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SWE,a comprehensive plasma instrument for the WIND spacecraft 总被引:1,自引:0,他引:1
K. W. Ogilvie D. J. Chornay R. J. Fritzenreiter F. Hunsaker J. Keller J. Lobell G. Miller J. D. Scudder E. C. Sittler Jr. R. B. Torbert D. Bodet G. Needell A. J. Lazarus J. T. Steinberg J. H. Tappan A. Mavretic E. Gergin 《Space Science Reviews》1995,71(1-4):55-77
The Solar Wind Experiment (SWE) on the WIND spacecraft is a comprehensive, integrated set of sensors which is designed to investigate outstanding problems in solar wind physics. It consists of two Faraday cup (FC) sensors; a vector electron and ion spectrometer (VEIS); a strahl sensor, which is especially configured to study the electron strahl close to the magnetic field direction; and an on-board calibration system. The energy/charge range of the Faraday cups is 150 V to 8 kV, and that of the VEIS is 7 V to 24.8 kV. The time resolution depends on the operational mode used, but can be of the order of a few seconds for 3-D measurements. Key parameters which broadly characterize the solar wind positive ion velocity distribution function will be made available rapidly from the GGS Central Data Handling Facility. 相似文献
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We have developed a 2D semi-empirical model (Sittler and Guhathakurta 1999) of the corona and the interplanetary medium using
the time independent MHD equations and assuming azimuthal symmetry, utilizing the SOHO, Spartan and Ulysses observations.
The model uses as inputs (1) an empirically derived global electron density distribution using LASCO, Mark III and Spartan
white light observations and in situ observations of the Ulysses spacecraft, and (2) an empirical model of the coronal magnetic
field topology using SOHO/LASCO and EIT observations. The model requires an estimate of solar wind velocity as a function
of latitude at 1 AU and the radial component of the magnetic field at 1 AU, for which we use Ulysses plasma and magnetic field
data results respectively. The model makes estimates as a function of radial distance and latitude of various fluid parameters
of the plasma such as flow velocity V, temperature Teff, and heat flux Qeff which are derived from the equations of conservation of mass, momentum and energy, respectively, in the rotating frame of
the Sun. The term "effective" indicates possible wave contributions. The model can be used as a planning tool for such missions
as Solar Probe and provide an empirical framework for theoretical models of the solar corona and solar wind.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
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Blanc M. Bolton S. Bradley J. Burton M. Cravens T.E. Dandouras I. Dougherty M.K. Festou M.C. Feynman J. Johnson R.E. Gombosi T.G. Kurth W.S. Liewer P.C. Mauk B.H. Maurice S. Mitchell D. Neubauer F.M. Richardson J.D. Shemansky D.E. Sittler E.C. Tsurutani B.T. Zarka Ph. Esposito L.W. Grün E. Gurnett D.A. Kliore A.J. Krimigis S.M. Southwood D. Waite J.H. Young D.T. 《Space Science Reviews》2002,104(1-4):253-346
Magnetospheric and plasma science studies at Saturn offer a unique opportunity to explore in-depth two types of magnetospheres.
These are an ‘induced’ magnetosphere generated by the interaction of Titan with the surrounding plasma flow and Saturn's ‘intrinsic’
magnetosphere, the magnetic cavity Saturn's planetary magnetic field creates inside the solar wind flow. These two objects
will be explored using the most advanced and diverse package of instruments for the analysis of plasmas, energetic particles
and fields ever flown to a planet. These instruments will make it possible to address and solve a series of key scientific
questions concerning the interaction of these two magnetospheres with their environment.
The flow of magnetospheric plasma around the obstacle, caused by Titan's atmosphere/ionosphere, produces an elongated cavity
and wake, which we call an ‘induced magnetosphere’. The Mach number characteristics of this interaction make it unique in
the solar system. We first describe Titan's ionosphere, which is the obstacle to the external plasma flow. We then study Titan's
induced magnetosphere, its structure, dynamics and variability, and discuss the possible existence of a small intrinsic magnetic
field of Titan.
Saturn's magnetosphere, which is dynamically and chemically coupled to all other components of Saturn's environment in addition
to Titan, is then described. We start with a summary of the morphology of magnetospheric plasma and fields. Then we discuss
what we know of the magnetospheric interactions in each region. Beginning with the innermost regions and moving outwards,
we first describe the region of the main rings and their connection to the low-latitude ionosphere. Next the icy satellites,
which develop specific magnetospheric interactions, are imbedded in a relatively dense neutral gas cloud which also overlaps
the spatial extent of the diffuse E ring. This region constitutes a very interesting case of direct and mutual coupling between
dust, neutral gas and plasma populations. Beyond about twelve Saturn radii is the outer magnetosphere, where the dynamics
is dominated by its coupling with the solar wind and a large hydrogen torus. It is a region of intense coupling between the
magnetosphere and Saturn's upper atmosphere, and the source of Saturn's auroral emissions, including the kilometric radiation.
For each of these regions we identify the key scientific questions and propose an investigation strategy to address them.
Finally, we show how the unique characteristics of the CASSINI spacecraft, instruments and mission profile make it possible
to address, and hopefully solve, many of these questions. While the CASSINI orbital tour gives access to most, if not all,
of the regions that need to be explored, the unique capabilities of the MAPS instrument suite make it possible to define an
efficient strategy in which in situ measurements and remote sensing observations complement each other.
Saturn's magnetosphere will be extensively studied from the microphysical to the global scale over the four years of the mission.
All phases present in this unique environment — extended solid surfaces, dust and gas clouds, plasma and energetic particles
— are coupled in an intricate way, very much as they are in planetary formation environments. This is one of the most interesting
aspects of Magnetospheric and Plasma Science studies at Saturn. It provides us with a unique opportunity to conduct an in situ investigation of a dynamical system that is in some ways analogous to the dusty plasma environments in which planetary systems
form.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
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Guhathakurta Madhullika Sittler Ed Fisher Richard Kucera Theresa Gibson Sarah McComas Dave Skoug Ruth 《Space Science Reviews》2001,97(1-4):45-50
The large-scale coronal magnetic fields of the Sun are believed to play an important role in organizing the coronal plasma
and channeling the high and low speed solar wind along the open magnetic field lines of the polar coronal holes and the rapidly
diverging field lines close to the current sheet regions, as has been observed by the instruments aboard the Ulysses spacecraft from March 1992 to March 1997. We have performed a study of this phenomena within the framework of a semi-empirical
model of the coronal expansion and solar wind using Spartan, SOHO, and Ulysses observations during the quiescent phase of the solar cycle. Key to this understanding is the demonstration that the white
light coronagraph data can be used to trace out the topology of the coronal magnetic field and then using the Ulysses data to fix the strength of the surface magnetic field of the Sun. As a consequence, it is possible to utilize this semi-empirical
model with remote sensing observation of the shape and density of the solar corona and in situ data of magnetic field and
mass flux to predict values of the solar wind at all latitudes through out the solar system. We have applied this technique
to the observations of Spartan 201-05 on 1–2 November, 1998, SOHO and Ulysses during the rising phase of this solar cycle and speculate on what solar wind velocities Ulysses will observe during its polar passes over the south and the north poles during September of 2000 and 2001. In order to do
this the model has been generalized to include multiple streamer belts and co-located current sheets. The model shows some
interesting new results.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
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C. S. Arridge N. Andr�� H. J. McAndrews E. J. Bunce M. H. Burger K. C. Hansen H.-W. Hsu R. E. Johnson G. H. Jones S. Kempf K. K. Khurana N. Krupp W. S. Kurth J. S. Leisner C. Paranicas E. Roussos C. T. Russell P. Schippers E. C. Sittler H. T. Smith M. F. Thomsen M. K. Dougherty 《Space Science Reviews》2011,164(1-4):1-83
Saturn??s rich magnetospheric environment is unique in the solar system, with a large number of active magnetospheric processes and phenomena. Observations of this environment from the Cassini spacecraft has enabled the study of a magnetospheric system which strongly interacts with other components of the saturnian system: the planet, its rings, numerous satellites (icy moons and Titan) and various dust, neutral and plasma populations. Understanding these regions, their dynamics and equilibria, and how they interact with the rest of the system via the exchange of mass, momentum and energy is important in understanding the system as a whole. Such an understanding represents a challenge to theorists, modellers and observers. Studies of Saturn??s magnetosphere based on Cassini data have revealed a system which is highly variable which has made understanding the physics of Saturn??s magnetosphere all the more difficult. Cassini??s combination of a comprehensive suite of magnetospheric fields and particles instruments with excellent orbital coverage of the saturnian system offers a unique opportunity for an in-depth study of the saturnian plasma and fields environment. In this paper knowledge of Saturn??s equatorial magnetosphere will be presented and synthesised into a global picture. Data from the Cassini magnetometer, low-energy plasma spectrometers, energetic particle detectors, radio and plasma wave instrumentation, cosmic dust detectors, and the results of theory and modelling are combined to provide a multi-instrumental identification and characterisation of equatorial magnetospheric regions at Saturn. This work emphasises the physical processes at work in each region and at their boundaries. The result of this study is a map of Saturn??s near equatorial magnetosphere, which represents a synthesis of our current understanding at the end of the Cassini Prime Mission of the global configuration of the equatorial magnetosphere. 相似文献
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