Conceptual Studies of Multistage Depressed Collectors for Gyrotrons

The multistage depressed collector (MDC) shall be one of the key technologies to achieve the required gyrotron efficiency in the DEMOnstration fusion power plant. For the first time, this work presents a comprehensive study of possible gyrotron MDC concepts. Concepts, only using axisymmetric E- and B-field components are shown to be insufficient. Instead, promising concepts using the E×B drift are proposed. A detailed study of a novel MDC concept using an azimuthal electric field is presented.