CURRENT BALANCE AT AN END-PLATE OF THE GAMMA10 TANDEM MIRROR

Mesh bias experiments, in which secondary electron emission from an en dplate is suppressed, suggest that simple balance between an end loss electron current and an end loss ion current. does not hold al the end plate. An ion current flowing into the endplate from its hack side is observed, and a theoretical model is constructed which takes account o f this current and secondary electrons emitted from the mesh wires, Mi rror reflection of secondary electrons off an outer mirror throat is a lso considered in this model. The model includes the current balance a nd the endplate potential self-consistently. The current balance at th e endplate is well accounted for by this model.