TSS-1R ELECTRON CURRENTS - MAGNETIC LIMITED COLLECTION FROM A HEATED PRESHEATH

We show that currents collected by TSS-1R are consistent with Parker-M urphy magnetic limited collection from the ionosphere where the local electron temperatures are elevated as observed during the first TSS-1 mission. An analytic development of the previous Katz et al. [1994] pr esheath model is presented. This model accounts for the heating that o ccurs as electrons fall through the potentials necessary to reflect th e ram ions while satisfying the Bohm sheath stability criterion. This presheath model is coupled to; a sheath sized to the Parker-Murphy col lection radius to predict the current collected by TSS-1R. The resulta nt currents are 2 to 3 times larger than for the standard Parker-Murph y collection model and are consistent with observations.