Труды сотрудников ИВМ СО РАН

[Text] / H. Gunell [et al.] // Plasma Phys. Control. Fusion. - 2008. - Vol. 50, Is. 7. - Ст. 74018, DOI 10.1088/0741-3335/50/7/074018. - Cited References: 27 . - ISSN 0741-3335РУБ Physics, Fluids & Plasmas + Physics, Nuclear

Аннотация: We present measurements of oscillations in the electron density, ion density and ion velocity in the induced magnetosphere of Mars. The fundamental frequency of the oscillations is a few millihertz, but higher harmonics are present in the spectrum. The oscillations are observed in a region where there is a velocity shear in the plasma flow. The fundamental frequency is in agreement with computational results from an ideal-MHD model. An interpretation based on velocity-shear instabilities is described.


Доп.точки доступа:
Gunell, H.; Amerstorfer, U.V.; Nilsson, H.; Grima, C.; Koepke, M.; Franz, M.; Winningham, J.D.; Frahm, R.A.; Sauvaud, J.A.; Fedorov, A.; Erkaev, N.V.; Еркаев, Николай Васильевич; Biernat, H.K.; Holmstrom, M.; Lundin, R.; Barabash, S.

[Text] / C. J. Farrugia [et al.] // J. Geophys. Res-Space Phys. - 1997. - Vol. 102, Is. A6. - P11315-11324DOI 10.1029/97JA00410. - Cited References: 29 . - РУБ Astronomy & Astrophysics

Аннотация: Together with the magnetic shear across the magnetopause, the solar wind Alfven Mach number, M-A infinity plays a central role in determining the structure of the magnetosheath. Recent theoretical modeling has shown, in particular, that as M-A infinity decreases, the region adjacent to the sunward side of the magnetopause where the interplanetary magnetic field (IMF) exerts a strong influence on the flow (i.e., the so-called ''plasma depletion layer''), is no longer confined to a thin layer similar to 0.3 Earth radii (R-E) thick but occupies an increasingly larger fraction of the magnetosheath. Furthermore, the model predicts the possibility of a plasma depletion layer for low M-A infinity, irrespective of the size of the magnetic shear at the magnetopause, In this paper we study three examples of low latitude ISEE 2 passes through the dayside magnetosheath near noon: December 3, 1979; October 5, 1979; and November 11, 1979, In all three examples, MA, was lower than normal. During the December 3 pass (which we treat qualitatively), we find evidence of a plasma depletion layer when the IMF was pointing south, On the other two passes (which we study quantitatively), the interplanetary magnetic field was strongly northward pointing, leading to low magnetic shear at the respective magnetopause crossings, The October 5 pass was under steady interplanetary conditions and we find good agreement between theory and data, Temporal variations of the interplanetary medium during the November 11 pass necessitated an extension of the steady state theory to encompass piecewise steady (on average) interplanetary conditions, Better agreement with the data results when the theory is extended further to correct the total pressure at the sunward side of the magnetopause by integrating the magnetic tension term across the layer. For wide plasma depletion layers, this correction can be substantial.


Доп.точки доступа:
Farrugia, C.J.; Erkaev, N.V.; Еркаев, Николай Васильевич; Biernat, H.K.; Lawrence, G.R.; Elphic, R.C.

[Text] / N. V. Erkaev ; ed. M. I. Pudovkin [et al.] // PROBLEMS OF GEOSPACE : VERLAG OSTERREICHISCHEN AKAD WISSENSCHAFTEN, 1997. - International Conference on Problems of Geocosmos (JUN 17-23, 1996, PETRODVORETS, RUSSIA). - P91-100. - Cited References: 12 . - ISBN 3-7001-2676-XРУБ Astronomy & Astrophysics + Geochemistry & Geophysics + Geosciences, Multidisciplinary + Meteorology & Atmospheric Sciences

Аннотация: This article deals with a two-dimensional MHD model of a viscous-like plasma convection in the plasma sheet of the terrestrial magnetotail. In this model the role of viscous forces is mostly important inside the boundary layers adjacent to the magnetopause where the plasma sheet contacts with the solar wind how. A selfsimilar solution was obtained to describe the profiles of velocity and electric potential in the viscous boundary layers. This solution determines the boundary conditions for large scale electric potential and plasma convection in the plasma sheet. For zero IMF the plasma is convecting to the Earth in the central part of the sheet. The electric potential difference across the magnetotail in the equatorial plane depends on the effective viscous Reynolds number. A value of the Reynolds parameter of about 100 corresponds to the assumption that the distance between two effective collisions of ions is similar to the Larmor radius. This condition corresponds to a case of turbulent diffusion of ions in a magnetized plasma. For a nonzero IMF an additional electric field appears which is caused by reconnection of magnetic fields. In this case the resulting electric field in the tail is the sum of viscous-like and of reconnection fields. The plasma convection to the Earth increases for a southward IMF and decreases (or disappears) for a northward IMF.


Доп.точки доступа:
Erkaev, N.V.; Еркаев, Николай Васильевич; Pudovkin, M.I. \ed.\; Besser, B.P. \ed.\; Riedler, W. \ed.\; Riedler, . \ed.\