A NOVEL MINIATURE OPTICAL CHOPPER FOR DEUTERIUM-TRITIUM PLASMA DIAGNOSTICS

THIS PROJECT WILL DEVELOP A NOVEL MINIATURE OPTICAL CHOPPER TO ENABLE FIBEROPTICALLY COUPLED SIGNALS TO BE DISTINGUISHED FROM RADIOLUMINESCENCE GENERATED IN THE FIBER IN A HARSH RADIATION ENVIRONMENT. FIBEROPTICS ARE IN WIDESPREAD USE IN FUSION FACILITIES TO TRANSMIT OPTICAL SIGNALS FROM PLASMAS TO REMOTE DETECTORS THAT ARE SHIELDED FROM RADIATION. HOWEVER, THE VIBERS ARE NOT RADIATION IMMUNE. LUMINESCENCE AND RADIATION INDUCED LOSS OF TRANSMISSION HAVE BEEN MEASURED IN OPTICAL FIBERS EVEN AT THE COMPARATIVELY LOW NEUTRON LEVEL OF PRESENT DEUTERIUM-DEUTERIUM PLASMAS. IN DEUTERIUM-TRITIUM PLASMAS, RADIATION EFFECTS WILL BE TWO ORDERS OF MAGNITUDE HIGHER. THE PLANNED DEVICE WILL ENABLE THE SUBTRACTION OF RADIATION INDUCED LUMINESCENCE FROM THE OPTICAL SIGNAL ORIGINATING FROM THE PLASMA. THE DEVICE IS ESPECIALLY SUITED TO THE RESTRICTED ACCESS AND HIGH MAGNETIC FIELD ENVIRONMENT OF TOKAMAKS. THE PHASE I PROJECT WILL CONSTRUCT AND TEST A PROTOTYPE DEVICE. IN PHASE II IT WILL BE INSTALLED AND OPTIMIZED IN A TOKAMAK ENVIRONMENT.