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Sample records for genesis solar-wind sample

  1. Genesis Solar Wind Samples: Update of Availability

    Science.gov (United States)

    Gonzalez, C. P.; Allums, K. K.; Allton, J. H.

    2015-01-01

    The Genesis mission collected solar wind atoms for 28 months with a variety of collectors. The array wafer collector availability is displayed in the online catalog. The purpose of this report is to update the community on availability of array wafer samples and to preview other collectors which are in the process of being added to the online catalog. A total of fifteen pure materials were selected based on engineering and science requirements. Most of the materials were semiconductor wafers which were mounted on the arrays.

  2. The genesis solar-wind sample return mission

    Energy Technology Data Exchange (ETDEWEB)

    Wiens, Roger C [Los Alamos National Laboratory

    2009-01-01

    The compositions of the Earth's crust and mantle, and those of the Moon and Mars, are relatively well known both isotopically and elementally. The same is true of our knowledge of the asteroid belt composition, based on meteorite analyses. Remote measurements of Venus, the Jovian atmosphere, and the outer planet moons, have provided some estimates of their compositions. The Sun constitutes a large majority, > 99%, of all the matter in the solar system. The elemental composition of the photosphere, the visible 'surface' of the Sun, is constrained by absorption lines produced by particles above the surface. Abundances for many elements are reported to the {+-}10 or 20% accuracy level. However, the abundances of other important elements, such as neon, cannot be determined in this way due to a relative lack of atomic states at low excitation energies. Additionally and most importantly, the isotopic composition of the Sun cannot be determined astronomically except for a few species which form molecules above sunspots, and estimates derived from these sources lack the accuracy desired for comparison with meteoritic and planetary surface samples measured on the Earth. The solar wind spreads a sample of solar particles throughout the heliosphere, though the sample is very rarified: collecting a nanogram of oxygen, the third most abundant element, in a square centimeter cross section at the Earth's distance from the Sun takes five years. Nevertheless, foil collectors exposed to the solar wind for periods of hours on the surface of the Moon during the Apollo missions were used to determine the helium and neon solar-wind compositions sufficiently to show that the Earth's atmospheric neon was significantly evolved relative to the Sun. Spacecraft instruments developed subsequently have provided many insights into the composition of the solar wind, mostly in terms of elemental composition. These instruments have the advantage of observing a number of

  3. Genesis Solar Wind Interstream, Coronal Hole and Coronal Mass Ejection Samples: Update on Availability and Condition

    Science.gov (United States)

    Allton, J. H.; Gonzalez, C. P.; Allums, K. K.

    2017-01-01

    Recent refinement of analysis of ACE/SWICS data (Advanced Composition Explorer/Solar Wind Ion Composition Spectrometer) and of onboard data for Genesis Discovery Mission of 3 regimes of solar wind at Earth-Sun L1 make it an appropriate time to update the availability and condition of Genesis samples specifically collected in these three regimes and currently curated at Johnson Space Center. ACE/SWICS spacecraft data indicate that solar wind flow types emanating from the interstream regions, from coronal holes and from coronal mass ejections are elementally and isotopically fractionated in different ways from the solar photosphere, and that correction of solar wind values to photosphere values is non-trivial. Returned Genesis solar wind samples captured very different kinds of information about these three regimes than spacecraft data. Samples were collected from 11/30/2001 to 4/1/2004 on the declining phase of solar cycle 23. Meshik, et al is an example of precision attainable. Earlier high precision laboratory analyses of noble gases collected in the interstream, coronal hole and coronal mass ejection regimes speak to degree of fractionation in solar wind formation and models that laboratory data support. The current availability and condition of samples captured on collector plates during interstream slow solar wind, coronal hole high speed solar wind and coronal mass ejections are de-scribed here for potential users of these samples.

  4. Decontaminating Solar Wind Samples with the Genesis Ultra-Pure Water Megasonic Wafer Spin Cleaner

    Science.gov (United States)

    Calaway, Michael J.; Rodriquez, M. C.; Allton, J. H.; Stansbery, E. K.

    2009-01-01

    The Genesis sample return capsule, though broken during the landing impact, contained most of the shattered ultra-pure solar wind collectors comprised of silicon and other semiconductor wafers materials. Post-flight analysis revealed that all wafer fragments were littered with surface particle contamination from spacecraft debris as well as soil from the impact site. This particulate contamination interferes with some analyses of solar wind. In early 2005, the Genesis science team decided to investigate methods for removing the surface particle contamination prior to solar wind analysis.

  5. Genesis Solar Wind Collector Cleaning Assessment: 60366 Sample Case Study

    Science.gov (United States)

    Goreva, Y. S.; Gonzalez, C. P.; Kuhlman, K. R.; Burnett, D. S.; Woolum, D.; Jurewicz, A. J.; Allton, J. H.; Rodriguez, M. C.; Burkett, P. J.

    2014-01-01

    In order to recognize, localize, characterize and remove particle and thin film surface contamination, a small subset of Genesis mission collector fragments are being subjected to extensive study via various techniques [1-5]. Here we present preliminary results for sample 60336, a Czochralski silicon (Si-CZ) based wafer from the bulk array (B/C).

  6. A 15N-poor isotopic composition for the solar system as shown by Genesis solar wind samples.

    Science.gov (United States)

    Marty, B; Chaussidon, M; Wiens, R C; Jurewicz, A J G; Burnett, D S

    2011-06-24

    The Genesis mission sampled solar wind ions to document the elemental and isotopic compositions of the Sun and, by inference, of the protosolar nebula. Nitrogen was a key target element because the extent and origin of its isotopic variations in solar system materials remain unknown. Isotopic analysis of a Genesis Solar Wind Concentrator target material shows that implanted solar wind nitrogen has a (15)N/(14)N ratio of 2.18 ± 0.02 × 10(-3) (that is, ≈40% poorer in (15)N relative to terrestrial atmosphere). The (15)N/(14)N ratio of the protosolar nebula was 2.27 ± 0.03 × 10(-3), which is the lowest (15)N/(14)N ratio known for solar system objects. This result demonstrates the extreme nitrogen isotopic heterogeneity of the nascent solar system and accounts for the (15)N-depleted components observed in solar system reservoirs.

  7. Genesis Solar Wind Collector Cleaning Assessment: Update on 60336 Sample Case Study

    Science.gov (United States)

    Goreva, Y. S.; Allums, K. K.; Gonzalez, C. P.; Jurewicz, A. J.; Burnett, D. S.; Allton, J. H.; Kuhlman, K. R.; Woolum, D.

    2015-01-01

    To maximize the scientific return of Genesis Solar Wind return mission it is necessary to characterize and remove a crash-derived particle and thin film surface contamination. A small subset of Genesis mission collector fragments are being subjected to extensive study via various techniques. Here we present an update on the sample 60336, a Czochralski silicon (Si-CZ) based wafer from the bulk array (B/C). This sample has undergone multiple cleaning steps (see the table below): UPW spin wash, aggressive chemical cleanings (including aqua regia, hot xylene and RCA1), as well as optical and chemical (EDS, ToF-SIMS) imaging. Contamination appeared on the surface of 60336 after the initial 2007 UPW cleaning. Aqua regia and hot xylene treatment (8/13/2013) did little to remove contaminants. The sample was UPW cleaned for the third time and imaged (9/16/13). The UPW removed the dark stains that were visible on the sample. However, some features, like "the Flounder" (a large, 100 micron feature in Fig. 1b) appeared largely intact, resisting all previous cleaning efforts. These features were likely from mobilized adhesive, derived from the Post-It notes used to stabilize samples for transport from Utah after the hard landing. To remove this contamination, an RCA step 1 organic cleaning (RCA1) was employed. Although we are still uncertain on the nature of the Flounder and why it is resistant to UPW and aqua regia/hot xylene treatment, we have found RCA1 to be suitable for its removal. It is likely that the glue from sticky pads used during collector recovery may have been a source for resistant organic contamination [9]; however [8] shows that UPW reaction with crash-derived organic contamination does not make particle removal more difficult.

  8. Genesis Solar Wind Array Collector Cataloging Status

    Science.gov (United States)

    Burkett, P.J.; Rodriguez, M.C.; Calaway, M.C.; Allton, J.H.

    2009-01-01

    Genesis solar wind array collectors were fractured upon landing hard in Utah in 2004. The fragments were retrieved from the damaged canister, imaged, repackaged and shipped to the Johnson Space Center curatorial facility [1]. As of January 2009, the collection consists of 3460 samples. Of these, 442 are comprised into "multiple" sample groupings, either affixed to adhesive paper (177) or collected in jars (17), culture trays (87), or sets of polystyrene vials (161). A focused characterization task was initiated in May 2008 to document the largest samples in the collection. The task consisted of two goals: to document sapphire based fragments greater than 2 cm in one dimension, and to document silicon based fragments greater than 1 cm in one direction.

  9. Enhanced Cleaning of Genesis Solar Wind Sample 61348 for Film Residue Removal

    Science.gov (United States)

    Allums, K. K.; Gonzalez, C. P.; Kuhlman, K. R.; Allton, J. H.

    2015-01-01

    The Genesis mission returned to Earth on September 8, 2004, experiencing a nonnominal reentry. During the recovery of the collector materials from the capsule, many of the collector fragments were placed on the adhesive protion of post-it notes to prevent the fragments from moving during transport back to Johnson Space Center. This unknowingly provided an additional contaminate that would prove difficult to remove with the limited chemistries allowed in the Genesis Curation Laboratory. Generally when collector material samples are prepared for allocation to PIs, the samples are cleaned front side only with Ultra-Pure Water (UPW) via megasonic dispersion to the collector surface to remove crash debris and contamination. While this cleaning method works well on samples that were not placed on post-its during recovery, it has caused movement of the residue on the back of the sample to be deposited on the front in at least two examples. Therefore, samples placed on the adhesive portion on post-it note, require enhanced cleaning methods since post-it residue has proved resistant to UPW cleaning.

  10. Development of Genesis Solar Wind Sample Cleanliness Assessment: Initial Report on Sample 60341 Optical Imagery and Elemental Mapping

    Science.gov (United States)

    Gonzalez, C. P.; Goreva, Y. S.; Burnett, D. S.; Woolum, D.; Jurewicz, A. J.; Allton, J. H.; Rodriguez, P. J.; Burkett, P. J.

    2014-01-01

    Since 2005 the Genesis science team has experimented with techniques for removing the contaminant particles and films from the collection surface of the Genesis fragments. A subset of 40 samples have been designated as "cleaning matrix" samples. These are small samples to which various cleaning approaches are applied and then cleanliness is assessed optically, by TRXRF, SEM, ToF-SIMS, XPS, ellipsometry or other means [1-9]. Most of these sam-ples remain available for allocation, with cleanliness assessment data. This assessment allows evaluation of various cleaning techniques and handling or analytical effects. Cleaning techniques investigated by the Genesis community include acid/base etching, acetate replica peels, ion beam, and CO2 snow jet cleaning [10-16]. JSC provides surface cleaning using UV ozone exposure and ultra-pure water (UPW) [17-20]. The UPW rinse is commonly used to clean samples for handling debris between processing by different researchers. Optical microscopic images of the sample taken before and after UPW cleaning show what has been added or removed during the cleaning process.

  11. Genesis Solar Wind Sample 61422: Experiment in Variation of Sequence of Cleaning Solvent for Removing Carbon-Bearing Contamination

    Science.gov (United States)

    Allton, J. H.; Kuhlman, K. R.; Allums, K. K.; Gonzalez, C. P.; Jurewicz, A. J. G.; Burnett, D. S.; Woolum, D. S.

    2015-01-01

    The recovered Genesis collector fragments are heavily contaminated with crash-derived particulate debris. However, megasonic treatment with ultra-pure-water (UPW; resistivity (is) greater than18 meg-ohm-cm) removes essentially all particulate contamination greater than 5 microns in size [e.g.1] and is thus of considerable importance. Optical imaging of Si sample 60336 revealed the presence of a large C-rich particle after UPW treatment that was not present prior to UPW. Such handling contamination is occasionally observed, but such contaminants are normally easily removed by UPW cleaning. The 60336 particle was exceptional in that, surprisingly, it was not removed by additional UPW or by hot xylene or by aqua regia treatment. It was eventually removed by treatment with NH3-H2O2. Our best interpretation of the origin of the 60336 particle was that it was adhesive from the Post-It notes used to stabilize samples for transport from Utah after the hard landing. It is possible that the insoluble nature of the 60336 particle comes from interaction of the Post-It adhesive with UPW. An occasional bit of Post-It adhesive is not a major concern, but C particulate contamination also occurs from the heat shield of the Sample Return Capsule (SRC) and this is mixed with inorganic contamination from the SRC and the Utah landing site. If UPW exposure also produced an insoluble residue from SRC C, this would be a major problem in chemical treatments to produce clean surfaces for analysis. This paper reports experiments to test whether particulate contamination was removed more easily if UPW treatment was not used.

  12. Exodus: redirecting Genesis for solar wind observations 4-8 million km from Earth

    Science.gov (United States)

    Steinberg, J.; Barraclough, B.; Gosling, J.; Reisenfeld, D.; Wiens, R.; Liewer, P.; Murphy, N.

    2003-04-01

    Genesis is an ongoing NASA Discovery mission designed to collect samples of the solar wind at L1 and return them to Earth for analysis. After the return capsule is dropped off in September, 2004, the spacecraft, with its in situ solar wind ion and electron spectrometers, is available to perform a new solar wind mission. Spacecraft capabilities, including ample remaining Dv, allow it to achieve and maintain a distant retrograde orbit, a heliocentric orbit in which the spacecraft spends a significant amount of time ˜0.025 AU upstream and downstream of Earth (˜2.5x the Earth-L1 distance). From this orbit Genesis observations may be used, together with those from available L1 spacecraft, to compare solar wind parameters across important spatial scales. The multi-point collaborative studies will uniquely allow us to understand the propagation and evolution of solar wind plasma, as well as the internal spatial structure of large solar wind transients, for spacecraft separation distances of 0.025 to 0.05 AU. Such separation distances are significantly greater than can be attained between any pair of current and proposed satellites in Earth or in L1 halo orbits. At the same time the separations will be small enough to allow confident tracking of particular solar wind structures between spacecraft. In addition to groundbreaking science, the Genesis spacecraft would be a pathfinder for potential future space weather sentinels. We present a proposal to redirect the Genesis spacecraft after its prime mission is complete, and create a new, inexpensive mission: EXODUS.

  13. Genesis Solar Wind Science Canister Components Curated as Potential Solar Wind Collectors and Reference Contamination Sources

    Science.gov (United States)

    Allton, J. H.; Gonzalez, C. P.; Allums, K. K.

    2016-01-01

    The Genesis mission collected solar wind for 27 months at Earth-Sun L1 on both passive and active collectors carried inside of a Science Canister, which was cleaned and assembled in an ISO Class 4 cleanroom prior to launch. The primary passive collectors, 271 individual hexagons and 30 half-hexagons of semiconductor materials, are described in. Since the hard landing reduced the 301 passive collectors to many thousand smaller fragments, characterization and posting in the online catalog remains a work in progress, with about 19% of the total area characterized to date. Other passive collectors, surfaces of opportunity, have been added to the online catalog. For species needing to be concentrated for precise measurement (e.g. oxygen and nitrogen isotopes) an energy-independent parabolic ion mirror focused ions onto a 6.2 cm diameter target. The target materials, as recovered after landing, are described in. The online catalog of these solar wind collectors, a work in progress, can be found at: http://curator.jsc.nasa.gov/gencatalog/index.cfm This paper describes the next step, the cataloging of pieces of the Science Canister, which were surfaces exposed to the solar wind or component materials adjacent to solar wind collectors which may have contributed contamination.

  14. Investigation of Backside Textures for Genesis Solar Wind Silicon Collectors

    Science.gov (United States)

    Gonzalez, C. P.; Burkett, P. J.; Rodriguez, M. C.; Allton, J. H.

    2014-01-01

    Genesis solar wind collectors were comprised of a suite of 15 types of ultrapure materials. The single crystal, pure silicon collectors were fabricated by two methods: float zone (FZ) and Czochralski (CZ). Because of slight differences in bulk purity and surface cleanliness among the fabrication processes and the specific vendor, it is desirable to know which variety of silicon and identity of vendor, so that appropriate reference materials can be used. The Czochralski method results in a bulk composition with slightly higher oxygen, for example. The CZ silicon array wafers that were Genesis-flown were purchased from MEMC Electronics. Most of the Genesis-flown FZ silicon was purchased from Unisil and cleaned by MEMC, although a few FZ wafers were acquired from International Wafer Service (IWS).

  15. Solar and solar-wind composition results from the genesis mission

    Energy Technology Data Exchange (ETDEWEB)

    Wiens, Roger C. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Burnett, D. S. [Geological and Planetary Sciences, Pasadena, CA (United States); Hohenberg, C. M. [Washington Univ., St. Louis, MO (United States); Meshik, A. [Isotope Geology, Zurich (Switzerland); Heber, V. [Isotope Geology, Zurich (Switzerland); Grimberg, A. [Isotope Geology, Zurich (Switzerland); Wieler, R. [Univ. of Montana, Missoula, MT (United States); Reisenfeld, D. B. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2007-02-20

    The Genesis mission returned samples of solar wind to Earth in September, 2004 for ground-based analyses of solar-wind composition, particularly for isotope ratios. Substrates, consisting mostly of high-purity semiconductor materials, were exposed to the solar wind at L1 from December 2001 to April 2004. In addition to a bulk sample of the solar wind, separate samples of coronal hole, interstream, and coronal mass ejection material were obtained. While many of the substrates were broken upon landing due to the failure to deploy the parachute, a number of results have been obtained, and most of the primary science objectives will likely be met. These include noble gas (He, Ne, Ar, Kr, and Xe) isotope ratios in the bulk solar wind and in different solarwind regimes, and the nitrogen and oxygen isotope ( 18O/17O/16O) ratios to high precision. The greatest successes to date have been with the noble gases. Light noble gases from bulk solar wind and separate solar-wind regime samples have been analyzed to date. The regime compositions are so far ambiguous on the occurrence of the type of isotopic fractionation expected from Coulomb drag acceleration. Neon results from closed system stepped etching of bulk metallic glass have revealed the nature of isotopic fractionation as a function of depth, which in lunar samples have for years deceptively suggested the presence of a separate solar component. Isotope ratios of the heavy noble gases, nitrogen, and oxygen are still in the process of being measured.

  16. Using Image Pro Plus Software to Develop Particle Mapping on Genesis Solar Wind Collector Surfaces

    Science.gov (United States)

    Rodriquez, Melissa C.; Allton, J. H.; Burkett, P. J.

    2012-01-01

    The continued success of the Genesis mission science team in analyzing solar wind collector array samples is partially based on close collaboration of the JSC curation team with science team members who develop cleaning techniques and those who assess elemental cleanliness at the levels of detection. The goal of this collaboration is to develop a reservoir of solar wind collectors of known cleanliness to be available to investigators. The heart and driving force behind this effort is Genesis mission PI Don Burnett. While JSC contributes characterization, safe clean storage, and benign collector cleaning with ultrapure water (UPW) and UV ozone, Burnett has coordinated more exotic and rigorous cleaning which is contributed by science team members. He also coordinates cleanliness assessment requiring expertise and instruments not available in curation, such as XPS, TRXRF [1,2] and synchrotron TRXRF. JSC participates by optically documenting the particle distributions as cleaning steps progress. Thus, optical document supplements SEM imaging and analysis, and elemental assessment by TRXRF.

  17. Plan for Subdividing Genesis Mission Diamond-on-Silicon 60000 Solar Wind Collector

    Science.gov (United States)

    Burkett, Patti J.; Allton, J. A.; Clemett, S. J.; Gonzales, C. P.; Lauer, H. V., Jr.; Nakamura-Messenger, K.; Rodriquez, M. C.; See, T. H.; Sutter, B.

    2013-01-01

    NASA's Genesis solar wind sample return mission experienced an off nominal landing resulting in broken, albeit useful collectors. Sample 60000 from the collector is comprised of diamond-like-carbon film on a float zone (FZ) silicon wafer substrate Diamond-on-Silicon (DOS), and is highly prized for its higher concentration of solar wind (SW) atoms. A team of scientist at the Johnson Space Center was charged with determining the best, nondestructive and noncontaminating method to subdivide the specimen that would result in a 1 sq. cm subsample for allocation and analysis. Previous work included imaging of the SW side of 60000, identifying the crystallographic orientation of adjacent fragments, and devising an initial cutting plan.

  18. Genesis Sample Catalog

    Data.gov (United States)

    National Aeronautics and Space Administration — The Genesis mission, launched in August 2001, collected solar wind at Earth-Sun L1 location for 28 months, and returned to Earth September 2004 with collectors (very...

  19. Recent Optical and SEM Characterization of Genesis Solar Wind Concentrator Diamond on Silicon Collector

    Science.gov (United States)

    Allton, Judith H.; Rodriquez, M. C.; Burkett, P. J.; Ross, D. K.; Gonzalez, C. P.; McNamara, K. M.

    2013-01-01

    One of the 4 Genesis solar wind concentrator collectors was a silicon substrate coated with diamond-like carbon (DLC) in which to capture solar wind. This material was designed for analysis of solar nitrogen and noble gases [1, 2]. This particular collector fractured during landing, but about 80% of the surface was recovered, including a large piece which was subdivided in 2012 [3, 4, 5]. The optical and SEM imaging and analysis described below supports the subdivision and allocation of the diamond-on-silicon (DOS) concentrator collector.

  20. Cleaning Study of Genesis Sample 60487

    Science.gov (United States)

    Kuhlman, Kim R.; Rodriquez, M. C.; Gonzalez, C. P.; Allton, J. H.; Burnett, D. S.

    2013-01-01

    The Genesis mission collected solar wind and brought it back to Earth in order to provide precise knowledge of solar isotopic and elemental compositions. The ions in the solar wind were stopped in the collectors at depths on the order of 10 to a few hundred nanometers. This shallow implantation layer is critical for scientific analysis of the composition of the solar wind and must be preserved throughout sample handling, cleaning, processing, distribution, preparation and analysis. Particles of Genesis wafers, brine from the Utah Testing Range and an organic film have deleterious effects on many of the high-resolution instruments that have been developed to analyze the implanted solar wind. We have conducted a correlative microscopic study of the efficacy of cleaning Genesis samples with megasonically activated ultrapure water and UV/ozone cleaning. Sample 60487, the study sample, is a piece of float-zone silicon from the B/C array approximately 4.995mm x 4.145 mm in size

  1. VARIATIONS IN SOLAR WIND FRACTIONATION AS SEEN BY ACE/SWICS AND THE IMPLICATIONS FOR GENESIS MISSION RESULTS

    Energy Technology Data Exchange (ETDEWEB)

    Pilleri, P.; Wiens, R. C. [Los Alamos National Laboratory, P.O. Box 1663, Los Alamos (NM) 87545 (United States); Reisenfeld, D. B. [University of Montana, Department of Physics and Astronomy, 32 Campus Drive, Missoula, Montana (United States); Zurbuchen, T. H.; Lepri, S. T.; Shearer, P.; Gilbert, J. A. [Department of Atmospheric, Oceanic, and Space Sciences, University of Michigan, 2455 Hayward Street, Ann Arbor, MI 48109 (United States); Steiger, R. von, E-mail: paolo.pilleri@irap.omp.eu [International Space Science Institute, Hallerstrasse 6, CH-3012 Bern (Switzerland)

    2015-10-10

    We use Advanced Composition Explorer (ACE)/Solar Wind Ion Composition Spectrometer (SWICS) elemental composition data to compare the variations in solar wind (SW) fractionation as measured by SWICS during the last solar maximum (1999–2001), the solar minimum (2006–2009), and the period in which the Genesis spacecraft was collecting SW (late 2001—early 2004). We differentiate our analysis in terms of SW regimes (i.e., originating from interstream or coronal hole flows, or coronal mass ejecta). Abundances are normalized to the low-first ionization potential (low-FIP) ion magnesium to uncover correlations that are not apparent when normalizing to high-FIP ions. We find that relative to magnesium, the other low-FIP elements are measurably fractionated, but the degree of fractionation does not vary significantly over the solar cycle. For the high-FIP ions, variation in fractionation over the solar cycle is significant: greatest for Ne/Mg and C/Mg, less so for O/Mg, and the least for He/Mg. When abundance ratios are examined as a function of SW speed, we find a strong correlation, with the remarkable observation that the degree of fractionation follows a mass-dependent trend. We discuss the implications for correcting the Genesis sample return results to photospheric abundances.

  2. Distribution of solar wind implanted noble gases in lunar samples

    Science.gov (United States)

    Kiko, J.; Kirsten, T.

    1986-01-01

    The distribution of solar wind implanted noble gases in lunar samples depends on implantation energy, fluence, diffusion, radiation damage and erosion. It is known that at least the lighter rare gases are fractionated after implantation, but the redistribution processes, which mainly drive the losses, are not well understood. Some information about this one can get by looking at the concentration profiles of solar wind implanted He-4 measured by the Gas Ion Probe in single lunar grains. The observed profiles were divided in three groups. These groups are illustrated and briefly discussed.

  3. Cleaning Genesis Solar Wind Collectors with Ultrapure Water: Residual Contaminant Particle Analysis

    Science.gov (United States)

    Allton, J. H.; Wentworth, S. J.; Rodriquez, M. C.; Calaway, M. J.

    2008-01-01

    Additional experience has been gained in removing contaminant particles from the surface of Genesis solar wind collectors fragments by using megasonically activated ultrapure water (UPW)[1]. The curatorial facility has cleaned six of the eight array collector material types to date: silicon (Si), sapphire (SAP), silicon-on-sapphire (SOS), diamond-like carbon-on-silicon (DOS), gold-on-sapphire (AuOS), and germanium (Ge). Here we make estimates of cleaning effectiveness using image analysis of particle size distributions and an SEM/EDS reconnaissance of particle chemistry on the surface of UPW-cleaned silicon fragments (Fig. 1). Other particle removal techniques are reported by [2] and initial assessment of molecular film removal is reported by [3].

  4. Small Particulate Contamination Survey Of Genesis Flight Sample 61423

    Science.gov (United States)

    Kuhlman, K. R.; Schmeling, M.; Gonzalez, C. P.; Allums, K. K.; Allton, J. H.; Burnett, D. S.

    2016-01-01

    The Genesis mission collected solar wind and brought it back to Earth in order to provide precise knowledge of solar isotopic and elemental compositions. The ions in the solar wind stop in the collectors at depths on the order of 10 to a few hundred nanometers. This shallow implantation layer is critical for scientific analysis of the composition of the solar wind and must be preserved throughout sample handling, cleaning, processing, distribution, preparation and analysis. We continue to work with the community of scientists analyzing Genesis samples using our unique laboratory facilities -- and, where needed, our unique cleaning techniques -- to significantly enhance the science return from the Genesis mission. This work is motivated by the need to understand the submicron contamination on the collectors in the Genesis payload as recovered from the crash site in the Utah desert, and -- perhaps more importantly -- how to remove it. We continue to evaluate the effectiveness of the wet-chemical "cleaning" steps used by various investigators, to enable them to design improved methods of stripping spacecraft and terrestrial contamination from surfaces while still leaving the solar-wind signal intact.

  5. Laser Subdivision of the Genesis Concentrator Target Sample 60000

    Science.gov (United States)

    Lauer, Howard V., Jr.; Burkett, P. J.; Rodriquez, M. C.; Nakamura-Messenger, K.; Clemett, S. J.; Gonzales, C. P.; Allton, J. H.; McNamara, K. M.; See, T. H.

    2013-01-01

    The Genesis Allocation Committee received a request for 1 square centimeter of the diamond-like-carbon (DLC) concentrator target for the analysis of solar wind nitrogen isotopes. The target consists of a single crystal float zone (FZ) silicon substrate having a thickness on the order of 550 micrometers with a 1.5-3.0 micrometer-thick coating of DLC on the exposed surface. The solar wind is implanted shallowly in the front side DLC. The original target was a circular quadrant with a radius of 3.1 cm; however, the piece did not survive intact when the spacecraft suffered an anomalous landing upon returning to Earth on September 8, 2004. An estimated 75% of the DLC target was recovered in at least 18 fragments. The largest fragment, Genesis sample 60000, has been designated for this allocation and is the first sample to be subdivided using our laser scribing system Laser subdivision has associated risks including thermal diffusion of the implant if heating occurs and unintended breakage during cleavage. A careful detailed study and considerable subdividing practice using non-flight FZ diamond on silicon, DOS, wafers has considerably reduced the risk of unplanned breakage during the cleaving process. In addition, backside scribing reduces the risk of possible thermal excursions affecting the implanted solar wind, implanted shallowly in the front side DLC.

  6. Cellulose Acetate Replica Cleaning Study of Genesis Non-Flight Sample 3CZ00327

    Science.gov (United States)

    Kuhlman, K. R.; Schmeling, M.; Gonzalez, C. P.; Allton, J. H.; Burnett, D. S.

    2014-01-01

    The Genesis mission collected solar wind and brought it back to Earth in order to provide precise knowledge of solar isotopic and elemental compositions. The ions in the solar wind were stopped in the collectors at depths on the order of 10 to a few hundred nanometers. This shallow implantation layer is critical for scientific analysis of the composition of the solar wind and must be preserved throughout sample handling, cleaning, processing, distribution, preparation and analysis. We are working interactively with the community of scientists analyzing Genesis samples, using our unique laboratory facilities -- and, where needed, our unique cleaning techniques -- to significantly enhance the science return from the Genesis mission. This work is motivated by the need to understand the submicron contamination on the collectors in the Genesis payload as recovered from the crash site in the Utah desert, and -- perhaps more importantly -- how to remove it. That is, we are evaluating the effectiveness of the wet-chemical "cleaning" steps used by various investigators, to enable them to design improved methods of stripping terrestrial contamination from surfaces while still leaving the solar-wind signal intact.

  7. Nuts and Bolts - Techniques for Genesis Sample Curation

    Science.gov (United States)

    Burkett, Patti J.; Rodriquez, M. C.; Allton, J. H.

    2011-01-01

    The Genesis curation staff at NASA Johnson Space Center provides samples and data for analysis to the scientific community, following allocation approval by the Genesis Oversight Committee, a sub-committee of CAPTEM (Curation Analysis Planning Team for Extraterrestrial Materials). We are often asked by investigators within the scientific community how we choose samples to best fit the requirements of the request. Here we will demonstrate our techniques for characterizing samples and satisfying allocation requests. Even with a systematic approach, every allocation is unique. We are also providing updated status of the cataloging and characterization of solar wind collectors as of January 2011. The collection consists of 3721 inventoried samples consisting of a single fragment, or multiple fragments containerized or pressed between post-it notes, jars or vials of various sizes.

  8. Variations in solar wind fractionation as seen by ACE/SWICS over a solar cycle and the implications for Genesis Mission results

    CERN Document Server

    Pilleri, P; Zurbuchen, T H; Lepri, S T; Shearer, P; Gilbert, J A; von Steiger, R; Wiens, R C

    2015-01-01

    We use ACE/SWICS elemental composition data to compare the variations in solar wind fractionation as measured by SWICS during the last solar maximum (1999-2001), the solar minimum (2006-2009) and the period in which the Genesis spacecraft was collecting solar wind (late 2001 - early 2004). We differentiate our analysis in terms of solar wind regimes (i.e. originating from interstream or coronal hole flows, or coronal mass ejecta). Abundances are normalized to the low-FIP ion magnesium to uncover correlations that are not apparent when normalizing to high-FIP ions. We find that relative to magnesium, the other low-FIP elements are measurably fractionated, but the degree of fractionation does not vary significantly over the solar cycle. For the high-FIP ions, variation in fractionation over the solar cycle is significant: greatest for Ne/Mg and C/Mg, less so for O/Mg, and the least for He/Mg. When abundance ratios are examined as a function of solar wind speed, we find a strong correlation, with the remarkable ...

  9. Genesis Radiation Environment

    Science.gov (United States)

    Minow, Joseph I.; Altstatt, Richard L.; Skipworth, William C.

    2007-01-01

    The Genesis spacecraft launched on 8 August 2001 sampled solar wind environments at L1 from 2001 to 2004. After the Science Capsule door was opened, numerous foils and samples were exposed to the various solar wind environments during periods including slow solar wind from the streamer belts, fast solar wind flows from coronal holes, and coronal mass ejections. The Survey and Examination of Eroded Returned Surfaces (SEERS) program led by NASA's Space Environments and Effects program had initiated access for the space materials community to the remaining Science Capsule hardware after the science samples had been removed for evaluation of materials exposure to the space environment. This presentation will describe the process used to generate a reference radiation Genesis Radiation Environment developed for the SEERS program for use by the materials science community in their analyses of the Genesis hardware.

  10. ToF-SIMS Investigation of the Effectiveness of Acid-Cleaning procedures for Genesis Solar Wind Collectors

    Science.gov (United States)

    Goreva, Y. S.; Humanyun, M.; Burnett, D. S.; Jurewicz, A. J.; Gonzalez, C. P.

    2014-01-01

    ToF-SIMS images of Genesis sample surfaces contain an incredible amount of important information, but they also show that the crash-derived surface contamination has many components, presenting a challenge to cleaning. Within the variability, we have shown that there are some samples which appear to be clean to begin with, e.g. 60471, and some are more contaminated. Samples 60493 and 60500 are a part of a focused study of the effectiveness of aqua regia and/or sulfuric acid cleaning of small flight Si implanted with Li-6 using ToF-SIMS.

  11. Catastrophic Impact of Silicon on Silicon: Unraveling the Genesis Impact Using Sample 61881

    Science.gov (United States)

    Kuhlman, K. R.; Kim, H.; Jurewicz, A. J. G.; Gonzalez, C. P.; Allums, K. K.

    2016-01-01

    The Genesis mission collected solar wind and brought it back to Earth in order to provide precise knowledge of solar isotopic and elemental compositions. The ions in the solar wind were stopped in the collectors at depths on the order of 10 to a few hundred nanometers. This shallow implantation layer is critical for scientific analysis of the composition of the solar wind and must be preserved throughout sample handling, cleaning, processing, distribution, preparation and analysis. The current work is motivated by the need to understand the interaction of the Genesis payload with contamination during the crash in the Utah desert. Silicon contamination has been found to be notoriously difficult to remove from silicon samples despite multiple cleanings with multiple techniques. However, the question has been posed, "Does the silicon really need to be removed for large area analyses?." If the recalcitrant silicon contamination is all pure silicon from fractured collectors, only a very tiny fraction of that bulk material will contain solar wind, which could skew the analyses. This could be complicated if the silicon trapped other materials and/or gases as it impacted the surface.

  12. Genesis Contingency Planning and Mishap Recovery: The Sample Curation View

    Science.gov (United States)

    Stansbery, E. K.; Allton, J. H.; Allen, C. C.; McNamara, K. M.; Calaway, M.; Rodriques, M. C.

    2007-01-01

    Planning for sample preservation and curation was part of mission design from the beginning. One of the scientific objectives for Genesis included collecting samples of three regimes of the solar wind in addition to collecting bulk solar wind during the mission. Collectors were fabricated in different thicknesses for each regime of the solar wind and attached to separate frames exposed to the solar wind during specific periods of solar activity associated with each regime. The original plan to determine the solar regime sampled for specific collectors was to identify to which frame the collector was attached. However, the collectors were dislodged during the hard landing making identification by frame attachment impossible. Because regimes were also identified by thickness of the collector, the regime sampled is identified by measuring fragment thickness. A variety of collector materials and thin films applied to substrates were selected and qualified for flight. This diversity provided elemental measurement in more than one material, mitigating effects of diffusion rates and/or radiation damage. It also mitigated against different material and substrate strengths resulting in differing effects of the hard landing. For example, silicon crystal substrates broke into smaller fragments than sapphire-based substrates and diamond surfaces were more resilient to flying debris damage than gold. The primary responsibility of the curation team for recovery was process documentation. Contingency planning for the recovery phase expanded this responsibility to include not only equipment to document, but also gather, contain and identify samples from the landing area and the recovered spacecraft. The team developed contingency plans for various scenarios as part of mission planning that included topographic maps to aid in site recovery and identification of different modes of transport and purge capability depending on damage. A clean tent, set-up at Utah Test & Training Range

  13. Nitrogen isotopes in the recent solar wind from the analysis of genesis targets: evidence for large scale isotope heterogeneity in the nascent solar system

    Energy Technology Data Exchange (ETDEWEB)

    Wiens, Roger C [Los Alamos National Laboratory; Marty, Bernard [INSU-CNRS; Zimmermann, Laurent [INSU-CNRS; Burnard, Peter G [INSU-CNRS; Burnett, Donald L [CALTECH; Heber, Veronika S [ETH ZURICH; Wieler, Rainer [ETH ZURICH; Bochsler, Peter [UNIV OV BERN

    2009-01-01

    Nitrogen, the fifth most abundant element in the universe, displays the largest stable isotope variations in the solar system reservoirs after hydrogen. Yet the value of isotopic composition of solar nitrogen, presumably the best proxy of the protosolar nebula composition, is not known. Nitrogen isotopes trapped in Genesis spacecraft target material indicate a 40 % depletion of {sup 15}N in solar wind N relative to inner planets and meteorites, and define a composition for the present-day Sun undistinguishable from that of Jupiter's atmosphere. These results indicate that the isotopic composition of of nitrogen in the outer convective zone of the Sun (OCZ) has not changed through time, and is representative of the protosolar nebula. Large {sup 15}N enrichments during e.g., irradiation, or contributions from {sup 15}N-rich presolar components, are required to account for planetary values.

  14. Examples of Optical Assessment of Surface Cleanliness of Genesis Samples

    Science.gov (United States)

    Rodriquez, Melissa C.; Allton, J. H.; Burkett, P. J.; Gonzalez, C. P.

    2013-01-01

    Optical microscope assessment of Genesis solar wind collector surfaces is a coordinated part of the effort to obtain an assessed clean subset of flown wafer material for the scientific community. Microscopic survey is typically done at 50X magnification at selected approximately 1 square millimeter areas on the fragment surface. This survey is performed each time a principle investigator (PI) returns a sample to JSC for documentation as part of the established cleaning plan. The cleaning plan encompasses sample handling and analysis by Genesis science team members, and optical survey is done at each step in the process. Sample surface cleaning is performed at JSC (ultrapure water [1] and UV ozone cleaning [2]) and experimentally by other science team members (acid etch [3], acetate replica peels [4], CO2 snow [5], etc.). The documentation of each cleaning method can potentially be assessed with optical observation utilizing Image Pro Plus software [6]. Differences in particle counts can be studied and discussed within analysis groups. Approximately 25 samples have been identified as part of the cleaning matrix effort to date.

  15. Coronal sources and in situ properties of the solar winds sampled by ACE during 1999-2008

    CERN Document Server

    Fu, Hui; Li, Xing; Huang, Zhenghua; Mou, Chaozhou; Jiao, Fangran; Xia, Lidong

    2015-01-01

    We identify the coronal sources of the solar winds sampled by the ACE spacecraft during 1999-2008, and examine the in situ solar wind properties as a function of wind sources. The standard two-step mapping technique is adopted to establish the photospheric footpoints of the magnetic flux tubes along which the ACE winds flow. The footpoints are then placed in the context of EIT 284~\\AA\\ images and photospheric magnetograms, allowing us to categorize the sources into four groups: coronal holes (CHs), active regions (ARs), the quiet Sun (QS), and "Undefined". This practice also enables us to establish the response to solar activity of the fractions occupied by each kind of solar winds, and of their speeds and O$^{7+}$/O$^{6+}$ ratios measured in situ. We find that during the maximum phase, the majority of ACE winds originate from ARs. During the declining phase, CHs and ARs are equally important contributors to the ACE solar winds. The QS contribution increases with decreasing solar activity, and maximizes in th...

  16. Constraints on neon and argon isotopic fractionation in solar wind.

    Science.gov (United States)

    Meshik, Alex; Mabry, Jennifer; Hohenberg, Charles; Marrocchi, Yves; Pravdivtseva, Olga; Burnett, Donald; Olinger, Chad; Wiens, Roger; Reisenfeld, Dan; Allton, Judith; McNamara, Karen; Stansbery, Eileen; Jurewicz, Amy J G

    2007-10-19

    To evaluate the isotopic composition of the solar nebula from which the planets formed, the relation between isotopes measured in the solar wind and on the Sun's surface needs to be known. The Genesis Discovery mission returned independent samples of three types of solar wind produced by different solar processes that provide a check on possible isotopic variations, or fractionation, between the solar-wind and solar-surface material. At a high level of precision, we observed no significant inter-regime differences in 20Ne/22Ne or 36Ar/38Ar values. For 20Ne/22Ne, the difference between low- and high-speed wind components is 0.24 +/- 0.37%; for 36Ar/38Ar, it is 0.11 +/- 0.26%. Our measured 36Ar/38Ar ratio in the solar wind of 5.501 +/- 0.005 is 3.42 +/- 0.09% higher than that of the terrestrial atmosphere, which may reflect atmospheric losses early in Earth's history.

  17. Solar wind travel time

    Science.gov (United States)

    Russell, C. T.

    A useful rule of thumb in solar terrestrial studies is that the solar wind travels 4 Earth radii (RE) per minute. Long-term studies of solar wind velocity [e.g., Luhmann et al., 1993; 1994] show that the median velocity is about 420 km/s, corresponding to 3.96 RE min-1. The quartiles are about 370 km/s and 495 km/s, corresponding to 3.48 Re min-1 and 4.66 Re min-1 respectively. This number helps estimate the delays expected when observing a discontinuity at a solar wind monitor; one example is ISEE-3 when it was at the forward libration point (about 60 min). It is also helpful for estimating how much time passes before the dayside magnetosphere is compressed as denser solar wind flows by (about 2.5 min).

  18. Solar Wind Five

    Science.gov (United States)

    Neugebauer, M. (Editor)

    1983-01-01

    Topics of discussion were: solar corona, MHD waves and turbulence, acceleration of the solar wind, stellar coronae and winds, long term variations, energetic particles, plasma distribution functions and waves, spatial dependences, and minor ions.

  19. Solar composition from the Genesis Discovery Mission.

    Science.gov (United States)

    Burnett, D S; Team, Genesis Science

    2011-11-29

    Science results from the Genesis Mission illustrate the major advantages of sample return missions. (i) Important results not otherwise obtainable except by analysis in terrestrial laboratories: the isotopic compositions of O, N, and noble gases differ in the Sun from other inner solar system objects. The N isotopic composition is the same as that of Jupiter. Genesis has resolved discrepancies in the noble gas data from solar wind implanted in lunar soils. (ii) The most advanced analytical instruments have been applied to Genesis samples, including some developed specifically for the mission. (iii) The N isotope result has been replicated with four different instruments.

  20. Ancient solar wind in lunar microbreccias

    Science.gov (United States)

    Thiemens, M. H.; Clayton, R. N.

    1980-03-01

    Possible components of the ancient solar wind, particularly the N-15/N-14 ratio, are investigated on the basis of lunar microbreccia studies. Nitrogen contents and isotope ratios were determined for Apollo 11 and 15 microbreccia samples by means of vacuum pyrolysis techniques. The Apollo 11 soil breccias, which had been closed to the addition of recent solar wind due to their compaction, are found to contain the lowest N-15/N-14 ratios yet reported for the solar wind, extending the range of variation of the ratio to between a delta N-15 of -190% in the past to +120% at present. Nitrogen isotope analysis of the Apollo 15 drill core, which had undergone two episodes of solar wind exposure, also support the secular variation in the N-15 content of the solar wind, which is attributed to spallation reactions in the sun. The formation of the breccias at the Apollo 11 and 15 sites is discussed on the basis of the observed nitrogen systematics, and differences between N-15 and Ne-21 cosmic ray exposure ages implied are attributed to the diffusive loss of neon from lunar soils.

  1. Corona and solar wind

    Science.gov (United States)

    Withbroe, G. L.

    1986-04-01

    The Pinhole/Occulter Facility is a powerful tool for studying the physics of the extended corona and origins of the solar wind. Spectroscopic data acquired by the P/OF coronal instruments can greatly expand empirical information about temperatures, densities, flow velocities, magnetic fields, and chemical abundances in the corona out to r or approx. 10 solar radii. Such information is needed to provide tight empirical constraints on critical physical processes involved in the transport and dissipation of energy and momentum, the heating and acceleration of plasma, and the acceleration of energetic particles. Because of its high sensitivity, high spatial and temporal resolutions, and powerful capabilities for plasma diagnostics, P/OF can significantly increase our empirical knowledge about coronal streamers and transients and thereby advance the understanding of the physics of these phenomena. P/OF observations can be used to establish the role in solar wind generation, if any, of small-scale dynamical phenomena, such as spicules, macrospicules and coronal bullets, and the role of the fine-scale structures, such as polar plumes. Finally, simultaneous measurements by the P/OF coronal and hard X-ray instruments can provide critical empirical information concerning nonthermal energy releases and acceleration of energetic particles in the corona.

  2. Forecasting Solar Wind Speeds

    CERN Document Server

    Suzuki, T K

    2006-01-01

    By explicitly taking into account effects of Alfven waves, I derive from a simple energetics argument a fundamental relation which predicts solar wind (SW) speeds in the vicinity of the earth from physical properties on the sun. Kojima et al. recently found from their observations that a ratio of surface magnetic field strength to an expansion factor of open magnetic flux tubes is a good indicator of the SW speed. I show by using the derived relation that this nice correlation is an evidence of the Alfven wave which accelerates SW in expanding flux tubes. The observations further require that fluctuation amplitudes of magnetic field lines at the surface should be almost universal in different coronal holes, which needs to be tested by future observations.

  3. Comparison of algorithms for determination of solar wind regimes

    Science.gov (United States)

    Neugebauer, Marcia; Reisenfeld, Daniel; Richardson, Ian G.

    2016-09-01

    This study compares the designation of different solar wind flow regimes (transient, coronal hole, and streamer belt) according to two algorithms derived from observations by the Solar Wind Ion Composition Spectrometer, the Solar Wind Electron Proton Alpha Monitor, and the Magnetometer on the ACE spacecraft, with a similar regime determination performed on board the Genesis spacecraft. The comparison is made for the interval from late 2001 to early 2004 when Genesis was collecting solar wind ions for return to Earth. The agreement between hourly regime assignments from any pair of algorithms was less than two thirds, while the simultaneous agreement between all three algorithms was only 49%. When the results of the algorithms were compared to a catalog of interplanetary coronal mass ejection events, it was found that almost all the events in the catalog were confirmed by the spacecraft algorithms. On the other hand, many short transient events, lasting 1 to 13 h, that were unanimously selected as transient like by the algorithms, were not included in the catalog.

  4. Solar Wind Composition: First Results from SOHO and Future Expectations

    Science.gov (United States)

    Galvin, A. B.; Ipavich, F. M.; Gloeckler, G.; Coplan, M.; Hovestadt, D.; Hilchenbach, M.; Buergi, A.; Klecker, B.; Scholer, M.; Bochsler, P.; Balsiger, H.; Geiss, J.; Kallenbach, R.; Wurz, P.; Gruenwaldt, H.; Axford, W. I.; Livi, S.; Marsch, E.; Wilken, B.; Gliem, F.; Reiche, K.-U.; Lee, M. A.; Moebius, E.; Hsieh, K. C.; Neugebauer, M.; Managadze, G. G.; Verigin, M. I.

    1996-05-01

    The SOHO payload includes three experiments designed to make "in situ" particle measurements of the solar wind and solar energetic particles (CELIAS, D. Hovestadt PI; COSTEP, H. Kunow PI; ERNE, J. Torsti PI). The solar wind measurements that are the focus of this talk are primarily provided by the CELIAS CTOF and MTOF sensors. (CELIAS/STOF and COSTEP-ERNE measure solar and interplanetary suprathermal and energetic particle populations.) CELIAS/CTOF measures solar wind heavy ion elemental and charge state abundances, information which is used (for example) in identifying the type of solar wind flow and the ionization processes in the corona where the solar wind charge states become "frozen-in". CELIAS/MTOF provides heavy ion elemental and isotopic abundances that are important (for example) in the study of fractionation factors in coronal abundances (as in the so-called "FIP-effect") for the rarer elements not resolvable in conventional solar wind composition instruments, and in determining the isotopic make-up of the solar corona. MTOF is, by far, the most powerful solar wind mass spectrometer flown to date, and already has new science to report at the time of this writing. This happenstance is due to a combination of (1) advanced technology in obtaining high mass resolution for ions at solar wind energies, and (2) increased statistics. The excellent counting statistics are largely due to continuous solar wind monitoring (with its position at L1, ``the Sun never sets on SOHO''), and the continuous sampling of the solar wind by the 3-axis stabilized spacecraft further enhanced by MTOF's novel, never previously flown deflection system that encompasses a very large dynamic range. As might be expected, this unique opportunity has allowed MTOF to identify a number of elements for the first time in the solar wind (e.g., P, Ti, Cr and Ni). A rich assortment of solar wind isotopes have been identified for the first time, many of which (e.g., Fe 54 and 56; Ni 58,60,62) have

  5. Marshall Space Flight Center's Solar Wind Facility

    Science.gov (United States)

    Wright, K. H.; Schneider, T. A.; Vaughn, J. A.; Whittlesey, P. L.

    2017-01-01

    Historically, NASA's Marshall Space Flight Center (MSFC) has operated a Solar Wind Facility (SWF) to provide long term particle and photon exposure to material samples. The requirements on the particle beam details were not stringent as the cumulative fluence level is the test goal. Motivated by development of the faraday cup instrument on the NASA Solar Probe Plus (SPP) mission, the MSFC SWF has been upgraded to included high fidelity particle beams providing broadbeam ions, broadbeam electrons, and narrow beam protons or ions, which cover a wide dynamic range of solar wind velocity and flux conditions. The large vacuum chamber with integrated cryo-shroud, combined with a 3-axis positioning system, provides an excellent platform for sensor development and qualification. This short paper provides some details of the SWF charged particle beams characteristics in the context of the Solar Probe Plus program requirements. Data will be presented on the flux and energy ranges as well as beam stability.

  6. Charge States of Krypton and Xenon in the Solar Wind

    Science.gov (United States)

    Bochsler, Peter; Fludra, Andrzej; Giunta, Alessandra

    2017-09-01

    We calculate charge state distributions of Kr and Xe in a model for two different types of solar wind using the effective ionization and recombination rates provided from the OPEN_ADAS data base. The charge states of heavy elements in the solar wind are essential for estimating the efficiency of Coulomb drag in the inner corona. We find that xenon ions experience particularly low Coulomb drag from protons in the inner corona, comparable to the notoriously weak drag of protons on helium ions. It has been found long ago that helium in the solar wind can be strongly depleted near interplanetary current sheets, whereas coronal mass ejecta are sometimes strongly enriched in helium. We argue that if the extraordinary variability of the helium abundance in the solar wind is due to inefficient Coulomb drag, the xenon abundance must vary strongly. In fact, a secular decrease of the solar wind xenon abundance relative to the other heavier noble gases (Ne, Ar, Kr) has been postulated based on a comparison of noble gases in recently irradiated and ancient samples of ilmenite in the lunar regolith. We conclude that decreasing solar activity and decreasing frequency of coronal mass ejections over the solar lifetime might be responsible for a secularly decreasing abundance of xenon in the solar wind.

  7. Highly Alfvenic Slow Solar Wind

    Science.gov (United States)

    Roberts, D. Aaron

    2010-01-01

    It is commonly thought that fast solar wind tends to be highly Alfvenic, with strong correlations between velocity and magnetic fluctuations, but examples have been known for over 20 years in which slow wind is both Alfvenic and has many other properties more typically expected of fast solar wind. This paper will present a search for examples of such flows from more recent data, and will begin to characterize the general characteristics of them. A very preliminary search suggests that such intervals are more common in the rising phase of the solar cycle. These intervals are important for providing constraints on models of solar wind acceleration, and in particular the role waves might or might not play in that process.

  8. Solar wind rare gas analysis: Trapped solar wind helium and neon in Surveyor 3 material

    Science.gov (United States)

    Buehler, F.; Eberhardt, P.; Geiss, J.; Schwarzmueller, J.

    1972-01-01

    The He-4 and Ne-20 contents in sections of the Surveyor 3 support strut samples were determined by optical and scanning electron microscopy and are compared to the results of the Apollo solar wind composition (SWC) experiments. The He-4/Ne-20 ratio in the samples from the sunlit side of the strut was approximately 300; the ratios determined in Apollo 12 lunar fines and SWC foil were below 100. The He-4/He-3 ratios were also determined, and the ratio obtained from Surveyor 3 material is higher than those found with Apollo 11 and 12 SWC experiments. The effects of spallation by cosmic rays or solar protons, stripping by cosmic ray or energetic solar alpha particles, recycling of solar wind He and radiogenic Ne, He from terrestrial atmosphere, mass discrimination near the moon, mass dependence of trapping probability, diffusion, and contamination by lunar dust are considered.

  9. Decontamination of Genesis Array Materials by UV Ozone Cleaning

    Science.gov (United States)

    Calaway, Michael J.; Burnett, D. S.; Rodriquez, M. C.; Sestak, S.; Allton, J. H.; Stansbery, E. K.

    2007-01-01

    Shortly after the NASA Genesis Mission sample return capsule returned to earth on September 8, 2004, the science team discovered that all nine ultra-pure semiconductor materials were contaminated with a thin molecular organic film approximately 0 to 100 angstroms thick. The organic contaminate layer, possibly a silicone, situated on the surface of the materials is speculated to have formed by condensation of organic matter from spacecraft off-gassing at the Lagrange 1 halo orbit during times of solar exposure. While the valuable solar wind atoms are safely secured directly below this organic contamination and/or native oxide layer in approximately the first 1000 angstroms of the ultra-pure material substrate, some analytical techniques that precisely measure solar wind elemental abundances require the removal of this organic contaminate. In 2005, Genesis science team laboratories began to develop various methods for removing the organic thin film without removing the precious material substrate that contained the solar wind atoms. Stephen Sestak and colleagues at Open University first experimented with ultraviolet radiation ozone (UV/O3) cleaning of several non-flight and flown Genesis silicon wafer fragments under a pure flowing oxygen environment. The UV/O3 technique was able to successfully remove organic contamination without etching into the bulk material substrate. At NASA Johnson Space Center Genesis Curation Laboratory, we have installed an UV/O3 cleaning devise in an ambient air environment to further experimentally test the removal of the organic contamination on Genesis wafer materials. Preliminary results from XPS analysis show that the UV/O3 cleaning instrument is a good non-destructive method for removing carbon contamination from flown Genesis array samples. However, spectroscopic ellipsometry results show little change in the thickness of the surface film. All experiments to date have shown UV/O3 cleaning method to be the best non-destructive method

  10. The oxygen isotopic composition of the Sun inferred from captured solar wind.

    Science.gov (United States)

    McKeegan, K D; Kallio, A P A; Heber, V S; Jarzebinski, G; Mao, P H; Coath, C D; Kunihiro, T; Wiens, R C; Nordholt, J E; Moses, R W; Reisenfeld, D B; Jurewicz, A J G; Burnett, D S

    2011-06-24

    All planetary materials sampled thus far vary in their relative abundance of the major isotope of oxygen, (16)O, such that it has not been possible to define a primordial solar system composition. We measured the oxygen isotopic composition of solar wind captured and returned to Earth by NASA's Genesis mission. Our results demonstrate that the Sun is highly enriched in (16)O relative to the Earth, Moon, Mars, and bulk meteorites. Because the solar photosphere preserves the average isotopic composition of the solar system for elements heavier than lithium, we conclude that essentially all rocky materials in the inner solar system were enriched in (17)O and (18)O, relative to (16)O, by ~7%, probably via non-mass-dependent chemistry before accretion of the first planetesimals.

  11. Turbulence in the solar wind

    CERN Document Server

    Bruno, Roberto

    2016-01-01

    This book provides an overview of solar wind turbulence from both the theoretical and observational perspective. It argues that the interplanetary medium offers the best opportunity to directly study turbulent fluctuations in collisionless plasmas. In fact, during expansion, the solar wind evolves towards a state characterized by large-amplitude fluctuations in all observed parameters, which resembles, at least at large scales, the well-known hydrodynamic turbulence. This text starts with historical references to past observations and experiments on turbulent flows. It then introduces the Navier-Stokes equations for a magnetized plasma whose low-frequency turbulence evolution is described within the framework of the MHD approximation. It also considers the scaling of plasma and magnetic field fluctuations and the study of nonlinear energy cascades within the same framework. It reports observations of turbulence in the ecliptic and at high latitude, treating Alfvénic and compressive fluctuations separately in...

  12. Sample Return Missions Where Contamination Issues are Critical: Genesis Mission Approach

    Science.gov (United States)

    Allton, Judith H.; Stansbery E. K.

    2011-01-01

    The Genesis Mission, sought the challenging analytical goals of accurately and precisely measuring the elemental and isotopic composition of the Sun to levels useful for planetary science, requiring sensitivities of ppm to ppt in the outer 100 nm of collector materials. Analytical capabilities were further challenged when the hard landing in 2004 broke open the canister containing the super-clean collectors. Genesis illustrates that returned samples allow flexibility and creativity to recover from setbacks.

  13. Cleaning Genesis Sample Return Canister for Flight: Lessons for Planetary Sample Return

    Science.gov (United States)

    Allton, J. H.; Hittle, J. D.; Mickelson, E. T.; Stansbery, Eileen K.

    2016-01-01

    Sample return missions require chemical contamination to be minimized and potential sources of contamination to be documented and preserved for future use. Genesis focused on and successfully accomplished the following: - Early involvement provided input to mission design: a) cleanable materials and cleanable design; b) mission operation parameters to minimize contamination during flight. - Established contamination control authority at a high level and developed knowledge and respect for contamination control across all institutions at the working level. - Provided state-of-the-art spacecraft assembly cleanroom facilities for science canister assembly and function testing. Both particulate and airborne molecular contamination was minimized. - Using ultrapure water, cleaned spacecraft components to a very high level. Stainless steel components were cleaned to carbon monolayer levels (10 (sup 15) carbon atoms per square centimeter). - Established long-term curation facility Lessons learned and areas for improvement, include: - Bare aluminum is not a cleanable surface and should not be used for components requiring extreme levels of cleanliness. The problem is formation of oxides during rigorous cleaning. - Representative coupons of relevant spacecraft components (cut from the same block at the same time with identical surface finish and cleaning history) should be acquired, documented and preserved. Genesis experience suggests that creation of these coupons would be facilitated by specification on the engineering component drawings. - Component handling history is critical for interpretation of analytical results on returned samples. This set of relevant documents is not the same as typical documentation for one-way missions and does include data from several institutions, which need to be unified. Dedicated resources need to be provided for acquiring and archiving appropriate documents in one location with easy access for decades. - Dedicated, knowledgeable

  14. Solar wind thermal electron distributions

    Energy Technology Data Exchange (ETDEWEB)

    Phillips, J.L.; Gosling, J.T.

    1991-01-01

    Solar wind thermal electron distributions exhibit distinctive trends which suggest Coulomb collisions and geometric expansion in the interplanetary magnetic field play keys roles in electron transport. We introduce a simple numerical model incorporating these mechanisms, discuss the ramifications of model results, and assess the validity of the model in terms of ISEE-3 and Ulysses observations. Although the model duplicates the shape of the electron distributions, and explains certain other observational features, observed gradients in total electron temperature indicate the importance of additional heating mechanisms. 5 refs., 7 figs.

  15. Solar wind thermal electron distributions

    Energy Technology Data Exchange (ETDEWEB)

    Phillips, J.L.; Gosling, J.T.

    1991-12-01

    Solar wind thermal electron distributions exhibit distinctive trends which suggest Coulomb collisions and geometric expansion in the interplanetary magnetic field play keys roles in electron transport. We introduce a simple numerical model incorporating these mechanisms, discuss the ramifications of model results, and assess the validity of the model in terms of ISEE-3 and Ulysses observations. Although the model duplicates the shape of the electron distributions, and explains certain other observational features, observed gradients in total electron temperature indicate the importance of additional heating mechanisms. 5 refs., 7 figs.

  16. Contribution of strong discontinuities to the power spectrum of the solar wind.

    Science.gov (United States)

    Borovsky, Joseph E

    2010-09-10

    Eight and a half years of magnetic field measurements (2(22) samples) from the ACE spacecraft in the solar wind at 1 A.U. are analyzed. Strong (large-rotation-angle) discontinuities in the solar wind are collected and measured. An artificial time series is created that preserves the timing and amplitudes of the discontinuities. The power spectral density of the discontinuity series is calculated and compared with the power spectral density of the solar-wind magnetic field. The strong discontinuities produce a power-law spectrum in the "inertial subrange" with a spectral index near the Kolmogorov -5/3 index. The discontinuity spectrum contains about half of the power of the full solar-wind magnetic field over this "inertial subrange." Warnings are issued about the significant contribution of discontinuities to the spectrum of the solar wind, complicating interpretation of spectral power and spectral indices.

  17. Solar wind influence on Jupiter's aurora

    Science.gov (United States)

    Gyalay, Szilard; Vogt, Marissa F.; Withers, Paul; Bunce, Emma J.

    2016-10-01

    Jupiter's main auroral emission is driven by a system of corotation enforcement currents that arises to speed up outflowing Iogenic plasma and is not due to the magnetosphere-solar wind interaction like at Earth. The solar wind is generally expected to have only a small influence on Jupiter's magnetosphere and aurora compared to the influence of rotational stresses due to the planet's rapid rotation. However, there is considerable observational evidence that the solar wind does affect the magnetopause standoff distance, auroral radio emissions, and the position and brightness of the UV auroral emissions. Using the Michigan Solar Wind Model (mSWiM) to predict the solar wind conditions upstream of Jupiter we have identified intervals of high and low solar wind dynamic pressure in the Galileo dataset, and use this information to quantify how a magnetospheric compression affects the magnetospheric field configuration. We have developed separate spatial fits to the compressed and nominal magnetic field data, accounting for variations with radial distance and local time. These two fits can be used to update the flux equivalence mapping model of Vogt et al. (2011), which links auroral features to source regions in the middle and outer magnetosphere. The updated version accounts for changing solar wind conditions and provides a way to quantify the expected solar wind-induced variability in the ionospheric mapping of the main auroral emission, satellite footprints, and other auroral features. Our results are highly relevant to interpretation of the new auroral observations from the Juno mission.

  18. Solar Wind Variation with the Cycle

    Indian Academy of Sciences (India)

    I. S. Veselovsky; A. V. Dmitriev; A. V. Suvorova; M. V. Tarsina

    2000-09-01

    The cyclic evolution of the heliospheric plasma parameters is related to the time-dependent boundary conditions in the solar corona. "Minimal" coronal configurations correspond to the regular appearance of the tenuous, but hot and fast plasma streams from the large polar coronal holes. The denser, but cooler and slower solar wind is adjacent to coronal streamers. Irregular dynamic manifestations are present in the corona and the solar wind everywhere and always. They follow the solar activity cycle rather well. Because of this, the direct and indirect solar wind measurements demonstrate clear variations in space and time according to the minimal, intermediate and maximal conditions of the cycles. The average solar wind density, velocity and temperature measured at the Earth's orbit show specific decadal variations and trends, which are of the order of the first tens per cent during the last three solar cycles. Statistical, spectral and correlation characteristics of the solar wind are reviewed with the emphasis on the cycles.

  19. DSCOVR High Time Resolution Solar Wind Measurements

    Science.gov (United States)

    Szabo, Adam

    2012-01-01

    The Deep Space Climate Observatory (DSCOVR), previously known as Triana, spacecraft is expected to be launched in late 2014. It will carry a fluxgate magnetometer, Faraday Cup solar wind detector and a top-hat electron electrostatic analyzer. The Faraday Cup will provide an unprecedented 10 vectors/sec time resolution measurement of the solar wind proton and alpha reduced distribution functions. Coupled with the 40 vector/sec vector magnetometer measurements, the identification of specific wave modes in the solar wind will be possible for the first time. The science objectives and data products of the mission will be discussed.

  20. Genesis Silicon Carbide Concentrator Target 60003 Preliminary Ellipsometry Mapping Results

    Science.gov (United States)

    Calaway, M. J.; Rodriquez, M. C.; Stansbery, E. K.

    2007-01-01

    The Genesis concentrator was custom designed to focus solar wind ions primarily for terrestrial isotopic analysis of O-17/O-16 and O-18/O-16 to +/-1%, N-15/N-14 to +/-1%, and secondarily to conduct elemental and isotopic analysis of Li, Be, and B. The circular 6.2 cm diameter concentrator target holder was comprised of four quadrants of highly pure semiconductor materials that included one amorphous diamond-like carbon, one C-13 diamond, and two silicon carbide (SiC). The amorphous diamond-like carbon quadrant was fractured upon impact at Utah Test and Training Range (UTTR), but the remaining three quadrants survived fully intact and all four quadrants hold an important collection of solar wind. The quadrants were removed from the target holder at NASA Johnso n Space Center Genesis Curation Laboratory in April 2005, and have been housed in stainless steel containers under continual nitrogen purge since time of disintegration. In preparation for allocation of a silicon carbide target for oxygen isotope analyses at UCLA, the two SiC targets were photographed for preliminary inspection of macro particle contamination from the hard non-nominal landing as well as characterized by spectroscopic ellipsometry to evaluate thin film contamination. This report is focused on Genesis SiC target sample number 60003.

  1. Verification of high-speed solar wind stream forecasts using operational solar wind models

    OpenAIRE

    Reiss, Martin A.; Temmer, Manuela; Veronig, Astrid M.; Nikolic, Ljubomir; Vennerstrom, Susanne; Schoengassner, Florian; Hofmeister, Stefan J.

    2016-01-01

    High-speed solar wind streams emanating from coronal holes are frequently impinging on the Earth's magnetosphere causing recurrent, medium-level geomagnetic storm activity. Modeling high-speed solar wind streams is thus an essential element of successful space weather forecasting. Here we evaluate high-speed stream forecasts made by the empirical solar wind forecast (ESWF) and the semiempirical Wang-Sheeley-Arge (WSA) model based on the in situ plasma measurements from the ACE spacecraft for ...

  2. Electrostatic Solitary Waves in the Solar Wind: Evidence for Instability at Solar Wind Current Sheets

    Science.gov (United States)

    Malaspina, David M.; Newman, David L.; Wilson, Lynn Bruce; Goetz, Keith; Kellogg, Paul J.; Kerstin, Kris

    2013-01-01

    A strong spatial association between bipolar electrostatic solitary waves (ESWs) and magnetic current sheets (CSs) in the solar wind is reported here for the first time. This association requires that the plasma instabilities (e.g., Buneman, electron two stream) which generate ESWs are preferentially localized to solar wind CSs. Distributions of CS properties (including shear angle, thickness, solar wind speed, and vector magnetic field change) are examined for differences between CSs associated with ESWs and randomly chosen CSs. Possible mechanisms for producing ESW-generating instabilities at solar wind CSs are considered, including magnetic reconnection.

  3. Verification of high-speed solar wind stream forecasts using operational solar wind models

    Science.gov (United States)

    Reiss, Martin A.; Temmer, Manuela; Veronig, Astrid M.; Nikolic, Ljubomir; Vennerstrom, Susanne; Schöngassner, Florian; Hofmeister, Stefan J.

    2016-07-01

    High-speed solar wind streams emanating from coronal holes are frequently impinging on the Earth's magnetosphere causing recurrent, medium-level geomagnetic storm activity. Modeling high-speed solar wind streams is thus an essential element of successful space weather forecasting. Here we evaluate high-speed stream forecasts made by the empirical solar wind forecast (ESWF) and the semiempirical Wang-Sheeley-Arge (WSA) model based on the in situ plasma measurements from the Advanced Composition Explorer (ACE) spacecraft for the years 2011 to 2014. While the ESWF makes use of an empirical relation between the coronal hole area observed in Solar Dynamics Observatory (SDO)/Atmospheric Imaging Assembly (AIA) images and solar wind properties at the near-Earth environment, the WSA model establishes a link between properties of the open magnetic field lines extending from the photosphere to the corona and the background solar wind conditions. We found that both solar wind models are capable of predicting the large-scale features of the observed solar wind speed (root-mean-square error, RMSE ≈100 km/s) but tend to either overestimate (ESWF) or underestimate (WSA) the number of high-speed solar wind streams (threat score, TS ≈ 0.37). The predicted high-speed streams show typical uncertainties in the arrival time of about 1 day and uncertainties in the speed of about 100 km/s. General advantages and disadvantages of the investigated solar wind models are diagnosed and outlined.

  4. Wave Modeling of the Solar Wind.

    Science.gov (United States)

    Ofman, Leon

    The acceleration and heating of the solar wind have been studied for decades using satellite observations and models. However, the exact mechanism that leads to solar wind heating and acceleration is poorly understood. In order to improve the understanding of the physical mechanisms that are involved in these processes a combination of modeling and observational analysis is required. Recent models constrained by satellite observations show that wave heating in the low-frequency (MHD), and high-frequency (ion-cyclotron) range may provide the necessary momentum and heat input to coronal plasma and produce the solar wind. This review is focused on the results of several recent solar modeling studies that include waves explicitly in the MHD and the kinetic regime. The current status of the understanding of the solar wind acceleration and heating by waves is reviewed.

  5. Ceres interaction with the solar wind

    Science.gov (United States)

    Holmstrom, Mats; Lindkvist, Jesper

    2016-10-01

    The solar wind interaction with Ceres is studied for a high water vapor release from its surface using a hybrid model including photoionization. We use a water vapor production rate thought to be due to subsurface sublimation, corresponding to a detection on 6 March 2013 by the Herschel Space Observatory. We present the general morphology of the plasma interactions, both close to Ceres and on a larger scale. Mass-loading of water ions causes a magnetic pile-up region in-front of Ceres, where the solar wind deflects and slows down. The large body makes an obstacle to the solar wind and creates an asymmetric wake downstream. On a global scale, Ceres has a comet-like interaction with the solar wind with observable perturbations far downstream of the body.

  6. Quantifying Solar Wind-Polar Cap Interactions

    Science.gov (United States)

    Urban, K. D.; Gerrard, A. J.; Lanzerotti, L. J.; Weatherwax, A. T.; Huang, Y.

    2015-12-01

    It is well known that the solar wind is a major driver of ultra-low frequency [ULF] power at ground locations from low to high latitudes. However, due to the scarcity of deep polar cap magnetometer sites, it is not clear when, where, or if this is true deep inside the polar cap on open field lines where interplanetary magnetic field [IMF] ULF waves could possibly be directly detected. Given recent observations of very large Joule heating estimates from DMSP data, together with the large heating reported by the CHAMP satellite, it is important to understand the degree to which ULF waves in the solar wind can directly cause such heating. Using a time series of lagged correlation sequences ("dynamic correlograms") between GSM Bz ULF power (computed via data obtained from NASA's Advanced Composition Explorer [ACE] ahead of Earth in the solar wind) and the horizontal ULF power (H^2=N^2+E^2) from ground-based magnetometers in Earth's southern polar cap, we investigate the direct penetration of ULF waves from the solar wind into the polar ionosphere during a gamut of space weather conditions at a distributed network of Automated Geophysical Observatories [AGOs] in Antarctica. To infer causation, a predicted lag correlation maximum at each time step is computed by simply dividing the associated distance of ACE from Earth by the concurrent bulk solar wind speed. This technique helps parse out direct penetration of solar wind ULF waves from other sources (e.g., via leakage from closed field line resonances due to the bulk solar wind plasma viscously interacting at dawn/dusk flanks inducing Kelvin-Helmholtz instabilities [KHI] or compressional modes induced by impulses in solar wind dynamic pressure). The identified direct-penetrating ULF waves are related to the DMSP-derived Poynting fluxes by regression analysis, and conclusions are drawn for the importance of the ULF source for the measured heating.

  7. The interaction of the solar wind with the interstellar medium

    Science.gov (United States)

    Axford, W. I.

    1972-01-01

    The expected characteristics of the solar wind, extrapolated from the vicinity of the earth are described. Several models are examined for the interaction of the solar wind with the interstellar plasma and magnetic field. Various aspects of the penetration of neutral interstellar gas into the solar wind are considered. The dynamic effects of the neutral gas on the solar wind are described. Problems associated with the interaction of cosmic rays with the solar wind are discussed.

  8. Solar wind tans young asteroids

    Science.gov (United States)

    2009-04-01

    A new study published in Nature this week reveals that asteroid surfaces age and redden much faster than previously thought -- in less than a million years, the blink of an eye for an asteroid. This study has finally confirmed that the solar wind is the most likely cause of very rapid space weathering in asteroids. This fundamental result will help astronomers relate the appearance of an asteroid to its actual history and identify any after effects of a catastrophic impact with another asteroid. ESO PR Photo 16a/09 Young Asteroids Look Old "Asteroids seem to get a ‘sun tan' very quickly," says lead author Pierre Vernazza. "But not, as for people, from an overdose of the Sun's ultraviolet radiation, but from the effects of its powerful wind." It has long been known that asteroid surfaces alter in appearance with time -- the observed asteroids are much redder than the interior of meteorites found on Earth [1] -- but the actual processes of this "space weathering" and the timescales involved were controversial. Thanks to observations of different families of asteroids [2] using ESO's New Technology Telescope at La Silla and the Very Large Telescope at Paranal, as well as telescopes in Spain and Hawaii, Vernazza's team have now solved the puzzle. When two asteroids collide, they create a family of fragments with "fresh" surfaces. The astronomers found that these newly exposed surfaces are quickly altered and change colour in less than a million years -- a very short time compared to the age of the Solar System. "The charged, fast moving particles in the solar wind damage the asteroid's surface at an amazing rate [3]", says Vernazza. Unlike human skin, which is damaged and aged by repeated overexposure to sunlight, it is, perhaps rather surprisingly, the first moments of exposure (on the timescale considered) -- the first million years -- that causes most of the aging in asteroids. By studying different families of asteroids, the team has also shown that an asteroid

  9. WIND observations of coherent electrostatic waves in the solar wind

    Directory of Open Access Journals (Sweden)

    A. Mangeney

    Full Text Available The time domain sampler (TDS experiment on WIND measures electric and magnetic wave forms with a sampling rate which reaches 120 000 points per second. We analyse here observations made in the solar wind near the Lagrange point L1. In the range of frequencies above the proton plasma frequency fpi and smaller than or of the order of the electron plasma frequency fpe, TDS observed three kinds of electrostatic (e.s. waves: coherent wave packets of Langmuir waves with frequencies f ~ fpe, coherent wave packets with frequencies in the ion acoustic range fpi < f < fpe, and more or less isolated non-sinusoidal spikes lasting less than 1 ms. We confirm that the observed frequency of the low frequency (LF ion acoustic wave packets is dominated by the Doppler effect: the wavelengths are short, 10 to 50 electron Debye lengths λD. The electric field in the isolated electrostatic structures (IES and in the LF wave packets is more or less aligned with the solar wind magnetic field. Across the IES, which have a spatial width of the order of ~ 25λD, there is a small but finite electric potential drop, implying an average electric field generally directed away from the Sun. The IES wave forms, which have not been previously reported in the solar wind, are similar, although with a smaller amplitude, to the weak double layers observed in the auroral regions, and to the electrostatic solitary waves observed in other regions in the magnetosphere. We have also studied the solar wind conditions which favour the occurrence of the three kinds of waves: all these e.s. waves are observed more or less continuously in the whole solar wind (except in the densest regions where a parasite prevents the TDS observations. The type (wave packet or IES of the observed LF waves is mainly determined

  10. Solar wind ion trends and signatures: STEREO PLASTIC observations approaching solar minimum

    Directory of Open Access Journals (Sweden)

    A. B. Galvin

    2009-10-01

    Full Text Available STEREO has now completed the first two years of its mission, moving from close proximity to Earth in 2006/2007 to more than 50 degrees longitudinal separation from Earth in 2009. During this time, several large-scale structures have been observed in situ. Given the prevailing solar minimum conditions, these structures have been predominantly coronal hole-associated solar wind, slow solar wind, their interfaces, and the occasional transient event. In this paper, we extend earlier solar wind composition studies into the current solar minimum using high-resolution (1-h sampling times for the charge state analysis. We examine 2-year trends for iron charge states and solar wind proton speeds, and present a case study of Carrington Rotation 2064 (December 2007 which includes minor ion (He, Fe, O kinetic and Fe composition parameters in comparison with proton and magnetic field signatures at large-scale structures observed during this interval.

  11. Scaling of Compressible Magnetohydrodynamic Turbulence in the Fast Solar Wind

    Science.gov (United States)

    Banerjee, S.; Hadid, L. Z.; Sahraoui, F.; Galtier, S.

    2016-10-01

    The role of compressible fluctuations in the energy cascade of fast solar wind turbulence is studied using a reduced form of an exact law derived recently for compressible isothermal magnetohydrodynamics and in situ observations from the THEMIS B/ARTEMIS P1 spacecraft. A statistical survey of the data revealed a turbulent energy cascade over a range of two decades of scales that is broader than the previous estimates made from an exact incompressible law. A term-by-term analysis of the compressible model reveals new insight into the role played by the compressible fluctuations in the energy cascade. The compressible fluctuations are shown to amplify by two to four times the turbulent cascade rate with respect to the incompressible model in ∼ 10 % of the analyzed samples. This new estimated cascade rate is shown to provide the adequate energy dissipation required to account for the local heating of the non-adiabatic solar wind.

  12. Dividing the Concentrator Target From the Genesis Mission

    Science.gov (United States)

    Lauer, H. V., Jr.; Burkett, P. J.; Clemett, S. J.; Gonzales, C. P.; Nakamura-Messenger, K.; Rodriquez, M. C.; See, T. H.; Sutter, B.

    2014-01-01

    The Genesis spacecraft, launched in 2001, traveled to a Lagrangian point between the Earth and Sun to collect particles from the solar wind and return them to Earth. However, during the return of the spacecraft in 2004, the parachute failed to open during descent, and the Genesis spacecraft crashed into the Utah desert. Many of the solar wind collectors were broken into smaller pieces, and the field team rapidly collected the capsule and collector pieces for later assessment. On each of the next few days, the team discovered that various collectors had survived intact, including three of four concentrator targets. Within a month, the team had imaged more than 10,000 fragments and packed them for transport to the Astromaterials Acquisition and Curation Office within the ARES Directorate at JSC. Currently, the Genesis samples are curated along with the other extraterrestrial sample collections within ARES. Although they were broken and dirty, the Genesis solar wind collectors still offered the science community the opportunity to better understand our Sun and the solar system as a whole. One of the more highly prized concentrator collectors survived the crash almost completely intact. The Genesis Concentrator was designed to concentrate the solar wind by a factor of at least 20 so that solar oxygen and nitrogen isotopes could be measured. One of these materials was the Diamond-on-Silicon (DoS) concentrator target. Unfortunately, the DoS concentrator broke on impact. Nevertheless, the scientific value of the DoS concentrator target was high. The Genesis Allocation Committee received a request for approximately 1 cm(sup 2) of the DoS specimen taken near the focal point of the concentrator for the analysis of solar wind nitrogen isotopes. The largest fragment, Genesis sample 60000, was designated for this allocation and needed to be precisely cut. The requirement was to subdivide the designated sample in a manner that prevented contamination of the sample and minimized

  13. Solar Wind Interaction With the Lunar Environment

    Science.gov (United States)

    Halekas, J. S.

    2005-12-01

    The Earth's Moon, lacking a substantial atmosphere or global magnetic field, presents one of the simpler obstacles to solar wind flow in our solar system. Despite this apparent simplicity, a rich array of interesting plasma physics occurs in the lunar environment. To first order, the Moon is completely unshielded from solar wind plasma and solar photons, and direct incidence of solar wind plasma can lead to implantation of volatiles and ion sputtering and pickup. The solar wind is blocked by the lunar obstacle, resulting in a plasma void on the night side. A potential drop across the wake boundary is generated as solar wind electrons attempt to refill the wake cavity, resulting in a tenuous high-temperature electron population and anisotropic ion beams in the wake. A system of diamagnetic currents is formed on the boundary surface, enhancing the magnetic field in the wake and reducing the field around it. Meanwhile, waves are generated by the unstable particle distributions generated by this interaction. On the day side, photon-driven positive charging of the lunar surface occurs. On the night side, on the other hand, charging is controlled by the tenuous wake plasma, and is generally electron-driven and negative. When the Moon traverses the Earth's magnetotail and is exposed to low-density plasma in the tail lobes and high-temperature plasma in the plasmasheet, extreme surface charging of up to hundreds of V positive and several keV negative can occur. Lunar surface charging may affect ion sputtering and likely results in significant dust transport. The presence of remanent crustal magnetism causes significant perturbations to this picture. Some crustal fields are large enough to stand off the solar wind (possibly affecting solar wind volatile implantation), and we observe large shock-like magnetic enhancements upstream from the largest crustal sources. The occurence of these "limb shocks" depends on solar wind parameters, suggesting that the crustal sources are

  14. Cleaning Genesis Mission Payload for Flight with Ultra-Pure Water and Assembly in ISO Class 4 Environment

    Science.gov (United States)

    Allton, Judith H.

    2012-01-01

    Genesis mission to capture and return to Earth solar wind samples had very stringent contamination control requirements in order to distinguish the solar atoms from terrestrial ones. Genesis mission goals were to measure solar composition for most of the periodic table, so great care was taken to avoid particulate contamination. Since the number 1 and 2 science goals were to determine the oxygen and nitrogen isotopic composition, organic contamination was minimized by tightly controlling offgassing. The total amount of solar material captured in two years is about 400 micrograms spread across one sq m. The contamination limit requirement for each of C, N, and O was <1015 atoms/sq cm. For carbon, this is equivalent to 10 ng/cm2. Extreme vigilance was used in pre-paring Genesis collectors and cleaning hardware for flight. Surface contamination on polished silicon wafers, measured in Genesis laboratory is approximately 10 ng/sq cm.

  15. Pluto-Charon solar wind interaction dynamics

    Science.gov (United States)

    Hale, J. P. M.; Paty, C. S.

    2017-05-01

    This work studies Charon's effects on the Pluto-solar wind interaction using a multifluid MHD model which simulates the interactions of Pluto and Charon with the solar wind as well as with each other. Specifically, it investigates the ionospheric dynamics of a two body system in which either one or both bodies possess an ionosphere. Configurations in which Charon is directly upstream and directly downstream of Pluto are considered. Depending on ionospheric and solar wind conditions, Charon could periodically pass into the solar wind flow upstream of Pluto. The results of this study demonstrate that in these circumstances Charon modifies the upstream flow, both in the case in which Charon possesses an ionosphere, and in the case in which Charon is without an ionosphere. This modification amounts to a change in the gross structure of the interaction region when Charon possesses an ionosphere but is more localized when Charon lacks an ionosphere. Furthermore, evidence is shown that supports Charon acting to partially shield Pluto from the solar wind when it is upstream of Pluto, resulting in a decrease in ionospheric loss by Pluto.

  16. Solar wind origin of terrestrial water

    CERN Document Server

    Merkl, Hans

    2011-01-01

    The origin of the Earth water reserves during the evolution of the planet is one of the big miracles in geophysics. Common explanations are storage of water in the Earth mantle at a time when the crust had not yet formed and depositing of water by comets during the time of late heavy bombardement. Both explanations have different problems - especially when comparing with the evolution of Mars and Venus. Here we discuss the possible role of hydrogen collected from the solar wind by the early Earth magnetosphere. While the water production by solar wind capture is very small today it may have been significant during the first billion years after planetary formation because solar wind was much stronger at that time and Earth magnetospheric configuration may have been different. We estimate that the contribution of solar wind hydrogen to the Earth water reserves can be up to 10% when we assume a that the Earth dipole acted as a collector and early solar wind was 1000 times stronger than today. We can not even exc...

  17. CME propagation: Where does the solar wind drag take over?

    CERN Document Server

    Sachdeva, Nishtha; Colaninno, Robin; Vourlidas, Angelos

    2015-01-01

    We investigate the Sun-Earth dynamics of a set of eight well observed solar coronal mass ejections (CMEs) using data from the STEREO spacecraft. We seek to quantify the extent to which momentum coupling between these CMEs and the ambient solar wind (i.e., the aerodynamic drag) influences their dynamics. To this end, we use results from a 3D flux rope model fit to the CME data. We find that solar wind aerodynamic drag adequately accounts for the dynamics of the fastest CME in our sample. For the relatively slower CMEs, we find that drag-based models initiated below heliocentric distances ranging from 15 to 50 $R_{\\odot}$ cannot account for the observed CME trajectories. This is at variance with the general perception that the dynamics of slow CMEs are influenced primarily by solar wind drag from a few $R_{\\odot}$ onwards. Several slow CMEs propagate at roughly constant speeds above 15--50 $R_{\\odot}$. Drag-based models initiated above these heights therefore require negligible aerodynamic drag to explain their...

  18. Complexity induced solar wind turbulence and evolution

    Science.gov (United States)

    Chang, T.

    2003-04-01

    "Complexity" has become a hot topic in nearly every field of modern physics. Solar wind plasmas are of no exception. Recently, Chang [2002], in analogy with theories developed for phenomena observed in the magnetotail and the auroral zone [Chang, 1999; 2001], demonstrated that the sporadic and localized interactions of magnetic coherent structures arising from plasma resonances could be the origin of "complexity" of nonresonant pseudo-2D spatiotemporal fluctuations in solar wind turbulence and in the coronal hole base. Such nonresonant fluctuations were shown to exist in the solar wind by Matthaeus et al. [1990] in terms of the two-dimensional correlation as a function of distance parallel and perpendicular to the mean magnetic field based on the ISEE-3 magnetometer data. Other evidences indicating the existence of such type of fluctuations in the solar wind have been reported by Tu et al. [1989], Tu and Marsch [1990, 1991], Bruno and Bavassano [1991], Bavassano and Bruno [1992], Bruno et al. [2001], and others. These results explain [Tu and Marsch, 1991] why the Alfvén ratio (a quantitative measure of Alfvénicity) is often found to be less than one in the solar wind [Belcher and Davis 1971, Solodyna et al., 1977, Bruno et al, 1985, Roberts et al., 1990], particularly for the space range farther than 0.3 AU. The above observational results are also consistent with the conclusions obtained from 2D MHD numerical simulations [Matthaeus and Larkin, 1986, Roberts and Goldstein, 1988, Goldstein et al., 1989, Roberts et al., 1991, and Roberts, 1992]. Such findings have led Chang [2002] to suggest the following evolutional scenario for the plasma turbulence in the generic fast solar wind. In and near the coronal hole base, the turbulent fluctuations are predominantly nonresonantly generated by pseudo-2D nonlinear interactions. As the fluctuations emerge from the coronal hole base, they propagate resonantly in the field-aligned direction primarily as Alfvén waves

  19. Yaglom law in the expanding solar wind

    CERN Document Server

    Gogoberidze, G; Carbone, V

    2013-01-01

    We study the Yaglom law, which relates the mixed third order structure function to the average dissipation rate of turbulence, in a uniformly expanding solar wind by using the two scales expansion model of magnetohydrodynamic (MHD) turbulence. We show that due to the expansion of the solar wind two new terms appear in the Yaglom law. The first term is related to the decay of the turbulent energy by nonlinear interactions, whereas the second term is related to the non-zero cross-correlation of the Els\\"asser fields. Using magnetic field and plasma data from WIND and Helios 2 spacecrafts, we show that at lower frequencies in the inertial range of MHD turbulence the new terms become comparable to Yaglom's third order mixed moment, and therefore they cannot be neglected in the evaluation of the energy cascade rate in the solar wind.

  20. Energy dissipation processes in solar wind turbulence

    CERN Document Server

    Wang, Y; Feng, X S; Xu, X J; Zhang, J; Sun, T R; Zuo, P B

    2015-01-01

    Turbulence is a chaotic flow regime filled by irregular flows. The dissipation of turbulence is a fundamental problem in the realm of physics. Theoretically, dissipation cannot be ultimately achieved without collisions, and so how turbulent kinetic energy is dissipated in the nearly collisionless solar wind is a challenging problem. Wave particle interactions and magnetic reconnection are two possible dissipation mechanisms, but which mechanism dominates is still a controversial topic. Here we analyze the dissipation region scaling around a solar wind magnetic reconnection region. We find that the magnetic reconnection region shows a unique multifractal scaling in the dissipation range, while the ambient solar wind turbulence reveals a monofractal dissipation process for most of the time. These results provide the first observational evidences for the intermittent multifractal dissipation region scaling around a magnetic reconnection site, and they also have significant implications for the fundamental energy...

  1. ENERGY DISSIPATION PROCESSES IN SOLAR WIND TURBULENCE

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Y.; Wei, F. S.; Feng, X. S.; Sun, T. R.; Zuo, P. B. [SIGMA Weather Group, State Key Laboratory for Space Weather, National Space Science Center, Chinese Academy of Sciences, Beijing 100190 (China); Xu, X. J. [Space Science Institute, Macau University of Science and Technology, Macao (China); Zhang, J., E-mail: yw@spaceweather.ac.cn [School of Physics, Astronomy and Computational Sciences, George Mason University, 4400 University Drive, MSN 3F3, Fairfax, Virginia 22030 (United States)

    2015-12-15

    Turbulence is a chaotic flow regime filled by irregular flows. The dissipation of turbulence is a fundamental problem in the realm of physics. Theoretically, dissipation ultimately cannot be achieved without collisions, and so how turbulent kinetic energy is dissipated in the nearly collisionless solar wind is a challenging problem. Wave particle interactions and magnetic reconnection (MR) are two possible dissipation mechanisms, but which mechanism dominates is still a controversial topic. Here we analyze the dissipation region scaling around a solar wind MR region. We find that the MR region shows unique multifractal scaling in the dissipation range, while the ambient solar wind turbulence reveals a monofractal dissipation process for most of the time. These results provide the first observational evidences for intermittent multifractal dissipation region scaling around a MR site, and they also have significant implications for the fundamental energy dissipation process.

  2. Solar wind-magnetosphere energy input functions

    Energy Technology Data Exchange (ETDEWEB)

    Bargatze, L.F.; McPherron, R.L.; Baker, D.N.

    1985-01-01

    A new formula for the solar wind-magnetosphere energy input parameter, P/sub i/, is sought by applying the constraints imposed by dimensional analysis. Applying these constraints yields a general equation for P/sub i/ which is equal to rho V/sup 3/l/sub CF//sup 2/F(M/sub A/,theta) where, rho V/sup 3/ is the solar wind kinetic energy density and l/sub CF//sup 2/ is the scale size of the magnetosphere's effective energy ''collection'' region. The function F which depends on M/sub A/, the Alfven Mach number, and on theta, the interplanetary magnetic field clock angle is included in the general equation for P/sub i/ in order to model the magnetohydrodynamic processes which are responsible for solar wind-magnetosphere energy transfer. By assuming the form of the function F, it is possible to further constrain the formula for P/sub i/. This is accomplished by using solar wind data, geomagnetic activity indices, and simple statistical methods. It is found that P/sub i/ is proportional to (rho V/sup 2/)/sup 1/6/VBG(theta) where, rho V/sup 2/ is the solar wind dynamic pressure and VBG(theta) is a rectified version of the solar wind motional electric field. Furthermore, it is found that G(theta), the gating function which modulates the energy input to the magnetosphere, is well represented by a ''leaky'' rectifier function such as sin/sup 4/(theta/2). This function allows for enhanced energy input when the interplanetary magnetic field is oriented southward. This function also allows for some energy input when the interplanetary magnetic field is oriented northward. 9 refs., 4 figs.

  3. Interplanetary shocks and solar wind extremes

    Science.gov (United States)

    Vats, Hari

    The interplanetary shocks have a very high correlation with the annual sunspot numbers during the solar cycle; however the correlation falls very low on shorter time scale. Thus poses questions and difficulty in the predictability. Space weather is largely controlled by these interplanetary shocks, solar energetic events and the extremes of solar wind. In fact most of the solar wind extremes are related to the solar energetic phenomena. It is quite well understood that the energetic events like flares, filament eruptions etc. occurring on the Sun produce high speed extremes both in terms of density and speed. There is also high speed solar wind steams associated with the coronal holes mainly because the magnetic field lines are open there and the solar plasma finds it easy to escape from there. These are relatively tenuous high speed streams and hence create low intensity geomagnetic storms of higher duration. The solar flares and/or filament eruptions usually release excess coronal mass into the interplanetary medium and thus these energetic events send out high density and high speed solar wind which statistically found to produce more intense storms. The other extremes of solar wind are those in which density and speed are much lower than the normal values. Several such events have been observed and are found to produce space weather consequences of different kind. It is found that such extremes are more common around the maximum of solar cycle 20 and 23. Most of these have significantly low Alfven Mach number. This article is intended to outline the interplanetary and geomagnetic consequences of observed by ground based and satellite systems for the solar wind extremes.

  4. Solar Wind Change Exchange from the Magnetosheath

    Science.gov (United States)

    Snowden, Steve

    2008-01-01

    We report the results of a long (approximately 100 ks) XMM-Newton observation designed to observe solar wind charge exchange emission (SWCX) from Earth's magnetosheath. By luck, the observation took place during a period of minimal solar wind flux so the SWCX emission was also minimal. Never-the-less, there is a significant if not stunning correlation between the observed O VIII count rate and our model for magnetosheath emission. We also report on the observed O VII and O VII emission.

  5. Solar Wind Earth Exchange Project (SWEEP)

    Science.gov (United States)

    2016-10-28

    AFRL-AFOSR-UK-TR-2016-0035 Solar Wind Earth Exchange Project 140200 Steven Sembay UNIVERSITY OF LEICESTER Final Report 10/28/2016 DISTRIBUTION A...To) 01 Sep 2014 to 31 Aug 2016 4. TITLE AND SUBTITLE Solar Wind Earth Exchange Project (SWEEP) 5a.  CONTRACT NUMBER 5b.  GRANT NUMBER FA9550-14-1...0200 5c.  PROGRAM ELEMENT NUMBER 61102F 6. AUTHOR(S) Steven Sembay 5d.  PROJECT NUMBER 5e.  TASK NUMBER 5f.   WORK UNIT NUMBER 7. PERFORMING

  6. Solar wind composition measurements by the Ulysses SWICS experiment during transient solar wind flows

    Science.gov (United States)

    Galvin, A. B.; Gloeckler, G.; Ipavich, F. M.; Shafer, C. M.; Geiss, J.; Ogilvie, K.

    1993-01-01

    For the March/April 1991 time period, the alpha/proton abundance ratio, the proton kinetic temperature and speed distributions, and the relative abundance of O(+7) to O(+6) is determined over each 13-minute duty cycle of the Solar Wind Ion Composition Spectrometer (SWICs) experiment on Ulysses. The ratio O(+7)/O(+6) (as a relative measure of ionization temperature) is shown to be useful in identifying possible coronal mass ejection (CME) events. We report measurements of silicon/oxygen abundance ratios and silicon and oxygen charge state distributions in the solar wind during a CME event and compare these compositions to a 'normal' solar wind time period.

  7. Magnetospheric Cavity Modes Driven by Solar Wind Dynamic Pressure Fluctuations

    CERN Document Server

    Claudepierre, S G; Elkington, S R; Lotko, W; Hudson, M K; 10.1029/2009GL039045

    2010-01-01

    We present results from Lyon-Fedder-Mobarry (LFM) global, three-dimensional magnetohydrodynamic (MHD) simulations of the solar wind-magnetosphere interaction. We use these simulations to investigate the role that solar wind dynamic pressure fluctuations play in the generation of magnetospheric ultra-low frequency (ULF) pulsations. The simulations presented in this study are driven with idealized solar wind input conditions. In four of the simulations, we introduce monochromatic ULF fluctuations in the upstream solar wind dynamic pressure. In the fifth simulation, we introduce a continuum of ULF frequencies in the upstream solar wind dynamic pressure fluctuations. In this numerical experiment, the idealized nature of the solar wind driving conditions allows us to study the magnetospheric response to only a fluctuating upstream dynamic pressure, while holding all other solar wind driving parameters constant. The simulation results suggest that ULF fluctuations in the solar wind dynamic pressure can drive magnet...

  8. Verification of high-speed solar wind stream forecasts using operational solar wind models

    DEFF Research Database (Denmark)

    Reiss, Martin A.; Temmer, Manuela; Veronig, Astrid M.

    2016-01-01

    High-speed solar wind streams emanating from coronal holes are frequently impinging on the Earth's magnetosphere causing recurrent, medium-level geomagnetic storm activity. Modeling high-speed solar wind streams is thus an essential element of successful space weather forecasting. Here we evaluate...... high-speed stream forecasts made by the empirical solar wind forecast (ESWF) and the semiempirical Wang-Sheeley-Arge (WSA) model based on the in situ plasma measurements from the Advanced Composition Explorer (ACE) spacecraft for the years 2011 to 2014. While the ESWF makes use of an empirical relation...... between the coronal hole area observed in Solar Dynamics Observatory (SDO)/Atmospheric Imaging Assembly (AIA) images and solar wind properties at the near-Earth environment, the WSA model establishes a link between properties of the open magnetic field lines extending from the photosphere to the corona...

  9. THOR Cold Solar Wind (CSW) instrument

    Science.gov (United States)

    Lavraud, Benoit

    2017-04-01

    Turbulence Heating ObserveR (THOR) is the first mission concept dedicated to the study of plasma turbulence. We present the Cold Solar Wind (CSW) instrument that is being designed for THOR. CSW will measure the full three dimensional distribution function of solar wind protons and alphas with unprecedented accuracies. It will measure solar wind proton distributions down to at least 50 ms with energy resolution of 7% and angular resolution of 1.5°. CSW is based on a top-hat electrostatic analyzer (with very large geometric factor) design with deflectors at the entrance. The particle detection system uses Channel Electron Multipliers (CEM) associated with an analog front end Application-Specific Integrated Circuit (ASIC). CSW electronics comprises a fast sweeping high voltage board, as well as an FPGA and low voltage power supply boards to perform its operations. CSW is designed to address many of the key science objectives of THOR, in particular regarding ion-scale kinetic aspects of solar wind turbulence.

  10. Geo-effectiveness of Solar Wind Extremes

    Indian Academy of Sciences (India)

    Hari Om Vats

    2006-06-01

    Examples of extreme events of solar wind and their effect on geomagnetic conditions are discussed here. It is found that there are two regimes of high speed solar wind streams with a threshold of ∼ 850 km s-1. Geomagnetic activity enhancement rate (GAER) is defined as an average increase in Ap value per unit average increase in the peak solar wind velocity (Vp) during the stream. GAER was found to be different in the two regimes of high speed streams with +ve and -ve IMF. GAER is 0.73 and 0.53 for solar wind streams with +ve and -ve IMF respectively for the extremely high speed streams (< 850 km s-1). This indicates that streams above the threshold speed with +ve IMF are 1.4 times more effective in enhancing geomagnetic activity than those with -ve IMF. However, the high speed streams below the threshold with -ve IMF are 1.1 times more effective in enhancing geomagnetic activity than those with +ve IMF. The violent solar activity period (October–November 2003) of cycle 23 presents a very special case during which many severe and strong effects were seen in the environment of the Earth and other planets; however, the z-component of IMF (Bz) is mostly positive during this period. The most severe geomagnetic storm of this cycle occurred when Bz was positive.

  11. Global Network of Slow Solar Wind

    Science.gov (United States)

    Crooker, N. U.; Antiochos, S. K.; Zhao, X.; Neugebauer, M.

    2012-01-01

    The streamer belt region surrounding the heliospheric current sheet (HCS) is generally treated as the primary or sole source of the slow solar wind. Synoptic maps of solar wind speed predicted by the Wang-Sheeley-Arge model during selected periods of solar cycle 23, however, show many areas of slow wind displaced from the streamer belt. These areas commonly have the form of an arc that is connected to the streamer belt at both ends. The arcs mark the boundaries between fields emanating from different coronal holes of the same polarity and thus trace the paths of belts of pseudostreamers, i.e., unipolar streamers that form over double arcades and lack current sheets. The arc pattern is consistent with the predicted topological mapping of the narrow open corridor or singular separator line that must connect the holes and, thus, consistent with the separatrix-web model of the slow solar wind. Near solar maximum, pseudostreamer belts stray far from the HCS-associated streamer belt and, together with it, form a global-wide web of slow wind. Recognition of pseudostreamer belts as prominent sources of slow wind provides a new template for understanding solar wind stream structure, especially near solar maximum.

  12. Solar wind and motion of dust grains

    CERN Document Server

    Klacka, J; Pastor, P; Komar, L

    2009-01-01

    Action of solar wind on arbitrarily shaped interplanetary dust particle is investigated. The final relativistically covariant equation of motion of the particle contains both orbital evolution and change of particle's mass. Non-radial solar wind velocity vector is also included. The covariant equation of motion reduces to the Poynting-Robertson effect in the limiting case when spherical particle is treated, the speed of the incident solar wind corpuscles tends to the speed of light and the corpuscles spread radially from the Sun. The results of quantum mechanics have to be incorporated into the physical considerations, in order to obtain the limiting case. The condition for the solar wind effect on motion of spherical interplanetary dust particle is $\\vec{p}'_{out}$ $=$ (1 $-$ $\\sigma'_{pr} / \\sigma'_{tot}$) $\\vec{p}'_{in}$, where $\\vec{p}'_{in}$ and $\\vec{p}'_{out}$ are incoming and outgoing radiation momenta (per unit time) measured in the proper frame of reference of the particle; $\\sigma'_{pr}$ and $\\sigm...

  13. The Solar Wind as a Turbulence Laboratory

    Directory of Open Access Journals (Sweden)

    Vincenzo Carbone

    2013-05-01

    Full Text Available In this review we will focus on a topic of fundamental importance for both astrophysics and plasma physics, namely the occurrence of large-amplitude low-frequency fluctuations of the fields that describe the plasma state. This subject will be treated within the context of the expanding solar wind and the most meaningful advances in this research field will be reported emphasizing the results obtained in the past decade or so. As a matter of fact, Helios inner heliosphere and Ulysses' high latitude observations, recent multi-spacecrafts measurements in the solar wind (Cluster four satellites and new numerical approaches to the problem, based on the dynamics of complex systems, brought new important insights which helped to better understand how turbulent fluctuations behave in the solar wind. In particular, numerical simulations within the realm of magnetohydrodynamic (MHD turbulence theory unraveled what kind of physical mechanisms are at the basis of turbulence generation and energy transfer across the spectral domain of the fluctuations. In other words, the advances reached in these past years in the investigation of solar wind turbulence now offer a rather complete picture of the phenomenological aspect of the problem to be tentatively presented in a rather organic way.

  14. Solar Wind and Motion of Meteoroids

    CERN Document Server

    Klacka, J

    1999-01-01

    The effect of nonradial component of solar wind is discussed from the qualitative point of view. It is shown that the direction of nonradial component is opposite in comparison with the direction used in papers dealing with orbital evolution of meteoroids.

  15. Decoding solar wind-magnetosphere coupling

    Science.gov (United States)

    Beharrell, M. J.; Honary, F.

    2016-10-01

    We employ a new NARMAX (Nonlinear Auto-Regressive Moving Average with eXogenous inputs) code to disentangle the time-varying relationship between the solar wind and SYM-H. The NARMAX method has previously been used to formulate a Dst model, using a preselected solar wind coupling function. In this work, which uses the higher-resolution SYM-H in place of Dst, we are able to reveal the individual components of different solar wind-magnetosphere interaction processes as they contribute to the geomagnetic disturbance. This is achieved with a graphics processing unit (GPU)-based NARMAX code that is around 10 orders of magnitude faster than previous efforts from 2005, before general-purpose programming on GPUs was possible. The algorithm includes a composite cost function, to minimize overfitting, and iterative reorthogonalization, which reduces computational errors in the most critical calculations by a factor of ˜106. The results show that negative deviations in SYM-H following a southward interplanetary magnetic field (IMF) are first a measure of the increased magnetic flux in the geomagnetic tail, observed with a delay of 20-30 min from the time the solar wind hits the bow shock. Terms with longer delays are found which represent the dipolarization of the magnetotail, the injections of particles into the ring current, and their subsequent loss by flowout through the dayside magnetopause. Our results indicate that the contribution of magnetopause currents to the storm time indices increase with solar wind electric field, E = v × B. This is in agreement with previous studies that have shown that the magnetopause is closer to the Earth when the IMF is in the tangential direction.

  16. Verification of high-speed solar wind stream forecasts using operational solar wind models

    CERN Document Server

    Reiss, Martin A; Veronig, Astrid M; Nikolic, Ljubomir; Vennerstrom, Susanne; Schoengassner, Florian; Hofmeister, Stefan J

    2016-01-01

    High-speed solar wind streams emanating from coronal holes are frequently impinging on the Earth's magnetosphere causing recurrent, medium-level geomagnetic storm activity. Modeling high-speed solar wind streams is thus an essential element of successful space weather forecasting. Here we evaluate high-speed stream forecasts made by the empirical solar wind forecast (ESWF) and the semiempirical Wang-Sheeley-Arge (WSA) model based on the in situ plasma measurements from the ACE spacecraft for the years 2011 to 2014. While the ESWF makes use of an empirical relation between the coronal hole area observed in Solar Dynamics Observatory (SDO)/Atmospheric Imaging Assembly (AIA) images and solar wind properties at the near-Earth environment, the WSA model establishes a link between properties of the open magnetic field lines extending from the photosphere to the corona and the background solar wind conditions. We found that both solar wind models are capable of predicting the large-scale features of the observed sol...

  17. Escape for the Slow Solar Wind

    Science.gov (United States)

    Kohler, Susanna

    2017-05-01

    Plasma from the Sun known as the slow solar wind has been observed far away from where scientists thought it was produced. Now new simulations may have resolved the puzzle of where the slow solar wind comes from and how it escapes the Sun to travel through our solar system.An Origin PuzzleA full view of a coronal hole (dark portion) from SDO. The edges of the coronal hole mark the boundary between open and closed magnetic field lines. [SDO; adapted from Higginson et al. 2017]The Suns atmosphere, known as the corona, is divided into two types of regions based on the behavior of magnetic field lines. In closed-field regions, the magnetic field is firmly anchored in the photosphere at both ends of field lines, so traveling plasma is confined to coronal loops and must return to the Suns surface. In open-field regions, only one end of each magnetic field line is anchored in the photosphere, so plasma is able to stream from the Suns surface out into the solar system.This second type of region known as a coronal hole is thought to be the origin of fast-moving plasma measured in our solar system and known as the fast solar wind. But we also observe a slow solar wind: plasma that moves at speeds of less than 500 km/s.The slow solar wind presents a conundrum. Its observational properties strongly suggest it originates in the hot, closed corona rather than the cooler, open regions. But if the slow solar wind plasma originates in closed-field regions of the Suns atmosphere, then how does it escape from the Sun?Slow Wind from Closed FieldsA team of scientists led by Aleida Higginson (University of Michigan) has now used high-resolution, three-dimensional magnetohydrodynamic simulations to show how the slow solar wind can be generated from plasma that starts outin closed-field parts of the Sun.A simulated heliospheric arc, composed of open magnetic field lines. [Higginson et al. 2017]Motions on the Suns surface near the boundary between open and closed-field regions the boundary

  18. The Distribution of Solar Wind Speeds During Solar Minimum: Calibration for Numerical Solar Wind Modeling Constraints on the Source of the Slow Solar Wind (Postprint)

    Science.gov (United States)

    2012-03-05

    2003) and Schwadron et al. (2005) as constraints. The new relationship was tested by using it to drive the ENLIL 3‐D MHD solar wind model and obtain...it to drive the ENLIL 3‐D MHD solar wind model and obtain solar wind parameters at Earth (1.0 AU) and Ulysses (1.4 AU). The improvements in speed...propagated out into the heliosphere using the ENLIL solar wind model . ENLIL is a 3‐D Magne- tohydrodynamic ( MHD ) model of the heliosphere [Odstrcil, 2003

  19. Genesis Ultrapure Water Megasonic Wafer Spin Cleaner

    Science.gov (United States)

    Allton, Judith H.; Stansbery, Eileen K.; Calaway, Michael J.; Rodriquez, Melissa C.

    2013-01-01

    A device removes, with high precision, the majority of surface particle contamination greater than 1-micron-diameter in size from ultrapure semiconductor wafer materials containing implanted solar wind samples returned by NASA's Genesis mission. This cleaning device uses a 1.5-liter/minute flowing stream of heated ultrapure water (UPW) with 1- MHz oscillating megasonic pulse energy focused at 3 to 5 mm away from the wafer surface spinning at 1,000 to 10,000 RPM, depending on sample size. The surface particle contamination is removed by three processes: flowing UPW, megasonic cavitations, and centripetal force from the spinning wafer. The device can also dry the wafer fragment after UPW/megasonic cleaning by continuing to spin the wafer in the cleaning chamber, which is purged with flowing ultrapure nitrogen gas at 65 psi (.448 kPa). The cleaner also uses three types of vacuum chucks that can accommodate all Genesis-flown array fragments in any dimensional shape between 3 and 100 mm in diameter. A sample vacuum chuck, and the manufactured UPW/megasonic nozzle holder, replace the human deficiencies by maintaining a consistent distance between the nozzle and wafer surface as well as allowing for longer cleaning time. The 3- to 5-mm critical distance is important for the ability to remove particles by megasonic cavitations. The increased UPW sonication time and exposure to heated UPW improve the removal of 1- to 5-micron-sized particles.

  20. Simulation of turbulent magnetic reconnection in the small-scale solar wind

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Some observational examples for the possible occurrence of the turbulent magnetic reconnection in the solar wind are found by analysing Helios spacecraft's high resolution data. The phenomena of turbulent magnetic reconnections in small scale solar wind are simulated by introducing a third order accuracy upwind compact difference scheme to the compressible two_dimensional MHD flow. Numerical results verify that the turbulent magnetic reconnection process could occur in small scale interplanetary solar wind, which is a basic feature characterizing the magnetic reconnection in high_magnetic Reynolds number (RM=2 000-10 000) solar wind. The configurations of the magnetic reconnection could evolve from a single X_line to a multiple X-line reconnection, exhibiting a complex picture of the formation, merging and evolution of magnetic islands, and finally the magnetic reconnection would evolve into a low_energy state. Its life_span of evolution is about one hour order of magnitude. Various magnetic and flow signatures are recorded in the numerical test for different evolution stages and along different crossing paths, which could in principle explain and confirm the observational samples from the Helios spacecraft. These results are helpful for revealing the basic physical processes in the solar wind turbulence.

  1. Selected solar wind parameters at 1 AU through two solar activity cycles

    Directory of Open Access Journals (Sweden)

    R. Bruno

    Full Text Available In situ measurements of the solar wind largely cover more than two solar magnetic activity cycles, namely 20 and 21. This is a very appealing opportunity to study the influence of the activity cycle on the behaviour of the solar wind parameters. As a matter of fact, many authors so far have studied this topic comparing the long-term magnetic field and plasma averages. However, when the average values are evaluated on a data sample whose duration is comparable with (or even longer than the solar rotation period we lose information about the contribution due to the fast and the slow solar wind components. Thus, discriminating in velocity plays a key role in understanding solar cycle effects on the solar wind. Based on these considerations, we performed a separate analysis for fast and slow wind, respectively. In particular, we found that: (a fast wind carries a slightly larger momentum flux density at 1 AU, probably due to dynamic stream-stream interaction; (b proton number density in slow wind is more cycle dependent than in fast wind and decreases remarkably across solar maximum; (c fast wind generally carries a magnetic field intensity stronger than that carried by the slow wind; (d we found no evidence for a positive correlation between velocity and field intensity as predicted by some theories of solar wind acceleration; (e our results would support an approximately constant divergence of field lines associated with corotating high-velocity streams.

  2. Suprathermal Solar Wind Electrons and Langmuir Turbulence

    Science.gov (United States)

    Kim, Sunjung; Yoon, Peter H.; Choe, G. S.; moon, Y.-J.

    2016-09-01

    The steady-state model recently put forth for the solar wind electron velocity distribution function during quiet time conditions, was originally composed of three population electrons (core, halo, and superhalo) with the core remaining nonresonant with any plasma waves while the halo and superhalo separately maintained steady-state resonance with whistler- and Langmuir-frequency range fluctuations, respectively. However, a recent paper demonstrates that whistler-range fluctuations in fact have no significant contribution. The present paper represents a consummation of the model in that a self-consistent model of the suprathermal electron population, which encompasses both the halo and the superhalo, is constructed solely on the basis of the Langmuir fluctuation spectrum. Numerical solutions to steady-state particle and wave kinetic equations are obtained on the basis of an initial trial electron distribution and Langmuir wave spectrum. Such a finding offers a self-consistent explanation for the observed steady-state electron distribution in the solar wind.

  3. Solar wind thermally induced magnetic fluctuations.

    Science.gov (United States)

    Navarro, R E; Moya, P S; Muñoz, V; Araneda, J A; F-Viñas, A; Valdivia, J A

    2014-06-20

    A kinetic description of Alfvén-cyclotron magnetic fluctuations for anisotropic electron-proton quasistable plasmas is studied. An analytical treatment, based on the fluctuation-dissipation theorem, consistently shows that spontaneous fluctuations in plasmas with stable distributions significantly contribute to the observed magnetic fluctuations in the solar wind, as seen, for example, in [S. D. Bale et al., Phys. Rev. Lett. 103, 211101 (2009)], even far below from the instability thresholds. Furthermore, these results, which do not require any adjustable parameters or wave excitations, are consistent with the results provided by hybrid simulations. It is expected that this analysis contributes to our understanding of the nature of magnetic fluctuations in the solar wind.

  4. Deimos: an obstacle to the solar wind.

    Science.gov (United States)

    Sauer, K; Dubinin, E; Baumgärtel, K; Bogdanov, A

    1995-08-25

    Two isolated solar wind disturbances about 5 minutes in duration were detected aboard the Russian spacecraft Phobos-2 upon its crossing the wake of the martian moon Deimos about 15,000 kilometers downstream from the moon on 1 February 1989. These plasma and magnetic events are interpreted as the inbound and outbound crossings of a Mach cone that is formed as a result of an effective interaction of the solar wind with Deimos. Possible mechanisms such as remanent magnetization, cometary type interaction caused by heavy ion or charged dust production, and unipolar induction resulting from the finite conductivity of the body are discussed. Although none of the present models is fully satisfactory, neutral gas emission through water loss by Deimos at a rate of about 10(23) molecules per second, combined with a charged dust coma, is favored.

  5. Anisotropy in solar wind plasma turbulence.

    Science.gov (United States)

    Oughton, S; Matthaeus, W H; Wan, M; Osman, K T

    2015-05-13

    A review of spectral anisotropy and variance anisotropy for solar wind fluctuations is given, with the discussion covering inertial range and dissipation range scales. For the inertial range, theory, simulations and observations are more or less in accord, in that fluctuation energy is found to be primarily in modes with quasi-perpendicular wavevectors (relative to a suitably defined mean magnetic field), and also that most of the fluctuation energy is in the vector components transverse to the mean field. Energy transfer in the parallel direction and the energy levels in the parallel components are both relatively weak. In the dissipation range, observations indicate that variance anisotropy tends to decrease towards isotropic levels as the electron gyroradius is approached; spectral anisotropy results are mixed. Evidence for and against wave interpretations and turbulence interpretations of these features will be discussed. We also present new simulation results concerning evolution of variance anisotropy for different classes of initial conditions, each with typical background solar wind parameters.

  6. Were Chondrite Parent Bodies Magnetized by the Early Solar Wind?

    Science.gov (United States)

    Oran, R.; Weiss, B. P.

    2016-12-01

    Chondrites are traditionally thought to be samples of undifferentiated bodies that never experienced large-scale melting. However, Allende and several other CV carbonaceous chondrites (Carporzen et al. 2011, Gattacceca et al., submitted) and the H chondrite Portales Valley (Bryson et al., this meeting) contain remanent magnetization acquired well after accretion. The strong intensities (tens of micro Tesla), temporal stability (lasting for several My), and late ages ( 10-100 My after solar system formation) of the magnetizations suggest they are a record of dynamos formed by a molten metallic core. This would imply that the parent bodies of these meteorites were partially differentiated, containing both melted regions and a relic chondritic crust (Abraham et al., this meeting). However, it has alternatively been proposed that CV chondrites may have been magnetized by the Interplanetary Magnetic Field (IMF) carried by the early solar wind (Tarduno et al. 2016), and which was hypothesized to be amplified at the nose of the body due to solar wind pile-up. Here we demonstrate that this scenario is unlikely, due to four main factors: 1) the magnitude of the IMF is estimated to be only 0.005 - 0.05 micro T at 1 AU for the young Sun, 2) the lack of an ionosphere and the resistivity of the crust would limit the magnetic field pile-up, 3) the time variability of the IMF in both magnitude and direction [Fig. 1A] would cuase only a fraction of the IMF to diffuse into the body [Fig. 1B], and 4) even the weak field that manages to diffuse in changes over timescales much shorter than the My timescale of magnetization acquisition and thus cannot impart a unidirectional magnetization. We demonstrate these effects quantitatively using analytical arguments, numerical simulations and analysis of solar wind in-situ measurements.

  7. Coronal Plumes in the Fast Solar Wind

    Science.gov (United States)

    Velli, Marco; Lionello, Roberto; Linker, Jon A.; Mikic, Zoran

    2011-01-01

    The expansion of a coronal hole filled with a discrete number of higher density coronal plumes is simulated using a time-dependent two-dimensional code. A solar wind model including an exponential coronal heating function and a flux of Alfven waves propagating both inside and outside the structures is taken as a basic state. Different plasma plume profiles are obtained by using different scale heights for the heating rates. Remote sensing and solar wind in situ observations are used to constrain the parameter range of the study. Time dependence due to plume ignition and disappearance is also discussed. Velocity differences of the order of approximately 50 km/s, such as those found in microstreams in the high-speed solar wind, may be easily explained by slightly different heat deposition profiles in different plumes. Statistical pressure balance in the fast wind data may be masked by the large variety of body and surface waves which the higher density filaments may carry, so the absence of pressure balance in the microstreams should not rule out their interpretation as the extension of coronal plumes into interplanetary space. Mixing of plume-interplume material via the Kelvin-Helmholtz instability seems to be possible within the parameter ranges of the models defined here, only at large di stances from the Sun, beyond 0.2-0.3 AU. Plasma and composition measurements in the inner heliosphere, such as those which will become available with Solar Orbiter and Solar Probe Plus, should therefore definitely be able to identify plume remnants in the solar wind.

  8. Origin of the Ubiquitous Fast Solar Wind

    Science.gov (United States)

    Habbal, S. R.; Woo, R.; Fineschi, S.; O'Neal, R.; Kohl, J.; Noci, G.

    1997-01-01

    The solar wind is a direct manifestation of the coronal heating processes which continue to elude us. For over three decades, observations in interplanetary space have identified two types of wind: a slow component with highly variable physical properties also characterized by speeds typically beow 500 kn/s, and a much less variable fast wind flowing on average at 750 km/s1.

  9. Genesis Concentrator Target Particle Contamination Mapping and Material Identification

    Science.gov (United States)

    Calaway, Michael J.; Rodriquez, M. C.; Allton, J. H.

    2007-01-01

    The majority of surface particles were found to be Genesis science team as well as ultra-pure water megasonic cleaning by the JSC team [4]. Removal of organic contamination from target materials is also being investigated by the science team with the use of UV-ozone cleaning devices at JSC and Open University [5]. In preparation for solar wind oxygen analyses at UCLA and Open University [1, 2], surface particle contamination on three Genesis concentrator targets was closely examined to evaluate cleaning strategies. Two silicon carbide (Genesis sample # 60001 and 60003) and one chemical vapor deposited (CVD) 13C concentrator target (60002) were imaged and mosaic mapped with optical microscopes. The resulting full target mosaic images and particle feature maps were subsequently compared with non-flight, but flight-like, concentrator targets and sample return capsule (SRC) materials. Contamination found on the flown concentrator acceleration grid was further examined using a scanning electron microscope (SEM). Energy dispersive X-ray spectroscopy (EDS) for particle identification was subsequently compared with the optical images from the flown targets. Figure 1 show that all three targets imaged in this report are fully intact and do not show any signs of material fractures. However, previous ellipsometry results and overview imaging of both flown SiC targets show a solar wind irradiation gradient from the center focal point to the outer edge [3]. In addition, due to the hard landing, each target has experienced varying degrees of impacts, scratches, and particle debris from the spacecraft and Utah impact site.

  10. Solar wind correlations: Statistical and case studies

    Science.gov (United States)

    Paularena, K. I.; Richardson, J. D.; Zastenker, G. N.; Dalin, P. A.

    1999-06-01

    Recent work on solar wind plasma correlations using data from several widely-separated spacecraft (IMP 8, INTERBALL-1, WIND, and ISEE-3) has shown that, for 6-hour periods, the average plasma correlation is ~0.7. The focus of these studies has been directed toward a statistical understanding of gross solar wind correlation behavior. In all correlations examined, lower average correlations are caused by the presence of many points from the low correlation subpopulation; nevertheless, data points from the high correlation population are still present. No single organizational factor has yet been found which adequately separates low-correlation periods from high-correlation periods. Some of the spread in correlations is due to the spatial orientations and dimensions of solar wind structures, and thus to the locational alignments of the spacecraft being correlated, but this does not adequately explain all the good or poor correlations since sometimes three nearby spacecraft show poor correlations, while sometimes three widely-separated space-craft show good correlations. Thus, in order to understand the underlying physics, detailed investigation of individual cases has been undertaken. These results will be important in assigning quality measures to space weather predictions using satellite measurements taken at L1, for example.

  11. Magnetic pumping of the solar wind

    Science.gov (United States)

    Egedal, Jan; Lichko, Emily; Daughton, William

    2015-11-01

    The transport of matter and radiation in the solar wind and terrestrial magnetosphere is a complicated problem involving competing processes of charged particles interacting with electric and magnetic fields. Given the rapid expansion of the solar wind, it would be expected that superthermal electrons originating in the corona would cool rapidly as a function of distance to the Sun. However, this is not observed, and various models have been proposed as candidates for heating the solar wind. In the compressional pumping mechanism explored by Fisk and Gloeckler particles are accelerated by random compressions by the interplanetary wave turbulence. This theory explores diffusion due to spatial non-uniformities and provides a mechanism for redistributing particle. For investigation of a related but different heating mechanism, magnetic pumping, in our work we include diffusion of anisotropic features that develops in velocity space. The mechanism allows energy to be transferred to the particles directly from the turbulence. Guided by kinetic simulations a theory is derived for magnetic pumping. At the heart of this work is a generalization of the Parker Equation to capture the role of the pressure anisotropy during the pumping process. Supported by NASA grant NNX15AJ73G.

  12. Solar Wind Charge Exchange During Geomagnetic Storms

    Science.gov (United States)

    Robertson, Ina P.; Cravens, Thomas E.; Sibeck, David G.; Collier, Michael R.; Kuntz, K. D.

    2012-01-01

    On March 31st. 2001, a coronal mass ejection pushed the subsolar magnetopause to the vicinity of geosynchronous orbit at 6.6 RE. The NASA/GSFC Community Coordinated Modeling Center (CCMe) employed a global magnetohydrodynamic (MHD) model to simulate the solar wind-magnetosphere interaction during the peak of this geomagnetic storm. Robertson et aL then modeled the expected 50ft X-ray emission due to solar wind charge exchange with geocoronal neutrals in the dayside cusp and magnetosheath. The locations of the bow shock, magnetopause and cusps were clearly evident in their simulations. Another geomagnetic storm took place on July 14, 2000 (Bastille Day). We again modeled X-ray emission due to solar wind charge exchange, but this time as observed from a moving spacecraft. This paper discusses the impact of spacecraft location on observed X-ray emission and the degree to which the locations of the bow shock and magnetopause can be detected in images.

  13. Electric solar wind sail mass budget model

    Directory of Open Access Journals (Sweden)

    P. Janhunen

    2013-02-01

    Full Text Available The electric solar wind sail (E-sail is a new type of propellantless propulsion system for Solar System transportation, which uses the natural solar wind to produce spacecraft propulsion. The E-sail consists of thin centrifugally stretched tethers that are kept charged by an onboard electron gun and, as such, experience Coulomb drag through the high-speed solar wind plasma stream. This paper discusses a mass breakdown and a performance model for an E-sail spacecraft that hosts a mission-specific payload of prescribed mass. In particular, the model is able to estimate the total spacecraft mass and its propulsive acceleration as a function of various design parameters such as the number of tethers and their length. A number of subsystem masses are calculated assuming existing or near-term E-sail technology. In light of the obtained performance estimates, an E-sail represents a promising propulsion system for a variety of transportation needs in the Solar System.

  14. Elemental building blocks of the slow solar wind

    Science.gov (United States)

    Kepko, L.; Viall, N. M.; Lepri, S. T.

    2014-12-01

    While the source of the fast solar wind is well understood to be linked to coronal holes, the source of the slow solar wind has remained elusive. A distinguishing characteristic of the slow solar wind is the high variability of the plasma parameters, such as magnetic field, velocity, density, composition, and charge state. Many previous studies of the slow solar wind have examined trends in the composition and charge states over long time scales and using data with comparatively low temporal resolution. In this study, we take advantage of high time resolution (12 min) measurements of the charge-state abundances recently reprocessed by the ACE SWICS science team to probe the timescales of solar wind variability of coherent structures at relatively small scales (<2000 Mm, or ~ 90 minutes at slow wind speeds). We use an interval of slow solar wind containing quasi pressure-balanced, periodic number density structures previously studied by Kepko et al and shown to be important in solar wind-magnetospheric coupling. The combination of high temporal resolution composition measurements and the clearly identified boundaries of the periodic structures allows us to probe the elemental slow solar wind flux tubes/structures. We use this train of 2000Mm periodic density structures as tracers of solar wind origin and/or acceleration. We find that each 2000 Mm parcel of slow solar wind, though its speed is steady, exhibits the complete range of charge state and composition variations expected for the entire range of slow solar wind, in a repeated sequence. Each parcel cycles through three states: 1) 'normal' slow wind, 2) compositionally slow wind with very high density, and 3) compositionally fast but typical slow solar wind density. We conclude by suggesting these structures form elemental building blocks of the slow solar wind, and discuss whether it is necessary to decouple separately the process(es) responsible for the release and acceleration.

  15. A statistical study of the interdependence of solar wind parameters

    Institute of Scientific and Technical Information of China (English)

    Shollykutty John; P. J. Kurian

    2009-01-01

    Correlation analysis of solar wind parameters, namely solar wind velocity, pro- ton density, proton temperature and mean interplanetary magnetic field (IMF) from the ACE spacecraft data near Earth, was done. To our best knowledge, this study is a novel one since we consider here only the parameters inside the solar wind, including the mean IMF and, hence, the solar wind is a self consistent system. We have proposed a Multiple Linear Regression (MLR) model for the prediction of the response variable (solar wind velocity) using the parameters proton density, proton temperature and mean IMF mea- sured as dally averages. About 60% of the observed value can be predicted using this model. It is shown that, in general, the correlation between solar wind parameters is sig- nificant. A deviation from the prediction at the solar maximum is interpreted. These results are verified by a graphical method.

  16. Solar Wind Associated with Near Equatorial Coronal Hole

    Indian Academy of Sciences (India)

    M. Hegde; K. M. Hiremath; Vijayakumar H. Doddamani; Shashanka R. Gurumath

    2015-09-01

    Present study probes temporal changes in the area and radiative flux of near equatorial coronal hole associated with solar wind parameters such as wind speed, density, magnetic field and temperature. Using high temporal resolution data from SDO/AIA for the two wave-lengths 193 Å and 211 Å, area and radiative flux of coronal holes are extracted and are examined for the association with high speed solar wind parameters. We find a strong association between different parameters of coronal hole and solar wind. For both the wavelength bands, we also compute coronal hole radiative energy near the earth and it is found to be of similar order as that of solar wind energy. However, for the wavelength 193 Å, owing to almost similar magnitudes of energy emitted by coronal hole and energy due to solar wind, it is conjectured that solar wind might have originated around the same height where 193 Å line is formed in the corona.

  17. Solar wind controls on Mercury's magnetospheric cusp

    Science.gov (United States)

    He, Maosheng; Vogt, Joachim; Heyner, Daniel; Zhong, Jun

    2017-04-01

    Mercury's magnetospheric cusp results from the interaction between the planetary intrinsic magnetic field and the solar wind. In this study, we assemble 2848 orbits of MESSENGER data for a comprehensive assessment of solar wind control on Mercury's cusp. We propose and validate an IMF estimation approach for the cusp transit, and construct an index to measure the magnetic disturbance. The index maximizes within the cusp, more intense than in the adjacent magnetosphere by several orders of magnitude. We develop an empirical model of the index as a function of IMFvector and Mercury's solar orbital phase. The model is used to study the cusp activity under different conditions. Comparisons reveal the cusp activity is more intense and extends further in local time, under antisunward IMF (IMFx0), under southward IMF (IMFz0), and when Mercury orbits at its perihelion than at aphelion. Besides, the cusp shifts azimuthally towards dawn when IMF reverses from westward (IMFy0), and when Mercury approaches its perihelion. The IMFx dependence is consistent with existing observations and simulations which are ascribed to the asymmetry of dayside magnetospheric configuration between sunward and anti-sunward IMF conditions. We explain the IMFy and IMFz dependences in terms of component reconnection of the magnetospheric field merging with By-dominant and Bz-dominant IMF, respectively. The control of the Mercury solar orbit phase on the intensity and local time location of the disturbance peak are possibly arising from the modulations of the heliocentric distance on the solar wind ram pressure. The existence of significant IMF dependence suggests the IMF orientation plays a role in the convection configuration at Mercury. The IMFy-dependence at Mercury is opposite to that at Earth, suggesting that component reconnection at the dayside magnetopause is more important in the Hermean system than in the terrestrial one. This also implies that reconnection occurs at lower magnetic shear

  18. Non Axi-symmetric Anisotropy of Solar Wind Turbulence

    CERN Document Server

    Turner, A J; Chapman, S C; Hnat, B; Mueller, W -C

    2011-01-01

    A key prediction of turbulence theories is frame-invariance, and in magnetohydrodynamic (MHD) turbulence, axisymmetry of fluctuations with respect to the background magnetic field. Paradoxically the power in fluctuations in the turbulent solar wind are observed to be ordered with respect to the bulk macroscopic flow as well as the background magnetic field. Here, non- axisymmetry across the inertial and dissipation ranges is quantified using in-situ observations from Cluster. The observed inertial range non- axisymmetry is reproduced by a 'fly through' sampling of a Direct Numerical Simulation of MHD turbulence. Furthermore, 'fly through' sampling of a linear superposition of transverse waves with axisymmetric fluctuations generates the trend in non- axisymmetry with power spectral exponent. The observed non-axisymmetric anisotropy may thus simply arise as a sampling effect related to Taylor's hypothesis and is not related to the plasma dynamics itself.

  19. Multifractality and intermittency in the solar wind

    Directory of Open Access Journals (Sweden)

    W. M. Macek

    2007-11-01

    Full Text Available Within the complex dynamics of the solar wind's fluctuating plasma parameters, there is a detectable, hidden order described by a chaotic strange attractor which has a multifractal structure. The multifractal spectrum has been investigated using Voyager (magnetic field data in the outer heliosphere and using Helios (plasma data in the inner heliosphere. We have also analyzed the spectrum for the solar wind attractor. The spectrum is found to be consistent with that for the multifractal measure of the self-similar one-scale weighted Cantor set with two parameters describing uniform compression and natural invariant probability measure of the attractor of the system. In order to further quantify the multifractality, we also consider a generalized weighted Cantor set with two different scales describing nonuniform compression. We investigate the resulting multifractal spectrum depending on two scaling parameters and one probability measure parameter, especially for asymmetric scaling. We hope that this generalized model will also be a useful tool for analysis of intermittent turbulence in space plasmas.

  20. Turbulent Transport in a Three-dimensional Solar Wind

    Science.gov (United States)

    Shiota, D.; Zank, G. P.; Adhikari, L.; Hunana, P.; Telloni, D.; Bruno, R.

    2017-03-01

    Turbulence in the solar wind can play essential roles in the heating of coronal and solar wind plasma and the acceleration of the solar wind and energetic particles. Turbulence sources are not well understood and thought to be partly enhanced by interaction with the large-scale inhomogeneity of the solar wind and the interplanetary magnetic field and/or transported from the solar corona. To investigate the interaction with background inhomogeneity and the turbulence sources, we have developed a new 3D MHD model that includes the transport and dissipation of turbulence using the theoretical model of Zank et al. We solve for the temporal and spatial evolution of three moments or variables, the energy in the forward and backward fluctuating modes and the residual energy and their three corresponding correlation lengths. The transport model is coupled to our 3D model of the inhomogeneous solar wind. We present results of the coupled solar wind-turbulence model assuming a simple tilted dipole magnetic configuration that mimics solar minimum conditions, together with several comparative intermediate cases. By considering eight possible solar wind and turbulence source configurations, we show that the large-scale solar wind and IMF inhomogeneity and the strength of the turbulence sources significantly affect the distribution of turbulence in the heliosphere within 6 au. We compare the predicted turbulence distribution results from a complete solar minimum model with in situ measurements made by the Helios and Ulysses spacecraft, finding that the synthetic profiles of the turbulence intensities show reasonable agreement with observations.

  1. Magnetosonic Waveguide Model of Solar Wind Flow Tubes

    Indian Academy of Sciences (India)

    A. K. Srivastava; B. N. Dwivedi

    2006-06-01

    We consider solar wind flow tubes as a magnetosonic wave-guide. Assuming a symmetric expansion in edges of slab-modelled wave-guide, we study the propagation characteristics of magnetosonic wave in the solar wind flow tubes. We present the preliminary results and discuss their implications.

  2. Wavelet Analysis on Solar Wind Parameters and Geomagnetic Indices

    CERN Document Server

    Katsavrias, Ch; Moussas, X

    2012-01-01

    The sun as an oscillator produces frequencies which propagate in the heliosphere, via solar wind, to the terrestrial magnetosphere. We searched for those frequencies in the parameters of the near Earth solar plasma and the geomagnetic indices for the past four solar cycles. The solar wind parameters used in this work are the interplanetary magnetic field, plasma beta, Alfven Mach number, solar wind speed, plasma temperature, plasma pressure, plasma density and the geomagnetic indices DST, AE, Ap and Kp. We found out that each parameter of the solar wind exhibit certain periodicities which di?erentiate in each cycle. Our results indicate intermittent periodicities in our data, some of them shared between the solar wind parameters and geomagnetic indices.

  3. Solar wind and its interaction with the magnetosphere - Measured parameters

    Energy Technology Data Exchange (ETDEWEB)

    Schwenn, R.

    1981-01-01

    The sun and the solar wind are considered in terms of the 'ballerina' model first proposed by Alfven (1977), taking into account high speed streams, the slow solar wind, stream-stream interactions, the relation of streams and magnetic structure, and transients caused by solar activity. The main features of the solar wind behavior are illustrated with the aid of data, covering one complete solar rotation in 1974/1975, which were obtained with instruments aboard the Helios-1 solar probe. It is pointed out that the solar wind acts like a huge buffer pushing onto the earth's magnetosphere with a highly variable pressure. Of the energy in the highly variable solar wind reservoir only a tiny fraction is absorbed by the magnetosphere in an obviously very nonstationary way.

  4. Solar wind and its interaction with the magnetosphere - Measured parameters

    Science.gov (United States)

    Schwenn, R.

    The sun and the solar wind are considered in terms of the 'ballerina' model first proposed by Alfven (1977), taking into account high speed streams, the slow solar wind, stream-stream interactions, the relation of streams and magnetic structure, and transients caused by solar activity. The main features of the solar wind behavior are illustrated with the aid of data, covering one complete solar rotation in 1974/1975, which were obtained with instruments aboard the Helios-1 solar probe. It is pointed out that the solar wind acts like a huge buffer pushing onto the earth's magnetosphere with a highly variable pressure. Of the energy in the highly variable solar wind reservoir only a tiny fraction is absorbed by the magnetosphere in an obviously very nonstationary way.

  5. INTERPRETING MAGNETIC VARIANCE ANISOTROPY MEASUREMENTS IN THE SOLAR WIND

    Energy Technology Data Exchange (ETDEWEB)

    TenBarge, J. M.; Klein, K. G.; Howes, G. G. [Department of Physics and Astronomy, University of Iowa, Iowa City, IA (United States); Podesta, J. J., E-mail: jason-tenbarge@uiowa.edu [Space Science Institute, Boulder, CO (United States)

    2012-07-10

    The magnetic variance anisotropy (A{sub m}) of the solar wind has been used widely as a method to identify the nature of solar wind turbulent fluctuations; however, a thorough discussion of the meaning and interpretation of the A{sub m} has not appeared in the literature. This paper explores the implications and limitations of using the A{sub m} as a method for constraining the solar wind fluctuation mode composition and presents a more informative method for interpreting spacecraft data. The paper also compares predictions of the A{sub m} from linear theory to nonlinear turbulence simulations and solar wind measurements. In both cases, linear theory compares well and suggests that the solar wind for the interval studied is dominantly Alfvenic in the inertial and dissipation ranges to scales of k{rho}{sub i} {approx_equal} 5.

  6. The Response of Auroral Electrojets to Steplike Enhancements of Energy Input from the Solar Wind

    Science.gov (United States)

    Boorstin, M.; Friel, M.; Botti, D.; Motoba, T.; Gjerloev, J. W.; Ohtani, S.

    2012-12-01

    In this study we examined the response of auroral electrojets to step-like enhancements of energy input from the solar wind to the magnetosphere. As a measure of the intensity of auroral electrojets we used SMU, SML, and SME indices, which are equivalent to the official AU, AL, and AE indices but are derived from a more global data set available through the SuperMAG international collaborative effort (http://SuperMAG.jhuapl.edu). We used the optimal solar wind coupling function proposed by Newell et al. [2007], which we calculated from propagated solar wind and IMF data measured by the ACE spacecraft. This coupling function incorporates the effects of the solar wind velocity, By, Bz, and the IMF clock angle. The best correlation between the coupling function and the SME index occurred when the coupling function was sampled at 80 minutes from the step like change and SME was sampled at 120 minutes from the step like change, for a correlation of 0.674. If we integrated the coupling function, the best correlation occurred when the coupling function was integrated up to 95 minutes from the step like change and the SME index was sampled at 110 minutes from the step like change, for a correlation of 0.664. These results imply that there is a time delay of ~30 minutes, and that although similar solar wind conditions may cause different initial developments of auroral electrojets, they generally become similar after around 2 hours and release similar total amounts of energy. We also examined pairs of events with similar time-profiles of the solar wind energy input. Although we found that auroral electrojets very often develop in similar ways, in some events significant differences can be found in both the timing and intensity of electrojet enhancements. We examined the similarities and differences of the paired events in terms of the seasons of events, but we found that the dependence on season, if at all, is very weak. Based on these results we discuss several issues in

  7. Scaling of compressible magnetohydrodynamic turbulence in the fast solar wind

    CERN Document Server

    Banerjee, Supratik; Sahraoui, Fouad; Galtier, Sebastien

    2016-01-01

    The role of compressible fluctuations in the energy cascade of fast solar wind turbulence is studied using a reduced form of an exact law derived recently (Banerjee and Galtier, PRE, 2013) for compressible isothermal magnetohydrodynamics and in-situ observations from the THEMIS B/ARTEMIS P1 spacecraft. A statistical survey of the data revealed a turbulent energy cascade over two decades of scales, which is broader than the previous estimates made from an exact incompressible law. A term-by-term analysis of the compressible model reveals new insight into the role played by the compressible fluctuations in the energy cascade. The compressible fluctuations are shown to amplify (2 to 4 times) the turbulent cascade rate with respect to the incompressible model in 10 % of the analyzed samples. This new estimated cascade rate is shown to provide the adequate energy dissipation required.

  8. Solar Wind Sputtering of Lunar Surface Materials: Role and Some Possible Implications of Potential Sputtering

    Science.gov (United States)

    Barghouty, A. F.; Adams, J. H., Jr.; Meyer, F.; Reinhold, c.

    2010-01-01

    Solar-wind induced sputtering of the lunar surface includes, in principle, both kinetic and potential sputtering. The role of the latter mechanism, however, in many focused studies has not been properly ascertained due partly to lack of data but can also be attributed to the assertion that the contribution of solar-wind heavy ions to the total sputtering is quite low due to their low number density compared to solar-wind protons. Limited laboratory measurements show marked enhancements in the sputter yields of slow-moving, highly-charged ions impacting oxides. Lunar surface sputtering yields are important as they affect, e.g., estimates of the compositional changes in the lunar surface, its erosion rate, as well as its contribution to the exosphere as well as estimates of hydrogen and water contents. Since the typical range of solar-wind ions at 1 keV/amu is comparable to the thickness of the amorphous rim found on lunar soil grains, i.e. few 10s nm, lunar simulant samples JSC-1A AGGL are specifically enhanced to have such rims in addition to the other known characteristics of the actual lunar soil particles. However, most, if not all laboratory studies of potential sputtering were carried out in single crystal targets, quite different from the rim s amorphous structure. The effect of this structural difference on the extent of potential sputtering has not, to our knowledge, been investigated to date.

  9. Kinetic and Potential Sputtering of Lunar Regolith: Contribution of Solar-Wind Heavy Ions

    Science.gov (United States)

    Meyer, F. W.; Harris, P. R.; Meyer, H. M., III; Hijiazi, H.; Barghouty, A. F.

    2013-01-01

    Sputtering of lunar regolith by protons as well as solar-wind heavy ions is considered. From preliminary measurements of H+, Ar+1, Ar+6 and Ar+9 ion sputtering of JSC-1A AGGL lunar regolith simulant at solar wind velocities, and TRIM simulations of kinetic sputtering yields, the relative contributions of kinetic and potential sputtering contributions are estimated. An 80-fold enhancement of oxygen sputtering by Ar+ over same-velocity H+, and an additional x2 increase for Ar+9 over same-velocity Ar+ was measured. This enhancement persisted to the maximum fluences investigated is approximately 1016/cm (exp2). Modeling studies including the enhanced oxygen ejection by potential sputtering due to the minority heavy ion multicharged ion solar wind component, and the kinetic sputtering contribution of all solar wind constituents, as determined from TRIM sputtering simulations, indicate an overall 35% reduction of near-surface oxygen abundance. XPS analyses of simulant samples exposed to singly and multicharged Ar ions show the characteristic signature of reduced (metallic) Fe, consistent with the preferential ejection of oxygen atoms that can occur in potential sputtering of some metal oxides.

  10. Electric solar wind sail applications overview

    CERN Document Server

    Janhunen, Pekka; Envall, Jouni; Merikallio, Sini; Montesanti, Giuditta; del Amo, Jose Gonzalez; Kvell, Urmas; Noorma, Mart; Lätt, Silver

    2014-01-01

    We analyse the potential of the electric solar wind sail for solar system space missions. Applications studied include fly-by missions to terrestrial planets (Venus, Mars and Phobos, Mercury) and asteroids, missions based on non-Keplerian orbits (orbits that can be maintained only by applying continuous propulsive force), one-way boosting to outer solar system, off-Lagrange point space weather forecasting and low-cost impactor probes for added science value to other missions. We also discuss the generic idea of data clippers (returning large volumes of high resolution scientific data from distant targets packed in memory chips) and possible exploitation of asteroid resources. Possible orbits were estimated by orbit calculations assuming circular and coplanar orbits for planets. Some particular challenge areas requiring further research work and related to some more ambitious mission scenarios are also identified and discussed.

  11. Solar cycle variations in the solar wind

    Science.gov (United States)

    Freeman, John W.; Lopez, Ramon E.

    1986-01-01

    The solar cycle variations of various solar wind parameters are reviewed. It is shown that there is a gradual decrease in the duration of high-speed streams from the declining phase of solar cycle 20 through the ascending phase of cycle 21 and a corresponding decrease in the annual average of the proton speed toward solar maximum. Beta, the ratio of the proton thermal pressure to magnetic pressure, undergoes a significant solar cycle variation, as expected from the variation in the IMF. Individual hourly averages of beta often exceed unity with 20 cases exceeding 10 and one case as high as 25. The Alfven Mach number shows a solar cycle variation similar to beta, lower aboard solar maximum. High-speed streams can be seen clearly in epsilon and the y component of the interplanetary magnetic field.

  12. Multifractal properties of solar wind turbulence: theory and observations.

    Science.gov (United States)

    Milovanov, A. V.; Avanov, L. A.; Zastenker, G. N.; Zelenyj, L. M.

    1996-10-01

    A fractal model of the solar wind is presented. This model treats fluctuations of the solar wind velocity from the viewpoint of nonlinear processes originating in the convective region and photosphere of the Sun. The multifractal structure of proton velocity fluctuations in a region of heliocentric distances from 0.2 to 0.8 AU is a result of these processes. Continuous measurements of solar wind velocity aboard the ISEE-3 spacecraft during one month were used to compare the theoretical and experimental results. It is shown that fluctuations of proton velocity have a multifractal structure in a frequency range of 10-5 - 10-3Hz.

  13. The Radial Evolution of Solar Wind Speeds (Postprint)

    Science.gov (United States)

    2012-03-05

    the equatorial region, solar wind observed above 600 km/s has rarely been accelerated from slower speeds (see Figure 3), therefore speeds greater...unlimited. ratios. This solar wind rarely has an O7+/O6+ value greater than 0.05, or a C6+/C5+ charge state ratio greater than 0.5. These maximum O7+/O6...structure and coronal sources of the solar wind during May 12th, 1997 CME, J. Atmos. Sol. Terr . Phys., 66, 1295–1309. Hefti, S., H. Grunwaldt, P

  14. Quantitative evaluation of solar wind time-shifting methods

    Science.gov (United States)

    Cameron, Taylor; Jackel, Brian

    2016-11-01

    Nine years of solar wind dynamic pressure and geosynchronous magnetic field data are used for a large-scale statistical comparison of uncertainties associated with several different algorithms for propagating solar wind measurements. The MVAB-0 scheme is best overall, performing on average a minute more accurately than a flat time-shift. We also evaluate the accuracy of these time-shifting methods as a function of solar wind magnetic field orientation. We find that all time-shifting algorithms perform significantly worse (>5 min) due to geometric effects when the solar wind magnetic field is radial (parallel or antiparallel to the Earth-Sun line). Finally, we present an empirical scheme that performs almost as well as MVAB-0 on average and slightly better than MVAB-0 for intervals with nonradial B.

  15. Chaos in the solar wind flow near Earth

    Indian Academy of Sciences (India)

    Shollykutty John; P J Kurian

    2009-04-01

    We have done a time series analysis of daily average data of solar wind velocity, density and temperature at 1 AU measured by ACE spacecraft for a period of nine years. We have used the raw data without filtering to give a faithful representation of the nonlinear behaviour of the solar wind flow which is a novel one. The sensitivity of the results on filtering is highlighted. The attractor dimension is estimated for every parameter of the solar wind and it is found that they differ substantially. Hence a chaotic picture for the problem from different angles have been obtained. The calculated Kolmogorov entropies and Lyapunov exponents are positive showing evidences that the complex solar wind near the Earth is most likely a deterministic chaotic system.

  16. Solar wind magnetic turbulence: Inferences from spectral shape

    CERN Document Server

    Treumann, R A; Narita, Y

    2016-01-01

    Some differences between theoretical, numerical and observational determinations of spectral slopes of solar wind turbulence are interpreted in the thermodynamical sense. Confirmations of turbulent Kolmogorov slopes in solar wind magnetic turbulence and magnetohydrodynamic simulations exhibit tiny differences. These are used to infer about entropy generation in the turbulent cascade and to infer about the anomalous turbulent collision frequency in the dissipative range as well as the average energy input in solar wind turbulence. Anomalous turbulent collision frequencies are obtained of the order of v < 200 Hz. The corresponding stationary solar wind magnetic energy input into magnetic turbulence in the Kolmogorov inertial range is obtained to be of the order of 50 eV/s. Its thermal fate is discussed.

  17. Accuracy Dependence of Solar Wind Timeshifting on IMF Orientation

    Science.gov (United States)

    Cameron, T. G.; Jackel, B. J.

    2016-12-01

    Nine years of solar wind dynamic pressure and geosynchronous magnetic field data are used for a large-scale statistical comparison of uncertainties associated with several different algorithms for propagating solar wind measurements. The MVAB-0 scheme used in Weimer et al. [2003] is best overall, performing on average a minute more accurately than a flat timeshift. We also evaluate the accuracy of these timeshifting methods as a function of solar wind magnetic field orientation. We find that all timeshifting algorithms perform significantly worse (> 5 minutes) when the solar wind magnetic field is radial (parallel or anti-parallel to the Earth-Sun line). Finally, we present an empirical scheme that performs almost as well as MVAB-0 on average, and slightly better than MVAB-0 for intervals with non-radial B.

  18. Pluto's interaction with the solar wind

    Energy Technology Data Exchange (ETDEWEB)

    Bagenal, F. (Univ. of Colorado, Boulder (USA)); McNutt, R.L. Jr. (Massachusetts Institute of Technology, Cambridge (USA))

    1989-11-01

    If Pluto's atmospheric escape rate is significantly greater than 1.5 x 10{sup 27} molecules s{sup {minus}1} then the interaction with the tenuous solar wind at 30 A.U. will be like that of a comet: there will be extensive ion pick-up upstream and the size of the interaction region will vary directly with variations in the solar wind flux. If the escape flux is much less, then one expects that the solar wind will be deflected around Pluto's ionosphere in a Venus-like interaction. In either case, the weak interplanetary magnetic field at 30 A.U. results in very large gyroradii for the picked up ions and a thick bow shock, necessitating a kinetic treatment of the interaction. Strong variations in the size of the interaction region are expected on time scales of days due to changes in the solar wind.

  19. Solar wind stream structure at large heliocentric distances Pioneer observations

    Science.gov (United States)

    Gazis, P. R.

    1987-01-01

    Time profiles and histograms of plasma data from Pioneers 10 and 11 are examined for the period between 1975 and 1983. During this time, Pioneer 10 traveled between a heliocentric distance of 8.7 and 30.4 AU. The velocity structure of the solar wind at these heliocentric distances is found to have one of two distinct forms: approximately 70 percent of the time the solar wind has a nearly flat velocity profile. Occasionally, this flat velocity profile is accompanied by quasi-periodic variations in density and in thermal speed consistent with the concept that the 'corotating interaction regions' which are produced by the interaction of high- and low-speed streams at intermediate heliocentric distances are replaced by 'pressure regions' in the outer heliosphere. The remaining 30 percent of the time the solar wind is marked by large (50-200 km/s) long-term (30-120 days) shifts in the average solar wind velocity.

  20. The structure of the solar wind in the inner heliosphere

    Science.gov (United States)

    Lee, Christina On-Yee

    2010-12-01

    This dissertation is devoted to expanding our understanding of the solar wind structure in the inner heliosphere and variations therein with solar activity. Using spacecraft observations and numerical models, the origins of the large-scale structures and long-term trends of the solar wind are explored in order to gain insights on how our Sun determines the space environments of the terrestrial planets. I use long term measurements of the solar wind density, velocity, interplanetary magnetic field, and particles, together with models based on solar magnetic field data, to generate time series of these properties that span one solar rotation (˜27 days). From these time series, I assemble and obtain the synoptic overviews of the solar wind properties. The resulting synoptic overviews show that the solar wind around Mercury, Venus, Earth, and Mars is a complex co-rotating structure with recurring features and occasional transients. During quiet solar conditions, the heliospheric current sheet, which separates the positive interplanetary magnetic field from the negative, usually has a remarkably steady two- or four-sector structure that persists for many solar rotations. Within the sector boundaries are the slow and fast speed solar wind streams that originate from the open coronal magnetic field sources that map to the ecliptic. At the sector boundaries, compressed high-density and the related high-dynamic pressure ridges form where streams from different coronal source regions interact. High fluxes of energetic particles also occur at the boundaries, and are seen most prominently during the quiet solar period. The existence of these recurring features depends on how long-lived are their source regions. In the last decade, 3D numerical solar wind models have become more widely available. They provide important scientific tools for obtaining a more global view of the inner heliosphere and of the relationships between conditions at Mercury, Venus, Earth, and Mars. When

  1. Analysis of ISEE-3/ICE solar wind data

    Science.gov (United States)

    Coplan, Michael A.

    1989-01-01

    Under the grant that ended November 11, 1988 work was accomplished in a number of areas, as follows: (1) Analysis of solar wind data; (2) Analysis of Giacobini/Zinner encounter data; (3) Investigation of solar wind and magnetospheric electron velocity distributions; and (4) Experimental investigation of the electronic structure of clusters. Reprints and preprints of publications resulting from this work are included in the appendices.

  2. On Electron-scale Whistler Turbulence in the Solar Wind

    Science.gov (United States)

    Narita, Y.; Nakamura, R.; Baumjohann, W.; Glassmeier, K.-H.; Motschmann, U.; Giles, B.; Magnes, W.; Fischer, D.; Torbert, R. B.; Russell, C. T.; Strangeway, R. J.; Burch, J. L.; Nariyuki, Y.; Saito, S.; Gary, S. P.

    2016-08-01

    For the first time, the dispersion relation for turbulence magnetic field fluctuations in the solar wind is determined directly on small scales of the order of the electron inertial length, using four-point magnetometer observations from the Magnetospheric Multiscale mission. The data are analyzed using the high-resolution adaptive wave telescope technique. Small-scale solar wind turbulence is primarily composed of highly obliquely propagating waves, with dispersion consistent with that of the whistler mode.

  3. Equatorwards Expansion of Unperturbed, High-Latitude Fast Solar Wind

    CERN Document Server

    Dorrian, Gareth; Fallows, Richard; Bisi, Mario

    2012-01-01

    We use dual-site radio observations of interplanetary scintillation (IPS) with extremely long baselines (ELB) to examine meridional flow characteristics of the ambient fast solar wind at plane-of-sky heliocentric distances of 24-85 solar radii (R\\odot). Our results demonstrate an equatorwards deviation of 3-4{\\deg} in the bulk fast solar wind flow direction over both northern and southern solar hemispheres during different times in the declining phase of Solar Cycle 23.

  4. Modulation of the Solar Wind Velocity by Mercury

    CERN Document Server

    Nikulin, Igor F

    2013-01-01

    To study the variations in the solar wind velocity during inferior conjunctions of Mercury and Earth, we analyzed 54 events in the period 1995 to 2012 by the superimposed epoch method. We have found a noticeable increase in the velocity both before and after the conjunctions as well as decrease in the velocity within 3-4 days after them, which seems to be associated with Mercury's "shadow". The results obtained might be used to improve a forecast of the solar wind velocity.

  5. Predicted Impacts of Proton Temperature Anisotropy on Solar Wind Turbulence

    OpenAIRE

    Klein, Kristopher G; Howes, Gregory G.

    2015-01-01

    Particle velocity distributions measured in the weakly collisional solar wind are frequently found to be non-Maxwellian, but how these non-Maxwellian distributions impact the physics of plasma turbulence in the solar wind remains unanswered. Using numerical solutions of the linear dispersion relation for a collisionless plasma with a bi-Maxwellian proton velocity distribution, we present a unified framework for the four proton temperature anisotropy instabilities, identifying the associated s...

  6. Residual Energy Spectrum of Solar Wind Turbulence

    CERN Document Server

    Chen, C H K; Salem, C S; Maruca, B A

    2013-01-01

    It has long been known that the energy in velocity and magnetic field fluctuations in the solar wind is not in equipartition. In this paper, we present an analysis of 5 years of Wind data at 1 AU to investigate the reason for this. The residual energy (difference between energy in velocity and magnetic field fluctuations) was calculated using both the standard magnetohydrodynamic (MHD) normalization for the magnetic field and a kinetic version, which includes temperature anisotropies and drifts between particle species. It was found that with the kinetic normalization, the fluctuations are closer to equipartition, with a mean normalized residual energy of sigma_r = -0.19 and mean Alfven ratio of r_A = 0.71. The spectrum of residual energy, in the kinetic normalization, was found to be steeper than both the velocity and magnetic field spectra, consistent with some recent MHD turbulence predictions and numerical simulations, having a spectral index close to -1.9. The local properties of residual energy and cros...

  7. Topological Origins of the Slow Solar Wind

    Science.gov (United States)

    Antiochos, S.

    2008-12-01

    Although the slow solar wind has been studied for decades with both in situ and remote sensing observations, its origin is still a matter of intense debate. In the standard quasi-steady model, the slow wind is postulated to originate near coronal hole boundaries that define topologically well-behaved separatrices between open and closed field regions. In the interchange model, on the other hand, the slow wind is postulated to originate on open flux that is dynamically diffusing throughout the seemingly closed-field corona. We argue in favor of the quasi-steady scenario and propose that the slow wind is due to two effects: First, the open-closed boundary is highly complex due to the complexity of the photospheric flux distribution. Second, this boundary is continuously driven by the transport of magnetic helicity from the closed field region into the open. The implications of this model for the structure and dynamics of the corona and slow wind are discussed, and observational tests of the model are presented. This work has been supported, in part, by the NASA LWS, HTP, and SR&T programs.

  8. Comparative Study of MHD Modeling of the Background Solar Wind

    CERN Document Server

    Gressl, C; Temmer, M; Odstrcil, D; Linker, J A; Mikic, Z; Riley, P

    2013-01-01

    Knowledge about the background solar wind plays a crucial role in the framework of space weather forecasting. In-situ measurements of the background solar wind are only available for a few points in the heliosphere where spacecraft are located, therefore we have to rely on heliospheric models to derive the distribution of solar wind parameters in interplanetary space. We test the performance of different solar wind models, namely Magnetohydrodynamic Algorithm outside a Sphere/ENLIL (MAS/ENLIL), Wang-Sheeley-Arge/ENLIL (WSA/ENLIL), and MAS/MAS, by comparing model results with in-situ measurements from spacecraft located at 1 AU distance to the Sun (ACE, Wind). To exclude the influence of interplanetary coronal mass ejections (ICMEs), we chose the year 2007 as a time period with low solar activity for our comparison. We found that the general structure of the background solar wind is well reproduced by all models. The best model results were obtained for the parameter solar wind speed. However, the predicted ar...

  9. Anisotropy of solar wind fluctuations: fast wind vs slow wind.

    Science.gov (United States)

    Dasso, S.; Milano, L. J.; Matthaeus, W. H.; Smith, C. W.

    2004-12-01

    The fluctuations in the solar wind are often modeled in terms of two distinct populations: (a) a 'wave-like' population with quasi-parallel wavenumbers and (b) a quasi-two dimensional 'turbulent-like' fluctuations with perpendicular wavenumbers. Here the qualification "quasi-parallel" or "quasi-2D" means that nearby wavevectors are grouped together in an idealzed way, for simplicity. The relative abundance of these two populations is important in gaining insight on the dynamics of waves or turbulence in the solar wind, and also in understanding the transport of energetic particle populations, as turbulence geometry has a major impact on scattering. It has been established in the literature that turbulence is, generally speaking, more developed in the slow solar wind, with power spectra closer to the kolmogorov value at 1AU, while the fast solar wind is more "Alfvenic", typically with higher values of the cross helicity. It seems natural therefore to investigate the anisotropy structure of solar wind fluctuations as a function of wind speed. We present here our preliminary results in this regard, obtained from magnetic and plasma data from the ACE specraft, at 1AU, essentially in the ecliptic plane. We also discuss possible implications for the modeling the evolution of waves and turbulence in the solar wind.

  10. Clean Assembly of Genesis Collector Canister for Flight: Lessons for Planetary Sample Return

    Science.gov (United States)

    Allton, J. H.; Stansbery, E. K.; Allen, C. C.; Warren, J. L.; Schwartz, C. M.

    2007-01-01

    Measurement of solar composition in the Genesis collectors requires not only high sensitivity but very low blanks; thus, very strict collector contamination minimization was required beginning with mission planning and continuing through hardware design, fabrication, assembly and testing. Genesis started with clean collectors and kept them clean inside of a canister. The mounting hardware and container for the clean collectors were designed to be cleanable, with access to all surfaces for cleaning. Major structural components were made of aluminum and cleaned with megasonically energized ultrapure water (UPW). The UPW purity was >18 M resistivity. Although aluminum is relatively difficult to clean, the Genesis protocol achieved level 25 and level 50 cleanliness on large structural parts; however, the experience suggests that surface treatments may be helpful on future missions. All cleaning was performed in an ISO Class 4 (Class 10) cleanroom immediately adjacent to an ISO Class 4 assembly room; thus, no plastic packaging was required for transport. Persons assembling the canister were totally enclosed in cleanroom suits with face shield and HEPA filter exhaust from suit. Interior canister materials, including fasteners, were installed, untouched by gloves, using tweezers and other stainless steel tools. Sealants/lubricants were not exposed inside the canister, but vented to the exterior and applied in extremely small amounts using special tools. The canister was closed in ISO Class 4, not to be opened until on station at Earth-Sun L1. Throughout the cleaning and assembly, coupons of reference materials that were cleaned at the same time as the flight hardware were archived for future reference and blanks. Likewise reference collectors were archived. Post-mission analysis of collectors has made use of these archived reference materials.

  11. Simulation study of solar wind push on a charged wire: basis of solar wind electric sail propulsion

    Directory of Open Access Journals (Sweden)

    P. Janhunen

    2007-03-01

    Full Text Available One possibility for propellantless propulsion in space is to use the momentum flux of the solar wind. A way to set up a solar wind sail is to have a set of thin long wires which are kept at high positive potential by an onboard electron gun so that the wires repel and deflect incident solar wind protons. The efficiency of this so-called electric sail depends on how large force a given solar wind exerts on a wire segment and how large electron current the wire segment draws from the solar wind plasma when kept at a given potential. We use 1-D and 2-D electrostatic plasma simulations to calculate the force and present a semitheoretical formula which captures the simulation results. We find that under average solar wind conditions at 1 AU the force per unit length is (5±1×10−8 N/m for 15 kV potential and that the electron current is accurately given by the well-known orbital motion limited (OML theory cylindrical Langmuir probe formula. Although the force may appear small, an analysis shows that because of the very low weight of a thin wire per unit length, quite high final speeds (over 50 km/s could be achieved by an electric sailing spacecraft using today's flight-proved components. It is possible that artificial electron heating of the plasma in the interaction region could increase the propulsive effect even further.

  12. Generalized Thermostatistics and Wavelet Analysis of the Solar Wind and Proton Density Variability

    CERN Document Server

    Bolzan, M J A; Ramos, F M; Fagundes, P R; Sahai, Y; Bolzan, Mauricio J. A.; Rosa, Reinaldo R.; Ramos, Fernando M.; Fagundes, Paulo R.; Sahai, Yogeshwar

    2005-01-01

    In this paper, we analyze the probability density function (PDF) of solar wind velocity and proton density, based on generalized thermostatistics (GT) approach, comparing theoretical results with observational data. The time series analyzed were obtained from the SOHO satellite mission where measurements were sampled every hour. We present in the investigations data for two years of different solar activity: (a) moderate activity (MA) period (1997) and (b) high activity (HA) period (2000). For the MA period, the results show good agreement between experimental data and GT model. For the HA period, the agreement between experimental and theoretical PDFs was fairly good, but some distortions were observed, probably due to intermittent characteristics of turbulent processes. As a complementary analysis, the Global Wavelet Spectrum (GWS) was obtained allowing the characterization of the predominant temporal variability scales for both the periods and the stochastics aspects of the nonlinear solar wind variability...

  13. The magnetosphere under weak solar wind forcing

    Directory of Open Access Journals (Sweden)

    C. J. Farrugia

    2007-02-01

    Full Text Available The Earth's magnetosphere was very strongly disturbed during the passage of the strong shock and the following interacting ejecta on 21–25 October 2001. These disturbances included two intense storms (Dst*≈−250 and −180 nT, respectively. The cessation of this activity at the start of 24 October ushered in a peculiar state of the magnetosphere which lasted for about 28 h and which we discuss in this paper. The interplanetary field was dominated by the sunward component [B=(4.29±0.77, −0.30±0.71, 0.49±0.45 nT]. We analyze global indicators of geomagnetic disturbances, polar cap precipitation, ground magnetometer records, and ionospheric convection as obtained from SuperDARN radars. The state of the magnetosphere is characterized by the following features: (i generally weak and patchy (in time low-latitude dayside reconnection or reconnection poleward of the cusps; (ii absence of substorms; (iii a monotonic recovery from the previous storm activity (Dst corrected for magnetopause currents decreasing from ~−65 to ~−35 nT, giving an unforced decreased of ~1.1 nT/h; (iv the probable absence of viscous-type interaction originating from the Kelvin-Helmholtz (KH instability; (v a cross-polar cap potential of just 20–30 kV; (vi a persistent, polar cap region containing (vii very weak, and sometimes absent, electron precipitation and no systematic inter-hemisphere asymmetry. Whereas we therefore infer the presence of a moderate amount of open flux, the convection is generally weak and patchy, which we ascribe to the lack of solar wind driver. This magnetospheric state approaches that predicted by Cowley and Lockwood (1992 but has never yet been observed.

  14. A survey of solar wind conditions at 5 AU: A tool for interpreting solar wind-magnetosphere interactions at Jupiter

    Directory of Open Access Journals (Sweden)

    Robert Wilkes Ebert

    2014-09-01

    Full Text Available We examine Ulysses solar wind and interplanetary magnetic field (IMF observations at 5 AU for two ~13 month intervals during the rising and declining phases of solar cycle 23 and the predicted response of the Jovian magnetosphere during these times. The declining phase solar wind, composed primarily of corotating interaction regions and high-speed streams, was, on average, faster, hotter, less dense, and more Alfvénic relative to the rising phase solar wind, composed mainly of slow wind and interplanetary coronal mass ejections. Interestingly, none of solar wind and IMF distributions reported here were bimodal, a feature used to explain the bimodal distribution of bow shock and magnetopause standoff distances observed at Jupiter. Instead, many of these distributions had extended, non-Gaussian tails that resulted in large standard deviations and much larger mean over median values. The distribution of predicted Jupiter bow shock and magnetopause standoff distances during these intervals were also not bimodal, the mean/median values being larger during the declining phase by ~1 – 4%. These results provide data-derived solar wind and IMF boundary conditions at 5 AU for models aimed at studying solar wind-magnetosphere interactions at Jupiter and can support the science investigations of upcoming Jupiter system missions. Here, we provide expectations for Juno, which is scheduled to arrive at Jupiter in July 2016. Accounting for the long-term decline in solar wind dynamic pressure reported by McComas et al. (2013, Jupiter’s bow shock and magnetopause is expected to be at least 8 – 12% further from Jupiter, if these trends continue.

  15. Direct evidence for kinetic effects associated with solar wind reconnection.

    Science.gov (United States)

    Xu, Xiaojun; Wang, Yi; Wei, Fengsi; Feng, Xueshang; Deng, Xiaohua; Ma, Yonghui; Zhou, Meng; Pang, Ye; Wong, Hon-Cheng

    2015-01-28

    Kinetic effects resulting from the two-fluid physics play a crucial role in the fast collisionless reconnection, which is a process to explosively release massive energy stored in magnetic fields in space and astrophysical plasmas. In-situ observations in the Earth's magnetosphere provide solid consistence with theoretical models on the point that kinetic effects are required in the collisionless reconnection. However, all the observations associated with solar wind reconnection have been analyzed in the context of magnetohydrodynamics (MHD) although a lot of solar wind reconnection exhausts have been reported. Because of the absence of kinetic effects and substantial heating, whether the reconnections are still ongoing when they are detected in the solar wind remains unknown. Here, by dual-spacecraft observations, we report a solar wind reconnection with clear Hall magnetic fields. Its corresponding Alfvenic electron outflow jet, derived from the decouple between ions and electrons, is identified, showing direct evidence for kinetic effects that dominate the collisionless reconnection. The turbulence associated with the exhaust is a kind of background solar wind turbulence, implying that the reconnection generated turbulence has not much developed.

  16. Slow Solar Wind from S-Web Arcs

    Science.gov (United States)

    Higginson, Aleida K.; Antiochos, Spiro K.; DeVore, C. Richard; Wyper, Peter; Zurbuchen, Thomas H.

    2017-08-01

    A long-standing mystery posed by in-situ heliospheric observations is the large angular extent of slow solar wind about the heliospheric current sheet (HCS). Measurements of plasma composition strongly imply that much of the slow wind consists of plasma from the closed corona that escapes onto open field lines, presumably by field-line opening or by interchange reconnection. Both of these processes are expected to release closed-field plasma into the solar wind within and immediately adjacent to the HCS. The recently proposed Separatrix-Web (S-Web) Theory postulates that the observations of slow wind far from the HCS can be explained by the dynamical interaction of open and closed flux in regions of complex coronal-hole topology. We present the first high-resolution, three-dimensional numerical simulations of the dynamic S-Web. These simulations suggest that photospheric motions at coronal-hole boundaries are responsible for the release of slow solar wind plasma from the magnetically closed solar corona, specifically through prolific interchange magnetic reconnection. The location of this plasma once it is released into the solar wind depends strongly on the geometry of the coronal-hole flux. We demonstrate how the dynamics at the boundaries of narrow corridors of open flux (coronal hole corridors) can create giant S-Web arcs of slow solar wind at high latitudes in the heliosphere, far from the HCS, accounting for the long-puzzling slow-wind observations.

  17. Relationship Between Solar Wind Speed and Coronal Magnetic Field Properties

    CERN Document Server

    Fujiki, Ken'ichi; Iju, Tomoya; Hakamada, Kazuyuki; Kojima, Masayoshi

    2015-01-01

    We have studied the relationship between the solar-wind speed $[V]$ and the coronal magnetic-field properties (a flux expansion factor [$f$] and photospheric magnetic-field strength [$B_{\\mathrm{S}}$]) at all latitudes using data of interplanetary scintillation and solar magnetic field obtained for 24 years from 1986 to 2009. Using a cross-correlation analyses, we verified that $V$ is inversely proportional to $f$ and found that $V$ tends to increase with $B_{\\mathrm{S}}$ if $f$ is the same. As a consequence, we find that $V$ has extremely good linear correlation with $B_{\\mathrm{S}}/f$. However, this linear relation of $V$ and $B_{\\mathrm{S}}/f$ cannot be used for predicting the solar-wind velocity without information on the solar-wind mass flux. We discuss why the inverse relation between $V$ and $f$ has been successfully used for solar-wind velocity prediction, even though it does not explicitly include the mass flux and magnetic-field strength, which are important physical parameters for solar-wind accele...

  18. On Solar Wind Origin and Acceleration: Measurements from ACE

    Science.gov (United States)

    Stakhiv, Mark; Lepri, Susan T.; Landi, Enrico; Tracy, Patrick; Zurbuchen, Thomas H.

    2016-10-01

    The origin and acceleration of the solar wind are still debated. In this paper, we search for signatures of the source region and acceleration mechanism of the solar wind in the plasma properties measured in situ by the Advanced Composition Explorer spacecraft. Using the elemental abundances as a proxy for the source region and the differential velocity and ion temperature ratios as a proxy for the acceleration mechanism, we are able to identify signatures pointing toward possible source regions and acceleration mechanisms. We find that the fast solar wind in the ecliptic plane is the same as that observed from the polar regions and is consistent with wave acceleration and coronal-hole origin. We also find that the slow wind is composed of two components: one similar to the fast solar wind (with slower velocity) and the other likely originating from closed magnetic loops. Both components of the slow solar wind show signatures of wave acceleration. From these findings, we draw a scenario that envisions two types of wind, with different source regions and release mechanisms, but the same wave acceleration mechanism.

  19. Poynting-Robertson drag and solar wind in the space debris problem

    CERN Document Server

    Lhotka, Christoph; Gales, Catalin

    2016-01-01

    We analyze the combined effect of Poynting-Robertson and solar wind drag on space debris. We derive a model within Cartesian, Gaussian and Hamiltonian frameworks. We focus on the geosynchronous resonance, although the results can be easily generalized to any resonance. By numerical and analytical techniques, we compute the drift in semi-major axis due to Poynting-Robertson and solar wind drag. After a linear stability analysis of the equilibria, we combine a careful investigation of the regular, resonant, chaotic behavior of the phase space with a long-term propagation of a sample of initial conditions. The results strongly depend on the value of the area-to-mass ratio of the debris, which might show different dynamical behaviors: temporary capture or escape from the geosynchronous resonance, as well as temporary capture or escape from secondary resonances involving the rate of variation of the longitude of the Sun. Such analysis shows that Poynting-Robertson and solar wind drag must be taken into account, wh...

  20. A multiple flux-tube solar wind model

    CERN Document Server

    Pinto, Rui F

    2016-01-01

    We present a new model, MULTI-VP, that computes the three-dimensional structure of the solar wind which includes the chromosphere, the transition region, and the corona and low heliosphere. MULTI- VP calculates a large ensemble of wind profiles flowing along open magnetic field-lines which sample the whole three-dimensional atmosphere or, alternatively, on a given region of interest. The radial domain starts from the photosphere and extends, typically, to about 30 $R_{sun}$ . The elementary uni-dimensional wind solutions are based on a mature numerical scheme which was adapted in order to accept any flux-tube geometry. We discuss here the first results obtained with this model. We use Potential Field Source-Surface (PFSS) extrapolations of magnetograms from the Wilcox Solar Observatory (WSO) to determine the structure of the background magnetic field. Our results support the hypothesis that the geometry of the magnetic flux-tubes in the lower corona controls the distribution of slow and fast wind flows. The i...

  1. Firehose constraints for the solar wind suprathermal electrons

    CERN Document Server

    Lazar, M; Poedts, S; Štverák, Š

    2016-01-01

    The indefinite increase of temperature predicted by the solar wind expansion in the direction parallel to the interplanetary magnetic field is already notorious for not being confirmed by the observations. In hot and dilute plasmas from space particle-particle collisions are not efficient in constraining large deviations from isotropy, but the resulting firehose instability provides in this case plausible limitations for the temperature anisotropy of the thermal (core) populations of both the electron and proton species. The present paper takes into discussion the suprathermal (halo) electrons, which are ubiquitous in the solar wind. Less dense but hotter than the core, suprathermals may be highly anisotropic and susceptible to the firehose instability. The main features of the instability are here derived from a first-order theory for conditions specific to the suprathermal electrons in the solar wind and terrestrial magnetospheres. Unveiled here, new regimes of the electron firehose instability may be exclu...

  2. Solar Wind Turbulence and the Role of Ion Instabilities

    CERN Document Server

    Alexandrova, Olga; Sorriso-Valvo, Luca; Horbury, Timothy S; Bale, Stuart D

    2013-01-01

    Solar wind is probably the best laboratory to study turbulence in astrophysical plasmas. In addition to the presence of magnetic field, the differences with neutral fluid isotropic turbulence are: weakness of collisional dissipation and presence of several characteristic space and time scales. In this paper we discuss observational properties of solar wind turbulence in a large range from the MHD to the electron scales. At MHD scales, within the inertial range, turbulence cascade of magnetic fluctuations develops mostly in the plane perpendicular to the mean field. Solar wind turbulence is compressible in nature. The spectrum of velocity fluctuations do not follow magnetic field one. Probability distribution functions of different plasma parameters are not Gaussian, indicating presence of intermittency. At the moment there is no global model taking into account all these observed properties of the inertial range. At ion scales, turbulent spectra have a break, compressibility increases and the density fluctuat...

  3. The Character of the Solar Wind, Surface Interactions, and Water

    Science.gov (United States)

    Farrell, William M.

    2011-01-01

    We discuss the key characteristics of the proton-rich solar wind and describe how it may interact with the lunar surface. We suggest that solar wind can be both a source and loss of water/OH related volatiles, and review models showing both possibilities. Energy from the Sun in the form of radiation and solar wind plasma are in constant interaction with the lunar surface. As such, there is a solar-lunar energy connection, where solar energy and matter are continually bombarding the lunar surface, acting at the largest scale to erode the surface at 0.2 Angstroms per year via ion sputtering [1]. Figure 1 illustrates this dynamically Sun-Moon system.

  4. Stationarity of extreme bursts in the solar wind.

    Science.gov (United States)

    Moloney, N R; Davidsen, J

    2014-05-01

    Recent results have suggested that the statistics of bursts in the solar wind vary with solar cycle. Here, we show that this variation is basically absent if one considers extreme bursts. These are defined as threshold-exceeding events over the range of high thresholds for which their number decays as a power law. In particular, we find that the distribution of duration times and energies of extreme bursts in the solar wind ε parameter and similar observables are independent of the solar cycle and in this sense stationary, and show robust asymptotic power laws with exponents that are independent of the specific threshold. This is consistent with what has been observed for solar flares and, thus, provides evidence in favor of a link between solar flares and extreme bursts in the solar wind.

  5. Intermittency and local heating in the solar wind.

    Science.gov (United States)

    Osman, K T; Matthaeus, W H; Wan, M; Rappazzo, A F

    2012-06-29

    Evidence for nonuniform heating in the solar wind plasma near current sheets dynamically generated by magnetohydrodynamic (MHD) turbulence is obtained using measurements from the ACE spacecraft. These coherent structures only constitute 19% of the data, but contribute 50% of the total plasma internal energy. Intermittent heating manifests as elevations in proton temperature near current sheets, resulting in regional heating and temperature enhancements extending over several hours. The number density of non-Gaussian structures is found to be proportional to the mean proton temperature and solar wind speed. These results suggest magnetofluid turbulence drives intermittent dissipation through a hierarchy of coherent structures, which collectively could be a significant source of coronal and solar wind heating.

  6. Mechanism of proton anisotropic velocity distribution in the solar wind

    Institute of Scientific and Technical Information of China (English)

    AO; Xianzhi(敖先志); SHEN; Ji(沈迹); TU; Chuanyi(涂传诒)

    2003-01-01

    Although it has been long that spacecraft observed the anisotropy of velocity protons in the solar wind, there is still not a reasonable explanation. In this paper we try to give an explanation from the diffusion plateau of protoncyclotron resonance predicted by the quasi-linear theory for the resonance between the protons and the parallel propagating waves. We consider the effect of dispersion relation on diffusion plateau and notice that the diffusion plateau we have got by using cold plasma dispersion relation accords with the density contours in the velocity phase space detected at 0.3 AU in fast solar wind. For explaining proton distributions obtained in the fast solar wind from 0.7 AU to 1 AU hot plasma dispersion relation should be considered. We also give a theoretical relation of proton thermal anisotropy A and plasma parameter β.

  7. Shear flow induced wave couplings in the solar wind

    Energy Technology Data Exchange (ETDEWEB)

    Poedts, S. [KULeuven, Heverlee (Belgium). Centre for Plasma Astrophysics; Rogava, A.D. [Tbilisi State Univ. (Georgia). Dept. of Physics]|[International Centre for Theoretical Physics, Trieste (Italy); Mahajan, S.M. [Univ. of Texas, Austin, TX (United States). Institute for Fusion Studies]|[International Centre for Theoretical Physics, Trieste (Italy)

    1998-01-01

    A sheared background flow in a plasma induces coupling between different MHD wave modes, resulting in their mutual transformations with corresponding energy redistributing between the modes. In this way, the energy can be transfered from one wave mode to the other, but energy can also be added to or extracted from the background flow. In the present paper it is investigated whether the wave coupling and energy transfer mechanisms can operate under solar wind conditions. It is shown that this is indeed the case. Hence, the long-period waves observed in the solar wind at r > 0.3 AU might be generated by much faster periodic oscillations in the photosphere of the Sun. Other possible consequences for observable beat phenomena in the wind and the acceleration of the solar wind particles are also discussed.

  8. The Interplanetary Magnetic Field and Solar Wind Driven Magnetospheric Reconfiguration

    CERN Document Server

    Savov, E

    2002-01-01

    The magnetic disturbances are associated with electric currents as it is well checked at laboratory room scales and described by the Maxwell's equations of electromagnetic field. The analysis of spacecraft observations for more than a quarter of a century failed to provide a self-consistent three-dimensional picture of the solar wind-magnetosphere dynamo generated magnetospheric and ionospheric current systems. The proposed solar wind and the interplanetary magnetic field (IMF) driven reconfiguration of the earth's magnetosphere directly accounts for the observed magnetic disturbances. So role of the magnetospheric currents in creation of the magnetic disturbances is reconsidered in accordance with some poorly understood observations. A quantitative agreement with observations is demonstrated and a laboratory experiment to test the suggested model of the solar wind/IMF-magnetosphere interaction is described.

  9. Analysis of Ion Charge States in Solar Wind and CMEs

    Indian Academy of Sciences (India)

    Arati Dasgupta; J. M. Laming

    2008-03-01

    We discuss needs in dielectronic recombination data motivated by recent work directed at a quantitative understanding of ion charge states of various elements observed in situ in the solar wind and CMEs. The competing processes of ionization and recombination lead to departures from collision ionization equilibrium. The use of this as a diagnostic of acceleration and heating processes of the solar wind and CMEs is sensitive to the accuracy of the atomic rates in a way that steady state ionization equilibrium plasmas are not. The most pressing need is dielectronic recombination rates for ions Fe8+-12+. These are among the dominant species observed in various regions of the solar wind and CMEs, and in remotely sensed EUV spectra.

  10. PROTON KINETIC EFFECTS IN VLASOV AND SOLAR WIND TURBULENCE

    Energy Technology Data Exchange (ETDEWEB)

    Servidio, S.; Valentini, F.; Perrone, D.; Veltri, P. [Dipartimento di Fisica, Università della Calabria, I-87036 Cosenza (Italy); Osman, K. T.; Chapman, S. [Centre for Fusion, Space and Astrophysics, University of Warwick, Coventry, CV4 7AL (United Kingdom); Califano, F. [Dipartimento di Fisica and CNISM, Università di Pisa, I-56127 Pisa (Italy); Matthaeus, W. H., E-mail: sergio.servidio@fis.unical.it [Bartol Research Institute and Department of Physics and Astronomy, University of Delaware, Newark, DE 19716 (United States)

    2014-02-01

    Kinetic plasma processes are investigated in the framework of solar wind turbulence, employing hybrid Vlasov-Maxwell (HVM) simulations. Statistical analysis of spacecraft observation data relates proton temperature anisotropy T /T {sub ∥} and parallel plasma beta β{sub ∥}, where subscripts refer to the ambient magnetic field direction. Here, this relationship is recovered using an ensemble of HVM simulations. By varying plasma parameters, such as plasma beta and fluctuation level, the simulations explore distinct regions of the parameter space given by T /T {sub ∥} and β{sub ∥}, similar to solar wind sub-datasets. Moreover, both simulation and solar wind data suggest that temperature anisotropy is not only associated with magnetic intermittent events, but also with gradient-type structures in the flow and in the density. This connection between non-Maxwellian kinetic effects and various types of intermittency may be a key point for understanding the complex nature of plasma turbulence.

  11. Proton Kinetic Effects in Vlasov and Solar Wind Turbulence

    CERN Document Server

    Servidio, S; Valentini, F; Perrone, D; Califano, F; Chapman, S; Matthaeus, W H; Veltri, P

    2013-01-01

    Kinetic plasma processes have been investigated in the framework of solar wind turbulence, employing Hybrid Vlasov-Maxwell (HVM) simulations. The dependency of proton temperature anisotropy T_{\\perp}/T_{\\parallel} on the parallel plasma beta \\beta_{\\parallel}, commonly observed in spacecraft data, has been recovered using an ensemble of HVM simulations. By varying plasma parameters, such as plasma beta and fluctuation level, the simulations explore distinct regions of the parameter space given by T_{\\perp}/T_{\\parallel} and \\beta_{\\parallel}, similar to solar wind sub-datasets. Moreover, both simulation and solar wind data suggest that temperature anisotropy is not only associated with magnetic intermittent events, but also with gradient-type structures in the flow and in the density. This connection between non-Maxwellian kinetic effects and various types of intermittency may be a key point for understanding the complex nature of plasma turbulence.

  12. Flank solar wind interaction. Annual report, June 1991-July 1992

    Energy Technology Data Exchange (ETDEWEB)

    Moses, S.L.; Greenstadt, E.W.

    1992-08-01

    This report summarizes the results of the first 12 months of our program to study the interaction of the Earth's magnetosphere with the solar wind on the far flanks of the bow shock. This study employs data from the ISEE-3 spacecraft during its traversals of the Earth's magnetotail and correlative data from spacecraft monitoring the solar wind upstream. Our main effort to date has involved assembling data sets and developing new plotting programs. Two talks were given at the Spring Meeting of the American Geophysical Union describing our initial results from analyzing data from the far flank foreshock and magnetosheath. The following sections summarize our results.

  13. Solar Wind Electric Fields in the Ion Cyclotron Frequency Range

    CERN Document Server

    Kellogg, P J; Mozer, F S; Horbury, T S; Reme, H

    2006-01-01

    Measurements of fluctuations of electric fields in the frequency range from a fraction of one Hz to 12.5 Hz are presented, and corrected for the Lorentz transformation of magnetic fluctuations to give the electric fields in the plasma frame. The electric fields are large enough to provide the dominant force on the ions of the solar wind in the region near the ion cyclotron frequency of protons, larger than the force due to magnetic fluctuations. They provide sufficient velocity space diffusion or heating to counteract conservation of magnetic moment in the expanding solar wind to maintain nearly isotropic velocity distributions.

  14. Scale-free texture of the fast solar wind.

    Science.gov (United States)

    Hnat, B; Chapman, S C; Gogoberidze, G; Wicks, R T

    2011-12-01

    The higher-order statistics of magnetic field magnitude fluctuations in the fast quiet solar wind are quantified systematically, scale by scale. We find a single global non-Gaussian scale-free behavior from minutes to over 5 h. This spans the signature of an inertial range of magnetohydrodynamic turbulence and a ~1/f range in magnetic field components. This global scaling in field magnitude fluctuations is an intrinsic component of the underlying texture of the solar wind and puts a strong constraint on any theory of solar corona and the heliosphere. Intriguingly, the magnetic field and velocity components show scale-dependent dynamic alignment outside of the inertial range.

  15. Modified temperature-anisotropy instability thresholds in the solar wind.

    Science.gov (United States)

    Schlickeiser, R; Michno, M J; Ibscher, D; Lazar, M; Skoda, T

    2011-11-11

    The proton and electron temperature anisotropies in the solar wind are constrained by the instability thresholds for temperature-anisotropy-driven kinetic plasma instabilities. The modifications to the marginal instability conditions from accounting for the influence of damping connected with the collisional effects in the solar wind plasma are calculated for right- and left-handed polarized parallel propagating Alfvén waves and mirror and firehose fluctuations. These modifications provide tighter threshold constraints compared to the marginal thresholds but do not fully explain the observations at small values of the parallel plasma beta.

  16. Ion kinetic scale in the solar wind observed.

    Science.gov (United States)

    Śafránková, Jana; Němeček, Zdeněk; Přech, Lubomír; Zastenker, Georgy N

    2013-01-11

    This Letter shows the first results from the solar wind monitor onboard the Spektr-R spacecraft which measures plasma moments with a time resolution of 31 ms. This high-time resolution allows us to make direct observations of solar wind turbulence below ion kinetic length scales. We present examples of the frequency spectra of the density, velocity, and thermal velocity. Our study reveals that although these parameters exhibit the same behavior at the magnetohydrodynamic scale, their spectra are remarkably different at the kinetic scale.

  17. Modeling Jets in the Corona and Solar Wind

    CERN Document Server

    Torok, T; Titov, V S; Leake, J E; Mikic, Z; Linker, J A; Linton, M G

    2015-01-01

    Coronal jets are transient, collimated eruptions that occur in regions of predominantly open magnetic field in the solar corona. Our understanding of these events has greatly evolved in recent years but several open questions, such as the contribution of coronal jets to the solar wind, remain. Here we present an overview of the observations and numerical modeling of coronal jets, followed by a brief description of "next-generation" simulations that include an advanced description of the energy transfer in the corona ("thermodynamic MHD"), large spherical computational domains, and the solar wind. These new models will allow us to address some of the open questions.

  18. Minimal Magnetic States of the Sun and the Solar Wind: Implications for the Origin of the Slow Solar Wind

    Science.gov (United States)

    Cliver, E. W.; von Steiger, R.

    2017-09-01

    During the last decade it has been proposed that both the Sun and the solar wind have minimum magnetic states, lowest order levels of magnetism that underlie the 11-yr cycle as well as longer-term variability. Here we review the literature on basal magnetic states at the Sun and in the heliosphere and draw a connection between the two based on the recent deep 2008-2009 minimum between cycles 23 and 24. In particular, we consider the implications of the low solar activity during the recent minimum for the origin of the slow solar wind.

  19. Velocity and abundance of silicon ions in the solar wind

    Energy Technology Data Exchange (ETDEWEB)

    Bochsler, P.

    1989-03-01

    Using data from the ISEE-3 ion composition instrument (ICI), velocities and abundances of silicon ions in the solar wind have been determined. The period of investigation covers the maximum of solar cycle 21, beginning with launch of ISEE-3 in August 1978 and ending at the removal of the spacecraft from the Lagrangian Point L1 in June 1982. The results generally confirm previous ICI observations of iron, the other heavy element with a low first ionization potential measured with the ICI. Silicon ions (and other ions in the same M/Q range) tend to stream at the bulk velocity of /sup 4/He/sup + +/ in low-speed solar wind. At high-speed solar wind. Si lags by up to or about 20 km/s after /sup 4/He/sup + +/. By means of a minimum variance estimation technique, fluxes (and densities) of silicon in the solar wind have been obtained free of bias. An average Si/O flux ratio of 0.19 +- 0.04 is derived. This value is larger by a factor of 3 or 4 than the Si/O abundance ratio at the solar surface. copyright American Geophysical Union 1989

  20. The Solar Wind in the Outer Heliosphere and Heliosheath

    Science.gov (United States)

    Richardson, J. D.; Burlaga, L. F.

    2011-01-01

    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.

  1. Modulation of Saturn's radio clock by solar wind speed.

    Science.gov (United States)

    Zarka, Philippe; Lamy, Laurent; Cecconi, Baptiste; Prangé, Renée; Rucker, Helmut O

    2007-11-08

    The internal rotation rates of the giant planets can be estimated by cloud motions, but such an approach is not very precise because absolute wind speeds are not known a priori and depend on latitude: periodicities in the radio emissions, thought to be tied to the internal planetary magnetic field, are used instead. Saturn, despite an apparently axisymmetric magnetic field, emits kilometre-wavelength (radio) photons from auroral sources. This emission is modulated at a period initially identified as 10 h 39 min 24 +/- 7 s, and this has been adopted as Saturn's rotation period. Subsequent observations, however, revealed that this period varies by +/-6 min on a timescale of several months to years. Here we report that the kilometric radiation period varies systematically by +/-1% with a characteristic timescale of 20-30 days. Here we show that these fluctuations are correlated with solar wind speed at Saturn, meaning that Saturn's radio clock is controlled, at least in part, by conditions external to the planet's magnetosphere. No correlation is found with the solar wind density, dynamic pressure or magnetic field; the solar wind speed therefore has a special function. We also show that the long-term fluctuations are simply an average of the short-term ones, and therefore the long-term variations are probably also driven by changes in the solar wind.

  2. Simulation of turbulent magnetic reconnection in the smallscale solar wind

    Institute of Scientific and Technical Information of China (English)

    魏奉思; 胡强; R.Schwen; 冯学尚

    2000-01-01

    Some observational examples for the possible occurrence of the turbulent magnetic reconnection in the solar wind are found by analysing Helios spacecraft’s high resolution data. The phenom-ena of turbulent magnetic reconnections in small scale solar wind are simulated by introducing a third order accuracy upwind compact difference scheme to the compressible two-dimensional MHD flow. Numerical results verify that the turbulent magnetic reconnection process could occur in small scale in-terplanetary solar wind, which is a basic feature characterizing the magnetic reconnection in high-mag-netie Peynolds number ( RM = 2 000-10 000) solar wind. The configurations of the magnetic reconnection could evolve from a single X-line to a multiple X-line reconnection, exhibiting a complex picture of the formation, merging and evolution of magnetic islands, and finally the magnetic reconnection would evolve into a low-energy state. Its life-span of evolution is about one hour order of magnitude. Various magnetic and f

  3. Global solar wind variations over the last four centuries.

    Science.gov (United States)

    Owens, M J; Lockwood, M; Riley, P

    2017-01-31

    The most recent "grand minimum" of solar activity, the Maunder minimum (MM, 1650-1710), is of great interest both for understanding the solar dynamo and providing insight into possible future heliospheric conditions. Here, we use nearly 30 years of output from a data-constrained magnetohydrodynamic model of the solar corona to calibrate heliospheric reconstructions based solely on sunspot observations. Using these empirical relations, we produce the first quantitative estimate of global solar wind variations over the last 400 years. Relative to the modern era, the MM shows a factor 2 reduction in near-Earth heliospheric magnetic field strength and solar wind speed, and up to a factor 4 increase in solar wind Mach number. Thus solar wind energy input into the Earth's magnetosphere was reduced, resulting in a more Jupiter-like system, in agreement with the dearth of auroral reports from the time. The global heliosphere was both smaller and more symmetric under MM conditions, which has implications for the interpretation of cosmogenic radionuclide data and resulting total solar irradiance estimates during grand minima.

  4. Sputtering by the Solar Wind: Effects of Variable Composition

    Science.gov (United States)

    Killen, R. M.; Arrell, W. M.; Sarantos, M.; Delory, G. T.

    2011-01-01

    It has long been recognized that solar wind bombardment onto exposed surfaces in the solar system will produce an energetic component to the exospheres about those bodies. Laboratory experiments have shown that there is no increase in the sputtering yield caused by highly charged heavy ions for metallic and for semiconducting surfaces, but the sputter yield can be noticeably increased in the case of a good insulating surface. Recently measurements of the solar wind composition have become available. It is now known that the solar wind composition is highly dependent on the origin of the particular plasma. Using the measured composition of the slow wind, fast wind, solar energetic particle (SEP) population, and coronal mass ejection (CME), broken down into its various components, we have estimated the total sputter yield for each type of solar wind. Whereas many previous calculations of sputtering were limited to the effects of proton bombardment. we show that the heavy ion component. especially the He++ component. can greatly enhance the total sputter yield during times when the heavy ion population is enhanced. We will discuss sputtering of both neutrals and ions.

  5. Source of electrostatic fluctuations in the solar wind

    Energy Technology Data Exchange (ETDEWEB)

    Lemons, D.S.; Asbridge, J.R.; Bame, S.J.; Feldman, W.C.; Peter Gray, S.; Gosling, J.T.

    1979-05-01

    Solar wind electron and ion distribution functions measured simultaneously with or close to times of intense electrostatic fluctuations are subjected to a linear Vlasov stability analysis. Although all distributions tested were found to be stable, the analysis suggests that the ion beam instability is the most likely source of the fluctuations.

  6. Solar Wind Simulations Based on Ooty IPS Data

    Science.gov (United States)

    Muehe, S. C.; Kim, T. K.; Pogorelov, N. V.

    2014-12-01

    The solar wind is a constantly-flowing stream of charged particles that expands from the sun's outer atmosphere into interplanetary space. This plasma carries the sun's magnetic field along with it, where it interacts with and causes disruptions in the earth's magnetic field. Our understanding of the solar wind is vital to efforts toward minimizing the impact of these disturbances on both ground and space-based systems. Using interplanetary scintillation data gathered by the ground-based Ooty Radio Telescope (ORT) in India, we have constructed boundary maps of solar wind velocities at 1 day intervals. For a simple, first approximation, we use what is called the "P-point" method to crudely estimate the solar wind velocity at the point of closest approach to the Sun along each line of sight. Then we trace the P-point values back to a spherical surface at 0.2 AU where we interpolate them to a structured gird. The resulting boundary maps can serve as the initial input to a time-dependent MHD tomography program being developed at the University of Alabama in Huntsville.

  7. Tsallis non-extensive statistics and solar wind plasma complexity

    Science.gov (United States)

    Pavlos, G. P.; Iliopoulos, A. C.; Zastenker, G. N.; Zelenyi, L. M.; Karakatsanis, L. P.; Riazantseva, M. O.; Xenakis, M. N.; Pavlos, E. G.

    2015-03-01

    This article presents novel results revealing non-equilibrium phase transition processes in the solar wind plasma during a strong shock event, which took place on 26th September 2011. Solar wind plasma is a typical case of stochastic spatiotemporal distribution of physical state variables such as force fields (B → , E →) and matter fields (particle and current densities or bulk plasma distributions). This study shows clearly the non-extensive and non-Gaussian character of the solar wind plasma and the existence of multi-scale strong correlations from the microscopic to the macroscopic level. It also underlines the inefficiency of classical magneto-hydro-dynamic (MHD) or plasma statistical theories, based on the classical central limit theorem (CLT), to explain the complexity of the solar wind dynamics, since these theories include smooth and differentiable spatial-temporal functions (MHD theory) or Gaussian statistics (Boltzmann-Maxwell statistical mechanics). On the contrary, the results of this study indicate the presence of non-Gaussian non-extensive statistics with heavy tails probability distribution functions, which are related to the q-extension of CLT. Finally, the results of this study can be understood in the framework of modern theoretical concepts such as non-extensive statistical mechanics (Tsallis, 2009), fractal topology (Zelenyi and Milovanov, 2004), turbulence theory (Frisch, 1996), strange dynamics (Zaslavsky, 2002), percolation theory (Milovanov, 1997), anomalous diffusion theory and anomalous transport theory (Milovanov, 2001), fractional dynamics (Tarasov, 2013) and non-equilibrium phase transition theory (Chang, 1992).

  8. Coherent structure and Intermittent Turbulence in the Solar Wind Plasma

    Science.gov (United States)

    Sondhiya, Deepak Kumar; Gwal, Ashok Kumar; Kasde, Satish Kumar

    2016-07-01

    We analyze the coherent structures and intermittent turbulence in the solar wind plasma using measurements from the Wind spacecraft. Previously established novel wavelet and higher order statistics are used in this work. We analyze the wavelet power spectrum of various solar wind plasma parameters. We construct a statistical significance level in the wavelet power spectrum to quantify the interference effects arising from filling missing data in the time series, allowing extraction of significant power from the measured data. We analyze each wavelet power spectra for transient coherency, and global periodicities resulting from the superposition of repeating coherent structures. Furthermore, these coherent structures are preferentially found in plasma unstable to the mirror and firehose instabilities. These results offer a new understanding of various processes in a turbulent regime. Finally, we discuss the implications of our results for current theories of solar wind generation and describe future work for determining the relationship between the coherent structures in our ionic composition data and the structure of the coronal magnetic field. Keywords: Wavelet Power Spectrum, Coherent structure and Solar wind plasma

  9. Global solar wind variations over the last four centuries

    Science.gov (United States)

    Owens, M. J.; Lockwood, M.; Riley, P.

    2017-01-01

    The most recent “grand minimum” of solar activity, the Maunder minimum (MM, 1650–1710), is of great interest both for understanding the solar dynamo and providing insight into possible future heliospheric conditions. Here, we use nearly 30 years of output from a data-constrained magnetohydrodynamic model of the solar corona to calibrate heliospheric reconstructions based solely on sunspot observations. Using these empirical relations, we produce the first quantitative estimate of global solar wind variations over the last 400 years. Relative to the modern era, the MM shows a factor 2 reduction in near-Earth heliospheric magnetic field strength and solar wind speed, and up to a factor 4 increase in solar wind Mach number. Thus solar wind energy input into the Earth’s magnetosphere was reduced, resulting in a more Jupiter-like system, in agreement with the dearth of auroral reports from the time. The global heliosphere was both smaller and more symmetric under MM conditions, which has implications for the interpretation of cosmogenic radionuclide data and resulting total solar irradiance estimates during grand minima.

  10. On the properties of energy transfer in solar wind turbulence.

    Science.gov (United States)

    Sorriso-Valvo, Luca; Marino, Raffaele; Chen, Christopher H. K.; Wicks, Robert; Nigro, Giuseppina

    2017-04-01

    Spacecraft observations have shown that the solar wind plasma is heated during its expansion in the heliosphere. The necessary energy is made available at small scales by a turbulent cascade, although the nature of the heating processes is still debated. Because of the intermittent nature of turbulence, the small-scale energy is inhomogeneously distributed in space, resulting for example in the formation of highly localized current sheets and eddies. In order to understand the small-scale plasma processes occurring in the solar wind, the global and local properties of such energy distribution must be known. Here we study such properties using a proxy derived from the Von Karman-Howart relation for magnetohydrodynamics. The statistical properties of the energy transfer rate in the fluid range of scales are studied in detail using WIND spacecraft plasma and magnetic field measurements and discussed in the framework of the multifractal turbulent cascade. Dependence of the energy dissipation proxy on the solar wind conditions (speed, type, solar activity...) is analysed, and its evolution during solar wind expansion in the heliosphere is described using Helios II and Ulysses measurements. A comparison with other proxies, such as the PVI, is performed. Finally, the local singularity properties of the energy dissipation proxy are conditionally compared to the corresponding particle velocity distributions. This allows the identification of specific plasma features occurring near turbulent dissipation events, and could be used as enhanced mode trigger in future space missions.

  11. Solar Wind ~20-300 keV Superhalo Electrons

    Science.gov (United States)

    Wang, L.; Yang, L.; He, J.; Tu, C. Y.; Pei, Z.

    2014-12-01

    High-energy superhalo electrons are present in the interplanetary medium even in absence of any solar activity, carrying important information on the electron acceleration in the solar wind. We present a statistical survey of ~20-300 keV superhalo electrons measured at 1 AU by the WIND 3DP instrument during quiet-time periods from 1995 January through 2013 December. The velocity distribution function of the observed quiet-time superhalo electrons generally fits to a power-law spectrum, f ~ v-γ, with γ ranging from ~4 to ~10. The integrated density of these superhalo electrons at 20-300 keV, nsup, ranges from 10-9 cm-3 to 10-5 cm-3. Both log(nsup) and γ show a good correlation with the sunspot number, with larger density and softer spectrum (γ~ 6-8) at solar maximum, and smaller density and harder spectrum (γ~ 4-5) at solar minimum. The observed power-law spectrum also has no clear association with flares, CMEs, active regions and solar wind core populations, while it shows a weak (~0.3) correlation with in situ solar wind turbulence spectrum. These results suggest that the seed particles of quiet-time superhalo electrons could originate from the Sun, and their acceleration could mainly occur in the interplanetary medium, probably by the electron interaction with solar wind turbulence, or by acceleration at the CIRs.

  12. Magnetosheath control of solar wind-magnetosphere coupling efficiency

    Science.gov (United States)

    Pulkkinen, T. I.; Dimmock, A. P.; Lakka, A.; Osmane, A.; Kilpua, E.; Myllys, M.; Tanskanen, E. I.; Viljanen, A.

    2016-09-01

    We examine the role of the magnetosheath in solar wind-magnetosphere-ionosphere coupling using the Time History of Events and Macroscale Interactions during Substorms plasma and magnetic field observations in the magnetosheath together with OMNI solar wind data and auroral electrojet recordings from the International Monitor for Auroral Geomagnetic Effects (IMAGE) magnetometer chain. We demonstrate that the electric field and Poynting flux reaching the magnetopause are not linear functions of the electric field and Poynting flux observed in the solar wind: the electric field and Poynting flux at the magnetopause during higher driving conditions are lower than those predicted from a linear function. We also show that the Poynting flux normal to the magnetopause is linearly correlated with the directly driven part of the auroral electrojets in the ionosphere. This indicates that the energy entering the magnetosphere in the form of the Poynting flux is directly responsible for driving the electrojets. Furthermore, we argue that the polar cap potential saturation discussed in the literature is associated with the way solar wind plasma gets processed during the bow shock crossing and motion within the magnetosheath.

  13. XMM-Newton Observations of Solar Wind Charge Exchange Emission

    Science.gov (United States)

    Snowden, S. L.; Collier, M. R.; Kuntz, K. D.

    2004-01-01

    We present an XMM-Newton spectrum of diffuse X-ray emission from within the solar system. The spectrum is dominated by O VII and O VIII lines at 0.57 keV and 0.65 keV, O VIII (and possibly Fe XVII) lines at approximately 0.8 keV, Ne IX lines at approximately 0.92 keV, and Mg XI lines at approximately 1.35 keV. This spectrum is consistent with what is expected from charge exchange emission between the highly ionized solar wind and either interstellar neutrals in the heliosphere or material from Earth's exosphere. The emission is clearly seen as a low-energy ( E less than 1.5 keV) spectral enhancement in one of a series of observations of the Hubble Deep Field North. The X-ray enhancement is concurrent with an enhancement in the solar wind measured by the ACE satellite. The solar wind enhancement reaches a flux level an order of magnitude more intense than typical fluxes at 1 AU, and has ion ratios with significantly enhanced higher ionization states. Whereas observations of the solar wind plasma made at a single point reflect only local conditions which may only be representative of solar wind properties with spatial scales ranging from less than half of an Earth radii (approximately 10 s) to 100 Earth radii, X-ray observations of solar wind charge exchange are remote sensing measurements which may provide observations which are significantly more global in character. Besides being of interest in its own right for studies of the solar system, this emission can have significant consequences for observations of more cosmological objects. It can provide emission lines at zero redshift which are of particular interest (e.g., O VII and O VIII) in studies of diffuse thermal emission, and which can therefore act as contamination in objects which cover the entire detector field of view. We propose the use of solar wind monitoring data, such as from the ACE and Wind spacecraft, as a diagnostic to screen for such possibilities.

  14. Enigmatic Solar Wind Disappearance Events – Do We Understand Them?

    Indian Academy of Sciences (India)

    Janardhan P.

    2006-06-01

    At the Sun–Earth distance of one astronomical unit (1 AU), the solar wind is known to be strongly supersonic and super Alfvénic with Mach and Alfvén numbers being on average 12 and 9 respectively. Also, solar wind densities (average ∼ 10 cm-3) and velocities (average ∼ 450 km s-1) at 1 AU, are known to be inversely correlated with low velocities having higher than average densities and vice versa. However, on May 11 and 12 1999 the Earth was engulfed by an unusually low density (< 0.1 cm-3) and low velocity (< 350 km s-1) solar wind with an Alfvén Mach number significantly less than 1. This was a unique low-velocity, low-density, sub-Alfvénic solar wind flow which spacecraft observations have shown lasted more than 24 hours. One consequence of this extremely tenuous solar wind was a spectacular expansion of the Earth’s magnetosphere and bow shock. The expanding bow shock was observed by several spacecraft and reached record upstream distances of nearly 60 Earth radii, the lunar orbit. The event was so dramatic that it has come to be known as the solar wind disappearance event. Though extensive studies of this event were made by many authors in the past, it has only been recently shown that the unusual solar wind flows characterizing this event originated from a small coronal hole in the vicinity of a large active region on the Sun. These recent results have put to rest speculation that such events are associated with global phenomenon like the periodic solar polar field reversal that occurs at the maximum of each solar cycle. In this paper we revisit the 11 May 1999 event, look at other disappearance events that have ocurred in the past, examine the reasons why speculations about the association of such events with global phenomena like solar polar field reversals were made and also examine the role of transient coronal holes as a possible solar source for such events.

  15. Weak and strong comets in the solar wind

    Science.gov (United States)

    Jones, Geraint Hughes

    When within the inner solar system, comets possess gaseous atmospheres. The gases therein are ionized, and eventually join the solar wind. This thesis describes an investigation of the interaction of comets with the solar wind. The work begins with an overview of the processes involved in the comet-solar wind interaction region, and the domains and boundaries that exist in the region. A review of remote observations of cometary ions is given. The characteristics of visible plasma features are summarized, together with the theories proposed to explain them. An overview of the Giotto spacecraft and its instruments, and a description of its mission to two comets are presented. Ground-based observations were obtained of the ion features present in Comet C/1996 B2 Hyakutake. The morphologies and motions of the comet's plasma features are described. The formation of tail rays was captured during a high temporal resolution image sequence. A gas production rate estimate is derived from the observations, and a model of ray morphologies is proposed, based partly upon observational evidence. 45P/Honda-Mrkos-Pajdusakova and C/1996 Q1 Tabur were also observed; however, no strong ion features were detected. An analysis of the plasma features of 26P/Grigg-Skjellerup then follows. A description of the solar wind conditions at that comet during the Giotto encounter is given, and an estimate of its production rate is made. Ground-based observations of Grigg-Skjellerup are compared to in-situ Giotto data. Morphological features were detected in ground-based images; it is proposed that they could have been linked to certain solar wind discontinuities. A qualitative description of a model of ion ray formation then follows. The thesis concludes with a summary of the main results.

  16. The Importance of Suprathermal Electrons in the Solar Wind

    Science.gov (United States)

    LE CHAT, G.; Meyer-Vernet, N.; Pantellini, F. G. E.; Issautier, K.; Moncuquet, M.

    2014-12-01

    Non-Gaussian distributions are ubiquitous in systems having long-range interactions, from real-world networks to astrophysical plasmas. The corona and solar wind are no exception. In this review, we concentrate on the corona and solar wind electrons, whose suprathermal tail governs heat transport and plays a crucial role in the temperature structure and wind production, as first suggested thirty years ago by Olbert and confirmed by a large number of subsequent studies. These non-thermal electrons have been measured in both the corona and solar wind, and are a direct consequence of the fast increase with speed of the Coulomb free-path, compared to the pressure scale-height. This situation has four important consequences: (1) the fluid description, on which the vast majority of solar wind models are based is inadequate; (2) the heat flux is NOT given by the classical Spitzer-Härm expression in the corona and solar wind; (3) for most non-thermal distributions (except the convenient and fashionable Kappa distribution), the fraction of supra-thermal electrons increases with altitude in the corona because of velocity filtration; for example, with a sum of Maxwellians, the hotter the population, the larger the increase with altitude of its fractional contribution; (4) ad-hoc heat addition - assumed in most models, is not necessarily required to produce the observed variation in temperature and the wind acceleration. We will shortly review the observed electron velocity distributions together with the theoretical expectations, the major role of the electric field and the consequences on the heat flux, the temperature structure and the wind acceleration.

  17. Solar Wind Fluctuations and Their Consequences on the Magnetosphere

    Science.gov (United States)

    Li, Xin-Lin

    2005-01-01

    Efforts have been made to extract the physical meaning of each term in our prediction model of the Dst index using the solar wind as the only input. The work has been published Journal of Geophysical Research (Temerin and Li, 21002). We found different terms in the model representing different current in the magnetospheric system and each current has different rise and decay times, with the symmetric ring current the slowest, then the partial ring current, then the tail current. We also have been trying to understand the physical meaning of the diffusion coefficient used in our prediction model of relativistic electron fluxes at geostationary orbit. The model reproduced the observations of MeV electron flux variations well, the diffusion coefficient had be assumed only die to local magnetic field fluctuations, leading to its 10th power dependence on the L. We have studied the theoretical derivation of the diffusion coefficient and we believe that the effect electric field fluctuations at smaller L could become more significant. We have expanded our previous radiation belt electron prediction model, which predicted MeV electron geosynchronous orbit based on solar wind measurements, to predict MeV electrons inside geosynchronous orbit. The model results are compared with measurements from Polar/CEPPAD. Prediction efficiencies of 0.56 and 0.54, respectively, at L=6 and L=4, have been achieved over the entire year of 1998. This work wa reported at 2003 Fall AGU and has been accepted for publication in Space Weather (Barker et al., 2005). We also have used simultaneous measurements of the upstream solar wind and of energetic electrons at geosynchronous orbit to analyze the response of electrons over a very wide energy range, 50 keV-6MeV, to solar wind variations. Enhancements of energetic electron fluxes over this whole energy range are modulated by the solar wind speed and the polarity of the interplanetary magnetic field (IMF). The solar wind speed seems to be a

  18. Solar wind induced magnetic field around the unmagnetized Earth

    CERN Document Server

    Birk, G T; Konz, C

    2004-01-01

    The Earth is a planet with a dipolar magnetic field which is agitated by a magnetized plasma wind streaming from the Sun. The magnetic field shields the Earth's surface from penetrating high energy solar wind particles, as well as interstellar cosmic rays. The magnetic dipole has reversed sign some hundreds of times over the last 400 million years. These polarity reversals correspond to drastic breakdowns of the dynamo action. The question arises what the consequences for the Earth's atmosphere, climate, and, in particular, biosphere are. It is shown by kinematic estimates and three-dimensional plasma-neutral gas simulations that the solar wind can induce very fast a magnetic field in the previously completely unmagnetized Earth's ionosphere that is strong enough to protect Earth from cosmic radiations comparable to the case of an intact magnetic dynamo.

  19. MHD effects of the solar wind flow around planets

    Directory of Open Access Journals (Sweden)

    H. K. Biernat

    2000-01-01

    Full Text Available The study of the interaction of the solar wind with magnetized and unmagnetized planets forms a central topic of space research. Focussing on planetary magnetosheaths, we review some major developments in this field. Magnetosheath structures depend crucially on the orientation of the interplanetary magnetic field, the solar wind Alfvén Mach number, the shape of the obstacle (axisymmetric/non-axisymmetric, etc., the boundary conditions at the magnetopause (low/high magnetic shear, and the degree of thermal anisotropy of the plasma. We illustrate the cases of Earth, Jupiter and Venus. The terrestrial magnetosphere is axisymmetric and has been probed in-situ by many spacecraft. Jupiter's magnetosphere is highly non-axisymmetric. Furthermore, we study magnetohydrodynamic effects in the Venus magnetosheath.

  20. The Solar Wind Around Pluto (SWAP) Instrument Aboard New Horizons

    CERN Document Server

    McComas, D; Bagenal, F; Casey, P; Delamere, P; Demkee, D; Dunn, G; Elliott, H; Hanley, J; Johnson, K; Langle, J; Miller, G; Pope, S; Reno, M; Rodríguez, B; Schwadron, N; Valek, P; Weidner, S

    2007-01-01

    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. In order to meet these unique requirements, we combined a cylindrically symmetric retarding potential analyzer (RPA) 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.

  1. What geometrical factors determine the in situ solar wind speed?

    CERN Document Server

    Li, Bo; Xia, Li-Dong

    2011-01-01

    At present it remains to address why the fast solar wind is fast and the slow wind is slow. Recently we have shown that the field line curvature may substantially influence the wind speed $v$, thereby offering an explanation for the Arge et al. finding that $v$ depends on more than just the flow tube expansion factor. Here we show by extensive numerical examples that the correlation between $v$ and field line curvature is valid for rather general base boundary conditions and for rather general heating functions. Furthermore, the effect of field line curvature is even more pronounced when the proton-alpha particle speed difference is examined. We suggest that any solar wind model has to take into account the field line shape for any quantitative analysis to be made.

  2. Coronal Streamers and Their Associated Solar Wind Streams

    Science.gov (United States)

    Miralles, M. P.; Landi, E.; Cranmer, S. R.; Cohen, O.; Raymond, J. C.

    2012-12-01

    We use the EUV spectrometers aboard SOHO and Hinode and white-light coronagraphs to characterize the physical properties of coronal streamers during Earth/Ulysses quadrature configurations for the previous two solar minimum periods. In addition, comparisons between coronal observations and in situ measurements of solar wind plasma properties are being used to further characterize the origins of slow wind streams. In order to investigate slow solar wind heating and acceleration, we also compare with predictions from three-dimensional MHD models. We aim to use the empirical measurements to distinguish between different proposed physical processes for slow wind acceleration (e.g., waves/turbulence versus reconnection). This work is supported by NASA grant NNX10AQ58G to the Smithsonian Astrophysical Observatory.

  3. A review on solar wind modeling: kinetic and fluid aspects

    CERN Document Server

    Echim, Marius; Lie-Svendsen, Oystein

    2013-01-01

    We review the main advantages and limitations of the kinetic exospheric and fluid models of the solar wind (SW). We discuss the hydrostatic model imagined by Chapman, the first supersonic hydrodynamic models published by Parker and the first generation subsonic kinetic model proposed by Chamberlain. It is shown that a correct estimation of the electric field as in the second generation kinetic exospheric models developed by Lemaire and Scherer, provides a supersonic expansion of the corona, reconciling the hydrodynamic and the kinetic approach. The third generation kinetic exospheric models considers kappa velocity distribution function (VDF) instead of a Maxwellian at the exobase and in addition they treat a non-monotonic variation of the electric potential with the radial distance; the fourth generation exospheric models include Coulomb collisions based on the Fokker--Planck collision term. Multi-fluid models of the solar wind provide a coarse grained description and reproduce with success the spatio-tempor...

  4. Charge Exchange Losses and Stochastic Acceleration in the Solar Wind

    CERN Document Server

    Kenny, Ciaran

    2016-01-01

    Stochastic acceleration of particles under a pressure balance condition can accommodate the universal $p^{-5}$ spectra observed under many different conditions in the inner heliosphere. In this model, in order to avoid an infinite build up of particle pressure, a relationship between the momentum diffusion of particles and the adiabatic deceleration in the solar wind must exist. This constrains both the spatial and momentum diffusion coefficients and results in the $p^{-5}$ spectrum in the presence of adiabatic losses in the solar wind. However, this theory cannot explain the presence of such spectra beyond the termination shock, where adiabatic deceleration is negligible. To explain this apparent discrepancy, we include the effect of charge exchange losses, resulting in new forms of both the spatial and momentum diffusion coefficients that have not previously been considered. Assuming that the turbulence is of a large-scale compressible nature, we find that a balance between momentum diffusion and losses can...

  5. Solar wind and micrometeorite effects in the lunar regolith

    Science.gov (United States)

    Housley, R. M.

    1977-01-01

    Using available data from the literature, an outline is formulated for the major physical and chemical effects expected during solar-wind bombardment of the lunar regolith. In agreement with results of Auger and other analyses of the composition of lunar grain surfaces, this outline predicts that solar-wind sputtering will tend to clean exposed grain surfaces by ejecting material at velocities exceeding lunar escape velocity. Results are also discussed which show that Fe is partially reduced in the outer few 10 nm of grain surfaces and that this reduced Fe forms 10-nm-diameter metal spheres throughout the glass during agglutinate formation by micrometeorite impacts. These metal spheres give the agglutinates their distinctive optical and magnetic properties and are partially responsible for the decreasing albedo of the lunar surface with exposure age.

  6. Influence of upstream solar wind on thermospheric flows at Jupiter

    CERN Document Server

    Yates, J N; Guio, P

    2010-01-01

    The coupling of Jupiter's magnetosphere and ionosphere plays a vital role in creating its auroral emissions. The strength of these emissions is dependent on the difference in speed of the rotational flows within Jupiter's high-latitude thermosphere and the planet's magnetodisc. Using an azimuthally symmetric global circulation model, we have simulated how upstream solar wind conditions affect the energy and direction of atmospheric flows. In order to simulate the effect of a varying dynamic pressure in the upstream solar wind, we calculated three magnetic field profiles representing compressed, averaged and expanded `middle' magnetospheres. These profiles were then used to solve for the angular velocity of plasma in the magnetosphere. This angular velocity determines the strength of currents flowing between the ionosphere and magnetosphere. We examine the influence of variability in this current system upon the global winds and energy inputs within the Jovian thermosphere. We find that the power dissipated by...

  7. Photonic spin control for solar wind electric sail

    CERN Document Server

    Janhunen, P

    2012-01-01

    The electric solar wind sail (E-sail) is a novel, efficient propellantless propulsion concept which utilises the natural solar wind for spacecraft propulsion with the help of long centrifugally stretched charged tethers. The E-sail requires auxiliary propulsion applied to the tips of the main tethers for creating the initial angular momentum and possibly for modifying the spinrate later during flight to counteract the orbital Coriolis effect and possibly for mission specific reasons. We introduce the possibility of implementing the required auxiliary propulsion by small photonic blades (small radiation pressure solar sails). The blades would be stretched centrifugally. We look into two concepts, one with and one without auxiliary tethers. The use of photonic blades has the benefit of providing sufficient spin modification capability for any E-sail mission while keeping the technology fully propellantless. We conclude that the photonic blades appear to be a feasible and attractive solution to E-sail spinrate c...

  8. The global interaction of comets with the solar wind

    Science.gov (United States)

    Houpis, Harry L. F.

    1987-01-01

    The recent in-situ measurements of the plasma-neutral gas environment of comet Halley by the GIOTTO and VEGA spacecraft have confirmed the global theory of the comet-solar wind interaction. The ionopause, cometopause, and bow shock distances are the primary predictions of the model, although various momentum collisional cross-sections can also be estimated. With this greater confidence in the global model, the sharp Sunward intensity decrease in the spatial H2O+ profiles observed for comet Halley between 2.14 AU pre- and post-perihelion are interpreted as the cometopause boundary. This interpretation may then be used to determine the solar wind conditions local to the comet.

  9. Recent observations of MHD fluctuations in the solar wind

    Directory of Open Access Journals (Sweden)

    B. Bavassano

    Full Text Available A short review of recent observations of solar wind fluctuations in the magnetohydrodynamic (MHD range of scales is presented. In recent years, the use of high time-resolution data on an extended interval of heliocentric distance has allowed significant advances in our knowledge of MHD fluctuations. We first focus on the origin and evolution of the Alfvénic-type fluctuations. The role of interplanetary sources and the influence of interactions with structures convected by the solar wind are examined. Then compressive fluctuations are investigated, with special attention being given to their nature and origin. Observations are discussed in the light of recent theories and models. Finally, predictions for MHD turbulence in polar regions of the heliosphere are highlighted.

  10. The dissipation of solar wind turbulent fluctuations at electron scales

    CERN Document Server

    Camporeale, Enrico

    2011-01-01

    We present two-dimensional fully-kinetic Particle-in-Cell simulations of decaying electromagnetic fluctuations. The computational box is such that wavelengths ranging from electron to ion gyroradii are resolved. The parameters used are realistic for the solar wind, and the ion to electron mass ratio is physical. The understanding of the dissipation of turbulent fluctuations at small scales is thought to be a crucial mechanism for solar wind acceleration and coronal heating. The computational results suggest that a power law cascade of magnetic fluctuations could be sustained up to scales of the electron Larmor radius and smaller. We analyse the simulation results in the light of the Vlasov linear theory, and we comment on the particle heating. The dispersion curves of lightly damped modes in this regime suggest that a linear mechanism could be responsible for the observed steepening of power spectra at electron scales, but a straightforward identification of turbulent fluctuations as an ensemble of linear mod...

  11. Magnetic Reconnection and Intermittent Turbulence in the Solar Wind

    CERN Document Server

    Osman, K T; Gosling, J T; Greco, A; Servidio, S; Hnat, B; Chapman, S C; Phan, T D

    2014-01-01

    A statistical relationship between magnetic reconnection, current sheets and intermittent turbulence in the solar wind is reported for the first time using in-situ measurements from the Wind spacecraft at 1 AU. We identify intermittency as non-Gaussian fluctuations in increments of the magnetic field vector, $\\mathbf{B}$, that are spatially and temporally non-uniform. The reconnection events and current sheets are found to be concentrated in intervals of intermittent turbulence, identified using the partial variance of increments method: within the most non-Gaussian 1% of fluctuations in $\\mathbf{B}$, we find 87%-92% of reconnection exhausts and $\\sim$9% of current sheets. Also, the likelihood that an identified current sheet will also correspond to a reconnection exhaust increases dramatically as the least intermittent fluctuations are removed from the dataset. Hence, the turbulent solar wind contains a hierarchy of intermittent magnetic field structures that are increasingly linked to current sheets, which ...

  12. Solar wind collimation of the Jupiter high velocity dust streams

    Science.gov (United States)

    Flandes, A.; Krueger, H.

    2006-12-01

    The dust bursts discovered by the Ulysses dust sensor when approaching Jupiter in 1992 were later confirmed as collimated streams of high velocity (~200 km/s) charged (~5V) dust grains escaping from Jupiter and dominated by the interplanetary Magnetic field (IMF). With Cassini, a similar phenomenon was observed in Saturn. It was demonstrated that the Jovian dust streams are closely related to the solar wind compressed regions, either Corotating interaction regions (CIRs) or Coronal mass ejections (CMEs) ¨Cto a minor extent-. Actually the dust streams seem ultimately to be generated by such events. This can be explained considering that dust grains are accelerated as they gain substantial energy while compressed at the forward and reverse shocks that bound or precede these solar wind regions.

  13. Predicted Impacts of Proton Temperature Anisotropy on Solar Wind Turbulence

    CERN Document Server

    Klein, Kristopher G

    2015-01-01

    Particle velocity distributions measured in the weakly collisional solar wind are frequently found to be non-Maxwellian, but how these non-Maxwellian distributions impact the physics of plasma turbulence in the solar wind remains unanswered. Using numerical solutions of the linear dispersion relation for a collisionless plasma with a bi-Maxwellian proton velocity distribution, we present a unified framework for the four proton temperature anisotropy instabilities, identifying the associated stable eigenmodes, highlighting the unstable region of wavevector space, and presenting the properties of the growing eigenfunctions. Based on physical intuition gained from this framework, we address how the proton temperature anisotropy impacts the nonlinear dynamics of the \\Alfvenic fluctuations underlying the dominant cascade of energy from large to small scales and how the fluctuations driven by proton temperature anisotropy instabilities interact nonlinearly with each other and with the fluctuations of the large-scal...

  14. (abstract) Ulysses Observations of Magnetic Nulls in the Solar Wind

    Science.gov (United States)

    Winterhalter, D.; Murphy, N.; Tsurutani, B. T.; Smith, E. J.; Balogh, A.; Erdos, G.

    1993-01-01

    High time resolution magnetic field measurements (1 vector/s) at radial distances out to 5.3 AU and heliographic latitudes from 0(deg) to > 35(deg) S reveal the presence of solitary pulses lasting tens of seconds in which the field magnitude approaches or reaches zero. The properties of these nulls, their spatial distribution and relation to solar wind structures and to similar-apppearing interplanetary and magnetospheric impulses will be discussed.

  15. Long-term Trends in the Solar Wind Proton Measurements

    Science.gov (United States)

    Elliott, Heather A.; McComas, David J.; DeForest, Craig E.

    2016-11-01

    We examine the long-term time evolution (1965-2015) of the relationships between solar wind proton temperature (T p) and speed (V p) and between the proton density (n p) and speed using OMNI solar wind observations taken near Earth. We find a long-term decrease in the proton temperature-speed (T p-V p) slope that lasted from 1972 to 2010, but has been trending upward since 2010. Since the solar wind proton density-speed (n p-V p) relationship is not linear like the T p-V p relationship, we perform power-law fits for n p-V p. The exponent (steepness in the n p-V p relationship) is correlated with the solar cycle. This exponent has a stronger correlation with current sheet tilt angle than with sunspot number because the sunspot number maxima vary considerably from cycle to cycle and the tilt angle maxima do not. To understand this finding, we examined the average n p for different speed ranges, and found that for the slow wind n p is highly correlated with the sunspot number, with a lag of approximately four years. The fast wind n p variation was less, but in phase with the cycle. This phase difference may contribute to the n p-V p exponent correlation with the solar cycle. These long-term trends are important since empirical formulas based on fits to T p and V p data are commonly used to identify interplanetary coronal mass ejections, but these formulas do not include any time dependence. Changes in the solar wind density over a solar cycle will create corresponding changes in the near-Earth space environment and the overall extent of the heliosphere.

  16. Scaling of the electron dissipation range of solar wind turbulence

    OpenAIRE

    2013-01-01

    Electron scale solar wind turbulence has attracted great interest in recent years. Clear evidences have been given from the Cluster data that turbulence is not fully dissipated near the proton scale but continues cascading down to the electron scales. However, the scaling of the energy spectra as well as the nature of the plasma modes involved at those small scales are still not fully determined. Here we survey 10 years of the Cluster search-coil magnetometer (SCM) waveforms measured in the s...

  17. The solar wind interaction with comets: A post encounter view

    Science.gov (United States)

    Mendis, D. A.

    1987-01-01

    The recent spacecraft encounters with comets Giacobini-Zinner and Halley have led to an enormous increase in our knowledge of comets, including their dust, neutral gas, plasma, and magnetic field environments. The latter has in turn led to better understanding of the nature of the solar wind interaction with the well developed atmosphere of a comet. The post-encounter understanding of this interaction is reviewed, underscoring the differences with pre-encounter reasoning. The problems outstanding in this area are emphasized.

  18. On the relation between ionospheric winter anomalies and solar wind

    Directory of Open Access Journals (Sweden)

    G. C. Rumi

    2001-06-01

    Full Text Available There are two different winter anomalies. A small one that appears in connection with ionization at relatively low latitudes in the bottom of the D-region of the ionosphere. There, the electron densities in the winter happen to be less than should be expected. On the other hand, the classic winter anomaly is present when in the winter the upper D-region, again at relatively low latitudes, has more ionization than should be expected. Both these effects are due to the slant compression of the geomagnetic field produced by the solar wind in the winter season (which is, of course, the summer season when reference is made to events in the other hemisphere. It is shown that the small winter anomaly is a consequence of a hemispheric imbalance in the flux of galactic cosmic rays determined by the obliquely distorted geomagnetic field. It is shown that the standard winter anomaly can be ascribed to the influx of a super solar wind, which penetrates into the Earth’s polar atmosphere down to E-region heights and, duly concentrated through a funneling action at the winter pole of the distorted geomagnetic field, slows down the winter polar vortex. An equatorward motion of the polar air with its content of nitric oxide brings about the excess of ionization in the upper D-region at lower latitudes. The experimentally observed rhythmic recurrence of the upper winter anomaly is correlated to a possible rhythmic recurrence of the super solar wind. The actual detection of the upper winter anomaly could yield some information on the velocity of the basic solar wind. A by-product of the present analysis, the determination of à , the coefficient of collisional detachment of the electrons from the O2 ions, is presented in the Appendix.

  19. Observations of turbulence and fluctuations in the solar wind

    Energy Technology Data Exchange (ETDEWEB)

    Klein, L.W.

    1987-01-01

    Observational and theoretical studies of turbulent fluctuations in space plasma have been ongoing for many years. There are still many unanswered questions about the origin and evolution of the fluctuations in the heliosphere. This work pursues the subject and uses Voyage 1 and 2, and ISEE-3 measurements to study the evolution of solar-wind plasma and the magnetic field between heliocentric distances of 1 and 20 AU and to more than 25/sup 0/ in latitude above the ecliptic plane. Parker's 1958 solar-wind model is found to be accurate to within 5% in predicting the behavior of long-term (solar rotation) averages in the interplanetary magnetic field when time dependencies in the bulk plasma speed are included. No evidence was found of flux loss in the outer heliosphere as recently reported in the literature. Methods of turbulence analysis and are used to organize the observations and several predictions and expectations of ideal MHD turbulence theory are tested. Spectral indices expected for inertial-range turbulence are present in much of the data analyzed, and this inertial range is found in increasingly larger spatial scales with increasing radial distance from the sun. Evidence for inverse cascade of magnetic helicity is observed in selected intervals, although this was not found to be true in general in the solar wind.

  20. Space Weathering of the Lunar Surface by Solar Wind Particles

    Science.gov (United States)

    Kim, Sungsoo S.; Sim, Chaekyung

    2017-08-01

    The lunar regolith is space-weathered to a different degree in response to the different fluxes of incident solar wind particles and micrometeoroids. Crater walls, among other slating surfaces, are good tracers of the space-weathering process because they mature differently depending on the varying incident angles of weathering agents. We divide a crater wall into four quadrants (north, south, east, and west) and analyze the distribution of 950-nm/750-nm reflectance-ratio and 750-nm reflectance values in each wall quadrant, using the topography-corrected images by Multispectral Imager (MI) onboard SELENE (Kaguya). For thousands of impact craters across the Moon, we interpret the spectral distributions in the four wall quadrants in terms of the space weathering by solar wind particles and micrometeoroids and of gardening by meteroids. We take into account the solar-wind shielding by the Earth’s magnetotail to correctly assess the different spectral behaviors between east- and west-facing walls of the craters in the near-side of the Moon.

  1. Kinetic Physics of the Solar Corona and Solar Wind

    Directory of Open Access Journals (Sweden)

    Marsch Eckart

    2006-07-01

    Full Text Available Kinetic plasma physics of the solar corona and solar wind are reviewed with emphasis on the theoretical understanding of the in situ measurements of solar wind particles and waves, as well as on the remote-sensing observations of the solar corona made by means of ultraviolet spectroscopy and imaging. In order to explain coronal and interplanetary heating, the microphysics of the dissipation of various forms of mechanical, electric and magnetic energy at small scales (e.g., contained in plasma waves, turbulences or non-uniform flows must be addressed. We therefore scrutinise the basic assumptions underlying the classical transport theory and the related collisional heating rates, and also describe alternatives associated with wave-particle interactions. We elucidate the kinetic aspects of heating the solar corona and interplanetary plasma through Landau- and cyclotron-resonant damping of plasma waves, and analyse in detail wave absorption and micro instabilities. Important aspects (virtues and limitations of fluid models, either single- and multi-species or magnetohydrodynamic and multi-moment models, for coronal heating and solar wind acceleration are critically discussed. Also, kinetic model results which were recently obtained by numerically solving the Vlasov–Boltzmann equation in a coronal funnel and hole are presented. Promising areas and perspectives for future research are outlined finally.

  2. Influence of solar wind ions on photoemission charging of dust

    Science.gov (United States)

    Nouzak, Libor; Richterova, Ivana; Pavlu, Jiri; Safrankova, Jana; Nemecek, Zdenek

    2016-04-01

    The lunar surface covered by a layer of dust grains is exposed to solar wind particles and photons coming from the Sun on the sunlit side. Solar wind ions cause sputtering of dust grains or can be implanted into grains. We suppose that as a consequence of ion implantation, an additional energy is transferred to grains, more valence band electrons are excited, and the photoelectron yield is increased. An increase of the photoelectron current causes the enhanced density of electrons that form a sheet above the illuminated lunar surface. Thus, an influence of solar wind ions on the Debye length and photoelectron sheet formation is expected. We present laboratory estimations of work functions and photoelectron yields of a single micron-sized silica grain before and after ion implantation. The silica grain used as a lunar simulant is caught in the electrodynamic trap. Grain's specific charge is evaluated by an analysis of the grain motion within the trap, while its work function is determined from observations of a time evolution of the charge-to-mass ratio when the grain is irradiated by photons of different emission lines. By comparison of the photoelectron current (from grain) with photon flux (from UV source), we establish the photoelectron yield of the trapped object. The influence of ion implantation is thoroughly analyzed and discussed.

  3. Magnetic discontinuities in magnetohydrodynamic turbulence and in the solar wind.

    Science.gov (United States)

    Zhdankin, Vladimir; Boldyrev, Stanislav; Mason, Joanne; Perez, Jean Carlos

    2012-04-27

    Recent measurements of solar wind turbulence report the presence of intermittent, exponentially distributed angular discontinuities in the magnetic field. In this Letter, we study whether such discontinuities can be produced by magnetohydrodynamic (MHD) turbulence. We detect the discontinuities by measuring the fluctuations of the magnetic field direction, Δθ, across fixed spatial increments Δx in direct numerical simulations of MHD turbulence with an imposed uniform guide field B(0). A large region of the probability density function (pdf) for Δθ is found to follow an exponential decay, proportional to exp(-Δθ/θ(*)), with characteristic angle θ(*)≈(14°)(b(rms)/B(0))(0.65) for a broad range of guide-field strengths. We find that discontinuities observed in the solar wind can be reproduced by MHD turbulence with reasonable ratios of b(rms)/B(0). We also observe an excess of small angular discontinuities when Δx becomes small, possibly indicating an increasing statistical significance of dissipation-scale structures. The structure of the pdf in this case closely resembles the two-population pdf seen in the solar wind. We thus propose that strong discontinuities are associated with inertial-range MHD turbulence, while weak discontinuities emerge from dissipation-range turbulence. In addition, we find that the structure functions of the magnetic field direction exhibit anomalous scaling exponents, which indicates the existence of intermittent structures.

  4. Sources of solar wind over the solar activity cycle.

    Science.gov (United States)

    Poletto, Giannina

    2013-05-01

    Fast solar wind has been recognized, about 40 years ago, to originate in polar coronal holes (CHs), that, since then, have been identified with sources of recurrent high speed wind streams. As of today, however, there is no general consensus about whether there are, within CHs, preferential locations where the solar wind is accelerated. Knowledge of slow wind sources is far from complete as well. Slow wind observed in situ can be traced back to its solar source by backward extrapolation of magnetic fields whose field lines are streamlines of the outflowing plasma. However, this technique often has not the necessary precision for an indisputable identification of the region where wind originates. As the Sun progresses through its activity cycle, different wind sources prevail and contribute to filling the heliosphere. Our present knowledge of different wind sources is here summarized. Also, a Section addresses the problem of wind acceleration in the low corona, as inferred from an analysis of UV data, and illustrates changes between fast and slow wind profiles and possible signatures of changes along the solar cycle. A brief reference to recent work about the deep roots of solar wind and their changes over different solar cycles concludes the review.

  5. Invited article: Electric solar wind sail: toward test missions.

    Science.gov (United States)

    Janhunen, P; Toivanen, P K; Polkko, J; Merikallio, S; Salminen, P; Haeggström, E; Seppänen, H; Kurppa, R; Ukkonen, J; Kiprich, S; Thornell, G; Kratz, H; Richter, L; Krömer, O; Rosta, R; Noorma, M; Envall, J; Lätt, S; Mengali, G; Quarta, A A; Koivisto, H; Tarvainen, O; Kalvas, T; Kauppinen, J; Nuottajärvi, A; Obraztsov, A

    2010-11-01

    The electric solar wind sail (E-sail) is a space propulsion concept that uses the natural solar wind dynamic pressure for producing spacecraft thrust. In its baseline form, the E-sail consists of a number of long, thin, conducting, and centrifugally stretched tethers, which are kept in a high positive potential by an onboard electron gun. The concept gains its efficiency from the fact that the effective sail area, i.e., the potential structure of the tethers, can be millions of times larger than the physical area of the thin tethers wires, which offsets the fact that the dynamic pressure of the solar wind is very weak. Indeed, according to the most recent published estimates, an E-sail of 1 N thrust and 100 kg mass could be built in the rather near future, providing a revolutionary level of propulsive performance (specific acceleration) for travel in the solar system. Here we give a review of the ongoing technical development work of the E-sail, covering tether construction, overall mechanical design alternatives, guidance and navigation strategies, and dynamical and orbital simulations.

  6. Construction of Solar-Wind-Like Magnetic Fields

    Science.gov (United States)

    Roberts, Dana Aaron

    2012-01-01

    Fluctuations in the solar wind fields tend to not only have velocities and magnetic fields correlated in the sense consistent with Alfven waves traveling from the Sun, but they also have the magnitude of the magnetic field remarkably constant despite their being broadband. This paper provides, for the first time, a method for constructing fields with nearly constant magnetic field, zero divergence, and with any specified power spectrum for the fluctuations of the components of the field. Every wave vector, k, is associated with two polarizations the relative phases of these can be chosen to minimize the variance of the field magnitude while retaining the\\random character of the fields. The method is applied to a case with one spatial coordinate that demonstrates good agreement with observed time series and power spectra of the magnetic field in the solar wind, as well as with the distribution of the angles of rapid changes (discontinuities), thus showing a deep connection between two seemingly unrelated issues. It is suggested that using this construction will lead to more realistic simulations of solar wind turbulence and of the propagation of energetic particles.

  7. The Spectroscopic Footprint of the Fast Solar Wind

    CERN Document Server

    McIntosh, Scott W; De Pontieu, Bart

    2010-01-01

    We analyze a large, complex equatorial coronal hole (ECH) and its immediate surroundings with a focus on the roots of the fast solar wind. We start by demonstrating that our ECH is indeed a source of the fast solar wind at 1AU by examining in situ plasma measurements in conjunction with recently developed measures of magnetic conditions of the photosphere, inner heliosphere and the mapping of the solar wind source region. We focus the bulk of our analysis on interpreting the thermal and spatial dependence of the non-thermal line widths in the ECH as measured by SOHO/SUMER by placing the measurements in context with recent studies of ubiquitous Alfven waves in the solar atmosphere and line profile asymmetries (indicative of episodic heating and mass loading of the coronal plasma) that originate in the strong, unipolar magnetic flux concentrations that comprise the supergranular network. The results presented in this paper are consistent with a picture where a significant portion of the energy responsible for t...

  8. Geomagnetic response to IMF and solar wind over different latitudes

    Science.gov (United States)

    Aslam, A. M.; Tripathi, Sharad Chandra; Mansoori, Azad Ahmad; Waheed, Malik Abdul

    2016-07-01

    In this paper a study on the response of geomagnetic field characteristics to the solar wind variation during three solar cycles (SC 21, SC 22, SC 23) have been conducted in a long term scale. The difference in the response of two different latitudinal characteristic indices has been investigated. For the purpose we have considered the high latitude index AE and the mid-latitude aa index and both gives the knowledge about the perturbations in the geomagnetic field conditions. Eventually we can infer the idea about the ionospheric current system changes in response to the solar wind conditions. The variation found in the AE and aa indices have been found to follow a 11 year cycle as similar to the sunspot variation. Also the correlation between the annual means of the solar wind parameters velocity V, magnetic filed B and the composite parameters BV and BV ^{2 } have been calculated . A difference was found between the correlations obtained for the AE and aa indices. We could also see that the difference in correlation follows a cyclic pattern i.e. the large difference is found during the solar maxima while a small difference is observed during the minima.

  9. Interaction of the solar wind with comets: a Rosetta perspective.

    Science.gov (United States)

    Glassmeier, Karl-Heinz

    2017-07-13

    The Rosetta mission provides an unprecedented possibility to study the interaction of comets with the solar wind. As the spacecraft accompanies comet 67P/Churyumov-Gerasimenko from its very low-activity stage through its perihelion phase, the physics of mass loading is witnessed for various activity levels of the nucleus. While observations at other comets provided snapshots of the interaction region and its various plasma boundaries, Rosetta observations allow a detailed study of the temporal evolution of the innermost cometary magnetosphere. Owing to the short passage time of the solar wind through the interaction region, plasma instabilities such as ring--beam and non-gyrotropic instabilities are of less importance during the early life of the magnetosphere. Large-amplitude ultra-low-frequency (ULF) waves, the 'singing' of the comet, is probably due to a modified ion Weibel instability. This instability drives a cross-field current of implanted cometary ions unstable. The initial pick-up of these ions causes a major deflection of the solar wind protons. Proton deflection, cross-field current and the instability induce a threefold structure of the innermost interaction region with the characteristic Mach cone and Whistler wings as stationary interaction signatures as well as the ULF waves representing the dynamic aspect of the interaction.This article is part of the themed issue 'Cometary science after Rosetta'. © 2017 The Authors.

  10. Long-Term Trends In The Solar Wind Proton Measurements

    CERN Document Server

    Elliott, Heather A; DeForest, Craig E

    2016-01-01

    We examine the long-term time evolution (1965-2015) of the relationships between solar wind proton temperature (Tp) and speed (Vp) and between the proton density (np) and speed using OMNI solar wind observations taken near Earth. We find a long-term decrease in the proton temperature-speed (Tp-Vp) slope that lasted from 1972 to 2010, but has been trending upward since 2010. Since the solar wind proton density-speed (np-Vp) relationship is not linear like the Tp-Vp relationship, we perform power law fits for np-Vp. The exponent (steepness in the np-Vp relationship) is correlated with the solar cycle. This exponent has a stronger correlation with current sheet tilt angle than with sunspot number because the sunspot number maxima vary considerably from cycle to cycle and the tilt angle maxima do not. To understand this finding, we examined the average np for different speed ranges, and found that for the slow wind np is highly correlated with the sunspot number with a lag of ~4 years. The fast wind np variation ...

  11. Ensemble downscaling in coupled solar wind-magnetosphere modeling for space weather forecasting.

    Science.gov (United States)

    Owens, M J; Horbury, T S; Wicks, R T; McGregor, S L; Savani, N P; Xiong, M

    2014-06-01

    Advanced forecasting of space weather requires simulation of the whole Sun-to-Earth system, which necessitates driving magnetospheric models with the outputs from solar wind models. This presents a fundamental difficulty, as the magnetosphere is sensitive to both large-scale solar wind structures, which can be captured by solar wind models, and small-scale solar wind "noise," which is far below typical solar wind model resolution and results primarily from stochastic processes. Following similar approaches in terrestrial climate modeling, we propose statistical "downscaling" of solar wind model results prior to their use as input to a magnetospheric model. As magnetospheric response can be highly nonlinear, this is preferable to downscaling the results of magnetospheric modeling. To demonstrate the benefit of this approach, we first approximate solar wind model output by smoothing solar wind observations with an 8 h filter, then add small-scale structure back in through the addition of random noise with the observed spectral characteristics. Here we use a very simple parameterization of noise based upon the observed probability distribution functions of solar wind parameters, but more sophisticated methods will be developed in the future. An ensemble of results from the simple downscaling scheme are tested using a model-independent method and shown to add value to the magnetospheric forecast, both improving the best estimate and quantifying the uncertainty. We suggest a number of features desirable in an operational solar wind downscaling scheme.

  12. The New Horizons Solar Wind Around Pluto (SWAP) Observations of the Solar Wind from 11-33 au

    Science.gov (United States)

    Elliott, H. A.; McComas, D. J.; Valek, P.; Nicolaou, G.; Weidner, S.; Livadiotis, G.

    2016-04-01

    The Solar Wind Around Pluto (SWAP) instrument on National Aeronautics and Space Administration's New Horizons Pluto mission has collected solar wind observations en route from Earth to Pluto, and these observations continue beyond Pluto. Few missions have explored the solar wind in the outer heliosphere making this dataset a critical addition to the field. We created a forward model of SWAP count rates, which includes a comprehensive instrument response function based on laboratory and flight calibrations. By fitting the count rates with this model, the proton density (n), speed (V), and temperature (T) parameters are determined. Comparisons between SWAP parameters and both propagated 1 au observations and prior Voyager 2 observations indicate consistency in both the range and mean wind values. These comparisons as well as our additional findings confirm that small and midsized solar wind structures are worn down with increasing distance due to dynamic interaction of parcels of wind with different speed. For instance, the T-V relationship steepens, as the range in V is limited more than the range in T with distance. At times the T-V correlation clearly breaks down beyond 20 au, which may indicate wind currently expanding and cooling may have an elevated T reflecting prior heating and compression in the inner heliosphere. The power of wind parameters at shorter periodicities decreases with distance as the longer periodicities strengthen. The solar rotation periodicity is present in temperature beyond 20 au indicating the observed parcel temperature may reflect not only current heating or cooling, but also heating occurring closer to the Sun.

  13. THE NEW HORIZONS SOLAR WIND AROUND PLUTO (SWAP) OBSERVATIONS OF THE SOLAR WIND FROM 11–33 au

    Energy Technology Data Exchange (ETDEWEB)

    Elliott, H. A.; McComas, D. J.; Valek, P.; Weidner, S.; Livadiotis, G. [Southwest Research Institute, 6220 Culebra Road, San Antonio, TX 78238 (United States); Nicolaou, G., E-mail: helliott@swri.edu [Swedish Institute of Space Physics, Box 812, SE-98128, Kiruna (Sweden)

    2016-04-15

    The Solar Wind Around Pluto (SWAP) instrument on National Aeronautics and Space Administration's New Horizons Pluto mission has collected solar wind observations en route from Earth to Pluto, and these observations continue beyond Pluto. Few missions have explored the solar wind in the outer heliosphere making this dataset a critical addition to the field. We created a forward model of SWAP count rates, which includes a comprehensive instrument response function based on laboratory and flight calibrations. By fitting the count rates with this model, the proton density (n), speed (V), and temperature (T) parameters are determined. Comparisons between SWAP parameters and both propagated 1 au observations and prior Voyager 2 observations indicate consistency in both the range and mean wind values. These comparisons as well as our additional findings confirm that small and midsized solar wind structures are worn down with increasing distance due to dynamic interaction of parcels of wind with different speed. For instance, the T–V relationship steepens, as the range in V is limited more than the range in T with distance. At times the T–V correlation clearly breaks down beyond 20 au, which may indicate wind currently expanding and cooling may have an elevated T reflecting prior heating and compression in the inner heliosphere. The power of wind parameters at shorter periodicities decreases with distance as the longer periodicities strengthen. The solar rotation periodicity is present in temperature beyond 20 au indicating the observed parcel temperature may reflect not only current heating or cooling, but also heating occurring closer to the Sun.

  14. Solar winds surfs waves in the Sun's atmosphere!

    Science.gov (United States)

    1999-07-01

    The fact that this electrified plasma speeds up to almost 3 million kilometres per hour as it leaves the Sun - twice as fast as originally predicted - has been known for years. The interpretation of how it happens is the real and surprising novelty: "The waves in the Sun's atmosphere are produced by vibrating solar magnetic field lines, which give solar wind particles a push just like an ocean wave gives a surfer a ride" said Dr John Kohl, principal investigator for the Ultraviolet Coronal Spectrometer (UVCS) - the instrument among the 12 aboard SOHO which gathered the data - and for the Spartan 201 mission. The outermost solar atmosphere, or corona, is only seen from Earth during a total eclipse of the Sun, when it appears as a shimmering, white veil surrounding the black lunar disc. The corona is an extremely tenuous, electrically charged gas, known as plasma, that flows throughout the solar system as the solar wind. The waves are formed by rapidly vibrating magnetic fields in the coronal plasma. They are called magneto - hydro - dynamic (MHD) waves and are believed to accelerate the solar wind. The solar wind is made up of electrons and ions, electrically charged atoms that have lost electrons. The electric charge of the solar wind particles forces them to travel along invisible lines of magnetic force in the corona. The particles spiral around the magnetic field lines as they rush into space. "The magnetic field acts like a violin string: when it's touched, it vibrates. When the Sun's magnetic field vibrates with a frequency equal to that of the particle spiraling around the magnetic field, it heats it up, producing a force that accelerates the particle upward and away from the Sun," says Dr. Ester Antonucci, an astronomer at the observatory of Turin, Italy, and co-investigator for SOHO's UVCS an instrument developed with considerable financial support by the Italian Space Agency, ASI. In a way this is similar to what happens if two people hold a string at

  15. Anisotropic Solar Wind Sputtering of the Lunar Surface Induced by Crustal Magnetic Anomalies

    Science.gov (United States)

    Poppe, A. R.; Sarantos, M.; Halekas, J. S.; Delory, G. T.; Saito, Y.; Nishino, M.

    2014-01-01

    The lunar exosphere is generated by several processes each of which generates neutral distributions with different spatial and temporal variability. Solar wind sputtering of the lunar surface is a major process for many regolith-derived species and typically generates neutral distributions with a cosine dependence on solar zenith angle. Complicating this picture are remanent crustal magnetic anomalies on the lunar surface, which decelerate and partially reflect the solar wind before it strikes the surface. We use Kaguya maps of solar wind reflection efficiencies, Lunar Prospector maps of crustal field strengths, and published neutral sputtering yields to calculate anisotropic solar wind sputtering maps. We feed these maps to a Monte Carlo neutral exospheric model to explore three-dimensional exospheric anisotropies and find that significant anisotropies should be present in the neutral exosphere depending on selenographic location and solar wind conditions. Better understanding of solar wind/crustal anomaly interactions could potentially improve our results.

  16. Solar-wind and interplanetary electron measurements on the Apollo 15 subsatellite.

    Science.gov (United States)

    Anderson, K. A.; Chase, L. M.; Lin, R. P.; Mcguire, R. E.; Mccoy, J. E.

    1972-01-01

    Measurements of high-energy solar-wind electrons have been made from a low orbit around the moon. Solar-wind electrons can be identified up to energies of about 3000 eV, at which an electron population of entirely different characteristics becomes dominant. The solar-wind cavity on the moon's antisolar side shows evidence of being filled by plasma coming from the downstream direction. When the direction of the interplanetary field corresponds to solar ecliptic azimuth angles of about 90 deg, a partial solar-wind cavity extends across most of the eastern sunlit side of the moon within 20 deg of the moon meridian. There are localized increases in the 500-eV electron flux over much of the sunlit hemisphere. These increases are interpreted to be the result of an interaction between the solar wind and the moon that deflects some of the solar-wind flow and results in limb shocks.

  17. Solar wind helium, neon and argon released by oxidation of metal grains from the Weston chondrite

    Science.gov (United States)

    Becker, R. H.; Rajan, R. S.; Rambaldi, E. R.

    1986-01-01

    A set of experiments were carried out to test the feasibility of determining unfractionated elemental and isotopic ratios for the noble gases in the presumably ancient solar wind present in the gas rich meteorites. The problems of diffusive loss was avoided by analyzing metal rather than the usual silicates. In order to avoid chemical, and even harsh physical, treatment of the sample, which might have affected the surfaces of metal grains, a means of analyzing the metal in the presence of residual silicate not removed by gentle crushing and magnetic separation was devised. Preliminary results given were obtained by taking advantage of the differing properties of metal and silicates with regard to diffusion. The results suggests that, with some modifications in the choice of pyrolysis and combustion temperatures and in the amount of O2 used, it should be possible, by oxidizing the surfaces of metal grains from gas rich meteorites, to obtain data on solar wind that has not been fractionated by diffusive loss.

  18. Characteristics of Solar Wind Density Depletions During Solar Cycles 23 and 24

    Science.gov (United States)

    Park, Keunchan; Lee, Jeongwoo; Yi, Yu; Lee, Jaejin; Sohn, Jongdae

    2017-06-01

    Solar wind density depletions are phenomena that solar wind density is rapidly decreased and keep the state. They are generally believed to be caused by the interplanetary (IP) shocks. However, there are other cases that are hardly associated with IP shocks. We set up a hypothesis for this phenomenon and analyze this study. We have collected the solar wind parameters such as density, speed and interplanetary magnetic field (IMF) data related to the solar wind density depletion events during the period from 1996 to 2013 that are obtained with the advanced composition explorer (ACE) and the Wind satellite. We also calculate two pressures (magnetic, dynamic) and analyze the relation with density depletion. As a result, we found total 53 events and the most these phenomena’s sources caused by IP shock are interplanetary coronal mass ejection (ICME). We also found that solar wind density depletions are scarcely related with IP shock’s parameters. The solar wind density is correlated with solar wind dynamic pressure within density depletion. However, the solar wind density has an little anti-correlation with IMF strength during all events of solar wind density depletion, regardless of the presence of IP shocks. Additionally, In 47 events of IP shocks, we find 6 events that show a feature of blast wave. The quantities of IP shocks are weaker than blast wave from the Sun, they are declined in a short time after increasing rapidly. We thus argue that IMF strength or dynamic pressure are an important factor in understanding the nature of solar wind density depletion. Since IMF strength and solar wind speed varies with solar cycle, we will also investigate the characteristics of solar wind density depletion events in different phases of solar cycle as an additional clue to their physical nature.

  19. The influence of solar wind variability on magnetospheric ULF wave power

    Energy Technology Data Exchange (ETDEWEB)

    Pokhotelov, D.; Rae, I.J. [UCL, Dorking (United Kingdom). Mullard Space Science Lab.; Murphy, K.R. [NASA Goddard Space Flight Center, Greenbelt, MD (United States); Mann, I.R. [Alberta Univ., Edmonton, AB (Canada). Dept. of Physics

    2015-10-01

    Magnetospheric ultra-low frequency (ULF) oscillations in the Pc 4-5 frequency range play an important role in the dynamics of Earth's radiation belts, both by enhancing the radial diffusion through incoherent interactions and through the coherent drift-resonant interactions with trapped radiation belt electrons. The statistical distributions of magnetospheric ULF wave power are known to be strongly dependent on solar wind parameters such as solar wind speed and interplanetary magnetic field (IMF) orientation. Statistical characterisation of ULF wave power in the magnetosphere traditionally relies on average solar wind-IMF conditions over a specific time period. In this brief report, we perform an alternative characterisation of the solar wind influence on magnetospheric ULF wave activity through the characterisation of the solar wind driver by its variability using the standard deviation of solar wind parameters rather than a simple time average. We present a statistical study of nearly one solar cycle (1996-2004) of geosynchronous observations of magnetic ULF wave power and find that there is significant variation in ULF wave powers as a function of the dynamic properties of the solar wind. In particular, we find that the variability in IMF vector, rather than variabilities in other parameters (solar wind density, bulk velocity and ion temperature), plays the strongest role in controlling geosynchronous ULF power. We conclude that, although time-averaged bulk properties of the solar wind are a key factor in driving ULF powers in the magnetosphere, the solar wind variability can be an important contributor as well. This highlights the potential importance of including solar wind variability especially in studies of ULF wave dynamics in order to assess the efficiency of solar wind-magnetosphere coupling.

  20. Kinetic scale turbulence and dissipation in the solar wind: key observational results and future outlook.

    Science.gov (United States)

    Goldstein, M L; Wicks, R T; Perri, S; Sahraoui, F

    2015-05-13

    Turbulence is ubiquitous in the solar wind. Turbulence causes kinetic and magnetic energy to cascade to small scales where they are eventually dissipated, adding heat to the plasma. The details of how this occurs are not well understood. This article reviews the evidence for turbulent dissipation and examines various diagnostics for identifying solar wind regions where dissipation is occurring. We also discuss how future missions will further enhance our understanding of the importance of turbulence to solar wind dynamics.

  1. Earth's magnetosphere and outer radiation belt under sub-Alfvénic solar wind.

    Science.gov (United States)

    Lugaz, Noé; Farrugia, Charles J; Huang, Chia-Lin; Winslow, Reka M; Spence, Harlan E; Schwadron, Nathan A

    2016-10-03

    The interaction between Earth's magnetic field and the solar wind results in the formation of a collisionless bow shock 60,000-100,000 km upstream of our planet, as long as the solar wind fast magnetosonic Mach (hereafter Mach) number exceeds unity. Here, we present one of those extremely rare instances, when the solar wind Mach number reached steady values solar wind-magnetosphere coupling which is unusual for planets in our solar system but may be common for close-in extrasolar planets.

  2. About the correlation between solar micro bursts and the change of the solar wind parameters

    OpenAIRE

    Oliveros, Juan Carlos Martinez; P, Daniel Ricardo Izquierdo

    2005-01-01

    The Sun is the closest star to our planet and it is the most studied, perhaps, there exist too much procesess not-understood. One of the solar processes that have a direct interaction with the earth is the solar wind. The solar wind is defined as the plasma expulsed from the solar atmosphere, this wind was cataloged and is considered that have three components: - Passive solar wind: Is the constant component of the solar wind. - Supersonic and quasistady flux. - Sporadic supersonic flux. We p...

  3. Solar Wind Sputtering of Lunar Soil Analogs: The Effect of Ionic Charge and Mass

    Science.gov (United States)

    Hijazi, H.; Bannister, M. E.; Meyer, F. W.; Rouleau, C. M.; Barghouty, A. F.; Rickman, D. L.; Hijazi, H.

    2014-01-01

    In this contribution we report sput-tering measurements of anorthite, an analog material representative of the lunar highlands, by singly and multicharged ions representative of the solar wind. The ions investigated include protons, as well as singly and multicharged Ar ions (as proxies for the heavier solar wind constituents), in the charge state range +1 to +9, and had a fixed solar-wind-relevant impact velocity of approximately 310 km/s or 500 eV/ amu. The goal of the measurements was to determine the sputtering contribution of the heavy, multicharged minority solar wind constituents in comparison to that due to the dominant H+ fraction.

  4. Solar wind dynamic pressure and electric field as the main factors controlling Saturn's aurorae.

    Science.gov (United States)

    Crary, F J; Clarke, J T; Dougherty, M K; Hanlon, P G; Hansen, K C; Steinberg, J T; Barraclough, B L; Coates, A J; Gérard, J-C; Grodent, D; Kurth, W S; Mitchell, D G; Rymer, A M; Young, D T

    2005-02-17

    The interaction of the solar wind with Earth's magnetosphere gives rise to the bright polar aurorae and to geomagnetic storms, but the relation between the solar wind and the dynamics of the outer planets' magnetospheres is poorly understood. Jupiter's magnetospheric dynamics and aurorae are dominated by processes internal to the jovian system, whereas Saturn's magnetosphere has generally been considered to have both internal and solar-wind-driven processes. This hypothesis, however, is tentative because of limited simultaneous solar wind and magnetospheric measurements. Here we report solar wind measurements, immediately upstream of Saturn, over a one-month period. When combined with simultaneous ultraviolet imaging we find that, unlike Jupiter, Saturn's aurorae respond strongly to solar wind conditions. But in contrast to Earth, the main controlling factor appears to be solar wind dynamic pressure and electric field, with the orientation of the interplanetary magnetic field playing a much more limited role. Saturn's magnetosphere is, therefore, strongly driven by the solar wind, but the solar wind conditions that drive it differ from those that drive the Earth's magnetosphere.

  5. Solar wind modulation of the Martian ionosphere observed by Mars Global Surveyor

    Directory of Open Access Journals (Sweden)

    J.-S. Wang

    2004-06-01

    Full Text Available Electron density profiles in the Martian ionosphere observed by the radio occultation experiment on board Mars Global Surveyor have been analyzed to determine if the densities are influenced by the solar wind. Evidence is presented that the altitude of the maximum ionospheric electron density shows a positive correlation to the energetic proton flux in the solar wind. The solar wind modulation of the Martian ionosphere can be attributed to heating of the neutral atmosphere by the solar wind energetic proton precipitation. The modulation is observed to be most prominent at high solar zenith angles. It is argued that this is consistent with the proposed modulation mechanism.

  6. Structure, dynamics, and seasonal variability of the Mars-solar wind interaction: MAVEN Solar Wind Ion Analyzer in-flight performance and science results

    Science.gov (United States)

    Halekas, J. S.; Ruhunusiri, S.; Harada, Y.; Collinson, G.; Mitchell, D. L.; Mazelle, C.; McFadden, J. P.; Connerney, J. E. P.; Espley, J. R.; Eparvier, F.; Luhmann, J. G.; Jakosky, B. M.

    2017-01-01

    We report on the in-flight performance of the Solar Wind Ion Analyzer (SWIA) and observations of the Mars-solar wind interaction made during the Mars Atmosphere and Volatile EvolutioN (MAVEN) prime mission and a portion of its extended mission, covering 0.85 Martian years. We describe the data products returned by SWIA and discuss the proper handling of measurements made with different mechanical attenuator states and telemetry modes, and the effects of penetrating and scattered backgrounds, limited phase space coverage, and multi-ion populations on SWIA observations. SWIA directly measures solar wind protons and alpha particles upstream from Mars. SWIA also provides proxy measurements of solar wind and neutral densities based on products of charge exchange between the solar wind and the hydrogen corona. Together, upstream and proxy observations provide a complete record of the solar wind experienced by Mars, enabling organization of the structure, dynamics, and ion escape from the magnetosphere. We observe an interaction that varies with season and solar wind conditions. Solar wind dynamic pressure, Mach number, and extreme ultraviolet flux all affect the bow shock location. We confirm the occurrence of order-of-magnitude seasonal variations of the hydrogen corona. We find that solar wind Alfvén waves, which provide an additional energy input to Mars, vary over the mission. At most times, only weak mass loading occurs upstream from the bow shock. However, during periods with near-radial interplanetary magnetic fields, structures consistent with Short Large Amplitude Magnetic Structures and their wakes form upstream, dramatically reconfiguring the Martian bow shock and magnetosphere.

  7. OMNI: A Description of Near-Earth Solar Wind Environment

    Science.gov (United States)

    Papitashvili, Natasha; Bilitza, Dieter; King, Joseph

    OMNI is an hourly resolution multi-source data set of near-Earth solar wind's magnetic field and plasma parameters spanning the period from November 1963 (IMP 1 launch) to today, and it is being updated regularly with new data. OMNI is widely used in the heliospheric community as is documented by the large number of acknowledgements in scientific papers. OMNI provides the IMF (magnitude and vector), flow velocity (magnitude and vector), flow pressure, proton density, alpha particle to proton density ratio, and several additional parameters including sunspot and geomagnetic indices and energetic proton fluxes from IMP and GOES. Spacecraft data used for compiling the OMNI solar wind reference include IMP-8, ACE, Wind, ISEE-3, and Geotail. The data from ISEE-3, Wind, and ACE were time-shifted because they are about an hour upstream of the Earth's magnetosphere. Extensive quality control and cross- comparisons of overlapping data sets were made in creating OMNI. This presentation will describe the OMNI data set and highlight its wide use in the space science community. We will also present some of the many capabilities of the OMNIweb interface (http://omniweb.gsfc.nasa.gov/ow.html) that provides access to the entire OMNI data set. OMNIWeb allows users to generate plots vs. time, to create scatter plots of any two OMNI parameters, to filter with user-specified parameter range criteria, to list and download OMNI parameters, to generate distributions of OMNI parameter values, and to browse and retrieve a static (but periodically updated) daily-resolution IMF polarity plot covering the entire OMNI time span. The Omni data set represents a thorough description of various characteristics of near-Earth solar wind magnetic field and plasma, which could be used as a basis for that space environment's standard.

  8. A Model fot the Sources of the Slow Solar Wind

    Science.gov (United States)

    Antiochos, S. K.; Mikic, Z.; Titov, V. S.; Lionello, R.; Linker, J. A.

    2011-01-01

    Models for the origin of the slow solar wind must account for two seemingly contradictory observations: the slow wind has the composition of the closed-field corona, implying that it originates from the continuous opening and closing of flux at the boundary between open and closed field. On the other hand, the slow wind also has large angular width, up to approx.60deg, suggesting that its source extends far from the open-closed boundary. We propose a model that can explain both observations. The key idea is that the source of the slow wind at the Sun is a network of narrow (possibly singular) open-field corridors that map to a web of separatrices and quasi-separatrix layers in the heliosphere. We compute analytically the topology of an open-field corridor and show that it produces a quasi-separatrix layer in the heliosphere that extends to angles far from the heliospheric current sheet. We then use an MHD code and MDI/SOHO observations of the photospheric magnetic field to calculate numerically, with high spatial resolution, the quasi-steady solar wind, and magnetic field for a time period preceding the 2008 August 1 total solar eclipse. Our numerical results imply that, at least for this time period, a web of separatrices (which we term an S-web) forms with sufficient density and extent in the heliosphere to account for the observed properties of the slow wind. We discuss the implications of our S-web model for the structure and dynamics of the corona and heliosphere and propose further tests of the model. Key words: solar wind - Sun: corona - Sun: magnetic topology

  9. Line Ratios for Solar Wind Charge Exchange with Comets

    Science.gov (United States)

    Mullen, P. D.; Cumbee, R. S.; Lyons, D.; Gu, L.; Kaastra, J.; Shelton, R. L.; Stancil, P. C.

    2017-07-01

    Charge exchange (CX) has emerged in X-ray emission modeling as a significant process that must be considered in many astrophysical environments—particularly comets. Comets host an interaction between solar wind ions and cometary neutrals to promote solar wind charge exchange (SWCX). X-ray observatories provide astronomers and astrophysicists with data for many X-ray emitting comets that are impossible to accurately model without reliable CX data. Here, we utilize a streamlined set of computer programs that incorporate the multi-channel Landau-Zener theory and a cascade model for X-ray emission to generate cross sections and X-ray line ratios for a variety of bare and non-bare ion single electron capture (SEC) collisions. Namely, we consider collisions between the solar wind constituent bare and H-like ions of C, N, O, Ne, Na, Mg, Al, and Si and the cometary neutrals H2O, CO, CO2, OH, and O. To exemplify the application of this data, we model the X-ray emission of Comet C/2000 WM1 (linear) using the CX package in SPEX and find excellent agreement with observations made with the XMM-Newton RGS detector. Our analyses show that the X-ray intensity is dominated by SWCX with H, while H2O plays a secondary role. This is the first time, to our knowledge, that CX cross sections have been implemented into a X-ray spectral fitting package to determine the H to H2O ratio in cometary atmospheres. The CX data sets are incorporated into the modeling packages SPEX and Kronos.

  10. The Statistical Mechanics of Solar Wind Hydroxylation at the Moon, Within Lunar Magnetic Anomalies, and at Phobos

    Science.gov (United States)

    Farrell, W. M.; Hurley, D. M.; Esposito, V. J.; Mclain, J. L.; Zimmerman, M. I.

    2017-01-01

    We present a new formalism to describe the outgassing of hydrogen initially implanted by the solar wind protons into exposed soils on airless bodies. The formalism applies a statistical mechanics approach similar to that applied recently to molecular adsorption onto activated surfaces. The key element enabling this formalism is the recognition that the interatomic potential between the implanted H and regolith-residing oxides is not of singular value but possess a distribution of trapped energy values at a given temperature, F(U,T). All subsequent derivations of the outward diffusion and H retention rely on the specific properties of this distribution. We find that solar wind hydrogen can be retained if there are sites in the implantation layer with activation energy values exceeding 0.5eV. We especially examine the dependence of H retention applying characteristic energy values found previously for irradiated silica and mature lunar samples. We also apply the formalism to two cases that differ from the typical solar wind implantation at the Moon. First, we test for a case of implantation in magnetic anomaly regions where significantly lower-energy ions of solar wind origin are expected to be incident with the surface. In magnetic anomalies, H retention is found to be reduced due to the reduced ion flux and shallower depth of implantation. Second, we also apply the model to Phobos where the surface temperature range is not as extreme as the Moon. We find the H atom retention in this second case is higher than the lunar case due to the reduced thermal extremes (that reduces outgassing).

  11. The statistical mechanics of solar wind hydroxylation at the Moon, within lunar magnetic anomalies, and at Phobos

    Science.gov (United States)

    Farrell, W. M.; Hurley, D. M.; Esposito, V. J.; McLain, J. L.; Zimmerman, M. I.

    2017-01-01

    We present a new formalism to describe the outgassing of hydrogen initially implanted by the solar wind protons into exposed soils on airless bodies. The formalism applies a statistical mechanics approach similar to that applied recently to molecular adsorption onto activated surfaces. The key element enabling this formalism is the recognition that the interatomic potential between the implanted H and regolith-residing oxides is not of singular value but possess a distribution of trapped energy values at a given temperature, F(U,T). All subsequent derivations of the outward diffusion and H retention rely on the specific properties of this distribution. We find that solar wind hydrogen can be retained if there are sites in the implantation layer with activation energy values exceeding 0.5 eV. We especially examine the dependence of H retention applying characteristic energy values found previously for irradiated silica and mature lunar samples. We also apply the formalism to two cases that differ from the typical solar wind implantation at the Moon. First, we test for a case of implantation in magnetic anomaly regions where significantly lower-energy ions of solar wind origin are expected to be incident with the surface. In magnetic anomalies, H retention is found to be reduced due to the reduced ion flux and shallower depth of implantation. Second, we also apply the model to Phobos where the surface temperature range is not as extreme as the Moon. We find the H atom retention in this second case is higher than the lunar case due to the reduced thermal extremes (that reduces outgassing).

  12. Solar wind influences on atmospheric electricity variables in polar regions

    Science.gov (United States)

    Michnowski, Stanisław

    The measurement techniques applied in magnetospheric and ionospheric research enable detection of strong, intrinsic effects of solar wind on ionospheric electrical potential distribution and conductivity of the atmosphere. These manifestations of the solar wind interaction with the magnetosphere and ionosphere are especially evident at high latitudes. The possibility of observing there the response of the atmospheric electricity variables to solar wind has been questioned for a long time despite the fact that the atmospheric electric field and current variations at the ground are physically linked with electric potential of the ionosphere and conductivity of the lower atmosphere. The serious doubts were mainly due to the generally accepted opinion that the highly conducting ionosphere is an almost ideal equipotential electric screen that separates the weakly conductive lower atmosphere of the influence from space. This assumption could not be further upheld in view of the new findings. They have been provided for some time by ground-based atmospheric electric field and current measurements (AEMs) with simultaneous upper atmosphere observations and by corresponding balloon measurements. Recent ground-based AEMs in polar regions, i.e., in the near-subauroral, auroral, and polar cap high-latitude regions, have detected considerable influence of solar wind on the lower-atmosphere electric variables. However, the use of atmospheric electric observations in studying solar-terrestrial relations is still limited. The main reason is difficulty in separating various local meteorological effects, anthropogenic effects, and the effects of the global electric current circuit which affect simultaneously the measured quantities. Transmission of the electric signals through the lower atmosphere can also introduce troublesome disturbances. The paper outlines these problems and hints how the difficulties involved might be partly overcome in a feasible way. The needs and possible

  13. The Nature of Subproton Scale Turbulence in the Solar Wind

    CERN Document Server

    Chen, C H K; Xia, Q; Perez, J C

    2013-01-01

    The nature of subproton scale fluctuations in the solar wind is an open question, partly because two similar types of electromagnetic turbulence can occur: kinetic Alfven turbulence and whistler turbulence. These two possibilities, however, have one key qualitative difference: whistler turbulence, unlike kinetic Alfven turbulence, has negligible power in density fluctuations. In this Letter, we present new observational data, as well as analytical and numerical results, to investigate this difference. The results show, for the first time, that the fluctuations well below the proton scale are predominantly kinetic Alfven turbulence, and, if present at all, the whistler fluctuations make up only a small fraction of the total energy.

  14. Linear magnetosonic waves in solar wind flow tubes

    OpenAIRE

    2010-01-01

    Nakariakov et al. (1996) investigated the linear magnetosonic waves trapped within solar wind flow tubes, where they accounted for a slab having boundaries at $x = \\pm d$ and extended up to infinity in the $y$ and $z$ directions. Srivastava and Dwivedi (2006) claimed to extend that work by considering a two-dimensional slab. We find that the work of Srivastava and Dwivedi (2006) is not for a two-dimensional slab and has a number of discrepancies. Further, their results for body waves are not ...

  15. Transport of Solar Wind Fluctuations: A Two-Component Model

    Science.gov (United States)

    Oughton, S.; Matthaeus, W. H.; Smith, C. W.; Breech, B.; Isenberg, P. A.

    2011-01-01

    We present a new model for the transport of solar wind fluctuations which treats them as two interacting incompressible components: quasi-two-dimensional turbulence and a wave-like piece. Quantities solved for include the energy, cross helicity, and characteristic transverse length scale of each component, plus the proton temperature. The development of the model is outlined and numerical solutions are compared with spacecraft observations. Compared to previous single-component models, this new model incorporates a more physically realistic treatment of fluctuations induced by pickup ions and yields improved agreement with observed values of the correlation length, while maintaining good observational accord with the energy, cross helicity, and temperature.

  16. Solar wind driven dust acoustic instability with Lorentzian kappa distribution

    Energy Technology Data Exchange (ETDEWEB)

    Arshad, Kashif [National Center for Physics (NCP), Quaid-i-Azam University Campus, Shahdra Valley Road, Islamabad 44000 (Pakistan); Pakistan Institute of Engineering and Applied Sciences, P.O. Nilore, Islamabad and University of Wah, Wah Cantt 47040 (Pakistan); Ehsan, Zahida, E-mail: Ehsan.zahida@gmail.com [National Center for Physics (NCP), Quaid-i-Azam University Campus, Shahdra Valley Road, Islamabad 44000 (Pakistan); Universita degli Studi del Molise, 86090 Pesche - IS (Italy); INFN Sezione di Napoli, 80126 Napoli (Italy); Department of Physics, COMSATS Institute of Information Technology (CIIT), Defence Road, Off Raiwind Road, Lahore 86090 (Pakistan); Khan, S. A. [National Center for Physics (NCP), Quaid-i-Azam University Campus, Shahdra Valley Road, Islamabad 44000 (Pakistan); Mahmood, S. [Theoretical Plasma Physics Division, PINSTEC, PO Box Nilore, Islamabad 44000 (Pakistan)

    2014-02-15

    In a three species electron-ion-dust plasma following a generalized non-Maxwellian distribution function (Lorentzian or kappa), it is shown that a kinetic instability of dust-acoustic mode exists. The instability threshold is affected when such (quasineutral) plasma permeates through another static plasma. Such case is of interest when the solar wind is streaming through the cometary plasma in the presence of interstellar dust. In the limits of phase velocity of the waves larger and smaller than the thermal velocity of dust particles, the dispersion properties and growth rate of dust-acoustic mode are investigated analytically with validation via numerical analysis.

  17. Generalized similarity in finite range solar wind magnetohydrodynamic turbulence.

    Science.gov (United States)

    Chapman, S C; Nicol, R M

    2009-12-11

    Extended or generalized similarity is a ubiquitous but not well understood feature of turbulence that is realized over a finite range of scales. The ULYSSES spacecraft solar polar passes at solar minimum provide in situ observations of evolving anisotropic magnetohydrodynamic turbulence in the solar wind under ideal conditions of fast quiet flow. We find a single generalized scaling function characterizes this finite range turbulence and is insensitive to plasma conditions. The recent unusually inactive solar minimum--with turbulent fluctuations down by a factor of approximately 2 in power--provides a test of this invariance.

  18. Isotropic Scale-Invariant Dissipation of Solar Wind Turbulence

    CERN Document Server

    Kiyani, K H; Khotyaintsev, Yu V; Turner, A; Hnat, B; Sahraoui, F

    2010-01-01

    The anisotropic nature of solar wind magnetic fluctuations is investigated scale-by-scale using high cadence in-situ magnetic field measurements spanning five decades in scales from the inertial to dissipation ranges of plasma turbulence. We find an abrupt transition at ion kinetic scales to a single isotropic stochastic process that characterizes the dissipation range on all observable scales. In contrast to the inertial range, this is accompanied by a successive scale-invariant reduction in the ratio between parallel and transverse power. We suggest a possible phase space mechanism for this, based on nonlinear wave-particle interactions, operating in this scale-invariant isotropic manner.

  19. Assessing temporal complementarity of solar, wind and hydrokinetic energy

    Directory of Open Access Journals (Sweden)

    Jurasz Jakub

    2016-01-01

    Full Text Available Renewable energy sources (RES exhibit various characteristics when it comes to their availability in time and space domain. Some are characterised by significant variability and limited predictability. This makes their integration to the power grid a complicated task. Temporal and spatial complementarity of RES is perceived as one of the possible ways to facilitate the process of integration. This paper investigates the concept of temporal complementarity of solar wind and hydrokinetic energy in case of two sites in Poland. Obtained results indicate existence of some beneficial complementarity on inter-annual and annual time scale. Combination of those three RES in one hybrid system makes power source more reliable.

  20. Multiscale nature of the dissipation range in solar wind turbulence

    CERN Document Server

    Told, D; TenBarge, J M; Howes, G G; Hammett, G W

    2015-01-01

    Nonlinear energy transfer and dissipation in Alfv\\'en wave turbulence are analyzed in the first gyrokinetic simulation spanning all scales from the tail of the MHD range to the electron gyroradius scale. For typical solar wind parameters at 1 AU, about 30% of the nonlinear energy transfer close to the electron gyroradius scale is mediated by modes in the tail of the MHD cascade. Collisional dissipation occurs across the entire kinetic range $k_\\perp\\rho_i\\gtrsim 1$. Both mechanisms thus act on multiple coupled scales, which have to be retained for a comprehensive picture of the dissipation range in Alfv\\'enic turbulence.

  1. Martian ionosphere response to solar wind variability during solar minimum

    Science.gov (United States)

    Sanchez-Cano, Beatriz; Lester, Mark; Witasse, Olivier; Mays, M. Leila; Hall, Benjamin E. S.; Milan, Stephen E.; Cartacci, Marco; Blelly, Pierre-Louis; Andrews, David; Opgenoorth, Hermann; Odstrcil, Dusan

    2016-04-01

    Solar cycle variations in solar radiation create notable density changes in the Martian ionosphere. In addition to this long-term variability, there are numerous short-term and non-recurrent solar events that hit Mars which need to be considered, such as Interplanetary Coronal Mass Ejections (ICMEs), Co-Rotation Interaction Regions (CIRs), solar flares, or solar wind high speed streams. The response of the Martian plasma system to each of these events is often unusual, especially during the long period of extreme low solar activity in 2008 and 2009. This work shows the long-term solar cycle impact on the ionosphere of Mars using data from The Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS), and The Analyzer of Space Plasma and Energetic Atoms (ASPERA-3), and with empirical and numerical models on Mars Express. Particular attention is given to the different ionospheric responses observed during the last, extended solar minimum. Mars' ionospheric response followed a similar pattern to the response observed in the Earth's ionosphere, despite the large differences related to the inner-origin of the magnetic field of both planets. The ionospheric temperature was cooler, the topside scale height was smaller and almost constant with altitude, the secondary ionospheric layer practically disappeared and the whole atmospheric total electron content (TEC) suffered an extreme reduction of about 30-40%, not predicted before by models. Moreover, there is a larger probability for the induced magnetic field to be present in the ionosphere, than in other phases of the solar cycle. The short-term variability is also addressed with the study of an ICME followed by a fast stream that hit Mars in March 2008, where solar wind data are provided by ACE and STEREO-B and supported by simulations using the WSA-ENLIL Model. The solar wind conditions lead to the formation of a CIR centred on the interface of the fast and the slow solar wind streams. Mars' system reacted to

  2. Solar Wind Interaction and Impact on the Venus Atmosphere

    Science.gov (United States)

    Futaana, Yoshifumi; Stenberg Wieser, Gabriella; Barabash, Stas; Luhmann, Janet G.

    2017-08-01

    Venus has intrigued planetary scientists for decades because of its huge contrasts to Earth, in spite of its nickname of "Earth's Twin". Its invisible upper atmosphere and space environment are also part of the larger story of Venus and its evolution. In 60s to 70s, several missions (Venera and Mariner series) explored Venus-solar wind interaction regions. They identified the basic structure of the near-Venus space environment, for example, existence of the bow shock, magnetotail, ionosphere, as well as the lack of the intrinsic magnetic field. A huge leap in knowledge about the solar wind interaction with Venus was made possible by the 14-year long mission, Pioneer Venus Orbiter (PVO), launched in 1978. More recently, ESA's probe, Venus Express (VEX), was inserted into orbit in 2006, operated for 8 years. Owing to its different orbit from that of PVO, VEX made unique measurements in the polar and terminator regions, and probed the near-Venus tail for the first time. The near-tail hosts dynamic processes that lead to plasma energization. These processes in turn lead to the loss of ionospheric ions to space, slowly eroding the Venusian atmosphere. VEX carried an ion spectrometer with a moderate mass-separation capability and the observed ratio of the escaping hydrogen and oxygen ions in the wake indicates the stoichiometric loss of water from Venus. The structure and dynamics of the induced magnetosphere depends on the prevailing solar wind conditions. VEX studied the response of the magnetospheric system on different time scales. A plethora of waves was identified by the magnetometer on VEX; some of them were not previously observed by PVO. Proton cyclotron waves were seen far upstream of the bow shock, mirror mode waves were observed in magnetosheath and whistler mode waves, possibly generated by lightning discharges were frequently seen. VEX also encouraged renewed numerical modeling efforts, including fluid-type of models and particle-fluid hybrid type of models

  3. Using the fingerprints of solar magnetic reconnection to identify the elemental building blocks of the slow solar wind

    Science.gov (United States)

    Kepko, Larry; Viall, Nicholeen M.; Kasper, Justin; Lepri, Sue

    2015-04-01

    While the source of the fast solar wind is well understood to be linked to coronal holes, the source of the slow solar wind has remained elusive. Many previous studies of the slow solar wind have examined trends in the composition and charge states over long time scales and found strong relationships between the solar wind velocity and these plasma parameters. These relationships have been used to constrain models of solar wind source and acceleration. In this study, we take advantage of high time resolution (12 min) measurements of solar wind composition and charge-state abundances recently reprocessed by the ACE Solar Wind Ion Composition Spectrometer (SWICS) science team to probe the timescales of solar wind variability at relatively small scales. We study an interval of slow solar wind containing quasi-periodic 90 minute structures and show that they are remnants of solar magnetic reconnection. Each 90-minute parcel of slow solar wind, though the speed remains steady, exhibits the complete range of charge state and composition variations expected for the entire range of slow solar wind, which is repeated again in the next 90-minute interval. These observations show that previous statistical results break down on these shorter timescales, and impose new and important constraints on models of slow solar wind creation. We conclude by suggesting these structures were created through interchange magnetic reconnection and form elemental building blocks of the slow solar wind. We also discuss the necessity of decoupling separately the process(es) responsible for the release and acceleration.

  4. Genesis machines

    CERN Document Server

    Amos, Martyn

    2014-01-01

    Silicon chips are out. Today's scientists are using real, wet, squishy, living biology to build the next generation of computers. Cells, gels and DNA strands are the 'wetware' of the twenty-first century. Much smaller and more intelligent, these organic computers open up revolutionary possibilities. Tracing the history of computing and revealing a brave new world to come, Genesis Machines describes how this new technology will change the way we think not just about computers - but about life itself.

  5. On Genesis

    Directory of Open Access Journals (Sweden)

    Louis Althusser

    2012-01-01

    Full Text Available On Genesis, written In 1966 is a short summary of Althusser’s earlytheory of encounter. In Althusser’s note we find description of structural causalityas opposed to teleological and mechanicist notions of historical determinations. Thetext has documentary value allowing the reader to look at problems presented insuch works as Reading Capital from the perspective proposed by Aalthusser in histexts devoted, among others, to aleatory conception of materialism and theory ofhistory.

  6. Solar wind implication on dust ion acoustic rogue waves

    Energy Technology Data Exchange (ETDEWEB)

    Abdelghany, A. M., E-mail: asmaaallah20@yahoo.com; Abd El-Razek, H. N., E-mail: hosam.abdelrazek@yahoo.com; El-Labany, S. K., E-mail: skellabany@hotmail.com [Theoretical Physics Group, Department of Physics, Faculty of Science, Damietta University, New Damietta 34517 (Egypt); Moslem, W. M., E-mail: wmmoslem@hotmail.com [Department of Physics, Faculty of Science, Port Said University, Port Said 42521 (Egypt); Centre for Theoretical Physics, The British University in Egypt (BUE), El-Shorouk City, Cairo (Egypt)

    2016-06-15

    The relevance of the solar wind with the magnetosphere of Jupiter that contains positively charged dust grains is investigated. The perturbation/excitation caused by streaming ions and electron beams from the solar wind could form different nonlinear structures such as rogue waves, depending on the dominant role of the plasma parameters. Using the reductive perturbation method, the basic set of fluid equations is reduced to modified Korteweg-de Vries (KdV) and further modified (KdV) equation. Assuming that the frequency of the carrier wave is much smaller than the ion plasma frequency, these equations are transformed into nonlinear Schrödinger equations with appropriate coefficients. Rational solution of the nonlinear Schrödinger equation shows that rogue wave envelopes are supported by the present plasma model. It is found that the existence region of rogue waves depends on the dust-acoustic speed and the streaming temperatures for both the ions and electrons. The dependence of the maximum rogue wave envelope amplitude on the system parameters has been investigated.

  7. Observations and Simulations of Magnetohydrodynamic Turbulence in the Solar Wind

    Science.gov (United States)

    Goldstein, M. L.

    2006-12-01

    Alfvénic fluctuations are a ubiquitous component of the solar wind. Evidence from many spacecraft indicates that the fluctuations are convected out of the solar corona with relatively flat power spectra and constitute a source of free energy for a turbulent cascade of magnetic and kinetic energy to high wave numbers. Observations and simulations support the conclusion that the cascade evolves most rapidly in the vicinity of velocity shears and current sheets. Numerical solutions of the magnetohydrodynamic equations have elucidated the role of expansion on the evolution of the turbulence. Such studies are clarifying not only how a turbulent cascade develops, but also the nature of the symmetries of the turbulence. Of particular interest is the origin of the two-component correlation function of magnetic fluctuations that was deduced from ISEE-3 data. A central issue to be resolved is whether the correlation function indicates the existence of a quasi-two- dimensional component of the turbulence, or reflects another origin, such as pressure-balanced structures or small velocity shears. In our efforts to simulate solar wind turbulence we have included a tilted rotating current heliospheric sheet as well as variety of waves (e.g., Alfvénic, quasi-two-dimensional, pressure balance structures) and microstreams. These simulations have replicated many of the observations, but challenges remain.

  8. STEADY-STATE MODEL OF SOLAR WIND ELECTRONS REVISITED

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Peter H.; Kim, Sunjung; Choe, G. S., E-mail: yoonp@umd.edu [School of Space Research, Kyung Hee University, Yongin, Gyeonggi 446-701 (Korea, Republic of)

    2015-10-20

    In a recent paper, Kim et al. put forth a steady-state model for the solar wind electrons. The model assumed local equilibrium between the halo electrons, characterized by an intermediate energy range, and the whistler-range fluctuations. The basic wave–particle interaction is assumed to be the cyclotron resonance. Similarly, it was assumed that a dynamical steady state is established between the highly energetic superhalo electrons and high-frequency Langmuir fluctuations. Comparisons with the measured solar wind electron velocity distribution function (VDF) during quiet times were also made, and reasonable agreements were obtained. In such a model, however, only the steady-state solution for the Fokker–Planck type of electron particle kinetic equation was considered. The present paper complements the previous analysis by considering both the steady-state particle and wave kinetic equations. It is shown that the model halo and superhalo electron VDFs, as well as the assumed wave intensity spectra for the whistler and Langmuir fluctuations, approximately satisfy the quasi-linear wave kinetic equations in an approximate sense, thus further validating the local equilibrium model constructed in the paper by Kim et al.

  9. STRAHL FORMATION IN THE SOLAR WIND ELECTRONS VIA WHISTLER INSTABILITY

    Energy Technology Data Exchange (ETDEWEB)

    Seough, Jungjoon; Nariyuki, Yasuhiro [Faculty of Human Development, University of Toyama, 3190, Gofuku, Toyama City, Toyama 930-8555 (Japan); Yoon, Peter H. [Institute for Physical Science and Technology, University of Maryland, College Park, MD 20742 (United States); Saito, Shinji [Graduate School of Science, Nagoya University, Furocho, Chikusa, Nagoya 464-8601 (Japan)

    2015-09-20

    This Letter puts forth a possible explanation for the formation of a solar wind strahl electron distribution function by means of local wave–particle interactions. A solar wind electron consists of a core and the hot “halo” electrons, which possess a net drift speed with respect to the core. According to the present model, pitch angle scattering of the initially isotropic drifting halo occurs when the enhanced whistler waves are excited by mildly anisotropic core electrons. The pitch angle scattering primarily affects the halo moving in the anti-sunward direction, resulting in pitch angle diffusion across the 90° gap through a nonlinear scattering process, and consequently leading to a reduction in the net drift speed of halo electrons. The remaining portion of the anti-sunward moving halo, which is not affected by pitch angle scattering, simply appears to form a field-aligned strahl in the electron velocity distribution. The present scenario of local generation of the strahl is demonstrated by the particle-in-cell simulation.

  10. Formation of Heliospheric Arcs of Slow Solar Wind

    Science.gov (United States)

    Higginson, A. K.; Antiochos, S. K.; Devore, C. R.; Wyper, P. F.; Zurbuchen, T. H.

    2017-01-01

    A major challenge in solar and heliospheric physics is understanding the origin and nature of the so-called slow solar wind. The Sun's atmosphere is divided into magnetically open regions, known as coronal holes, where the plasma streams out freely and fills the solar system, and closed regions, where the plasma is confined to coronal loops. The boundary between these regions extends outward as the heliospheric current sheet (HCS). Measurements of plasma composition strongly imply that much of the slow wind consists of plasma from the closed corona that escapes onto open field lines, presumably by field-line opening or by interchange reconnection. Both of these processes are expected to release closed-field plasma into the solar wind within and immediately adjacent to the HCS. Mysteriously, however, slow wind with closed-field plasma composition is often observed in situ far from the HCS. We use high-resolution, three-dimensional, magnetohydrodynamic simulations to calculate the dynamics of a coronal hole with a geometry that includes a narrow corridor flanked by closed field and is driven by supergranule-like flows at the coronal-hole boundary. These dynamics produce giant arcs of closed-field plasma that originate at the open-closed boundary in the corona, but extend far from the HCS and span tens of degrees in latitude and longitude at Earth. We conclude that such structures can account for the long-puzzling slow-wind observations.

  11. Validation of Model Forecasts of the Ambient Solar Wind

    Science.gov (United States)

    Macneice, P. J.; Hesse, M.; Kuznetsova, M. M.; Rastaetter, L.; Taktakishvili, A.

    2009-01-01

    Independent and automated validation is a vital step in the progression of models from the research community into operational forecasting use. In this paper we describe a program in development at the CCMC to provide just such a comprehensive validation for models of the ambient solar wind in the inner heliosphere. We have built upon previous efforts published in the community, sharpened their definitions, and completed a baseline study. We also provide first results from this program of the comparative performance of the MHD models available at the CCMC against that of the Wang-Sheeley-Arge (WSA) model. An important goal of this effort is to provide a consistent validation to all available models. Clearly exposing the relative strengths and weaknesses of the different models will enable forecasters to craft more reliable ensemble forecasting strategies. Models of the ambient solar wind are developing rapidly as a result of improvements in data supply, numerical techniques, and computing resources. It is anticipated that in the next five to ten years, the MHD based models will supplant semi-empirical potential based models such as the WSA model, as the best available forecast models. We anticipate that this validation effort will track this evolution and so assist policy makers in gauging the value of past and future investment in modeling support.

  12. Mirror Instability in the Solar Wind: The Theory Revisited

    Science.gov (United States)

    Barnes, A.

    1995-01-01

    "Magnetic holes", localized depressions in the interplanetary magnetic field, have been identified in Ulysses data over a range of several AU and as far as 23 degrees south in latitude by Winterhalter et al., who concluded that these structures are most likely the remnants of structures caused by occasional mirror-mode instability in the solar wind. However, these authors, like a number of previous investigators, used the mirror stability criterion derived from the kinetic theory under very special assumptions. On the other hand, theoretical investigations using the fully self-consistent kinetic theory (Vlasov-Maxwell equations) have shown that the mirror stability criterion is more complicated when electrons and ions have different anisotropies, as is normally the case in the solar wind. Winterhalter et al used an instability criterion of the form R is greater than 1, where R is a function of the thermal anisotropy; the correct criterion (for bi-Maxwellian distributions) is R R is greater than 1 - x(exp 2), where x is a real quantity that depends on both the proton anisotropy and electron anisotropy. So nonzero x would modify the Winterhalter et al results in the direction of reinforcing their conclusions. We have revisited the instability criterion in its most general form, allowing for (a) non-Maxwellian velocity distributions, (b) multiple ion species, and (c) interparticle streaming. These results should give sound theoretical grounding for future observational studies related to the mirror instability, by Ulysses and other spacecraft.

  13. Scaling of the electron dissipation range of solar wind turbulence

    CERN Document Server

    Sahraoui, F; De Patoul, J; Belmont, G; Goldstein, M L; Retino, A; Robert, P; Cornilleau-Wehrlin, N; Canu, P

    2013-01-01

    Electron scale solar wind turbulence has attracted great interest in recent years. Clear evidences have been given from the Cluster data that turbulence is not fully dissipated near the proton scale but continues cascading down to the electron scales. However, the scaling of the energy spectra as well as the nature of the plasma modes involved at those small scales are still not fully determined. Here we survey 10 years of the Cluster search-coil magnetometer (SCM) waveforms measured in the solar wind and perform a statistical study of the magnetic energy spectra in the frequency range [$1, 180$]Hz. We show that a large fraction of the spectra exhibit clear breakpoints near the electon gyroscale $\\rho_e$, followed by steeper power-law like spectra. We show that the scaling below the electron breakpoint cannot be determined unambiguously due to instrumental limitations that will be discussed in detail. We compare our results to recent ones reported in other studies and discuss their implication on the physical...

  14. A Model for the Sources of the Slow Solar Wind

    Science.gov (United States)

    Antiochos, Spiro K.; Mikic, Z.; Lionello, R.; Titov, V.; Linker, J.

    2010-05-01

    Models for the origin of the slow solar wind must account for two seemingly contradictory observations: The slow wind has the composition of the closed-field corona, implying that it originates at the open-closed field boundary layer, but it also has large angular width, up to 40 degrees. We propose a model that can explain both observations. The key idea is that the source of the slow wind at the Sun is a network of narrow (possibly singular) open-field corridors that map to a web of separatrices and quasi-separatrix layers in the heliosphere. We calculate with high numerical resolution, the quasi-steady solar wind and magnetic field for a Carrington rotation centered about the August 1, 2008 total solar eclipse. Our numerical results demonstrate that, at least for this time period, a web of separatrices (S-web) forms with sufficient density and extent in the heliosphere to account for the observed properties of the slow wind. We discuss the implications of our S-web model for the structure and dynamics of the corona and heliosphere, and propose further tests of the model. This work was supported, in part, by the NASA HTP, TR&T and SR&T programs.

  15. Turbulence and Global Properties of the Solar Wind

    Science.gov (United States)

    Goldstein, Melvyn L.

    2010-01-01

    The solar wind shows striking characteristics that suggest that it is a turbulent magnetofluid, but the picture is not altogether simple. From the earliest observations, a strong correlation between magnetic fluctuations and plasma velocity fluctuations was noted. The high corrections suggest that the fluctuations are Alfven waves. In addition, the power spectrum of the magnetic fluctuation showed evidence of an inertial range that resembled that seen in fully-developed fluid turbulence. Alfven waves, however, are exact solutions of the equations of incompressible magnetohydrodynamics. Thus, there was a puzzle: how can a magnetofluid consisting of Alfven waves be turbulent? The answer lay in the role of velocity shears in the solar wind that could drive turbulent evolution. Puzzles remain: for example, the power spectrum of the velocity fluctuations is less steep than the slope of the magnetic fluctuations. The plasma in the magnetic tail of Earth's magnetosphere also shows aspects of turbulence, as does the plasma in the dayside magnetosphere near the poles the dayside cusps. Recently, new analyses of high time resolution magnetic field data from Cluster have offered a glimpse of how turbulence is dissipated, thus heating the ambient plasma.

  16. The Solar Wind as a Magnetofluid Turbulence Laboratory

    Science.gov (United States)

    Goldstein, Melvyn L.

    2011-01-01

    The solar wind is the Sun's exosphere. As the solar atmosphere expands into interplanetary space, it is accelerated and heated. Data from spacecraft located throughout the heliosphere have revealed that this exosphere has velocities of several hundred kilometers/sec, densities at Earth orbit of about 5 particles/cu cm, and an entrained magnetic field that at Earth orbit that is about 5 10-5 Gauss. A fascinating feature of the solar wind is that the magnetic field fluctuates in a way that is highly reminiscent of "Alfven waves, i.e., the fluctuating magnetic fields are more-or-less aligned with fluctuations in the velocity of the plasma and, with proper normalization, have approximately equal magnitudes. The imperfect (observed) alignment leads to a variety of complex interactions. In many respects, the flow patterns appear to be an example of fully developed magneto fluid turbulence. Recently, the dissipation range of this turbulence has been studied using search coil magnetometer data from the STAFF instrument on the four Cluster spacecraft. I will attempt to give an overview of selected properties of this large-scale and small-scale turbulence.

  17. Modeling of short scale turbulence in the solar wind

    Directory of Open Access Journals (Sweden)

    V. Krishan

    2005-01-01

    Full Text Available The solar wind serves as a laboratory for investigating magnetohydrodynamic turbulence under conditions irreproducible on the terra firma. Here we show that the frame work of Hall magnetohydrodynamics (HMHD, which can support three quadratic invariants and allows nonlinear states to depart fundamentally from the Alfvénic, is capable of reproducing in the inertial range the three branches of the observed solar wind magnetic fluctuation spectrum - the Kolmogorov branch f -5/3 steepening to f -α1 with on the high frequency side and flattening to f -1 on the low frequency side. These fluctuations are found to be associated with the nonlinear Hall-MHD Shear Alfvén waves. The spectrum of the concomitant whistler type fluctuations is very different from the observed one. Perhaps the relatively stronger damping of the whistler fluctuations may cause their unobservability. The issue of equipartition of energy through the so called Alfvén ratio acquires a new status through its dependence, now, on the spatial scale.

  18. The Contribution of Coronal Jets To The Solar Wind

    CERN Document Server

    Lionello, R; Titov, V S; Leake, J E; MikiĆ, Z; Linker, J A; Linton, M G

    2016-01-01

    Transient collimated plasma eruptions in the solar corona, commonly known as coronal (or X-ray) jets, are among the most interesting manifestations of solar activity. It has been suggested that these events contribute to the mass and energy content of the corona and solar wind, but the extent of these contributions remains uncertain. We have recently modeled the formation and evolution of coronal jets using a three-dimensional (3D) magnetohydrodynamic (MHD) code with thermodynamics in a large spherical domain that includes the solar wind. Our model is coupled to 3D MHD flux-emergence simulations, i.e, we use boundary conditions provided by such simulations to drive a time-dependent coronal evolution. The model includes parametric coronal heating, radiative losses, and thermal conduction, which enables us to simulate the dynamics and plasma properties of coronal jets in a more realistic manner than done so far. Here we employ these simulations to calculate the amount of mass and energy transported by coronal j...

  19. Multifractal analysis of high resolution solar wind proton density measurements

    Science.gov (United States)

    Sorriso-Valvo, Luca; Carbone, Francesco; Leonardis, Ersilia; Chen, Christopher H. K.; Šafránková, Jana; Němeček, Zdenek

    2017-03-01

    The solar wind is a highly turbulent medium, with a high level of field fluctuations throughout a broad range of scales. These include an inertial range where a turbulent cascade is assumed to be active. The solar wind cascade shows intermittency, which however may depend on the wind conditions. Recent observations have shown that ion-scale magnetic turbulence is almost self-similar, rather than intermittent. A similar result was observed for the high resolution measurements of proton density provided by the spacecraft Spektr-R. Intermittency may be interpreted as the result of the multifractal properties of the turbulent cascade. In this perspective, this paper is devoted to the description of the multifractal properties of the high resolution density measurements. In particular, we have used the standard coarse-graining technique to evaluate the generalized dimensions Dq , and from these the multifractal spectrum f (α) , in two ranges of scale. A fit with the p-model for intermittency provided a quantitative measure of multifractality. Such indicator was then compared with alternative measures: the width of the multifractal spectrum, the peak of the kurtosis, and its scaling exponent. The results indicate that the small-scale fluctuations are multifractal, and suggest that different measures of intermittency are required to fully understand the small scale cascade.

  20. Solar wind control of the local time of substorm onset

    Science.gov (United States)

    Grocott, Adrian; Case, Nathan; Laundal, Karl; Laurens, Hannah; Milan, Steve

    2017-04-01

    We use solar wind and interplanetary magnetic field data, along with satellite global auroral imagery, to investigate what controls the magnetic local time (MLT) of substorm onset. We find that substorm onsets occur over a wide range of MLTs (18 - 4 hrs), with a typical MLT (mode) of 23 hrs. In agreement with previous studies, IMF BY , acts to move the onset to an earlier/later local time in the northern hemisphere and a later/earlier local time in the southern hemisphere, depending on the sign of BY , consistent with a twist of the conjugate magnetic field line. This effect explains a small fraction of the observed MLT variation (˜ 1 hr), but cannot account for the tendency of onset to be often displaced to earlier ( 23 hrs) MLTs in both hemispheres. We also inspect the relationship between solar wind V Y and onset MLT, which also has a small, but measurable effect on the local time of substorm onset. This effect acts in the same sense in the northern and southern hemispheres, moving onset to earlier times for positive V Y and later times for negative V Y . We find that a function relating both BY and V Y to onset MLT produces a better fit than a function based on either parameter alone.

  1. Observations of Anisotropic Scaling of Solar Wind Turbulence

    Science.gov (United States)

    Luo, Q. Y.; Wu, D. J.

    2010-05-01

    Using high-speed solar wind data recorded by the Ulysses spacecraft, we investigate and estimate the anisotropic inertial range scaling of the interplanetary magnetic field. We apply the method of the magnetic structure function (MSF), Sn (τ) = lang|b(t + τ) - b(t)| n rang vprop τζ(n), to analyze the scaling of solar wind turbulence over the range from 1 s to 104 s. By sorting the fluctuations according to the direction of the local mean magnetic field, we obtain a second-order structure function in (r, Θ) coordinates that reveals the scale-dependent anisotropy of the power spectrum. The scale-dependent anisotropy of the MSF indicates that the fluctuation energy tends to cascade toward the direction perpendicular to the local field. The dependence of the MSF scaling index ζ on the direction of the local field is found to be similar to that reported in Horbury et al. and Podesta, with ζbottom = 0.53 ± 0.18 and ζpar = 1.00 ± 0.14. Furthermore, we estimate and find the scaling law between the perpendicular and parallel scales r par vprop r 0.614 bottom, which implies the elongation along the parallel direction as the turbulence eddy evolves toward the small lengthscales. These results are in agreement with the predictions of magnetohydrodynamic turbulence theory.

  2. Solar wind implication on dust ion acoustic rogue waves

    Science.gov (United States)

    Abdelghany, A. M.; Abd El-Razek, H. N.; Moslem, W. M.; El-Labany, S. K.

    2016-06-01

    The relevance of the solar wind with the magnetosphere of Jupiter that contains positively charged dust grains is investigated. The perturbation/excitation caused by streaming ions and electron beams from the solar wind could form different nonlinear structures such as rogue waves, depending on the dominant role of the plasma parameters. Using the reductive perturbation method, the basic set of fluid equations is reduced to modified Korteweg-de Vries (KdV) and further modified (KdV) equation. Assuming that the frequency of the carrier wave is much smaller than the ion plasma frequency, these equations are transformed into nonlinear Schrödinger equations with appropriate coefficients. Rational solution of the nonlinear Schrödinger equation shows that rogue wave envelopes are supported by the present plasma model. It is found that the existence region of rogue waves depends on the dust-acoustic speed and the streaming temperatures for both the ions and electrons. The dependence of the maximum rogue wave envelope amplitude on the system parameters has been investigated.

  3. The Solar Wind Charge-Exchange Production Factor for Hydrogen

    CERN Document Server

    Kuntz, K D; Collier, M R; Connor, H K; Cravens, T E; Koutroumpa, D; Porter, F S; Robertson, I P; Sibeck, D G; Snowden, S L; Thomas, N E; Wash, B M

    2015-01-01

    The production factor, or broad band averaged cross-section, for solar wind charge-exchange with hydrogen producing emission in the ROSAT 1/4 keV (R12) band is $3.8\\pm0.2\\times10^{-20}$ count degree$^{-2}$ cm$^4$. This value is derived from a comparison of the Long-Term (background) Enhancements in the ROSAT All-Sky Survey with magnetohysdrodynamic simulations of the magnetosheath. This value is 1.8 to 4.5 times higher than values derived from limited atomic data, suggesting that those values may be missing a large number of faint lines. This production factor is important for deriving the exact amount of 1/4 keV band flux that is due to the Local Hot Bubble, for planning future observations in the 1/4 keV band, and for evaluating proposals for remote sensing of the magnetosheath. The same method cannot be applied to the 3/4 keV band as that band, being composed primarily of the oxygen lines, is far more sensitive to the detailed abundances and ionization balance in the solar wind. We also show, incidentally,...

  4. Magnetic Influences on the Solar Wind (Ph.D. Dissertation)

    CERN Document Server

    Woolsey, Lauren N

    2016-01-01

    The steady, supersonic outflow from the Sun we call the solar wind was first posited in the 1950s and initial theories rightly linked the acceleration of the wind to the existence of the million-degree solar corona. Still today, the wind acceleration mechanisms and the coronal heating processes remain unsolved challenges in solar physics. In this work, I seek to answer a portion of the mystery by focusing on a particular acceleration process: Alfven waves launched by the motion of magnetic field footpoints in the photosphere. The entire corona is threaded with magnetic loops and flux tubes that open up into the heliosphere. I have sought a better understanding of the role these magnetic fields play in determining solar wind properties in open flux tubes. After an introduction of relevant material, I discuss my parameter study of magnetic field profiles and the statistical understanding we can draw from the resulting steady-state wind. In the chapter following, I describe how I extended this work to consider t...

  5. Extended MHD Turbulence and Its Applications to the Solar Wind

    Science.gov (United States)

    Abdelhamid, Hamdi M.; Lingam, Manasvi; Mahajan, Swadesh M.

    2016-10-01

    Extended MHD is a one-fluid model that incorporates two-fluid effects such as electron inertia and the Hall drift. This model is used to construct fully nonlinear Alfvénic wave solutions, and thereby derive the kinetic and magnetic spectra by resorting to a Kolmogorov-like hypothesis based on the constant cascading rates of the energy and generalized helicities of this model. The magnetic and kinetic spectra are derived in the ideal (k\\lt 1/{λ }i), Hall (1/{λ }i\\lt k\\lt 1/{λ }e), and electron inertia (k\\gt 1/{λ }e) regimes; k is the wavenumber and {λ }s=c/{ω }{ps} is the skin depth of species “s.” In the Hall regime, it is shown that the emergent results are fully consistent with previous numerical and analytical studies, especially in the context of the solar wind. The focus is primarily on the electron inertia regime, where magnetic energy spectra with power-law indexes of -11/3 and -13/3 are always recovered. The latter, in particular, is quite close to recent observational evidence from the solar wind with a potential slope of approximately -4 in this regime. It is thus plausible that these spectra may constitute a part of the (extended) inertial range, as opposed to the standard “dissipation” range paradigm.

  6. Extended MHD turbulence and its applications to the solar wind

    CERN Document Server

    Abdelhamid, Hamdi M; Mahajan, Swadesh M

    2016-01-01

    Extended MHD is a one-fluid model that incorporates two-fluid effects such as electron inertia and the Hall drift. This model is used to construct fully nonlinear Alfv\\'enic wave solutions, and thereby derive the kinetic and magnetic spectra by resorting to a Kolmogorov-like hypothesis based on the constant cascading rates of the energy and generalized helicities of this model. The magnetic and kinetic spectra are derived in the ideal $\\left(k 1/\\lambda_e\\right)$ regimes; $k$ is the wavenumber and $\\lambda_s = c/\\omega_{p s}$ is the skin depth of species `$s$'. In the Hall regime, it is shown that the emergent results are fully consistent with previous numerical and analytical studies, especially in the context of the solar wind. The focus is primarily on the electron inertia regime, where magnetic energy spectra with power-law indexes of $-11/3$ and $-13/3$ are always recovered. The latter, in particular, is quite close to recent observational evidence from the solar wind with a potential slope of approxima...

  7. Critical point of the solar wind by radio sounding data

    Science.gov (United States)

    Lotova, N. A.; Oraevsky, V. N.; Pisarenko, Ya. V.; Vladimirskii, K. V.

    1995-01-01

    Results of the close-to-Sun plasmas sounding at the transonic region of the solar wind, where the sub-to supersonic flow transition proceeds (at 10 to 40 solar radii from the Sun), are presented. Natural sources of two types were used, water vapour maser sources at 1.35 cm and guasars at 2.9 m wavelength. scattering observations cover the period of 1986 to 1993, Russian Academy of Sciences telescopes RT-22 and DCR-1000 were used, IPS index and scattering angle being the immediate results of observations. Extensive studies of the scintillation index and scattering angle radial profiles reveal a remarkable structural detail, 'transonic region forrunner'-narrow region of diminished scattering close to the internal border of the extended transonic region with its characteristic enhanced scattering. Comparisons of the scattering and plasma velocity profiles let it possible to determine the critical point positions by the comparatively simple scattering observations. This new possibility widely improves the process of the basic data accumulation in the fundamental problem of the solar wind acceleration mechanism.

  8. Orbit limited theory in the solar wind - κ distributions

    Directory of Open Access Journals (Sweden)

    Martinović M.M.

    2016-01-01

    Full Text Available When a solid object is immersed into ionized gas it gets brought to a certain value of electrostatic potential and surrounded by a space charge region called ‘plasma sheath’. Through this region, particles are attracted or repelled from the surface of the charge collecting object. For collisionless plasma, this process is described by the so-called orbit limited theory, which explains how the collection of particles is determined by the collector geometry and plasma velocity distribution function (VDF. In this article, we provide explicit expressions for orbit-limited currents for generalized Lorentzian (κ distributions. This work is useful to describe the charging processes of objects in non-collisional plasmas like the solar wind, where the electrons VDF is often observed to exhibit quasi power-law populations of suprathermal particles. It is found that these ‘suprathermals’ considerably increase the charge collection. Since the surface charging process that determines the value of electrostatic potential is also affected by the plasma VDF, calculation of the collector potential in the solar wind is described along with some quantitative predictions. [Projekat Ministarstva nauke Republike Srbije, br. 176002

  9. Model for vortex turbulence with discontinuities in the solar wind

    Directory of Open Access Journals (Sweden)

    O. P. Verkhoglyadova

    2003-01-01

    Full Text Available A model of vortex with embedded discontinuities in plasma flow is developed in the framework of ideal MHD in a low b plasma. Vortex structures are considered as a result of 2-D evolution of nonlinear shear Alfvén waves in the heliosphere. Physical properties of the solutions and vector fields are analyzed and the observational aspects of the model are discussed. The ratio of normal components to the discontinuity Br /Vr can be close to -2. The alignment between velocity and magnetic field vectors takes place. Spacecraft crossing such vortices will typically observe a pair of discontinuities, but with dissimilar properties. Occurrence rate for different discontinuity types is estimated and agrees with observations in high-speed solar wind stream. Discontinuity crossing provides a backward rotation of magnetic field vector and can be observed as part of a backward arc. The Ulysses magnetometer data obtained in the fast solar wind are compared with the results of theoretical modelling.

  10. Predicted impacts of proton temperature anisotropy on solar wind turbulence

    Energy Technology Data Exchange (ETDEWEB)

    Klein, K. G., E-mail: kristopher.klein@unh.edu [Space Science Center, University of New Hampshire, Durham, New Hampshire 03824 (United States); Howes, G. G. [Department of Physics and Astronomy, University of Iowa, Iowa City, Iowa 52242 (United States)

    2015-03-15

    Particle velocity distributions measured in the weakly collisional solar wind are frequently found to be non-Maxwellian, but how these non-Maxwellian distributions impact the physics of plasma turbulence in the solar wind remains unanswered. Using numerical solutions of the linear dispersion relation for a collisionless plasma with a bi-Maxwellian proton velocity distribution, we present a unified framework for the four proton temperature anisotropy instabilities, identifying the associated stable eigenmodes, highlighting the unstable region of wavevector space and presenting the properties of the growing eigenfunctions. Based on physical intuition gained from this framework, we address how the proton temperature anisotropy impacts the nonlinear dynamics of the Alfvénic fluctuations underlying the dominant cascade of energy from large to small scales and how the fluctuations driven by proton temperature anisotropy instabilities interact nonlinearly with each other and with the fluctuations of the large-scale cascade. We find that the nonlinear dynamics of the large-scale cascade is insensitive to the proton temperature anisotropy and that the instability-driven fluctuations are unlikely to cause significant nonlinear evolution of either the instability-driven fluctuations or the turbulent fluctuations of the large-scale cascade.

  11. Predicted impacts of proton temperature anisotropy on solar wind turbulence

    Science.gov (United States)

    Klein, K. G.; Howes, G. G.

    2015-03-01

    Particle velocity distributions measured in the weakly collisional solar wind are frequently found to be non-Maxwellian, but how these non-Maxwellian distributions impact the physics of plasma turbulence in the solar wind remains unanswered. Using numerical solutions of the linear dispersion relation for a collisionless plasma with a bi-Maxwellian proton velocity distribution, we present a unified framework for the four proton temperature anisotropy instabilities, identifying the associated stable eigenmodes, highlighting the unstable region of wavevector space and presenting the properties of the growing eigenfunctions. Based on physical intuition gained from this framework, we address how the proton temperature anisotropy impacts the nonlinear dynamics of the Alfvénic fluctuations underlying the dominant cascade of energy from large to small scales and how the fluctuations driven by proton temperature anisotropy instabilities interact nonlinearly with each other and with the fluctuations of the large-scale cascade. We find that the nonlinear dynamics of the large-scale cascade is insensitive to the proton temperature anisotropy and that the instability-driven fluctuations are unlikely to cause significant nonlinear evolution of either the instability-driven fluctuations or the turbulent fluctuations of the large-scale cascade.

  12. Implications of solar wind measurements for solar models and composition

    CERN Document Server

    Serenelli, Aldo; Villante, Francesco L; Vincent, Aaron C; Asplund, Martin; Basu, Sarbani; Grevesse, Nicolas; Pena-Garay, Carlos

    2016-01-01

    We critically examine recent claims of a high solar metallicity by von Steiger \\& Zurbuchen (2016; vSZ16) based on in situ measurements of the solar wind, rather than the standard spectroscopically-inferred abundances (Asplund et al. 2009). We test the claim by Vagnozzi et al. (2016) that a composition based on the solar wind enables one to construct a standard solar model in agreement with helioseismological observations and thus solve the decades-old solar modelling problem. We show that, although some helioseismological observables are improved compared to models computed with established abundances, most are in fact worse. The high abundance of refractory elements leads to an overproduction of neutrinos, with a predicted $^8$B flux that is nearly twice its observed value, and $^7$Be and CNO fluxes that are experimentally ruled out at high confidence. A combined likelihood analysis shows that models using the vSZ16 abundances fare much worse than AGSS09 despite a higher metallicity. We also present ast...

  13. Small solar wind transients: Stereo-A observations in 2009

    Energy Technology Data Exchange (ETDEWEB)

    Yu, W.; Farrugia, C. J.; Galvin, A. B.; Simunac, K. D. C.; Popecki, M. A.; Lugaz, N. [Space Science Center, University of New Hampshire, Durham, NH 03824 (United States); Kilpua, E. K. J. [Dept. of Physics, Division of Geophysics and Astronomy, University of Helsinki (Finland); Moestl, C. [Institute of Physics, University of Graz, 8010 Graz, Austria and Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States); Luhmann, J. G. [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States); Opitz, A.; Sauvaud, J.-A. [Institut de Recherche en Astrophysique et Planetologie (CNRS-UPS), Universite de Toulouse, F-31038, Toulouse (France)

    2013-06-13

    Year 2009 was the last year of a long and pronounced solar activity minimum. In this year the solar wind in the inner heliosphere was for 90% of the time slow (< 450 km s{sup -1}) and with a weaker magnetic field strength compared to the previous solar minimum 1995-1996. We choose this year to present the results of a systematic search for small solar wind transients (STs) observed by the STEREO-Ahead (ST-A) probe. The data are from the PLASTIC and IMPACT instrument suites. By 'small' we mean a duration from {approx}1 to 12 hours. The parameters we search for to identify STs are (i) the total field strength, (ii) the rotation of the magnetic field vector, (iii) its smoothness, (iv) proton temperature, (v) proton beta, and (vi) Alfven Mach number. We find 45 examples. The STs have an average duration of {approx}4 hours. Ensemble averages of key quantities are: (i) maximum B = 7.01 nT; (ii) proton {beta}= 0.18; (iii) proton thermal speed = 20.8 km s{sup -1}; and (iv) Alfven Mach number = 6.13. No distinctive feature is found in the pitch angle distributions of suprathermal electrons. Our statistical results are compared with those of STs observed near Earth by Wind during 2009.

  14. Implications of solar wind measurements for solar models and composition

    Science.gov (United States)

    Serenelli, Aldo; Scott, Pat; Villante, Francesco L.; Vincent, Aaron C.; Asplund, Martin; Basu, Sarbani; Grevesse, Nicolas; Peña-Garay, Carlos

    2016-11-01

    We critically examine recent claims of a high solar metallicity by von Steiger & Zurbuchen (2016, vSZ16) based on in situ measurements of the solar wind, rather than the standard spectroscopically inferred abundances (Asplund et al. 2009, hereafter AGSS09). We test the claim by Vagnozzi et al. (2016) that a composition based on the solar wind enables one to construct a standard solar model in agreement with helioseismological observations and thus solve the decades-old solar modelling problem. We show that, although some helioseismological observables are improved compared to models computed with spectroscopic abundances, most are in fact worse. The high abundance of refractory elements leads to an overproduction of neutrinos, with a predicted 8B flux that is nearly twice its observed value, and 7Be and CNO fluxes that are experimentally ruled out at high confidence. A combined likelihood analysis shows that models using the vSZ16 abundances are worse than AGSS09 despite a higher metallicity. We also present astrophysical and spectroscopic arguments showing the vSZ16 composition to be an implausible representation of the solar interior, identifying the first ionization potential effect in the outer solar atmosphere and wind as the likely culprit.

  15. Programmatically Optimized SEM Image Acquisition for Measurement of Contamination on Molybdenum Coated Foils from the NASA Genesis Mission

    Science.gov (United States)

    Gil, A.

    2016-12-01

    The NASA Genesis Mission flew high-purity collector materials on a satellite from 2001-2004 to collect a sample of the solar wind. Upon return to Earth, a spacecraft malfunction caused the onboard sample materials to be severely contaminated during the crash landing in the Utah desert. As part of an ongoing effort to decontaminate the collector materials, they are being scanned with a scanning electron microscope (SEM) to determine the amount of dirt and spacecraft debris contaminating the collectors. This effort is underway currently, but we have identified an opportunity to improve the quality of the SEM data collected. At present, many small images are acquired and stitched together to form larger images of Genesis collector pieces, which are then analyzed. The collectors are physically distorted, however, and the imaging method presently used doesn't allow imaging parameters to be adjusted between images to correct for this distortion. In order to improve the quality of the collected imaging, we are developing a program to acquire a focus map of each sample prior to image collection. The program then uses this data to adjust the position of the sample in the SEM to image all sections in focus and at a constant focal length. This is accomplished using the Python programming language, and the programmatic interface built into our Tescan VEGA Scanning Electron Microscope. Our approach, progress to date, and challenges are discussed.

  16. Solar identification of solar-wind disturbances observed at Ulysses

    Science.gov (United States)

    Lemen, J. R.; Acton, L. W.; Alexander, D.; Galvin, A. B.; Harvey, K. L.; Hoeksema, J. T.; Zhao, X.; Hudson, H. S.

    1996-07-01

    The Ulysses polar passages are producing a unique set of observations of solar-wind disturbances at high heliographic latitudes. In this paper we use the Yohkoh soft X-ray telescope (SXT) to locate some of these events, as defined by the Ulysses/SWICS data, in the solar corona. Of 8 events, we identify two with flares, three with front-side large arcade events, two with far-side events, and one was not seen in the Ulysses data. The arcade events generally resemble long-duration flares seen in active regions, but are larger, slower, and cooler. We present Yohkoh images of each of these events. In the large arcade events (see Alexander et al., 1996, for a detailed look at one of them) the magnetic morphology at the location of the Yohkoh arcade is generally consistent with the development of a large system of loops. Some of the identifications are ambiguous, and we summarize the reasons for this. From the SWICS data we have obtained ionization temperatures for several events, and find that they have no obvious pattern in relation to the X-ray temperatures; this may be expected on the basis that the interplanetary plasma cloud is physically distinct from the plasma trapped in the corona. Soft X-ray observations of the solar corona show occasional occurrences of large-scale brightenings in the form of arcades of loops. Such structures have been known since Skylab (e.g., Sturrock, 1980), and have a clear relationship with coronal mass ejections (e.g., Kahler, 1977). We now may study this phenomenon statistically with the much more comprehensive Yohkoh observations; with Yohkoh movies we can also begin to extend our knowledge to the three-dimensional development of the structures. At the same time Ulysses has sampled the latitude dependence of the interplanetary effects. With this paper we introduce this subject and provide a preliminary listing of events from the passage of Ulysses through high heliographic latitudes. The starting point of the present survey is a list

  17. Cometary X-rays : solar wind charge exchange in cometary atmospheres

    NARCIS (Netherlands)

    Bodewits, Dennis

    2007-01-01

    The interaction of the solar wind with the planets and the interstellar medium is of key importance for the evolution of our solar system. The interaction with Earth's atmosphere is best known for the northern light. In case of Mars, the interaction with the solar wind might have lead to the erosion

  18. Three-Dimensional Magnetohydrodynamic Modeling of the Solar Wind Including Pickup Protons and Turbulence Transport

    Science.gov (United States)

    Usmanov, Arcadi V.; Goldstein, Melvyn L.; Matthaeus, William H.

    2012-01-01

    To study the effects of interstellar pickup protons and turbulence on the structure and dynamics of the solar wind, we have developed a fully three-dimensional magnetohydrodynamic solar wind model that treats interstellar pickup protons as a separate fluid and incorporates the transport of turbulence and turbulent heating. The governing system of equations combines the mean-field equations for the solar wind plasma, magnetic field, and pickup protons and the turbulence transport equations for the turbulent energy, normalized cross-helicity, and correlation length. The model equations account for photoionization of interstellar hydrogen atoms and their charge exchange with solar wind protons, energy transfer from pickup protons to solar wind protons, and plasma heating by turbulent dissipation. Separate mass and energy equations are used for the solar wind and pickup protons, though a single momentum equation is employed under the assumption that the pickup protons are comoving with the solar wind protons.We compute the global structure of the solar wind plasma, magnetic field, and turbulence in the region from 0.3 to 100 AU for a source magnetic dipole on the Sun tilted by 0 deg - .90 deg and compare our results with Voyager 2 observations. The results computed with and without pickup protons are superposed to evaluate quantitatively the deceleration and heating effects of pickup protons, the overall compression of the magnetic field in the outer heliosphere caused by deceleration, and the weakening of corotating interaction regions by the thermal pressure of pickup protons.

  19. Solar Wind Driving of Magnetospheric ULF Waves: Pulsations Driven by Velocity Shear at the Magnetopause

    CERN Document Server

    Claudepierre, S G; Wiltberger, M; 10.1029/2007JA012890

    2010-01-01

    We present results from global, three-dimensional magnetohydrodynamic (MHD) simulations of the solar wind/magnetosphere interaction. These MHD simulations are used to study ultra low frequency (ULF) pulsations in the Earth's magnetosphere driven by shear instabilities at the flanks of the magnetopause. We drive the simulations with idealized, constant solar wind input parameters, ensuring that any discrete ULF pulsations generated in the simulation magnetosphere are not due to fluctuations in the solar wind. The simulations presented in this study are driven by purely southward interplanetary magnetic field (IMF) conditions, changing only the solar wind driving velocity while holding all of the other solar wind input parameters constant. We find surface waves near the dawn and dusk flank magnetopause and show that these waves are generated by the Kelvin-Helmholtz (KH) instability. We also find that two KH modes are generated near the magnetopause boundary. One mode, the magnetopause KH mode, propagates tailwa...

  20. Three-dimensional exploration of the solar wind using observations of interplanetary scintillation.

    Science.gov (United States)

    Tokumaru, Munetoshi

    2013-01-01

    The solar wind, a supersonic plasma flow continuously emanating from the Sun, governs the space environment in a vast region extending to the boundary of the heliosphere (∼100 AU). Precise understanding of the solar wind is of importance not only because it will satisfy scientific interest in an enigmatic astrophysical phenomenon, but because it has broad impacts on relevant fields. Interplanetary scintillation (IPS) of compact radio sources at meter to centimeter wavelengths serves as a useful ground-based method for investigating the solar wind. IPS measurements of the solar wind at a frequency of 327 MHz have been carried out regularly since the 1980s using the multi-station system of the Solar-Terrestrial Environment Laboratory (STEL) of Nagoya University. This paper reviews new aspects of the solar wind revealed from our IPS observations.

  1. What is the best method to calculate the solar wind propagation delay?

    Energy Technology Data Exchange (ETDEWEB)

    Mailyan, B. [Yerevan State Univ. (Armenia); Munteanu, C. [Alexandru Ioan Cuza Univ., Iasi (Romania); Haaland, S. [Bergen Univ. (Norway); Max-Planck-Inst. for Solar Systems (Germany)

    2008-07-01

    We present a statistical study of propagation times of solar wind discontinuities between Advanced Composition Explorer (ACE) spacecraft orbiting the L1 libration point and the Cluster quartet of spacecraft near the Earth's magnetopause. The propagation times for almost 200 events are compared with the predicted times from four different models. The simplest model assumes a constant convective motion of solar wind disturbances along the Sun-Earth line, whereas more sophisticated models take the orientation of the discontinuity as well as the real positions of the solar wind monitor and target into account. The results show that taking orientation and real position of the solar wind monitor and target into account gives a more precise time delay estimation in most cases. In particular, we show that recent modifications to the minimum variance technique can improve the estimation of propagation times of solar wind discontinuities. (orig.)

  2. Reconstructing the Solar Wind From Its Early History To Current Epoch

    CERN Document Server

    Airapetian, Vladimir S

    2016-01-01

    Stellar winds from active solar type stars can play a crucial role in removal of stellar angular momentum and erosion of planetary atmospheres. However, major wind properties except for mass loss rates cannot be directly derived from observations. We employed a three dimensional magnetohydrodynamic Alfven wave driven solar wind model, ALF3D, to reconstruct the solar wind parameters including the mass loss rate, terminal velocity and wind temperature at 0.7, 2 and 4.65 Gyr. Our model treats the wind thermal electrons, protons and pickup protons as separate fluids and incorporates turbulence transport, eddy viscosity, turbulent resistivity, and turbulent heating to properly describe proton and electron temperatures of the solar wind. To study the evolution of the solar wind, we specified three input model parameters, the plasma density, Alfven wave amplitude and the strength of the dipole magnetic field at the wind base for each of three solar wind evolution models that are consistent with observational constra...

  3. What is the best method to calculate the solar wind propagation delay?

    Directory of Open Access Journals (Sweden)

    B. Mailyan

    2008-08-01

    Full Text Available We present a statistical study of propagation times of solar wind discontinuities between Advanced Composition Explorer (ACE spacecraft orbiting the L1 libration point and the Cluster quartet of spacecraft near the Earth's magnetopause. The propagation times for almost 200 events are compared with the predicted times from four different models. The simplest model assumes a constant convective motion of solar wind disturbances along the Sun-Earth line, whereas more sophisticated models take the orientation of the discontinuity as well as the real positions of the solar wind monitor and target into account. The results show that taking orientation and real position of the solar wind monitor and target into account gives a more precise time delay estimation in most cases. In particular, we show that recent modifications to the minimum variance technique can improve the estimation of propagation times of solar wind discontinuities.

  4. A new view on the solar wind interaction with the Moon

    CERN Document Server

    Bhardwaj, Anil; Alok, Abhinaw; Barabash, Stas; Wieser, Martin; Futaana, Yoshifumi; Wurz, Peter; Vorburger, Audrey; Holmström, Mats; Lue, Charles; Harada, Yuki; Asamura, Kazushi

    2015-01-01

    Characterised by a surface bound exosphere and localised crustal magnetic fields, the Moon was considered as a passive object when solar wind interacts with it. However, the neutral particle and plasma measurements around the Moon by recent dedicated lunar missions, such as Chandrayaan-1, Kaguya, Chang'E-1, LRO, and ARTEMIS, as well as IBEX have revealed a variety of phenomena around the Moon which results from the interaction with solar wind, such as backscattering of solar wind protons as energetic neutral atoms (ENA) from lunar surface, sputtering of atoms from the lunar surface, formation of a "mini-magnetosphere" around lunar magnetic anomaly regions, as well as several plasma populations around the Moon, including solar wind protons scattered from the lunar surface, from the magnetic anomalies, pick-up ions, protons in lunar wake and more. This paper provides a review of these recent findings and presents the interaction of solar wind with the Moon in a new perspective.

  5. A new view on the solar wind interaction with the Moon

    Science.gov (United States)

    Bhardwaj, Anil; Dhanya, M. B.; Alok, Abhinaw; Barabash, Stas; Wieser, Martin; Futaana, Yoshifumi; Wurz, Peter; Vorburger, Audrey; Holmström, Mats; Lue, Charles; Harada, Yuki; Asamura, Kazushi

    2015-12-01

    Characterised by a surface bound exosphere and localised crustal magnetic fields, the Moon was considered as a passive object when solar wind interacts with it. However, the neutral particle and plasma measurements around the Moon by recent dedicated lunar missions, such as Chandrayaan-1, Kaguya, Chang'E-1, LRO, and ARTEMIS, as well as IBEX have revealed a variety of phenomena around the Moon which results from the interaction with solar wind, such as backscattering of solar wind protons as energetic neutral atoms (ENA) from lunar surface, sputtering of atoms from the lunar surface, formation of a "mini-magnetosphere" around lunar magnetic anomaly regions, as well as several plasma populations around the Moon, including solar wind protons scattered from the lunar surface, from the magnetic anomalies, pick-up ions, protons in lunar wake and more. This paper provides a review of these recent findings and presents the interaction of solar wind with the Moon in a new perspective.

  6. The distinct character of anisotropy and intermittency in inertial and kinetic range solar wind plasma turbulence

    Science.gov (United States)

    Kiyani, Khurom; Chapman, Sandra; Osman, Kareem; Sahraoui, Fouad; Hnat, Bogdan

    2014-05-01

    The anisotropic nature of the scaling properties of solar wind magnetic turbulence fluctuations is investigated scale by scale using high cadence in situ magnetic field measurements from the Cluster, ACE and STEREO spacecraft missions in both fast and slow quiet solar wind conditions. The data span five decades in scales from the inertial range to the electron Larmor radius. We find a clear transition in scaling behaviour between the inertial and kinetic range of scales, which provides a direct, quantitative constraint on the physical processes that mediate the cascade of energy through these scales. In the inertial (magnetohydrodynamic) range the statistical nature of turbulent fluctuations are known to be anisotropic, both in the vector components of the magnetic field fluctuations (variance anisotropy) and in the spatial scales of these fluctuations (wavevector or k-anisotropy). We show for the first time that, when measuring parallel to the local magnetic field direction, the full statistical signature of the magnetic and Elsasser field fluctuations is that of a non-Gaussian globally scale-invariant process. This is distinct from the classic multi-exponent statistics observed when the local magnetic field is perpendicular to the flow direction. These observations suggest the weakness, or absence, of a parallel magnetofluid turbulence energy cascade. In contrast to the inertial range, there is a successive increase toward isotropy between parallel and transverse power at scales below the ion Larmor radius, with isotropy being achieved at the electron Larmor radius. Computing higher-order statistics, we show that the full statistical signature of both parallel, and perpendicular fluctuations at scales below the ion Larmor radius are that of an isotropic globally scale-invariant non-Gaussian process. Lastly, we perform a survey of multiple intervals of quiet solar wind sampled under different plasma conditions (fast, slow wind; plasma beta etc.) and find that the

  7. Flux-tube geometry and solar wind speed during an activity cycle

    Science.gov (United States)

    Pinto, R. F.; Brun, A. S.; Rouillard, A. P.

    2016-07-01

    Context. The solar wind speed at 1 AU shows cyclic variations in latitude and in time which reflect the evolution of the global background magnetic field during the activity cycle. It is commonly accepted that the terminal (asymptotic) wind speed in a given magnetic flux-tube is generally anti-correlated with its total expansion ratio, which motivated the definition of widely used semi-empirical scaling laws relating one to the other. In practice, such scaling laws require ad hoc corrections (especially for the slow wind in the vicinities of streamer/coronal hole boundaries) and empirical fits to in situ spacecraft data. A predictive law based solely on physical principles is still missing. Aims: We test whether the flux-tube expansion is the controlling factor of the wind speed at all phases of the cycle and at all latitudes (close to and far from streamer boundaries) using a very large sample of wind-carrying open magnetic flux-tubes. We furthermore search for additional physical parameters based on the geometry of the coronal magnetic field which have an influence on the terminal wind flow speed. Methods: We use numerical magneto-hydrodynamical simulations of the corona and wind coupled to a dynamo model to determine the properties of the coronal magnetic field and of the wind velocity (as a function of time and latitude) during a whole 11-yr activity cycle. These simulations provide a large statistical ensemble of open flux-tubes which we analyse conjointly in order to identify relations of dependence between the wind speed and geometrical parameters of the flux-tubes which are valid globally (for all latitudes and moments of the cycle). Results: Our study confirms that the terminal (asymptotic) speed of the solar wind depends very strongly on the geometry of the open magnetic flux-tubes through which it flows. The total flux-tube expansion is more clearly anti-correlated with the wind speed for fast rather than for slow wind flows, and effectively controls the

  8. Compressive fluctuations in the solar wind and their polytropic index

    Directory of Open Access Journals (Sweden)

    B. Bavassano

    Full Text Available Magnetohydrodynamic compressive fluctuations of the interplanetary plasma in the region from 0.3 to 1 AU have been characterized in terms of their polytropic index. Following Chandrasekhar's approach to polytropic fluids, this index has been determined through a fit of the observed variations of density and temperature. At least three different classes of fluctuations have been identified: (1 variations at constant thermal pressure, in low-speed solar wind and without a significant dependence on distance, (2 adiabatic variations, mainly close to 1 AU and without a relevant dependence on wind speed, and (3 variations at nearly constant density, in fast wind close to 0.3 AU. Variations at constant thermal pressure are probably a subset of the ensemble of total-pressure balanced structures, corresponding to cases in which the magnetic field magnitude does not vary appreciably throughout the structure. In this case the pressure equilibrium has to be assured by its thermal component only. The variations may be related to small flow-tubes with approximately the same magnetic-field intensity, convected by the wind in conditions of pressure equilibrium. This feature is mainly observed in low-velocity solar wind, in agreement with the magnetic topology (small open flow-tubes emerging through an ensemble of closed structures expected for the source region of slow wind. Variations of adiabatic type may be related to magnetosonic waves excited by pressure imbalances between contiguous flow-tubes. Such imbalances are probably built up by interactions between wind flows with different speeds in the spiral geometry induced by the solar rotation. This may account for the fact that they are mainly found at a large distance from the sun. Temperature variations at almost constant density are mostly found in fast flows close to the sun. These are the solar wind regions with the best examples of incompressible behaviour. They are characterized by very stable

  9. Measuring the Turbulent Cascade in the Solar Wind

    Science.gov (United States)

    MacBride, B. T.; Forman, M. A.; Smith, C. W.

    2006-12-01

    Kolmogorov's famous 4/5 law for the Navier-Stokes equation states that in isotropic hydrodynamic (HD) turbulence, the third moment of longitudinal velocity fluctuations at a spatial distance L is (4/5) ɛ ěrt L ěrt where ɛ is the turbulent energy cascade rate = heating rate per unit mass. A definite, signed, third moment is a fundamental property of the turbulent velocity fluctuations arising from the non-linear term in the Navier-Stokes equation, the only direct indicator that a cascade exists, the only measure of what direction that cascade takes (to smaller or larger spatial scales), and the truest indication of the cascade rate. The solar wind is MHD, however, and its turbulence is anisotropic. Dasso et al. (2005) perform a study on the anisotropy in the solar wind as a function of flow speed and find that there exists "quasi-two-dimensional" turbulence in low speed streams and a one dimensional "slab" structure in high speed flow. Politano and Pouquet (1998; PP) have derived an exact expression, valid in anisotropic situations, for the divergence with lag vector L of a certain vector third moment of the fluctuations in the Elsasser variables as a function of L. We perform an analysis of the third-order moment derived by PP. We use 8 years of ACE combine 64-s magnetic field and plasma measurements in variably defined subsets to compute the Elsasser variables in mean-field coordinates for different solar wind conditions (high/low wind speed, yearly, etc.). Most significantly, we attempt to separately resolve parallel and perpendicular cascades relative to the mean magnetic field. We find (1) the third moment structure functions are approximately proportional to lag as expected, (2) the inferred energy dissipation rate for outward-moving waves is larger than for inward-moving waves with many intervals showing evidence of an inverse cascade of the minority component, (3) the total energy-dissipation rate inferred by this method is frequently in disagreement

  10. On arc-polarized structures in the solar wind

    Directory of Open Access Journals (Sweden)

    B. U. Ö. Sonnerup

    2010-06-01

    Full Text Available A theoretical model is proposed to account for some of the behavior of arc-polarized magnetic structures seen in the solar wind. To this end, an exact analytical solution is developed that describes infinite plane wave trains of arbitrary amplitude in a plasma governed by ideal Hall MHD. The main focus is on intermediate-mode wave trains, which display double-branched magnetic hodogram signatures similar to those seen in the solar wind. The theoretically derived hodograms have field rotation in the ion-polarized sense at a slightly depressed field magnitude on one branch and an electron-polarized rotation at a slightly enhanced field magnitude on the other branch. The two branches are joined at the two "turning points", at which the normal flow is exactly Alfvénic. The behavior is accounted for in terms of the opposite dispersive properties of ion and electron whistlers. The hodograms derived from the theory are shown to compare favorably with those of one event, observed by the Cluster spacecraft near the ecliptic plane, and one event at high heliographic latitude observed by the Ulysses spacecraft. However, these two observed structures comprise only a single full wave period, approximately from one turning point to the other and then back again. The theory can be used to predict propagation direction (away from, or towards, the sun from magnetic data alone, provided the sign of the magnetic field component along the wave normal can be reliably determined. Under the same condition, it also predicts whether the ion-polarized branch should precede or follow the electron-polarized branch. Both behaviors are seen in the solar wind. The major shortcoming of the theory is that it fails to reproduce the observed saw-tooth like time series for the magnetic field, in which the field rotation is rapid in the ion sense and slow in the electron sense. Instead, the theory gives about the same rotation rates. Possible explanations for this discrepancy are

  11. Jumps of the solar wind direction and the substorm probability

    Science.gov (United States)

    Kubyshkina, Daria; Kubyshkina, Marina; Semenov, Vladimir

    2015-04-01

    Magnetospheric substorm commonly supposed to consist of two stages, loading and unloading. During the first stage the magnetic energy is stored in the magnetotail, which leads to increasing of the magnetic field intensity in the lobes and electric currents in the plasma sheet. The next uloading stage usually related to the reconnection process, which releases accumulated magnetic energy and produces the bursty bulk flows (BBFs) in the magnetotail. Such a scheme has been confirmed from both experimental and theoretical points of view. The weakest point of this scheme is the physical conditions which are necessary for the onset of the reconnection, but although the huge number of investigations was made to this end. Among them substorm triggers such as pressure pulses, turning of the interplanetary magnetic field (IMF) to the north direction and so on. We would like to emphasize the role of the bent current sheets first proposed by Kivelson and Hughes in 1990. The idea is that in the asymmetric configurations gradients and current density growth, so these conditions are supposed to be favorable for the reconnection. Then the minimal stress of the system can lead to the substorm onset. In the presented study we have analyzed the possibility of the current sheet asymmetry to be the trigger in theory and in observations (by statistical analysis of substorm occurrences). The bent of the current sheet can be produced by different sources. The most evident of them are the dipole tilt angle variations and the changes of the solar wind direction. The first source, tilt variations, are slow, so in the current study we at first analyzed the fast changes of the solar wind. The experimental analysis includes the investigation of the number of the events against dipole tilt angle and the solar wind direction, which both produce the distortion and inclination of the dipole current sheet. Theoretical investigation of this issue is based on the analysis of the quasi

  12. On reflection of Alfven waves in the solar wind

    Science.gov (United States)

    Krogulec, M.; Musielak, Z. E.; Suess, S. T.; Moore, R. L.; Nerney, S. F.

    1993-01-01

    We have revisited the problem of propagation of toroidal and linear Alfven waves formulated by Heinemann and Olbert (1980) to compare WKB and non-WKB waves and their effects on the solar wind. They considered two solar wind models and showed that reflection is important for Alfven waves with periods of the order of one day and longer, and that non-WKB Alfven waves are no more effective in accelerating the solar wind than WKB waves. There are several recently published papers which seem to indicate that Alfven waves with periods of the order of several minutes should be treated as non-WKB waves and that these non-WKB waves exert a stronger acceleration force than WKB waves. The purpose of this paper is to study the origin of these discrepancies by performing parametric studies of the behavior of the waves under a variety of different conditions. In addition, we want to investigate two problems that have not been addressed by Heinemann and Olbert, namely, calculate the efficiency of Alfven wave reflection by using the reflection coefficient and identify the region of strongest wave reflection in different wind models. To achieve these goals, we investigated the influence of temperature, electron density distribution, wind velocity and magnetic field strength on the waves. The obtained results clearly demonstrate that Alfven wave reflection is strongly model dependent and that the strongest reflection can be expected in models with the base temperatures higher than 10(exp 6) K and with the base densities lower than 7 x 10(exp 7) cm(exp -3). In these models as well as in the models with lower temperatures and higher densities, Alfven waves with periods as short as several minutes have negligible reflection so that they can be treated as WKB waves; however, for Alfven waves with periods of the order of one hour or longer reflection is significant, requiring a non-WKB treatment. We also show that non-WKB, linear Alfven waves are always less effective in accelerating the

  13. Kinetic Signatures and Intermittent Turbulence in the Solar Wind Plasma

    CERN Document Server

    Osman, K T; Hnat, B; Chapman, S C

    2012-01-01

    A connection between kinetic processes and intermittent turbulence is observed in the solar wind plasma using measurements from the Wind spacecraft at 1 AU. In particular, kinetic effects such as temperature anisotropy and plasma heating are concentrated near coherent structures, such as current sheets, which are non-uniformly distributed in space. Furthermore, these coherent structures are preferentially found in plasma unstable to the mirror and firehose instabilities. The inhomogeneous heating in these regions, which is present in both the magnetic field parallel and perpendicular temperature components, results in protons at least 3--4 times hotter than under typical stable plasma conditions. These results offer a new understanding of kinetic processes in a turbulent regime, where linear Vlasov theory is not sufficient to explain the inhomogeneous plasma dynamics operating near non-Gaussian structures.

  14. Alleviating alpha quenching by solar wind and meridional flow

    CERN Document Server

    Mitra, Dhrubaditya; Tavakol, Reza; Brandenburg, Axel

    2010-01-01

    We study the ability of magnetic helicity expulsion to alleviate catastrophic $\\alpha$-quenching in mean field dynamos in two--dimensional spherical wedge domains. Motivated by the physical state of the outer regions of the Sun, we consider $\\alpha^2\\Omega$ mean field models with a dynamical $\\alpha$ quenching. We include two mechanisms which have the potential to facilitate helicity expulsion, namely advection by a mean flow (``solar wind'') and meridional circulation. We find that a wind alone can prevent catastrophic quenching, with the field saturating at finite amplitude. In certain parameter ranges, the presence of a large-scale meridional circulation can reinforce this alleviation. However, the saturated field strengths are typically below the equipartition field strength. We discuss possible mechanisms that might increase the saturated field.

  15. Alleviating α quenching by solar wind and meridional flows

    Science.gov (United States)

    Mitra, D.; Moss, D.; Tavakol, R.; Brandenburg, A.

    2011-02-01

    Aims: We study the ability of magnetic helicity expulsion to alleviate catastrophic α-quenching in mean field dynamos in two-dimensional spherical wedge domains. Methods: Motivated by the physical state of the outer regions of the Sun, we consider α^2Ω mean field models with a dynamical α quenching. We include two mechanisms which have the potential to facilitate helicity expulsion, namely advection by a mean flow ("solar wind") and meridional circulation. Results: We find that a wind alone can prevent catastrophic quenching, with the field saturating at finite amplitude. In certain parameter ranges, the presence of a large-scale meridional circulation can reinforce this alleviation. However, the saturated field strengths are typically below the equipartition field strength. We discuss possible mechanisms that might increase the saturated field.

  16. Observations of the velocity distribution of solar wind ions

    Science.gov (United States)

    Ogilvie, K. W.; Bochsler, P.; Geiss, J.; Coplan, M. A.

    1980-01-01

    Measurements made by the Isee 3 ion composition experiment have been used to determine the kinetic temperatures of 3He(++), 4He(++), 16O(6+), and 16O(7+) in the solar wind. It is found that these temperatures generally obey the relation that T(i)/m(i) equals const, but fluctuations, some of which are caused by dynamical effects in the flow, are observed. The temperature of oxygen sometimes rises above 10 K, which is very strong evidence for heating outside the collisional region of the corona. The tendency toward equal temperatures per nucleon occurs everywhere where collisions are unimportant, suggesting that the temperatures are set up close to the sun rather than elsewhere in the interplanetary medium. The velocity distribution function of helium is observed to be non-Maxwellian, with a pronounced high velocity tail.

  17. The relation of solar wind structure to hydromagnetic discontinuities

    Energy Technology Data Exchange (ETDEWEB)

    Alexander, C.J.; Neugebauer, M.; Smith, E.J.; Bame, S.J.

    1987-01-01

    High resolution ISEE-3 data have been used to examine the relative abundances of tangential (TD) vs rotational (RD) discontinuities in different types of solar wind flow. Three types of flow were examined; flow from coronal holes, sector boundary flow and transient flow. It has been found that coronal hole flow has substantially more discontinuities and a greater ratio of RD's to TD's than do the other types of flow. Discontinuities are least frequent in transient flows characterized by bidirectional streaming of electrons. This leads us to the conclusion that meaningful studies of the velocity dependence of the rates of occurrence of different types of discontinuities must take the type of flow (coronal hole versus transient) into account. 7 refs., 3 figs., 1 tab.

  18. The origins of planar magnetic structures in the solar wind

    Energy Technology Data Exchange (ETDEWEB)

    Neugebauer, M.; Clay, D.R. (California Inst. of Technology, Pasadena (United States)); Gosling, J.T. (Los Alamos National Lab., NM (United States))

    1993-06-01

    The authors report on an assessment of extensive solar wind and interplanetary magnetic field (IMF) data obtained by ISEE-3, between Aug 1978 and Oct 1982, when it was upstream of the earth's bow shock. They looked for events given the name planar magnetic structure (PMS). A PMS event is a series of abrupt changes in the IMF, where the magnetic field is observed to take almost all values in some plane. Numerous possible explanations have been offered for these phenomena, and the authors looked at this data set to see if it would aid in the understanding of the origin of PMS. They observed the PMS events to generally be associated with two events: they tended to occur near the interplanetary current sheet, or; they tended to occur in the sheath of the wind plasma between an interplanetary shock, and the plasma which drove it.

  19. Electromagnetic lower hybrid instability in the solar wind

    Energy Technology Data Exchange (ETDEWEB)

    Lakhina, G.S.

    1985-04-01

    A fully electromagnetic lower hybrid instability which is driven by a resonant halo electron component is studied analytically. It is shown that the growth rate of the instability peaks at a certain value of the wave-number and that an increase in the ratio of electron pressure to magnetic field pressure reduces the growth rate. At 0.3 AU the typical growth time for the instability is found to be of the order of 25 ms or less, whereas the most unstable wavelengths associated with the instability fall typically in a range of 27 to 90 km. Relevance of electromagnetic lower hybrid instability to the obliquely propagating whistler, characterized by large values of refractive indices, detected behind interplanetary shocks in the solar wind and to the generation mechanism of correlated whistler and electron-plasma oscillation bursts detected on ISEE-3 are discussed. 17 references.

  20. EMMI-Electric solar wind sail facilitated Manned Mars Initiative

    Science.gov (United States)

    Janhunen, Pekka; Merikallio, Sini; Paton, Mark

    2015-08-01

    The novel propellantless electric solar wind sail concept promises efficient low thrust transportation in the Solar System outside Earth's magnetosphere. Combined with asteroid mining to provide water and synthetic cryogenic rocket fuel in orbits of Earth and Mars, possibilities for affordable continuous manned presence on Mars open up. Orbital fuel and water enable reusable bidirectional Earth-Mars vehicles for continuous manned presence on Mars and allow smaller fuel fraction of spacecraft than what is achievable by traditional means. Water can also be used as radiation shielding of the manned compartment, thus reducing the launch mass further. In addition, the presence of fuel in the orbit of Mars provides the option for an all-propulsive landing, thus potentially eliminating issues of heavy heat shields and augmenting the capability of pinpoint landing. With this E-sail enabled scheme, the recurrent cost of continuous bidirectional traffic between Earth and Mars might ultimately approach the recurrent cost of running the International Space Station, ISS.

  1. Three-Dimensional Structure of Solar Wind Turbulence

    CERN Document Server

    Chen, C H K; Schekochihin, A A; Horbury, T S; Wicks, R T; Bale, S D

    2011-01-01

    We have measured, for the first time, the three-dimensional structure of inertial range plasma turbulence in the fast solar wind with respect to a local, physically motivated coordinate system. We found that the incompressible Alfvenic fluctuations are three-dimensionally anisotropic, with the sense of this anisotropy changing from large to small scales. At the largest scales, the magnetic field correlations are longest in the local fluctuation direction, consistent with Alfven waves. At the smallest scales, they are longest along the local mean field direction and shortest in the direction perpendicular to the local mean field and the local field fluctuation. The compressive fluctuations are highly elongated along the local mean magnetic field direction, although axially symmetric perpendicular to it. Their large anisotropy may explain why they are not heavily damped.

  2. Kinetic Scale Density Fluctuations in the Solar Wind

    CERN Document Server

    Chen, C H K; Bonnell, J W; Mozer, F S; Klein, K G; Bale, S D

    2013-01-01

    We motivate the importance of studying kinetic scale turbulence for understanding the macroscopic properties of the heliosphere, such as the heating of the solar wind. We then discuss the technique by which kinetic scale density fluctuations can be measured using the spacecraft potential, including a calculation of the timescale for the spacecraft potential to react to the density changes. Finally, we compare the shape of the density spectrum at ion scales to theoretical predictions based on a cascade model for kinetic turbulence. We conclude that the shape of the spectrum, including the ion scale flattening, can be captured by the sum of passive density fluctuations at large scales and kinetic Alfven wave turbulence at small scales.

  3. The role of electrons at the solar wind termination shock

    Energy Technology Data Exchange (ETDEWEB)

    Fahr, Hans Joerg; Siewert, Mark [Argelander Institut fuer Astronomie, Universitaet Bonn, Auf dem Huegel 71, 53121 Bonn (Germany)

    2013-07-01

    Describing the solar wind termination shock as a multi-fluid MHD Rankine-Hugoniot shock structure, it is usually assumed that electrons and protons experience identical jumps in density and pressure at the plasma passage over the shock. When analysing the specific kinetic conditions for electrons and ions at this MHD shock crossing, we find that electrons react very much different from protons at their shock passage undergoing an over-adiabatic heating due to conversion of electrically induced overshoot energies into downstream thermal energies. In case of an electron-proton two-fluid plasma, electrons constitute the dominant contribution to the downstream thermal plasma pressure and thereby determine the resulting compression ratio at the shock. We show that taking this over-adiabatic electron heating into account will then deliver a correct representation of all shock data taken with VOYAGER-2.

  4. Recent progress in astrophysical plasma turbulence from solar wind observations

    CERN Document Server

    Chen, C H K

    2016-01-01

    This paper summarises some of the recent progress that has been made in understanding astrophysical plasma turbulence in the solar wind, from in situ spacecraft observations. At large scales, where the turbulence is predominantly Alfvenic, measurements of critical balance, residual energy, and 3D structure are discussed, along with comparison to recent models of strong Alfvenic turbulence. At these scales, a few percent of the energy is also in compressive fluctuations, and their nature, anisotropy, and relation to the Alfvenic component is described. In the small scale kinetic range, below the ion gyroscale, the turbulence becomes predominantly kinetic Alfven in nature, and measurements of the spectra, anisotropy, and intermittency of this turbulence are discussed with respect to recent cascade models. One of the major remaining questions is how the turbulent energy is dissipated, and some recent work on this question, in addition to future space missions which will help to answer it, are briefly discussed.

  5. From the Solar Wind to the Magnetospheric Substorm

    Institute of Scientific and Technical Information of China (English)

    E.A. Ponomarev; P.A. Sedykh; O.V. Mager

    2005-01-01

    This paper gives a brief outline of the progression from the first substorm model developed in Ref.[4] and [8] based on Kennel's ideas[3], to the present views about the mechanism by which solar wind kinetic energy is converted to electromagnetic energy at the Bow Shock and by which this energy is transferred to the magnetosphere in the form of current; about the transformation of the energy of this current to gas kinetic energy of convecting plasma tubes, and, finally, the back transformation of gas kinetic energy to electromagnetic energy in secondary magnetospheric MHD generators. The questions of the formation of the magnetospheric convection system, the nature of substorm break-up, and of the matching of currents in the magnetosphere-ionosphere system are discussed.

  6. Solar Wind Strahl Broadening by Self-Generated Plasma Waves

    Science.gov (United States)

    Pavan, J.; Vinas, A. F.; Yoon, P. H.; Ziebell, L. F.; Gaelzer, R.

    2013-01-01

    This Letter reports on the results of numerical simulations which may provide a possible explanation for the strahl broadening during quiet solar conditions. The relevant processes involved in the broadening are due to kinetic quasi-linear wave-particle interaction. Making use of static analytical electron distribution in an inhomogeneous field, it is found that self-generated electrostatic waves at the plasma frequency, i.e., Langmuir waves, are capable of scattering the strahl component, resulting in energy and pitch-angle diffusion that broadens its velocity distribution significantly. The present theoretical results provide an alternative or complementary explanation to the usual whistler diffusion scenario, suggesting that self-induced electrostatic waves at the plasma frequency might play a key role in broadening the solar wind strahl during quiet solar conditions.

  7. Kinetic signatures and intermittent turbulence in the solar wind plasma.

    Science.gov (United States)

    Osman, K T; Matthaeus, W H; Hnat, B; Chapman, S C

    2012-06-29

    A connection between kinetic processes and intermittent turbulence is observed in the solar wind plasma using measurements from the Wind spacecraft at 1 A.U. In particular, kinetic effects such as temperature anisotropy and plasma heating are concentrated near coherent structures, such as current sheets, which are nonuniformly distributed in space. Furthermore, these coherent structures are preferentially found in plasma unstable to the mirror and firehose instabilities. The inhomogeneous heating in these regions, which is present in both the magnetic field parallel and perpendicular temperature components, results in protons at least 3-4 times hotter than under typical stable plasma conditions. These results offer a new understanding of kinetic processes in a turbulent regime, where linear Vlasov theory is not sufficient to explain the inhomogeneous plasma dynamics operating near non-Gaussian structures.

  8. EMMI - Electric Solar Wind Sail Facilitated Manned Mars Initiative

    CERN Document Server

    Janhunen, Pekka; Paton, Mark

    2014-01-01

    The novel propellantless electric solar wind sail (E-sail) concept promises efficient low thrust transportation in the solar system outside Earth's magnetosphere. Combined with asteroid mining to provide water and synthetic cryogenic rocket fuel in orbits of Earth and Mars, possibilities for affordable continuous manned presence on Mars open up. Orbital fuel and water eliminate the exponential nature of the rocket equation and also enable reusable bidirectional Earth-Mars vehicles for continuous manned presence on Mars. Water can also be used as radiation shielding of the manned compartment, thus reducing the launch mass further. In addition, the presence of fuel in Mars orbit provides the option for an all-propulsive landing, thus potentially eliminating issues of heavy heat shields and augmenting the capability of pinpoint landing. With this E-sail enabled scheme, the recurrent cost of continuous bidirectional traffic between Earth and Mars might ultimately approach the recurrent cost of running the Interna...

  9. NEW MODEL OF A SOLAR WIND AIRPLANE FOR GEOMATIC OPERATIONS

    Directory of Open Access Journals (Sweden)

    A. Achachi

    2015-08-01

    Full Text Available The ability for an aircraft to fly during a much extended period of time has become a key issue and a target of research, both in the domain of civilian aviation and unmanned aerial vehicles. This paper describes a new design and evaluating of solar wind aircraft with the objective to assess the impact of a new system design on overall flight crew performance. The required endurance is in the range of some hours in the case of law enforcement, border surveillance, forest fire fighting or power line inspection. However, other applications at high altitudes, such as geomatic operations for delivering geographic information, weather research and forecast, environmental monitoring, would require remaining airborne during days, weeks or even months. The design of GNSS non precision approach procedure for different airports is based on geomatic data.

  10. Reconnection outflow generated turbulence in the solar wind

    CERN Document Server

    Vörös, Z; Semenov, V S; Zaqarashvili, T V; Bruno, R; Khodachenko, M

    2014-01-01

    Petschek-type time-dependent reconnection (TDR) and quasi-stationary reconnection (QSR) models are considered to understand reconnection outflow structures and the features of the associated locally generated turbulence in the solar wind. We show that the outflow structures, such as discontinuites, Kelvin-Helmholtz (KH) unstable flux tubes or continuous space filling flows cannot be distinguished from one-point WIND measurements. In both models the reconnection outflows can generate more or less spatially extended turbulent boundary layers (TBDs). The structure of an unique extended reconnection outflow is investigated in detail. The analysis of spectral scalings and break locations show that reconnection outflows can control the local field and plasma conditions which may play in favor of one or another turbulent dissipation mechanisms with their characteristic scales and wavenumbers.

  11. Scaling of compressible magnetohydrodynamic turbulence in the fast solar wind

    Science.gov (United States)

    Sahraoui, F.; Banerjee, S.; Galtier, S.; Hadid, L.

    2015-12-01

    The role of compressible uctuations in the energy cascade of fast solar wind turbulence is studiedusing an exact law derived recently for compressible isothermal magnetohydrodynamics and in-situobservations of the THEMIS spacecraft. For the first time, a direct turbulent energy cascade isevidenced over three decades of scales which is signicantly broader than the previous estimatesmade from an exact incompressible law or from a compressible heuristic model. Unlike previousworks, our evaluation gives an energy ux which keeps a constant sign over the inertial range. Aterm-by-term analysis reveals that the dominant contribution to the energy ux comes from purecompressible uctuations. Furthermore, the compressible turbulent cascade rate is shown to providethe adequate energy dissipation required to account for the local heating of the non-adiabatic solarwind.

  12. Chaos and periodicity in solar wind speed: cycle 23

    Science.gov (United States)

    Sarkar, Tushnik; Ray, Rajdeep; Khondekar, Mofazzal H.; Ghosh, Koushik; Banerjee, Subrata

    2015-06-01

    The solar wind speed time series data from 1st January, 1997 to 28th October, 2003 has been pre-processed using simple exponential smoothing, discrete wavelet transform for denoising to investigate the underneath dynamics of it. Recurrence plot and recurrence quantification analysis has revealed that the time series is non-stationary one with deterministic chaotic behavior. The Hilbert-Huang Transform has been used in search of the underlying periods of the data series. Present investigation has revealed the periods of 21 days, 32.5 days, 43.6 days, 148.86 days, 180.7 days, 355.5 days, 403.2 days, 413.6 days, 490.72 days, 729.6 days, 1086.76 days, 1599.4 days and 1892.6 days.

  13. Energetic particles as probes of solar wind disturbances

    Energy Technology Data Exchange (ETDEWEB)

    Cane, H.V.; Richardson, I.G.; Wibberenz, G.

    1995-06-01

    The authors have investigated the response of particles, in the energy range approximately 1-5000 MeV, to interplanetary shocks and coronal ejecta. Shocks can accelerate particles or cause decreases in particle densities. Ejecta cause decreases. Thus particle observations can provide information about solar wind disturbances. Of particular interest is that the boundaries of ejecta can often be more readily identified from approximately l GeV particle decrease observations than from most other phenomena associated with ejecta. The authors will discuss the properties of less energetic shocks and ejecta and compare them with those of the more energetic events which are normally discussed in the context of Forbush decreases, large proton events, etc. They use data from both Helios spacecraft and IMP 8 which allows some spatial variations to be studied.

  14. Simulation and optimum design of hybrid solar-wind and solar-wind-diesel power generation systems

    Science.gov (United States)

    Zhou, Wei

    Solar and wind energy systems are considered as promising power generating sources due to its availability and topological advantages in local power generations. However, a drawback, common to solar and wind options, is their unpredictable nature and dependence on weather changes, both of these energy systems would have to be oversized to make them completely reliable. Fortunately, the problems caused by variable nature of these resources can be partially overcome by integrating these two resources in a proper combination to form a hybrid system. However, with the increased complexity in comparison with single energy systems, optimum design of hybrid system becomes more complicated. In order to efficiently and economically utilize the renewable energy resources, one optimal sizing method is necessary. This thesis developed an optimal sizing method to find the global optimum configuration of stand-alone hybrid (both solar-wind and solar-wind-diesel) power generation systems. By using Genetic Algorithm (GA), the optimal sizing method was developed to calculate the system optimum configuration which offers to guarantee the lowest investment with full use of the PV array, wind turbine and battery bank. For the hybrid solar-wind system, the optimal sizing method is developed based on the Loss of Power Supply Probability (LPSP) and the Annualized Cost of System (ACS) concepts. The optimization procedure aims to find the configuration that yields the best compromise between the two considered objectives: LPSP and ACS. The decision variables, which need to be optimized in the optimization process, are the PV module capacity, wind turbine capacity, battery capacity, PV module slope angle and wind turbine installation height. For the hybrid solar-wind-diesel system, minimization of the system cost is achieved not only by selecting an appropriate system configuration, but also by finding a suitable control strategy (starting and stopping point) of the diesel generator. The

  15. Non-Gaussian probability distributions of solar wind fluctuations

    Directory of Open Access Journals (Sweden)

    E. Marsch

    Full Text Available The probability distributions of field differences ∆x(τ=x(t+τ-x(t, where the variable x(t may denote any solar wind scalar field or vector field component at time t, have been calculated from time series of Helios data obtained in 1976 at heliocentric distances near 0.3 AU. It is found that for comparatively long time lag τ, ranging from a few hours to 1 day, the differences are normally distributed according to a Gaussian. For shorter time lags, of less than ten minutes, significant changes in shape are observed. The distributions are often spikier and narrower than the equivalent Gaussian distribution with the same standard deviation, and they are enhanced for large, reduced for intermediate and enhanced for very small values of ∆x. This result is in accordance with fluid observations and numerical simulations. Hence statistical properties are dominated at small scale τ by large fluctuation amplitudes that are sparsely distributed, which is direct evidence for spatial intermittency of the fluctuations. This is in agreement with results from earlier analyses of the structure functions of ∆x. The non-Gaussian features are differently developed for the various types of fluctuations. The relevance of these observations to the interpretation and understanding of the nature of solar wind magnetohydrodynamic (MHD turbulence is pointed out, and contact is made with existing theoretical concepts of intermittency in fluid turbulence.

  16. Moving an asteroid with electric solar wind sail

    Science.gov (United States)

    Merikallio, S.; Janhunen, P.

    2010-12-01

    The electric solar wind sail (E-Sail) is a new propulsion method for interplanetary travel which was invented in 2006 and is currently under development. The E-Sail uses charged tethers to extract momentum from the solar wind particles to obtain propulsive thrust. According to current estimates, the E-Sail is 2-3 orders of magnitude better than traditional propulsion methods (chemical rockets and ion engines) in terms of produced lifetime-integrated impulse per propulsion system mass. Here we analyze the problem of using the E-Sail for directly deflecting an Earth-threatening asteroid. The problem then culminates into how to attach the E-Sail device to the asteroid. We assess alternative attachment strategies, namely straightforward direct towing with a cable and the gravity tractor method which works for a wider variety of situations. We also consider possible techniques to scale up the E-Sail force beyond the baseline one Newton level to deal with more imminent or larger asteroid or cometary threats. As a baseline case we consider an asteroid of effective diameter of 140 m and mass of 3 million tons, which can be deflected with a baseline 1 N E-Sail within 10 years. With a 5 N E-Sail the deflection could be achieved in 5 years. Once developed, the E-Sail would appear to provide a safe and reasonably low-cost way of deflecting dangerous asteroids and other heavenly bodies in cases where the collision threat becomes known several years in advance.

  17. A Model for the Sources of the Slow Solar Wind

    Science.gov (United States)

    Antiochos, Spiro K.; Mikic, Z.; Titov, V. S.; Lionello, R.; Linker, J. A.

    2010-01-01

    Models for the origin of the slow solar wind must account for two seemingly contradictory observations: The slow wind has the composition of the closed-field corona, implying that it originates from the continuous opening and closing of flux at the boundary between open and closed field. On the other hand, the slow wind has large angular width, up to approximately 60 degrees, suggesting that its source extends far from the open-closed boundary. We propose a model that can explain both observations. The key idea is that the source of the slow wind at the Sun is a network of narrow (possibly singular) open-field corridors that map to a web of separatrices and quasi-separatrix layers in the heliosphere. We compute analytically the topology of an open-field corridor and show that it produces a quasi-separatrix layer in the heliosphere that extends to angles far front the heliospheric current sheet. We then use an MHD code and MIDI/SOHO observations of the photospheric magnetic field to calculate numerically, with high spatial resolution, the quasi-steady solar wind and magnetic field for a time period preceding the August 1, 2008 total solar eclipse. Our numerical results imply that, at least for this time period, a web of separatrices (which we term an S-web) forms with sufficient density and extent in the heliosphere to account for the observed properties of the slow wind. We discuss the implications of our S-web model for the structure and dynamics of the corona and heliosphere, and propose further tests of the model.

  18. Scale Dependence of Magnetic Helicity in the Solar Wind

    Science.gov (United States)

    Brandenburg, Axel; Subramanian, Kandaswamy; Balogh, Andre; Goldstein, Melvyn L.

    2011-01-01

    We determine the magnetic helicity, along with the magnetic energy, at high latitudes using data from the Ulysses mission. The data set spans the time period from 1993 to 1996. The basic assumption of the analysis is that the solar wind is homogeneous. Because the solar wind speed is high, we follow the approach first pioneered by Matthaeus et al. by which, under the assumption of spatial homogeneity, one can use Fourier transforms of the magnetic field time series to construct one-dimensional spectra of the magnetic energy and magnetic helicity under the assumption that the Taylor frozen-in-flow hypothesis is valid. That is a well-satisfied assumption for the data used in this study. The magnetic helicity derives from the skew-symmetric terms of the three-dimensional magnetic correlation tensor, while the symmetric terms of the tensor are used to determine the magnetic energy spectrum. Our results show a sign change of magnetic helicity at wavenumber k approximately equal to 2AU(sup -1) (or frequency nu approximately equal to 2 microHz) at distances below 2.8AU and at k approximately equal to 30AU(sup -1) (or nu approximately equal to 25 microHz) at larger distances. At small scales the magnetic helicity is positive at northern heliographic latitudes and negative at southern latitudes. The positive magnetic helicity at small scales is argued to be the result of turbulent diffusion reversing the sign relative to what is seen at small scales at the solar surface. Furthermore, the magnetic helicity declines toward solar minimum in 1996. The magnetic helicity flux integrated separately over one hemisphere amounts to about 10(sup 45) Mx(sup 2) cycle(sup -1) at large scales and to a three times lower value at smaller scales.

  19. High-latitude Conic Current Sheets in the Solar Wind

    Science.gov (United States)

    Khabarova, Olga V.; Malova, Helmi V.; Kislov, Roman A.; Zelenyi, Lev M.; Obridko, Vladimir N.; Kharshiladze, Alexander F.; Tokumaru, Munetoshi; Sokół, Justyna M.; Grzedzielski, Stan; Fujiki, Ken'ichi

    2017-02-01

    We provide observational evidence for the existence of large-scale cylindrical (or conic-like) current sheets (CCSs) at high heliolatitudes. Long-lived CCSs were detected by Ulysses during its passages over the South Solar Pole in 1994 and 2007. The characteristic scale of these tornado-like structures is several times less than a typical width of coronal holes within which the CCSs are observed. CCS crossings are characterized by a dramatic decrease in the solar wind speed and plasma beta typical for predicted profiles of CCSs. Ulysses crossed the same CCS at different heliolatitudes at 2-3 au several times in 1994, as the CCS was declined from the rotation axis and corotated with the Sun. In 2007, a CCS was detected directly over the South Pole, and its structure was strongly highlighted by the interaction with comet McNaught. Restorations of solar coronal magnetic field lines reveal the occurrence of conic-like magnetic separators over the solar poles in both 1994 and 2007. Such separators exist only during solar minima. Interplanetary scintillation data analysis confirms the presence of long-lived low-speed regions surrounded by the typical polar high-speed solar wind in solar minima. Energetic particle flux enhancements up to several MeV/nuc are observed at edges of the CCSs. We built simple MHD models of a CCS to illustrate its key features. The CCSs may be formed as a result of nonaxiality of the solar rotation axis and magnetic axis, as predicted by the Fisk-Parker hybrid heliospheric magnetic field model in the modification of Burger and coworkers.

  20. Access of solar wind electrons into the Martian magnetosphere

    Directory of Open Access Journals (Sweden)

    E. M. Dubinin

    2008-11-01

    Full Text Available Electrons with energy of ~40–80 eV measured by the instrument ASPERA-3 on Mars Express and MAG-ER onboard Mars Global Surveyor are used to trace an access of solar wind electrons into the Martian magnetosphere. Crustal magnetic fields create an additional protection from solar wind plasma on the dayside of the Southern Hemisphere by shifting the boundary of the induced magnetosphere (this boundary is often refereed as the magnetic pileup boundary above strong crustal sources to ~400 km as compared to the Northern Hemisphere. Localized intrusions through cusps are also observed. On the nightside an access into the magnetosphere depends on the IMF orientation. Negative values of the ByIMF component assist the access to the regions with strong crustal magnetizations although electron fluxes are strongly weakened below ~600 km. A precipitation pattern at lower altitudes is formed by intermittent regions with reduced and enhanced electron fluxes. The precipitation sites are longitudinally stretched narrow bands in the regions with a strong vertical component of the crustal field. Fluxes ≥109 cm−2 s−1 of suprathermal electrons necessary to explain the observed aurora emissions are maintained only for the periods with enhanced precipitation. The appearance of another class of electron distributions – inverted V structures, characterized by peaks on energy spectra, is controlled by the IMF. They are clustered in the hemisphere pointed by the interplanetary electric field that implies a constraint on their origin.

  1. Saturn's Auroral Response to the Solar Wind: Centrifugal Instability Model

    Science.gov (United States)

    Sittler, Edward C.; Blanc, Michel F.; Richardson, J. D.

    2008-01-01

    We describe a model initially presented by Sittler et al. [2006] which attempts to explain the global response of Saturn's magnetosphere and its corresponding auroral behavior to variations in the solar wind. The model was derived from published simultaneous Hubble Space Telescope (HST) auroral images and Cassini upstream measurements taken during the month of January 2004. These observations show a direct correlation between solar wind dynamic pressure and (1) auroral brightening toward dawn local time, (2) an increase of rotational movement of auroral features to as much as 75% of the corotation speed, (3) the movement of the auroral oval to higher latitudes and (4) an increase in the intensity of Saturn Kilometric Radiation (SKR). This model is an alternative to the reconnection model of Cowley et al. [2004a,b; 2005] which is more Earth-like while ours stresses rotation. If angular momentum is conserved in a global sense, then when compressed the magnetosphere will tend to spin up and when it expands will tend to spin down. With the plasma sheet outer boundary at L approximates 15 we argue this region to be the dominant source region for the precipitating particles. If radial transport is dominated by centrifugal driven flux tube interchange motions, then when the magnetosphere spins up, outward transport will increase, the precipitating particles will move radially outward and cause the auroral oval to move to higher latitudes as observed. The Kelvin-Helmholtz instability may contribute to the enhanced emission along the dawn meridian as observed by HST. We present this model in the context of presently published observations by Cassini.

  2. Transport of Solar Wind Across Earth's Bow Shock

    Science.gov (United States)

    Parks, G. K.; Lee, E.; Yang, Z.; Liu, Y.; Fu, S.; Canu, P.; Goldstein, M. L.; Dandouras, I. S.; Reme, H.; Hong, J.

    2015-12-01

    Observations have established that about 20% of the solar wind (SW) is reflected and 80% directly transmitted across Earth's bow shock (Skopke et al, Adv. Space Sci., 15, No. 8/9, 269, 1995). The transmitted SW is not immediately thermalized and the magnetosheath plasma distribution can remain non-Maxwellian for a long time. Cluster observations have further established that most of the magnetosheath bulk flow remains super-Alfvenic except in the polar altitudes near the cusp region (Longmore et al., Anna. Geophysicae, 23, 3351-3364, 2005). We have studied SW ion distributions before and after entering the bow shock to examine the details of the solar wind-bow shock interaction. Preliminary findings indicate that a typical SW H+ beam with thermal kT ~10 eV drifting at 400 km/s in front of the bow shock appears as ~12 eV beam drifting at 250 km/s after it penetrates the shock barrier. The small kT increase is possibly due to wave-particle interaction at the boundary. While the He++ ion beam kT behaves similarly as H+ ions, the drift velocities of He++ ions do not always slow down as H+ ions. These observations indicate the physics of SW-bow shock interaction is much more complicated than the models that explain SW slow down as resulting from an electrostatic potential at the shock that decelerates the SW. We have started PIC simulation of SW transport across the bow shock and the results will be presented together with observations.

  3. Differential Velocity between Solar Wind Protons and Alpha Particles in Pressure Balance Structures

    Science.gov (United States)

    Yamauchi, Yohei; Suess, Steven T.; Steinberg, John T.; Sakurai, Takashi

    2004-01-01

    Pressure balance structures (PBSs) are a common high-plasma beta feature in high-latitude, high-speed solar wind. They have been proposed as remnants of coronal plumes. If true, they should reflect the observation that plumes are rooted in unipolar magnetic flux concentrations in the photosphere and are heated as oppositely directed flux is advected into and reconnects with the flux concentration. A minimum variance analysis (MVA) of magnetic discontinuities in PBSs showed there is a larger proportion of tangential discontinuities than in the surrounding high-speed wind, supporting the hypothesis that plasmoids or extended current sheets are formed during reconnection at the base of plumes. To further evaluate the character of magnetic field discontinuities in PBSs, differential streaming between alpha particles and protons is analyzed here for the same sample of PBSs used in the MVA. Alpha particles in high-speed wind generally have a higher radial flow speed than protons. However, if the magnetic field is folded back on itself, as in a large-amplitude Alfven wave, alpha particles will locally have a radial flow speed less than protons. This characteristic is used here to distinguish between folded back magnetic fields (which would contain rotational discontinuities) and tangential discontinuities using Ulysses high-latitude, high-speed solar wind data. The analysis indicates that almost all reversals in the radial magnetic field in PBSs are folded back field lines. This is found to also be true outside PBSs, supporting existing results for typical high-speed, high-latitude wind. There remains a small number of cases that appear not to be folds in the magnetic field and which may be flux tubes with both ends rooted in the Sun. The distinct difference in MVA results inside and outside PBSs remains unexplained.

  4. Development of three-dimensional magnetohydrodynamic model for solar corona and solar wind simulation

    Science.gov (United States)

    Yuan, Xingqiu; Trichtchenko, Larisa; Boteler, David

    Propagation of coronal mass ejections from solar surface to the Earth magnetosphere is strongly influenced by the conditions in solar corona and ambient solar wind. Thus, reliable simulation of the background solar wind is the primary task toward the development of numerical model for the transient events. In this paper we introduce a new numerical model which has been specifically designed for numerical study of the solar corona and ambient solar wind. This model is based on our recently developed three-dimensional Spherical Coordinate Adaptive Magneto-Hydro-Dynamic (MHD) code (SCA-MHD-3D) [Yuan et al., 2009]. Modifications has been done to include the observed magnetic field at the photosphere as inner boundary conditions. The energy source term together with reduced plasma gamma are used in the nonlinear MHD equations in order to simulate the solar wind acceleration from subsonic speed at solar surface to supersonic speed at the inter-heliosphere region, and the absorbing boundary conditions are used at the solar surface. This model has been applied to simulate the background solar wind condition for several different solar rotations, and comparison between the observation and model output have shown that it reproduces many features of solar wind, including open and closed magnetic fields, fast and slow solar wind speed, sector boundaries, etc.

  5. Statistical analysis of long-duration low-density solar wind events

    Directory of Open Access Journals (Sweden)

    S. Watari

    Full Text Available Low solar wind density with long duration was measured by in situ observation between 11 and 12 May 1999. As a result of this low-density solar wind condition, the magnetosphere of the Earth expanded considerably. We used a database of one-hour-averaged solar wind (1963–1999 near 1 AU to determine whether or not the observed low-density event was extremely abnormal. As a result it was found that this event has the longest duration in approximately 36 years of solar wind observations. There are three events with density 0.5 cm-3 or less and duration ten hours or longer. They were observed on 4 and 31 July 1979, and 11–12 May 1999. The 4 July 1979 event recurred on 31 July 1979. The events were characterized by low-beta, low Alfven Mach number (MA , and low dynamic pressure. The occurrence rate of low-density solar wind with density 0.5 cm-3 or less shows several peaks near solar maxima. However, it is difficult to find a clear relationship between the sunspot number and the occurrence rate.

    Key words. Interplanetary physics (flare and stream dynamics; solar wind plasma; sources of the solar wind

  6. The magnetic field in the pile-up region at Mars, and its variation with the solar wind

    DEFF Research Database (Denmark)

    Vennerstrøm, Susanne; Olsen, Nils; Purucker, M.

    2003-01-01

    [1] The magnetic measurements from the Mars Global Surveyor satellite are used to study the magnetic field on the Martian dayside, and its variation with the solar wind. Because of the lack of solar wind measurements near Mars, solar wind measurements near Earth during a period centered on a Mars...... the solar wind dynamic pressure and the magnetic pressure in the pile-up region, and also a strong asymmetry with the Interplanetary magnetic field (IMF) By-component, probably related to solar wind pick-up of planetary ions....

  7. The rudiments of a theory of solar wind/magnetosphere coupling derived from first principles

    Science.gov (United States)

    Borovsky, Joseph E.

    2008-08-01

    A formula that expresses the dayside reconnection rate in terms of upstream solar wind parameters is derived and tested. The derivation is based on the hypothesis that dayside reconnection is governed by local plasma parameters and that whatever controls those parameters controls the reconnection rate. The starting point of the derivation is the Cassak-Shay formula (from energy conservation principles), which expresses the dayside reconnection rate in terms of four parameters: the magnetic field strengths Bm and Bs in the magnetosphere and magnetosheath and the plasma mass densities ρm and ρs in the magnetosphere and magnetosheath. Using the Rankine-Hugoniot relations at the bow shock and an analysis of the magnetosheath flow, three of these parameters are expressed in terms of upstream solar wind parameters. These three expressions are then used in the Cassak-Shay formula to obtain the "solar wind control function." The interpretation of the control function is that solar wind pressure largely sets the reconnection rate. The solar wind magnetic field enters into the control function because of a bow shock Mach number dependence. The onset of a "plasmasphere effect" occurs when ρm > MA0.87ρsolarwind, wherein the magnetosphere begins to exert control over solar wind/magnetosphere coupling. Using the OMNI2 data set and seven geomagnetic indices, the solar wind control function is tested on its ability to describe the variance in the geomagnetic indices. The control function is found to be successful, statistically as good as the best "solar wind driver function" in the literature. This picture opens a new pathway to understanding and calculating solar wind/magnetosphere coupling.

  8. TURBULENCE IN THE SOLAR WIND MEASURED WITH COMET TAIL TEST PARTICLES

    Energy Technology Data Exchange (ETDEWEB)

    DeForest, C. E.; Howard, T. A. [Southwest Research Institute, 1050 Walnut Street Suite 300, Boulder, CO 80302 (United States); Matthaeus, W. H. [Department of Physics and Astronomy, University of Delaware, 217 Sharp Laboratory, Newark, DE 19711 (United States); Rice, D. R. [Northwestern University, 633 Clark St., Evanston, IL 60208 (United States)

    2015-10-20

    By analyzing the motions of test particles observed remotely in the tail of Comet Encke, we demonstrate that the solar wind undergoes turbulent processing enroute from the Sun to the Earth and that the kinetic energy entrained in the large-scale turbulence is sufficient to explain the well-known anomalous heating of the solar wind. Using the heliospheric imaging (HI-1) camera on board NASA's STEREO-A spacecraft, we have observed an ensemble of compact features in the comet tail as they became entrained in the solar wind near 0.4 AU. We find that the features are useful as test particles, via mean-motion analysis and a forward model of pickup dynamics. Using population analysis of the ensemble's relative motion, we find a regime of random-walk diffusion in the solar wind, followed, on larger scales, by a surprising regime of semiconfinement that we attribute to turbulent eddies in the solar wind. The entrained kinetic energy of the turbulent motions represents a sufficient energy reservoir to heat the solar wind to observed temperatures at 1 AU. We determine the Lagrangian-frame diffusion coefficient in the diffusive regime, derive upper limits for the small scale coherence length of solar wind turbulence, compare our results to existing Eulerian-frame measurements, and compare the turbulent velocity with the size of the observed eddies extrapolated to 1 AU. We conclude that the slow solar wind is fully mixed by turbulence on scales corresponding to a 1–2 hr crossing time at Earth; and that solar wind variability on timescales shorter than 1–2 hr is therefore dominated by turbulent processing rather than by direct solar effects.

  9. 3-D MHD Model of the Solar Wind-Interplanetary Space Combining System 1:Variation of Solar Wind Speed Associated with the Photospheric Magnetic Field

    Science.gov (United States)

    Nakamizo, A.; Tanaka, T.

    2006-12-01

    Existing global models of the solar-wind/IMF expanding to the Earth's orbit are basically grounded in the idea of "source surface." It is widely accepted that the sector structure and the solar wind speed are primarily controlled by the magnetic field at the source surface and the so-called "expansion factor." On the other hand, 3-D MHD model is still off from practical use because both of scientific and technical problems. One of the former problems is the reproduction of supersonic solar-wind. From the viewpoint of the physics of the solar wind, coronal heating and outward acceleration mechanisms are invoked to explain the supersonic evolution of the solar wind. Since the mechanism responsible for the heating/acceleration is still one of the primary subjects of the physics of the solar wind, many MHD models have taken into account their effects by incorporating additional source terms corresponding to promising candidates such as thermal conductions, radiation losses and wave pressures. However there are few MHD models considering the effect of the expansion factor, which determines the solar-wind speed in the series of source surface models. In this study we newly incorporate the flux tube expansion rate into the MHD equation system including heat source function in the energy equation. Appling the unstructured grid system, we achieved the dense grid spacing at the inner boundary, which enable us to adopt realistic solar magnetic fields, and a size of simulation space of 1AU. Photospheric magnetic field data is used as the inner boundary condition.The simulation results are summarized as: (1) The variation of solar wind speed is well controlled by the structure of magnetic fields at and little above the solar surface and (2) Far above the solar surface, the interface between high and low speed flows evolves to a structure suggestive of CIRs. Comparing the data from simulation with the actual solar wind data obtained by spacecrafts, we will discuss the future

  10. Comparison of plasma sheet ion composition with the IMF and solar wind plasma

    Science.gov (United States)

    Lennartsson, W.

    Plasma sheet energetic ion data (0.1- to 16 keV/e) obtained by the Plasma Composition Experiment on ISEE-1 between 10 and 23 earth radii are compared with concurrent IMF and solar wind plasma data. The densities of H(+) and He(++) ions in the plasma sheet are found to be the highest, and the most nearly proportional to the solar wind density, when the IMF B(z) is not northward. The density of terrestrial O(+) ions increases strongly with increasing magnitude of the IMF, in apparent agreement with the notion that the IMF plays a fundamental role in the electric coupling between the solar wind and the ionosphere.

  11. Determining the solar wind speed above active regions using remote radio-wave observations.

    Science.gov (United States)

    Bougeret, J L; Fainberg, J; Stone, R G

    1983-11-04

    A new technique has made it possible to measure the velocity of portions of the solar wind during its flow outward from the sun. This analysis utilizes spacecraft (ISEE-3) observations of radio emission generated in regions of the solar wind associated with solar active regions. By tracking the source of these radio waves over periods of days, it is possible to measure the motion of the emission regions. Evidence of solar wind acceleration during this outward flow, consistent with theoretical models, has also been obtained.

  12. The Hunt for the Missing Modes: Revealing the True Nature of the Solar Wind

    Science.gov (United States)

    2015-01-29

    AFRL-AFOSR-UK-TR-2015-0003 The Hunt for the Missing Modes: Revealing the True Nature of the Solar Wind James McLaughlin Northumbria University...To) 15 March 2013 – 31 August 2014 4. TITLE AND SUBTITLE The Hunt for the Missing Modes: Revealing the True Nature of the Solar Wind 5a. CONTRACT...for fast solar wind acceleration in the open-field corona. The development of this robust, versatile wave-tracking image-processing algorithm can

  13. Pioneer and Voyager observations of the solar wind at large heliocentric distances and latitudes

    Science.gov (United States)

    Gazis, P. R.; Mihalov, J. D.; Barnes, A.; Lazarus, A. J.; Smith, E. J.

    1989-01-01

    Data obtained from the electrostatic analyzers aboard the Pioneer 10 and 11 spacecraft and from the Faraday cup aboard Voyager 2 were used to study spatial gradients in the distant solar wind. Prior to mid-1985, both spacecraft observed nearly identical solar wind structures. After day 150 of 1985, the velocity structure at Voyager 2 became flatter, and the Voyager 2 velocities were smaller than those observed by Pioneer 11. It is suggested that these changes in the solar wind at low latitudes may be related to a change which occurred in the coronal hole structure in early 1985.

  14. Extremely high reflection of solar wind protons as neutral hydrogen atoms from regolith in space

    CERN Document Server

    Wieser, Martin; Futaana, Yoshifumi; Holmström, Mats; Bhardwaj, Anil; Sridharan, R; Dhanya, MB; Wurz, Peter; Schaufelberger, Audrey; Asamura, Kazushi; 10.1016/j.pss.2009.09.012

    2010-01-01

    We report on measurements of extremely high reflection rates of solar wind particles from regolith-covered lunar surfaces. Measurements by the Sub-keV Atom Reflecting Analyzer (SARA) instrument on the Indian Chandrayaan-1 spacecraft in orbit around the Moon show that up to 20% of the impinging solar wind protons are reflected from the lunar surface back to space as neutral hydrogen atoms. This finding, generally applicable to regolith-covered atmosphereless bodies, invalidates the widely accepted assumption that regolith almost completely absorbs the impinging solar wind.

  15. On the Interpretation of Magnetic Helicity Signatures in the Dissipation Range of Solar Wind Turbulence

    CERN Document Server

    Howes, Gregory G

    2009-01-01

    Measurements of small-scale turbulent fluctuations in the solar wind find a non-zero right-handed magnetic helicity. This has been interpreted as evidence for ion cyclotron damping. However, theoretical and empirical evidence suggests that the majority of the energy in solar wind turbulence resides in low frequency anisotropic kinetic Alfven wave fluctuations that are not subject to ion cyclotron damping. We demonstrate that a dissipation range comprised of kinetic Alfven waves also produces a net right-handed fluctuating magnetic helicity signature consistent with observations. Thus, the observed magnetic helicity signature does not necessarily imply that ion cyclotron damping is energetically important in the solar wind.

  16. On Lunar Exospheric Column Densities and Solar Wind Access Beyond the Terminator from ROSAT Soft X-Ray Observations of Solar Wind Charge Exchange

    Science.gov (United States)

    Collier, Michael R.; Snowden, S. L.; Sarantos, M.; Benna, M.; Carter, J. A.; Cravens, T. E.; Farrell, W. M.; Fatemi, S.; Hills, H. Kent; Hodges, R. R.; Holmstrom, M.; Kuntz, K. D.; Porter, F. Scott; Read, A.; Robertson, I. P.; Sembay, S. F.; Sibeck, D. G.; Stubbs, T. J.; Travnicek, P.; Walsh, B. M.

    2014-01-01

    We analyze the Rontgen satellite (ROSAT) position sensitive proportional counter soft X-ray image of the Moon taken on 29 June 1990 by examining the radial profile of the surface brightness in three wedges: two 19 deg wedges (one north and one south) 13-32 deg off the terminator toward the dark side and one wedge 38 deg wide centered on the antisolar direction. The radial profiles of both the north and the south wedges show significant limb brightening that is absent in the 38 deg wide antisolar wedge. An analysis of the soft X-ray intensity increase associated with the limb brightening shows that its magnitude is consistent with that expected due to solar wind charge exchange (SWCX) with the tenuous lunar atmosphere based on lunar exospheric models and hybrid simulation results of solar wind access beyond the terminator. Soft X-ray imaging thus can independently infer the total lunar limb column density including all species, a property that before now has not been measured, and provide a large-scale picture of the solar wind-lunar interaction. Because the SWCX signal appears to be dominated by exospheric species arising from solar wind implantation, this technique can also determine how the exosphere varies with solar wind conditions. Now, along with Mars, Venus, and Earth, the Moon represents another solar system body at which SWCX has been observed.

  17. Predicting the Reaction of the Magnetosphere-Ionosphere System to Driving by the Solar Wind: A Global Correlation Approach

    Science.gov (United States)

    Borovsky, J.; Denton, M.

    2016-12-01

    Using canonical correlation analysis (CCA) we are looking at the correlation patterns between the multi-variable solar-wind data set and an Earth data set of comprised of multiple measures of the state of the magnetosphere (geomagnetic indices and other indices). We will treat the Earth data set as a "stock market" and we define a "stock-market index". The primary correlation in the composite solar-wind-magnetosphere system yields a very accurate prediction of the reaction of the "index" to the solar wind, and the magnetosphere's reaction shows a remarkable degree of linearity with solar-wind parameters. Secondary correlations in the composite solar-wind-magnetosphere system show different modes of reaction of the magnetosphere to the solar wind. The CCA methodology highlights a physics versus mathematics dilemma in discerning how the solar wind drives the magnetosphere.

  18. Solar wind-Magnetosphere-Ionosphere Coupling and Aurora at Jupiter and Saturn

    Science.gov (United States)

    Bunce, E. J.; Cowley, S. W. H.

    2015-10-01

    Solar wind-magnetosphere-ionosphere coupling is accomplished through the existence of largescale field-aligned currents which are generated in a source region and end in a sink region, and which transfer momentum (and energy) between the regions. Therefore, to move beyond a theoretical picture of how this works at Jupiter and Saturn we require in-situ measurements of these regions primarily in the form of magnetic field measurements, but importantly combined with in-situ plasma, plasma wave data, and remote auroral observations. Since the arrival of Cassini at Saturn in 2004 we have had many opportunities to sample the high-latitude magnetosphere and aurora and have learned a great deal about how this giant magnetosphere works. We also await the "proximal" orbit phase of Cassini where we will obtain information on the high-latitude magnetosphere very close to Saturn. In the case of Jupiter, we eagerly anticipate the first high-latitude observations from the Juno mission, due to arrive in the Jupiter system in 2016. The simultaneous observations from Cassini at Saturn in the final phase of the mission until 2017, and Juno at Jupiter during 2016/17, will be a first in planetary science, and we expect to learn a great deal about both planetary magnetospheres individually and by comparison. Here then, we will give an overview of what we have learned so far from Cassini at Saturn, and how it might apply to Juno at Jupiter. A principal "source" of the field-aligned currents is the planetary neutral atmosphere, that at Saturn imposes both sub-corotation (and is axi-symmetric to a first approximation), as well as an m=1 rotating twin-vortex perturbation of comparable magnitude. The Cassini data have revealed that there are two separate systems in the Northern and Southern hemispheres rotating with slowly-changing separate periods. These have been systematically studied, principally in the pre-equinox (2008) Cassini data on the nightside. The sub-corotation system of field

  19. Examining Periodic Solar Wind Density Structures Observed in the SECCHI Heliospheric Imagers

    CERN Document Server

    Viall, Nicholeen M; Vourlidas, Angelos; Howard, Russell; 10.1007/s11207-010-9633-1

    2010-01-01

    We present an analysis of small-scale, periodic, solar-wind density enhancements (length-scales as small as \\approx 1000 Mm) observed in images from the Heliospheric Imager (HI) aboard STEREO A. We discuss their possible relationship to periodic fluctuations of the proton density that have been identified at 1 AU using in-situ plasma measurements. Specifically, Viall, Kepko, and Spence (2008) examined 11 years of in-situ solar-wind density measurements at 1 AU and demonstrated that not only turbulent structures, but also non-turbulent periodic density structures exist in the solar wind with scale sizes of hundreds to one thousand Mm. In a subsequent paper, Viall, Spence, and Kasper (2009) analyzed the {\\alpha} to proton solar-wind abundance ratio measured during one such event of periodic density structures, demonstrating that the plasma behavior was highly suggestive that either temporally or spatially varying coronal source plasma created those density structures. Large periodic density structures observed ...

  20. Beam tracking strategies for studies of kinetic scales in the solar wind with THOR-CSW

    Science.gov (United States)

    De Keyser, Johan; Lavraud, Benoit; Neefs, Eddy; Berkenbosch, Sophie; Anciaux, Michel; Maggiolo, Romain

    2016-04-01

    Modern plasma spectrometers for monitoring the solar wind attempt to intelligently track the energy and direction of the solar wind beam in order to obtain solar wind velocity distributions more efficiently. Such beam tracking strategies offer some benefits, but also have their limitations and drawbacks. Benefits include an improved resolution and/or a faster velocity distribution function acquisition time. Limitations are due to instrument characteristics that tend to be optimized for a particular range of particle energies and arrival directions. A drawback is the risk to miss an important part of the velocity distribution or to lose track of the beam altogether. A comparison is presented of different beam tracking strategies under consideration for the THOR-CSW instrument in order to highlight a number of design decisions and their impact on the acquired velocity distributions. The gain offered by beam tracking in terms of increased time resolution turns out to be essential for studies of solar wind physics at kinetic scales.

  1. Earth's magnetosphere and outer radiation belt under sub-Alfvénic solar wind

    Science.gov (United States)

    Lugaz, Noé; Farrugia, Charles J.; Huang, Chia-Lin; Winslow, Reka M.; Spence, Harlan E.; Schwadron, Nathan A.

    2016-10-01

    The interaction between Earth's magnetic field and the solar wind results in the formation of a collisionless bow shock 60,000-100,000 km upstream of our planet, as long as the solar wind fast magnetosonic Mach (hereafter Mach) number exceeds unity. Here, we present one of those extremely rare instances, when the solar wind Mach number reached steady values hours on 17 January 2013. Simultaneous measurements by more than ten spacecraft in the near-Earth environment reveal the evanescence of the bow shock, the sunward motion of the magnetopause and the extremely rapid and intense loss of electrons in the outer radiation belt. This study allows us to directly observe the state of the inner magnetosphere, including the radiation belts during a type of solar wind-magnetosphere coupling which is unusual for planets in our solar system but may be common for close-in extrasolar planets.

  2. On capture and acceleration of heavy ions (a-particle) in high-speed solar wind

    Institute of Scientific and Technical Information of China (English)

    SONG; Liting(宋礼庭); XIAO; Chijie(肖池阶)

    2002-01-01

    The α-particles and other heavy ions, as well es a few protons are observed to be faster than the main part of protons by about the local Alfven speed in the high-speed solar wind. It is suggested that when the velocity of the solar wind is equal to the local Alfven velocity, another Iow-frequency kinetic Alfvan wave will be excitated, and trap ail the α-particles and a few protons, so these ions have a local Alfven velocity faster than the other parts of the solar wind. The undamping kinetic Alfven waves change into Iow-frequency Alfven solitons in the solar wind. This model can explain the observation and give the conditions of wave excitated and ions trapped.

  3. Little or no solar wind enters Venus' atmosphere at solar minimum.

    Science.gov (United States)

    Zhang, T L; Delva, M; Baumjohann, W; Auster, H-U; Carr, C; Russell, C T; Barabash, S; Balikhin, M; Kudela, K; Berghofer, G; Biernat, H K; Lammer, H; Lichtenegger, H; Magnes, W; Nakamura, R; Schwingenschuh, K; Volwerk, M; Vörös, Z; Zambelli, W; Fornacon, K-H; Glassmeier, K-H; Richter, I; Balogh, A; Schwarzl, H; Pope, S A; Shi, J K; Wang, C; Motschmann, U; Lebreton, J-P

    2007-11-29

    Venus has no significant internal magnetic field, which allows the solar wind to interact directly with its atmosphere. A field is induced in this interaction, which partially shields the atmosphere, but we have no knowledge of how effective that shield is at solar minimum. (Our current knowledge of the solar wind interaction with Venus is derived from measurements at solar maximum.) The bow shock is close to the planet, meaning that it is possible that some solar wind could be absorbed by the atmosphere and contribute to the evolution of the atmosphere. Here we report magnetic field measurements from the Venus Express spacecraft in the plasma environment surrounding Venus. The bow shock under low solar activity conditions seems to be in the position that would be expected from a complete deflection by a magnetized ionosphere. Therefore little solar wind enters the Venus ionosphere even at solar minimum.

  4. Solar wind and coronal structure near sunspot minimum - Pioneer and SMM observations from 1985-1987

    Science.gov (United States)

    Mihalov, J. D.; Barnes, A.; Hundhausen, A. J.; Smith, E. J.

    1990-01-01

    Changes in solar wind speed and magnetic polarity observed at the Pioneer spacecraft are discussed here in terms of the changing magnetic geometry implied by SMM coronagraph observations over the period 1985-1987. The pattern of recurrent solar wind streams, the long-term average speed, and the sector polarity of the interplanetary magnetic field all changed in a manner suggesting both a temporal variation, and a changing dependence on heliographic latitude. Coronal observations during this epoch show a systematic variation in coronal structure and the magnetic structure imposed on the expanding solar wind. These observations suggest interpretation of the solar wind speed variations in terms of the familiar model where the speed increases with distance from a nearly flat interplanetary current sheet, and where this current sheet becomes aligned with the solar equatorial plane as sunspot minimum approaches, but deviates rapidly from that orientation after minimum.

  5. Low-dimensionality and predictability of solar wind and global magnetosphere during magnetic storms

    CERN Document Server

    Zivkovic, Tatjana

    2011-01-01

    The storm index SYM-H, the solar wind velocity v, and interplanetary magnetic field Bz show no signatures of low-dimensional dynamics in quiet periods, but tests for determinism in the time series indicate that SYM-H exhibits a significant low-dimensional component during storm time, suggesting that self-organization takes place during magnetic storms. Even though our analysis yields no discernible change in determinism during magnetic storms for the solar wind parameters, there are significant enhancement of the predictability and exponents measuring persistence. Thus, magnetic storms are typically preceded by an increase in the persistence of the solar wind dynamics, and this increase is also present in the magnetospheric response to the solar wind.

  6. Solar wind stream evolution at large heliocentric distances - Experimental demonstration and the test of a model

    Science.gov (United States)

    Gosling, J. T.; Hundhausen, A. J.; Bame, S. J.

    1976-01-01

    A stream propagation model which neglects all dissipation effects except those occurring at shock interfaces, was used to compare Pioneer-10 solar wind speed observations, during the time when Pioneer 10, the earth, and the sun were coaligned, with near-earth Imp-7 observations of the solar wind structure, and with the theoretical predictions of the solar wind structure at Pioneer 10 derived from the Imp-7 measurements, using the model. The comparison provides a graphic illustration of the phenomenon of stream steepening in the solar wind with the attendant formation of forward-reverse shock pairs and the gradual decay of stream amplitudes with increasing heliocentric distance. The comparison also provides a qualitative test of the stream propagation model.

  7. The Structure of the Solar Wind at Large Heliocentric Distances: CIRs and their Successors

    Science.gov (United States)

    Gazis, P. R.

    1999-01-01

    Co-rotating interaction regions (CIRs) and their associated shock pairs are dominant structures in the solar wind between the heliocentric distances of 2 and 8 AU. At larger heliocentric distances, these structures undergo a qualitative change. Shocks decay to a point where they are often difficult to detect, and may have little influence on the dynamics of the solar wind. Interaction regions spread and merge, though they appear to retain their identity to surprisingly large distances from the Sun. Solar wind and IMF data from the Pioneer 10, Pioneer 11, and Voyager 2 spacecraft were used to conduct a comprehensive survey of CIRs and their successors between heliocentric distances of 1 and 55 AU over the last two solar cycles. The structure of the solar wind varied in a consistent fashion with heliocentric distance. Similar structures were observed at similar heliocentric distances by all three spacecraft during different portions of the solar cycle.

  8. Large Storm Energy Deposition and Solar Wind Drivers: A Study of Geoeffectiveness

    Science.gov (United States)

    Turner, N. E.; Lopez, R. E.

    2004-12-01

    We examine the role of solar wind driving conditions in the deposition of large amounts of energy in the magnetosphere-ionosphere system. Our database consists of eight storms ranging in size, including especially the October and November 2003 superstorms. We estimate energy deposition into the ring current, ionospheric Joule heating, and auroral precipitation for each event and compare with relevant solar wind data. Results suggest that the magnetosonic Mach number of the solar wind may be a useful parameter in identifying the potential for large amounts of energy deposition, possibly because of the role of the bow shock in modulating the magnetosheath field, and therefore its influence of reconnection rates. We use Dst, ionospheric indices, and MHD simulation results where available to investigate the magnetospheric response to different types of solar wind energy input. Our results are examined with a focus on superstorms and the driving conditions observed in connection with them.

  9. Simulations of the Solar Wind Interaction with the Atmosphere/Ionosphere of Venus

    Science.gov (United States)

    Ledvina, Stephen; Brecht, Stephen H.; Bougher, Stephen W.

    2016-10-01

    The latest results of high resolution 3-D hybrid particle code simulations of the solar wind interacting with the atmosphere/ionosphere of Venus will be presented. The research is focused on understanding the how the solar wind interaction with Venus results in the subsequent ionospheric losses. In addition, the simulations focus on structures caused by the interaction particularly on the pole of the planet where the convection electric field points. A variety of simulation results will be presented each with varying solar wind parameters. The hybrid particle code HALFSHEL contains a variety of physical and chemical models which will also be discussed. These include a chemistry package that produces the ionosphere on grid resolution of 10 km altitude, atmospheric densities and dynamics from the VTGCM code and the Hall and Pedersen conductivities associated with plasma neutral collisions. The specific simulations to be presented trace solar wind protons, and ionospheric O+ and O2+.

  10. MESSENGER and Venus Express Observations of the Solar Wind Interaction with Venus

    Science.gov (United States)

    Slavin, James A.; Acuna, Mario H.; Anderson, Brian J.; Barabash, Stas; Benna, Mehdi; Boardsen, Scott A.; Fraenz, Markus; Gloeckler, George; Gold, Robert E.; Ho,George C.; Korth, Haje; Krimigis, Stamatios M.; McNutt, Ralph L., Jr.; Raines, Jim M.; Sarantos, Menelaos; Solomon, Sean C.; Zhang, Tielong; Zurbuchen, Thomas H.

    2009-01-01

    At 23:08 UTC on 5 June 2007 the MESSENGER spacecraft reached its closest approach altitude of 338 kin during its final flyby of Venus en route to its 2011 orbit insertion at Mercury. The availability of the simultaneous Venus Express solar wind and interplanetary magnetic field measurements provides a rare opportunity to examine the influence of upstream conditions on this planet's solar wind interaction. We present MESSENGER observations of new features of the Venus - solar wind interaction including hot flow anomalies upstream of the bow shock, a flux rope in the near-tail and a two-point determination of the timescale for magnetic flux transport through this induced magnetosphere. Citation: Stavin, J. A., et al. (2009), MESSENGER and Venus Express observations of the solar wind interaction with Venus,

  11. Estimates of Sputter Yields of Solar-Wind Heavy Ions of Lunar Regolith Materials

    Science.gov (United States)

    Barghouty, Abdulmasser F.; Adams, James H., Jr.

    2008-01-01

    At energies of approximately 1 keV/amu, solar-wind protons and heavy ions interact with the lunar surface materials via a number of microscopic interactions that include sputtering. Solar-wind induced sputtering is a main mechanism by which the composition of the topmost layers of the lunar surface can change, dynamically and preferentially. This work concentrates on sputtering induced by solar-wind heavy ions. Sputtering associated with slow (speeds the electrons speed in its first Bohr orbit) and highly charged ions are known to include both kinetic and potential sputtering. Potential sputtering enjoys some unique characteristics that makes it of special interest to lunar science and exploration. Unlike the yield from kinetic sputtering where simulation and approximation schemes exist, the yield from potential sputtering is not as easy to estimate. This work will present a preliminary numerical scheme designed to estimate potential sputtering yields from reactions relevant to this aspect of solar-wind lunar-surface coupling.

  12. Erosion of carbon/carbon by solar wind charged particle radiation during a solar probe mission

    Science.gov (United States)

    Sokolowski, Witold; O'Donnell, Tim; Millard, Jerry

    1991-01-01

    The possible erosion of a carbon/carbon thermal shield by solar wind-charged particle radiation is reviewed. The present knowledge of erosion data for carbon and/or graphite is surveyed, and an explanation of erosion mechanisms under different charged particle environments is discussed. The highest erosion is expected at four solar radii. Erosion rates are analytically estimated under several conservative assumptions for a normal quiet and worst case solar wind storm conditions. Mass loss analyses and comparison studies surprisingly indicate that the predicted erosion rate by solar wind could be greater than by nominal free sublimation during solar wind storm conditions at four solar radii. The predicted overall mass loss of a carbon/carbon shield material during the critical four solar radii flyby can still meet the mass loss mission requirement of less than 0.0025 g/sec.

  13. Polar solar wind and interstellar wind properties from interplanetary Lyman-alpha radiation measurements

    Science.gov (United States)

    Witt, N.; Blum, P. W.; Ajello, J. M.

    1981-01-01

    The analysis of Mariner 10 observations of Lyman-alpha resonance radiation shows an increase of interplanetary neutral hydrogen densities above the solar poles. This increase is caused by a latitudinal variation of the solar wind velocity and/or flux. Using both the Mariner 10 results and other solar wind observations, the values of the solar wind flux and velocity with latitude are determined for several cases of interest. The latitudinal variation of interplanetary hydrogen gas, arising from the solar wind latitudinal variation, is shown to be most pronounced in the inner solar system. From this result it is shown that spacecraft Lyman-alpha observations are more sensitive to the latitudinal anisotropy for a spacecraft location in the inner solar system near the downwind axis.

  14. Estimated solar wind-implanted helium-3 distribution on the Moon

    Science.gov (United States)

    Johnson, J. R.; Swindle, T.D.; Lucey, P.G.

    1999-01-01

    Among the solar wind-implanted volatiles present in the lunar regolith, 3 He is possibly the most valuable resource because of its potential as a fusion fuel. The abundance of 3 He in the lunar regolith at a given location depends on surface maturity, the amount of solar wind fluence, and titanium content, because ilmenite (FeTiO3) retains helium much better than other major lunar minerals. Surface maturity and TiO2 maps from Clementine multispectral data sets are combined here with a solar wind fluence model to produce a 3He abundance map of the Moon. Comparison of the predicted 3He values to landing site observations shows good correlation. The highest 3He abundances occur in the farside maria (due to greater solar wind fluence received) and in higher TiO2 nearside mare regions.

  15. Solar Wind Charge Exchange and O VIII emission toward MBM 12

    Science.gov (United States)

    Edgar, Richard J.; Wargelin, B. J.; Raymond, J. C.; Slavin, J. D.; Smith, R. K.; Kharchenko, V.

    2006-09-01

    A Chandra observation toward MBM-12, a nearby (MBM 12 during the Chandra observation. The Solar Wind Charge Exchange mechanism can account for essentially all of the O VIII emission seen in this observation.

  16. Solar wind heating by an embedded quasi-isothermal pick-up ion fluid

    Directory of Open Access Journals (Sweden)

    H. J. Fahr

    Full Text Available It is well known that the solar wind plasma consists of primary ions of solar coronal origin and secondary ions of interstellar origin. Interstellar H-atoms penetrate into the inner heliosphere and when ionized there are converted into secondary ions. These are implanted into the magnetized solar wind flow and are essentially enforced to co-move with this flow. By nonlinear interactions with wind-entrained Alfvén waves the latter are processed in the co-moving velocity space. This pick-up process, however, also causes actions back upon the original solar wind flow, leading to a deceleration, as well as a heating of the solar wind plasma. The resulting deceleration is not only due to the loading effect, but also due to the action of the pressure gradient. To calculate the latter, it is important to take into account the stochastic acceleration that suffers at their convection out of the inner heliosphere by the quasi-linear interactions with MHD turbulences. Only then can the presently reported VOYAGER observations of solar wind decelerations and heatings in the outer heliosphere be understood in terms of the current, most likely values of interstellar gas parameters. In a consistent view of the thermodynamics of the solar wind plasma, which is composed of secondary ions and solar wind protons, we also derive that the latter are globally heated at their motion to larger solar distances. The arising heat transfer is due to the action of suprathermal ions which drive MHD waves that are partially absorbed by solar wind protons and thereby establish their observed quasi-polytropy. We obtain a quantitative expression for the solar wind proton pressure as a function of solar distance. This expression clearly shows the change from an adiabatic to a quasi-polytropic behaviour with a decreasing polytropic index at increasing distances, as has been observed by the VOYAGERS. This also allows one to calculate the average percentage of the intitial energy

  17. Kinetic and Potential Sputtering Enhancements of Lunar Regolith Erosion: The Contribution of the Heavy Multicharged (Minority) Solar Wind Constituents

    Science.gov (United States)

    Meyer, F. W.; Barghouty, A. F.

    2012-01-01

    We report preliminary results for H+, Ar+1, Ar+6 and Ar+9 ion sputtering of JSC-1A lunar regolith simulant at solar wind velocities, obtain ed at the ORNL Multicharged Ion Research Facility using quadrupole ma ss spectrometry. The multi-charged Ar ions were used as proxies for i ntermediate mass solar wind multicharged ions. Prior to the Ar beam e xposures, the sample was exposed to high fluence H+ irradiation to si mulate H-loading due to the dominant solar wind constituent. A x80 en hancement of oxygen sputtering by Ar+ over same velocity H+ was measu red and an additional x2 increase for Ar+9 over same velocity Ar+ was demonstrated, giving clear evidence of the importance of potential s puttering by multicharged ions. This enhancement was observed to pers ist to the maximum fluences investigated (approx 10(exp 16)/sq cm). As discussed in a companion abstract by N. Barghouty, such persistent s puttering enhancement has significant implications on weathering and aging of lunar regolith. In addition, XPS measurements showed strong evidence of Fe reduction for those target areas that had been exposed to high fluence Ar+ and Ar+8 beams. Preferential oxidation of the Fe -reduced beam-exposed regions during transfer to the XPS system led t o enhanced O concentrations in those regions as well. On the basis of these very promising preliminary results, a NASA-LASER project on mo re extensive measurements was recently selected for funding. The prop osal expands the collaboration with NASA-MSFC for the simulation effort, and adds a new collaboration with NASA-GSFC for lunar mission-rele vant measurements.

  18. Cascade and Dissipation of Solar Wind Turbulence at Electron Scales: Whistlers or Kinetic Alfv\\'en Waves?

    Science.gov (United States)

    Sahraoui, Fouad; Goldstein, Melvyn L.

    2010-01-01

    Over the past few decades, large-scales solar wind (SW) turbulence has been studied extensively, both theoretically and observationally. Observed power spectra of the low frequency turbulence, which can be described in the magnetohydrodynamic (MHD) limit, are shown to obey the Kolmogorov scaling, $k"{ -5/3 }$, down the local proton gyrofrequency ($C{ci} \\sim O.l$-Hz). Turbulence at frequencies above $C{ci}$ has not been thoroughly investigated and remains far less well understood. Above $C{ ci}$ the spectrum steepens to $\\sim f"{ -2.5}$ and a debate exists as to whether the turbulence has become dominated by dispersive kinetic Alfven waves (KA W) or by whistler waves, before it is dissipated at small scales, In a case study Sahraoui et al., PRL (2009) have reported the first direct determination of the dissipation range of solar wind turbulence near the electron gyroscale using the high resolution Cluster magnetic and electric field data (up to $10"2$-Hz in the spacecraft reference frame). Above the Doppler-shifted proton scale $C{\\rho i}$ a new inertial range with a scaling $\\sim f"{ -2.3}$ has been evidenced and shown to remarkably agree with theoretical predictions of a quasi-two-dimensional cascade into KA W turbulence. Here, we use a wider sample of data sets of small scale SW turbulence under different plasma conditions, and investigate under which physical criteria the KA W (or the whistler) turbulence may be observed to carry out the cascade at small scales, These new observations/criteria are compared to the predictions on the cascade and the (kinetic) dissipation from the Vlasov theory. Implications of the results on the heating problem of the solar wind will be discussed.

  19. Effects of Solar Wind Conditions on the Plasma Wake Within a Polar Crater: Preliminary Results

    Science.gov (United States)

    Zimmerman, M. I.; Farrell, W. M.; Stubbs, T. J.

    2011-01-01

    As the solar wind sweeps horizontally past a shadowed lunar crater it simultaneously diffuses toward the surface through an ambipolar process, forming a plasma wake (e.g., Figure 1). Importantly, the resulting electric field structure diverts solar wind protons toward the cold crater floor where they may represent a source of surficial hydrogen. We present a handful of two-dimensional kinetic simulations exploring the range of wake structures and surface particle fluxes possible under various background plasma conditions.

  20. Kinetic scale turbulence and dissipation in the solar wind: key observational results and future outlook

    OpenAIRE

    2015-01-01

    Turbulence is ubiquitous in the solar wind. Turbulence causes kinetic and magnetic energy to cascade to small scales where they are eventually dissipated, adding heat to the plasma. The details of how this occurs are not well understood. This article reviews the evidence for turbulent dissipation and examines various diagnostics for identifying solar wind regions where dissipation is occurring. We also discuss how future missions will further enhance our understanding of the importance of tur...

  1. Three-fluid, three-dimensional magnetohydrodynamic solar wind model with eddy viscosity and turbulent resistivity

    Energy Technology Data Exchange (ETDEWEB)

    Usmanov, Arcadi V.; Matthaeus, William H. [Department of Physics and Astronomy, University of Delaware, Newark, DE 19716 (United States); Goldstein, Melvyn L., E-mail: arcadi.usmanov@nasa.gov [Code 672, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

    2014-06-10

    We have developed a three-fluid, three-dimensional magnetohydrodynamic solar wind model that incorporates turbulence transport, eddy viscosity, turbulent resistivity, and turbulent heating. The solar wind plasma is described as a system of co-moving solar wind protons, electrons, and interstellar pickup protons, with separate energy equations for each species. Numerical steady-state solutions of Reynolds-averaged solar wind equations coupled with turbulence transport equations for turbulence energy, cross helicity, and correlation length are obtained by the time relaxation method in the corotating with the Sun frame of reference in the region from 0.3 to 100 AU (but still inside the termination shock). The model equations include the effects of electron heat conduction, Coulomb collisions, photoionization of interstellar hydrogen atoms and their charge exchange with the solar wind protons, turbulence energy generation by pickup protons, and turbulent heating of solar wind protons and electrons. The turbulence transport model is based on the Reynolds decomposition and turbulence phenomenologies that describe the conversion of fluctuation energy into heat due to a turbulent cascade. In addition to using separate energy equations for the solar wind protons and electrons, a significant improvement over our previous work is that the turbulence model now uses an eddy viscosity approximation for the Reynolds stress tensor and the mean turbulent electric field. The approximation allows the turbulence model to account for driving of turbulence by large-scale velocity gradients. Using either a dipole approximation for the solar magnetic field or synoptic solar magnetograms from the Wilcox Solar Observatory for assigning boundary conditions at the coronal base, we apply the model to study the global structure of the solar wind and its three-dimensional properties, including embedded turbulence, heating, and acceleration throughout the heliosphere. The model results are

  2. Solar wind conditions leading to efficient radiation belt electron acceleration: A superposed epoch analysis

    OpenAIRE

    Li, W; Thorne, RM; Bortnik, J.; Baker, DN; Reeves, GD; Kanekal, SG; Spence, HE; Green, JC

    2015-01-01

    ©2015. American Geophysical Union. All Rights Reserved. Determining preferential solar wind conditions leading to efficient radiation belt electron acceleration is crucial for predicting radiation belt electron dynamics. Using Van Allen Probes electron observations ( > 1 MeV) from 2012 to 2015, we identify a number of efficient and inefficient acceleration events separately to perform a superposed epoch analysis of the corresponding solar wind parameters and geomagnetic indices. By directly c...

  3. Collisional Thermalization of Hydrogen and Helium in Solar Wind Plasma

    CERN Document Server

    Maruca, Bennett A; Sorriso-Valvo, Luca; Kasper, Justin C; Stevens, Michael L

    2013-01-01

    In situ observations of the solar wind frequently show the temperature of $\\alpha$-particles (fully ionized helium), $T_\\alpha$, to significantly differ from that of protons (ionized hydrogen), $T_p$. Many heating processes in the plasma act preferentially on $\\alpha$-particles, even as collisions among ions act to gradually establish thermal equilibrium. Measurements from the $\\textit{Wind}$ spacecraft's Faraday cups reveal that, at $r=1.0\\ \\textrm{AU}$ from the Sun, the observed values of the $\\alpha$-proton temperature ratio, $\\theta_{\\alpha p} \\equiv T_\\alpha\\,/\\,T_p$ has a complex, bimodal distribution. This study applied a simple model for the radial evolution of $\\theta_{\\alpha p}$ to these data to compute expected values of $\\theta_{\\alpha p}$ at $r=0.1\\ \\textrm{AU}$. These inferred $\\theta_{\\alpha p}$-values have no trace of the bimodality seen in the $\\theta_{\\alpha p}$-values measured at $r=1.0\\ \\textrm{AU}$ but are instead consistent with the actions of the known mechanisms for $\\alpha$-particle p...

  4. Solar coronal plumes and the fast solar wind

    CERN Document Server

    Dwivedi, B N

    2015-01-01

    The spectral profiles of the coronal Ne viii line at 77 nm have different shapes in quiet-Sun regions and coronal holes (CHs). A single Gaussian fit of the line profile provides an adequate approximation in quiet-Sun areas, whereas a strong shoulder on the long-wavelength side is a systematic feature in CHs. Although this has been noticed since 1999, no physical reason for the peculiar shape could be given. In an attempt to identify the cause of this peculiarity, we address three problems that could not be conclusively resolved in a review article by a study team of the International Space Science Institute (ISSI; Wilhelm et al. 2011) : (1) The physical processes operating at the base and inside of plumes as well as their interaction with the solar wind (SW). (2) The possible contribution of plume plasma to the fast SW streams. (3) The signature of the first-ionization potential (FIP) effect between plumes and inter-plume regions (IPRs). Before the spectroscopic peculiarities in IPRs and plumes in polar coron...

  5. Implications of the Deep Minimum for Slow Solar Wind Origin

    Science.gov (United States)

    Antiochos, S. K.; Mikic, Z.; Lionello, R.; Titov, V. S.; Linker, J. A.

    2009-12-01

    The origin of the slow solar wind has long been one of the most important problems in solar/heliospheric physics. Two observational constraints make this problem especially challenging. First, the slow wind has the composition of the closed-field corona, unlike the fast wind that originates on open field lines. Second, the slow wind has substantial angular extent, of order 30 degrees, which is much larger than the widths observed for streamer stalks or the widths expected theoretically for a dynamic heliospheric current sheet. We propose that the slow wind originates from an intricate network of narrow (possibly singular) open-field corridors that emanate from the polar coronal hole regions. Using topological arguments, we show that these corridors must be ubiquitous in the solar corona. The total solar eclipse in August 2008, near the lowest point of the Deep Minimum, affords an ideal opportunity to test this theory by using the ultra-high resolution Predictive Science's (PSI) eclipse model for the corona and wind. Analysis of the PSI eclipse model demonstrates that the extent and scales of the open-field corridors can account for both the angular width of the slow wind and its closed-field composition. We discuss the implications of our slow wind theory for the structure of the corona and heliosphere at the Deep Minimum and describe further observational and theoretical tests. This work has been supported by the NASA HTP, SR&T, and LWS programs.

  6. Space Weather and Solar Wind Studies with OWFA

    Science.gov (United States)

    Manoharan, P. K.; Subrahmanya, C. R.; Chengalur, J. N.

    2017-03-01

    In this paper, we review the results of interplanetary scintillation (IPS) observations made with the legacy system of the Ooty Radio Telescope (ORT) and compare them with the possibilities opened by the upgraded ORT, the Ooty Wide Field Array (OWFA). The stability and the sensitivity of the legacy system of ORT allowed the regular monitoring of IPS on a grid of large number of radio sources and the results of these studies have been useful to understand the physical processes in the heliosphere and space weather events, such as coronal mass ejections, interaction regions and their propagation effects. In the case of OWFA, its wide bandwidth of 38 MHz, the large field-of-view of 27° and increased sensitivity provide a unique capability for the heliospheric science at 326.5 MHz. IPS observations with the OWFA would allow one to monitor more than 5000 sources per day. This, in turn, will lead to much improved studies of space weather events and solar wind plasma, overcoming the limitations faced with the legacy system. We also highlight some of the specific aspects of the OWFA, potentially relevant for the studies of coronal plasma and its turbulence characteristics.

  7. A Model for the Sources of the Slow Solar Wind

    CERN Document Server

    Antiochos, S K; Titov, V S; Lionello, R; Linker, J A

    2011-01-01

    Models for the origin of the slow solar wind must account for two seemingly contradictory observations: The slow wind has the composition of the closed field corona, implying that it originates from the continuous opening and closing of flux at the boundary between open and closed field. On the other hand, the slow wind also has large angular width, up to ~ 60{\\circ}, suggesting that its source extends far from the open-closed boundary. We propose a model that can explain both observations. The key idea is that the source of the slow wind at the Sun is a network of narrow (possibly singular) open-field corridors that map to a web of separatrices and quasi-separatrix layers in the heliosphere. We compute analytically the topology of an open-field corridor and show that it produces a quasi-separatrix layer in the heliosphere that extends to angles far from the heliospheric current sheet. We then use an MHD code and MDI/SOHO observations of the photospheric magnetic field to calculate numerically, with high spat...

  8. Decay of Solar Wind Turbulence behind Interplanetary Shocks

    Science.gov (United States)

    Pitňa, Alexander; Šafránková, Jana; Němeček, Zdeněk; Franci, Luca

    2017-07-01

    We investigate the decay of magnetic and kinetic energies behind IP shocks with motivation to find a relaxation time when downstream turbulence reaches a usual solar wind value. We start with a case study that introduces computation techniques and quantifies a contribution of kinetic fluctuations to the general energy balance. This part of the study is based on high-time (31 ms) resolution plasma data provided by the Spektr-R spacecraft. On the other hand, a statistical part is based on 92 s Wind plasma and magnetic data and its results confirm theoretically established decay laws for kinetic and magnetic energies. We observe the power-law behavior of the energy decay profiles and we estimated the power-law exponents of both kinetic and magnetic energy decay rates as -1.2. We found that the decay of MHD turbulence does not start immediately after the IP shock ramp and we suggest that the proper decay of turbulence begins when a contribution of the kinetic processes becomes negligible. We support this suggestion with a detailed analysis of the decay of turbulence at the kinetic scale.

  9. SCALING OF THE ELECTRON DISSIPATION RANGE OF SOLAR WIND TURBULENCE

    Energy Technology Data Exchange (ETDEWEB)

    Sahraoui, F.; Belmont, G.; Rétino, A.; Robert, P.; De Patoul, J. [Laboratoire de Physique des Plasmas, CNRS-Ecole Polytechnique-UPMC, Route de Saclay, F-92120 Palaiseau (France); Huang, S. Y. [School of Electronics and Information, Wuhan University, Wuhan (China); Goldstein, M. L., E-mail: fouad.sahraoui@lpp.polytechnique.fr [NASA Goddard Space Flight Center, Code 672, Greenbelt, MD 20771 (United States)

    2013-11-01

    Electron scale solar wind (SW) turbulence has attracted great interest in recent years. Considerable evidence exists that the turbulence is not fully dissipated near the proton scale, but continues cascading down to electron scales. However, the scaling of the magnetic energy spectra as well as the nature of the plasma modes involved at those small scales are still not fully determined. Here we survey 10 yr of the Cluster STAFF search-coil magnetometer waveforms measured in the SW and perform a statistical study of the magnetic energy spectra in the frequency range [1, 180] Hz. We found that 75% of the analyzed spectra exhibit breakpoints near the electron gyroscale ρ{sub e}, followed by steeper power-law-like spectra. We show that the scaling below the electron breakpoint cannot be determined unambiguously due to instrumental limitations that we discuss in detail. We compare our results to those reported in other studies and discuss their implications for the physical mechanisms involved and for theoretical modeling of energy dissipation in the SW.

  10. Scaling of the Electron Dissipation Range of Solar Wind Turbulence

    Science.gov (United States)

    Sahraoui, F.; Huang, S. Y.; Belmont, G.; Goldstein, M. L.; Rétino, A.; Robert, P.; De Patoul, J.

    2013-11-01

    Electron scale solar wind (SW) turbulence has attracted great interest in recent years. Considerable evidence exists that the turbulence is not fully dissipated near the proton scale, but continues cascading down to electron scales. However, the scaling of the magnetic energy spectra as well as the nature of the plasma modes involved at those small scales are still not fully determined. Here we survey 10 yr of the Cluster STAFF search-coil magnetometer waveforms measured in the SW and perform a statistical study of the magnetic energy spectra in the frequency range [1, 180] Hz. We found that 75% of the analyzed spectra exhibit breakpoints near the electron gyroscale ρ e , followed by steeper power-law-like spectra. We show that the scaling below the electron breakpoint cannot be determined unambiguously due to instrumental limitations that we discuss in detail. We compare our results to those reported in other studies and discuss their implications for the physical mechanisms involved and for theoretical modeling of energy dissipation in the SW.

  11. Plasma Beta Dependence of Magnetic Compressibility in Solar Wind Turbulence

    Science.gov (United States)

    Chapman, S. C.; Hnat, B.; Kiyani, K. H.; Sahraoui, F.

    2014-12-01

    The turbulent signature of MHD scales in the near-Earth solar wind are known to be primarily incompressible which manifests itself in magnetic field fluctuation vector components to be aligned primarily perpendicular to the background magnetic field -- so-called "Variance Anisotropy". This, and other facts, have been seen as evidence for a majority Alfvenic turbulence cascade; with a small component (10%) of compressible fluctuations. When one approaches scales on the order of the ion-inertial length and the Larmor radius, this behaviour changes and it is now becoming increasingly evident that the spectral break at these scales is also accompanied by an increase in magnetic compressibility. This has been attributed to a phase change in the physics at these scales -- from fluid to kinetic -- and in particular to the dominant role of the Hall-effect at sub-ion scales. We will be presenting results from the Cluster mission to show how this increase in the compressibility is dependent on the ion plasma beta and what implications this has for the physics at sub-ion scales in the context of prominent theories and models for kinetic plasma turbulence.

  12. Space Weather and Solar Wind Studies with OWFA

    Indian Academy of Sciences (India)

    P. K. Manoharan; C. R. Subrahmanya; J. N. Chengalur

    2017-03-01

    In this paper, we review the results of interplanetary scintillation (IPS) observations made with the legacy system of the Ooty Radio Telescope (ORT) and compare them with the possibilities opened by the upgraded ORT, the Ooty Wide Field Array (OWFA). The stability and the sensitivity of the legacy system of ORT allowed the regular monitoring of IPS on a grid of large number of radio sources and the results of these studies have been useful to understand the physical processes in the heliosphere and space weather events, such as coronal mass ejections, interaction regions and their propagation effects. In the case of OWFA, its wide bandwidth of 38 MHz, the large field-of-view of $\\sim$27$^\\circ$ and increased sensitivity provide a unique capability for the heliospheric science at 326.5 MHz. IPS observations with the OWFA would allow one to monitor more than 5000 sources per day. This, in turn, will lead to much improved studies of space weather events and solar wind plasma, overcoming the limitations faced with the legacy system. We also highlight some of the specific aspects of the OWFA, potentially relevant for the studies of coronal plasma and its turbulence characteristics.

  13. Solar wind and substorm excitation of the wavy current sheet

    Science.gov (United States)

    Forsyth, C.; Lester, M.; Fear, R. C.; Lucek, E.; Dandouras, I.; Fazakerley, A. N.; Singer, H.; Yeoman, T. K.

    2009-06-01

    Following a solar wind pressure pulse on 3 August 2001, GOES 8, GOES 10, Cluster and Polar observed dipolarizations of the magnetic field, accompanied by an eastward expansion of the aurora observed by IMAGE, indicating the occurrence of two substorms. Prior to the first substorm, the motion of the plasma sheet with respect to Cluster was in the ZGSM direction. Observations following the substorms show the occurrence of current sheet waves moving predominantly in the -YGSM direction. Following the second substorm, the current sheet waves caused multiple current sheet crossings of the Cluster spacecraft, previously studied by Zhang et al. (2002). We further this study to show that the velocity of the current sheet waves was similar to the expansion velocity of the substorm aurora and the expansion of the dipolarization regions in the magnetotail. Furthermore, we compare these results with the current sheet wave models of Golovchanskaya and Maltsev (2005) and Erkaev et al. (2008). We find that the Erkaev et al. (2008) model gives the best fit to the observations.

  14. Solar wind and substorm excitation of the wavy current sheet

    Directory of Open Access Journals (Sweden)

    C. Forsyth

    2009-06-01

    Full Text Available Following a solar wind pressure pulse on 3 August 2001, GOES 8, GOES 10, Cluster and Polar observed dipolarizations of the magnetic field, accompanied by an eastward expansion of the aurora observed by IMAGE, indicating the occurrence of two substorms. Prior to the first substorm, the motion of the plasma sheet with respect to Cluster was in the ZGSM direction. Observations following the substorms show the occurrence of current sheet waves moving predominantly in the −YGSM direction. Following the second substorm, the current sheet waves caused multiple current sheet crossings of the Cluster spacecraft, previously studied by Zhang et al. (2002. We further this study to show that the velocity of the current sheet waves was similar to the expansion velocity of the substorm aurora and the expansion of the dipolarization regions in the magnetotail. Furthermore, we compare these results with the current sheet wave models of Golovchanskaya and Maltsev (2005 and Erkaev et al. (2008. We find that the Erkaev et al. (2008 model gives the best fit to the observations.

  15. Solar energetic particle events in different types of solar wind

    Energy Technology Data Exchange (ETDEWEB)

    Kahler, S. W. [Air Force Research Laboratory, Space Vehicles Directorate, 3550 Aberdeen Avenue, Kirtland AFB, NM 87117 (United States); Vourlidas, A., E-mail: stephen.kahler@kirtland.af.mil [Space Sciences Division, Naval Research Laboratory, Washington, DC 20375 (United States)

    2014-08-10

    We examine statistically some properties of 96 20 MeV gradual solar energetic proton (SEP) events as a function of three different types of solar wind (SW) as classified by Richardson and Cane. Gradual SEP (E > 10 MeV) events are produced in shocks driven by fast (V ≳ 900 km s{sup –1}) and wide (W > 60°) coronal mass ejections (CMEs). We find no differences among the transient, fast, and slow SW streams for SEP 20 MeV proton event timescales. It has recently been found that the peak intensities Ip of these SEP events scale with the ∼2 MeV proton background intensities, which may be a proxy for the near-Sun shock seed particles. Both the intensities Ip and their 2 MeV backgrounds are significantly enhanced in transient SW compared to those of fast and slow SW streams, and the values of Ip normalized to the 2 MeV backgrounds only weakly correlate with CME V for all SW types. This result implies that forecasts of SEP events could be improved by monitoring both the Sun and the local SW stream properties and that the well known power-law size distributions of Ip may differ between transient and long-lived SW streams. We interpret an observed correlation between CME V and the 2 MeV background for SEP events in transient SW as a manifestation of enhanced solar activity.

  16. Some features of the small-scale solar wind fluctuations

    Science.gov (United States)

    Zastenker, G.; Eiges, P.; Avanov, L.; Astafyeva, N.; Zurbuchen, Th.; Bochsler, P.

    1995-06-01

    We have investigated small-scale variations of the solar wind ion flux measured with Faraday cups onboard the Prognoz-8 satellite. These measurements have a high time resolution of 1.24 seconds for intervals with a duration of several hours and as high as 0.02 seconds for some periods of about 1 hour duration. The main goal of this work is the determination of the quantitative features of fast ion flux fluctuations using mainly spectral analysis but also other methods. We also identify their association with interplanetary plasma parameters. Particularly, it is shown that the slope of the power spectra in the frequency range from 1E-4 to 6E-2 Hz is close to the classical Kolmogorov (-5/3) law. We also discuss some intervals with a very high level of the relative amplitude of flux fluctuations (10-20 percent) which were observed near the Earth's bow shock in the foreshock region. The use of the wavelet method for the long time series allows us to study the temporal evolution of power spectra.

  17. Slow Solar Wind: Observable Characteristics for Constraining Modelling

    Science.gov (United States)

    Ofman, L.; Abbo, L.; Antiochos, S. K.; Hansteen, V. H.; Harra, L.; Ko, Y. K.; Lapenta, G.; Li, B.; Riley, P.; Strachan, L.; von Steiger, R.; Wang, Y. M.

    2015-12-01

    The Slow Solar Wind (SSW) origin is an open issue in the post SOHO era and forms a major objective for planned future missions such as the Solar Orbiter and Solar Probe Plus.Results from spacecraft data, combined with theoretical modeling, have helped to investigate many aspects of the SSW. Fundamental physical properties of the coronal plasma have been derived from spectroscopic and imaging remote-sensing data and in-situ data, and these results have provided crucial insights for a deeper understanding of the origin and acceleration of the SSW.Advances models of the SSW in coronal streamers and other structures have been developed using 3D MHD and multi-fluid equations.Nevertheless, there are still debated questions such as:What are the source regions of SSW? What are their contributions to the SSW?Which is the role of the magnetic topology in corona for the origin, acceleration and energy deposition of SSW?Which are the possible acceleration and heating mechanisms for the SSW?The aim of this study is to present the insights on the SSW origin and formationarisen during the discussions at the International Space Science Institute (ISSI) by the Team entitled ''Slowsolar wind sources and acceleration mechanisms in the corona'' held in Bern (Switzerland) in March2014--2015. The attached figure will be presented to summarize the different hypotheses of the SSW formation.

  18. Standing shocks in the inner slow solar wind

    CERN Document Server

    Li, Bo; Li, Xing

    2011-01-01

    The slow solar wind, or at least a significant part of it, originates from the region bordering streamer helmets, where the flow tube geometry is distinct from flow tubes rooted in the center of coronal holes. We examine whether this particular tube geometry leads to standing shocks in the inner slow wind in this region. To isolate the influence of tube geometry, a simple isothermal wind model is employed and is solved in terms of the Lambert W function. In addition to a continuous solution, the model may also admit solutions with shocks, readily constructed with a graphical approach. When allowed, the shock solutions appear in pairs, one with a shock located in the streamer stalk, the other with a shock below the cusp along the streamer border. We show that solutions with standing shocks exist in a broad area in the parameter space characterizing the wind temperature and flow tube. In particular, streamers with cusps located at a heliocentric distance $\\gtrsim 3.2 R_\\odot$ can readily support discontinuous s...

  19. SOLAR WIND COLLISIONAL AGE FROM A GLOBAL MAGNETOHYDRODYNAMICS SIMULATION

    Energy Technology Data Exchange (ETDEWEB)

    Chhiber, R; Usmanov, AV; Matthaeus, WH [Department of Physics and Astronomy and Bartol Research Institute, University of Delaware, Newark, DE 19716 (United States); Goldstein, ML [NASA Goddard Space Flight Center, Greenbelt MD 20771 (United States)

    2016-04-10

    Simple estimates of the number of Coulomb collisions experienced by the interplanetary plasma to the point of observation, i.e., the “collisional age”, can be usefully employed in the study of non-thermal features of the solar wind. Usually these estimates are based on local plasma properties at the point of observation. Here we improve the method of estimation of the collisional age by employing solutions obtained from global three-dimensional magnetohydrodynamics simulations. This enables evaluation of the complete analytical expression for the collisional age without using approximations. The improved estimation of the collisional timescale is compared with turbulence and expansion timescales to assess the relative importance of collisions. The collisional age computed using the approximate formula employed in previous work is compared with the improved simulation-based calculations to examine the validity of the simplified formula. We also develop an analytical expression for the evaluation of the collisional age and we find good agreement between the numerical and analytical results. Finally, we briefly discuss the implications for an improved estimation of collisionality along spacecraft trajectories, including Solar Probe Plus.

  20. Thermospheric Response to Solar Wind Electric Field Fluctuations

    Science.gov (United States)

    Perlongo, N. J.; Ridley, A. J.

    2013-12-01

    The electron density of the thermosphere is of paramount importance for radio communications and drag on low altitude satellites, particularly during geomagnetic storms. Transient enhancements of ion velocities and subsequent density and temperature increases frequently occur as a result of storm-driven solar wind electric field fluctuations. Since the Earth's dipole magnetic field is tilted and offset from the center of the planet, significant asymmetries arise that alter the thermospheric response to energy input based upon the time of day of the disturbance. This study utilizes the Global Ionosphere-Thermosphere Model (GITM) to investigate this phenomenon by enhancing the convective electric field for one hour of the day in 22 different simulations. An additional baseline run was conducted with no IMF perturbation. Furthermore, four configurations of Earth's magnetic field were considered, Internal Geomagnetic Reference Field (IGRF), a perfect dipole, a dipole tilted by 10 degrees, and a tilted and offset dipole. These runs were conducted at equinox when the amount of sunlight falling on the different hemispheres is the same. Two additional runs were conducted at the solstices for comparison. It was found that the most geo-effective times are when the poles are pointed towards the sun. The electron density, neutral density and temperature as well as the winds are explored.

  1. Energy spectrum transfer equations of solar wind turbulence

    Science.gov (United States)

    Tu, C.-Y.

    1995-01-01

    The recent studies of transfer equations for solar wind magnetohydrodynamic (MHD) turbulence are reviewed with emphasis on the comparison with the statistical observational results. Helios and Voyager missions provide an opportunity to study the the radial evolution of the power spectrum. the cross-helicity the Alfven ratio and the minimum variance direction. Spectrum transfer equations are considered as a tool to explore the nature of this radial evolution of the fluctuations. The transfer equations are derived from incompressible MHD equations. Generally one needs to make assumptions about the nature of the fluctuations and the nature of the turbulent non-linear interactions to obtain numerical results which can be compared with the observations. Some special model results for several simple cases SUCH as for structures or strong mixing. for Alfven waves with weak turbulent interactions. and for a superposition of structures and Alfven waves. are discussed. The difference between the various approaches to derive and handle the transfer equations are also addressed. Finally some theoretical description of the compressible fluctuations are also briefly reviewed.

  2. A dynamical model of plasma turbulence in the solar wind.

    Science.gov (United States)

    Howes, G G

    2015-05-13

    A dynamical approach, rather than the usual statistical approach, is taken to explore the physical mechanisms underlying the nonlinear transfer of energy, the damping of the turbulent fluctuations, and the development of coherent structures in kinetic plasma turbulence. It is argued that the linear and nonlinear dynamics of Alfvén waves are responsible, at a very fundamental level, for some of the key qualitative features of plasma turbulence that distinguish it from hydrodynamic turbulence, including the anisotropic cascade of energy and the development of current sheets at small scales. The first dynamical model of kinetic turbulence in the weakly collisional solar wind plasma that combines self-consistently the physics of Alfvén waves with the development of small-scale current sheets is presented and its physical implications are discussed. This model leads to a simplified perspective on the nature of turbulence in a weakly collisional plasma: the nonlinear interactions responsible for the turbulent cascade of energy and the formation of current sheets are essentially fluid in nature, while the collisionless damping of the turbulent fluctuations and the energy injection by kinetic instabilities are essentially kinetic in nature.

  3. Dynamic properties of small-scale solar wind plasma fluctuations.

    Science.gov (United States)

    Riazantseva, M O; Budaev, V P; Zelenyi, L M; Zastenker, G N; Pavlos, G P; Safrankova, J; Nemecek, Z; Prech, L; Nemec, F

    2015-05-13

    The paper presents the latest results of the studies of small-scale fluctuations in a turbulent flow of solar wind (SW) using measurements with extremely high temporal resolution (up to 0.03 s) of the bright monitor of SW (BMSW) plasma spectrometer operating on astrophysical SPECTR-R spacecraft at distances up to 350,000 km from the Earth. The spectra of SW ion flux fluctuations in the range of scales between 0.03 and 100 s are systematically analysed. The difference of slopes in low- and high-frequency parts of spectra and the frequency of the break point between these two characteristic slopes was analysed for different conditions in the SW. The statistical properties of the SW ion flux fluctuations were thoroughly analysed on scales less than 10 s. A high level of intermittency is demonstrated. The extended self-similarity of SW ion flux turbulent flow is constantly observed. The approximation of non-Gaussian probability distribution function of ion flux fluctuations by the Tsallis statistics shows the non-extensive character of SW fluctuations. Statistical characteristics of ion flux fluctuations are compared with the predictions of a log-Poisson model. The log-Poisson parametrization of the structure function scaling has shown that well-defined filament-like plasma structures are, as a rule, observed in the turbulent SW flows.

  4. Solar wind measurements near Mars and their implication in the Red Planet environment

    Science.gov (United States)

    Trotignon, J. G.; Grard, R.; Barabash, S.; Lundin, R.; Dubinin, E.

    1996-02-01

    The Phobos 2 spacecraft was operational around Mars for almost two months. From 29 January to 27 March 1989, the Martian bow shock was crossed at least 200 times and the upstream regions extensively probed. The solar wind density and velocity deduced from the a.c. electric-field measurements performed with the PWS plasma and wave experiment are compared with those of the ASPERA 3-D plasma composition experiment. A reasonably good agreement is found between the 12 min averages of the plasma density numbers derived from PWS and ASPERA (considering the poor precision of the instruments): they differ by at most a factor of four. The solar wind density is found to decrease when the flow speed increases, in agreement with the stream structure of the solar wind, which results from heliomagnetic latitude dependencies of solar wind parameters. The solar wind ram pressure, which is essential to study the solar wind-Mars interaction, is also estimated: the absence of a clear relationship between this dynamic pressure and the bow shock location is confirmed. The bow shock observations performed during very high solar activity do not support the hypothesis that Mars possesses a significant intrinsic magnetic field.

  5. Influence of the ambient solar wind flow on the propagation behavior of interplanetary CMEs

    CERN Document Server

    Temmer, Manuela; Möstl, Christian; Veronig, Astrid M; Vrsnak, Bojan; Odstrcil, Dusan

    2011-01-01

    We study three CME/ICME events (2008 June 1-6, 2009 February 13-18, 2010 April 3-5) tracked from Sun to 1 AU in remote-sensing observations of STEREO Heliospheric Imagers and in situ plasma and magnetic field measurements. We focus on the ICME propagation in IP space that is governed by two forces, the propelling Lorentz force and the drag force. We address the question at which heliospheric distance range the drag becomes dominant and the CME gets adjusted to the solar wind flow. To this aim we analyze speed differences between ICMEs and the ambient solar wind flow as function of distance. The evolution of the ambient solar wind flow is derived from ENLIL 3D MHD model runs using different solar wind models, namely Wang-Sheeley-Arge (WSA) and MHD-Around-A-Sphere (MAS). Comparing the measured CME kinematics with the solar wind models we find that the CME speed gets adjusted to the solar wind speed at very different heliospheric distances in the three events under study: from below 30 Rs, to beyond 1 AU, depend...

  6. On the electron temperature downstream of the solar wind termination shock

    Energy Technology Data Exchange (ETDEWEB)

    Chashei, I.V. [Lebedev Physical Institute, Moscow (Russian Federation); Fahr, H.J. [Bonn Univ. (Germany). Argelander Inst. fuer Astronomie

    2013-09-01

    In this paper we study the temperatures of electrons convected with the solar wind to large solar distances and finally transported over the solar wind termination shock. Nearly nothing, unless at high energies in the cosmic ray regime, is known about the thermodynamical behaviour of these distant electrons from in situ plasma observations. Hence it is tacitly assumed these electrons, due to their adiabatic behaviour and vanishing heat conduction or energization processes, have rapidly cooled off to very low temperatures once they eventually arrive at the solar wind termination shock (at about 100 AU). In this paper we show that such electrons, however, at their passage over the termination shock due to the shock-electric field action undergo an overadiabatic heating and therefore appear on the downstream side as a substantially heated plasma species. Looking quantitatively into this heating process we find that solar wind electrons achieve temperatures of the order of 2-4 x 10{sup 6} K downstream of the termination shock, depending on the upstream solar wind bulk velocity and the shock compression ratio. Hence these electrons therewith play an important dynamical role in structuring this shock and determining the downstream plasma flow properties. Furthermore, they present an additional ionization source for incoming neutral interstellar hydrogen and excite X-ray emission. They also behave similar to cosmic ray electrons and extend to some limited region upstream of the shock of the order of 0.1 AU by spatial diffusion and thereby also modify the upstream solar wind properties. (orig.)

  7. Hybrid Model of Inhomogeneous Solar Wind Plasma Heating by Alfven Wave Spectrum: Parametric Studies

    Science.gov (United States)

    Ofman, L.

    2010-01-01

    Observations of the solar wind plasma at 0.3 AU and beyond show that a turbulent spectrum of magnetic fluctuations is present. Remote sensing observations of the corona indicate that heavy ions are hotter than protons and their temperature is anisotropic (T(sub perpindicular / T(sub parallel) >> 1). We study the heating and the acceleration of multi-ion plasma in the solar wind by a turbulent spectrum of Alfvenic fluctuations using a 2-D hybrid numerical model. In the hybrid model the protons and heavy ions are treated kinetically as particles, while the electrons are included as neutralizing background fluid. This is the first two-dimensional hybrid parametric study of the solar wind plasma that includes an input turbulent wave spectrum guided by observation with inhomogeneous background density. We also investigate the effects of He++ ion beams in the inhomogeneous background plasma density on the heating of the solar wind plasma. The 2-D hybrid model treats parallel and oblique waves, together with cross-field inhomogeneity, self-consistently. We investigate the parametric dependence of the perpendicular heating, and the temperature anisotropy in the H+-He++ solar wind plasma. It was found that the scaling of the magnetic fluctuations power spectrum steepens in the higher-density regions, and the heating is channeled to these regions from the surrounding lower-density plasma due to wave refraction. The model parameters are applicable to the expected solar wind conditions at about 10 solar radii.

  8. Signatures of Slow Solar Wind Streams from Active Regions in the Inner Corona

    Science.gov (United States)

    Slemzin, V.; Harra, L.; Urnov, A.; Kuzin, S.; Goryaev, F.; Berghmans, D.

    2013-08-01

    The identification of solar-wind sources is an important question in solar physics. The existing solar-wind models ( e.g., the Wang-Sheeley-Arge model) provide the approximate locations of the solar wind sources based on magnetic field extrapolations. It has been suggested recently that plasma outflows observed at the edges of active regions may be a source of the slow solar wind. To explore this we analyze an isolated active region (AR) adjacent to small coronal hole (CH) in July/August 2009. On 1 August, Hinode/EUV Imaging Spectrometer observations showed two compact outflow regions in the corona. Coronal rays were observed above the active-region coronal hole (ARCH) region on the eastern limb on 31 July by STEREO-A/EUVI and at the western limb on 7 August by CORONAS- Photon/TESIS telescopes. In both cases the coronal rays were co-aligned with open magnetic-field lines given by the potential field source surface model, which expanded into the streamer. The solar-wind parameters measured by STEREO-B, ACE, Wind, and STEREO-A confirmed the identification of the ARCH as a source region of the slow solar wind. The results of the study support the suggestion that coronal rays can represent signatures of outflows from ARs propagating in the inner corona along open field lines into the heliosphere.

  9. Mars atmospheric losses induced by the solar wind: Comparison of observations with models

    Science.gov (United States)

    Vaisberg, Oleg

    2015-12-01

    With new results from Mars-Express on plasma environment of Mars and two new Mars satellites the study Martian atmospheric losses receives new attention. Paper summarizes experimental results concentrating on configuration of Martian magnetosphere and the measurements of planetary ion escape induced by the solar wind. Several plasma populations constituting solar wind induced mass loss have been identified and studied: pick-up ions in shocked solar wind flow and induced (accretion) tail, ions accelerated in the tail current sheet, and outflow of ionospheric ions. Measured ion flux values and calculations of the total escape rate including solar cycle variations are summarized. Several types of simulation of the solar wind with Mars are considered and results of representative models are given and compared with experimental results. These computer models allowed one to much better understand solar wind-Mars interaction. However, there is significant difference between total loss rates obtained from simulation and ones from measurements on the spacecraft. Both measurements and simulation provide significant flux values that are considered as an important factor of mass loss during cosmogonic time of the planet. The origin of each solar wind induced loss component and its contribution to total amount are discussed and compared with relevant computer models. Future progress in experiments and simulation is briefly discussed.

  10. Multi-fluid MHD study of the solar wind interaction with Pluto

    Science.gov (United States)

    Dong, C.; Ma, Y.; McComas, D. J.; Bhattacharjee, A.; Zirnstein, E.; Toth, G.; Luhmann, J. G.; Wang, L.

    2016-12-01

    The study of the solar wind interaction with Pluto's upper atmosphere has triggered a great of interest in recent years. The Solar Wind Around Pluto (SWAP) instrument onboard New Horizon (NH) spacecraft has provided a wealth of detailed and quantitative information about Pluto and its interaction with the tenuous solar wind out at 33 AU. The SWAP data reveals Pluto's unique interaction with the solar wind as a hybrid of comet-like and the Venus/Mars-like interactions. While SWAP data has provided many of the key results, a lot of details are still missing merely based on NH flyby observations. In order to further investigate the solar wind-Pluto interaction from a global point of view, we develop a 3-D multi-fluid MHD (MF-MHD) model. The MF-MHD model solves separate continuity, momentum and energy equations for each ion species. We adopt the 1-D modeled neutral atmosphere, which is based on NH observations, as the MF-MHD input. Photoionization, charge exchange and electron impact ionization are all included in the MF-MHD model. We will study the ion escape rate, and Pluto's magnetosphere and heavy ion tail structure. We will also do some data-model comparisons. This work has the potential to improve our understanding of present day Pluto's unique solar wind interaction and thus enhance the science returned from the NH mission.

  11. Hybrid Model of Inhomogeneous Solar Wind Plasma Heating by Alfven Wave Spectrum: Parametric Studies

    Science.gov (United States)

    Ofman, L.

    2010-01-01

    Observations of the solar wind plasma at 0.3 AU and beyond show that a turbulent spectrum of magnetic fluctuations is present. Remote sensing observations of the corona indicate that heavy ions are hotter than protons and their temperature is anisotropic (T(sub perpindicular / T(sub parallel) >> 1). We study the heating and the acceleration of multi-ion plasma in the solar wind by a turbulent spectrum of Alfvenic fluctuations using a 2-D hybrid numerical model. In the hybrid model the protons and heavy ions are treated kinetically as particles, while the electrons are included as neutralizing background fluid. This is the first two-dimensional hybrid parametric study of the solar wind plasma that includes an input turbulent wave spectrum guided by observation with inhomogeneous background density. We also investigate the effects of He++ ion beams in the inhomogeneous background plasma density on the heating of the solar wind plasma. The 2-D hybrid model treats parallel and oblique waves, together with cross-field inhomogeneity, self-consistently. We investigate the parametric dependence of the perpendicular heating, and the temperature anisotropy in the H+-He++ solar wind plasma. It was found that the scaling of the magnetic fluctuations power spectrum steepens in the higher-density regions, and the heating is channeled to these regions from the surrounding lower-density plasma due to wave refraction. The model parameters are applicable to the expected solar wind conditions at about 10 solar radii.

  12. Three-Fluid Magnetohydrodynamic Modeling of the Solar Wind in the Outer Heliosphere

    Science.gov (United States)

    Usmanov, Arcadi V.; Goldstein, Melvyn L.; Matthaeus, William H.

    2011-01-01

    We have developed a three-fluid, fully three-dimensional magnetohydrodynamic model of the solar wind plasma in the outer heliosphere as a co-moving system of solar wind protons, electrons, and interstellar pickup protons, with separate energy equations for each species. Our approach takes into account the effects of electron heat conduction and dissipation of Alfvenic turbulence on the spatial evolution of the solar wind plasma and interplanetary magnetic fields. The turbulence transport model is based on the Reynolds decomposition of physical variables into mean and fluctuating components and uses the turbulent phenomenologies that describe the conversion of fluctuation energy into heat due to a turbulent cascade. We solve the coupled set of the three-fluid equations for the mean-field solar wind and the turbulence equations for the turbulence energy, cross helicity, and correlation length. The equations are written in the rotating frame of reference and include heating by turbulent dissipation, energy transfer from interstellar pickup protons to solar wind protons, and solar wind deceleration due to the interaction with the interstellar hydrogen. The numerical solution is constructed by the time relaxation method in the region from 0.3 to 100 AU. Initial results from the novel model are presented.

  13. Plasma-field Coupling at Small Length Scales in Solar Wind Near 1 AU

    Science.gov (United States)

    Livadiotis, G.; Desai, M. I.

    2016-10-01

    In collisionless plasmas such as the solar wind, the coupling between plasma constituents and the embedded magnetic field occurs on various temporal and spatial scales, and is primarily responsible for the transfer of energy between waves and particles. Recently, it was shown that the transfer of energy between solar wind plasma particles and waves is governed by a new and unique relationship: the ratio between the magnetosonic energy and the plasma frequency is constant, E ms/ω pl ˜ ℏ*. This paper examines the variability and substantial departure of this ratio from ℏ* observed at ˜1 au, which is caused by a dispersion of fast magnetosonic (FMS) waves. In contrast to the efficiently transferred energy in the fast solar wind, the lower efficiency of the slow solar wind can be caused by this dispersion, whose relation and characteristics are derived and studied. In summary, we show that (i) the ratio E ms/ω pl transitions continuously from the slow to the fast solar wind, tending toward the constant ℏ* (ii) the transition is more efficient for larger thermal, Alfvén, or FMS speeds; (iii) the fast solar wind is almost dispersionless, characterized by quasi-constant values of the FMS speed, while the slow wind is subject to dispersion that is less effective for larger wind or magnetosonic speeds; and (iv) the constant ℏ* is estimated with the best known precision, ℏ* ≈ (1.160 ± 0.083) × 10-22 Js.

  14. Secondary electron emission from lunar soil by solar wind type ion impact: Laboratory measurements

    Science.gov (United States)

    Dukes, Catherine; Bu, Caixia; Baragiola, Raul A.

    2015-11-01

    Introduction: The lunar surface potential is determined by time-varying fluxes of electrons and ions from the solar wind, photoelectrons ejected by UV photons, cosmic rays, and micrometeorite impacts. Solar wind ions have a dual role in the charging process, adding positive charge to the lunar regolith upon impact and ejecting negative secondary electrons (SE). Electron emission occurs when the energy from the impacting ion is transferred to the solid, ionizing and damaging the material; electrons with kinetic energy greater than the ionization potential (band gap + electron affinity) are ejected from the solid[1].Experiment: We investigate the energy distribution of secondary electrons ejected from Apollo soils of varying maturity and lunar analogs by 4 keV He+. Soils are placed into a shallow Al cup and compressed. In-situ low-energy oxygen plasma is used to clean atmospheric contaminants from the soil before analysis[2]. X-ray photoelectron spectroscopy ascertains that the sample surface is clean. Experiments are conducted in a PHI 560 system (mirror electron energy analyzer (CMA) and μ-metal shield. The spectrometer is used to measure SE distributions, as well as for in situ surface characterization. A small negative bias (~5V) with respect to the grounded entrance grid of the CMA may be placed on the sample holder in order to expose the low energy cutoff.To measure SE energy distributions, primary ions rastered over a ~6 x 6 mm2 area are incident on the sample at ~40° relative to the surface normal, while SE emitted with an angle of 42.3°± 3.5° in a cone are analyzed.Results: The energy distribution of SE ejected from 4 keV He ion irradiation of albite with no bias applied shows positive charging of the surface. The general shape and distribution peak (~4 eV) are consistent with spectra for low energy ions on insulating material[1].Acknowledgements: We thank the NASA LASER program for support.References: [1]P. Riccardi, R. Baragiola et al. (2004); Surf

  15. Entry, Descent, and Landing Operations Analysis for the Genesis Entry Capsule

    Science.gov (United States)

    Desai, Prasun N.; Lyons, Daniel T.

    2007-01-01

    On September 8, 2004, the Genesis spacecraft returned to Earth after spending 29 months about the sun-Earth libration point (L1) collecting solar wind particles. Four hours prior to Earth arrival, the sample return capsule containing the samples was released for entry and subsequent landing at the Utah Test and Training Range. This paper provides an overview of the entry, descent, and landing trajectory analysis that was performed during the mission operations phase leading up to final approach to Earth. The final orbit determination solution produced an inertial entry flight-path angle of -8.002 deg (which was the desired nominal value) with a 3-sigma error of +/-0.0274 deg (a third of the requirement). The operations effort accurately delivered the entry capsule to the desired landing site. The final landing location was 8.3 km from the target, and was well within the allowable landing area. Overall, the Earth approach operation procedures worked well and there were no issues (logistically or performance based) that arose. As a result, the process of targeting a capsule from deep space and accurately landing it on Earth was successfully demonstrated.

  16. Polar ionospheric responses to solar wind IMF changes

    Directory of Open Access Journals (Sweden)

    Y. Zhang

    Full Text Available Auroral and airglow emissions over Eureka (89° CGM during the 1997-98 winter show striking variations in relation to solar wind IMF changes. The period January 19 to 22, 1998, was chosen for detailed study, as the IMF was particularly strong and variable. During most of the period, Bz was northward and polar arcs were observed. Several overpasses by DMSP satellites during the four day period provided a clear picture of the particle precipitation producing the polar arcs. The spectral character of these events indicated excitation by electrons of average energy 300 to 500 eV. Only occasionally were electrons of average energy up to ~1 keV observed and these appeared transitory from the ground optical data. It is noted that polar arcs appear after sudden changes in IMF By, suggesting IMF control over arc initiation. When By is positive there is arc motion from dawn to dusk, while By is negative the motion is consistently dusk to dawn. F-region (anti-sunward convections were monitored through the period from 630.0 nm emissions. The convection speed was low (100-150 m/s when Bz was northward but increased to 500 m/s after Bz turned southward on January 20.

    Key words: Atmospheric composition and structure (airglow and aurora - Ionosphere (particle precipitation - Magnetospheric Physics (polar cap phenomena

  17. Solar wind plasma interaction with solar probe plus spacecraft

    Energy Technology Data Exchange (ETDEWEB)

    Guillemant, S. [Univ. Paul Sabatier de Toulouse et CNRS, Toulouse (FR). IRAP (Inst. der Recherche en Astrophysique et Planetologie); ONERA (Office National d' Etudes et Recherches Aerospatiales), Toulouse (France); Genot, V.; Louarn, P. [Univ. Paul Sabatier de Toulouse et CNRS, Toulouse (FR). IRAP (Inst. der Recherche en Astrophysique et Planetologie); Mateo-Velez, J.C. [ONERA (Office National d' Etudes et Recherches Aerospatiales), Toulouse (France); Ergun, R. [Colorado Univ., Boulder, CO (United States). Lab. for Atmospheric and Space Physics

    2012-07-01

    3-D PIC (Particle In Cell) simulations of spacecraft-plasma interactions in the solar wind context of the Solar Probe Plus mission are presented. The SPIS software is used to simulate a simplified probe in the near-Sun environment (at a distance of 0.044AU or 9.5 R{sub S} from the Sun surface).We begin this study with a cross comparison of SPIS with another PIC code, aiming at providing the static potential structure surrounding a spacecraft in a high photoelectron environment. This paper presents then a sensitivity study using generic SPIS capabilities, investigating the role of some physical phenomena and numerical models. It confirms that in the near- sun environment, the Solar Probe Plus spacecraft would rather be negatively charged, despite the high yield of photoemission. This negative potential is explained through the dense sheath of photoelectrons and secondary electrons both emitted with low energies (2-3 eV). Due to this low energy of emission, these particles are not ejected at an infinite distance of the spacecraft and would rather surround it. As involved densities of photoelectrons can reach 10{sup 6} cm{sup -3} (compared to ambient ions and electrons densities of about 7 x 10{sup 3} cm{sup -3}), those populations affect the surrounding plasma potential generating potential barriers for low energy electrons, leading to high recollection. This charging could interfere with the low energy (up to a few tens of eV) plasma sensors and particle detectors, by biasing the particle distribution functions measured by the instruments. Moreover, if the spacecraft charges to large negative potentials, the problem will be more severe as low energy electrons will not be seen at all. The importance of the modelling requirements in terms of precise prediction of spacecraft potential is also discussed. (orig.)

  18. Perturbations of the solar wind flow by radial and latitudinal pick-up ion pressure gradients

    Directory of Open Access Journals (Sweden)

    H. J. Fahr

    2004-06-01

    Full Text Available It has been found that pick-up ions at their dynamical incorporation into the solar wind modify the original conditions of the asymptotic solar wind plasma flow. In this respect, it has meanwhile been revealed in many papers that these type of solar wind modifications, i.e. deceleration and decrease of effective Mach number, are not only due to the pick-up ion loading effects, but also to the action of pick-up ion pressure gradients. Up to now only the effects of radial pick-up ion pressure gradients were considered, however, analogously but latitudinal pressure gradients also appear to be important. Here we study the effects of radial and latitudinal pick-up ion pressure gradients, occurring especially during solar minimum conditions at mid-latitude regions where slow solar wind streams change to fast solar wind streams. First, we give estimates of the latitudinal wind components connected with these gradients, and then after revealing its importance, present a more quantitative calculation of solar wind velocity and density perturbations resulting from these pressure forces. It is shown that the relative density perturbations near and in the ecliptic increase with radial distance and thus may well explain the measured non-spherically symmetric density decrease with distance. We also show that the solar wind decelerations actually seen with Voyager-1/2 are in conciliation with interstellar hydrogen densities of nH∞≥0.1cm-3, in contrast to earlier claims for nH∞=0.05cm-3.

  19. The solar wind at solar maximum: comparisons of EISCAT IPS and in situ observations

    Directory of Open Access Journals (Sweden)

    A. R. Breen

    Full Text Available The solar maximum solar wind is highly structured in latitude, longitude and in time. Coronal measurements show a very high degree of variability, with large variations that are less apparent within in situ spacecraft measurements. Interplanetary scintillation (IPS observations from EISCAT, covering distances from 20 to 100 solar radii (RS, are an ideal source of information on the inner solar wind and can be used, therefore, to cast light on its evolution with distance from the Sun. Earlier comparisons of in situ and IPS measurements under solar minimum conditions showed good large-scale agreement, particularly in the fast wind. In this study we attempt a quantitative comparison of measurements made over solar maximum by EISCAT (20–100 RS and the Wind and Ulysses spacecraft (at 215 RS and 300–1000 RS, respectively. The intervals studied were August–September 1999, May 2000, September 2000 and May 2001, the last-named being the period of the second Ulysses fast latitude scan. Both ballistic and – when possible – MHD/ballistic hybrid models were used to relate the data sets, and we compare the results obtained from these two mapping methods. The results of this study suggest that solar wind velocities measured in situ were less variable than those estimated from IPS measurements closer to the Sun, with the greatest divergence between IPS velocities and in situ measurements occurring in regions where steep longitudinal velocity gradients were seen in situ. We suggest that the interaction between streams of solar wind with different velocities leads to "smoothing" of solar wind velocities between 30–60 RS and 1 AU, and that this process continues at greater distances from the Sun.

    Key words. Interplanetary physics (solar wind plasma; sources of the solar wind; instruments and techniques

  20. The plasma structure of coronal hole solar wind: Origins and evolution

    Science.gov (United States)

    Borovsky, Joseph E.

    2016-06-01

    Whereas slow solar wind is known to be highly structured, the fast (coronal hole origin) wind is usually considered to be homogeneous. Using measurements from Helios 1 + 2, ACE, Wind, and Ulysses, structure in the coronal hole origin solar wind is examined from 0.3 AU to 2.3 AU. Care is taken to collect and analyze intervals of "unperturbed coronal hole plasma." In these intervals, solar wind structure is seen in the proton number density, proton temperature, proton specific entropy, magnetic field strength, magnetic field to density ratio, electron heat flux, helium abundance, heavy-ion charge-state ratios, and Alfvenicity. Typical structure amplitudes are factors of 2, far from homogeneous. Variations are also seen in the solar wind radial velocity. Using estimates of the motion of the solar wind origin footpoint on the Sun for the various spacecraft, the satellite time series measurements are converted to distance along the photosphere. Typical variation scale lengths for the solar wind structure are several variations per supergranule. The structure amplitude and structure scale sizes do not evolve with distance from the Sun from 0.3 to 2.3 AU. An argument is quantified that these variations are the scale expected for solar wind production in open magnetic flux funnels in coronal holes. Additionally, a population of magnetic field foldings (switchbacks, reversals) in the coronal hole plasma is examined: this population evolves with distance from the Sun such that the magnetic field is mostly Parker spiral aligned at 0.3 AU and becomes more misaligned with distance outward.

  1. In-flight performance and preliminary observational results of Solar Wind Ion Detectors (SWIDs) on Chang'E-1

    Science.gov (United States)

    Kong, L. G.; Wang, S. J.; Wang, X. Y.; Zhang, A. B.; Zhu, G. W.; Yu, D. J.; Ren, Q. Y.; Reme, H.; Aoustin, C.; Zhang, X. G.; Feng, Y. B.; Zeng, L.

    2012-03-01

    SWIDs (Solar Wind Ion Detectors, SWID-A and SWID-B) are two of the scientific instruments on Chang'E-1, the first Chinese lunar mission. SWIDs utilize top-hat electrostatic analyzer to measure the low energy (alpha beam in solar wind. This is the first double ion beams event reported near the Moon. The double ion beams appeared having relatively anisotropic characteristics due to the interaction between solar wind and the Moon.

  2. Kinetic and Potential Sputtering of Lunar Regolith: The Contribution of the Heavy Highly Charged (Minority) Solar Wind Ions

    Science.gov (United States)

    Meyer, F. W.; Barghouty, A. F.

    2012-01-01

    Solar wind sputtering of the lunar surface helps determine the composition of the lunar exosphere and contributes to surface weathering. To date, only the effects of the two dominant solar wind constituents, H+ and He+, have been considered. The heavier, less abundant solar wind constituents have much larger sputtering yields because they have greater mass (kinetic sputtering) and they are highly charged (potential sputtering) Their contribution to total sputtering can therefore be orders of magnitude larger than their relative abundances would suggest

  3. Solar wind and other gases in the regoliths of the Pesyanoe parent object and the moon

    Science.gov (United States)

    Mathew, K. J.; Marti, K.

    2003-04-01

    We report new data from Pesyanoe-90,1 (dark lithology) on the isotopic signature of solar wind (SW) Xe as recorded in this enstatite achondrite which represents a soil-breccia of an asteroidal regolith. The low temperature (800 deg C) steps define the Pesyanoe-S xenon component, which is isotopically consistent with SW Xe reported for the lunar regolith. This implies that the SW Xe isotopic signature was the same at two distinct solar system locations and, importantly, also at different times of solar irradiation. Further, we compare the calculated average solar wind "SW-Xe" signature to Chass-S Xe, the indigenous Xe observed in SNC (Mars) meteorites. Again, a close agreement between these compositions is observed, which implies that a mass-dependent differential fractionation of Xe between SW-Xe and Chass-S Xe is document a fission component due to extinct 244Pu. Interestingly, the Pesyanoe-F Xe component is revealed only at the highest temperatures (>1200 deg C). The Pesyanoe-F gas reveals Xe isotopic signatures that are consistent with lunar solar energetic particles (SEP) data and may indicate a distinct solar energetic particle radiation as was inferred for the moon. However, we cannot rule out fractionation processes due to parent body processes. We note that ratios 36Ar/38Ar 5 are also consistent with SEP data. Calculated abundances of the fission component correlate well with radiogenic 40Ar concentrations, revealing rather constant 244Pu/K ratios in Pesyanoe, and separates thereof, and indicate that both components were retained. We identify a nitrogen component (15N = 44) of non-solar origin with an isotopic signature distinct from indigenous N (15N = -33). While large excesses at 128Xe and 129Xe are observed in the lunar regolith samples, these excesses in Pesyanoe are small. On the other hand, significant 126Xe isotopic excesses, comparable to relative excesses observed in lunar soils and breccias, are prominent in the intermediate temperature steps of

  4. Self-similar signature of the active solar corona within the inertial range of solar-wind turbulence.

    Science.gov (United States)

    Kiyani, K; Chapman, S C; Hnat, B; Nicol, R M

    2007-05-25

    We quantify the scaling of magnetic energy density in the inertial range of solar-wind turbulence seen in situ at 1 AU with respect to solar activity. At solar maximum, when the coronal magnetic field is dynamic and topologically complex, we find self-similar scaling in the solar wind, whereas at solar minimum, when the coronal fields are more ordered, we find multifractality. This quantifies the solar-wind signature that is of direct coronal origin and distinguishes it from that of local MHD turbulence, with quantitative implications for coronal heating of the solar wind.

  5. Improving the Discoverability and Availability of Sample Data and Imagery in NASA's Astromaterials Curation Digital Repository Using a New Common Architecture for Sample Databases

    Science.gov (United States)

    Todd, N. S.; Evans, C.

    2015-01-01

    The Astromaterials Acquisition and Curation Office at NASA's Johnson Space Center (JSC) is the designated facility for curating all of NASA's extraterrestrial samples. The suite of collections includes the lunar samples from the Apollo missions, cosmic dust particles falling into the Earth's atmosphere, meteorites collected in Antarctica, comet and interstellar dust particles from the Stardust mission, asteroid particles from the Japanese Hayabusa mission, and solar wind atoms collected during the Genesis mission. To support planetary science research on these samples, NASA's Astromaterials Curation Office hosts the Astromaterials Curation Digital Repository, which provides descriptions of the missions and collections, and critical information about each individual sample. Our office is implementing several informatics initiatives with the goal of better serving the planetary research community. One of these initiatives aims to increase the availability and discoverability of sample data and images through the use of a newly designed common architecture for Astromaterials Curation databases.

  6. Two-dimensional hybrid models of H+-He++ expanding solar wind plasma heating

    Science.gov (United States)

    Ofman, L.; Viñas, A. F.; Maneva, Y.

    2014-06-01

    Preferential heating and acceleration of the solar wind He++ ions compared to protons in fast solar wind streams have been known for decades, thanks to in situ spacecraft measurements at 0.29-5 AU. Turbulent magnetic field fluctuations with approximate power law spectra have been observed as well. However, the exact causes of these processes are still not known due to the lack of detailed information on the magnetic field fluctuations and ion velocity distributions in the acceleration region of the solar wind. Here the collisionless heating processes in expanding solar wind plasma are investigated using 2-D hybrid modeling with parameters appropriate to the heliocentric distance of 10 RS. In this study the ion dynamics is described kinetically, while electrons are treated as a background massless fluid in an expanding solar wind model. The source of free energy for the heating is introduced through an initial nonequilibrium state of the plasma with large He++ ion temperature anisotropy or with super-Alfvénic relative ion drift. We also employ an externally imposed spectrum of magnetic fluctuations in the frequency range below the proton gyroresonant frequency to heat the He++ ions. We investigate the effects of solar wind radial expansion by modeling several values of the expansion rate in a parametric study. We find that the preferential ion heating is attained in both nonexpanding and expanding solar wind models. Thus, the expansion has little effect on the preferential He++ ion heating by the processes considered here. Moreover, the expansion leads to faster evolution of the magnetosonic drift instability, reducing the drift velocity to lower values sooner, and the corresponding generation of the magnetic fluctuations that heat the ions, compared to the nonexpanding case. This is due to the reduction of the perpendicular particle velocities in the expanding (inflated) frame. For cases with little proton perpendicular heating, the solar wind expansion leads to

  7. Small is different: RPC observations of a small scale comet interacting with the solar wind

    Science.gov (United States)

    Nilsson, Hans; Burch, James L.; Carr, Christopher M.; Eriksson, Anders I.; Glassmeier, Karl-Heinz; Henri, Pierre; Rosetta Plasma Consortium Team

    2016-10-01

    Rosetta followed comet 67P from low activity at more than 3 AU heliocentric distance to peak activity at perihelion and then out again. We study the evolution of the dynamic plasma environment using data from the Rosetta Plasma Consortium (RPC). Observations of cometary plasma began in August 2014, at a distance of 100 km from the comet nucleus and at 3.6 AU from the Sun. As the comet approached the Sun, outgassing from the comet increased, as did the density of the cometary plasma. Measurements showed a highly heterogeneous cold ion environment, permeated by the solar wind. The solar wind was deflected due to the mass loading from newly added cometary plasma, with no discernible slowing down. The magnetic field magnitude increased significantly above the background level, and strong low frequency waves were observed in the magnetic field, a.k.a. the "singing comet". Electron temperatures were high, leading to a frequently strongly negative spacecraft potential. In mid to late April 2015 the solar wind started to disappear from the observation region. This was associated with a solar wind deflection reaching nearly 180°, indicating that mass loading became efficient enough to form a solar wind-free region. Accelerated water ions, moving mainly in the anti-sunward direction, kept being observed also after the solar wind disappearance. Plasma boundaries began to form and a collisionopause was tentatively identified in the ion and electron data. At the time around perihelion, a diamagnetic cavity was also observed, at a surprisingly large distance from the comet. In late 2016 the solar wind re-appeared at the location of Rosetta, allowing for studies of asymmetry of the comet ion environment with respect to perihelion. A nightside excursion allowed us to get a glimpse of the electrodynamics of the innermost part of the plasma tail. Most of these phenomena are dependent on the small-scale physics of comet 67P, since for most of the Rosetta mission the solar wind

  8. Modeling the Solar Wind at the Ulysses, Voyager, and New Horizons Spacecraft

    CERN Document Server

    Kim, T K; Zank, G P; Elliott, H A; McComas, D J

    2016-01-01

    The outer heliosphere is a dynamic region shaped largely by the interaction between the solar wind and the interstellar medium. While interplanetary magnetic field and plasma observations by the Voyager spacecraft have significantly improved our understanding of this vast region, modeling the outer heliosphere still remains a challenge. We simulate the three-dimensional, time-dependent solar wind flow from 1 to 80 astronomical units (AU), where the solar wind is assumed to be supersonic, using a two-fluid model in which protons and interstellar neutral hydrogen atoms are treated as separate fluids. We use 1-day averages of the solar wind parameters from the OMNI data set as inner boundary conditions to reproduce time-dependent effects in a simplified manner which involves interpolation in both space and time. Our model generally agrees with Ulysses data in the inner heliosphere and Voyager data in the outer heliosphere. Ultimately, we present the model solar wind parameters extracted along the trajectory of N...

  9. Validating a Time-Dependent Wave-Turbulence-Driven Model of the Solar Wind

    CERN Document Server

    Lionello, Roberto; Downs, Cooper; Linker, Jon A; Mikić, Zoran; Verdini, Andrea

    2014-01-01

    Although the mechanisms responsible for heating the Sun's corona and accelerating the solar wind are still being actively investigated, it is largely accepted that photospheric motions provide the energy source and that the magnetic field must play a key role in the process. \\citet{2010ApJ...708L.116V} presented a model for heating and accelerating the solar wind based on the turbulent dissipation of Alfv\\'en waves. We first use a time-dependent model of the solar wind to reproduce one of \\citeauthor{2010ApJ...708L.116V}'s solutions; then we extend its application to the case when the energy equation includes thermal conduction and radiation losses, and the upper chromosphere is part of the computational domain. Using this model, we explore parameter space and describe the characteristics of a fast-solar-wind solution. We discuss how this formulation may be applied to a 3D MHD model of the coron a and solar wind \\citep{2009ApJ...690..902L}.

  10. Information theoretical approach to discovering solar wind drivers of the outer radiation belt

    Science.gov (United States)

    Wing, Simon; Johnson, Jay R.; Camporeale, Enrico; Reeves, Geoffrey D.

    2016-10-01

    The solar wind-magnetosphere system is nonlinear. The solar wind drivers of geosynchronous electrons with energy range of 1.8-3.5 MeV are investigated using mutual information, conditional mutual information (CMI), and transfer entropy (TE). These information theoretical tools can establish linear and nonlinear relationships as well as information transfer. The information transfer from solar wind velocity (Vsw) to geosynchronous MeV electron flux (Je) peaks with a lag time of 2 days. As previously reported, Je is anticorrelated with solar wind density (nsw) with a lag of 1 day. However, this lag time and anticorrelation can be attributed at least partly to the Je(t + 2 days) correlation with Vsw(t) and nsw(t + 1 day) anticorrelation with Vsw(t). Analyses of solar wind driving of the magnetosphere need to consider the large lag times, up to 3 days, in the (Vsw, nsw) anticorrelation. Using CMI to remove the effects of Vsw, the response of Je to nsw is 30% smaller and has a lag time Je. Nonstationarity in the system dynamics is investigated using windowed TE. When the data are ordered according to transfer entropy value, it is possible to understand details of the triangle distribution that has been identified between Je(t + 2 days) versus Vsw(t).

  11. Electromagnetic waves near the proton cyclotron frequency in the solar wind

    Science.gov (United States)

    Jian, Lan; Alexander, Robert; Wicks, Robert; Stevens, Michael; Figueroa-Vinas, Adolfo; Russell, Christopher

    2015-04-01

    Strong narrow-band electromagnetic waves around the proton cyclotron frequency have been found sporadically in the solar wind throughout the inner heliosphere. They are nearly-circularly polarized and propagate close to the magnetic field. Electromagnetic waves near the proton cyclotron frequency can be ion cyclotron waves or magnetosonic waves. They can play an important role in modulating the solar wind ion distribution, and contribute to the heating and acceleration of solar wind. Since the waves are left-hand or right-hand polarized in the spacecraft frame with similar characteristics, they are probably due to Doppler shift of a same type of waves, or there could be a mixture of waves with intrinsically different polarizations. Through the assistance of audification, we have studied the long-lasting low frequency wave events in 2005 using high-cadence magnetic field data from the Wind mission. The Solar Wind Experiment team of the Wind mission has provided the temperature anisotropies for core protons, beam protons, and alpha particles, as well as the beam drift for selected cases. We conduct wave dispersion analysis using these ion moments to examine if these waves can be explained by ion cyclotron anisotropy instability or ion beam instability related to the solar wind inhomogeneities.

  12. A STATISTICAL STUDY OF THE SOLAR WIND TURBULENCE AT ION KINETIC SCALES USING THE K-FILTERING TECHNIQUE AND CLUSTER DATA

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, O. W.; Li, X.; Jeska, L., E-mail: o.wyn.roberts@gmail.com, E-mail: xxl@aber.ac.uk [Department of Physics, Aberystwyth University, Aberystwyth SY23 3BZ (United Kingdom)

    2015-03-20

    Plasma turbulence at ion kinetic scales in the solar wind is investigated using the multi-point magnetometer data from the Cluster spacecraft. By applying the k-filtering method, we are able to estimate the full three-dimensional power spectral density P(ω{sub sc}, k) at a certain spacecraft frequency ω{sub sc} in wavevector (k) space. By using the wavevector at the maximum power in P(ω{sub sc}, k) at each sampling frequency ω{sub sc} and the Doppler shifted frequency ω{sub pla} in the solar wind frame, the dispersion plot ω{sub pla} = ω{sub pla}(k) is found. Previous studies have been limited to very few intervals and have been hampered by large errors, which motivates a statistical study of 52 intervals of solar wind. We find that the turbulence is predominantly highly oblique to the magnetic field k >> k {sub ∥}, and propagates slowly in the plasma frame with most points having frequencies smaller than the proton gyrofrequency ω{sub pla} < Ω{sub p}. Weak agreement is found that turbulence at the ion kinetic scales consists of kinetic Alfvén waves and coherent structures advected with plasma bulk velocity plus some minor more compressible components. The results suggest that anti-sunward and sunward propagating magnetic fluctuations are of similar nature in both the fast and slow solar wind at ion kinetic scales. The fast wind has significantly more anti-sunward flux than sunward flux and the slow wind appears to be more balanced.

  13. Apparent temperature anisotropies due to wave activity in the solar wind

    Directory of Open Access Journals (Sweden)

    E. Marsch

    2011-05-01

    Full Text Available The fast solar wind is a collisionless plasma permeated by plasma waves on many different scales. A plasma wave represents the natural interplay between the periodic changes of the electromagnetic field and the associated coherent motions of the plasma particles. In this paper, a model velocity distribution function is derived for a plasma in a single, coherent, large-amplitude wave. This model allows one to study the kinetic effects of wave motions on particle distributions. They are by in-situ spacecraft measured by counting, over a certain sampling time, the particles coming from various directions and having different energies. We compare our results with the measurements by the Helios spacecraft, and thus find that by assuming high wave activity we are able to explain key observed features of the measured distributions within the framework of our model. We also address the recent discussions on nonresonant wave–particle interactions and apparent heating. The applied time-averaging procedure leads to an apparent ion temperature anisotropy which is connected but not identical to the intrinsic temperature of the underlying distribution function.

  14. Empirically modelled Pc3 activity based on solar wind parameters

    Directory of Open Access Journals (Sweden)

    T. Raita

    2010-09-01

    Full Text Available It is known that under certain solar wind (SW/interplanetary magnetic field (IMF conditions (e.g. high SW speed, low cone angle the occurrence of ground-level Pc3–4 pulsations is more likely. In this paper we demonstrate that in the event of anomalously low SW particle density, Pc3 activity is extremely low regardless of otherwise favourable SW speed and cone angle. We re-investigate the SW control of Pc3 pulsation activity through a statistical analysis and two empirical models with emphasis on the influence of SW density on Pc3 activity. We utilise SW and IMF measurements from the OMNI project and ground-based magnetometer measurements from the MM100 array to relate SW and IMF measurements to the occurrence of Pc3 activity. Multiple linear regression and artificial neural network models are used in iterative processes in order to identify sets of SW-based input parameters, which optimally reproduce a set of Pc3 activity data. The inclusion of SW density in the parameter set significantly improves the models. Not only the density itself, but other density related parameters, such as the dynamic pressure of the SW, or the standoff distance of the magnetopause work equally well in the model. The disappearance of Pc3s during low-density events can have at least four reasons according to the existing upstream wave theory: 1. Pausing the ion-cyclotron resonance that generates the upstream ultra low frequency waves in the absence of protons, 2. Weakening of the bow shock that implies less efficient reflection, 3. The SW becomes sub-Alfvénic and hence it is not able to sweep back the waves propagating upstream with the Alfvén-speed, and 4. The increase of the standoff distance of the magnetopause (and of the bow shock. Although the models cannot account for the lack of Pc3s during intervals when the SW density is extremely low, the resulting sets of optimal model inputs support the generation of mid latitude Pc3 activity predominantly through

  15. Distant (200-238 Rsub(e)) magnetotail lobe characteristics during quiet solar wind conditions

    Energy Technology Data Exchange (ETDEWEB)

    Tsurutani, B.T.; Burton, M.E.; Smith, E.J.; Jones, D.E.; Lepping, R.P.; Lazarus, A.J.

    1987-03-01

    The distance (X = 200-238 Rsub(e)) tail lobe average properties under quiet solar wind conditions have been determined using simultaneous ISEE-3 magnetic field and IMP-8 magnetic field and plasma observations. Under external solar wind pressures of Psub(ext) B/sup 2/8..pi.. + Nk(Tsub(e) + Tsub(i) <5x10/sup -10/ dynes cm/sup -2/, an average tail lobe field strength of 7.1 + - 1.2 nT and average plasma beta (8..pi.. nk T/B/sup 2/) of 0.3 are determined. It is concluded that under quiet solar wind conditions, the distant tail lobes are typically dominated by the magnetic field pressure.

  16. Frame Dependence of the Electric Field Spectrum of Solar Wind Turbulence

    CERN Document Server

    Chen, C H K; Salem, C; Mozer, F S

    2011-01-01

    We present the first survey of electric field data using the ARTEMIS spacecraft in the solar wind to study inertial range turbulence. We find that the average perpendicular spectral index of the electric field depends on the frame of measurement. In the spacecraft frame it is -5/3, which matches the magnetic field due to the large solar wind speed in Lorentz transformation. In the mean solar wind frame, the electric field is primarily due to the perpendicular velocity fluctuations and has a spectral index slightly shallower than -3/2, which is close to the scaling of the velocity. These results are an independent confirmation of the difference in scaling between the velocity and magnetic field, which is not currently well understood. The spectral index of the compressive fluctuations was also measured and found to be close to -5/3, indicating that they are not only passive to the velocity but may also interact nonlinearly with the magnetic field.

  17. Proton Heating in Solar Wind Compressible Turbulence with Collisions between Counter-propagating Waves

    CERN Document Server

    He, Jiansen; Marsch, Eckart; Chen, Christopher H K; Wang, Linghua; Pei, Zhongtian; Zhang, Lei; Salem, Chadi S; Bale, Stuart D

    2015-01-01

    Magnetohydronamic turbulence is believed to play a crucial role in heating the laboratorial, space, and astrophysical plasmas. However, the precise connection between the turbulent fluctuations and the particle kinetics has not yet been established. Here we present clear evidence of plasma turbulence heating based on diagnosed wave features and proton velocity distributions from solar wind measurements by the Wind spacecraft. For the first time, we can report the simultaneous observation of counter-propagating magnetohydrodynamic waves in the solar wind turbulence. Different from the traditional paradigm with counter-propagating Alfv\\'en waves, anti-sunward Alfv\\'en waves (AWs) are encountered by sunward slow magnetosonic waves (SMWs) in this new type of solar wind compressible turbulence. The counter-propagating AWs and SWs correspond respectively to the dominant and sub-dominant populations of the imbalanced Els\\"asser variables. Nonlinear interactions between the AWs and SMWs are inferred from the non-orth...

  18. Magnetic fluctuation power near proton temperature anisotropy instability thresholds in the solar wind

    CERN Document Server

    Bale, S D; Howes, G G; Quataert, E; Salem, C; Sundkvist, D

    2009-01-01

    The proton temperature anisotropy in the solar wind is known to be constrained by the theoretical thresholds for pressure anisotropy-driven instabilities. Here we use approximately 1 million independent measurements of gyroscale magnetic fluctuations in the solar wind to show for the first time that these fluctuations are enhanced along the temperature anisotropy thresholds of the mirror, proton oblique firehose, and ion cyclotron instabilities. In addition, the measured magnetic compressibility is enhanced at high plasma beta ($\\beta_\\parallel \\gtrsim 1$) along the mirror instability threshold but small elsewhere, consistent with expectations of the mirror mode. The power in this frequency (the 'dissipation') range is often considered to be driven by the solar wind turbulent cascade, an interpretation which should be qualified in light of the present results. In particular, we show that the short wavelength magnetic fluctuation power is a strong function of collisionality, which relaxes the temperature aniso...

  19. Study of the solar wind-magnetosphere coupling on different time scales

    CERN Document Server

    Badruddin,

    2013-01-01

    Solar wind-magnetosphere coupling, its causes and consequences have been studied for the last several decades. However, the assessment of continuously changing behaviour of the sun, plasma and field flows in the interplanetary space and their influence on geomagnetic activity is still a subject of intense research. Search for the best possible coupling function is also important for space weather prediction. We utilize four geomagnetic indices (ap, aa, AE and Dst) as parameters of geomagnetic activity level in the earth's magnetosphere. In addition to these indices, we utilize various solar wind plasma and field parameters for the corresponding periods. We analyse the geomagnetic activity and plasma/field parameters at yearly, half-yearly, 27-day, daily, 3-hourly, and hourly time resolutions. Regression analysis using geomagnetic and solar wind data of different time resolutions, over a continuous long period, and at different phases of solar activity (increasing including maximum/decreasing including minimum...

  20. Entropy generation at the multi-fluid MHD solar wind termination shock

    CERN Document Server

    Fahr, H -J

    2014-01-01

    In a series of earlier papers, we have developed expressions for ion and electron velocity distribution functions and theirvelocity moments at the passage over the solar wind termination shock. As we have shown there, with introduction of appropriate particle invariants and the use of Liouville`s theorem one can get explicit solutions for the resulting total downstream pressure adding up from partial pressure contributions of solar wind protons, solar wind electrons and pick-up protons. These expressions deliver in a first step the main contributions to the total plasma pressure in the downstream plasma flow and consistently determine the shock compression ratio. Here now we start out from these individual fluid pressures downstream of the shock and thereafter evaluate for the first time the shock-induced entropy production of the different fluids, when they are passing over the shock to the downstream side. As is shown here, the resulting ion entropy production substantially deviates from earlier calculation...

  1. Differential kinetic dynamics and heating of ions in the turbulent solar wind

    CERN Document Server

    Valentini, F; Stabile, S; Pezzi, O; Servidio, S; De Marco, R; Marcucci, F; Bruno, R; Lavraud, B; De Keyser, J; Consolini, G; Brienza, D; Sorriso-Valvo, L; Retinò, A; Vaivads, A; Salatti, M; Veltri, P

    2016-01-01

    The solar wind plasma is a fully ionized and turbulent gas ejected by the outer layers of the solar corona at very high speed, mainly composed by protons and electrons, with a small percentage of helium nuclei and a significantly lower abundance of heavier ions. Since particle collisions are practically negligible, the solar wind is typically not in a state of thermodynamic equilibrium. Such a complex system must be described through self-consistent and fully nonlinear models, taking into account its multi-species composition and turbulence. We use a kinetic hybrid Vlasov-Maxwell numerical code to reproduce the turbulent energy cascade down to ion kinetic scales, in typical conditions of the uncontaminated solar wind plasma, with the aim of exploring the differential kinetic dynamics of the dominant ion species, namely protons and alpha particles. We show that the response of different species to the fluctuating electromagnetic fields is different. In particular, a significant differential heating of alphas w...

  2. Plasma streams in the Hermean dayside magnetosphere: solar wind injection through the reconnection region

    CERN Document Server

    Varela, J; Moncuquet, M

    2016-01-01

    The aim of this research is to simulate the interaction of the solar wind with the magnetic field of Mercury and to study the particle fluxes between the magnetosheath and the planet surface. We simulate the magnetosphere structure using the open source MHD code PLUTO in spherical geometry with a multipolar expansion of the Hermean magnetic field (Anderson, B. J. et al, 2012). We perform two simulations with realistic solar wind parameters to study the properties of a plasma stream originated in the reconnection region between the interplanetary and the Hermean magnetic field. The plasma precipitates along the open magnetic field lines to the planet surface showing a fast expansion, rarefaction and cooling. The plasma stream is correlated with a flattening of the magnetic field observed by MESSENGER due to the adjacency of the reconnection region where the solar wind is injected to the inner magnetosphere.

  3. Full-Sun observations for identifying the source of the slow solar wind.

    Science.gov (United States)

    Brooks, David H; Ugarte-Urra, Ignacio; Warren, Harry P

    2015-01-06

    Fast (>700 km s(-1)) and slow (~400 km s(-1)) winds stream from the Sun, permeate the heliosphere and influence the near-Earth environment. While the fast wind is known to emanate primarily from polar coronal holes, the source of the slow wind remains unknown. Here we identify possible sites of origin using a slow solar wind source map of the entire Sun, which we construct from specially designed, full-disk observations from the Hinode satellite, and a magnetic field model. Our map provides a full-Sun observation that combines three key ingredients for identifying the sources: velocity, plasma composition and magnetic topology and shows them as solar wind composition plasma outflowing on open magnetic field lines. The area coverage of the identified sources is large enough that the sum of their mass contributions can explain a significant fraction of the mass loss rate of the solar wind.

  4. ROSAT Observations of Solar Wind Charge Exchange with the Lunar Exosphere

    Science.gov (United States)

    Collier, Michael R.; Snowden, S. L.; Benna, M.; Carter, J. A.; Cravens, T. E.; Hills, H. Kent; Hodges, R. R.; Kuntz, K. D.; Porter, F. Scott; Read, A.; Robertson, I. P.; Sembay, S. F.; Sibeck, D. G.; Stubbs, Timothy J.; Travnicek, P.

    2012-01-01

    We analyze the ROSAT PSPC soft X-ray image of the Moon taken on 29 June 1990 by examining the radial profile of the count rate in three wedges, two wedges (one north and one south) 13-32 degrees off (19 degrees wide) the terminator towards the dark side and one wedge 38 degrees wide centered on the anti-solar direction. The radial profiles of both the north and the south wedges show substantial limb brightening that is absent in the 38 degree wide antisolar wedge. An analysis of the count rate increase associated with the limb brightening shows that its magnitude is consistent with that expected due to solar wind charge exchange (SWCX) with the tenuous lunar atmosphere. Along with Mars, Venus, and Earth, the Moon represents another solar system body at which solar wind charge exchange has been observed. This technique can be used to explore the solar wind-lunar interaction.

  5. Solar wind entry into the high-latitude terrestrial magnetosphere during geomagnetically quiet times.

    Science.gov (United States)

    Shi, Q Q; Zong, Q-G; Fu, S Y; Dunlop, M W; Pu, Z Y; Parks, G K; Wei, Y; Li, W H; Zhang, H; Nowada, M; Wang, Y B; Sun, W J; Xiao, T; Reme, H; Carr, C; Fazakerley, A N; Lucek, E

    2013-01-01

    An understanding of the transport of solar wind plasma into and throughout the terrestrial magnetosphere is crucial to space science and space weather. For non-active periods, there is little agreement on where and how plasma entry into the magnetosphere might occur. Moreover, behaviour in the high-latitude region behind the magnetospheric cusps, for example, the lobes, is poorly understood, partly because of lack of coverage by previous space missions. Here, using Cluster multi-spacecraft data, we report an unexpected discovery of regions of solar wind entry into the Earth's high-latitude magnetosphere tailward of the cusps. From statistical observational facts and simulation analysis we suggest that these regions are most likely produced by magnetic reconnection at the high-latitude magnetopause, although other processes, such as impulsive penetration, may not be ruled out entirely. We find that the degree of entry can be significant for solar wind transport into the magnetosphere during such quiet times.

  6. Sensitive test for ion-cyclotron resonant heating in the solar wind.

    Science.gov (United States)

    Kasper, Justin C; Maruca, Bennett A; Stevens, Michael L; Zaslavsky, Arnaud

    2013-03-01

    Plasma carrying a spectrum of counterpropagating field-aligned ion-cyclotron waves can strongly and preferentially heat ions through a stochastic Fermi mechanism. Such a process has been proposed to explain the extreme temperatures, temperature anisotropies, and speeds of ions in the solar corona and solar wind. We quantify how differential flow between ion species results in a Doppler shift in the wave spectrum that can prevent this strong heating. Two critical values of differential flow are derived for strong heating of the core and tail of a given ion distribution function. Our comparison of these predictions to observations from the Wind spacecraft reveals excellent agreement. Solar wind helium that meets the condition for strong core heating is nearly 7 times hotter than hydrogen on average. Ion-cyclotron resonance contributes to heating in the solar wind, and there is a close link between heating, differential flow, and temperature anisotropy.

  7. Comparative Validation of Realtime Solar Wind Forecasting Using the UCSD Heliospheric Tomography Model

    Science.gov (United States)

    MacNeice, Peter; Taktakishvili, Alexandra; Jackson, Bernard; Clover, John; Bisi, Mario; Odstrcil, Dusan

    2011-01-01

    The University of California, San Diego 3D Heliospheric Tomography Model reconstructs the evolution of heliospheric structures, and can make forecasts of solar wind density and velocity up to 72 hours in the future. The latest model version, installed and running in realtime at the Community Coordinated Modeling Center(CCMC), analyzes scintillations of meter wavelength radio point sources recorded by the Solar-Terrestrial Environment Laboratory(STELab) together with realtime measurements of solar wind speed and density recorded by the Advanced Composition Explorer(ACE) Solar Wind Electron Proton Alpha Monitor(SWEPAM).The solution is reconstructed using tomographic techniques and a simple kinematic wind model. Since installation, the CCMC has been recording the model forecasts and comparing them with ACE measurements, and with forecasts made using other heliospheric models hosted by the CCMC. We report the preliminary results of this validation work and comparison with alternative models.

  8. Modeling Solar-Wind Heavy-Ions' Potential Sputtering of Lunar KREEP Surface

    Science.gov (United States)

    Barghouty, A. F.; Meyer, F. W.; Harris, R. P.; Adams, J. H., Jr.

    2012-01-01

    Recent laboratory data suggest that potential sputtering may be an important weathering mechanism that can affect the composition of both the lunar surface and its tenuous exosphere; its role and implications, however, remain unclear. Using a relatively simple kinetic model, we will demonstrate that solar-wind heavy ions induced sputtering of KREEP surfaces is critical in establishing the timescale of the overall solar-wind sputtering process of the lunar surface. We will also also show that potential sputtering leads to a more pronounced and significant differentiation between depleted and enriched surface elements. We briefly discuss the impacts of enhanced sputtering on the composition of the regolith and the exosphere, as well as of solar-wind sputtering as a source of hydrogen and water on the moon.

  9. A lunar penetrator to determine solar-wind-implanted resources at depth in the lunar regolith

    Science.gov (United States)

    Boynton, W.; Feldman, W.; Swindle, T.

    Several volatiles implanted into the lunar regolith by the solar wind are potentially important lunar resources. He-3 might be mined as a fuel for lunar nuclear fusion reactors. Even if the mining of He-3 turns out not to be feasible, several other elements commonly implanted by the solar wind (H,C, and N) could be important for life support and for propellant or fuel production for lunar bases. A simple penetrator-borne instrument package to measure the abundance of H at depth is proposed. Since solar-wind-implanted volatiles tend to correlate with one another, this can be used to estimate global inventories and to design extraction strategies for all of these species.

  10. The need for isotopic data on refractory elements in the solar wind

    Science.gov (United States)

    Manuel, O. K.

    1986-01-01

    The Sun accounts for the bulk of material in the solar system. Information on the isotopic composition of elements in the solar wind is therefore essential for an understanding of the contribution made by each nucleogenetic component that has been identified in meteorites. Recent work suggests that isotopic data on the solar wind may also help us to understand the physical process that is concentrating light elements at the solar surface. Refractory and volatile elements would behave alike under the conditions of solar fractionation. Prolonged exposure of foils at 1AU from the sun would be a relatively inexpensively way to collect the quantity of solar wind implanted refractory elements needed to test this hypothesis.

  11. Small-scale anisotropy and intermittency in high and low-latitude solar wind

    CERN Document Server

    Bigazzi, A; Gama, S M A; Velli, M

    2004-01-01

    We analyze low and high--latitude fast solar wind data from the Ulysses spacecraft from 1992 to 1994 using a a systematic method to analyse the anisotropic content of the magnetic field fluctuations. We investigate all available frequencies, 1-10^{-6} Hz, for both high and low--latitudes datasets and are able to quantify the relative importance of the anisotropic versus the isotropic fluctuations. We analyse, up to sixth order, longitudinal, transverse and mixed magnetic field correlations. Our results show that strongly intermittent and anisotropic events are present in the solar wind plasma at high frequencies/small scales, indicating the absence of a complete recovery of isotropy. Anisotropic scaling properties are compatible for high and low--latitude data, suggesting a universal behaviour in spite of the different rate of evolution of the fast solar wind streams in the two environments.

  12. Full-Sun observations for identifying the source of the slow solar wind

    CERN Document Server

    Brooks, David H; Warren, Harry P

    2016-01-01

    Fast (>700 km/s) and slow (~400 km/s) winds stream from the Sun, permeate the heliosphere and influence the near-Earth environment. While the fast wind is known to emanate primarily from polar coronal holes, the source of the slow wind remains unknown. Here we identify possible sites of origin using a slow solar wind source map of the entire Sun, which we construct from specially designed, full- disk observations from the Hinode satellite, and a magnetic field model. Our map provides a full-Sun observation that combines three key ingredients for identifying the sources: velocity, plasma composition and magnetic topology and shows them as solar wind composition plasma outflowing on open magnetic field lines. The area coverage of the identified sources is large enough that the sum of their mass contributions can explain a significant fraction of the mass loss rate of the solar wind.

  13. Solar wind energy transfer through the magnetopause of an open magnetosphere

    Science.gov (United States)

    Lee, L. C.; Roederer, J. G.

    1982-01-01

    An expression is derived for the total power, transferred from the solar wind to an open magnetosphere, which consists of the electromagnetic energy rate and the particle kinetic energy rate. The total rate of energy transferred from the solar wind to an open magnetosphere mainly consists of kinetic energy, and the kinetic energy flux is carried by particles, penetrating from the solar wind into the magnetosphere, which may contribute to the observed flow in the plasma mantle and which will eventually be convected slowly toward the plasma sheet by the electric field as they flow down the tail. While the electromagnetic energy rate controls the near-earth magnetospheric activity, the kinetic energy rate should dominate the dynamics of the distant magnetotail.

  14. Sources of the Slow Solar Wind During the Solar Cycle 23/24 Minimum

    Science.gov (United States)

    Kilpua, E. K. J.; Madjarska, M. S.; Karna, N.; Wiegelmann, T.; Farrugia, C.; Yu, W.; Andreeova, K.

    2016-09-01

    We investigate the characteristics and the sources of the slow ( {global coronal structure, including the frequent presence of low-latitude active regions in 2006 - 2007, long-lived low- and mid-latitude coronal holes in 2006 - mid-2008 and mostly the quiet Sun in 2009. We examined Carrington rotation averages of selected solar plasma, charge state, and compositional parameters and distributions of these parameters related to the quiet Sun, active region Sun, and the coronal hole Sun. While some of the investigated parameters (e.g. speed, the C+6/C+4 and He/H ratios) show clear variations over our study period and with solar wind source type, some (Fe/O) exhibit very little changes. Our results highlight the difficulty of distinguishing between the slow solar wind sources based on the inspection of solar wind conditions.

  15. Solar wind plasma profiles during interplanetary field enhancements (IFEs): Consistent with charged-dust pickup

    Science.gov (United States)

    Lai, H. R.; Wei, H. Y.; Russell, C. T.

    2013-06-01

    The solar wind contains many magnetic structures, and most of them have identifiable correlated changes in the flowing plasma. However, the very characteristic rise and fall of the magnetic field in an interplanetary field enhancement has no clear solar wind counterpart. It appears to be a pure magnetic ``barrier'' that transfers solar wind momentum to charged dust produced in collisions of interplanetary bodies in the size range of tens to hundreds of meters. This transfer lifts the fine scale dust out of the Sun's gravitational well. We demonstrate the lack of field-plasma correlation with several examples from spacecraft records as well as show an ensemble average velocity profile during IFEs which is consistent with our IFE formation hypothesis.

  16. Prediction of solar energetic particle event histories using real-time particle and solar wind measurements

    Science.gov (United States)

    Roelof, E. C.; Gold, R. E.

    1978-01-01

    The comparatively well-ordered magnetic structure in the solar corona during the decline of Solar Cycle 20 revealed a characteristic dependence of solar energetic particle injection upon heliographic longitude. When analyzed using solar wind mapping of the large scale interplanetary magnetic field line connection from the corona to the Earth, particle fluxes display an approximately exponential dependence on heliographic longitude. Since variations in the solar wind velocity (and hence the coronal connection longitude) can severely distort the simple coronal injection profile, the use of real-time solar wind velocity measurements can be of great aid in predicting the decay of solar particle events. Although such exponential injection profiles are commonplace during 1973-1975, they have also been identified earlier in Solar Cycle 20, and hence this structure may be present during the rise and maximum of the cycle, but somewhat obscured by greater temporal variations in particle injection.

  17. Azimuthally asymmetric ring current as a function of Dst and solar wind conditions

    Directory of Open Access Journals (Sweden)

    A. A. Ostapenko

    2004-09-01

    Full Text Available Based on magnetic data, spatial distribution of the westward ring current flowing at |z|<3 RE has been found under five levels of Dst, five levels of the interplanetary magnetic field (IMF z component, and five levels of the solar wind dynamic pressure Psw. The maximum of the current is located near midnight at distances 5 to 7 RE. The magnitude of the nightside and dayside parts of the westward current at distances from 4 to 9 RE can be approximated as Inight=1.75-0.041 Dst, Inoon=0.22-0.013 Dst, where the current is in MA. The relation of the nightside current to the solar wind parameters can be expressed as Inight=1.45-0.20 Bs IMF + 0.32 Psw, where BsIMF is the IMF southward component. The dayside ring current poorly correlates with the solar wind parameters.

  18. Models of Heliospheric solar wind charge exchange X-ray emission

    Science.gov (United States)

    Koutroumpa, Dimitra

    2016-04-01

    The first models of the solar wind charge exchange (SWCX) X-ray production in the heliosphere were developed shortly after the discovery of SWCX emission at the end of 1990s. Since then, continuous monitoring of the global solar wind evolution through the solar cycle has allowed better constraints on its interaction with the interstellar neutrals. We have a fairly accurate description of the interstellar neutral density distributions in interplanetary space. However, the solar wind heavy ion fluxes, and especially their short term variability and propagation through interplanetary space, have remained relatively elusive due to the sparseness or lack of in situ data, especially towards high ecliptic latitudes. In this talk, I will present a summary the heliospheric SWCX modeling efforts, and an overview of the global solar cycle variability of heliospheric SWCX emission, while commenting on the difficulties of modeling the real-time variability of the heliospheric X-ray signal.

  19. Acceleration of the solar wind in a spherical coordinate kinetic model

    Science.gov (United States)

    Dyadechkin, Sergey; Kallio, Esa; Alho, Markku; Semenov, Vladimir; Erkaev, Nikolay

    2015-04-01

    We have studied the acceleration of the solar wind protons by using a spherical coordinate kinetic hybrid model (HYBs). The model treats ions as particles while electrons form a massless, charge neutralizing fluid. The model includes the gravitation, the electron pressure and the jxB forces. We have studied a magnetized and a non-magnetized solar wind cases and performed simulations for different isothermal electron temperatures by using the same initial Maxwellian velocity distribution function for protons. We show in the presentation of how the bulk velocity, the plasma density, the electric potential and the velocity distribution function of protons depend on the radial distance from the Sun to several Astronomical Units. The derived velocity and density profiles are compared with those of the Parker's solar wind model. Finally, extensions of the model and its applicability for a space weather modelling are discussed.

  20. RECONSTRUCTING THE SOLAR WIND FROM ITS EARLY HISTORY TO CURRENT EPOCH

    Energy Technology Data Exchange (ETDEWEB)

    Airapetian, Vladimir S.; Usmanov, Arcadi V., E-mail: vladimir.airapetian@nasa.gov, E-mail: avusmanov@gmail.com [NASA Goddard Space Flight Center, Greenbelt, MD (United States)

    2016-02-01

    Stellar winds from active solar-type stars can play a crucial role in removal of stellar angular momentum and erosion of planetary atmospheres. However, major wind properties except for mass-loss rates cannot be directly derived from observations. We employed a three-dimensional magnetohydrodynamic Alfvén wave driven solar wind model, ALF3D, to reconstruct the solar wind parameters including the mass-loss rate, terminal velocity, and wind temperature at 0.7, 2, and 4.65 Gyr. Our model treats the wind thermal electrons, protons, and pickup protons as separate fluids and incorporates turbulence transport, eddy viscosity, turbulent resistivity, and turbulent heating to properly describe proton and electron temperatures of the solar wind. To study the evolution of the solar wind, we specified three input model parameters, the plasma density, Alfvén wave amplitude, and the strength of the dipole magnetic field at the wind base for each of three solar wind evolution models that are consistent with observational constrains. Our model results show that the velocity of the paleo solar wind was twice as fast, ∼50 times denser and 2 times hotter at 1 AU in the Sun's early history at 0.7 Gyr. The theoretical calculations of mass-loss rate appear to be in agreement with the empirically derived values for stars of various ages. These results can provide realistic constraints for wind dynamic pressures on magnetospheres of (exo)planets around the young Sun and other active stars, which is crucial in realistic assessment of the Joule heating of their ionospheres and corresponding effects of atmospheric erosion.

  1. Reconstructing the Solar Wind from Its Early History to Current Epoch

    Science.gov (United States)

    Airapetian, Vladimir S.; Usmanov, Arcadi V.

    2016-02-01

    Stellar winds from active solar-type stars can play a crucial role in removal of stellar angular momentum and erosion of planetary atmospheres. However, major wind properties except for mass-loss rates cannot be directly derived from observations. We employed a three-dimensional magnetohydrodynamic Alfvén wave driven solar wind model, ALF3D, to reconstruct the solar wind parameters including the mass-loss rate, terminal velocity, and wind temperature at 0.7, 2, and 4.65 Gyr. Our model treats the wind thermal electrons, protons, and pickup protons as separate fluids and incorporates turbulence transport, eddy viscosity, turbulent resistivity, and turbulent heating to properly describe proton and electron temperatures of the solar wind. To study the evolution of the solar wind, we specified three input model parameters, the plasma density, Alfvén wave amplitude, and the strength of the dipole magnetic field at the wind base for each of three solar wind evolution models that are consistent with observational constrains. Our model results show that the velocity of the paleo solar wind was twice as fast, ∼50 times denser and 2 times hotter at 1 AU in the Sun's early history at 0.7 Gyr. The theoretical calculations of mass-loss rate appear to be in agreement with the empirically derived values for stars of various ages. These results can provide realistic constraints for wind dynamic pressures on magnetospheres of (exo)planets around the young Sun and other active stars, which is crucial in realistic assessment of the Joule heating of their ionospheres and corresponding effects of atmospheric erosion.

  2. A Possible Cause of the Diminished Solar Wind During the Solar Cycle 23 - 24 Minimum

    Science.gov (United States)

    Liou, Kan; Wu, Chin-Chun

    2016-12-01

    Interplanetary magnetic field and solar wind plasma density observed at 1 AU during Solar Cycle 23 - 24 (SC-23/24) minimum were significantly smaller than those during its previous solar cycle (SC-22/23) minimum. Because the Earth's orbit is embedded in the slow wind during solar minimum, changes in the geometry and/or content of the slow wind region (SWR) can have a direct influence on the solar wind parameters near the Earth. In this study, we analyze solar wind plasma and magnetic field data of hourly values acquired by Ulysses. It is found that the solar wind, when averaging over the first (1995.6 - 1995.8) and third (2006.9 - 2008.2) Ulysses' perihelion ({˜} 1.4 AU) crossings, was about the same speed, but significantly less dense ({˜} 34 %) and cooler ({˜} 20 %), and the total magnetic field was {˜} 30 % weaker during the third compared to the first crossing. It is also found that the SWR was {˜} 50 % wider in the third ({˜} 68.5^deg; in heliographic latitude) than in the first ({˜} 44.8°) solar orbit. The observed latitudinal increase in the SWR is sufficient to explain the excessive decline in the near-Earth solar wind density during the recent solar minimum without speculating that the total solar output may have been decreasing. The observed SWR inflation is also consistent with a cooler solar wind in the SC-23/24 than in the SC-22/23 minimum. Furthermore, the ratio of the high-to-low latitude photospheric magnetic field (or equatorward magnetic pressure force), as observed by the Mountain Wilson Observatory, is smaller during the third than the first Ulysses' perihelion orbit. These findings suggest that the smaller equatorward magnetic pressure at the Sun may have led to the latitudinally-wider SRW observed by Ulysses in SC-23/24 minimum.

  3. A consistent thermodynamics of the MHD wave-heated two-fluid solar wind

    Directory of Open Access Journals (Sweden)

    I. V. Chashei

    Full Text Available We start our considerations from two more recent findings in heliospheric physics: One is the fact that the primary solar wind protons do not cool off adiabatically with distance, but appear to be heated. The other one is that secondary protons, embedded in the solar wind as pick-up ions, behave quasi-isothermal at their motion to the outer heliosphere. These two phenomena must be physically closely connected with each other. To demonstrate this we solve a coupled set of enthalpy flow conservation equations for the two-fluid solar wind system consisting of primary and secondary protons. The coupling of these equations comes by the heat sources that are relevant, namely the dissipation of MHD turbulence power to the respective protons at the relevant dissipation scales. Hereby we consider both the dissipation of convected turbulences and the dissipation of turbulences locally driven by the injection of new pick-up ions into an unstable mode of the ion distribution function. Conversion of free kinetic energy of freshly injected secondary ions into turbulence power is finally followed by partial reabsorption of this energy both by primary and secondary ions. We show solutions of simultaneous integrations of the coupled set of differential thermodynamic two-fluid equations and can draw interesting conclusions from the solutions obtained. We can show that the secondary proton temperature with increasing radial distance asymptotically attains a constant value with a magnitude essentially determined by the actual solar wind velocity. Furthermore, we study the primary proton temperature within this two-fluid context and find a polytropic behaviour with radially and latitudinally variable polytropic indices determined by the local heat sources due to dissipated turbulent wave energy. Considering latitudinally variable solar wind conditions, as published by McComas et al. (2000, we also predict latitudinal variations of primary proton temperatures at

  4. On the electron temperature downstream of the solar wind termination shock

    Directory of Open Access Journals (Sweden)

    I. V. Chashei

    2013-07-01

    Full Text Available In this paper we study the temperatures of electrons convected with the solar wind to large solar distances and finally transported over the solar wind termination shock. Nearly nothing, unless at high energies in the cosmic ray regime, is known about the thermodynamical behaviour of these distant electrons from in~situ plasma observations. Hence it is tacitly assumed these electrons, due to their adiabatic behaviour and vanishing heat conduction or energization processes, have rapidly cooled off to very low temperatures once they eventually arrive at the solar wind termination shock (at about 100 AU. In this paper we show that such electrons, however, at their passage over the termination shock due to the shock–electric field action undergo an over-adiabatic heating and therefore appear on the downstream side as a substantially heated plasma species. Looking quantitatively into this heating process we find that solar wind electrons achieve temperatures of the order of 2–4 × 106 K downstream of the termination shock, depending on the upstream solar wind bulk velocity and the shock compression ratio. Hence these electrons therewith play an important dynamical role in structuring this shock and determining the downstream plasma flow properties. Furthermore, they present an additional ionization source for incoming neutral interstellar hydrogen and excite X-ray emission. They also behave similar to cosmic ray electrons and extend to some limited region upstream of the shock of the order of 0.1 AU by spatial diffusion and thereby also modify the upstream solar wind properties.

  5. Dynamics of the Solar Wind Electromagnetic Energy Transmission Into Magnetosphere during Large Geomagnetic Storms

    Science.gov (United States)

    Kuznetsova, Tamara; Laptukhov, Alexej; Petrov, Valery

    Causes of the geomagnetic activity (GA) in the report are divided into temporal changes of the solar wind parameters and the changes of the geomagnetic moment orientation relative directions of the solar wind electric and magnetic fields. Based on our previous study we concluded that a reconnection based on determining role of mutual orientation of the solar wind electric field and geomagnetic moment taking into account effects of the Earth's orbital and daily motions is the most effective compared with existing mechanisms. At present a reconnection as paradigma that has applications in broad fields of physics needs analysis of experimental facts to be developed. In terms of reconnection it is important not only mutual orientation of vectors describing physics of interaction region but and reconnection rate which depends from rate of energy flux to those regions where the reconnection is permitted. Applied to magnetosphere these regions first of all are dayside magnetopause and polar caps. Influence of rate of the energy flux to the lobe magnetopause (based on calculations of the Poyting electromagnetic flux component controlling the reconnection rate along the solar wind velocity Pv) on planetary GA (Dst, Kp indices) is investigated at different phases of geomagnetic storms. We study also the rate of energy flux to the polar caps during storms (based on calculations of the Poyting flux vector component along the geomagnetic moment Pm) and its influence on magnetic activity in the polar ionosphere: at the auroral zone (AU,AL indices). Results allow to evaluate contributions of high and low latitude sources of electromagnetic energy to the storm development and also to clear mechanism of the electromagnetic energy transmission from the solar wind to the magnetosphere. We evaluate too power of the solar wind electromagnetic energy during well-known large storms and compare result with power of the energy sources of other geophysical processes (atmosphere, ocean

  6. Examining Periodic Solar-Wind Density Structures Observed in the SECCHI Heliospheric Imagers

    Science.gov (United States)

    Viall, Nicholeen M.; Spence, Harlan E.; Vourlidas, Angelos; Howard, Russell

    2010-01-01

    We present an analysis of small-scale, periodic, solar-wind density enhancements (length scales as small as approximately equals 1000 Mm) observed in images from the Heliospheric Imager (HI) aboard STEREO-A. We discuss their possible relationship to periodic fluctuations of the proton density that have been identified at 1 AU using in-situ plasma measurements. Specifically, Viall, Kepko, and Spence examined 11 years of in-situ solar-wind density measurements at 1 AU and demonstrated that not only turbulent structures, but also nonturbulent, periodic density structures exist in the solar wind with scale sizes of hundreds to one thousand Mm. In a subsequent paper, Viall, Spence, and Kasper analyzed the alpha-to-proton solar-wind abundance ratio measured during one such event of periodic density structures, demonstrating that the plasma behavior was highly suggestive that either temporally or spatially varying coronal source plasma created those density structures. Large periodic density structures observed at 1 AU, which were generated in the corona, can be observable in coronal and heliospheric white-light images if they possess sufficiently high density contrast. Indeed, we identify such periodic density structures as they enter the HI field of view and follow them as they advect with the solar wind through the images. The smaller, periodic density structures that we identify in the images are comparable in size to the larger structures analyzed in-situ at 1 AU, yielding further evidence that periodic density enhancements are a consequence of coronal activity as the solar wind is formed.

  7. A comparative study on 3-D solar wind structure observed by Ulysses and MHD simulation

    Institute of Scientific and Technical Information of China (English)

    FENG Xueshang; XIANG Changqing; ZHONG Dingkun; FAN Quanlin

    2005-01-01

    During Ulysses' first rapid pole-to-pole transit from September 1994 to June 1995, its observations showed that middle- or high-speed solar winds covered all latitudes except those between -20° and +20° near the ecliptic plane,where the velocity was 300-450 km/s. At poleward 40°,however, only fast solar winds at the speed of 700-870 km/s were observed. In addition, the transitions from low-speed wind to high-speed wind or vice versa were abrupt. In this paper, the large-scale structure of solar wind observed by Ulysses near solar minimum is simulated by using the three-dimensional numerical MHD model. The model combines TVD Lax-Friedrich scheme and MacCormack Ⅱ scheme and decomposes the calculation region into two regions: one from 1 to 22 Rs and the other from 18 Rs to 1 AU.Based on the observations of the solar photospheric magnetic field and an addition of the volumetric heating to MHD equations, the large-scale solar wind structure mentioned above is reproduced by using the three-dimensional MHD model and the numerical results are roughly consistent with Ulysses' observations. Our simulation shows that the initial magnetic field topology and the addition of volume heating may govern the bimodal structure of solar wind observed by Ulysses and also demonstrates that the three-dimensional MHD numerical model used here is efficient in modeling the large-scale solar wind structure.

  8. A statistical study on the correlations between plasma sheet and solar wind based on DSP explorations

    Directory of Open Access Journals (Sweden)

    G. Q. Yan

    2005-11-01

    Full Text Available By using the data of two spacecraft, TC-1 and ACE (Advanced Composition Explorer, a statistical study on the correlations between plasma sheet and solar wind has been carried out. The results obtained show that the plasma sheet at geocentric distances of about 9~13.4 Re has an apparent driving relationship with the solar wind. It is found that (1 there is a positive correlation between the duskward component of the interplanetary magnetic field (IMF and the duskward component of the geomagnetic field in the plasma sheet, with a proportionality constant of about 1.09. It indicates that the duskward component of the IMF can effectively penetrate into the near-Earth plasma sheet, and can be amplified by sunward convection in the corresponding region at geocentric distances of about 9~13.4 Re; (2 the increase in the density or the dynamic pressure of the solar wind will generally lead to the increase in the density of the plasma sheet; (3 the ion thermal pressure in the near-Earth plasma sheet is significantly controlled by the dynamic pressure of solar wind; (4 under the northward IMF condition, the ion temperature and ion thermal pressure in the plasma sheet decrease as the solar wind speed increases. This feature indicates that plasmas in the near-Earth plasma sheet can come from the magnetosheath through the LLBL. Northward IMF is one important condition for the transport of the cold plasmas of the magnetosheath into the plasma sheet through the LLBL, and fast solar wind will enhance such a transport process.

  9. Can the Solar Wind be Driven by Magnetic Reconnection in the Sun's Magnetic Carpet?

    Science.gov (United States)

    Cranmer, Steven R.; van Ballegooijen, Adriaan A.

    2010-09-01

    The physical processes that heat the solar corona and accelerate the solar wind remain unknown after many years of study. Some have suggested that the wind is driven by waves and turbulence in open magnetic flux tubes, and others have suggested that plasma is injected into the open tubes by magnetic reconnection with closed loops. In order to test the latter idea, we developed Monte Carlo simulations of the photospheric "magnetic carpet" and extrapolated the time-varying coronal field. These models were constructed for a range of different magnetic flux imbalance ratios. Completely balanced models represent quiet regions on the Sun and source regions of slow solar wind streams. Highly imbalanced models represent coronal holes and source regions of fast wind streams. The models agree with observed emergence rates, surface flux densities, and number distributions of magnetic elements. Despite having no imposed supergranular motions in the models, a realistic network of magnetic "funnels" appeared spontaneously. We computed the rate at which closed field lines open up (i.e., recycling times for open flux), and we estimated the energy flux released in reconnection events involving the opening up of closed flux tubes. For quiet regions and mixed-polarity coronal holes, these energy fluxes were found to be much lower than that which is required to accelerate the solar wind. For the most imbalanced coronal holes, the energy fluxes may be large enough to power the solar wind, but the recycling times are far longer than the time it takes the solar wind to accelerate into the low corona. Thus, it is unlikely that either the slow or fast solar wind is driven by reconnection and loop-opening processes in the magnetic carpet.

  10. Solar wind-magnetosphere coupling efficiency during ejecta and sheath-driven geomagnetic storms

    Science.gov (United States)

    Myllys, M.; Kilpua, E. K. J.; Lavraud, B.; Pulkkinen, T. I.

    2016-05-01

    We have investigated the effect of key solar wind driving parameters on solar wind-magnetosphere coupling efficiency during sheath and magnetic cloud-driven storms. The particular focus of the study was on the coupling efficiency dependence with Alfvén Mach number (MA). The efficiency has been estimated using the dawn-dusk component of the interplanetary electric field (EY), Newell and Borovsky functions as a proxy for the energy inflow and the polar cap potential (PCN), and auroral electrojet (AE) and SYM-H indices as the measure of the energy output. We have also performed a time delay analysis between the input parameters and the geomagnetic indices. The optimal time lag and smoothing window length depend on the coupling function used and on the solar wind driver. For example, turbulent sheaths are more sensitive to the time shift and the averaging interval than smoother magnetic clouds. The results presented in this study show that the solar wind-magnetosphere coupling efficiency depends strongly on the definition used, and it increases with increasing MA. We demonstrate that the PCN index distinctively shows both a Mach number dependent saturation and a Mach number independent saturation, pointing to the existence of at least two underlying physical mechanisms for the saturation of the index. By contrast, we show that the AE index saturates but that the saturation of this index is independent of the solar wind Mach number. Finally, we find that the SYM-H index does not seem to saturate and that the absence of saturation is independent of the Mach number regime. We highlight the difference between the typical MA conditions during sheath regions and magnetic clouds. The lowest MA values are related to the magnetic clouds. As a consequence, sheaths typically have higher solar wind-magnetosphere coupling efficiencies than magnetic clouds.

  11. Large plasmoids in global MHD simulations: Solar wind dependence and ionospheric mapping

    Science.gov (United States)

    Honkonen, Ilja; Palmroth, Minna; Pulkkinen, T.; Janhunen, Pekka

    The energy from the solar wind drives magnetospheric dynamics. An important, but the most difficult to measure, factor is the energy released in plasmoids. Plasmoids are large magnetic structures that form in the Earth's magnetotail during substorms, which are the main mecha-nism of extracting and releasing solar wind energy from the magnetosphere. During plasmoid formation the 3-d structure of the magnetotail becomes complicated, with spatially alternating closed and open magnetic topologies. While the formation and the release of plasmoids are unresolved, they are classically thought to detach from the magnetotail at the substorm onset. Using our global magnetohydrodynamic (MHD) simulation GUMICS-4, we investigate how different parameters of the solar wind affect the formation of plasmoids. Specifically we con-centrate on the role of the solar wind magnetic field parameters. We also investigate the solar wind dependence of plasmoid foot points, which are the end points of the plasmoid magnetic field in the ionosphere. Preliminary results suggest that plasmoid formation and plasmoid foot point location in the ionosphere strongly depend on the solar wind magnetic field param-eters. Our work may be of importance when interpreting some observed, but unexplained, ionospheric phenomena. We also present an operational definition of plasmoids, which enables their automatic detection in simulations. The project has received funding from the European Research Council under the European Community's Seventh Framework Programme (FP7/2007-2013) / ERC Starting Grant agree-ment number 200141-QuESpace. The work of IH and MP is supported by the Academy of Finland.

  12. Coronal holes near the equatorial plane and the solar wind abundance of iron

    Science.gov (United States)

    Ogilvie, K. W.; Coplan, M. A.; Yellin, K. A.

    1996-03-01

    Composition analysis of the solar wind from two equatorial coronal holes has been carried out with the Ion Composition Instrument on the ISEE-3 spacecraft. The abundances of oxygen, neon and iron were determined as coronal hole-related material flowed past the spacecraft. The results show that the edges of the hole-related flow are sharply defined with abundances closer to the abundances in the photosphere than in the slower solar wind. These results are similar to those found in flows from the southern polar coronal hole and suggest an underlying unity between the polar and equatorial regions of the sun.

  13. Response of Earth and Venus ionospheres to corotating solar wind stream of 3 July 1979

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, H.A. Jr.; Cloutier, P.A.; Dryer, M.; Suess, S.T.; Barnes, A.; Wolff, R.S.

    1985-06-01

    Corotating solar wind streams emanating from stable coronal structures provide an unique opportunity to compare the response of planetary ionospheres to the energy conveyed in the streams. For recurrent solar conditions the signal propagating outward along spiral paths in interplanetary space can at times exhibit rather similar content at quite different downstream locations in the ecliptic plane. Using solar wind measurements from plasma detectors on ISEE-3, Pioneer Venus Orbiter (PVO) and Helios-A, as well as in-situ ion composition measurements from Bennett Ion Mass Spectrometers on the Atmosphere Explorer-E and PVO spacecraft, corotating stream interactions are examined at Earth and Venus.

  14. Dependence of the cross polar cap potential saturation on the type of solar wind streams

    OpenAIRE

    Nikolaeva, N. S.; Yermolaev, Yu. I.; Lodkina, I. G.

    2013-01-01

    We compare of the cross polar cap potential (CPCP) saturation during magnetic storms induced by various types of the solar wind drivers. By using the model of Siscoe-Hill \\citep{Hilletal1976,Siscoeetal2002a,Siscoeetal2002b,Siscoeetal2004,Siscoe2011} we evaluate criteria of the CPCP saturation during the main phases of 257 magnetic storms ($Dst_{min} \\le -50$ nT) induced by the following types of the solar wind streams: magnetic clouds (MC), Ejecta, the compress region Sheath before MC ($Sh_{M...

  15. The entropy production at the multi-fluid MHD solar wind termination shock

    Energy Technology Data Exchange (ETDEWEB)

    Fahr, Hans Joerg; Siewert, Mark [Argelander Institut fuer Astronomie, Universitaet Bonn, Auf dem Huegel 71, 53121 Bonn (Germany)

    2014-07-01

    It has become evident meanwhile that the MHD solar wind termination shock needs a multifluid theoretical approach to adequately describe the intertwisted physical complexity in the interaction between fields and particles. In this approach here we treat the passage of three separate fluids over the MHD shock, namely solar wind protons, pickup protons and electrons. Connected with the different downstream pressures of three fluids we also calculate the different fluid entropies that are produced at the shock passage. As we can show the most relevant contribution to the total particle entropy is connected with the electron pressure which actually by far dominates the downstream plasma pressure.

  16. Investigation of the Large Scale Evolution and Topology of Coronal Mass Ejections in the Solar Wind

    Science.gov (United States)

    Riley, Peter

    1999-12-01

    This investigation is concerned with the large-scale evolution and topology of Coronal Mass Ejections (CMEs) in the solar wind. During this reporting period we have analyzed a series of low density intervals in the ACE (Advanced Composition Explorer) plasma data set that bear many similarities to CMEs. We have begun a series of 3D, MHD (Magnetohydrodynamics) coronal models to probe potential causes of these events. We also edited two manuscripts concerning the properties of CMEs in the solar wind. One was re-submitted to the Journal of Geophysical Research.

  17. One kilometer (1 km) electric solar wind sail tether produced automatically.

    Science.gov (United States)

    Seppänen, Henri; Rauhala, Timo; Kiprich, Sergiy; Ukkonen, Jukka; Simonsson, Martin; Kurppa, Risto; Janhunen, Pekka; Hæggström, Edward

    2013-09-01

    We produced a 1 km continuous piece of multifilament electric solar wind sail tether of μm-diameter aluminum wires using a custom made automatic tether factory. The tether comprising 90,704 bonds between 25 and 50 μm diameter wires is reeled onto a metal reel. The total mass of 1 km tether is 10 g. We reached a production rate of 70 m/24 h and a quality level of 1‰ loose bonds and 2‰ rebonded ones. We thus demonstrated that production of long electric solar wind sail tethers is possible and practical.

  18. Hot Oxygen Corona at Mars and Its Effect on Solar Wind Deceleration

    Institute of Scientific and Technical Information of China (English)

    ZHANG Tie-Long; Lichtenegger Herbert; SHI Jian-Kui; WANG Xiao; Lammer Helmut

    2006-01-01

    @@ Phobos 2 plasma measurements have revealed solar wind deceleration of about 100 km/s upstream of the Martian bow shock. It is suggested that the deceleration is due to the mass loading by the ions originating from the hot oxygen corona of Mars. In this study, we use a gas-dynamic model to estimate the solar wind deceleration caused by the mass loading effect and the result shows that the deceleration is only about 10-15 km/s when we invoke the well established hot oxygen corona density profiles.

  19. Effect of change in large and fast solar wind dynamic pressure on geosynchronous magnetic field

    Institute of Scientific and Technical Information of China (English)

    Borodkova N L; Liu Jing-Bo; Huang Zhao-Hui; Zastenker G N; Wang Chi; Eiges P E

    2006-01-01

    We present a comparison of changes in large and sharp solar wind dynamic pressure, observed by several spacecraft,with fast disturbances in the magnetospheric magnetic field, measured by the geosynchronous satellites. More than 260 changes in solar wind pressure during the period 1996-2003 are selected for this study. Large statistics show that an increase (a decrease) in dynamic pressure always results in an increase (a decrease) in the magnitude of geosynchronous magnetic field. The amplitude of response to the geomagnetic field strongly depends on the location of observer relative to the noon meridian, the value of pressure before disturbance, and the change in amplitude of pressure.

  20. Nonaxisymmetric anisotropy of solar wind turbulence as a direct test for models of magnetohydrodynamic turbulence.

    Science.gov (United States)

    Turner, A J; Gogoberidze, G; Chapman, S C

    2012-02-24

    Single point spacecraft observations of the turbulent solar wind flow exhibit a characteristic nonaxisymmetric anisotropy that depends sensitively on the perpendicular power spectral exponent. We use this nonaxisymmetric anisotropy as a function of wave vector direction to test models of MHD turbulence. Using Ulysses magnetic field observations in the fast, quiet polar solar wind we find that the Goldreich-Sridhar model of MHD turbulence is not consistent with the observed anisotropy, whereas the observations are well reproduced by the "slab+2D" model. The Goldreich-Sridhar model alone cannot account for the observations unless an additional component is also present.

  1. Single-Fluid 2D Magnetohydrodynamic Simulation of Solar Wind Structure in Comparison to Ulysses Observations

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Two dimensional Magnetohydrodynamic (MHD) equations with and without the momentum addi-tion respectively have been used to simulate the solar wind structure on the meridian plane. The results show that far away from the sun it isn't solar magnetic field that induces the concave solar wind speed. Instead, there may be the fast speed streamer driven by the momentum addition and an interface between high and low speed streamers. The interaction between high and low speed streamers causes the sharp division.

  2. Inertial-Range Reconnection in Magnetohydrodynamic Turbulence and in the Solar Wind.

    Science.gov (United States)

    Lalescu, Cristian C; Shi, Yi-Kang; Eyink, Gregory L; Drivas, Theodore D; Vishniac, Ethan T; Lazarian, Alexander

    2015-07-10

    In situ spacecraft data on the solar wind show events identified as magnetic reconnection with wide outflows and extended "X lines," 10(3)-10(4) times ion scales. To understand the role of turbulence at these scales, we make a case study of an inertial-range reconnection event in a magnetohydrodynamic simulation. We observe stochastic wandering of field lines in space, breakdown of standard magnetic flux freezing due to Richardson dispersion, and a broadened reconnection zone containing many current sheets. The coarse-grain magnetic geometry is like large-scale reconnection in the solar wind, however, with a hyperbolic flux tube or apparent X line extending over integral length scales.

  3. Multi-spacecraft measurement of anisotropic power levels and scaling in solar wind turbulence

    Directory of Open Access Journals (Sweden)

    K. T. Osman

    2009-08-01

    Full Text Available Measurements by the four Cluster spacecraft in the solar wind are used to determine quantitatively the field-aligned anisotropy of magnetohydrodynamic inertial range turbulence power levels and spectral indexes. We find, using time-lagged second order structure functions, that the spectral index is near 2 around the field-parallel direction, which is consistent with a "critical balance" turbulent cascade. Solar wind fluctuations are found to be anisotropic with power mainly in wavevectors perpendicular to the mean field, where the spectral index is around 5/3.

  4. Contributions to the Fourth Solar Wind Conference. [interplanetary magnetic fields and medium

    Science.gov (United States)

    Acuna, M. H.; Behannon, K. W.; Burlaga, L. F.; Lepping, R.; Ness, N.; Ogilvie, K.; Pizzo, J.

    1979-01-01

    Recent results in interplanetary physics are examined. These include observations of shock waves and post-shock magnetic fields made by Voyager 1, 2; observations of the electron temperature as a function of distance between 1.36 AU and 2.25 AU; and observations of the structure of sector boundaries observed by Helios 1. A theory of electron energy transport in the collisionless solar wind is presented, and compared with observations. Alfven waves and Alvenic fluctuations in the solar wind are also discussed.

  5. Pioneer 10 observation of the solar wind proton temperature heliocentric gradient

    Science.gov (United States)

    Mihalov, J. D.; Wolfe, J. H.

    1978-01-01

    Solar wind isotropic proton temperatures as measured out to 12.2 AU heliocentric distance by the Ames plasma analyzer aboard Pioneer 10 are presented as consecutive averages over three Carrington solar rotations and discussed. The weighted least-squares fit of average temperature to heliocentric radial distance, R, yields the power law R sup -.52. These average proton temperatures are not correlated as well with Pioneer 10's heliocentric radial distance (-.85) as are the corresponding average Zurich sunspot numbers R sub z (-.95). Consequently, it is difficult to isolate the spatial gradient in the Pioneer 10 solar wind proton temperatures using that data alone.

  6. Concentration of interstellar pickup H(+) and He(+) in the solar wind

    Science.gov (United States)

    Gloeckler, G.; Jokipii, J. R.; Giacalone, J.; Geiss, J.

    1994-01-01

    We present observations of interstellar pickup hydrogen and helium in the solar wind which show large, highly-correlated fluctuations in flux which are not correlated significantly with the solar-wind hydrogen flux. The correlation of the fluctuations in the two species implies that the fluctuations are caused by transport after ionization. The lack of correlation with the thermal flux means they are not caused by compressions of the wind. We present a new model which can naturally produce the observed fluctuations in the pickup ions.

  7. The interaction of the galactic cosmic rays with the high-speed solar wind streams

    Science.gov (United States)

    Klyuyeva, A. I.

    2014-12-01

    Based on statistical and comparative analysis of neutron monitor data from 1995 to 2013 years the influence of recurrent and sporadic high-speed streams of solar wind on the intensity of the galactic cosmic rays near Earth orbit was studied. Both types of high-speed solar wind streams modulate the galactic cosmic rays flux and cause Forbush decreases of different nature. The main parameters of Forbush decreases such as typical shape, magnitude, duration of decrease, delay, size of modulation area etc was studied.

  8. Comparison of Ring Current and Radiation Belt Responses during Transient Solar Wind Structures

    Science.gov (United States)

    Mulligan, T. L.; Roeder, J. L.; Lemon, C.; Fennell, J. F.

    2013-12-01

    The analysis of radiation belt dynamics provides insight into the physical mechanisms of trapping, energization, and loss of energetic particles in the magnetosphere. It is well known that the storm-time ring current response to solar wind drivers changes the magnetic field in the inner magnetosphere, which modifies radiation belt particle trajectories as well as the magnetopause and geomagnetic cutoff locations. What is not well known is the detailed space-time structure of solar wind transient features that drive the dynamics of the ring-current and radiation belt response. We compare observed responses of the ring current and radiation belts during two geomagnetic storms of similar intensity on 15 November 2012 and 29 June 2013. Using the self-consistent ring current model RCM-Equilibrium (RCM-E), which ensures a force-balanced ring-current response at each time step, we generate a simulated ring current in response to the changing conditions as the storm evolves on a timescale of hours. Observations of the plasma sheet particles, fields, and solar wind parameters are used to specify the dynamic boundary conditions as the storm evolves. This allows more realistic magnetospheric field and plasma dynamics during solar wind transients than can be obtained from existing empirical models. Using a spatial mapping algorithm developed by Mulligan et al., (2012) we create two-dimensional contour maps of the solar wind bulk plasma parameters using ACE, Wind, Geotail, and THEMIS data to quantitatively follow upstream spatial variations in the radial and azimuthal dimensions driving the storm. We perform a comparison of how the structure and impact angle of the solar wind transients affect the intensity and duration of energization of the ring current and radiation belt at various energies. We also investigate how the varying geomagnetic conditions determined by the solar wind affect dominant loss mechanisms such as magnetopause shadowing. Comparison of energetic particle

  9. Ultraviolet Coronagraph Spectroscopy: A Key Capability for Understanding the Physics of Solar Wind Acceleration

    CERN Document Server

    Cranmer, S R; Alexander, D; Bhattacharjee, A; Breech, B A; Brickhouse, N S; Chandran, B D G; Dupree, A K; Esser, R; Gary, S P; Hollweg, J V; Isenberg, P A; Kahler, S W; Ko, Y -K; Laming, J M; Landi, E; Matthaeus, W H; Murphy, N A; Oughton, S; Raymond, J C; Reisenfeld, D B; Suess, S T; van Ballegooijen, A A; Wood, B E

    2010-01-01

    Understanding the physical processes responsible for accelerating the solar wind requires detailed measurements of the collisionless plasma in the extended solar corona. Some key clues about these processes have come from instruments that combine the power of an ultraviolet (UV) spectrometer with an occulted telescope. This combination enables measurements of ion emission lines far from the bright solar disk, where most of the solar wind acceleration occurs. Although the UVCS instrument on SOHO made several key discoveries, many questions remain unanswered because its capabilities were limited. This white paper summarizes these past achievements and also describes what can be accomplished with next-generation instrumentation of this kind.

  10. Polar summer mesospheric extreme horizontal drift speeds during interplanetary corotating interaction regions (CIRs) and high-speed solar wind streams: Coupling between the solar wind and the mesosphere

    Science.gov (United States)

    Lee, Young-Sook; Kirkwood, Sheila; Kwak, Young-Sil; Kim, Kyung-Chan; Shepherd, Gordon G.

    2014-05-01

    We report the observation of echo extreme horizontal drift speed (EEHS, ≥ 300 m s-1) during polar mesospheric (80-90 km) summer echoes (PMSEs) by the VHF (52 MHz) radar at Esrange, Sweden, in years of 2006 and 2008. The EEHS occur in PMSEs as correlated with high-speed solar wind streams (HSSs), observed at least once in 12-17% of all hours of observation for the two summers. The EEHS rate peaks occur either during high solar wind speed in the early part of the PMSE season or during the arrival of interplanetary corotating interaction regions (CIRs) followed by peaks in PMSE occurrence rate after 1-4 days, in the latter part of the 2006 summer. The cause of EEHS rate peaks is likely under the competition between the interval of the CIR and HSS passage over the magnetosphere. A candidate process in producing EEHS is suggested to be localized strong electric field, which is caused by solar wind energy transfer from the interaction of CIR and HSS with the magnetosphere in a sequential manner. We suggest that EEHS are created by strong electric field, estimated as > 10-30 V m-1 at 85 km altitude, exceeding the mesospheric breakdown threshold field.

  11. Generalized Galilean Genesis

    CERN Document Server

    Nishi, Sakine

    2015-01-01

    The galilean genesis scenario is an alternative to inflation in which the universe starts expanding from Minkowski in the asymptotic past by violating the null energy condition stably. Several concrete models of galilean genesis have been constructed so far within the context of galileon-type scalar-field theories. We give a generic, unified description of the galilean genesis scenario in terms of the Horndeski theory, i.e., the most general scalar-tensor theory with second-order field equations. In doing so we generalize the previous models to have a new parameter (denoted by {\\alpha}) which results in controlling the evolution of the Hubble rate. The background dynamics is investigated to show that the generalized galilean genesis solution is an attractor, similarly to the original model. We also study the nature of primordial perturbations in the generalized galilean genesis scenario. In all the models described by our generalized genesis Lagrangian, amplification of tensor perturbations does not occur as ...

  12. Solar Wind Turbulence and Intermittency at 0.72 AU - Statistical Approach

    Science.gov (United States)

    Teodorescu, E.; Echim, M.; Munteanu, C.; Zhang, T.; Barabash, S. V.; Budnik, E.; Fedorov, A.

    2014-12-01

    Through this analysis we characterize the turbulent magnetic fluctuations by Venus Express Magnetometer, VEX-MAG in the solar wind during the last solar cycle minimum at a distance of 0.72 AU from the Sun. We analyze data recorded between 2007 and 2009 with time resolutions of 1 Hz and 32 Hz. In correlation with plasma data from the ASPERA instrument, Analyser of Space Plasma and Energetic Atoms, we identify 550 time intervals, at 1 Hz resolution, when VEX is in the solar wind and which satisfy selection criteria defined based on the amount and the continuity of the data. We identify 118 time intervals that correspond to fast solar wind. We compute the power spectral densities (PSD) for Bx, By, Bz, B, B2, B|| and B^. We perform a statistical analysis of the spectral indices computed for each of the PSD's and evidence a dependence of the spectral index on the solar wind velocity and a slight difference in power content between parallel and perpendicular components of the magnetic field. We also estimate the scale invariance of fluctuations by computing the Probability Distribution Functions (PDFs) for Bx, By, Bz, B and B2 time series and discuss the implications for intermittent turbulence. Research supported by the European Community's Seventh Framework Programme (FP7/2007-2013) under grant agreement no 313038/STORM, and a grant of the Romanian Ministry of National Education, CNCS - UEFISCDI, project number PN-II-ID-PCE-2012-4-0418.

  13. Shrinkage of magnetosphere observed by TC-1 satellite during the high-speed solar wind stream

    Institute of Scientific and Technical Information of China (English)

    LI LiuYuan; CAO JinBin; ZHOU GuoCheng; YANG JunYing; YAN ChunXiao; ZHANG TieLong; H. REME; I. DANDOURAS; C. M. CARR

    2008-01-01

    During the interval 06:14-07:30 UT on August 24, 2005, since the Earth's magneto-pause was suddenly compressed by the persistent high-speed solar wind stream with the southward component of the interplanetary magnetic field (IMF), the magnetopause moved Inward for about 3.1 RE. Meanwhile, TC-1 satellite shifted from northern plasma sheet to the northern lobe/mantle region, although it kept Inward flying during the Interval 06:00-07:30UT. The shift of TC-1 from the plasma sheet to the lobe/mantle is caused by the simultaneous inward displacements of the plasma sheet and near-Earth lobe/mantle region, and their inward movement velocity is larger than the inward motion velocity of TC-1. The Joint inward dis-placements of the magnetopause, the lobe/mantle region and the plasma sheet indicate that the whole magnetosphere shrinks inward due to the magnetospheric compression by the high-speed solar wind stream, and the magnetospheric ions are attached to the magnetic field lines (i.e. 'frozen' in magnetic field) and move inward in the shrinking process of magnetosphere. The large shrinkage of magne-tosphere indicates that the near-Earth magnetotail compression caused by the strong solar wind dynamic pressure is much larger than its thickening caused by the southward component of the IMF, and the locations of magnetospheric regions with different plasmas vary remarkably with the variation of the solar wind dynamic pressure.

  14. Solar wind density structure at 1 AU and comparison to Doppler scintillation measurements

    Science.gov (United States)

    Huddleston, D. E.; Woo, R.; Neugebauer, M.

    1996-07-01

    Results of a survey of solar wind density fluctuations in different flow types observed by ISEE-3 at 1 AU are presented and compared with Doppler scintillation measurements. We consider coronal hole, plasma sheet, interstream, CME and sheath interaction region flow types. For the quasi-stationary solar wind, densities (N) and density fluctuation levels (ΔN) are low in coronal hole flow, and high in the plasma sheet containing the heliospheric current sheet (HCS). The highest fluctuation levels are found in the sheath compression regions between CMEs and associated forward shocks. The streamer structure around the HCS broadens and erodes with distance from the Sun, and the broadened Doppler scintillation signature at 1 AU is in good qualitative agreement with ISEE-3 superposed epoch analysis. The observed asymmetry about the HCS is an expected result of solar wind dynamic evolution. A greater contrast between flow types is seen in ΔN levels rather than in N itself. Doppler scintillation responds to ΔN and thus provides a sensitive means of detecting interplanetary disturbances. However, we find that ΔN/N is not constant in the solar wind, and thus enhanced scintillation cannot unambiguously imply enhanced density.

  15. The Level of Turbulence in the Solar Wind and the Driving of the Earth's Magnetosphere

    Science.gov (United States)

    Borovsky, J. E.; Gosling, J. T.

    2001-05-01

    Times when the level of magnetic-field fluctuations in the solar wind are very small (IMF calm) are compared with "normal" times (IMF noisy). Using ISEE-3 and ISEE-2 data, for a given value of solar-wind vBz, it is found that the auroral electrojet indices AE, AU, and AL and the planetary index KP are substantial reduced in magnitude when the IMF is calm. This is particularly true for times when the IMF Bz is northward. An analogy is explored between the solar-wind-driven magnetosphere and laboratory fluid-flow experiments in which the drag on an obstacle in the flow and the structure of the fluid wake behind the obstacle are varied by injecting turbulence of various amplitudes in the upstream fluid. The laboratory results are explained with the concept that turbulent eddy viscosity, which is a function of the turbulence amplitude, controls the coupling of the fluid to the obstacle. This eddy-viscosity-coupling concept is explored for the solar-wind driving the magnetosphere via the magnetosheath. A clue as to why SMCs (steady magnetospheric convection events) occur may be uncovered.

  16. Interaction of suprathermal solar wind electron fluxes with sheared whistler waves: fan instability

    Directory of Open Access Journals (Sweden)

    C. Krafft

    Full Text Available Several in situ measurements performed in the solar wind evidenced that solar type III radio bursts were some-times associated with locally excited Langmuir waves, high-energy electron fluxes and low-frequency electrostatic and electromagnetic waves; moreover, in some cases, the simultaneous identification of energetic electron fluxes, Langmuir and whistler waves was performed. This paper shows how whistlers can be excited in the disturbed solar wind through the so-called "fan instability" by interacting with energetic electrons at the anomalous Doppler resonance. This instability process, which is driven by the anisotropy in the energetic electron velocity distribution along the ambient magnetic field, does not require any positive slope in the suprathermal electron tail and thus can account for physical situations where plateaued reduced electron velocity distributions were observed in solar wind plasmas in association with Langmuir and whistler waves. Owing to linear calculations of growth rates, we show that for disturbed solar wind conditions (that is, when suprathermal particle fluxes propagate along the ambient magnetic field, the fan instability can excite VLF waves (whistlers and lower hybrid waves with characteristics close to those observed in space experiments.

    Key words. Space plasma physics (waves and instabilities – Radio Science (waves in plasma – Solar physics, astrophysics and astronomy (radio emissions

  17. Evolution of Intermittency in the Slow and Fast Solar Wind Beyond the Ecliptic Plane

    CERN Document Server

    Wawrzaszek, Anna; Macek, Wiesław M; Bruno, Roberto

    2016-01-01

    We study intermittency as a departure from self-similarity of the solar wind magnetic turbulence and investigate the evolution with the heliocentric distance and latitude. We use data from the Ulysses spacecraft measured during two solar minima (1997-1998 and 2007-2008) and one solar maximum (1999-2001). In particular, by modeling a multifractal spectrum, we revealed the intermittent character of turbulence in the small-scale fluctuations of the magnetic field embedded in the slow and fast solar wind. Generally, at small distances from the Sun, in both the slow and fast solar wind, we observe the high degree of multifractality (intermittency) that decreases somewhat slowly with distance and slowly with latitude. The obtained results seem to suggest that generally intermittency in the solar wind has a solar origin. However, the fast and slow streams, shocks, and other nonlinear interactions can only be considered as the drivers of the intermittent turbulence. It seems that analysis shows that turbulence beyond...

  18. Pick-up ion pressure gradients modulating the solar wind dynamics

    Science.gov (United States)

    Fahr, Hans J.; Fichtner, Horst

    1995-01-01

    Neutral interstellar atoms penetrate deeply into the inner heliosphere before they become ionized by various processes. As ions they are picked-up by the frozen-in magnetic fields and are convected outwards with the solar wind plasma. Thereby the primary plasma flow is mass, momentum, and energy-loaded. The dynamics of the distant multi-constituent solar wind is, however, not solely determined by these loading processes, but is also affected by the wave-mediated pick-up ion pressure gradients derivable from the pick-up ion distribution function. The action of the radial components of these pressures essentially counter balances the decelerating effect of the solar wind momentum loading, diminishing strongly the deceleration of the distant solar wind. Furthermore the latitudinal components of the pick-up ion pressures induce latitudinal forces acting on the multiconstituent solar plasma outflow and inducing nonradial bulk flow components. The enforced nonradial outflow geometry on the upwind hemisphere may partly be responsible for the magnetic flux deficit which was claimed since several years in the PIONEER-10 magnetic flux data.

  19. X-ray Magnetosheath Emission from Solar Wind Charge Exchange During Two CME Events in 2001

    Science.gov (United States)

    Sembay, S.; Whittaker, I. C.; Read, A.; Carter, J. A.; Milan, S. E.; Palmroth, M.

    2016-12-01

    Using a combination of the GUMICS-4 MHD model and observed solar wind heavy ion abundances from ACE, we produce case studies looking at X-ray emission from charge exchange in the Earth's magnetosheath. We specifically look in the 0.5-0.7 keV range, which is dominated by highly ionised oxygen emission. Previous studies looking at solar wind charge exchange (SWCX) emission have verified our modelling process via comparison to the XMM-Newton X-ray observatory, and we use the same simulation process here. This study investigates the emission magnitude changes that occur during two coronal mass ejection (CME) events (31 March 2001 and 21 October 2001). As part of this work we also provide a novel masking technique to exclude the plasma of terrestrial origin in the MHD model. As expected the two CME cases examined provide an increased dynamic pressure which pushes the magnetopause closer to the Earth, with a high temporal variation. We show how these changes cause an increase in the peak SWCX emission signature by over an order of magnitude from the quiescent solar wind case. Imaging of this SWCX emission allows a global view of the magnetopause shape and position, a technique planned for future missions such as SMILE (Solar wind Magnetosphere Ionosphere Link Explorer).

  20. Investigation of solar wind source regions using Ulysses composition data and a PFSS model

    Science.gov (United States)

    Peleikis, Thies; Kruse, Martin; Berger, Lars; Drews, Christian; Wimmer-Schweingruber, Robert F.

    2016-03-01

    In this work we study the source regions for different solar wind types. While it is well known that the fast solar wind originates from inside Coronal Holes, the source regions for the slow solar wind are still under debate. For our study we use Ulysses compositional and plasma measurements and map them back to the solar corona. Here we use a potential field source surface model to model the coronal magnetic field. On the source surface we assign individual open field lines to the ballistic foot points of Ulysses. We do not only consider the photospheric origin of these field lines, but rather attempt to trace them across several height levels through the corona. We calculate the proximity of the field lines to the coronal hole border for every height level. The results are height profiles of these field lines. By applying velocity and charge state ratio filters to the height profiles, we can demonstrate that slow wind is produced close to the coronal hole border. In particular, we find that not only the proximity to the border matters, but also that the bending of the field lines with respect to the coronal hole border plays a crucial role in determining the solar wind type.