6月8日 GRS diagnostics for fast ion and RE studies

　　报告题目：GRS diagnostics for fast ion and RE studies

　　报告时间：6月8日（星期四）下午2：00-3：30

　　报告地点：控制大厅三楼会议室

　　报告人：Prof. Alexander Shevelev

　　主持人：张洋 研究员

　　报告人简介：

　　Dr Alexander Shevelev is a researcher at the Ioffe Institute of the Russian Academy of Sciences, Saint Petersburg, Russia. He studied Nuclear Physics in the St. Petersburg State Technical University (nowadays - Peter the Great St. Petersburg Polytechnic University), Russia, where obtained his M. Sc. His Ph.D. degree in Plasma Physics he obtained in the Ioffe Institute specializing in gamma-ray and hard X-ray spectrometry of high temperature plasmas. He studied runaway electrons and fast ions at the GLOBUS-M2, TUMAN-3M, FT-2 (RF), JET (UK), and ASDEX Upgrade (Germany) tokamaks, participated in and supervised the development of diagnostic equipment for plasma facilities based on the use of gamma-ray, HXR, and neutron spectrometry methods, supervised nuclear physics research at the cyclotron of the Ioffe Institute. He is a member of the Russian diagnostic team in the ITER Project and leader of the Gamma-ray Spectrometry group in the Ioffe Institute, member of the Diagnostics and Energetic Particle ITPA expert teams. He published more than 100 publications in peer-reviewed scientific journals, participated in numerous scientific conferences and meetings.

　　报告简介：

　　Spectrometry of gamma and hard X-rays in tokamak facilities provides information on fast ion and runaway electron distributions in plasma.  The source of gamma-rays is nuclear reactions between energetic confined ions and plasma impurities, i.e. Be, C, B and bulk plasma ions. Gamma-ray spectrometry of the plasma is a tool giving information on the heating efficiency and fast-ion confinement. Using capabilities of the gamma-ray spectrometry, fusion born alpha-particles were studied in recent D-3He plasma experiments on JET. Fast deuterium ions of the neutral beam injection (NBI) heating were accelerated to MeV energies with three-ion scenario D–(DNBI)–3He using radio frequency waves in the ion cyclotron range of frequencies (ICRF). A high reaction rate allowed to measure the alpha-particle production rate and their spatial distribution in the plasma by detecting 16.7-MeV gamma-rays from the 3He(D,γ)5Li reaction, which is a weak branch of 3He(D,p)4He reaction.

　　Disruptions of a discharge in tokamaks are often the reason for the formation of populations of high-energy runaway electrons. The control of the generation of runaway electrons in a tokamak plasma is a necessary condition for safe operation at large plasma facilities such as JET or ITER. Two gamma-ray spectrometers based on LaBr3(Ce) scintillation crystals were developed and put into operation at the ASDEX Upgrade tokamak to be used in experiments with the runaway generation in discharges with massive gas and pellet injections. RE distributions were reconstructed in the energy range up to 30 MeV using the DeGaSum code developed in the Ioffe Institute. The analysis of the obtained RE distributions provided the assessments of the gas target's density. The experience obtained in experiments on JET and AUG is used in the development of gamma-spectrometry systems on new generation tokamaks.