CHARACTERIZATION OF PLASMA INSIDE THE SPT-50 CHANNEL BY ELECTROSTATIC PROBES

A large scientific research program on ion thrusters is developped in France. This work is supported in the frame of a French research program on the electric propulsion in Groupement de Recherche “Propulsion d Plasma pour Systtmes Orbitaux” involving laboratories of CNES, CNRS, SEP and ONERA. The main advantages of the Halltype Thruster are the level of thrust, the energetic characteristics and an acceptable liftetime. A laboratory SPT Thruster (SPT-50) has been tested in our facility. We show the plasma parameter evolution along the channel axis such as electron temperature, ion density, the space potential and the fioating potentiai. We determine, aiso, the electron energy distribution functions and the electric field. These measurements have been performed with electrostatic probes. We have determined three different zones inside the channel corresponding to three different discharge phenomena.