ULF-ELF-VLF-HF PLASMA-WAVE OBSERVATIONS IN THE POLAR CUSP ONBOARD HIGH AND LOW-ALTITUDE SATELLITES

Satellite Prognoz-8 with high apogee and inclination 65 degrees was op erating in 1981. During its operation time a few crossings of the pola r cusp were registered. Magion -4 being the subsatellite for Interball -1 (Tail Probe) has a similar orbit. In January, April and May 1996 th e registration of the low frequency plasma waves during three crossing of the polar cusp were performed. A comparison of Prognoz-8 and Magio n-4 measurements gives the opportunity to identify characteristic mode s of plasma waves. There are ion-cyclotron, lower-hybrid and electron cyclotron frequencies registered. In our presentation, the spectra of electric and magnetic field fluctuation and correlation with the plasm a and magnetic held data are given. For better understanding the physi cal processes in the cusp region there are presented HF waves, high en ergy particle and thermal measurements detected at the low altitude sa tellite Apex-Magion 3 complex and Coronas. HF wave measurements indica te an enhancement of radiation in the cusp region. The observations do ne in the day sector at an altitude above foF2 and during substorm ind icate emissions in whistler mode beside the strong enhancement of broa d band radio emission which cross the local gyrofrequency and spread u p to its local electron density.