Satellite & Space Missions

Biography

Biography: Yu V Tokarev

Abstract

Attenuation of the HF emission during crossing the Earth ionosphere is of interest as for a problem of their transport to near-earth space, and for the ground-based long-wave radio astronomy. Experiments on reception of radiation of the Russian SURA facility in the working range of 4.3-9.5 MHz onboard of the ESA-NASA WIND spacecraft give favorable opportunity to promote in this direction. Some results of these experiments in 1996…2001 years when the sp/c moved on the elliptic orbits extended in the solar direction with apogee up to one million kilometers are discussed in the report. The technique of absolute calibration of the SURA signals based on using of the cosmic background spectrum as a secondary standard is presented. The most studied mechanism of transionospheric attenuation of short waves is their absorption due to ohmic losses. At the same time, the preliminary analysis shows that the observed picture of weakening of the SURA radiation doesn't fit into the ionosphere absorption model. Evidently, the wave scattering by the ionosphere inhomogeneities as well as some phenomena of nonlinear interaction of powerful HF emission with ionosphere plasma (the SURA effective power was of 15 MW) also take part here. Noted mechanisms have various impacts to the passing radiation at frequencies above the ionosphere critical frequencies and have to be shown differently in observed signal characteristics. For solution of the question the analysis of observed features of the received signals, including transition curve, scintillation spectrum, polarization parameters and power distribution function is considered in the report.