NEGATIVE-ION SOURCES FOR NEUTRAL BEAM INJECTION INTO FUSION MACHINES

Plasma heating and current drive in future machines for magnetically c onfined thermonuclear fusion will require neutral beam injectors based upon negative ion sources. Although the technology of filament are io n sources is considered adequately mature for large scale injectors, s uch as for ITER, ion source efficiency and reliability need to be impr oved. The power loading of the source and accelerator are especially p roblematic. This is particularly important for long pulse (1000 s) ope ration. Investigations with the Kamaboko source, a small scale model o f the ITER are source, illustrate the importance of the conditions of the plasma grid for reducing electron loading of the accelerator. (C) 1998 American Institute of Physics.