
Journal article (peer-reviewed)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.
|
|
| 3. |
|
|
| 4. |
|
|
| 5. |
- Mendonca, J. T., et al.
(author)
-
Wave-kinetic description of atmospheric turbulence
- 2014
-
In: Physica Scripta. - : IOP Publishing. - 0031-8949 .- 1402-4896. ; 89, s. 125004-
-
Journal article (peer-reviewed)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.
|
|
| 6. |
- Onishchenko, O. G., et al.
(author)
-
Dust devil generation
- 2014
-
In: Physica Scripta. - : IOP Publishing: Hybrid Open Access. - 0031-8949 .- 1402-4896. ; 89:7, s. 075606-
-
Journal article (peer-reviewed)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.
|
|
| 7. |
- Onishchenko, O. G., et al.
(author)
-
Finite ion Larmor radius effects in magnetic curvature-driven Rayleigh-Taylor instability
- 2011
-
In: AIP Conference Proceeding Joint ITER-IAEA-ICTP Advanced Workshop on Fusion and Plasma Physics. - : American Institute of Physics (AIP). - 9780735410411 ; , s. 68-73
-
Conference paper (other academic/artistic)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.
|
|
| 8. |
|
|
| 9. |
|
|
| 10. |
|
|
| 11. |
|
|
| 12. |
|
|
| 13. |
- Onishchenko, O G, et al.
(author)
-
Stabilization of magnetic curvature-driven Rayleigh-Taylor instabilities
- 2012
-
In: Journal of Plasma Physics. - : Cambridge University Press (CUP). - 0022-3778 .- 1469-7807. ; 78, s. 93-97
-
Journal article (peer-reviewed)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.
|
|
| 14. |
|
|
| 15. |
- Onishchenko, O G, et al.
(author)
-
The magnetic Rayleigh-Taylor instability and flute waves at the ion Larmor radius scales
- 2011
-
In: PHYSICS OF PLASMAS. - : American Institute of Physics. - 1070-664X .- 1089-7674. ; 18:2, s. 022106-
-
Journal article (peer-reviewed)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.
|
|
| 16. |
|
|
| 17. |
|
|
| 18. |
|
|
| 19. |
- Pokhotelov, O.A., et al.
(author)
-
Physical mechanisms for electron mirror and field swelling modes
- 2013
-
In: Physica Scripta. - : Institute of Physics. - 0031-8949 .- 1402-4896. ; 87:6, s. 065303-
-
Journal article (peer-reviewed)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.
|
|
| 20. |
|
|
| 21. |
|
|
