Perspectives of neutral beam injection techniques

Some of the problems associated with the design of a high energy neutral injector are described: plasma source, beam extraction and acceleration, neutralizer design, direct energy recovery. The role of the cryopumps and the main high voltage power supply is underlined. It is concluded that the major uncertainty in the next generation of injectors is the question of power loading in the beam extraction and acceleration structure, and the limits this will impose on the overall transparency and transmitted power density for long pulse operation (40 references)