Pyroelectric crystal neutron production in a portable prototype vacuum system

Pyroelectric crystals are being used to ionize and accelerate D2 gas into a deuterated target to achieve D–D fusion at Rensselaer Polytechnic Institute (RPI). Previous results from RPI yielded up to 5.9×104 neutrons over one thermal cycle; however, these results were not reproducible from one experiment to another. A portable prototype vacuum system has been developed that enhances reproducibility of results. A thermal management system consisting of two thermoelectric module temperature controllers was developed to improve the reproducibility of the thermal cycle. Twenty-eight experiments were conducted over a period of three days to determine the optimum ambient gas operating pressure of the vacuum system. The optimum operating pressure was found to be 26 mTorr which is much higher than operating pressures that have been previously reported. Reproducibility of the results has been improved. At optimum pressure, five consecutive experiments yielded an average of 9×103 neutrons with a standard deviation of 14% for each thermal cycle. While the neutron yield is lower than previous results, increased reproducibility in a more stable vacuum environment may allow for an increase in neutron yield in the future.