Design of the ITER neutral beam system beamline, United States concept

Design of a neutral beamline for the ITER (International Thermonuclear Experimental Reactor) is described. The design incorporates a barium surface conversion D source feeding a linear array of accelerator channels. The system uses a DC accelerator with electrostatic quadrupoles for strong focusing. A high-voltage power supply that is integrated with the accelerator is presented as an attractive option. A gas neutralizer is used and residual ions exiting the neutralizer are deflected to water-cooled dumps. Cryopanels are located at the accelerator exit to pump excess gas from the source and the neutralizer, and also in the ion dump cavity to pump reneutralized ions and neutralizer gas. All the above components are packaged in compact, identical, independent modules that can be removed for remote maintenance. The neutral beam system delivers 75 MW of D° into three ports with a total of nine modules arranged in stacks of three modules per port. To increase reliability, each module is designed to deliver up to 10 MW at 1.3 MeV; this allows eight modules operating at partial capacity to deliver the required power in the event one module is removed from service