Collision frequency and transport properties of electrons in the ionosphere

Abstract

A unified ionospheric electron collision frequency model profile 〈 ν g 〉 has been calculated in the height range 50–500 km. The computed profile accounts for the electron collisions with the neutral particles as well as the ions. Experimental values of momentum transfer cross-sections have been used for electron collisions with N 2, O 2 and Ar and theoretical values for N, O, He and H. It is observed that the electron-ion collisions 〈 ν ei 〉 dominate over the electron-neutral collisions 〈 ν en 〉 above 170 km. However, 〈 ν e− N 〉 is of the same order of magnitude as 〈 ν e− O 〉 in the height range 170–210 km. Above 360 km 〈 ν e− O 〉 becomes more important among the neutrals. The temporal, seasonal and solar epoch variations of 〈 ν ei 〉 are also shown. A typical electron collision frequency profile 〈 ν g 〉 corresponding to the exospheric temperature of 1100 K has been compared with the available experimental results for D, E and F-regions obtained from different experimental techniques. This profile has been used to determine the electrical, thermal, heat flow and current flow conductivities, the mobility and the diffusivity of electrons. The results so obtained are found to be in good agreement with the earlier results.