On Collision Frequency in the F-region

Abstract

Attempts have been made to minimize the discrepancy between the experimental and theoretical values of collision frequency of electrons in the altitude range 200-400 km where the collision with atomic oxygen is predominant. The discrepancy is about two orders of magnitude. In the absence of experimental value of collision cross-section for momentum transfer of oxygen atoms with slow ionospheric electrons (0'02-0'1 eV), the velocity dependence of cross-section deduced by Mitra <i>et at. </i>[Mitra S K, Roy B B &amp; Ghosh S B, <i>Nature Land., </i> 145 (1940),1017] and Bates and Massey [Bates D R &amp; Massey HSW, <i>Proc. R. Soc.,</i> 192A(1948), 1] from theoretical calculations has been used to resolve the discrepancy.