Simulations of pickup ion mediated quasi-perpendicular shocks: Implications for the heliospheric termination shock

Shuichi Matsukiyo, Manfred Scholer

    Research output: Contribution to journalArticle

    11 Citations (Scopus)

    Abstract

    The microstructure of the heliospheric termination shock and the accompanied local acceleration processes of both ions and electrons are investigated by utilizing one-dimensional full particle-in-cell simulations for a variety of parameters. The relative pickup ion density is assumed to be 20-30%. The magnetic field and the shock potential profiles exhibit significant differences, since the former mostly reflects the dynamics of solar wind ions, whereas the latter is mainly sustained by the bulk motion of the reflected pickup ions in the extended foot. The discrepancy between the magnetic field profile and the potential profile increases with Alfvén Mach number. Most of the downstream thermal energy is gained by the pickup ions, while some heating of the solar wind ions and electrons occurs through the modified two-stream instability excited in the extended foot. Self-reformation can occur when the relative pickup ion density is 20% but is blurred when it becomes as large as 30%. Reformation is also suppressed if the local solar wind ion temperature in the extended foot is high, which can either be due to heating by the modified two-stream instability or is already determined by the solar wind temperature far upstream. In all runs presented in this study no evidence for shock surfing acceleration of pickup ions could be found. Nonthermal particle acceleration occurs for oblique shocks. Electron (pickup ion) shock drift acceleration is evidenced when the shock angle is below 80° (60°). Key Points Parameter dependences of microstructures of the termination shock are examined Profiles of magnetic field and potential show significant differences Shock drift acceleration mechanism works for both electrons and pickup ions

    Original languageEnglish
    Pages (from-to)2388-2399
    Number of pages12
    JournalJournal of Geophysical Research: Space Physics
    Volume119
    Issue number4
    DOIs
    Publication statusPublished - Jan 1 2014

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    Pickups
    shock
    Ions
    ions
    ion
    sensors
    solar wind
    simulation
    Solar wind
    magnetic fields
    electrons
    profiles
    electron
    Electrons
    Magnetic fields
    magnetic field
    heat
    microstructure
    heating
    particle acceleration

    All Science Journal Classification (ASJC) codes

    • Geophysics
    • Forestry
    • Oceanography
    • Aquatic Science
    • Ecology
    • Water Science and Technology
    • Soil Science
    • Geochemistry and Petrology
    • Earth-Surface Processes
    • Atmospheric Science
    • Earth and Planetary Sciences (miscellaneous)
    • Space and Planetary Science
    • Palaeontology

    Cite this

    Simulations of pickup ion mediated quasi-perpendicular shocks : Implications for the heliospheric termination shock. / Matsukiyo, Shuichi; Scholer, Manfred.

    In: Journal of Geophysical Research: Space Physics, Vol. 119, No. 4, 01.01.2014, p. 2388-2399.

    Research output: Contribution to journalArticle

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    abstract = "The microstructure of the heliospheric termination shock and the accompanied local acceleration processes of both ions and electrons are investigated by utilizing one-dimensional full particle-in-cell simulations for a variety of parameters. The relative pickup ion density is assumed to be 20-30{\%}. The magnetic field and the shock potential profiles exhibit significant differences, since the former mostly reflects the dynamics of solar wind ions, whereas the latter is mainly sustained by the bulk motion of the reflected pickup ions in the extended foot. The discrepancy between the magnetic field profile and the potential profile increases with Alfv{\'e}n Mach number. Most of the downstream thermal energy is gained by the pickup ions, while some heating of the solar wind ions and electrons occurs through the modified two-stream instability excited in the extended foot. Self-reformation can occur when the relative pickup ion density is 20{\%} but is blurred when it becomes as large as 30{\%}. Reformation is also suppressed if the local solar wind ion temperature in the extended foot is high, which can either be due to heating by the modified two-stream instability or is already determined by the solar wind temperature far upstream. In all runs presented in this study no evidence for shock surfing acceleration of pickup ions could be found. Nonthermal particle acceleration occurs for oblique shocks. Electron (pickup ion) shock drift acceleration is evidenced when the shock angle is below 80° (60°). Key Points Parameter dependences of microstructures of the termination shock are examined Profiles of magnetic field and potential show significant differences Shock drift acceleration mechanism works for both electrons and pickup ions",
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