Project VARIANT: Current and field measurements on board SICH-1M satellite

International audienceVARIANT is a joint international space experiment on current density measurements in ionospheric-magnetospheric plasmas. The experiment will be performed onboard the Ukrainian remote sensing satellite SICH-1M, that will be launched in 2000 at the polar circular orbit with the inclination of around 83 degrees and altitude 670 +/- 30 km. The scientific payload includes three instruments for registration of space current density: a split Langmuir probe, a Rogovski coil and a Faraday cup. The first two of these instruments are dedicated to measure current density variations and the last the particles' fluxes. The equipment also includes sensors for measurements of the electric and magnetic field fluctuations in the frequency range from 0.1 Hz to 40 kHz. Main objectives of the VARIANT mission are as follows: (C) 2000 COSPAR

Super Dual Auroral Radar Network observations of velocity-divergent structures in the F region ionosphere

International audienceThis paper describes Super Dual Auroral Radar Network observations of an unusual mesoscale (scale size L m 300 km) structure in the auroral convection pattern. This structure is characterized by an expansion motion of the plasma in a plane perpendicular to the magnetic field and then by an anomalously high velocity divergence. This study describes those observations and eliminates possible artifacts in the data analysis. Because the radar data strongly suggest that the structure is located in the F region, the observations are thus in opposition with the well-known divergence-free motion hypothesis. They are interpreted in terms of an ion demagnetization process, in which the collisionless ions become locally collisional in the F region