Speaker
Description
Gamma-ray diagnostics play a crucial role in the study of high-energy particle behavior and nuclear processes in tokamak plasmas. Information on the alpha particles produced in fusion is of paramount importance for burning plasma device, such as ITER [1-2]. The fusion rate can be determined by measuring the fluxes of 17-MeV gamma quanta born in D-T fusion reactions, and the fusion product can be obtained by measuring and analyzing gamma-ray lines that are characteristic of nuclear reactions between alpha particles and plasma impurities.
A new facility, the Burning plasma Experimental Superconducting Tokamak (BEST), is being constructed in China. Gamma-ray diagnostics, consisting of the radial gamma-ray camera (GRC) with 7 line-of-sights, the vertical GRC with 4 line-of-sights and radial gamma-ray spectrometer with 3 line-of-sights, have been designed to provide measurement of alpha particles and runaway electrons for BEST tokamak. In this report, the preliminary design of gamma-ray diagnostics for BEST tokamak will be presented for the first time, including the system configuration, the design of detectors, magnetic shielding, neutron filters and data acquisition system and so on. The technical challenge to measure the gamma-ray lines on BEST tokamak with a high magnetic field and strong neutron flux background will be discussed. Two types of new detectors have been designed and fabricated to against from strong stray magnetic field. One is LaBr3(Ce) crystal coupled with SiPM, and another one is LaBr3(Ce) coupled with liquid light guide and PMT. The prototypes detectors have been developed and validated on EAST tokamak for their performance evaluation. Moreover, the design and development of synthetic gamma-ray diagnostic in IMAS infrastructure [3] will be introduced, which is mainly used to optimize the diagnostic performance, as well as to support the gamma-ray spectrum deconvolution and reconstruction of alpha particles distribution function.
[1] A. Shevelev et al., Nucl. Fusion 53 (2013) 123004.
[2] M. Nocente et al., Nucl. Fusion 57 (2017) 076016
[3] F. Imbeaux et al., Comp. Phys. Communications 181 (2010) 987–998
