|
|
 |
|
|
Ann. Geophys., 15, 533-541, 1997
www.ann-geophys.net/15/533/1997/
© European Geosciences Union 1997
Ion distribution dynamics near the Earth's bow shock: first measurements with the 2D ion energy spectrometer CORALL on the INTERBALL/Tail-probe satellite
Yu. I. Yermolaev1, A. O. Fedorov1, O. L. Vaisberg1, V. M. Balebanov1, Yu. A. Obod1, R. Jimenez2, J. Fleites2, L. Llera2, and A. N. Omelchenko3
1Space Research Institute, Russian Academy of Sciences, Russia
2Intercosmos, Republic of Cuba
3Institute of Applied Geophysics, Russian Hydrometeorological Service, Russia
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.
Full Article in PDF (1426 KB) |
|
|
