Measurement of the transpolar potential in laboratory magnetosphere

Results of measurements of the transpolar potential in a laboratory magnetosphere are presented. Its approximately linear dependence on the kinetic energy of ions of the incoming flow is found. The measurements of the electric potential in plasma have shown the presence of an asymmetry along the dawn-dusk line. Near the boundary layer at the dawn side, the potential is systematically higher than the average values, while at the dusk side it is systematically lower. The observed difference in the plasma potential in the lowlatitude equatorial part of the magnetosphere by its sign and magnitude approximately corresponds to the transpolar potential at the poles of a dipole. The obtained laboratory data give a direct confirmation of the magnetospheric generator model.     

Energetic electrons in the tail and transition region of the magnetosphere

A comparative analysis has been carried out of the parameters of energetic electrons in the tail of the Earth’s magnetosphere that belong to three sources, i.e., electrons of solar origin, electrons generated in the magnetosphere of Jupiter, and electrons in the Earth’s magnetosphere. The differences in the time profiles of fluxes and energy spectra of the three electron sources, their relation to fluxes outside the magnetosphere, and periods of the occurrence of electron fluxes of each type are considered.     

A Magnetospheric Substorm and the Motion of the Magnetopause

Using a single event as an example, we make an analysis of the time development of a substorm and estimate its influence on the motion of the low-latitude boundary of the magnetosphere. To this end, we compare the data on plasma and magnetic field obtained by five spacecraft (WIND, INTERBALL-1, GEOTAIL, GOES-8, and GOES-9) with measurements made by ground-based stations. It is shown that the release of energy of the geomagnetic tail begins from a disruption of the current sheet near the Earth. The high-speed plasma stream that transfers a magnetic flux to the Earth and can have an effect on the magnetic field configuration near the Earth is detected later. Almost simultaneously with a substorm onset a series of magnetopause crossings has been detected by the INTERBALL-1 satellite on the evening side of the low-latitude magnetosphere. In this paper we consider some of possible causes of this motion of the magnetosphere boundary, including variations of parameters of the solar wind, Kelvin-Helmholtz instability, and substorm processes. It is shown that fast motions of the magnetopause are detected almost simultaneously with field variations in the near magnetotail of the Earth and geomagnetic pulsations Pi2 on ground-based stations. A sufficiently high degree of correlation (K = 0.67) between the amplitude of Pi2 pulsations and the amplitude of magnetic field variations near the magnetopause is probably indicative of the connection of short-term motions of the magnetosphere boundary with the tail current disruption and the process of formation of a substorm current wedge.__________Translated from Kosmicheskie Issledovaniya, Vol. 43, No. 4, 2005, pp. 248–259.Original Russian Text Copyright © 2005 by Nikolaeva, Parkhomov, Borodkova, Klimov, Nozdrachev, Romanov, Yermolaev.     

Penetration of solar cosmic rays into the Earth’s magnetosphere on January 28, 2012

Results of the comparative analysis of the dynamics of SCR fluxes with energies of 1–100 MeV in the interplanetary environment according to the data of the ACE and Wind spacecraft and within the Earth’s magnetosphere according to the data of the GOES-15 and Electro-L satellites in the region of geostationary orbits, and POES-19 and Meteor-M1 in the region of polar caps during two increases in SCR of January 19–31, 2012, are presented. It is shown that the decrease in the efficiency of SCR penetration into the Earth’s magnetosphere in the region of the orbits under study on January 28, 2012, is related to the passage of the Earth’s magnetosphere through the interplanetary environment structure with a quasi-radial interplanetary magnetic field and a small pressure of the solar wind.     

Acceleration and particle transport in collisionless plasma in the process of dipolarization and nonstationary turbulence

This work is devoted to studying the processes of the acceleration of plasma particles in thin current sheets that appear during magnetospheric substorms in the Earth’s magnetosphere tail. A numerical model of magnetic dipolarization accompanied by plasma turbulence has been constructed and studied. The model allows one to investigate the particle acceleration due to the action of three principal mechanisms: (1) plasma turbulence; (2) magnetic dipolarization; (3) their simultaneous action. For the given velocity kappa-distributions, we obtained energy spectra of three types of accelerated particles, i.e., protons p⁺, ions of oxygen O⁺, and electrons e^–. It has been shown that the combined mechanism of dipolarization with turbulence (3) makes the largest contribution to the increase in the energy of protons and heavy ions as compared with a separate action of each of mechanisms (1) and (2); in this case, electrons accelerate less. The consideration of the joint action of acceleration mechanisms (1) and (2) can explain the apparition of particles with energies on the order of magnitude equal to hundreds keV in the Earth’s magnetosphere tail.     

Calculation of the Initial Magnetic Field for Mercury’s Magnetosphere Hybrid Model

Several types of numerical models are used to analyze the interactions of the solar wind flow with Mercury’s magnetosphere, including kinetic models that determine magnetic and electric fields based on the spatial distribution of charges and currents, magnetohydrodynamic models that describe plasma as a conductive liquid, and hybrid models that describe ions kinetically in collisionless mode and represent electrons as a massless neutralizing liquid. The structure of resulting solutions is determined not only by the chosen set of equations that govern the behavior of plasma, but also by the initial and boundary conditions; i.e., their effects are not limited to the amount of computational work required to achieve a quasi-stationary solution. In this work, we have proposed using the magnetic field computed by the paraboloid model of Mercury’s magnetosphere as the initial condition for subsequent hybrid modeling. The results of the model have been compared to measurements performed by the Messenger spacecraft during a single crossing of the magnetosheath and the magnetosphere. The selected orbit lies in the terminator plane, which allows us to observe two crossings of the bow shock and the magnetopause. In our calculations, we have defined the initial parameters of the global magnetospheric current systems in a way that allows us to minimize paraboloid magnetic field deviation along the trajectory of the Messenger from the experimental data. We have shown that the optimal initial field parameters include setting the penetration of a partial interplanetary magnetic field into the magnetosphere with a penetration coefficient of 0.2.     

Empirical model of the high-latitude boundary of the Earth’s outer radiation belt at altitudes of up to 1000 km

An empirical model of the high-latitude boundary of the outer Earth’s radiation belt (ERB) has been presented, which is based on the measurement data of electron fluxes on the polar low-orbit CORONAS-Photon, Meteor-M1, and Meteor-M2 satellites. The boundary was determined by a sharp decrease to the background level of the flux of trapped electrons with energies of 100 or 200 keV in the polar part of the profile of the outer radiation belt. A numerical algorithm has been implemented to determine the time moment, when the fastest flux changes are recorded. The primary search was carried out, first, on 30 s averaged data, then repeated on data with a higher resolution. A functional dependence was obtained in order to approximate the obtained set of intersections of the boundary by elliptical curve. The empirical model constructed using the CORONAS-Photon measurement data in the epoch of anomalously low geomagnetic activity reflects the longitude structure of the high-latitude boundary of the outer radiation belt associated with the internal Earth’s magnetic field (MF), as well as its dependence on the universal time. Based on the data of intersections of the high-latitude boundary of the outer ERB (OERB) in the epoch of 2014–2016, the latitudinal shift of the boundary to the equator dependent on geomagnetic activity has been determined, as well as the nightside shift of the boundary due to the diurnal rotation of the Earth.     

Features of whistling electromagnetic wave propagation descending from above upon the night ionosphere

The results of numerical solution of the wave equations for the oblique incidence of whistling electromagnetic waves upon the night ionosphere from above have been obtained and analyzed. In the studied region of altitudes, within the wavelength scale, charged particle concentration varies drastically, and damping caused by collisions between the charged and neutral particles decreases considerably. Below, the sharp lower boundary of the ionosphere, the refractive index of the whistler wave approaches unity, and plasma turbulence transform into atmospheric electromagnetic waves. The dependences of the whistler reflection factor are found in terms of energy and horizontal magnetic component of the electromagnetic wave near the Earth’s surface on the frequency and the wave vector transverse component for the plain-layered medium model at two values of latitude. Strong dependences have been found on the wave angle of incidence and frequency. At rather small angles of incidence, the wave disturbances reach the Earth’s surface, and the module of reflection coefficient logarithm is in the range of 0.4–1. At large angles of incidence, the reflection coefficient module varies over a wide range depending on specific conditions. The obtained results explain the absence of oscillation modes of plasma magnetosphere maser in the night magnetosphere.     

Turbulent fluctuations of plasma and magnetic field parameters in the magnetosheath and the low-latitude boundary layer formation: Multisatellite observations on March 2, 1996

The results of simultaneous analysis of plasma and magnetic field characteristics measured on the INTERBALL/Tail Probe, WIND and Geotail satellites on March 2, 1996, are presented. During these observations the INTERBALL/Tail Probe crossed the low-latitude boundary layer, and the WIND and Geotail satellites measured the solar wind’s and magnetosheath’s parameters, respectively. The plasma and magnetic field characteristics in these regions have been compared. The data of the Corall, Electron, and MIF instruments on the INTERBALL/Tail Probe satellite are analyzed. Fluctuations of the magnetic field components and plasma velocity in the solar wind and magnetosheath, measured onboard the WIND and Geotail satellites, are compared. The causes resulting in appearance of plasma jet flows in the low-latitude boundary layer are analyzed. The amplitude of magnetic field fluctuations in the magnetosheath for a studied magnetosphere boundary crossing is shown to exceed the magnetic field value below the magnetopause near the cusp. The possibility of local violation of pressure balance on the magnetopause is discussed, as well as penetration of magnetosheath plasma into the magnetosphere, as a result of magnetic field and plasma flux fluctuations in the magnetosheath.     

基于粒子云方法研究地磁场对运动电子束的时空分布影响

空间电荷效应是空间带电粒子分布直接产生的相关效应,对于理解空间辐射环境有着重要意义.为研究地球磁场对空间电荷效应的影响,文章通过数值求解Poisson方程和相对论粒子运动方程,建立粒子云(particle-in-cell,PIC)自洽模型,并构建地球偶极子磁场模型作为内磁层背景磁场(空间分布L值为3～7).在模型基础上...     

RATAN-600 microwave observations of powerful active regions from October 23 to November 5, 2003

Application of the mode of azimuthal observations on RATAN-600 has made it possible to realize multiple daily observations [1]. The results of multiwavelength observations of the Sun in this mode point to the existence of sharp spectral irregularities in the polarized radiation of flare-productive active regions (FPARs) producing especially powerful flares [2]. These phenomena occur in a broad range of radio-emission fluxes (0.05–200 s.f.u.), in a rather narrow wavelength band (2–5 cm), and they are recorded during the time interval from several hours to several days before a powerful flare, as well as during the flare. Frequently, such events indicate an eruption of powerful coronal mass ejections and high-energy particle (proton) fluxes, which, when reaching the Earth’s magnetosphere, trigger its disturbances. Here, we analyze events in the microwave band connected with the strongest flares which took place on October 28 and November 4, 2003.     

The effect of heavy ions on the spectrum of oscillations of the magnetosphere

Some issues concerning the influence of multi-ion composition of plasma on the spectrum of ultralow frequency (ULF) oscillations in the magnetosphere are analyzed. Main emphasis is made on the effects that are perceptible by analyzing the results of observations of ULF oscillations. The resonator confining ion cyclotron waves in the equatorial zone high above the Earth is considered, as well as the near-equatorial waveguide existing under the plasmasphere arch and canalizing magnetosonic waves in the azimuth direction. It is shown that the very existence of the ion-cyclotron resonator would be impossible, if only one species of ions were contained in plasma. It is emphasized that the problem of excitation of magnetosonic waves with harmonics of the gyrofrequency of O⁺ needs further investigation. The effect of heavy ions on the spectrum of Alfvén oscillations of the magnetosphere is considered. Some arguments are presented giving evidence that existence of alpha-particles in the solar wind leads to an asymmetry of the spectrum of magnetosonic oscillations in front of the Earth’s bow shock. Anomalously large asymmetry is expected at immersion of the Earth into the “plasmasphere” of the flare-associated stream of solar plasma. The general conclusion is made that even a small admixture of heavy ions can have a substantial effect on the spectrum of ULF oscillations.     

On the dynamics of latitudinal profiles of low-energy solar protons in the Earth magnetosphere

Many works have been devoted to studying the boundaries of the penetration of solar protons into the Earth’s magnetosphere. This work first considers the dynamics of not only the boundary, but the latitudinal profiles of penetration in general depending on the energy and local time of measurement according to the data of the low-altitude CORONAS-F satellite. When flying through the polar cap, the isotropic pitchangle distribution of protons leads to the equality of the recorded precipitating flux and the proton flux in the interplanetary space. Beginning at a particular latitude, the proton flux begins to drop and, over time, reaches the level of the background of galactic cosmic rays. The latitudinal profile measured in this manner on the night side reaches the bending point when the Larmor radius of the proton becomes comparable with the radius of the curvature of the line of force; after partial trapping, the flux of precipitating protons successively drops. The protons are transferred to the day side by the magnetic drift and, unlike the night profile, the character of the day profile depends on the configuration of the entire magnetosphere. The character of latitudinal profiles has been studied depending on the local time and energy of the particles, which enabled the features of the magnetosphere deformation to be evaluated at certain times of magnetic storms.     

Physical Simulation of a Prolonged Plasma-Plume Exposure of a Space Debris Object

A methodology has been developed for the physical (laboratory) simulation of the prolonged exposure of a space debris object to high-energy ions of a plasma plume for removing the object into low-Earth orbit with its subsequent burning in the Earth’s atmosphere. The methodology is based on the equivalence criteria of two modes of exposure (in the Earth’s ionosphere and in the setup) and the procedure for accelerated resource tests in terms of the sputtering of the space debris material and its deceleration by a plasma jet in the Earth’s ionosphere.     

Dynamics of debye-scale nonstationary plasma structures in the region of auroral field-aligned currents

We consider the formation of small-scale nonstationary plasma structures in the region of relatively strong field-aligned electric currents. The formation of these structures has been shown to be associated with the density instability developed when the current velocity exceeds a critical value. The conditions for the development of this instability can be most favorable in the region of low-density plasma. Numerical calculations have been performed for the initial nonlinear stage of the structure development. The main parameters of the structure, i.e., the times of its formation and destruction, spatial scales, and electric field, have been estimated. The features of the structures are consistent with the existing data from space experiments in the region of auroral field-aligned currents of the Earth.     

Verification of the Accuracy of the Magnetopause Empirical Models Using the INTERBALL-1 Satellite Data

A statistical analysis of the shape and location of the magnetopause according to the INTERBALL-1 satellite data for the period 1995–1997 is carried out. The instants of crossing the magnetosphere boundaries obtained by the plasma and magnetic data are compared with computations based on three empirical models, namely, Petrinec and Russel, 1996; Shue et al., 1997; and Shue et al., 1998. The state of the interplanetary medium (dynamic pressure of the solar wind plasma P _d and the B _z component of the interplanetary magnetic field) was determined by the measurements onboard the WIND spacecraft. We estimate the accuracy of the considered models for different groups of boundary crossings: single, multiple with small duration (less than 40 min), and multiple with large duration (more than 40 min). It is demonstrated that the small-scale motions of the boundary (<1R _E) are observed more often in the dayside magnetosphere, especially near the cusp region. Large-scale boundary oscillations (>1R _E) are more common in the tail region of the magnetosphere, namely, its flanks. Various models give similar results: about 50% of all events have deviations by more than 1R _E from the model locations. In some cases, the deviation of the measured location of the magnetosphere boundary from the model prediction may be as large as 5–6R _E for all three models considered, the actual boundary being more often located nearer to the Earth than the result of model computations. The best model is that of Shue et al., 1998, but it does not differ significantly from the other models.     

One method of gravitational attitude control of a rotating satellite

The mode of spinning up a low-orbit satellite in the plane of its orbit is studied. In this mode, the satellite rotates around its longitudinal axis (principal central axis of the minimum moment of inertia), which executes small oscillations with respect to the normal to the orbit plane; the angular velocity of the rotation around the longitudinal axis is several tenths of a degree per second. Gravitational and restoring aerodynamic moments were taken into account in the equations of satellite’s motion, as well as a dissipative moment from eddy currents induced in the shell of the satellite by the Earth’s magnetic field. A small parameter characterizing deviation of the satellite from a dynamically symmetric shape and nongravitational external moments are introduced into the equations. A two-dimensional integral surface of the equations of motion, describing quasistationary rotations of the satellite close to cylindrical precession of the corresponding symmetrical satellite in a gravitational field, has been studied by the method of small parameter and numerically. We propose to consider such quasistationary rotations as unperturbed motions of the satellite in the spin-up mode.     

Space charge sheath formation in a magnetized plasma flow around space bodies

Space charge sheath formation in a magnetized plasma flow around space bodies is considered for the cases of high surface conductivity, free electron emission, dipole magnetic field. The results are applied to explain different phenomena in the ionosphere and magnetosphere of the Earth and planets such as polar aurora and kilometric radiation of the Earth and decametric radiation of the Jovian satellite Io.     

Electromagnetic Pulse in the Magnetosphere Generated by Impulsive Current near the Lower Boundary of the Ionosphere

A solution to the problem of current spreading is constructed in the case of relaxation of electric charges, which have arisen in the mesosphere for one reason or other. These currents penetrate into the conductive region with anisotropic conductivity of the D- and E-layers of the ionosphere, being transformed to a MHD-wave that propagates into the magnetosphere. Based on this solution, the form and spectrum of the generated MHD signal are calculated for Alfvenic and magnetosonic modes coming out to the ionosphere and magnetosphere. Electric charges and currents can arise, for example, in the space between a thunderstorm cloud and the ionosphere, or between the shock wave from a ground explosion and the ionosphere. Some signal parameters accepted in the model are close to those expected for high-altitude electric discharges of the Red Sprite type. The conditions are determined under which the Alfven impulse with an amplitude of up to 100 nT propagates in the magnetosphere above high-altitude discharge of this type. Such an impulse was recorded by the AUREOL-3 satellite after the ground explosion MASSA-1. Recently, this impulse was hypothesized to originate as a result of a high-altitude electric discharge. The hypothesis on a similar MHD pulse allows one to explain in a semiquantitative way the short burst of electron field-aligned acceleration observed by the DE-2 satellite over the Debbie hurricane. The high-altitude atmospheric discharge of this type can be a powerful, though short-time and local, source of electrons with kiloelectronvolt energies at low and middle latitudes. One could expect that such an effect causes a modified character of the so-called Trimpi-effect (a short-term disturbance of propagation of VLF waves in the ionosphere), and thus, it can be observable.     

Situation studies of aes orbits for solar-Earth space experiments

The questions on the orbit selection for studying various areas of the Earth magnetosphere are discussed. The method of the orbit selection is based on the use of orbital tori and on the construction of areas of orbit set intersection with model surfaces, forming specific areas in the near Earth space: bow shock (BSh), magnetopause (MP) neutral sheet in the magnetosphere tail, cusp etc. Intersections of the “Prognoz” 1–8 orbit set with model surfaces BSh and MP are shown.