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/ D.B. Korovinskiy [et al.] // J. Geophys. Res-Space Phys. - 2013. - Vol. 118, Is. 3. - P1146-1158, DOI 10.1002/jgra.50206. - Cited References: 39. - This work is supported by the Austrian Science Fund (FWF): I193-N16, by the Onderzoekfonds KU Leuven (Research Fund KU Leuven), by RFBR Grants 12-05-00918-a and 12-05-00152-a, and by SPSU Grants 11.38.47.2011 and 11.38.84.2012. The research has received funding also from the European Union Seventh Framework Programme [FP7/2007-2013] under grant agreement 269198-Geoplasmas (Marie Curie International Research Staff Exchange Scheme) and 218816 (SOTERIA project). The simulations were conducted on the resources of the Vlaams Supercomputer Centrum (VSC) at the Katholieke Universiteit Leuven. N.V.E., V.S.S. and D.B.K. thank also ISSI for hospitality and financial support. The authors thank reviewers for their comments, which gave us the substantial aid in preparing of this manuscript. . - 13. - ISSN 2169-9380РУБ Astronomy & Astrophysics

Аннотация: The paper presents the detailed numerical investigation of the "double-gradient mode," which is believed to be responsible for the magnetotail flapping oscillations-the fast vertical (normal to the layer) oscillations of the Earth's magnetotail plasma sheet with a quasiperiod similar to 100-200 s. The instability is studied using the magnetotail near-equilibrium configuration. For the first time, linear three-dimensional numerical analysis is complemented with full 3-D MHD simulations. It is known that the "double-gradient mode" has unstable solutions in the region of the tailward growth of the magnetic field component, normal to the current sheet. The unstable kink branch of the mode is the focus of our study. Linear MHD code results agree with the theory, and the growth rate is found to be close to the peak value, provided by the analytical estimates. Full 3-D simulations are initialized with the numerically relaxed magnetotail equilibrium, similar to the linear code initial condition. The calculations show that current layer with tailward gradient of the normal component of the magnetic field is unstable to wavelengths longer than the curvature radius of the field line. The segment of the current sheet with the earthward gradient of the normal component makes some stabilizing effect (the same effect is registered in the linearized MHD simulations) due to the minimum of the total pressure localized in the center of the sheet. The overall growth rate is close to the theoretical double-gradient estimate averaged over the computational domain.

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Доп.точки доступа:
Korovinskiy, D.B.; Divin, A.; Erkaev, N.V.; Еркаев, Николай Васильевич; Ivanova, V.V.; Ivanov, I.B.; Semenov, V.S.; Lapenta, G.; Markidis, S.; Biernat, H.K.; Zellinger, M.

/ A. Divin [et al.] // J. Geophys. Res-Space Phys. - 2012. - Vol. 117. - Ст. A06217, DOI 10.1029/2011JA017464. - Cited References: 43. - The present work is supported partially by the Onderzoekfonds KU Leuven (Research Fund KU Leuven), by the NASA MMS grant NNX08AO84G and by the European Commission's Seventh Framework Programme (FP7/2007-2013) under the grant agreement 263340 (SWIFF project, www. swiff. eu) and 269198 - Geoplasmas (Marie Curie International Research Staff Exchange Scheme). Additional support is provided by RFBR grants 09-05-91000-ANF-a, 12-05-00152-a and 12-05-00918-a, Austrian Science Fund project T193-N16 and by SPSU grants 11.38.47.2011 and 11.38.84.2012. The simulations were conducted on the resources of the Vlaams Supercomputer Centrum (VSC) at the Katholieke Universiteit Leuven. The authors wish to thank the reviewers for their comments that helped to improve the manuscript. . - ISSN 2169-9380РУБ Astronomy & Astrophysics

Аннотация: The Sweet-Parker analysis of the inner electron diffusion region of collisionless magnetic reconnection is presented. The study includes charged particles motion near the X-line and an appropriate approximation of the off-diagonal term for the electron pressure tensor. The obtained scaling shows that the width of the inner electron diffusion region is equal to the electron inertial length, and that electrons are accelerated up to the electron Alfven velocity in X-line direction. The estimated effective plasma conductivity is based on the electron gyrofrequency rather than the binary collision frequency, and gives the extreme (minimal) value of the plasma conductivity similar to Bohm diffusion. The scaling properties are verified by means of Particle-in-Cell simulations. An ad hoc parameter needs to be introduced to the scaling relations in order to better match the theory and simulations.


Доп.точки доступа:
Divin, A.; Lapenta, G.; Markidis, S.; Semenov, V.S.; Erkaev, N.V.; Еркаев, Николай Васильевич; Korovinskiy, D.B.; Biernat, H.K.

[Text] / A. Divin [et al.] // Phys. Plasmas. - 2010. - Vol. 17, Is. 12. - Ст. 122102, DOI 10.1063/1.3521576. - Cited References: 42. - The present work is supported partially by the Onderzoekfonds KU Leuven (Research Fund KU Leuven) and by the European Commission's Seventh Framework Programme (FP7/2007-2013) under grant Agreement No. 218816 (SOTERIA project, www.soteria- space.eu). Additional support is provided by RFBR (Grant No. 09-05-91000-ANF-a). V.S.S. thanks ISSI for hospitality and financial support. The simulations were conducted on the resources of the Vlaams Supercomputer Centrum (VSC) at the Katholieke Universiteit Leuven. . - ISSN 1070-664XРУБ Physics, Fluids & Plasmas

Аннотация: A new model of the electron pressure anisotropy in the electron diffusion region in collisionless magnetic reconnection is presented for the case of antiparallel configuration of magnetic fields. The plasma anisotropy is investigated as source of collisionless dissipation. By separating electrons in the vicinity of the neutral line into two broad classes of inflowing and accelerating populations, it is possible to derive a simple closure for the off-diagonal electron pressure component. The appearance of these two electron populations near the neutral line is responsible for the anisotropy and collisionless dissipation in the magnetic reconnection. Particle-in-cell simulations verify the proposed model, confirming first the presence of two particle populations and second the analytical results for the off-diagonal electron pressure component. Furthermore, test-particle calculations are performed to compare our approach with the model of electron pressure anisotropy in the inner electron diffusion region by Fujimoto and Sydora [Phys. Plasmas 16, 112309 (2009)]. (C) 2010 American Institute of Physics. [doi:10.1063/1.3521576]


Доп.точки доступа:
Divin, A.; Markidis, S.; Lapenta, G.; Semenov, V.S.; Erkaev, N.V.; Еркаев, Николай Васильевич; Biernat, H.K.

[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] / D. B. Korovinskiy [et al.] // J. Geophys. Res-Space Phys. - 2008. - Vol. 113, Is. A4. - Ст. A04205, DOI 10.1029/2007JA012852. - Cited References: 56 . - ISSN 0148-0227РУБ Astronomy & Astrophysics

Аннотация: An analytical model of steady-state magnetic reconnection in a collisionless incompressible plasma is developed using the electron Hall MHD approximation. It is shown that the initial complicated system of equations may be split into a system of independent equations, and the solution of the problem is based on the solution of the Grad-Shafranov equation for a magnetic potential. This equation is found to be fundamental for the whole problem analysis. An electric field potential jump across the electron diffusion region and the separatrices is proved to be the necessary condition for steady- state reconnection. Besides of this fact, it is found that the protons in-plane motion obeys to Bernoulli law. The solution obtained demonstrates all essential Hall reconnection features, namely proton acceleration up to Alfven velocities and the formation of Hall current systems and a magnetic field structure as expected.


Доп.точки доступа:
Korovinskiy, D.B.; Semenov, V.S.; Erkaev, N.V.; Еркаев, Николай Васильевич; Divin, A.V.; Biernat, H.K.

[Text] / H. K. Biernat, N. V. Erkaev, C. J. Farrugia // J. Geophys. Res-Space Phys. - 1999. - Vol. 104, Is. A6. - P12617-12626, DOI 10.1029/1999JA900032. - Cited References: 37 . - ISSN 0148-0227РУБ Astronomy & Astrophysics

Аннотация: We describe the "magnetic string" approach to integrating the dissipationless magnetohydrodynamic (MHD) equations for flow around planetary obstacles and apply it to some aspects of the flow in the magnetosheath of Venus. Our method has both analytical and numerical components and is particularly suited to study the structure of the magnetic barrier (depletion layer). We do not include ion pickup processes and thus discuss only the contribution to the structure of the Venus magnetosheath made by the flow of the shocked solar wind. We work with an interplanetary magnetic field which is directed orthogonal to the solar wind bulk velocity. Magnetic forces on the flow are strongly dependent on the Alfven Mach number upstream of the bow shock, and one aim of this work is to study the dependence of field and flow quantities in the Venus magnetosheath on this parameter, thus allowing further future comparisons with data under a variety of interplanetary conditions. A second aim is to compare our MHD model results to a? synopsis of observations made by the Pioneer Venus Orbiter. As one main conclusion, we show that this method leads, in principle, to a standoff bow shock position in good agreement with observations. We find, namely, that for a low but reasonable Alfven Mach number, our MHD-modeled magnetosheath is only similar to 3.6% thinner in the Sun-Venus direction than that given by observations. Our method is complementary to three-dimensional, global MHD simulations of the solar wind-Venus interaction and offers versatility to modeling other aspects of the complicated interaction of the solar wind with Venus.


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

/ V. E. Zalizniak, O. A. Zolotov, I. I. Ryzhkov // J. Appl. Mech. Tech. Phys. - 2018. - Vol. 59, Is. 1. - P41-51, DOI 10.1134/S0021894418010066. - Cited References:32. - This work was supported by the Russian Science Foundation (Grant No. 15-19-10017). The calculations were performed at the Center of High-Performance Calculations of the Siberian Federal University. . - ISSN 0021-8944. - ISSN 1573-8620РУБ Mechanics + Physics, Applied

Аннотация: A model of ionic solutions is proposed which can be used to calculate aqueous salt solutions in different nanostructures. The interaction potential of the model includes the Lennard-Jones potential and angularly averaged dipole-dipole and ion-dipole interactions. Lennard-Jones potential parameters for different ions are obtained. Characteristics of aqueous solutions at different salt concentrations are calculated using the molecular dynamics method. It is shown that the calculated values of the hydration shells of ions parameters are in good agreement with the theoretical and experimental data at a salt concentration of 1 mol/kg. The computational scheme used in the calculations is described. It is shown that calculations using the proposed model require less computing resources compared with the standard models of ionic solutions.

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Держатели документа:
Siberian Fed Univ, Inst Math & Fundamental Informat, Krasnoyarsk 660041, Russia.
Russian Acad Sci, Inst Computat Modeling, Siberian Branch, Krasnoyarsk 660036, Russia.

Доп.точки доступа:
Zalizniak, V. E.; Zolotov, O. A.; Ryzhkov, I. I.; Russian Science Foundation [15-19-10017]

/ I. I. Ryzhkov, A. S. Vyatkin, M. I. Medvedeva // J. Sib. Fed. Univ.-Math. Phys. - 2019. - Vol. 12, Is. 5. - P579-589, DOI 10.17516/1997-1397-2019-12-5-579-589. - Cited References:32. - The reported study was funded by Russian Foundation for Basic Research, Government of Krasnoyarsk Territory, Krasnoyarsk Regional Fund of Science, to the research project 18-48-242011 "Mathematical modelling of synthesis and ionic transport properties of conductive nanoporous membranes". . - ISSN 1997-1397. - ISSN 2313-6022РУБ Mathematics

Аннотация: The impact of potential applied to the conductive surface of nanoporous membrane on the membrane potential at zero current is investigated theoretically on the basis of two-dimensional Space-charge model. The membrane separates two reservoirs with different salt concentrations. It is shown that the variation of applied potential from negative to positive values results in the continuous change of membrane selectivity from cation to anion. For equal ion diffusion coefficients, the dependence of membrane potential on the applied potential is an odd function, while for different ion diffusion coefficients it is shifted along the applied potential axis due to contribution of diffusion potential enhanced by the induced charge effect. The decrease of pore radius results in the increase of ionic selectivity and steep transition between cation- selective and anion-selective states when the applied potential is changing.

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Держатели документа:
Inst Computat Modelling SB RAS, Akademgorodok 50-44, Krasnoyarsk 660036, Russia.
Siberian Fed Univ, Svobodny 79, Krasnoyarsk 660041, Russia.

Доп.точки доступа:
Ryzhkov, Ilya I.; Vyatkin, Anton S.; Medvedeva, Maria, I; Russian Foundation for Basic Research, Government of Krasnoyarsk Territory, Krasnoyarsk Regional Fund of Science [18-48-242011]