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Session 36 - Solar Activity.
Display session, Tuesday, June 11
Tripp Commons,

[36.08] Ion-Neutral Separation in the Chromosphere

J. D. Huba (Plasma Physics Division, Naval Research Laboratory)

One of the most perplexing problems in solar system composition is the discovery that the elemental abundances in the photosphere are different from those in the corona, solar wind, and solar energetic particles -- there is an enrichment of low, first ionization potential (FIP) elements above the chromosphere. The differentiation is believed to occur in the chromosphere where ions and neutrals coexist. However, existing models low FIP fractionation are qualitative and/or neglect time-dependent plasma dynamics. We present a model designed to understand and model the physical processes that can separate ions and neutrals, (2) to provide quantitative analyses of these processes for parameters relevant to the chromosphere, (3) to determine the time and space scales over which ion-neutral separation can occur, and (4) to relate these results to the enrichment of low FIP elements in the upper solar atmosphere. The physical model is based upon electrostatic theory (valid for \beta << 1 and \partial B/\partial t=0). The driving forces to be considered that can separate the ions and neutrals are neutral gas flows and electric fields transverse to the ambient magnetic field. Preliminary 2D simulation results will be presented to demonstrate ion/neutral separation.

Work sponsored by NASA.

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