A fast computation of the secondary ion production in the ionosphere of Mars

Abstract

We present an analytic method for the rapid computation of secondary ion and electron production due to electron impact as suprathermal electrons produced by primary photoproduction propagate through the neutral background Martian atmosphere. We use a one-dimensional kinetic model, Trans-Mars, that solves a stationary Boltzmann transport equation to describe the ionosphere of Mars with the neutral background atmosphere (temperatures, number densities and geopotential heights) provided by a three-dimensional global circulation model, MarTIM. Parameters are given to allow the rapid computation of secondary ion production for 11 ion species (CO+2, CO++2, CO+, C+, N+2, N ++2, N+, O+2, O ++2, O+, O++) as well as for the secondary electron production. We use the neutral global circulation model to show that while the efficiency (ε) of ion and electron production (ratio of secondary to primary production) does vary with solar zenith angle it can be parametrized with a simple function, which is given. We also show that variations with solar cycle and solar longitude are negligible about the region of the primary and secondary production peaks. © 2009 RAS.