### Energetic ion distributions on both sides of the Earths magnetopauseEnergetic ion distributions on both sides of the Earths magnetopause

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 Author Paschalidis, N. P. ♦ Krimigis, S. M. ♦ McEntire, R. W. Source United States Department of Energy Office of Scientific and Technical Information Content type Text Language English
 Subject Keyword PHYSICS ♦ TAIL IONS ♦ DISTRIBUTION FUNCTIONS ♦ MAGNETOPAUSE ♦ SATELLITES ♦ REMOTE SENSING ♦ SHOCK WAVES Abstract The AMPTE/CCE spacecraft, with an apogee of {approximately}8.8R{sub E} and an inclination of {approximately}4.3{degrees}, sampled the outer dayside equatorial magnetosphere for extended time periods and often crossed into the magnetosheath whenever the solar wind pressure was sufficiently high to compress the magnetopause to <8.8R{sub E}. The authors have analyzed ion distributions on both sides of the magnetopause in order to investigate any local time and energy dependence, giving information about physical processes at the magnetopause and the bow shock. Particle measurements are from the CHEM (1.5 to 300 keV/e) and MEPA (10 keV to 2 MeV) instruments. The wide total energy range (1.5 keV to 2 MeV) covered describes the magnetospheric distributions quite well, and for the purpose of this study, adequately describes the high-energy part of the shocked solar wind. Case studies of representative magnetopause crossings at dawn, noon, and dusk, as well as a survey of several other crossings, indicated: (1) a local time and energy dependence of magnetosheath spectra at energies {ge}50 keV; spectra were harder at the duskside than at the dawnside and also correlated with magnetospheric activity, (2) constantly much higher intensities in the magnetosphere than in the magnetosheath at energies > 10 keV and an earthward gradient in the subsolar magnetosheath. In addition to the steady state magnetosheath population there exists a burst-type component indicative of a magnetospheric source, and most of the time this is recognized as a flux transfer event. Overall, the results about the origin of the {ge}50 keV magnetosheath ions are consistent with the continuous leakage of magnetospheric particles across a tangential discontinuity magnetopause, locally distributed according to magnetospheric drift paths. However, in order to examine the relative strength and local time distribution of all possible sources at these energies, a detailed analysis is required. 41 refs., 15 figs. ISSN 01480227 Educational Use Research Learning Resource Type Article Publisher Date 1994-05-01 Publisher Place United States Journal Journal of Geophysical Research Volume Number 99 Issue Number A5