QUASI-EQUILIBRIUM THEORY OF THE MIDLATITUDE PROTONOSPHERE

The hydrodynamic equations for H+ and O+ ions in the midlatitude topside ionosphere are solved analytically to study the magnetic tube depletion and refilling with a thermal plasma. Explicit expressions for the electron number density in the protonosphere and the refilling time constant of the tube are obtained. The influence of the H+ ion diffusion and of charge exchange reactions is shown to be essential. It is shown that the filling of the midlatitude magnetic tubes is controlled significantly by the exospheric temperature. It is also shown that under certain conditions the depletion time may be considerably less than the refilling time. Large-scale irregularities of the electron number density can arise in the inner plasmasphere from the depletion of plasma on certain magnetic tubes.