Study Of The Space Variations Of The Energetic He Ions At Low Altitudes In Brazilian And South Atlantic Magnetic Anomaly Region

The L distribution of 1 - 9 MeV/nuc helium ion flux observed with the low altitude Japanese OHZORA satellite<br>has a multipeak structure, different from one flux maximum of proton radiation belt and two flux maxima of<br>electron radiation belt. The peak fluxes of 1 - 3 MeV/nuc He ions are located at L=1.35-1.6, L ~ 1.8 - 2.3 (only in<br>1984), and L = 2.8 - 3.2. Recently, two low altitude satellite SAMPEX (1992 – up to now) and MIDORI (1996-97)<br>missions reported new observations of energetic He flux peaked at L ~ 2 and show the existence of stable (at<br>least with lifetime of several years) flux there at higher energies above 10 MeV/nuc in contrast to the lower<br>energies. To analyze the nature of the multipeak structure and the origin of the L=2 helium flux we studied<br>magnetic local time dependence of the peak helium fluxes observed by OHZORA. The 1 - 3 MeV/nuc helium ion<br>flux exhibits strong local-time variation at L ~ 3 having several times greater flux at the evening side at MLT =<br>17-21 hours than at the other MLT sides. The one of possible explanation of the flux variation with MLT is that ~<br>1 MeV/nuc helium ions do not drift around the Earth and are located at L about 3 due to the ion interactions<br>with the Earth's electric morning-evening field.