Abstract
Abstract. The dynamics of the ion distribution function near the Earth's bow shock is studied on the basis of quasi-3D measurements of ion energy spectra in the range of 30–24200 eV/q with the Russian-Cuban CORALL instrument on the INTERBALL/Tail-probe satellite. The instrument was designed for observations of magnetospheric plasma and measures ions, in an angular range of 36°–144° from the Earth-Sun direction. Ion populations generated by the Earth bow shock are often observed upstream from the bow shock. In the solar-wind stream compressed and heated by the passing of very dense magnetic cloud (CME), two types of these ion populations were measured upstream and before the bow shock crossing on 25 August 1995 at 07:37 UT. Both populations were observed in the energy range above 2 keV. At ~06:20 UT, when the angle between the direction of the interplanetary magnetic field and normal to the bow shock VBn was ≃ 43° the instrument observed a narrow, fast (~800 km/s) field-aligned beam moving from the Earth. At ~07:30, when <vartheta>Bn ≃ 28°, the wide ion pitch-angle distribution was observed. A similar suprathermal ion population is observed in the magnetosheath simultaneously with the solar-wind ion population being heated and deflected from the Sun-Earth direction. The similarity of observations during the mentioned time-interval and under usual solar-wind conditions allows us to conclude that types of suprathermal ion populations upstream and downstream from the bow shock do not depend on the solar-wind disturbance generated by magnetic cloud.
Highlights
The INTERBALL Project focuses on the study of the energy, momentum and mass transport in critical regions of the solar wind/magnetosphere system
From the beginning to 07:37 UT the satellite was in the solar wind: the main ion component exists only in a narrow cone near the Sun-Earth direction and is not registered by the CORALL instrument
The most important parameters inuencing the type of ion suprathermal population upstream from the bow shock are the position of the spacecraft in the foreshock and orientation of the interplanetary magnetic ®eld relative to the bow-shock normal (Gosling et al, 1978; Gosling and Robson, 1985)
Summary
The INTERBALL Project (a Tail probe with subsatellite launched on 3 August 1995 and an Auroral probe with subsatellite) focuses on the study of the energy, momentum and mass transport in critical regions of the solar wind/magnetosphere system. Decelerated and heated on the bow shock, the solar-wind plasma interacts with the magnetopause and provides the mass, energy and momentum source for magnetospheric processes. Energetic (!10 keV/q) ion beams are observed at the edge of the foreshock where the interplanetary magnetic ®eld convected with the solar wind ®rst encounters with the bow shock. The foreshock region upstream from the quasi-parallel bow shock is responsible for the production of energetic (or diuse) ion distribution with an energy of a few keV/q extending to over 150 keV/q (Armstrong et al 1985; Gosling and Robson 1985; Thomsen 1985; Krimigis 1987; Fuselier 1994). Unusual magnetic cloud or coronal mass ejection (CME) with very high proton density (up to 50 cmA3) were observed on 24±25 August 1995 This magnetic cloud crossed the Earth's orbit on 25 August 1995 at $02 UT and compressed and heated the solar wind and magnetosphere plasma. Presented observations may lead to a better understanding of suprathermal ion populations under dierent conditions in the solar wind
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
