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1.
The point source of neutral gas undergoing ionization and expanding into an uniform magnetic field is considered. Friction
between the neutral and ionized particles results in the formation of the magnetic field barrier and diamagnetic cavity surrounding
the source. At least one neutral point inevitably arises at the boundary of the cavity. When the neutral gas production rate
grows, two neutral points may arise at this boundary. In the vicinity of these points magnetic field lines converge, along
with the plasma flow which is magnetic field aligned in the steady state. As a result, two plasma jets originate from the
neutral points. Possible relation of these jets to cometary rays is discussed.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
2.
The estimates of the magnetic field in the Halley's comet tail based on the observed acceleration of the matter and the pressure balance are discussed. 相似文献
3.
I. M. Podgorny E. M. Dubinin P. L. Israelevich C. P. Sonett 《Earth, Moon, and Planets》1982,27(4):397-406
Analysis of Venera 9 and 10 data suggest a comingled excitation of the ionosphere of Venus by the time dependent component of the interplanetary magnetic field, upon which may be super-imposed a contribution from the interplanetary electric field. The inductive contributions correspond respectively to generation of eddy currents and to unipolar induction, i.e., the TE and TM modes of classical electromagnetism. The former is suggested when the interplanetary magnetic field exhibits significant changes in intensity or orientation, but could also have contributions from fluctuations in plasma pressure expressed through the frozen-in field. Since the TM mode depends upon E=v
c
×B, the TM mode can also have an unsteady component. The magnetic field measured near Venus by Venera 9 and 10 is considered within this framework and with respect to laboratory simulation using both conducting and insulated (but internally conducting) spheres. 相似文献
4.
E.M. Dubinin P.L. Israelevich N.S. Nikolaeva I. Kutiev I.M. Podgorny 《Planetary and Space Science》1985,33(6):597-606
An intense, localized auroral disturbance observed by Intercosmos-Bulgaria-1300 satellite in the morning sector at the altitude 850 km is analyzed in detail. The disturbance is characterized by strong “jumps” of electric and magnetic fields reaching ～ 80 mV/m and ～ 100 nT, fluctuations of ion density (Δn/n ～ 70%) and bursts of downward and upward energetic electron fluxes. Electric and magnetic disturbances display a distinct spatial-temporal relationship typical for the standing quasi-monochromatic wave (). The ratio of amplitudes of electric and magnetic fluctuations is equal to Alfvén velocity (ΔE/ΔB ～ vA/c). However, a strong parallel component of the electric field (～ 30 mV/m) and large ion density fluctuations indicate significant changes of plasma properties (the effects of anomalous resistivity are possible). 相似文献
5.
Parameters of the plasma in the inner coma of comet Halley are derived from the magnetic field measurements by using single particle approximation. Both the plasma velocity and the temperature obtained by using this approach are self-consistent and happen to be in good agreement within situ measurements whereas the neutral gas production rate happens to be 2–3 times higher than the conventionally cited value 6.9 × 1029 s–1. 相似文献
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The model problem simulating a vortex development is solved numerically. Breakdown of the velocity sheared layer due to the nonlinear evolution of the Kelvin-Helmholtz instability is shown to lead to the wave crest overturning and, eventually, to formation of a large-scale vortex. The magnetic field strength in the vortex core turns out to be lower than that in the ambient plasma, so that vortex core may be called the magnetic channel.The mechanism of the magnetic field generation by a single vortex is studied analytically within the framework of magnetokinematics. It appeared that there is no magnetic field generation in the vortex core where rotation of the plasma is rigid. Therefore, the magnetic field here is reduced, and hence the plasma density is enhanced.These results seem to support the hypothesis of the comet ray origin as magnetically channeled outflow: the magnetic channel might become visible as a comet ray against adjacent plasma of lesser density outside the magnetic channel. 相似文献
9.
The comparison of data obtained in laboratory experiments on the solar wind interaction with a body endowed with a plasma shell, the observations of comet type I tails and the direct measurements near Venus show that an induced magnetosphere is formed with an extended magnetic tail. This magnetosphere appears due to currents associated with unipolar induction. The distribution of electrodynamical forces associated with the formation of the induced magnetosphere makes it possible to explain the acceleration of matter towards the tail as in the motion across the tail observed in comets and Venus. The analysis of the condensation motion in Halley's comet yields an estimate of tail magnetic field of 30 to 50. A three-dimensional model of the induced magnetospheres of Venus and comets is developed. 相似文献
10.
In this study we test a stream function method suggested by Israelevich and Ershkovich for instantaneous reconstruction of global, high-latitude ionospheric convection patterns from a limited set of experimental observations, namely, from the electric field or ion drift velocity vector measurements taken along two polar satellite orbits only. These two satellite passes subdivide the polar cap into several adjacent areas. Measured electric fields or ion drifts can be considered as boundary conditions (together with the zero electric potential condition at the low-latitude boundary) for those areas, and the entire ionospheric convection pattern can be reconstructed as a solution of the boundary value problem for the stream function without any preliminary information on ionospheric conductivities. In order to validate the stream function method, we utilized the IZMIRAN electrodynamic model (IZMEM) recently calibrated by the DMSP ionospheric electrostatic potential observations. For the sake of simplicity, we took the modeled electric fields along the noon-midnight and dawn-dusk meridians as the boundary conditions. Then, the solution(s) of the boundary value problem (i.e., a reconstructed potential distribution over the entire polar region) is compared with the original IZMEM/DMSP electric potential distribution(s), as well as with the various cross cuts of the polar cap. It is found that reconstructed convection patterns are in good agreement with the original modeled patterns in both the northern and southern polar caps. The analysis is carried out for the winter and summer conditions, as well as for a number of configurations of the interplanetary magnetic field. 相似文献