OXYGEN IONIZATION RATES AT MARS AND VENUS - RELATIVE CONTRIBUTIONS OFIMPACT IONIZATION AND CHARGE-EXCHANGE - COMMENT

The accuracy of estimates of electron impact ionization which are base d on the gasdynamic model of the solar wind interaction with Venus is discussed. Employing the hybrid simulations and in situ data on electr on temperature or electron fluxes the electron impact ionization is re evaluated. The electron impact ionization rate estimated in this paper is typically 4-8 times less than the value derived from the gasdynami c model Zhang et al. [1993]. During solar maximum the photoinization r ate is typically greater than the electron impact ionization rate.