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Ann. Geophys., 15, 570-586, 1997
www.ann-geophys.net/15/570/1997/
© European Geosciences Union 1997
Initial observations of fine plasma structures at the flank magnetopause with the complex plasma analyzer SCA-1 onboard the Interball Tail Probe
O. L. Vaisberg1, L. A. Avanov1, V. N. Smirnov1, J. L. Burch3, A. W. Leibov1, E. B. Ivanova1, J. H. Waite Jr.3, A. A. Klimashev2, B. I. Khazanov2, I. I. Cherkashin2, M .V. Iovlev2, A. Yu. Safronov2, A. I. Kozhukhovsky1, C. Gurgiolo3, and V. H. Lichtenstein4
1Space Research Institute, Russian Academy of Sciences, 84/32 Profsoyuznaya str., 117810 Moscow, Russia
2State Research Institute of Scientific Instrumentation, 6 Raspletina str., 123060 Moscow, Russia
3Southwest Research Institute, 6220 Culebra Road, P.O. Drawer 28510, San Antonio, Texas 78228-0510, USA
4Kurchatov Institute, Moscow, Russia
Abstract. The fast plasma analyzer EU-1 of the SCA-1
complex plasma spectrometer is installed onboard the Interball Tail Probe
(Interball-1). It provides fast three-dimensional measurements of the ion
distribution function on the low-spin-rate Prognoz satellite (about 2min). The
EU-1 ion spectrometer with virtual aperture consists of two detectors with 16
E/Q narrow-angle analyzers and electrostatic scanners. This configuration allows
one to measure the ion distribution function in three dimensions (over 15 energy
steps in 50 eV/Q–5.0 keV/Q energy range in 64 directions) in 7.5 s, which makes
it independent of the slow rotation speed of the satellite. A description of the
instrument and its capabilities is given. We present here the preliminary
results of measurements of ions for two cases of the dawn low- and mid-latitude
magnetopause crossings. The properties of observed ion structures and their
tentative explanation are presented. The 12 September 1995 pass at low latitude
at about 90° solar-zenith angle on the dawn side of the magnetosphere is
considered in more detail. Dispersive ions are seen at the edge of the
magnetopause and at the edges of subsequently observed plasma structures.
Changes in ion velocity distribution in plasma structures observed after the
first magnetopause crossing suggest that what resembles multiple magnetopause
crossings may be plasma blobs penetrating the magnetosphere. Observed
variations of plasma parameters near magnetopause structures suggest
nonstationary reconnection as the most probable mechanism for observed
structures.
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