Collisions in Multi-Species Plasmas

Models of ionospheric conductivity implicitly assume that the total collisional scattering of ions and electrons driven by ambient electric field is a simple sum of the collisional scattering for ions and electrons with each neutral species in the ionosphere. Because the closure of magnetospheric current systems through the ionosphere determines the magnetospheric response to space weather events, accurate models of ionospheric conductivity are in great demand. What is missed in the simple models of collisions in multispecies ionospheric plasmas is the contribution to the total collisional scattering by excited states of ions and neutrals, the effect of a background ion and electron constituent, and scattering by molecules formed from ionospheric components. In this work, we present initial measurements of total scattering cross sections in single species and multispecies gases at ionospherically relevant parameters. Future measurements will be completed in the presence of a background plasma.