TOKAMAK DIAGNOSTICS USING AN INJECTED NEUTRAL HELIUM BEAM

THIS PROPOSAL ADDRESSES THE DEVELOPMENT OF A PLASMA DIAGNOSTIC TECHNIQUE TO MEASURE THE INTERNAL MAGNETIC FIELD AND ION TEMPERATURE PROFILE IN THE CURRENT GENERATION OF MAGNETIC FUSION DEVICES. THE TECHNIQUE WOULD UTILIZE INJECTION OF 50 MA ATOMIC HELIUM BEAM. THE HIGH BEAM INTENSITY IS GENERATED BY A NEUTRAL BEAM SOURCE DEVELOPED HERE. FROM COLLISIONAL EXCITATION OR LASER INDUCED FLUORESCENCE OF THE HE BEAM, THE ZEEMAN PROFILE OF EMITTED RADIATION CAN BE ANALYSED TO DETERMINE THE MAGNETIC FIELD. THE FLUORESCENCE TECHNIQUE CAN BE ENHANCED FURTHER BY UTILIZING COAXIAL PROPAGATION OF A DYE LASER BEAM WITH THE HELIUM BEAM. COAXIAL PROPAGATION IS READILY ACCOMMODATED BY OUR NEUTRAL BEAM SOURCE. IN ADDITION, MEASUREMENT OF THE DOPPLER-BROADENED CHARGE EXCHANGE RADIATION MAY PROVIDE A METHOD OF DETERMINING THE ION TEMPERATURE. THE MEASUREMENTS WOULD PROVIDE TEMPORAL AND SPATIAL INFORMATION NEEDED FOR A BETTER UNDERSTANDING OF PLASMA EQUILIBRIUM, STABILITY, AND TRANSPORT. IN PHASE I WEPROPOSE TO EVALUATE THE TECHNIQUES AND FORMULATE A DESIGN OFA DIAGNOSTIC SYSTEM FOR USE ON A TOKAMAK SUCH AS TFTR TO BE IMPLEMENTED IN PHASE II OF THIS PROJECT.