1 YIELD OF SECONDARY ELECTRON EMISSION FROM CERAMIC MATERIALS OF HALL THRUSTER WITH SEGMENTED ELECTRODES

The discharge parameters in the Hall thrusters depend strongly on the yield of secondary electron emission from the channel walls. Comparative measurements of the yield of secondary electron emission at low energies of primary electrons were performed for several dielectric materials used in Hall thrusters with segmented electrodes. The measurements showed that in low energy region the actual energetic dependencies of the yield of secondary electron emission could differ from fits which are usually used in theoretical models. For instance, at low energies of primary electrons, energetic dependencies for different dielectric materials should cross each other. The origin of the observed difference could be in surface properties, while at higher energies, where fits based on power law are relevant, properties of the material bulk play determinative role.