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  • 1.
    Gingell, Imogen
    et al.
    Imperial Coll London, Blackett Lab, London, England..
    Schwartz, Steven J.
    Imperial Coll London, Blackett Lab, London, England..
    Burgess, David
    Queen Mary Univ London, Sch Phys & Astron, London, England..
    Johlander, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Russell, Christopher T.
    Univ Calif Los Angeles, Dept Earth & Planetary Sci Phys, Los Angeles, CA USA..
    Burch, James L.
    Southwest Res Inst, San Antonio, TX USA..
    Ergun, Robert E.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80309 USA..
    Fuselier, Stephen
    Southwest Res Inst, San Antonio, TX USA.;Univ Texas San Antonio, Dept Phys & Astron, San Antonio, TX USA..
    Gershman, Daniel J.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Giles, Barbara L.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Goodrich, Katherine A.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80309 USA..
    Khotyaintsev, Yuri V.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Lavraud, Benoit
    Univ Toulouse, Inst Rech Astrophys & Planetol, Toulouse, France..
    Lindqvist, Per-Arne
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Strangeway, Robert J.
    Univ Calif Los Angeles, Dept Earth & Planetary Sci Phys, Los Angeles, CA USA..
    Trattner, Karlheinz
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80309 USA..
    Torbert, Roy B.
    Univ New Hampshire, Phys Dept, Durham, NH 03824 USA..
    Wei, Hanying
    Univ Calif Los Angeles, Dept Earth & Planetary Sci Phys, Los Angeles, CA USA..
    Wilder, Frederick
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80309 USA..
    MMS Observations and Hybrid Simulations of Surface Ripples at a Marginally Quasi-Parallel Shock2017In: Journal of Geophysical Research - Space Physics, ISSN 2169-9380, E-ISSN 2169-9402, Vol. 122, no 11, p. 11003-11017Article in journal (Refereed)
    Abstract [en]

    Simulations and observations of collisionless shocks have shown that deviations of the nominal local shock normal orientation, that is, surface waves or ripples, are expected to propagate in the ramp and overshoot of quasi-perpendicular shocks. Here we identify signatures of a surface ripple propagating during a crossing of Earth's marginally quasi-parallel (theta(Bn) similar to 45 degrees) or quasi-parallel bow shock on 27 November 2015 06: 01: 44 UTC by the Magnetospheric Multiscale (MMS) mission and determine the ripple's properties using multispacecraft methods. Using two-dimensional hybrid simulations, we confirm that surface ripples are a feature of marginally quasi-parallel and quasi-parallel shocks under the observed solar wind conditions. In addition, since these marginally quasi-parallel and quasi-parallel shocks are expected to undergo a cyclic reformation of the shock front, we discuss the impact of multiple sources of nonstationarity on shock structure. Importantly, ripples are shown to be transient phenomena, developing faster than an ion gyroperiod and only during the period of the reformation cycle when a newly developed shock ramp is unaffected by turbulence in the foot. We conclude that the change in properties of the ripple observed by MMS is consistent with the reformation of the shock front over a time scale of an ion gyroperiod.

  • 2.
    Goodrich, Katherine A.
    et al.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80309 USA.
    Ergun, Robert
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80309 USA.
    Schwartz, Steven J.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80309 USA.
    Wilson, Lynn B., III
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA.
    Newman, David
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80309 USA.
    Wilder, Frederick D.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80309 USA.
    Holmes, Justin
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80309 USA.
    Johlander, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Burch, James
    Southwest Res Inst, San Antonio, TX USA.
    Torbert, Roy
    Univ New Hampshire, Inst Study Earth Oceans & Space, Durham, NH 03824 USA.
    Khotyaintsev, Yuri V.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Lindqvist, Per-Arne
    KTH Royal Inst Technol, Dept Space & Plasma Phys, Stockholm, Sweden.
    Strangeway, Robert
    Univ Calif Los Angeles, Inst Geophys & Planetary Phys, Los Angeles, CA 90024 USA.
    Russell, Christopher
    Univ Calif Los Angeles, Inst Geophys & Planetary Phys, Los Angeles, CA 90024 USA.
    Gershman, Daniel
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA.
    Giles, Barbara
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA.
    Andersson, Laila
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80309 USA.
    MMS Observations of Electrostatic Waves in an Oblique Shock Crossing2018In: Journal of Geophysical Research - Space Physics, ISSN 2169-9380, E-ISSN 2169-9402, Vol. 123, no 11, p. 9430-9442Article in journal (Refereed)
    Abstract [en]

    High-resolution particle and wave measurements taken during an oblique bow shock crossing by the Magnetospheric Multiscale (MMS) mission are analyzed. Two regions of differing magnetic behavior are identified within the shock, one with active magnetic fluctuations and one with laminar interplanetary magnetic field topology. A prominent reflected ion population is observed in both regions. The active magnetic region is characterized by large-amplitude (>100 mV/m) electrostatic solitary waves, electron Bernstein waves, and ion acoustic waves, along with intermittent current activity and localized electron heating. In the region of laminar magnetic field, ion acoustic waves are prominently observed. Solar wind ion deceleration is observed in both regions of active and laminar magnetic field. All observations suggest that solar wind deceleration can occur as a result of multiple independent processes, in this case current and ion-ion instabilities.

  • 3.
    Johlander, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Ion dynamics and structure of collisionless shocks2016Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Shock waves are responsible for slowing down and heating supersonic flows. In collisionless space plasmas, shocks are able to accelerate particles to very high energies. We study injection of suprathermal ions at Earth’s quasi- parallel shock using high time resolution data from the Cluster spacecraft. We find that solar wind ions reflect off short large-amplitude magnetic structures (SLAMSs) and are subsequently accelerated by the convection electric field. We also use data from the closely-spaced Magnetospheric MultiScale (MMS) spacecraft to compare competing non-stationarity processes at Earth’s quasi- perpendicular bow shock. Using MMS’s high cadence plasma measurements, we find that the shock exhibits non-stationarity in the form of ripples.

  • 4.
    Johlander, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Space Plasma Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Ion dynamics and structure of collisionless shocks in space2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Shock waves form when supersonic flows encounter an obstacle. Like in regular gases, shock waves can form in a plasma - a gas of electrically charged particles. Shock waves in plasmas where collisions between particles are very rare are referred to as collisionless shock waves. Collisionless shocks are some of the most energetic plasma phenomena in the universe. They are found for example around exploded supernova remnants and in our solar system where the supersonic solar wind encounters obstacles like planets and the interstellar medium. Shock waves in plasmas are very efficient particle accelerators though a process known as diffusive shock acceleration. An example of particles accelerated in shock waves are the extremely energetic galactic cosmic rays that permeate the galaxy. This thesis addresses the physics of collisionless shocks using spacecraft observations of the Earth's bow shock, particularly understanding the ion dynamics and shock structure for different shock conditions. For this we have used data from ESA's four Cluster satellites and NASA's four Magnetospheric Multiscale (MMS) satellites. The first study presents Cluster measurements from the quasi-parallel bow shock, where the angle between the magnetic field and the shock normal is less than 45 degrees. We study the first steps of acceleration of solar wind ions at short large-amplitude magnetic structures (SLAMS). We observe nearly specularly reflected solar wind ions upstream of a SLAMS. By gyration in the solar wind, the reflected ions are accelerated to a few times the solar wind energy. The second and third study are about shock non-stationarity using MMS measurements from the quasi-perpendicular shock, where the angle between the magnetic field and the shock normal is greater than 45 degrees. In the second study we show that the shock is non-stationary in the form of ripples that propagate along the shock surface. In the third study we study closer in detail the dispersive properties of the ripples and find that whether a solar wind ion will be reflected at the shock is dependent on where it impinges on the rippled shock. In the fourth study we quantify the conditions for ion acceleration shocks by using MMS measurements from many encounters with the bow shock. We find that the quasi-parallel shock is efficient with up to 10% of the energy density in energetic ions. We also find that at quasi-parallel shocks, SLAMS can restrict high-energy ions from propagating upstream and convect them back to the shock, potentially increasing acceleration efficiency.

  • 5.
    Johlander, Andreas
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Space Plasma Physics.
    Schwartz, S .J.
    Imperial Coll London, Blackett Lab, London SW7 2AZ, England; Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80303 USA.
    Vaivads, Andris
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Khotyaintsev, Yuri V.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Gingell, I.
    Blackett Laboratory, Imperial College London, London SW7 2AZ, United Kingdom.
    Peng, I. B.
    KTH Royal Institute of Technology, Stockholm 11428, Sweden.
    Markidis, S.
    KTH Royal Institute of Technology, Stockholm 11428, Sweden.
    Lindqvist, P-A.
    KTH Royal Institute of Technology, Stockholm 11428, Sweden.
    Ergun, R. E.
    Laboratory of Atmospheric and Space Physics, University of Colorado, Boulder, Colorado 80303, USA.
    Marklund, G. T.
    KTH Royal Institute of Technology, Stockholm 11428, Sweden.
    Plaschke, F.
    Space Research Institute, Austrian Academy of Sciences, Graz 8042, Austria.
    Magnes, W.
    Space Research Institute, Austrian Academy of Sciences, Graz 8042, Austria.
    Strangeway, R. J.
    University of California, Los Angeles, California 90095, USA.
    Russell, C.T.
    University of California, Los Angeles, California 90095, USA.
    Wei, H.
    University of California, Los Angeles, California 90095, USA.
    Torbert, R. B.
    University of New Hampshire, Durham, New Hampshire 03824, USA.
    Paterson, W. R.
    NASA Goddard Space Flight Center, Greenbelt, Maryland 20771, USA.
    Gershman, D. J.
    NASA Goddard Space Flight Center, Greenbelt, Maryland 20771, USA; University of Maryland, College Park, Maryland 20742, USA.
    Dorelli, J. C.
    NASA Goddard Space Flight Center, Greenbelt, Maryland 20771, USA.
    Avanov, L. A.
    NASA Goddard Space Flight Center, Greenbelt, Maryland 20771, USA.
    Lavraud, B.
    Institut de Recherche en Astrophysique et Planétologie, Université de Toulouse, Toulouse 31028, France; Centre National de la Recherche Scientifique, UMR 5277, Toulouse 31400, France.
    Saito, Y.
    Institute of Space and Astronautical Science, JAXA, Sagamihara 2525210, Japan.
    Giles, B. L.
    NASA Goddard Space Flight Center, Greenbelt, Maryland 20771, USA.
    Pollock, C. J.
    NASA Goddard Space Flight Center, Greenbelt, Maryland 20771, USA.
    Burch, J. L.
    Southwest Research Institute, San Antonio, Texas 78238, USA.
    Rippled quasiperpendicularshock observed by the Magnetospheric Multiscale spacecraft2016In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 117, no 16, article id 165101Article in journal (Refereed)
    Abstract [en]

    Collisionless shock non-stationarity arising from micro-scale physics influences shock structure and particle acceleration mechanisms. Non-stationarity has been difficult to quantify due to the small spatial and temporal scales. We use the closely-spaced (sub-gyroscale), high time-resolution measurements from one rapid crossing of Earth's quasi-perpendicular bow shock by the Magnetospheric Multiscale (MMS) spacecraft to compare competing non-stationarity processes. Using MMS's high cadence kinetic plasma measurements, we show that the shock exhibits non-stationarity in the form of ripples.

  • 6.
    Johlander, Andreas
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Space Plasma Physics.
    Vaivads, Andris
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Khotyaintsev, Yuri V.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Caprioli, Damiano
    Department of Astronomy and Astrophysics, University of Chicago, Chicago, IL, USA.
    Haggerty, Colby C.
    Department of Astronomy and Astrophysics, University of Chicago, Chicago, IL, USA.
    Schwartz, Steven J.
    Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO, US.
    Conditions for ion acclereration at collisionless shocksManuscript (preprint) (Other academic)
  • 7.
    Johlander, Andreas
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Vaivads, Andris
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Khotyaintsev, Yuri V.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Gingell, Imogen
    Schwartz, Steven J
    Giles, Barbara L
    Torbert, Roy B
    Russell, Christopher T
    Shock ripples observed by the MMS spacecraft: ion reflection and dispersive properties2018In: Plasma Physics and Controlled Fusion, ISSN 0741-3335, E-ISSN 1361-6587, Vol. 60, article id 125006Article in journal (Refereed)
    Abstract [en]

    Shock ripples are ion-inertial-scale waves propagating within the front region of magnetized quasi-perpendicular collisionless shocks. The ripples are thought to influence particle dynamics and acceleration at shocks. With the four magnetospheric multiscale (MMS) spacecraft, it is for the first time possible to fully resolve the small scale ripples in space. We use observations of one slow crossing of the Earth’s non-stationary bow shock by MMS. From multi-spacecraft measurements we show that the non-stationarity is due to ripples propagating along the shock surface. We find that the ripples are near linearly polarized waves propagating in the coplanarity plane with a phase speed equal to the local Alfvén speed and have a wavelength close to 5 times the upstream ion inertial length. The dispersive properties of the ripples resemble those of Alfvén ion cyclotron waves in linear theory. Taking advantage of the slow crossing by the four MMS spacecraft, we map the shock-reflected ions as a function of ripple phase and distance from the shock. We find that ions are preferentially reflected in regions of the wave with magnetic field stronger than the average overshoot field, while in the regions of lower magnetic field, ions penetrate the shock to the downstream region.

  • 8.
    Johlander, Andreas
    et al.
    Uppsala universitet, Institutet för rymdfysik, Uppsalaavdelningen.
    Vaivads, Andris
    Uppsala universitet, Institutet för rymdfysik, Uppsalaavdelningen.
    Khotyaintsev, Yuri V.
    Uppsala universitet, Institutet för rymdfysik, Uppsalaavdelningen.
    Gingell, Imogen
    Schwartz, Steven J
    Giles, Barbara L
    Torbert, Roy B
    Russell, Christopher T
    Shock ripples observed by the MMS spacecraft: ion reflection and dispersive properties2018In: Plasma Physics and Controlled Fusion, ISSN 0741-3335, E-ISSN 1361-6587, Vol. 60, article id 125006Article in journal (Refereed)
    Abstract [en]

    Shock ripples are ion-inertial-scale waves propagating within the front region of magnetized quasi-perpendicular collisionless shocks. The ripples are thought to influence particle dynamics and acceleration at shocks. With the four magnetospheric multiscale (MMS) spacecraft, it is for the first time possible to fully resolve the small scale ripples in space. We use observations of one slow crossing of the Earth’s non-stationary bow shock by MMS. From multi-spacecraft measurements we show that the non-stationarity is due to ripples propagating along the shock surface. We find that the ripples are near linearly polarized waves propagating in the coplanarity plane with a phase speed equal to the local Alfvén speed and have a wavelength close to 5 times the upstream ion inertial length. The dispersive properties of the ripples resemble those of Alfvén ion cyclotron waves in linear theory. Taking advantage of the slow crossing by the four MMS spacecraft, we map the shock-reflected ions as a function of ripple phase and distance from the shock. We find that ions are preferentially reflected in regions of the wave with magnetic field stronger than the average overshoot field, while in the regions of lower magnetic field, ions penetrate the shock to the downstream region.

  • 9.
    Johlander, Andreas
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Space Plasma Physics. UPMC, Ecole Polytech, CNRS, Lab Phys Plasmas, Palaiseau, France..
    Vaivads, Andris
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Space Plasma Physics.
    Khotyaintsev, Yuri V.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Retinò, A.
    Dandouras, I.
    Univ Toulouse 3, F-31062 Toulouse, France.;CNRS, IRAP, Toulouse, France..
    Ion Injection At Quasi-Parallel Shocks Seen By The Cluster Spacecraft2016In: Astrophysical Journal Letters, ISSN 2041-8205, E-ISSN 2041-8213, Vol. 817, no 1, article id L4Article in journal (Refereed)
    Abstract [en]

    Collisionless shocks in space plasma are known to be capable of accelerating ions to very high energies through diffusive shock acceleration (DSA). This process requires an injection of suprathermal ions, but the mechanisms producing such a suprathermal ion seed population are still not fully understood. We study acceleration of solar wind ions resulting from reflection off short large-amplitude magnetic structures (SLAMSs) in the quasi-parallel bow shock of Earth using in situ data from the four Cluster spacecraft. Nearly specularly reflected solar wind ions are observed just upstream of a SLAMS. The reflected ions are undergoing shock drift acceleration (SDA) and obtain energies higher than the solar wind energy upstream of the SLAMS. Our test particle simulations show that solar wind ions with lower energy are more likely to be reflected off the SLAMS, while high-energy ions pass through the SLAMS, which is consistent with the observations. The process of SDA at SLAMSs can provide an effective way of accelerating solar wind ions to suprathermal energies. Therefore, this could be a mechanism of ion injection into DSA in astrophysical plasmas.

  • 10.
    Johlander, Andreas
    et al.
    Uppsala universitet, Institutet för rymdfysik, Uppsalaavdelningen.
    Vaivads, Andris
    Uppsala universitet, Institutet för rymdfysik, Uppsalaavdelningen.
    Khotyaintsev, Yuri V.
    Uppsala universitet, Institutet för rymdfysik, Uppsalaavdelningen.
    Retinò, A.
    Dandouras, I.
    Univ Toulouse 3, F-31062 Toulouse, France.;CNRS, IRAP, Toulouse, France..
    Ion Injection At Quasi-Parallel Shocks Seen By The Cluster Spacecraft2016In: Astrophysical Journal Letters, ISSN 2041-8205, E-ISSN 2041-8213, Vol. 817, no 1, article id L4Article in journal (Refereed)
    Abstract [en]

    Collisionless shocks in space plasma are known to be capable of accelerating ions to very high energies through diffusive shock acceleration (DSA). This process requires an injection of suprathermal ions, but the mechanisms producing such a suprathermal ion seed population are still not fully understood. We study acceleration of solar wind ions resulting from reflection off short large-amplitude magnetic structures (SLAMSs) in the quasi-parallel bow shock of Earth using in situ data from the four Cluster spacecraft. Nearly specularly reflected solar wind ions are observed just upstream of a SLAMS. The reflected ions are undergoing shock drift acceleration (SDA) and obtain energies higher than the solar wind energy upstream of the SLAMS. Our test particle simulations show that solar wind ions with lower energy are more likely to be reflected off the SLAMS, while high-energy ions pass through the SLAMS, which is consistent with the observations. The process of SDA at SLAMSs can provide an effective way of accelerating solar wind ions to suprathermal energies. Therefore, this could be a mechanism of ion injection into DSA in astrophysical plasmas.

  • 11.
    Khotyaintsev, Yuri V.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Graham, D. B.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Norgren, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Space Plasma Physics.
    Eriksson, Elin
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Space Plasma Physics.
    Li, Wenya
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Johlander, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Vaivads, Andris
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Andre, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Pritchett, P. L.
    Univ Calif Los Angeles, Dept Phys & Astron, Los Angeles, CA USA..
    Retino, A.
    CNRS, LPP, Palaiseau, France..
    Phan, T. D.
    Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA..
    Ergun, R. E.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80309 USA..
    Goodrich, K.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80309 USA..
    Lindqvist, P. -A
    Marklund, G. T.
    KTH Royal Inst Technol, Stockholm, Sweden..
    Le Contel, O.
    CNRS, LPP, Palaiseau, France..
    Plaschke, F.
    Austrian Acad Sci, Space Res Inst, Graz, Austria..
    Magnes, W.
    Austrian Acad Sci, Space Res Inst, Graz, Austria..
    Strangeway, R. J.
    Univ Calif Los Angeles, Dept Earth & Space Sci, Los Angeles, CA 90024 USA..
    Russell, C. T.
    Univ Calif Los Angeles, Dept Earth & Space Sci, Los Angeles, CA 90024 USA..
    Vaith, H.
    Univ New Hampshire, Ctr Space Sci, Durham, NH 03824 USA..
    Argall, M. R.
    Univ New Hampshire, Ctr Space Sci, Durham, NH 03824 USA..
    Kletzing, C. A.
    Univ Iowa, Dept Phys & Astron, Iowa City, IA 52242 USA..
    Nakamura, R.
    Austrian Acad Sci, Space Res Inst, Graz, Austria..
    Torbert, R. B.
    Univ New Hampshire, Ctr Space Sci, Durham, NH 03824 USA..
    Paterson, W. R.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Gershman, D. J.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA.;Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Dorelli, J. C.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Avanov, L. A.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Lavraud, B.
    CNRS, IRAP, Toulouse, France..
    Saito, Y.
    JAXA, Chofu, Tokyo, Japan..
    Giles, B. L.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Pollock, C. J.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Turner, D. L.
    Aerosp Corp, Dept Space Sci, El Segundo, CA 90245 USA..
    Blake, J. D.
    Aerosp Corp, Dept Space Sci, El Segundo, CA 90245 USA..
    Fennell, J. F.
    Aerosp Corp, Dept Space Sci, El Segundo, CA 90245 USA..
    Jaynes, A.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80309 USA..
    Mauk, B. H.
    Johns Hopkins Univ, Appl Phys Lab, Laurel, MD USA..
    Burch, J. L.
    Southwest Res Inst, San Antonio, TX USA..
    Electron jet of asymmetric reconnection2016In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 43, no 11, p. 5571-5580Article in journal (Refereed)
    Abstract [en]

    We present Magnetospheric Multiscale observations of an electron-scale current sheet and electron outflow jet for asymmetric reconnection with guide field at the subsolar magnetopause. The electron jet observed within the reconnection region has an electron Mach number of 0.35 and is associated with electron agyrotropy. The jet is unstable to an electrostatic instability which generates intense waves with E-vertical bar amplitudes reaching up to 300mVm(-1) and potentials up to 20% of the electron thermal energy. We see evidence of interaction between the waves and the electron beam, leading to quick thermalization of the beam and stabilization of the instability. The wave phase speed is comparable to the ion thermal speed, suggesting that the instability is of Buneman type, and therefore introduces electron-ion drag and leads to braking of the electron flow. Our observations demonstrate that electrostatic turbulence plays an important role in the electron-scale physics of asymmetric reconnection.

  • 12.
    Peng, Ivy Bo
    et al.
    KTH Royal Inst Technol, Stockholm, Sweden..
    Markidis, Stefano
    KTH Royal Inst Technol, Stockholm, Sweden..
    Laure, Erwin
    KTH Royal Inst Technol, Stockholm, Sweden..
    Johlander, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Vaivads, Andris
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Khotyaintsev, Yuri
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Henri, Pierre
    LPC2E CNRS, Orleans, France..
    Lapenta, Giovanni
    Katholieke Univ Leuven, Ctr Math Plasma Astrophys, Leuven, Belgium..
    Kinetic structures of quasi-perpendicular shocks in global particle-in-cell simulations2015In: Physics of Plasmas, ISSN 1070-664X, E-ISSN 1089-7674, Vol. 22, no 9, article id 092109Article in journal (Refereed)
    Abstract [en]

    We carried out global Particle-in-Cell simulations of the interaction between the solar wind and a magnetosphere to study the kinetic collisionless physics in super-critical quasi-perpendicular shocks. After an initial simulation transient, a collisionless bow shock forms as a result of the interaction of the solar wind and a planet magnetic dipole. The shock ramp has a thickness of approximately one ion skin depth and is followed by a trailing wave train in the shock downstream. At the downstream edge of the bow shock, whistler waves propagate along the magnetic field lines and the presence of electron cyclotron waves has been identified. A small part of the solar wind ion population is specularly reflected by the shock while a larger part is deflected and heated by the shock. Solar wind ions and electrons are heated in the perpendicular directions. Ions are accelerated in the perpendicular direction in the trailing wave train region. This work is an initial effort to study the electron and ion kinetic effects developed near the bow shock in a realistic magnetic field configuration.

  • 13.
    Schwartz, Steven J.
    et al.
    Imperial Coll London, London, England;Univ Colorado Boulder, Lab Atmospher & Space Phys, Boulder, CO 80309 USA.
    Avanov, Levon
    NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA.
    Turner, Drew
    Aerosp Corp, POB 92957, Los Angeles, CA 90009 USA.
    Zhang, Hui
    Univ Alaska Fairbanks, Geophys Inst, Fairbanks, AK 99775 USA.
    Gingell, Imogen
    Imperial Coll London, London, England.
    Eastwood, Jonathan P.
    Imperial Coll London, London, England.
    Gershman, Daniel J.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA.
    Johlander, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Russell, Christopher T.
    Univ Calif Los Angeles, Earth Planetary & Space Sci, Los Angeles, CA USA.
    Burch, James L.
    Southwest Res Inst, San Antonio, TX USA.
    Dorelli, John C.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA.
    Eriksson, Stefan
    Univ Colorado Boulder, Lab Atmospher & Space Phys, Boulder, CO 80309 USA.
    Ergun, Robert E.
    Univ Colorado Boulder, Lab Atmospher & Space Phys, Boulder, CO 80309 USA.
    Fuselier, Stephen A.
    Southwest Res Inst, San Antonio, TX USA;Univ Texas San Antonio, Dept Phys & Astron, San Antonio, TX USA.
    Giles, Barbara L.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA.
    Goodrich, Katherine A.
    Univ Colorado Boulder, Lab Atmospher & Space Phys, Boulder, CO 80309 USA.
    Khotyaintsev, Yuri V.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Lavraud, Benoit
    Imperial Coll London, London, England;Univ Toulouse, UPS, CNRS, Inst Rech Astrophys & Planetol,CNES, Toulouse, France.
    Lindqvist, Per-Arne
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Oka, Mitsuo
    Imperial Coll London, London, England;Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA.
    Phan, Tai-Duc
    Strangeway, Robert J.
    Univ Calif Los Angeles, Earth Planetary & Space Sci, Los Angeles, CA USA.
    Trattner, Karlheinz J.
    Univ Colorado Boulder, Lab Atmospher & Space Phys, Boulder, CO 80309 USA.
    Torbert, Roy B.
    Imperial Coll London, London, England;Univ Colorado Boulder, Lab Atmospher & Space Phys, Boulder, CO 80309 USA;Univ New Hampshire, Dept Phys, Durham, NH 03824 USA.
    Vaivads, Andris
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Wei, Hanying
    Univ Calif Los Angeles, Earth Planetary & Space Sci, Los Angeles, CA USA.
    Wilder, Frederick
    Univ Colorado Boulder, Lab Atmospher & Space Phys, Boulder, CO 80309 USA.
    Ion Kinetics in a Hot Flow Anomaly: MMS Observations2018In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 45, no 21, p. 11520-11529Article in journal (Refereed)
    Abstract [en]

    Hot Flow Anomalies (HFAs) are transients observed at planetary bow shocks, formed by the shock interaction with a convected interplanetary current sheet. The primary interpretation relies on reflected ions channeled upstream along the current sheet. The short duration of HFAs has made direct observations of this process difficult. We employ high resolution measurements by NASA's Magnetospheric Multiscale Mission to probe the ion microphysics within a HFA. Magnetospheric Multiscale Mission data reveal a smoothly varying internal density and pressure, which increase toward the trailing edge of the HFA, sweeping up particles trapped within the current sheet. We find remnants of reflected or other backstreaming ions traveling along the current sheet, but most of these are not fast enough to out-run the incident current sheet convection. Despite the high level of internal turbulence, incident and backstreaming ions appear to couple gyro-kinetically in a coherent manner. Plain Language Summary Shock waves in space are responsible for energizing particles and diverting supersonic flows around planets and other obstacles. Explosive events known as Hot Flow Anomalies (HFAs) arise when a rapid change in the interplanetary magnetic field arrives at the bow shock formed by, for example, the supersonic solar wind plasma flow from the Sun impinging on the Earth's magnetic environment. HFAs are known to produce impacts all the way to ground level, but the physics responsible for their formation occur too rapidly to be resolved by previous satellite missions. This paper employs NASA's fleet of four Magnetospheric Multiscale satellites to reveal for the first time clear, discreet populations of ions that interact coherently to produce the extreme heating and deflection.

  • 14.
    Schwartz, Steven J.
    et al.
    Imperial Coll London, London, England;Univ Colorado Boulder, Lab Atmospher & Space Phys, Boulder, CO 80309 USA.
    Avanov, Levon
    NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA.
    Turner, Drew
    Aerosp Corp, POB 92957, Los Angeles, CA 90009 USA.
    Zhang, Hui
    Univ Alaska Fairbanks, Geophys Inst, Fairbanks, AK 99775 USA.
    Gingell, Imogen
    Imperial Coll London, London, England.
    Eastwood, Jonathan P.
    Imperial Coll London, London, England.
    Gershman, Daniel J.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA.
    Johlander, Andreas
    Uppsala universitet, Institutet för rymdfysik, Uppsalaavdelningen.
    Russell, Christopher T.
    Univ Calif Los Angeles, Earth Planetary & Space Sci, Los Angeles, CA USA.
    Burch, James L.
    Southwest Res Inst, San Antonio, TX USA.
    Dorelli, John C.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA.
    Eriksson, Stefan
    Univ Colorado Boulder, Lab Atmospher & Space Phys, Boulder, CO 80309 USA.
    Ergun, Robert E.
    Univ Colorado Boulder, Lab Atmospher & Space Phys, Boulder, CO 80309 USA.
    Fuselier, Stephen A.
    Southwest Res Inst, San Antonio, TX USA;Univ Texas San Antonio, Dept Phys & Astron, San Antonio, TX USA.
    Giles, Barbara L.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA.
    Goodrich, Katherine A.
    Univ Colorado Boulder, Lab Atmospher & Space Phys, Boulder, CO 80309 USA.
    Khotyaintsev, Yuri V.
    Uppsala universitet, Institutet för rymdfysik, Uppsalaavdelningen.
    Lavraud, Benoit
    Imperial Coll London, London, England;Univ Toulouse, UPS, CNRS, Inst Rech Astrophys & Planetol,CNES, Toulouse, France.
    Lindqvist, Per-Arne
    Uppsala universitet, Institutet för rymdfysik, Uppsalaavdelningen.
    Oka, Mitsuo
    Imperial Coll London, London, England;Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA.
    Phan, Tai-Duc
    Strangeway, Robert J.
    Univ Calif Los Angeles, Earth Planetary & Space Sci, Los Angeles, CA USA.
    Trattner, Karlheinz J.
    Univ Colorado Boulder, Lab Atmospher & Space Phys, Boulder, CO 80309 USA.
    Torbert, Roy B.
    Imperial Coll London, London, England;Univ Colorado Boulder, Lab Atmospher & Space Phys, Boulder, CO 80309 USA;Univ New Hampshire, Dept Phys, Durham, NH 03824 USA.
    Vaivads, Andris
    Uppsala universitet, Institutet för rymdfysik, Uppsalaavdelningen.
    Wei, Hanying
    Univ Calif Los Angeles, Earth Planetary & Space Sci, Los Angeles, CA USA.
    Wilder, Frederick
    Univ Colorado Boulder, Lab Atmospher & Space Phys, Boulder, CO 80309 USA.
    Ion Kinetics in a Hot Flow Anomaly: MMS Observations2018In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 45, no 21, p. 11520-11529Article in journal (Refereed)
    Abstract [en]

    Hot Flow Anomalies (HFAs) are transients observed at planetary bow shocks, formed by the shock interaction with a convected interplanetary current sheet. The primary interpretation relies on reflected ions channeled upstream along the current sheet. The short duration of HFAs has made direct observations of this process difficult. We employ high resolution measurements by NASA's Magnetospheric Multiscale Mission to probe the ion microphysics within a HFA. Magnetospheric Multiscale Mission data reveal a smoothly varying internal density and pressure, which increase toward the trailing edge of the HFA, sweeping up particles trapped within the current sheet. We find remnants of reflected or other backstreaming ions traveling along the current sheet, but most of these are not fast enough to out-run the incident current sheet convection. Despite the high level of internal turbulence, incident and backstreaming ions appear to couple gyro-kinetically in a coherent manner. Plain Language Summary Shock waves in space are responsible for energizing particles and diverting supersonic flows around planets and other obstacles. Explosive events known as Hot Flow Anomalies (HFAs) arise when a rapid change in the interplanetary magnetic field arrives at the bow shock formed by, for example, the supersonic solar wind plasma flow from the Sun impinging on the Earth's magnetic environment. HFAs are known to produce impacts all the way to ground level, but the physics responsible for their formation occur too rapidly to be resolved by previous satellite missions. This paper employs NASA's fleet of four Magnetospheric Multiscale satellites to reveal for the first time clear, discreet populations of ions that interact coherently to produce the extreme heating and deflection.

1 - 14 of 14
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