7月24日 Neutron source suitable for in situ calibration of ITER neutron diagnostics

　　报告题目：Neutron source suitable for in situ calibration of ITER neutron diagnostics

　　报告人：Timofey Kormilitsyn, Ph.D.

　　报告时间：7月24日 下午2:00

　　报告地点：四号楼6楼中间会议室

　　主持人：钟国强

　　报告人简介：Timofey Kormilitsyn is a section head at the ITER Russian Federation Domestic Agency, Moscow, Russia. He studied Plasma Physics in Moscow Institute of Physics and Technology, Russia, where obtained his B. Sc. and M. Sc. His Ph.D. degree in Plasma Physics was awarded in the year 2022 by the Joint Institute for High Temperatures of the Russian Academy of Sciences, specializing in neutron diagnostics of high temperature plasmas. He is leading the development of ITER Divertor Neutron Flux Monitor diangostic, actively contributing to the development of ITER Vertical Neutron Camera system. In this framework, he has participated in neutron diagnostics experiments on GLOBUS-M2 (RF) and EAST (People’s Republic of China) tokamaks, supervised neutron detector testing with high-yield neutron generators at Troitsk Institute of Innovation and Fusion Researches (TRINITI) and Dukhov Research Institute of Automatics (VNIIA) facilities. He is one of the key experts of the Neutron and Spectroscopy Diagnostics Division of ITER RF DA and a member of the Diagnostics ITPA expert team. He published more than 15 publications in peer-reviewed scientific journals, participated in numerous scientific conferences and meetings.

　　报告简介：In situ calibration of neutron diagnostics for a magnetic confinement fusion device is a critical task that is essential for demonstration of burning plasma performance in terms of neutron yield and fusion power, as well as for regulatory purposes. The use of high-yield compact neutron generators (NGs) for this task requires careful characterization of the neutron source. Minimization of the uncertainty of neutron source yield and energy distribution during in situ calibration of neutron diagnostics at ITER (including but not limited to Divertor Neutron Flux Monitor (DNFM) and Neutron Activation System) is done using a dedicated monitoring system. The monitoring system based on neutron counters and neutron spectrometers is provisioned with careful consideration of the realistic neutron source characteristics corresponding to the high-yield compact NG with nominal parameters of ion current of 2 mA and accelerating voltage of 220 kV. The forward-modelling approach is utilized to simulate the detector responses and count-rate levels during calibration. The NG source model considers the significant changes (0.5-1.0 MeV) in <En> and in neutron flux with irradiation angle depending on the ion beam composition and accelerating voltage of the NG. For preliminary verification of the model, several measurement campaigns were conducted with several models of NGs with D-D sealed tubes including NG-14 (Y_DD ~2e8 n/s) and NG-24 (Y_DD up to 1.2e9 n/s). The higher D-T yield and lower anisotropy of the NG-14 and NG-24 with D-T sealed tubes favors shorter irradiation times (Y_DT ~2e10 n/s and ~1.2e11 n/s respectively). Monte-Carlo analysis of neutron transport clearly demonstrates the need for a reasonable increase of irradiation campaign duration to minimize statistical uncertainty for diagnostic systems closest plasma. It is evident that neutron transport modelling importance in verification of calibration results plays a more significant role with the increase of tokamak scale and fusion power.