FIRST RESULTS FROM THE PLASMA COMPOSITION SPECTROMETER PROMICS-3 IN THE INTERBALL PROJECT

PROMICS-3 is a plasma experiment flown in the Russian project Interbal l. It performs three-dimensional (3D) measurements of ions in the ener gy range 4 eV - 70 keV with mass separation and of electrons in the en ergy range 12 eV - 35 keV. The Interball project consists of two main satellites, the Tail Probe and the Auroral Probe, each with one subsat ellite. The Interball Tail Probe was launched on 3 August 1995, into a 65 degrees inclination orbit with apogee at about 30 R-E. Both main s atellites carry identical PROMICS-3 instruments and thus direct compar isons of the particle distributions will be possible once the Auroral Probe is launched. Furthermore, PROMICS-3-Tail is the first instrument measuring the 3D ion distribution function in the magnetospheric boun dary layers at high latitudes. In this paper we describe the PROMICS-3 instrument and show initial results from the Tail probe, measurements of the magnetosheath, plasma sheet, and ring current plasmas.