共查询到20条相似文献，搜索用时 46 毫秒
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Using results of numerical modeling, the dynamics of escape of electrons, produced as a result beta-decay, to the external magnetic field from a spherical plasma volume with an expelled magnetic field is studied. The dependence of the fraction of escaped electrons on time and radius of the plasma volume has been obtained for two kinds of electron sources: a point isotropic source, located at the center of the sphere, and a volume isotropic source. It is shown that for a point source some part of electrons remains in the sphere, whereas for a volume source all electrons, at different values of the magnetic cavern radius, leave it at an identical relative escape rate. 相似文献
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Charged particle motion in magnetoactive plasma with an axially symmetric electrostatic field has been studied. It has been indicated that a difference between drift velocities of electrons and ions leads to a magnetic field disturbance. The equations for stationary magnetic field disturbances stretched along the magnetic field, which can be magnetic ducts for propagation of whistlers, have been obtained. The possibility of formation of such ducts by electrostatic fields from thunderstorm sources, penetrating into the ionosphere, has been estimated. 相似文献
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Based on single-particle approximation, the peculiarities of electron acceleration by the sub-Dreicer electric field in solar atmosphere have been considered. The elastic and inelastic collisions of fast electrons with hydrogen atoms have been taken into account within the Born approximation. The rate of energy gain by accelerated electrons is inversely proportional to the mean free path of the thermal particles. Electron acceleration can be more effective in the transition region and chromosphere than in the corona. Chromospheric electrons can achieve several hundred keV energy at distances of a few tens of kilometers. 相似文献
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A. E. Levitin L. A. Dremukhina L. I. Gromova N. G. Ptitsyna 《Geomagnetism and Aeronomy》2014,54(3):300-307
The model calculation of a magnetic disturbance, which was registered at Colaba observatory (India) during the historic giant magnetic storm on September 1–2, 1859, is illustrated. The calculation demonstrates that the observed, unusually fast, 2-h main phase of this storm, when the negative amplitude of the geomagnetic field vector H component was ?1600 nT, and an extremely fast (1.5-h) initial field recovery phase from the maximum to the ?110 nT amplitude can be generated. The following models of the magnetospheric current systems were used in the calculations: the ring current (DR), the magnetospheric magnetopause current (DCF), the magnetotail current system (DT), and the high-latitude current system (DP). The unusual time variation in the registered geomagnetic disturbance is related to the probable fast and considerable equatorward shift of the high-latitude currents during the main phase of the analyzed giant storm and to the same fast backward motion of these currents during the initial field recovery phase. The unusually large amplitude of the registered geomagnetic disturbance could have been caused by the total contribution of the indicated magnetospheric current systems during the time when the storm was generated as a result of the interaction between the magnetosphere and the solar plasma ejected during the gigantic solar flare before the storm. 相似文献
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本文利用了小扰动方法、轨道法以及粒子的运动区域,比较系统地研究了带电粒子在中性线磁场中的运动。其结果是: 1.带电粒子的运动轨道可分为漂移轨道、波动轨道与8字形轨道三种形式。小扰动方法不能使用于中性线的区域内,在这个区域出现一个与小扰动漂移运动相反方向的运动。 2.在沿中性线方向的电场的作用下,中性线周围的部分粒子可以聚集到中性线附近。当粒子进入非小扰动区时,它们将被中性线磁场反射,并被电场加速。 3.计算出磁尾中性片的厚度为在这个区域内,大部分带正电的粒子的平均运动是沿晨昏方向,带负电的粒子的运动则相反。磁尾区出现一个等离子体中性片电流。 相似文献
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运用双流体MHD方程描述电子和离子的行为, 采用非扰动理论, 把孤子看作经典粒子, 通过推导的赝势(也称Sagdeev势)方程, 结合数值计算来研究惯性区低-β等离子体中动力学Alfvén孤波的特性. 结果表明离子热效应对Alfvén孤波特性的影响不可忽略, 且在惯性区稀疏型孤波和压缩型孤波均存在. 此结论与Freja卫星在极区上空所观测结果吻合很好. Alfvén孤波携带有平行电场, 它对带电粒子的加速有重要作用, 这给极光粒子加速提供了一种可能的物理机制. 相似文献
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The dynamics of the distribution of nonthermal electrons, injected into a collapsing magnetic trap, has been considered. The electron energy and pitch angle nonstationary spatial distributions in an extensive magnetic trap have been obtained for the first time for different laws of inhomogeneous magnetic field evolution in this trap by numerically solving the Fokker-Planck kinetic equation. The gyrosynchrotron emission intensity has been calculated for the obtained electron spatial distributions. It has been indicated that energetic electrons are effectively accumulated and accelerated at the top of a collapsing trap due to the first-order Fermi and betatron acceleration mechanisms at certain rates of variations in the magnetic field and background plasma density. 相似文献
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《Journal of Atmospheric and Solar》2000,62(6):521-526
Cold dense plasma with the ionospheric origin is often observed in the outer magnetosphere with L values as large as 10. We have examined the electric field data accompanied by the cold dense plasma. The electric field data are obtained by the direct measurement of the drift motion of electrons released from electron guns. We get westward components of convection. In addition, there is an AC component of electric field in the ULF range larger than the DC component. If such a large variation of electric field exists in the vicinity of the stagnation point, the plasmaspheric plasma is expected to flow away to the outer magnetosphere. Then we have a test particle simulation by adding a potential variable in time. There is a particle outflow accompanied by the AC variation of electric field in the ULF range. If there are more complicated variations of electric field, it is possible that particles flow out frequently. 相似文献
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We study the possibility of electrostatic blanking of beta electrons in the expanding spherical blob of a radioactive plasma
in a rarefied ionosphere. From numerical studies on the dynamics of beta electrons departing a cavern, we obtain the form
of a function that determines the portion of departing electrons and calculate the flux density of beta electrons inside the
cavern in relation to the Starfish Prime nuclear blast. We show that the flux density of electrons in geomagnetic flux tubes
and inside the cavern depend on a correct allowance for the quantity of beta electrons returning to the cavern. On the basis
of a physical analysis, we determine the approximate criterion for the return of electrons from a geomagnetic flux tube to
the cavern. We compare calculation results in terms of the flux density of beta electrons inside the cavern with the recently
published experimental results from operation Starfish Prime. 相似文献
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《Journal of Atmospheric and Solar》2007,69(9):969-972
The relativistic motion of electrons in the field of a finite amplitude circularly polarized whistler propagating along a constant magnetic field in a plasma with longitudinal inhomogeneity is considered. It is shown that the equations of the particle motion exhibit a constant of the motion despite the spatial dependence of the wave parameters. The existence of the constant allows one to reduce the equations of motion to a canonical form describing one-dimensional oscillations of a particle with the Hamiltonian slowly varying in the process of the oscillations. 相似文献
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O. V. Mingalev I. V. Mingalev V. S. Mingalev M. L. Khodachenko 《Geomagnetism and Aeronomy》2009,49(5):574-581
The problem of a smooth field configuration, which should be an initial configuration in modeling (using the method of coarse particles) the problem of a stationary solar wind flow around a magnetic cloud in the case of a spatially two-dimensional statement (when a magnetic cloud is considered as a force-free magnetic cylinder with a finite radius) is considered. It has been indicated that such a statement is possible only when the magnetic field in the solar wind is parallel to the cylinder axis. The method for finding the magnetic field of a force-free cylinder with a finite radius, when some field component is specified and another component is determined based on this one (which makes it possible to construct fields with preassigned properties), has been proposed. The variant for constructing the initial field configuration in the transition region around a cylinder has been proposed. This variant makes it possible to gradually pass from homogeneous crossed fields in the solar wind to a force-free magnetic and zero electric fields within a cylinder, an electric field being potential and orthogonal to a magnetic field (in the reference system related to a magnetic cloud). 相似文献
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The generation of electromagnetic oscillations in the vicinity of the lower hybrid resonance and at the frequency of bounce oscillations of fast electrons in the plasma resonator of the magnetospheric type, formed by an HF discharge in a mirror magnetic trap, has been detected and studied. The results of the field rocket experiments aimed at stimulating maser effects, including such effects at frequencies of bounce oscillations of 40-keV electrons in the magnetospheric flux tube of the geomagnetic field, are discussed. 相似文献
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A kinetic theory is necessary to explain the electron flows forming strong field-aligned currents in the auroral region. Its construction in this paper is based on the following propositions. (a) In the equatorial region, the arrival of electrons through the lateral surface of the magnetic flux tube is compensated for by their escape along the magnetic field. This is provided by action of the pitch-angle diffusion mechanism in the presence of plasma turbulence concentrated in this region. (b) Outside the equatorial region, the distribution functions of trapped and precipitating particles become “frozen.” The distributions and particle concentrations are calculated there in a model with conservation of the total energy and the magnetic moment. (c) The quasi-neutrality condition yields a large-scale parallel electric field, which contributes to the conserved total energy. In this field, the electron acceleration occurs, causing strong field-aligned currents directed upward from the ionosphere. 相似文献
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The influence of whistlers on the distribution and gyrosynchrotron radiation of fast electrons injected into a coronal magnetic trap is considered. The kinetic equation in the Fokker–Planck approximation with consideration of fast electron scattering, both on background plasma particles and on whistlers, is solved for an inhomogeneous trap. It is supposed that the source of whistlers is a nonstationary process of flare energy release. Having found the fast electron distribution, we can calculate their gyrosynchrotron microwave emission. The influence of nonthermal electron scattering on whistlers are compared with the effects of scattering on Coulomb collisions. It is shown that whistlers considerably modify the emission characteristics of a loop at a certain energy density; in particular, they steepen the frequency spectrum. This is useful for microwave diagnostics of plasma turbulence in the flare loop. 相似文献
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G. N. Kichigin L. I. Miroshnichenko V. I. Sidorov S. A. Yazev 《Geomagnetism and Aeronomy》2016,56(4):393-400
The analysis of observations of large solar flares made it possible to propose a hypothesis on existence of a skin-layer in magnetic flux ropes of coronal mass ejections. On the assumption that the Bohm coefficient determines the diffusion of magnetic field, an estimate of the skin-layer thickness of ~106 cm is obtained. According to the hypothesis, the electric field of ~0.01–0.1 V/cm, having the nonzero component along the magnetic field of flux rope, arises for ~5 min in the surface layer of the eruptive flux rope during its ejection into the upper corona. The particle acceleration by the electric field to the energies of ~100 MeV/nucleon in the skin-layer of the flux rope leads to their precipitation along field lines to footpoints of the flux rope. The skin-layer presence induces helical or oval chromospheric emission at the ends of flare ribbons. The emission may be accompanied by hard X-ray radiation and by the production of gamma-ray line at the energy of 2.223 MeV (neutron capture line in the photosphere). The magnetic reconnection in the corona leads to a shift of the skin-layer of flux rope across the magnetic field. The area of precipitation of accelerated particles at the flux-rope footpoints expands in this case from the inside outward. This effect is traced in the chromosphere and in the transient region as the expanding helical emission structures. If the emission extends to the spot, a certain fraction of accelerated particles may be reflected from the magnetic barrier (in the magnetic field of the spot). In the case of exit into the interplanetary space, these particles may be recorded in the Earth’s orbit as solar proton events. 相似文献