Auroral hot-ion dynamo model with finite gyroradii
- Advanced Technology Center, Lockheed Martin Space Systems Co., Palo Alto, California 94304 (United States)
Discrete auroras have (1) narrow size s(less-or-similar sign)30 km in at least one dimension (e.g., north-south) and (2) often rapid variation of forms, especially where the size is extremely small, s{<=}1 km. These points mesh with spatial and temporal features observed at several Earth radii in earthward flows (bursts) of hot plasma along high-latitude geomagnetic field lines. The flows (include PSBL) usually have some filamentary structure with transverse widths of a few local gyroradii of the hot protons (kT{approx}1-30 keV), i.e., widths that encompass auroral-arc size when scaled by magnetic field-line separation. At these widths, modest density gradients ({delta}n{approx}0.01-0.1 cm{sup -3}) lead to charge separation by differential mirroring of hot protons and electrons and large perpendicular electric fields. Thermal escape of ionspheric electrons into positive charge layer builds up magnetic field-aligned potential difference that accelerates hot electrons from negative charge layer into the ionosphere within auroral arc thickness. As a corollary, the model delineates a mechanism for charge-driven plasma instabilities.
- OSTI ID:
- 20860137
- Journal Information:
- Physics of Plasmas, Vol. 13, Issue 7; Other Information: DOI: 10.1063/1.2217353; (c) 2006 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 1070-664X
- Country of Publication:
- United States
- Language:
- English
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