An Investigetion on the Distribution of Ionospheric Up-Flowing He+ Ion

A theoretical model is proposed to study ionospheric up-flowing He+ ion distribution along the magnetic field line and to study the He+ ion distribution versus longitude in the magnetosphere. The results show that: (1) Along the field lines, the He+ ion's density and flux drop with increasing of the geo-center distance. (2) The higher the Kp index, the quickly the density and the flux drop. (3) The He+ ion distribution changes with the longitude, when Kp = 0 the ion's density has maximum at longitude 120 degree and 240 degree respectively, and has minimum in the magnetotail, when Kp=3-5 the ion's density has maximum at the subsolar, and has minimum in the magnetotail. However, the ion flux has maximums at longitude 120 degree and 240 degree respectively, and has minimum in the magnetotail for any Kp. (4) The results of the research for normalized density and flux of the He+ ions show that the geomagnetic configuration takes a key role in the ion distribution in the magnetosphere. Some results are consistent with the observation on the He+ ion distribution by the Extreme Ultraviolet Imager (EUI) on board the IMAGE spacecraft.