arXiv subjects

P. A. Sedykh

Publications and source records attributed to P. A. Sedykh.

7 recordsLinked to original sources

arXiv2019

Interstellar medium parameters in front of the external bow shock

We know that it is the front of the bow shock where the solar wind kinetic energy flux is transformed into the other kinds the most intensively. In our previous studies, we obtained important relationships that enable calculating the key parameters at transition through the bow shock front. One of the most important sources of information on physical processes at the heliosphere boundary are the Voyager 1 and 2 spacecrafts. Since both the solar wind and interstellar medium are supersonic streams, two shocks are formed when flowing around the heliopause. The internal shock, in which the solar wind decelerates to subsonic velocity, is called the heliospheric shock. In the external bow shock, the interstellar gas supersonic flux is decelerated. The aim of this paper is to generalize the previously obtained equations to the processes in the external bow shock region. If Voyager-1 was equipped with a greater set of measuring instruments, we could have already provided estimations of the interstellar medium key parameters, and described in physical terms what this medium is, using relationships and equations from our studies.

physics.space-ph↗

arXiv2017

Power aspects of processes at the piston shock region

Identifying blast-wave shocks, which can arise during CME formation, is a much more complex problem. The difference from piston shocks is that a blast-wave shock originates from the explosions that frequently accompany CME formation, and further propagates freely without any CME piston effects. The bow shock of Earth is a piston shock. Behind the bow shock front there is a flow of the modified solar wind plasma: transition layer, which also carries the modified magnetic field of solar wind. Velocity and density of plasma as well as parameters of magnetic field of this current can be estimated if the form of the bow shock front and of magnetopause are considered to be known. In this paper we assumed them to be paraboloids of rotation. In this paper we have determined potential distribution along magnetopause from the balance condition of substance coming into transition layer from the solar wind on one side and leaving through the gap between magnetosphere and the bow shock front and through magnetopause on another. To a first approximation this distribution differs from potential distribution at the BS front only in a constant multiplier. We used the established potential distribution as a boundary condition while solving the problem on potential distribution in the magnetosphere. The first solution harmonic turned out to coincide in the form with the boundary condition on magnetopause. We have constructed the full solution for electric field in the magnetosphere having limited ourselves to the first harmonic and corotation field. We have obtained necessary equations to model processes in the region of bow shock.

physics.space-ph↗

arXiv2017

Equivalent electric circuit of magnetosphere-ionosphere-atmosphere interaction

The aim of this study is to investigate the magnetospheric disturbances effects on complicated nonlinear system of atmospheric processes. During substorms and storms, the ionosphere was subjected to rather a significant Joule heating, and the power of precipitating energetic particles was also great. Nevertheless, there were no abnormal variations of meteoparameters in the lower atmosphere. If there is a mechanism for the powerful magnetospheric disturbance effect on meteorological processes in the atmosphere, it supposes a more complicated series of many intermediates, and is not associated directly with the energy that arrives into the ionosphere during storms. I discuss the problem of the effect of the solar wind electric field sharp increase via the global electric circuit during magnetospheric disturbances on the cloud layer formation.

physics.ao-ph↗

arXiv2004

An Alternative Approach to Explaining Magnetospheric Processes

This paper gives a brief outline of the progression from the first substorm model developed in [Ponomarev, 1985; Sedykh, Ponomarev, 2002] based on C.F. Kennel's ideas, to the present views about the mechanism by which solar wind kinetic energy is converted to electromagnetic energy at the Bow Shock and by which this energy is transferred to the magnetosphere in the form of current; about the transformation of the energy of this current to gas kinetic energy of convecting plasma tubes, and, finally, the back transformation of gas kinetic energy to electromagnetic energy in secondary magnetospheric MHD generators. The questions of the formation of the magnetospheric convection system, the nature of substorm break-up, and of the matching of currents in the magnetosphere-ionosphere system are discussed.

physics.space-ph↗

arXiv2003

Concerning the conjugation of field-aligned currents

It is known that the combined action of convection and pitch-angle diffusion is responsible for the formation of gas pressure distribution in the magnetosphere. Plasma pressure, in turn, determines - within the framework of a given magnetic field model - the density of bulk currents in the magnetosphere. With a knowledge of the bulk currents as a function of coordinates, we can calculate the field-aligned currents as a divergence of bulk currents. On the other hand, specifying the convection model is equivalent to specifying the electric field model. Since within the approximation of equipotential field lines the electric field is common to the magnetosphere and ionosphere, bulk currents and field-aligned currents in the ionosphere can be formally calculated subject to the condition that ionospheric conductivity is wholly determined by electron precipitation from the magnetosphere. The precipitation intensity is readily inferred from the same magnetospheric model. Thus we have two systems of field-aligned currents. One system is calculated from the model of plasma pressure distribution in the magnetosphere, and the other is inferred from a given model of the electric field and the electroconductivity model calculated from electron precipitation. This brings up the question: How can these two systems of field-aligned currents be reconciled? From previous studies it is known that magnetospheric convection "adjusts itself" to the level of energy losses in the ionosphere. Based on this, an attempt can be made to achieve a conjugation of the aforementioned two systems of field-aligned currents. This paper is devoted to analyzing such an attempt.

physics.geo-ph↗

arXiv2003

Conditions of excitation of magnetospheric convection by the electric current generated in the bow shock

This paper analyzes the consequences of electric current generation at the front of the Bow Shock (BS) and the dependence of the direction of this current on the IMF. The conditions of this current closure through the body of the magnetosphere are discussed. It is shown that the process of penetration of the external current into magnetized plasma has a two-stage character. Initially, a change in current on the boundary gives rise to a region of surface charge, the field of which polarizes the near-wall layer with the thickness on the order of one gyroradius of protons. The polarization process involves the formation of the displacement current which produces the Ampere force accelerating the plasma inside the double layer. When the plasma velocity reaches the electric drift velocity (within a time on the order of the inverse gyrofrequency of protons), the electric field in this plasma disappears, whereas in a fixed frame of reference, on the contrary, it reaches equilibrium values. The front of variation of the electric field penetrates the plasma with the velocity of a fast magnetosonic wave. A change in the convection velocity field causes a redistribution of plasma pressure. The appearance of corresponding gradients signifies the penetration of current into plasma. The gradients are changing until a new steady state is reached, to which the new convection velocity field and the new plasma pressure field correspond. This new state is reached in a time which is estimated.

physics.geo-ph↗

arXiv2001

Magnetosphere-Ionosphere Coupling in the Region of Auroral Electrojets

We discuss the question as to how the magnetospheric energy source feeds the ionospheric current system. It is shown that a consistent application and further development of Kennel's ideas makes it possible to successfully solve the magnetosphere-ionosphere coupling problem in regard to the formation of auroral electrojets by steady volume currents generated in the magnetosphere by the magnetospheric MHD generator in the case of a simple model which, nevertheless, retains the essential features of the reality. It is concluded that the whole of the complicated magnetospheric ''design'' only acts to redistribute, in space and time, currents and energy fluxes which must be supplied by external sources to feed the dissipative processes in the ionosphere.

physics.geo-ph↗