Current-voltage characteristic of the TSS-1R satellite: Comparison with isotropic and anisotropic models

In this paper we present an analysis of the satellite current-voltage (I-V) characteristics observed during the TSS-IR mission. The satellite I-V curves were compared with the predictions by two theoretical models: the first one [Parker and Murphy, 1967] considers the channeling effect of the terrestrial magnetic field as the dominating process in the current collection, whereas the second one [Alpert et al., 1965] neglects the magnetic field and assumes an isotropic spherical geometry. Even though neither of the two theories reproduces rigorously the TSS experimental situation, as they neglect both the motion of the body and possible anomalous collisions, we find that both the models, in certain conditions, could reproduce theoretical curves in agreement with the data. However we suggest that, when the effect of the plasma turbulence is considered, the data could be better interpreted on the basis of the Alpert formulation.