Altitude profiles for O+ ion velocity distribution functions, O+ parallel and perpendicular temperatures, O+ temperature anisotropy, O+–O+ and O+–O collision frequencies and O+ temperature partition coefficients β|| and β⊥ are obtained in the auroral ionosphere (150 km–500 km). A Monte Carlo simulation was used to investigate the behavior of O+ ions that are E×B drifting through a background of neutrals O, with the effects of O+–O resonant charge exchange and polarization interactions as well as O+–O+ Coulomb collisions. We have found, for low altitudes, the effect of O+–O+ Coulomb collisions is negligible and, as electric field increases, O+–O collision rate increases, therefore non-Maxwellian features of fO+ appeared and becomes pronounced at large electric fields, O+ temperature increases, νO+–O increases, νO+–O+ decreases, O+ temperature partition coefficients β|| decreases and β⊥ increases. As altitude increases, the effect of O+–O+ Coulomb collision becomes significant, and for constant electric field, the non-Maxwellian features of O+ distributions are reduced, T⊥O+ decreases, T|| O+ increases, O+ temperature anisotropy decreases, νO+–O decreases, νO+–O+ increases with altitude and reaches its maximum at 300 km and then decreases, β|| increases and β⊥ decreases. However, as E increases, the O+–O collision frequency increases, while O+–O+ collision frequency decreases, β|| decreases, β⊥ increases, νO+–O increases, νO+–O+ decreases. Monte Carlo simulation of the effect of O+–O+ Coulomb collision on the O+ temperature partition coefficients β|| and β⊥, which has not been taken into account so far, is to increase β|| and decreases β⊥. We believe that the Monte Carlo calculations presented here provided the best description to date of auroral F-region O+ velocity distributions, O+ temperature and O+ temperature partition coefficients β|| and β⊥ in the presence of the electric field, primarily because of the self consistent handling of O+–O+ and O+–O collisions.

Title

J. Phys. Soc. Jpn. 72 (2003) pp. 3006-3013 (8 Pages)

Publisher

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Publisher Country

Palestine

Publication Type

Both (Printed and Online)

Volume

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Year

2003

Pages

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