HELIUM ISOTOPES IN THE RADIATION BELTS OBTAINED BY HIT ONBOARD TSUBASA.

The helium isotopes were observed by Heavy Ion Telescope (HIT) onboard the TSUBASA satellite from March, 2002 to September, 2003 in the geostationary transfer orbit. The mass resolution of the HIT instrument is ~ 0.25 amu in energy range 20÷43 MeV/nucleon for helium isotopes. Helium data in the quiet periods were analyzed to obtain the spatial and temporal variation of fluxes of helium isotopes, 3He and 4He. From this analysis, the enhancement of 3He flux as compared with 4He one in low L-value was found. Both of the helium fluxes strongly fluctuated in their L-distributions in each period. [ABSTRACT FROM AUTHOR]