PICKUP ION MEDIATED PLASMAS. I. BASIC MODEL AND LINEAR WAVES IN THE SOLAR WIND AND LOCAL INTERSTELLAR MEDIUM

dc.contributor.authorZank, G. P.
dc.contributor.authorHunana, P.
dc.contributor.authorMostafavi, P.
dc.contributor.authorGoldstein, Melvyn
dc.date.accessioned2024-01-17T11:30:04Z
dc.date.available2024-01-17T11:30:04Z
dc.date.issued2014-12-03
dc.description.abstractPickup ions (PUIs) in the outer heliosphere and the local interstellar medium are created by charge exchange between protons and hydrogen (H) atoms, forming a thermodynamically dominant component. In the supersonic solar wind beyond >10 AU, in the inner heliosheath (IHS), and in the very local interstellar medium (VLISM), PUIs do not equilibrate collisionally with the background plasma. Using a collisionless form of Chapman–Enskog expansion, we derive a closed system of multi-fluid equations for a plasma comprised of thermal protons and electrons, and suprathermal PUIs. The PUIs contribute an isotropic scalar pressure to leading order, a collisionless heat flux at the next order, and a collisionless stress tensor at the second-order. The collisionless heat conduction and viscosity in the multi-fluid description results from a non-isotropic PUI distribution. A simpler one-fluid MHD-like system of equations with distinct equations of state for both the background plasma and the PUIs is derived. We investigate linear wave properties in a PUI-mediated three-fluid plasma model for parameters appropriate to the VLISM, the IHS, and the solar wind in the outer heliosphere. Five distinct wave modes are possible: Alfvén waves, thermal fast and slow magnetoacoustic waves, PUI fast and slow magnetoacoustic waves, and an entropy mode. The thermal and PUI acoustic modes propagate at approximately the combined thermal magnetoacoustic speed and the PUI sound speed respectively. All wave modes experience damping by the PUIs through the collisionless PUI heat flux. The PUI-mediated plasma model yields wave properties, including Alfvén waves, distinctly different from those of the standard two-fluid model.
dc.description.sponsorshipThis work was supported by IBEX NASA/SwRI award NNG05EC85C, subcontract A99132BT and NASA grant NNX10AC17G. G.P.Z. appreciates discussions at the team meeting "Heliosheath Processes and Structure of the Heliopause: Modeling Energetic Particles, Cosmic Rays, and Magnetic Fields" supported by the International Space Science Institute in Bern, Switzerland.
dc.description.urihttps://iopscience.iop.org/article/10.1088/0004-637X/797/2/87
dc.format.extent30 pages
dc.genrejournal articles
dc.identifier.citationZank, G. P., P. Hunana, P. Mostafavi, and M. L. Goldstein. “Pickup Ion Mediated Plasmas. I. Basic Model and Linear Waves in the Solar Wind and Local Interstellar Medium.” The Astrophysical Journal 797, no. 2 (December 2014): 87. https://doi.org/10.1088/0004-637X/797/2/87.
dc.identifier.urihttps://doi.org/ 10.1088/0004-637X/797/2/87
dc.identifier.urihttp://hdl.handle.net/11603/31307
dc.language.isoen_US
dc.publisherIOP
dc.relation.isAvailableAtThe University of Maryland, Baltimore County (UMBC)
dc.relation.ispartofUMBC Goddard Planetary Heliophysics Institute (GPHI)
dc.rightsThis work was written as part of one of the author's official duties as an Employee of the United States Government and is therefore a work of the United States Government. In accordance with 17 U.S.C. 105, no copyright protection is available for such works under U.S. Law.
dc.rightsPublic Domain Mark 1.0 en
dc.rights.urihttps://creativecommons.org/publicdomain/mark/1.0/
dc.titlePICKUP ION MEDIATED PLASMAS. I. BASIC MODEL AND LINEAR WAVES IN THE SOLAR WIND AND LOCAL INTERSTELLAR MEDIUM
dc.typeText
dcterms.creatorhttps://orcid.org/0000-0002-5317-988X

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