The Ionospheric Up-flowing He+ Ion Distribution in the Magnetosphere

Jiankui Shi and Zhenxing Liu (Center for Space Science and Applied Research, 
Chinese Academy of Sciences, Beijing, China, 100080)


Using dynamics equation, the ionospheric up-flowing He+ ion distribution along
the magnetic field line and the He+ ion distribution versus the longitude in the
magnetosphere are studied by theoretical model. The results are as follows. (1)
The ion density and flux in dayside are larger than those in nightside. (2) With
longitude changing, the higher the geomagnetic activity index Kp is, the higher
the ion density and flux, and their changing amplitude will be; the ion density
and flux when Kp=3-5 will be about ten times as that when Kp = 0. (3) When Kp =
0, the ion density has maximum at longitude 120 degree and 240 degree
respectively and minimum in the magnetotail. When Kp=3-5, the ion density has
maximum at the subsolar, and minimum in the magnetotail. However, the ion flux
has maximums at longitude 120 degree and 240 degree respectively and minimum in
the magnetotail for any Kp. Those show that the geomagnetic configuration take a
key role in the He+ ion distribution in the magnetosphere. Some results are
consistent with the observation on the He+ ion distribution by the Extreme
Ultraviolet Imager (EUV) on board the IMAGE spacecraft.

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Presented at the August 2003 AGU Chapman Conference, Helsinki, Finland