Plutoʹs ionospheric models and solar wind interaction Original Research Article

Chemical model calculations are carried out to describe the ion composition and density profile of Plutoʹs ionosphere. With the adopted surface pressure (≈ 10 microbars) of the N2 gas and the mixing ratio of CH4 (≈7.4×10−3), the major ion is found to be H2CN+ and the peak ion number density is estimated to be about 3×103 cm−3. If Pluto does not have an intrinsic magnetic field, the ionospheric penetration of the interplanetary magnetic field and solar wind plasma would be stopped at an altitude of about 1400 km because of collisional friction of the neutral atmosphere.