Search

Your search keyword '"Hirahara, M."' showing total 159 results
Start Over Author "Hirahara, M." Language english
159 results on '"Hirahara, M."'

1. Investigating Mercury’s Environment with the Two-Spacecraft BepiColombo Mission

Author

Milillo, A., Fujimoto, M., Murakami, G., Benkhoff, J., Zender, J., Aizawa, S., Dósa, M., Griton, L., Heyner, D., Ho, G., Imber, S. M., Jia, X., Karlsson, T., Killen, R. M., Laurenza, M., Lindsay, S. T., McKenna-Lawlor, S., Mura, A., Raines, J. M., Rothery, D. A., André, N., Baumjohann, W., Berezhnoy, A., Bourdin, P. A., Bunce, E. J., Califano, F., Deca, J., de la Fuente, S., Dong, C., Grava, C., Fatemi, S., Henri, P., Ivanovski, S. L., Jackson, B. V., James, M., Kallio, E., Kasaba, Y., Kilpua, E., Kobayashi, M., Langlais, B., Leblanc, F., Lhotka, C., Mangano, V., Martindale, A., Massetti, S., Masters, A., Morooka, M., Narita, Y., Oliveira, J. S., Odstrcil, D., Orsini, S., Pelizzo, M. G., Plainaki, C., Plaschke, F., Sahraoui, F., Seki, K., Slavin, J. A., Vainio, R., Wurz, P., Barabash, S., Carr, C. M., Delcourt, D., Glassmeier, K.-H., Grande, M., Hirahara, M., Huovelin, J., Korablev, O., Kojima, H., Lichtenegger, H., Livi, S., Matsuoka, A., Moissl, R., Moncuquet, M., Muinonen, K., Quèmerais, E., Saito, Y., Yagitani, S., Yoshikawa, I., and Wahlund, J.-E.

Published
2020
Full Text
View/download PDF

8. Flux Enhancements of Field-Aligned Low-Energy O^+ Ion (FALEO) in the Inner Magnetosphere: A Possible Source of Warm Plasma Cloak and Oxygen Torus

Author

Nosé, M., Matsuoka, A., Miyoshi, Y., Asamura, K., Hori, T., Teramoto, M., Shinohara, I., Hirahara, M., Kletzing, C. A., Smith, C. W., MacDowall, R. J., Spence, H. E., Reeves, G. D., and Gjerloev, J. W.

Abstract

Flux enhancements of field-aligned low-energy O^+ ion (FALEO) are simultaneously observed by Arase, Van Allen Probes A and B in the nightside inner magnetosphere during 05–07 UT on September 22, 2018. FALEOs appear after a magnetic dipolarization signature with approximately 6–20 min delay. It has the energy-dispersion signature from a few keV to ∼100 eV only in the direction parallel to the magnetic field at Arase, while it decreases its energy from a few keV down to 10 eV in both the parallel and antiparallel directions at Probes A and B. We perform a numerical simulation to trace trajectories of test O^+ ions in a model magnetosphere, which are launched from above the ionosphere 3–15 min after a substorm. Flying virtual satellites that have the same orbits as the real satellites, we create virtual energy-time spectrograms of O^+ ions to compare with the observed ones. Results show a very good correspondence between them, indicating that FALEOs originate from ionospheric O^+ ions that are extracted from the upper ionosphere at substorm onset and flow along the magnetic field toward the geomagnetic equator. It is also revealed that 3–9 hr after their launch, test O^+ ions less than 400 eV have a spatial distribution in the inner magnetosphere which is similar to those of the warm plasma cloak and the oxygen torus. We therefore conclude that FALEO is a source of those cold ion populations.

Published
2022

12. Field-Aligned Low-Energy O^+ Flux Enhancements in the Inner Magnetosphere Observed by Arase

Author

Nosé, M., Matsuoka, A., Miyoshi, Y., Asamura, K., Hori, T., Teramoto, M., Shinohara, I., and Hirahara, M.

Subjects
Physics::Space Physics
Abstract

The present study examines the low-energy ion flux variations observed by the Arase satellite in the inner magnetosphere. From the magnetic field and ion flux data obtained by the fluxgate magnetometer and the low-energy particle experiments–ion mass analyzer onboard Arase, we find 55 events of the low-energy O^+ flux enhancement accompanied with magnetic field dipolarization in the periods of April 1–October 31, 2017 and July 1, 2018–January 31, 2019. The low-energy O^+ flux enhancements (a) start a few minutes after the dipolarization onset, (b) have energy-dispersed signatures with decreasing energy from a few keV down to ∼10 eV, (c) are observed in both storm and non-storm periods, (d) have a field-aligned distribution (α ∼ 0° in the southern hemisphere and α ∼ 180° in the northern hemisphere), (e) are accompanied by the low-energy H^+ flux enhancements that have lower energies than O^+ by a factor of 3–10, and (f) increase the O^+ density and the O^+/H^+ density ratio by ∼10 times and 4–5 times, respectively. We perform a numerical simulation to trace ion trajectories forward in time from the Arase positions. It is revealed that both H^+ and O^+ ions drift eastward and reach the dawn-to-morning sector without being lost in the ionosphere, if the pitch angle scattering effect is considered near the equatorial plane. This result suggests that these low-energy field-aligned ions can contribute to formation of the warm plasma cloak.

Published
2021

15. Flux Enhancements of Field‐Aligned Low‐Energy O+ Ion (FALEO) in the Inner Magnetosphere: A Possible Source of Warm Plasma Cloak and Oxygen Torus.

Author

Nosé, M., Matsuoka, A., Miyoshi, Y., Asamura, K., Hori, T., Teramoto, M., Shinohara, I., Hirahara, M., Kletzing, C. A., Smith, C. W., MacDowall, R. J., Spence, H. E., Reeves, G. D., and Gjerloev, J. W.

Subjects
OXYGEN plasmas, MAGNETOSPHERE, PLASMA sources, TORUS, PHYSIOLOGICAL transport of oxygen, GEOMAGNETISM
Abstract

Flux enhancements of field‐aligned low‐energy O+ ion (FALEO) are simultaneously observed by Arase, Van Allen Probes A and B in the nightside inner magnetosphere during 05–07 UT on September 22, 2018. FALEOs appear after a magnetic dipolarization signature with approximately 6–20 min delay. It has the energy‐dispersion signature from a few keV to ∼100 eV only in the direction parallel to the magnetic field at Arase, while it decreases its energy from a few keV down to 10 eV in both the parallel and antiparallel directions at Probes A and B. We perform a numerical simulation to trace trajectories of test O+ ions in a model magnetosphere, which are launched from above the ionosphere 3–15 min after a substorm. Flying virtual satellites that have the same orbits as the real satellites, we create virtual energy‐time spectrograms of O+ ions to compare with the observed ones. Results show a very good correspondence between them, indicating that FALEOs originate from ionospheric O+ ions that are extracted from the upper ionosphere at substorm onset and flow along the magnetic field toward the geomagnetic equator. It is also revealed that 3–9 hr after their launch, test O+ ions less than 400 eV have a spatial distribution in the inner magnetosphere which is similar to those of the warm plasma cloak and the oxygen torus. We therefore conclude that FALEO is a source of those cold ion populations. Key Points: Flux enhancements of field‐aligned low‐energy O+ ion (FALEO) are simultaneously observed by Arase, Van Allen Probes A and BNumerical simulation well reproduces observed energy‐time spectrograms of FALEO with the energy‐dispersed signature from 1 keV to 10 eVFALEO is a source of the warm plasma cloak and the oxygen torus that appear in the dawn to noon sectors [ABSTRACT FROM AUTHOR]

Published
2022
Full Text
View/download PDF

18. Field‐Aligned Low‐Energy O+ Flux Enhancements in the Inner Magnetosphere Observed by Arase.

Author

Nosé, M., Matsuoka, A., Miyoshi, Y., Asamura, K., Hori, T., Teramoto, M., Shinohara, I., and Hirahara, M.

Subjects
MAGNETOSPHERE, MAGNETIC fields, FLUXGATE magnetometers, STORMS, IONOSPHERE
Abstract

The present study examines the low‐energy ion flux variations observed by the Arase satellite in the inner magnetosphere. From the magnetic field and ion flux data obtained by the fluxgate magnetometer and the low‐energy particle experiments–ion mass analyzer onboard Arase, we find 55 events of the low‐energy O+ flux enhancement accompanied with magnetic field dipolarization in the periods of April 1–October 31, 2017 and July 1, 2018–January 31, 2019. The low‐energy O+ flux enhancements (a) start a few minutes after the dipolarization onset, (b) have energy‐dispersed signatures with decreasing energy from a few keV down to ∼10 eV, (c) are observed in both storm and non‐storm periods, (d) have a field‐aligned distribution (α ∼ 0° in the southern hemisphere and α ∼ 180° in the northern hemisphere), (e) are accompanied by the low‐energy H+ flux enhancements that have lower energies than O+ by a factor of 3–10, and (f) increase the O+ density and the O+/H+ density ratio by ∼10 times and 4–5 times, respectively. We perform a numerical simulation to trace ion trajectories forward in time from the Arase positions. It is revealed that both H+ and O+ ions drift eastward and reach the dawn‐to‐morning sector without being lost in the ionosphere, if the pitch angle scattering effect is considered near the equatorial plane. This result suggests that these low‐energy field‐aligned ions can contribute to formation of the warm plasma cloak. Key Points: O+ flux enhancements that have energy‐dispersed signatures at <∼5 keV appear a few minutes after magnetic field dipolarizationThe lowest energy of ∼10 eV and a field‐aligned distribution of the O+ flux enhancements suggest prompt extraction from the ionosphereThe field‐aligned low‐energy O+ flux enhancements can be a source of the warm plasma cloak [ABSTRACT FROM AUTHOR]

Published
2021
Full Text
View/download PDF

20. Ground-based observations of diffuse auroral structures in conjunction with Reimei measurements

Author

Samara, M., Michell, R. G., Hampton, D. L., Stenbaek-Nielsen, H. C., Asamura, Kazushi, and Hirahara, M.

Subjects
Atmospheric Science, 010504 meteorology & atmospheric sciences, Electron precipitation, Astrophysics, Electron, 01 natural sciences, 010305 fluids & plasmas, Relativistic particle, 0103 physical sciences, Earth and Planetary Sciences (miscellaneous), lcsh:Science, Image resolution, 0105 earth and related environmental sciences, Physics, Satellite observation, Conjunction (astronomy), lcsh:QC801-809, Geology, Astronomy and Astrophysics, Geophysics, lcsh:QC1-999, lcsh:Geophysics. Cosmic physics, Space and Planetary Science, Satellite, lcsh:Q, lcsh:Physics
Abstract

Accepted: 2010-03-23, 資料番号: SA1002582000

Published
2018

21. Energy Transfer Between Hot Protons and Electromagnetic Ion Cyclotron Waves in Compressional Pc5 Ultra‐low Frequency Waves.

Author

Kitamura, N., Shoji, M., Nakamura, S., Kitahara, M., Amano, T., Omura, Y., Hasegawa, H., Boardsen, S. A., Miyoshi, Y., Katoh, Y., Teramoto, M., Saito, Y., Yokota, S., Hirahara, M., Gershman, D. J., Giles, B. L., Russell, C. T., Strangeway, R. J., Ahmadi, N., and Lindqvist, P.‐A.

Subjects
SPACE exploration, ELECTROMAGNETIC fields, CYCLOTRONS, MAGNETIC fields
Abstract

The Magnetospheric Multiscale (MMS) spacecraft observed many enhancements of electromagnetic ion cyclotron (EMIC) waves in an event in the late afternoon outer magnetosphere. These enhancements occurred mainly in the troughs of magnetic field intensity associated with a compressional ultralow frequency (ULF) wave. The ULF wave had a period of ∼2–5 min (Pc5 frequency range) and was almost static in the plasma rest frame. The magnetic and ion pressures were in antiphase. They are consistent with mirror‐mode type structures. We apply the Wave‐Particle Interaction Analyzer method, which can quantitatively investigate the energy transfer between hot anisotropic protons and EMIC waves, to burst‐mode data obtained by the four MMS spacecraft. The energy transfer near the cyclotron resonance velocity was identified in the vicinity of the center of troughs of magnetic field intensity, which corresponds to the maxima of ion pressure in the compressional ULF wave. This result is consistent with the idea that the EMIC wave generation is modulated by ULF waves, and preferential locations for the cyclotron resonant energy transfer are the troughs of magnetic field intensity. In these troughs, relatively low resonance velocity due to the lower magnetic field intensity and the enhanced hot proton flux likely contribute to the enhanced energy transfer from hot protons to the EMIC waves by cyclotron resonance. Due to the compressional ULF wave, regions of the cyclotron resonant energy transfer can be narrow (only a few times of the gyroradii of hot resonant protons) in magnetic local time. Key Points: Electromagnetic ion cyclotron wave enhancements were detected in a compressional ultralow frequency (ULF) waveTroughs of magnetic field intensity of the ULF wave are preferential locations for the cyclotron resonant energy transferDue to compressional ULF wave, regions of the cyclotron resonant energy transfer can be narrow in magnetic local time [ABSTRACT FROM AUTHOR]

Published
2021
Full Text
View/download PDF

22. Relationship of Topside Ionospheric Ion Outflows to Auroral Forms and Precipitation, Plasma Waves, and Convection Observed by Polar

Author

Hirahara, M, Horwitz, J. L, Moore, T. E, Germany, G. A, Spann, J. F, Peterson, W. K, Shelley, E. G, Chandler, M. O, Giles, B. L, Craven, P. D, Pollock, C. J, Gurnett, D. A, Pickett, J. S, Persoon, A. M, Scudder, J. D, Maynard, N. C, Mozer, F. S, Brittnacher, M. J, and Nagai, T

Subjects
Geophysics
Abstract

The POLAR satellite often observes upflowing ionospheric ions (UFIs) in and near the aurora] oval on southern perigee (approx. 5000 km altitude) passes. We present the UFI features observed by the thermal ion dynamics experiment (TIDE) and the toroidal imaging mass angle spectrograph (TIMAS) in the dusk-dawn sector under two different geomagnetic activity conditions in order to elicit their relationships with auroral forms, wave emissions, and convection pattern from additional POLAR instruments. During the active interval, the ultraviolet imager (UVI) observed a bright discrete aurora on the duskside after the substorm onset and then observed a small isolated aurora form and diffuse auroras on the dawnside during the recovery phase. The UFIs showed clear conic distributions when the plasma wave instrument (PWI) detected strong broadband wave emissions below approx. 10 kHz, while no significant auroral activities were observed by UVI. At higher latitudes, the low-energy UFI conics gradually changed to the polar wind component with decreasing intensity of the broadband emissions. V-shaped auroral kilometric radiation (AKR) signatures observed above -200 kHz by PWI coincided with the region where the discrete aurora and the UFI beams were detected. The latitude of these features was lower than that of the UFI conics. During the observations of the UFI beams and conics, the lower-frequency fluctuations observed by the electric field instrument were also enhanced, and the convection directions exhibited large fluctuations. It is evident that large electrostatic potential drops produced the precipitating electrons and discrete auroras, the UFI beams, and the AKR, which is also supported by the energetic plasma data from HYDRA. Since the intense broadband emissions were also observed with the UFIs, the ionospheric ions could be energized transversely before or during the parallel acceleration due to the potential drops.

Published
1998
Full Text
View/download PDF

23. Survey of the Polar Wind near 1 and 8Re with POLAR

Author

Horwitz, J. L, Su, Y. J, Moore, Thomas E, Giles, Barbara L, Craven, Paul D, Chandler, Michael O, Hirahara, M, and Pollock, Craig J

Subjects
Meteorology And Climatology
Abstract

Recent theoretical/modeling developments as well as measurements by Akebono and other spacecraft have created renewed interest in the polar wind. This interest arises generally from two principal aspects: (a) Understanding the physics of such plausible influences as photo-electron-driven parallel electric fields and convection-driven centrifugal acceleration on the polar wind transport; and (b) Understanding the intermediate fate of the polar wind--in particular, its contribution to the plasma content of such magnetospheric domains as the plasma sheet and tail lobes. In this talk, we will describe the results of a new survey of the intermediate(lR(sub E)) and high(8 R(sub E)) polar wind, based on high-resolution core ion measurements with the Thermal Ion Dynamics Experiment(TIDE) on POLAR. These new measurements of H(+), He(+), and O(+) densities, parallel flow velocities, Mach numbers and fluxes, and parallel and perpendicular temperatures, will be used to explore such issues as: (1) Supersonic vs. subsonic polar wind flows; (2) Upward and downward O(+) flows, and the origin of the polar cap ions; (3) Parallel flow speeds for various polar wind ion species in the context of various acceleration/transport mechanisms; and (4) Relationships of polar wind bulk parameters to solar zenith angle and to magnetospheric day-night distance, and their implications for the origin and transport of the polar wind.

Published
1998

24. Relationship of Topside Ionospheric Ion Outflows to Auroral Forms and Precipitations, Plasma Waves, and Convection Observed by POLAR

Author

Hirahara, M, Horwitz, J. L, Moore, T. E, Germany, G. A, Spann, J. F, Peterson, W. K, Shelley, E. G, Chandler, M. O, Giles, B. L, Craven, P. D, Pollock, C. J, Gurnett, D. A, Persoon, A. M, Scudder, J. D, Maynard, N. C, Mozer, F. S, Brittnacher, M. J, and Nagai, T

Subjects
Geophysics
Abstract

The POLAR satellite often observes upflowing ionospheric ions (UFls) in and near the auroral oval on southern perigee (approximately 5000 km altitude) passes. We present the UFI features observed by the thermal ion dynamics experiment (TIDE) and the toroidal imaging mass-angle spectrograph (TIMAS) in the dusk-dawn sector under two different geomagnetic activity conditions in order to elicit their relationships with auroral forms, wave emissions, and convection pattern from additional POLAR instruments. During the active interval, the ultraviolet imager (UVI) observed a bright discrete aurora on the dusk side after the substorm onset and then observed a small isolated aurora form and diffuse auroras on the dawn side during the recovery phase. The UFls showed clear conic distributions when the plasma wave instrument (PWI) detected strong broadband wave emissions below approximately 10 kHz, while no significant auroral activities were observed by UVI. At higher latitudes, the low-energy UFI conics gradually changed to the polar wind component with decreasing intensity of the broadband emissions. V-shaped auroral kilometric radiation (AKR) signatures observed above approximately 200 kHz by PWI coincided with the region where the discrete aurora and the UFI beams were detected. The latitude of these features was lower than that of the UFI conics. During the observations of the UFI beams and conics, the lower-frequency fluctuations observed by the electric field instrument (EFI) were also enhanced, and the convection directions exhibited large fluctuations. It is evident that large electrostatic potential drops produced the precipitating electrons and discrete auroras, the UFI beams, and the AKR, which is also supported by the energetic plasma data from HYDRA. Since the intense broadband emissions were also observed with the UFIs. the ionospheric ions could be energized transversely before or during the parallel acceleration due to the potential drops.

Published
1997

25. Polar Observations of Properties of H+ and O+ Conics in the Cusp Near ~5300 km Altitude

Author

Hirahara, M, Horwitz, J. L, Moore, T. E, Chandler, M. O, Giles, B. L, Craven, P. D, and Pollock, C. L

Subjects
Geophysics
Abstract

Observations by the thermal ion dynamics experiment (TIDE) on POLAR are used to explore features of low-energy ionospheric ion conical distributions at approximately 5300 km altitude over the southern cusp under different interplanetary magnetic field (IMF) conditions with negative and positive B(sub z) components. The properties are summarized as follows: (1) At the edge upstream of the convection in the cusp, the energy of outflowing ion distributions abruptly increased from a few eV to approximately 100 eV; (2) The angular distributions also abruptly changed from rammed < approximately 5 eV polar wind distributions to approximately 10-100 eV conics; (3) These conic signatures gradually gave way again to polar wind components further downstream of the cusp; (4) The uppermost energy of the detected O+ was larger than that of H+, while the density and flux of O+ were lower than those of H+; (5) The cone angles for both light and heavy ion conics were largest for the upstream region of the convection; (6) Cone angles are wider for O+ than H+; (7) The cone angles as well as the conic energies gradually decreased in the convection direction; (8) The UFI beams and conics were sometimes observed alternately, particularly for H+, and (9) In some cases, the distinct ion conic bursts occurred multiple times during a single cusp crossing.

Published
1996

31. Current Status of MPPE (Mercury Plasma Particle Experiment) on BepiColombo/MMO

Author

Saito, Y., Hirahara, M., Barabash, S., Delcourt, Dominique, André, N., Takashima, T., Asamura, K., Laboratoire de Physique des Plasmas (LPP), Université Paris-Saclay-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris-Sud - Paris 11 (UP11)-École polytechnique (X)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)

Subjects
[PHYS.PHYS.PHYS-PLASM-PH]Physics [physics]/Physics [physics]/Plasma Physics [physics.plasm-ph], Physics::Space Physics, Astrophysics::Instrumentation and Methods for Astrophysics, Astrophysics::Earth and Planetary Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

International audience; Mercury's plasma/particle environment has gradually become clear thanks to the new observations made by MESSENGER spacecraft orbiting around Mercury. However, it is also true that many questions will be left unsolved. In order to elucidate the detailed plasma structure and dynamics around Mercury, an orbiter BepiColombo MMO (Mercury Magnetospheric Orbiter) is going to be launched in 2016 as a joint mission between ESA and ISAS/JAXA. Mercury Plasma/Particle Experiment (MPPE) is a comprehensive instrument package for plasma, high-energy particle and energetic neutral atom measurements. It consists of 7 sensors: two Mercury Electron Analyzers (MEA1 and MEA2), Mercury Ion Analyzer (MIA), Mass Spectrum Analyzer (MSA), High Energy Particle instrument for electron (HEP-ele), High Energy Particle instrument for ion (HEP-ion), and Energetic Neutrals Analyzer (ENA). Currently, the MPPE sensors are on the MMO spacecraft under system integration test at ISAS/JAXA (Institute of Space and Astronautical Science / Japan Aerospace Exploration Agency). Evaluation of the sensor calibration data and the final check of the onboard processing software are being made in order to realize the flawless future plasma/particle observations around Mercury.

Published
2015

32. ERG - A small-satellite mission to investigate the dynamics of the inner magnetosphere

Author

Watanabe, S., Inner, Magnetosphere Subgroup in the Society of Geomagnetism and Earth Planetary and Space Sciences, Shiokawa, K., Seki, K., Miyoshi, Y., Ieda, A., Ono, T., Iizima, M., Nagatsuma, T., Obara, T., Takashima, Takeshi, Asamura, Kazushi, Kasaba, Yasumasa, Matsuoka, Ayako, Saito, Yoshifumi, Saito, Hirobumi, Hirahara, M., Tonegawa, Y., Toyama, F., Tanaka, M., Nose, M., Kasahara, Y., Yumoto, K., Kawano, H., Yoshikawa, A., Ebihara, Y., Yukimatsu, A., and Sato, N.

Subjects
Physics, Atmospheric Science, Range (particle radiation), Aerospace Engineering, Magnetosphere, Astronomy, Astronomy and Astrophysics, Radiation, Space weather, Particle acceleration, symbols.namesake, Geophysics, Space and Planetary Science, Van Allen radiation belt, Physics::Space Physics, symbols, General Earth and Planetary Sciences, Particle, Satellite
Abstract

著者人数：27名, Accepted: 2005-05-15, 資料番号: SA1000450000

Published
2006

33. ジオスペース探査ERGプロジェクト

Author

ERGプロジェクト, グループ, Miyoshi, Y., Ono, T., Shiokawa, K., Takashima, T., Asamura, K., Hirahara, M., Kasaba, Y., Matsuoka, A., Kojima, H., Seki, K., Fujimoto, M., and project group, ERG

Abstract

第4回極域科学シンポジウム個別セッション：[OS] 宙空圏11月15日（金） 国立極地研究所 ２階大会議室

Published
2013

34. ジオスペース探査ERGプロジェクト

Author

ERG, プロジェクトグループ, Ono, T., Miyoshi, Y., Takashima, T., Asamura, K., Hirahara, M., Kasaba, Y., Kumamoto, A., Matsuoka, A., Kojima, H., Fujimoto, M., Nagatsuma, T., and project group, ERG

Abstract

第3回極域科学シンポジウム/第36回極域宙空圏シンポジウム 11月26日（月）、27日（火） 国立極地研究所 2階ラウンジ

Published
2012

36. Small and meso-scale properties of a substorm onset auroral arc

Author

Frey, H. U., Amm, O., Chaston, C. C., Fu, S., Haerendel, G., Juusola, L., Karlsson, T., Lanchester, B., Nakamura, R., Ostgaard, N., Sakanoi, T., Seran, Elena, Whiter, D., Weygand, J., Asamura, K., Hirahara, M., Space Sciences Laboratory [Berkeley] (SSL), University of California [Berkeley], University of California-University of California, Finnish Meteorological Institute (FMI), School of Earth and Space Sciences [Hefei], University of Science and Technology of China [Hefei] (USTC), Max-Planck-Institut für Extraterrestrische Physik (MPE), Department of Physics and Technology [Bergen] (UiB), University of Bergen (UiB), Department of Space and Plasma Physics [Stockholm], KTH School of Electrical Engineering, Royal Institute of Technology [Stockholm] (KTH )-Royal Institute of Technology [Stockholm] (KTH ), School of Physics and Astronomy [Southampton], University of Southampton, Space Research Institute of Austrian Academy of Sciences (IWF), Austrian Academy of Sciences (OeAW), Planetary Plasma and Atmospheric Research Center [Sendai] (PPARC), Tohoku University [Sendai], HELIOS - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Institute of Geophysics and Planetary Physics [Los Angeles] (IGPP), University of California [Los Angeles] (UCLA), Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency [Sagamihara] (JAXA), Department of Earth and Planetary Science [Tokyo], Graduate School of Science [Tokyo], The University of Tokyo (UTokyo)-The University of Tokyo (UTokyo), The University of Tokyo (UTokyo), University of California [Berkeley] (UC Berkeley), and University of California (UC)-University of California (UC)

Subjects
[PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], Aurora, Physics::Space Physics, Small-scale
Abstract

International audience; We present small and meso-scale properties of a substorm onset arc observed simultaneously by the Reimei and THEMIS satellites together with ground-based observations by the THEMIS GBO system. The optical observations revealed the slow equatorward motion of the growth-phase arc and the development of a much brighter onset arc poleward of it. Both arcs showed the typical particle signature of electrostatic acceleration in an inverted-V structure together with a strong Alfvén wave acceleration signature at the poleward edge of the onset arc. Two THEMIS spacecraft encountered earthward flow bursts around the times the expanding optical aurora reached their magnetic footprints in the ionosphere. The particle and field measurements allowed for the reconstruction of the field-aligned current system and the determination of plasma properties in the auroral source region. Auroral arc properties were extracted from the optical and particle measurements and were used to compare measured values to theoretical predictions of the electrodynamic model for the generation of auroral arcs. Good agreement could be reached for the meso-scale arc properties. A qualitative analysis of the internal structuring of the bright onset arc suggests the operation of the tearing instability which provides a 'rope-like' appearance due to advection of the current in the sheared flow across the arc. We also note that for the observed parameters ionospheric conductivity gradients due to electron precipitation will be unstable to the feedback instability in the ionospheric Alfvén resonator that can drive structuring in luminosity over the range of scales observed.

Published
2010
Full Text
View/download PDF

39. Proposal of low energy particle observation by Mercury Magnetospheric Orbiter

Author

Saito, Y., Hirahara, M., Takashima, T., Asamura, K., Sauvaud, J.-A., Delcourt, Dominique, Coates, A., Team, Mppc, Centre d'étude des environnements terrestre et planétaires (CETP), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), and Cardon, Catherine

Subjects
[PHYS.ASTR.CO]Physics [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO], [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], [PHYS.ASTR.CO] Physics [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO], [PHYS.PHYS.PHYS-PLASM-PH]Physics [physics]/Physics [physics]/Plasma Physics [physics.plasm-ph], [PHYS.PHYS.PHYS-PLASM-PH] Physics [physics]/Physics [physics]/Plasma Physics [physics.plasm-ph], [SDU.ASTR] Sciences of the Universe [physics]/Astrophysics [astro-ph]
Published
2004

40. A mild hand cleanser, alkyl ether sulphate supplemented with alkyl ether carboxylic acid and alkyl glucoside, improves eczema on the hand and prevents the growth of Staphylococcus aureus on the skin surface.

Author

Fukui, S., Morikawa, T., Hirahara, M., Terada, Y., Shimizu, M., Takeuchi, K., and Takagi, Y.

Subjects
CLEANING compounds, ALKYL ethers, CARBOXYLIC acids, SKIN care, STAPHYLOCOCCUS aureus
Abstract

Copyright of International Journal of Cosmetic Science is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Published
2016
Full Text
View/download PDF

42. Next-Generation Plasma Particle Measurements in the Medium Energy Range: Development of Cusp Type Electrostatic Analyser and Ion Mass Spectrometer.

Author

Kasahara, S., Asamura, K., Takashima, T., Hirahara, M., Ogasawara, K., and Saito, Y.

Subjects
ELECTROSTATIC analyzers, PARTICLES (Nuclear physics), MASS spectrometers, PLASMA gases, SPECTROMETERS
Abstract

In regions such as the reconnection sites and the ring current, plasmas are highly accelerated and their energies sometimes exceed the uppermost energy level of low-energy plasma sensors (typically ∼40 keV). In order to study acceleration mechanisms in such key regions, in-situ observations with continuous energy coverage from low (∼ eV) to medium (∼10–∼200 keV) or to even higher energies are necessary. In fact, ERG and Cross scale missions are planned to explore the above regions with plasma instrument packages that require covering the majority of the energy range. We, therefore, develop a medium energy ion mass spectrometer, which consists of an Electrostatic Analyser (ESA), a Time-of-Flight mass spectrometer (ToF), and solid-state detectors (SSDs). It can simultaneously and independently measure energy-per-charge (E/q), velocity (v), and energy (E) of incoming ions, thus deducing E, m, and q. In addition, the coincidence method via the combination of ToF start-stop signals and SSD signals is useful to reject background noise that is caused by radiation belt electrons and/or solar energetic protons. In order to enable electrostatic analyses with a practical sensor size, we have developed a novel “cusp type” electrostatic analyser. This design provides us a relatively small instrument that has an energy range up to ∼200 keV/q with a full solid angle coverage (using the spacecraft spin motion). This kind of electrostatic analyser may also be used for electron measurements. [ABSTRACT FROM AUTHOR]

Published
2009
Full Text
View/download PDF

43. ARGO Science Mission.

Author

Cheng, C. Z., Chen, A., Hau, L. N., Hirahara, M., Lin, C. H., and Yau, A. W.

Subjects
ARTIFICIAL satellites, ELECTROMAGNETIC waves, SPECTROMETERS, PARTICLES (Nuclear physics)
Abstract

Taiwan’s National Space Organization (NSPO) plans to launch a series of scientific satellites during the next 15 years and will actively pursue international collaboration on scientific satellite missions. The next NSPO satellite mission is based on a LEO satellite concept, ARGO, which has a sun-synchronous orbit of 97.9 degree inclination and ∼620 km altitude, and is planned for launch in 2011. Besides carrying a remote sensing camera for earth observation, ARGO will have four space science instruments to carry out the science mission of studying ionospheric physics related to space weather with emphasis on magnetosphere-ionosphere- thermosphere coupling physics, space weather monitoring, and particle and electromagnetic wave phenomena. These four instruments are: a flux gate magnetometer (MFI), an Auroral Electron Spectrometer (AES) with energy coverage from ∼12 eV to ∼18 keV, an Imaging and Rapid-scanning ion Mass spectrometer (IRM) with energy coverage from ∼0.5 to ∼70 eV, and an Atmospheric Neutral Analyzer (ANA) which covers 0.1–2 km/s neutral velocity range. These instruments will have high time resolution and good pitch angle coverage. The science instrument operation will be open for coordinated observation campaigns with other satellite missions (FORMOSAT-2, Reimei, THEMIS, Cassiope, QuickSat, etc.) and ground-based observations. [ABSTRACT FROM AUTHOR]

Published
2009
Full Text
View/download PDF

45. Significance of Wave-Particle Interaction Analyzer for direct measurements of nonlinear wave-particle interactions.

Author

Katoh, Y., Kitahara, M., Kojima, H., Omura, Y., Kasahara, S., Hirahara, M., Miyoshi, Y., Seki, K., Asamura, K., Takashima, T., and Ono, T.

Subjects
WAVE-particle interactions, NONLINEAR wave equations, MAGNETOSPHERIC physics, PLASMA waves, MAGNETIC analyzers (Nuclear physics), ELECTRONS
Abstract

In the upcoming JAXA/ERG satellite mission, Wave Particle Interaction Analyzer (WPIA) will be installed as an onboard software function. We study the statistical significance of the WPIA for measurement of the energy transfer process between energetic electrons and whistler-mode chorus emissions in the Earth's inner magnetosphere. The WPIA measures a relative phase angle between the wave vector E and velocity vector v of each electron and computes their inner product W, where W is the time variation of the kinetic energy of energetic electrons interacting with plasma waves. We evaluate the feasibility by applying the WPIA analysis to the simulation results of whistler-mode chorus generation. We compute W using both a wave electric field vector observed at a fixed point in the simulation system and a velocity vector of each energetic electron passing through this point. By summing up Wi of an individual particle i to give Wint, we obtain significant values of Wint as expected from the evolution of chorus emissions in the simulation result.We can discuss the efficiency of the energy exchange through wave-particle interactions by selecting the range of the kinetic energy and pitch angle of the electrons used in the computation of Wint. The statistical significance of the obtained Wint is evaluated by calculating the standard deviation σW of Wint. In the results of the analysis, positive or negative Wint is obtained at the different regions of velocity phase space, while at the specific regions the obtained Wint values are significantly greater than σW, indicating efficient wave-particle interactions. The present study demonstrates the feasibility of using the WPIA, which will be on board the upcoming ERG satellite, for direct measurement of wave-particle interactions. [ABSTRACT FROM AUTHOR]

Published
2013
Full Text
View/download PDF

46. Spatial characteristics of wave-like structures in diffuse aurora obtained using optical observations.

Author

Axelsson, K., Sergienko, T., Nilsson, H., Brändström, U., Ebihara, Y., Asamura, K., and Hirahara, M.

Subjects
AURORAS, ELECTRON precipitation, MAGNETOSPHERE, PROTONS, CONVECTION (Meteorology), ATMOSPHERIC circulation, AURORAL electrons
Abstract

We present the results of a statistical study using optical images from ALIS (Auroral Large Imaging System) to investigate the spatial and temporal variations of structures in diffuse aurora. Analysis of conjugate Reimei data shows that such fine structures are a result of modulation of highenergy precipitating electrons. Pitch angle diffusion into the loss cone due to interaction of whistler mode waves with plasma sheet electrons is the most feasible mechanism leading to high-energy electron precipitation. This suggests that the fine structure is an indication of modulations of the efficiency of the wave-particle interaction. The scale sizes and variations of these structures, mapped to the magnetosphere, can give us information about the characteristics of the modulating wave activity. We found the scale size of the auroral stripes and the spacing between them to be on average 13- 14 km, which corresponds to 3-4 ion gyro radii for protons with an energy of 7 keV. The structures move southward with a speed close to zero in the plasma convection frame. [ABSTRACT FROM AUTHOR]

Published
2012
Full Text
View/download PDF

49. Ground-based observations of diffuse auroral structures in conjunction with Reimei measurements.

Author

Samara, M., Michell, R. G., Asamura, K., Hirahara, M., Hampton, D. L., and H. C. Stenbaek-Nielsen

Subjects
AURORAS, IONOSPHERE, ELECTRON precipitation, ARTIFICIAL satellites, PARTICLES (Nuclear physics), UNSTEADY flow
Abstract

We present results from ground-based auroral observations coordinated with the Japanese satellite, Reimei, that took place during the winters of 2006, 2007 and 2008 at Poker Flat, Alaska. Comparable temporal and spatial resolution for the optical and in situ particle data, allowed for investigation of small scale and/or rapidly time-varying auroral structures. Four satellite passes through diffuse auroral structures were identified. The structures within the aurora, whether stationary or time-varying (pulsating aurora), were most closely correlated with the highest energy precipitating electrons measured by these detectors (8 to 12 keV). This relation is found to be consistent across all four examples, revealing that the electron precipitation responsible for these diffuse auroral structures is primarily that of the ⩾8 keV electrons. [ABSTRACT FROM AUTHOR]

Published
2010
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results