Time-resolved 14-MeV neutron detector for triton confinement studies

Abstract

Previous measurements of triton burnup in deuterium tokamak plasmas show an anomalously small burnup for low-q discharges with significant magnetohydrodynamic activity. This may have important implications for alpha particle burnup in a fusion reactor. By developing a detector capable of time-resolved 14-MeV neutron measurements, it should be possible to separate triton confinement and slowdown anomalies. We are testing lithium-free glass scintillators which would observe 14-MeV neutrons through prompt 28Si(n, p) 28Al reactions. These detectors are not sensitive to the much larger 2.5-MeV neutron background and should also have less sensitivity to the large thermal neutron background when compared to conventional 6Li-depleted glasses. Measurements of detector sensitivity to signal and potential background sources are being performed using a 14-MeV neutron source and radioactive sources. The expected signal behavior under various DIII-D plasma and beam conditions will also be presented.