HR: 09:10h
AN: SA41A-05    [PDF]
TI: Micrometeroid Flight in the Upper Atmosphere: Electron Emission and Charging
AU: * Mendis, A
EM: mendis@ece.ucsd.edu
AF: (UCSD) Department of Electrical and Computer Engineering, University of California, San Diego 9500 Gilman Drive (0407), La Jolla, CA 92093 United States
AU: Rosenberg, M
EM: rosenber@ece.ucsd.edu
AF: (UCSD) Department of Electrical and Computer Engineering, University of California, San Diego 9500 Gilman Drive (0407), La Jolla, CA 92093 United States
AU: Wong, W
AF: (UCSD) Department of Electrical and Computer Engineering, University of California, San Diego 9500 Gilman Drive (0407), La Jolla, CA 92093 United States
AU: Sorasio, G
AF: Centro de Fisica de Plasmas Instituto Superior Tecnico, Av. Rovisco Pais 1049-001, Lisboa, Portugal
AB: Solving the simultaneous equations for the continuity of charge, mass, momentum and energy of a micrometeoroid entering the earth's atmosphere, we study its charging, ablation, deceleration and heating along its path. This analysis, which considers different initial entry speeds and angles, builds on an earlier study (G. Sorasio, D. A. Mendis and M. Rosenberg, 2001, Planet. Space Sci., 49, 1257) where only normal entry at a single speed was considered, while emphasizing the important role of thermionic emission of electrons from the frictionally heated micrometeoroid. While the main conclusions are qualitatively similar, the quantitative differences are significant. As before the micrometeoroid can change its charge polarity during flight and the altitude range of meteoric ionization is larger than in the case when ionization is due only to collisions between sublimating molecules and background atmospheric molecules. However, the present study shows that this range becomes larger, with earlier onset of ionization, as the initial entry speed becomes larger and the initial entry angle becomes smaller. Interestingly we also find that the residual mass of the ablated micrometeoroid is a minimum at a certain critical angle of entry, for a given initial speed. The implications of this study for atmospheric ionization by different meteor streams, as well as for radar observations of meteors (e.g., the head and trail echoes) will be discussed. The implications of this study for atmospheric ionization by different meteor streams, as well as for radar observations of meteors (e.g., the head and trail echoes) will be discussed.
DE: 0654 Plasmas
DE: 2499 General or miscellaneous
DE: 6015 Dust
DE: 6205 Asteroids and meteoroids
SC: SPA - Aeronomy [SA]
MN: 2003 Fall Meeting