共查询到20条相似文献,搜索用时 15 毫秒
1.
A. Fedorov A. Opitz J.-A. Sauvaud J. G. Luhmann D. W. Curtis D. E. Larson 《Space Science Reviews》2011,161(1-4):49-62
The IMPACT SWEA instruments on board the twin STEREO spacecraft detect the solar wind electrons with energies between 1 and 2000 eV. The instruments provide 3-dimensional velocity distributions, pitch angle distributions and solar wind properties at two vantage points in the ecliptic at 1 AU. A few days after launch suppression of the low energy solar wind electrons was detected, which makes data analysis challenging and causes a significant loss of information below 50 eV. This paper describes the methods used to both understand the nature of the problem and to recover the most information about the low energy solar wind electrons from the measured datasets. These include numerical simulations, in-flight calibration results, and data reconstruction methods that allow the calculation of solar wind parameter proxies with minor limitations. 相似文献
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Solar Wind Electron Proton Alpha Monitor (SWEPAM) for the Advanced Composition Explorer 总被引:1,自引:0,他引:1
McComas D.J. Bame S.J. Barker P. Feldman W.C. Phillips J.L. Riley P. Griffee J.W. 《Space Science Reviews》1998,86(1-4):563-612
The Solar Wind Electron Proton Alpha Monitor (SWEPAM) experiment provides the bulk solar wind observations for the Advanced
Composition Explorer (ACE). These observations provide the context for elemental and isotopic composition measurements made
on ACE as well as allowing the direct examination of numerous solar wind phenomena such as coronal mass ejections, interplanetary
shocks, and solar wind fine structure, with advanced, 3-D plasma instrumentation. They also provide an ideal data set for
both heliospheric and magnetospheric multi-spacecraft studies where they can be used in conjunction with other, simultaneous
observations from spacecraft such as Ulysses. The SWEPAM observations are made simultaneously with independent electron and
ion instruments. In order to save costs for the ACE project, we recycled the flight spares from the joint NASA/ESA Ulysses
mission. Both instruments have undergone selective refurbishment as well as modernization and modifications required to meet
the ACE mission and spacecraft accommodation requirements. Both incorporate electrostatic analyzers whose fan-shaped fields
of view sweep out all pertinent look directions as the spacecraft spins. Enhancements in the SWEPAM instruments from their
original forms as Ulysses spare instruments include (1) a factor of 16 increase in the accumulation interval (and hence sensitivity)
for high energy, halo electrons; (2) halving of the effective ion-detecting CEM spacing from ∼5° on Ulysses to ∼2.5° for ACE;
and (3) the inclusion of a 20° conical swath of enhanced sensitivity coverage in order to measure suprathermal ions outside
of the solar wind beam. New control electronics and programming provide for 64-s resolution of the full electron and ion distribution
functions and cull out a subset of these observations for continuous real-time telemetry for space weather purposes.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
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Issautier Karine Hoang Sang Moncuquet Michel Meyer-Vernet Nicole 《Space Science Reviews》2001,97(1-4):105-108
The Ulysses spacecraft is reaching high heliolatitudes during the approach to solar maximum. We show preliminary in situ electron observations
from the URAP experiment, using thermal noise spectroscopy. This method is especially suited to measure accurately the electron
density and thermal temperature. The data acquired in the period June–September 2000 are compared to those obtained at similar
heliolatitudes near solar activity minimum and in the ecliptic plane near both solar maximum and minimum.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
7.
D. McComas F. Allegrini F. Bagenal P. Casey P. Delamere D. Demkee G. Dunn H. Elliott J. Hanley K. Johnson J. Langle G. Miller S. Pope M. Reno B. Rodriguez N. Schwadron P. Valek S. Weidner 《Space Science Reviews》2008,140(1-4):261-313
The Solar Wind Around Pluto (SWAP) instrument on New Horizons will measure the interaction between the solar wind and ions created by atmospheric loss from Pluto. These measurements provide a characterization of the total loss rate and allow us to examine the complex plasma interactions at Pluto for the first time. Constrained to fit within minimal resources, SWAP is optimized to make plasma-ion measurements at all rotation angles as the New Horizons spacecraft scans to image Pluto and Charon during the flyby. To meet these unique requirements, we combined a cylindrically symmetric retarding potential analyzer with small deflectors, a top-hat analyzer, and a redundant/coincidence detection scheme. This configuration allows for highly sensitive measurements and a controllable energy passband at all scan angles of the spacecraft. 相似文献
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Nordholt Jane E. Wiens Roger C. Abeyta Rudy A. Baldonado Juan R. Burnett Donald S. Casey Patrick Everett Daniel T. Kroesche Joseph Lockhart Walter L. MacNeal Paul McComas David J. Mietz Donald E. Moses Ronald W. Neugebauer Marcia Poths Jane Reisenfeld Daniel B. Storms Steven A. Urdiales Carlos 《Space Science Reviews》2003,105(3-4):561-599
The primary goal of the Genesis Mission is to collect solar wind ions and, from their analysis, establish key isotopic ratios
that will help constrain models of solar nebula formation and evolution. The ratios of primary interest include 17O/16O and 18O/16O to ±0.1%, 15N/14N to ±1%, and the Li, Be, and B elemental and isotopic abundances. The required accuracies in N and O ratios cannot be achieved
without concentrating the solar wind and implanting it into low-background target materials that are returned to Earth for
analysis. The Genesis Concentrator is designed to concentrate the heavy ion flux from the solar wind by an average factor
of at least 20 and implant it into a target of ultra-pure, well-characterized materials. High-transparency grids held at high
voltages are used near the aperture to reject >90% of the protons, avoiding damage to the target. Another set of grids and
applied voltages are used to accelerate and focus the remaining ions to implant into the target. The design uses an energy-independent
parabolic ion mirror to focus ions onto a 6.2 cm diameter target of materials selected to contain levels of O and other elements
of interest established and documented to be below 10% of the levels expected from the concentrated solar wind. To optimize
the concentration of the ions, voltages are constantly adjusted based on real-time solar wind speed and temperature measurements
from the Genesis ion monitor. Construction of the Concentrator required new developments in ion optics; materials; and instrument
testing and handling.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
9.
Suess S. T. Phillips J. L. McComas D. J. Goldstein B. E. Neugebauer M. Nerney S. 《Space Science Reviews》1998,83(1-2):75-86
The solar wind in the inner heliosphere, inside ~ 5 AU, has been almost fully characterized by the addition of the high heliographic latitude Ulysses mission to the many low latitude inner heliosphere missions that preceded it. The two major omissions are the high latitude solar wind at solar maximum, which will be measured during the second Ulysses polar passages, and the solar wind near the Sun, which could be analyzed by a Solar Probe mission. Here, existing knowledge of the global solar wind in the inner heliosphere is summarized in the context of the new results from Ulysses. 相似文献
10.
Although coronal mass ejections have traditionally been thought to contribute only a minor fraction to the total solar particle
flux, and although such events mainly occur in lower heliographic latitudes, the impressive spectacle of eruptions - observed
with SOHO/LASCO even at times of solar minimum - indicates that an important part of the low-latitude solar corona is fed
with matter and magnetic fields in a highly transient manner. Elemental and isotopic abundances determined with the new generation
of particle instruments with high sensitivity and strongly enhanced time resolution indicate that, apart from FIP/FIT-fractionation,
mass-dependent fractionation can also influence the replenishment of the thermal ion population of the corona. Furthermore,
selective enrichment of the thermal coronal plasma with rare species such as 3He can occur. Such compositional features have until recently only been found in energetic particles from impulsive flare
events. This review will concentrate on this and other aspects of the present solar maximum and conclude with some outlook
on future investigations of near-terrestrial space climate (the generalized counterpart of ‘space weather’).
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
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The solar wind evolves as it moves outward due to interactions with both itself and with the circum-heliospheric interstellar medium. The speed is, on average, constant out to 30 AU, then starts a slow decrease due to the pickup of interstellar neutrals. These neutrals reduce the solar wind speed by about 20% before the termination shock (TS). The pickup ions heat the thermal plasma so that the solar wind temperature increases outside 20–30 AU. Solar cycle effects are important; the solar wind pressure changes by a factor of 2 over a solar cycle and the structure of the solar wind is modified by interplanetary coronal mass ejections (ICMEs) near solar maximum. The first direct evidences of the TS were the observations of streaming energetic particles by both Voyagers 1 and 2 beginning about 2 years before their respective TS crossings. The second evidence was a slowdown in solar wind speed commencing 80 days before Voyager 2 crossed the TS. The TS was a weak, quasi-perpendicular shock which transferred the solar wind flow energy mainly to the pickup ions. The heliosheath has large fluctuations in the plasma and magnetic field on time scales of minutes to days. 相似文献
13.
Wiens Roger C. Neugebauer Marcia Reisenfeld Daniel B. Moses Ronald W. Nordholt Jane E. Burnett Donald S. 《Space Science Reviews》2003,105(3-4):601-626
The design and operation of the Genesis Solar-Wind Concentrator relies heavily on computer simulations. The computer model
is described here, as well as the solar wind conditions used as simulation inputs, including oxygen charge state, velocity,
thermal, and angular distributions. The simulation included effects such as ion backscattering losses, which also affect the
mass fractionation of the instrument. Calculations were performed for oxygen, the principal element of interest, as well as
for H and He. Ion fluences and oxygen mass fractionation are determined as a function of radius on the target. The results
were used to verify that the instrument was indeed meeting its requirements, and will help prepare for distribution of the
target samples upon return of the instrument to earth. The actual instrumental fractionation will be determined at that time
by comparing solar-wind neon isotope ratios measured in passive collectors with neon in the Concentrator target, and by using
a model similar to the one described here to extrapolate the instrumental fractionation to oxygen isotopes.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
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Möbius E. Kistler L.M. Popecki M.A. Crocker K.N. Granoff M. Turco S. Anderson A. Demain P. Distelbrink J. Dors I. Dunphy P. Ellis S. Gaidos J. Googins J. Hayes R. Humphrey G. Kästle H. Lavasseur J. Lund E.J. Miller R. Sartori E. Shappirio M. Taylor S. Vachon P. Vosbury M. Ye V. Hovestadt D. Klecker B. Arbinger H. Künneth E. Pfeffermann E. Seidenschwang E. Gliem F. Reiche K.-U. Stöckner K. Wiewesiek W. Harasim A. Schimpfle J. Battell S. Cravens J. Murphy G. 《Space Science Reviews》1998,86(1-4):449-495
The Solar Energetic Particle Ionic Charge Analyzer (SEPICA) is the main instrument on the Advanced Composition Explorer (ACE)
to determine the ionic charge states of solar and interplanetary energetic particles in the energy range from ≈0.2 MeV nucl−1
to ≈5 MeV charge−1. The charge state of energetic ions contains key information to unravel source temperatures, acceleration,
fractionation and transport processes for these particle populations. SEPICA will have the ability to resolve individual charge
states and have a substantially larger geometric factor than its predecessor ULEZEQ on ISEE-1 and -3, on which SEPICA is based.
To achieve these two requirements at the same time, SEPICA is composed of one high-charge resolution sensor section and two
low- charge resolution, but large geometric factor sections. The charge resolution is achieved by the focusing of the incoming
ions, through a multi-slit mechanical collimator, deflection in an electrostatic analyzer with a voltage up to 30 kV, and
measurement of the impact position in the detector system. To determine the nuclear charge (element) and energy of the incoming
ions, the combination of thin-window flow-through proportional counters with isobutane as counter gas and ion-implanted solid
state detectors provide for 3 independent ΔE (energy loss) versus E (residual energy) telescopes. The multi-wire proportional
counter simultaneously determines the energy loss ΔE and the impact position of the ions. Suppression of background from penetrating
cosmic radiation is provided by an anti-coincidence system with a CsI scintillator and Si-photodiodes. The data are compressed
and formatted in a data processing unit (S3DPU) that also handles the commanding and various automatted functions of the instrument.
The S3DPU is shared with the Solar Wind Ion Charge Spectrometer (SWICS) and the Solar Wind Ion Mass Spectrometer (SWIMS) and
thus provides the same services for three of the ACE instruments. It has evolved out of a long family of data processing units
for particle spectrometers.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
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Stuart D. Jordan 《Space Science Reviews》1981,29(4):333-340
The Solar Optical Telescope (SOT), which NASA plans to operate on Spacelab, should provide resolution down to 0.1 arc sec, thus offering the capability for solving a number of fundamental problems in solar magnetism and in atmospheric heating and dynamics.Proceedings of the Conference Solar Physics from Space, held at the Swiss Federal Institute of Technology Zurich (ETHZ), 11–14 November 1980. 相似文献
17.
On the Slow Solar Wind 总被引:1,自引:0,他引:1
A theory for the origin of the slow solar wind is described. Recent papers have demonstrated that magnetic flux moves across
coronal holes as a result of the interplay between the differential rotation of the photosphere and the non-radial expansion
of the solar wind in more rigidly rotating coronal holes. This flux will be deposited at low latitudes and should reconnect
with closed magnetic loops, thereby releasing material from the loops to form the slow solar wind. It is pointed out that
this mechanism provides a natural explanation for the charge states of elements observed in the slow solar wind, and for the
presence of the First-Ionization Potential, or FIP, effect in the slow wind and its absence in fast wind. Comments are also
provided on the role that the ACE mission should have in understanding the slow solar wind.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
18.
The Solar Wind in the Outer Heliosphere and Heliosheath 总被引:1,自引:1,他引:0
The solar wind environment has a large influence on the transport of cosmic rays. This chapter discusses the observations of the solar wind plasma and magnetic field in the outer heliosphere and the heliosheath. In the supersonic solar wind, interaction regions with large magnetic fields form barriers to cosmic ray transport. This effect, the “CR-B” relationship, has been quantified and is shown to be valid everywhere inside the termination shock (TS). In the heliosheath, this relationship breaks down, perhaps because of a change in the nature of the turbulence. Turbulence is compressive in the heliosheath, whereas it was non-compressive in the solar wind. The plasma pressure in the outer heliosphere is dominated by the pickup ions which gain most of the flow energy at the TS. The heliosheath plasma and magnetic field are highly variable on scales as small as ten minutes. The plasma flow turns away from the nose roughly as predicted, but the radial speeds at Voyager 1 are much less than those at Voyager 2, which is not understood. Despite predictions to the contrary, magnetic reconnection is not an important process in the inner heliosheath with only one observed occurrence to date. 相似文献
19.
Brian E. Wood 《Space Science Reviews》2006,126(1-4):3-14
Exposure to the solar wind can have significant long term consequences for planetary atmospheres, especially for planets such
as Mars that are not protected by global magnetospheres. Estimating the effects of solar wind exposure requires knowledge
of the history of the solar wind. Much of what we know about the Sun’s past behavior is based on inferences from observations
of young solar-like stars. Stellar analogs of the weak solar wind cannot be detected directly, but the interaction regions
between these winds and the interstellar medium have been detected and used to estimate wind properties. I here review these
observations, with emphasis on what they suggest about the history of the solar wind. 相似文献
20.
J. C. Raymond 《Space Science Reviews》1999,87(1-2):55-66
Order of magnitude variations in relative elemental abundances are observed in the solar corona and solar wind. The instruments
aboard SOHO make it possible to explore these variations in detail to determine whether they arise near the solar surface
or higher in the corona. A substantial enhancement of low First Ionization Potential (FIP) elements relative to high FIP elements
is often seen in both the corona and the solar wind, and that must arise in the chromosphere. Several theoretical models have
been put forward to account for the FIP effect, but as yet even the basic physical mechanism responsible remains an open question.
Evidence for gravitational settling is also found at larger heights in quiescent streamers. The question is why the heavier
elements don't settle out completely.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献