Propagating plasma patch and associated neutral stream flows |
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| Institution: | 1. Graduate Institute of Biomedical Materials and Tissue Engineering, International Ph.D. Program in Biomedical Engineering, College of Biomedical Engineering, Taipei Medical University, Taipei 11031, Taiwan;2. Cell Physiology and Molecular Image Research Center, Taipei Medical University, Wan Fang Hospital, Taipei 11696, Taiwan;3. Center for Plasma and Thin Film Technologies, Ming-Chi University of Technology, New Taipei City, Taiwan;4. Department of Materials Engineering, Ming-Chi University of Technology, New Taipei City, Taiwan;5. Department of Chemical Engineering, National Tsing Hua University, Hsinchu, Taiwan;6. Graduate Institute of Biomedical Optomechatronics, Taipei Medical University, Taipei 11031, Taiwan |
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| Abstract: | Plasma patches are regions of enhanced ionization that are created in the dayside cusp or equatorward of the cusp in the sunlit hemisphere during northward interplanetary magnetic field. After formation, and a change to a southward interplanetary magnetic field, they drift across the polar cap with the prevailing convection speed. As a plasma patch propagates, charge exchange reactions occur, which lead to the production of both ion and neutral particles throughout the patch. In the region directly above the patch, an upward jet of H+ and O+ forms. This ion jet, in turn, acts to produce an upward flux of neutral H and O stream particles because of charge exchange reactions between the ion jet and the background neutral atmosphere. A three-dimensional, time-dependent model of the ion and neutral polar winds was used in order to study the evolution of the neutral stream particles that are produced in a ‘representative’ propagating plasma patch, with the anticipation that the neutral stream particles produced by the ion jet would display a distinct signature. However, the outflow of neutral H atoms above a patch is only slightly visible in the simulation due to a continuous outflow flux of H (～109 cm?2 s?1) across the entire polar cap. On the other hand, the upward flux of neutral O from the patch is more dependent on both the state of the ionosphere and the amount of heating, with increased upward fluxes over areas where the heating is high. Typically, the upward neutral O streams are predominantly located in the pre-midnight auroral oval. |
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