M. Gousheva

An instrument for total ion drift velocity measurements aboard the ‘Intercosmos-Bulgaria-1300’ satellite

Abstract The ‘INTERCOSMOS-BULGARIA-1300’ satellite was launched on Aug. 7/81, to investigate ionospheric plasma dynamics. It had a perigee of 825 km, an apogee of 906 km and orbit inclination of 81.2°. The satellite was three axis stabilized within ±1° on each axis. The ion driftmeter, ID-1, aboard this satellite was intended to measure ion density irregularities, the ion drift velocity and photoelectron fluxes. The purpose of this paper is to present a brief description of the ID-1 instrumentation and to show the first results obtained from the flight instrument.

Critical Ionization Velocity (CIV) experiment XANI onboard the INTERCOSMOS 24 — “ACTIVE” satellite

Abstract Satellite INTERCOSMOS-24 “ACTIVE” was launched on September 30 1989, with an initial apogee 2500 km, perigee 530 km and an orbital inclination of 82.2°. Under “ACTIVE” project, a wide number of plasma diagnostics instruments were especially designed to study the ionospheric response to high power VLF transmitter emissions, by means of satellite-subsatellite system during this mission. As a separate part of this project, a Critical Ionization Velocity (CIV) experiment called XANI (Xenon ANomalous Ionization) had been carried out to study neutral gas/plasma interaction processes in the ionosphere using neutral Xe gas injection. Seven Xe gas release experiments had been realized at daytime high latitude ionosphere. In this paper an Ion Drift Meter (IDM) and Retarding Potential Analyzer (RPA) data concerning transverse ion drift velocity vector measurements and total ion density variations during gas release experiment are shown. Two examples of the RPA data, taken after the beginning of Xe injection, show some prompt ionization at the ionization front about 30% in comparison with the background ion concentration. Horizontal ion drift of few hundred meters per second, transversal to the satellite velocity vector, had been observed at the ionization front.

First results of the Bulgaria-1300 satellite experiment

Abstract The satellite “Intercosmos-Bulgaria-1300” launched on 7 August 1981 is successfully working already more than a year. Aboard the satellite a Bulgarian scientific research complex is mounted for studying the ionosphere, magnetosphere and their mutual relations, containing 12 different instruments and systems. Below, the first results of the direct investigation of the higher atmosphere by means of different systems and instruments is presented in short: graphically we have given the distribution of the ion density obtained by processing of data obtained from one orbiting of the satellite; the optical complex working aboard Bulgaria-1300 is briefly described. The basic characteristics of the optical apparatuses are given. The optical axes of the two photometers EMO-5 and PHOTON-1, which are part of the optical complex, are orientated in nadir. UV-spectrometer works in a spectral region of 1150–2550 A with a spectral solution of 10 A. Each 3.5 min there is a spectrum of the daytime or nighttime atmosphere. These data can be used for aeronomic investigations of the higher atmosphere dynamics as well as for determining ozone. As an example of joint work and interpretation of the data from different groups of Bulgarian research devices working aboard the Bulgaria-1300 satellite, the energy deposition in the polar ionosphere as determined by measurements aboard the satellite is given.

VLF plasma waves observed during the xenon gas releases on the ACTIVE satellite

Abstract During the ACTIVE satellite mission in 1989/90, neutral xenon gas was released from the satellite. The release, 50g/sec, with velocity 250m/sec quasiperpendicular to the geomagnetic field occurred at different ionospheric altitudes. Parallel with the release process the VLF plasma waves (20Hz–20kHz) were recorded. The very high level of VLF emission during the release was registered and observed for some frequencies to extend some seconds beyond the release. It suggests for creation of expanding plasma cloud close to the satellite. It is difficult to use these observation for a clear CIV test because of incomplete darkness experimental conditions. This paper presents the observed VLF emission characteristics.