Abstract
A middle-sensitivity scintillating fiber detector (hereafter middle Sci-Fi detector) that works at a deuterium-tritium neutron flux of ~105-107 cm−2s−1 was utilized to measure secondary deuterium-tritium neutron emission rates with high temporal resolution at a total neutron emission rate of 1013 to 1015 n/s, where strong magnetohydrodynamic (MHD) instabilities were observed in the large helical device deuterium plasma experiments. The gain and angular characteristics of the middle Sci-Fi detector were evaluated in an accelerator-based deuterium-tritium neutron source in the intense 14 MeV neutron source facility at Osaka University. Observation of 1 MeV triton transport due to MHD instability was performed by a middle Sci-Fi detector whose deuterium-tritium neutron counting rate was approximately 20 times higher than that of the conventional Sci-Fi detector. Fusion-born triton transport due to energetic-particle-driven MHD instability was observed using the middle Sci-Fi detector due to its high detection efficiency and high discrimination ability of deuterium-tritium neutrons from the sea of deuterium-deuterium neutrons.
Highlights
Energetic particle confinement is one of the issues for achieving and sustaining a deuterium-tritium (DT) fusion burning plasma because the plasma is mainly heated by alpha particles created by DT fusion reactions
5 Summary To understand MHD instability-induced fusion-born transport, a middle scintillating fiber (Sci-Fi) detector that covers a DT neutron flux of 105 to 107, which corresponds to an Sn value of 1013 to 1015 n/s in the large helical device (LHD), was developed
Time-resolved measurement of DT neutron flux was performed in the LHD
Summary
Energetic particle confinement is one of the issues for achieving and sustaining a deuterium-tritium (DT) fusion burning plasma because the plasma is mainly heated by alpha particles created by DT fusion reactions. The number of Sci-Fi detectors must be ~500 times larger than that of the compact SciFi detector to enhance the detection efficiency by ~500 times, experiments showed that the operational range of Sn of the sizable detector is approximately 105 times lower than that of the compact Sci-Fi detector, i.e., an Sn value of ~1010 to ~1012 n/s in the LHD due to the relatively low directivity of ~50 degrees This manuscript shows the characterization of a new middle-sensitivity Sci-Fi detector (hereafter middle Sci-Fi detector) for understanding DD fusion born-triton transport due to MHD instabilities, where Sn values of ~1013 n/s to ~1015 n/s in the LHD correspond to a DT neutron flux 105107 cm−2s−1 at the torus hall.
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