SUPERHEATED DROP DETECTOR TO MEASURE THE D-D/D-T RATIO FOR NEUTRONS FROM PLASMA CONFINED FUSION

THE PERFORMANCE OF A FUSION GENERATOR DEPENDS, IN PART, ON ACCURATE MEASUREMENTS OF THE NUMBER OF NEUTRONS BEING PRODUCED FOR A GIVEN OPERATING CONDITION AND THE RATIO OF NEUTRONS FROM DEUTERIUM-DEUTERIUM AND DEUTERIUM-TRITIUM REACTIONS. DIRECT AND RAPID MEASUREMENTS OF THIS RATIO AT SEVERAL LOCATIONS ABOUT THE PLASMA CAN PROVIDE INFORMATION ON THE UNIFORMITY OF NEUTRON PRODUCTION AS WELL AS THE RADIAL POSITION OF THE FUSING PORTION OF THE PLASMA. THE APPLICANT PROPOSES TO ADAPT SUPERHEATED DROP (SDD) COMPOSITIONS, RECENTLY INTRODUCED BY THE APPLICANT'S ORGANIZATION FOR HEALTH PHYSICS APPLICATIONS, FOR THIS CHALLENGING FUSION MEASUREMENT TASK. THESE SDD COMPOSITIONS, CONTAINING TENS OF THOUSANDS OF SUPERHEATED DROPS IN A HOST GEL, RESPOND TO NEUTRONS THROUGH THE INITIATION OF DROP VAPORIZATION, AS IN THE BUBBLE CHAMBER. THE RESULTING VAPOR BUBBLES OCCUPY 250 TIMES THE VOLUME OF THE DROPS THAT CREATED THEM, THEREBY LEADING TO A MACROSCOPIC NON-ELECTRONIC MEASURE OF THE TOTAL NUMBER OF NEUTRONS TO WHICH THE COMPOSITION WAS EXPOSED. MOREOVER, SUPERHEATED DROP COMPOSITIONS EMPLOYING DIFFERENT SENSITIVE MATERIALS HAVE DIFFERENT ENERGY THRESHOLDS. BY USING ONE MATERIAL WITH A 2 MEV THRESHOLD, A COUNT OF BOTH D-D AND D-TNEUTRONS CAN BE OBTAINED. BY USING ANOTHER COMPOSITION WITHA 6 MEV THRESHOLD, COUNTS OF JUST 14 MEV NEUTRONS FROM THE D-T REACTION WILL BE OBTAINED. THUS THE D-D/D-T RATIO CAN BE COMPUTED. THE PROPOSED PROJECT WILL EXPLORE THE RANGE OF CONDITIONS UNDER WHICH THE SDD SYSTEM WILL OPERATE IN THE PLASMA FUSIONENVIRONMENT, WILL PROPOSE MODIFICATIONS IN THE SDD COMPOSITIONS TO MEET THESE OPERATING CONDITIONS, AND WILL DECIDE AMONG A NUMBER OF OPTIONS FOR READING OUT THE CHANGESMANIFESTED IN THE COMPOSITION AFTER THEY HAVE BEEN EXPOSED AT SEVERAL POSITIONS ABOUT THE FUSING PORTION OF THE PLASMA.