Start-up and early results from Alcator C-MOD

Alcator C-MOD is a compact, high performance tokamak designed to address reactor-relevant issues including diverter operation, confinement, and auxiliary heating. It incorporates flexible shaping of non-circular, diverted plasmas, strong ICRF heating, and many innovative engineering features to achieve high performance in a compact device with modest cost. Like its predecessors, Alcator A and Alcator C, Alcator C-MOD uses cryogenically cooled copper magnets to produce high toroidal fields (9 Tesla at 0.67 m) and strong ohmic heating (up to 3 MA.) The thick wall of the vacuum vessel, while complicating the normal problems of plasma initiation and control, are relevant to virtually all next-generation designs. The facility operated briefly in late 1991 and again in early 1992, when a terminal failed on one of the PF magnets. The experiment resumed operations in May 1993. This report describes the start-up and early operational experience, comparing with both design scenarios and previous experience on Alcator A and C. Results from operations during the summer of 1993 are presented.