Abstract
General Fusion is building the Fusion Demonstration Plant to demonstrate a magnetized target fusion scheme in which a deuterium plasma is heated from 200 eV to 10 keV by piston-driven compression of a liquid-lithium liner. The multilayer coaxial time-of-flight neutron emission spectrometer is designed to measure the ion temperature near peak compression at which time the neutron yield will approach 1018 neutrons/s. The neutron energy distribution is expected to be Gaussian since the machine uses no neutral beam or radio-frequency heating. In this case, analysis shows that as few as 500 coincidence events should be sufficient to accurately measure the ion temperature. This enables a fast time resolution of 10 µs, which is required to track the rapid change in temperature approaching peak compression. We overcome the challenges of neutron pile-up and event ambiguity with a compact design having two layers of segmented scintillators. The error in the ion temperature measurement is computed as a function of the neutron spectrometer’s geometric parameters and used to optimize the design for the case of reaching 10 keV at peak compression.
P. J. F. Carle, F. Retière, A. Sher, R. Underwood, K. Starosta, M. Hildebrand, S. Barsky, S. Howard; Neutron emission spectrometer to measure ion temperature on the Fusion Demonstration Plant. Rev. Sci. Instrum. 1 November 2022; 93 (11): 113539. https://doi.org/10.1063/5.0101814. Proceedings of the 24th Topical Conference on High-Temperature Plasma Diagnostics. May 15-19, 2022. Rochester, New York.
