PERFORMANCE CHARACTERISTICS OF NBSTF, THE PROTOTYPE NEUTRAL-BEAMLINE FOR TFTR

The Neutral Beam System Test Fac i l i ty (NBSTF) at the Lawrence Berkeley Laboratory is a shielded f a c i l i t y for prototype development and testing of the multl-megawatt neutral-beam injection system for the Tokamak Fusion Test Reactor (TFTR) at the Princeton Plasma Physics Laboratory, NBSTF includes: a power system capable of regulated, rapidly switched 120-kV, 75-A, 1.5-sec pulses every three minutes; the cryopumped TFTR prototype beam!ine with calorimeter, sweep magnet, ion dump, duct, and a target calorimeter; and a computer controls and diagnostic system. Beam-diagnostic systems include: temperature prof i les on calorimeter, target dump, and ion dump; temperature measurements on neutralizer and beam scrapers; water-flow calcrimetry; Doppler-shift spectroscopy and an electrostat ic analyzer; and an array of pressure gauges to determine gas d i s t r i ­ bution. Beam operation at 120 kV, 65 A, 0.8 sec has been achieved with a molecular-ion mixture of 60XD+ /3D% Dj/lOX Dt . Limited operation with an improved plasma source "has yielded 80X D+/15XD^/5XDl at 120 kV, 67A, 0.5 sec. The estimated l? ' keVD° power delivered with twelve 1on sources to .rTR is 17 +/2 MW for the standard plasma source and 22 +/-4 MW for the improved source.