Study For Heat Load Of Monoblocks On The Divertor Target

Developing nuclear fusion energy is the ultimate reliable way to solve the energy problems facing human being.Magnetic confinement fusion,represented by tokamak and stellarator,is one of the mainstream technical routes approaching controllable nuclear fusion energy.The fusion reaction inside burning plasmas in tokamak will release a lot of heat in the core.This heat has to be taken away timely,otherwise it will affect the stability of the core plasma.Especially when plasmas operate in several types of highconfinement mode(H-mode),the edge transport barrier with a strong temperature and density gradients will develop spontaneously,resulting in explosive edge localized modes(ELMs)which render heavy thermal loading to plasma facing components in tokamak.In particular,the interaction between the hot plasma and the first wall may cause severe damage to the wall and the contamination of the main plasmas by the produced impurities.In order to protect the first wall from over heat loading and expel the impurities,the magnetic configuration equipped with divertor is invented.In a divertor configuration,the heat flux carried by the helium ash is diverted to the divertor from the scrape-off layer,this greatly reduces the chance of direct interaction between the first wall and the plasmas.In this configuration,the divertor target becomes the most heat-concentrated part in the entire tokamak device.Under steady-state operating conditions,the average heat flux on the divertor target of the International Thermonuclear Fusion Experimental Reactor(ITER)can reach as high as10MW/m2,and the designed heat flux in the Chinese Fusion Engineering Test Reactor(CFETR)is even as high as several times of 10MW/m2.Such severe heat load introduced by the burst of large ELMs expose puts all metal target materials at the risk of melting.Therefore,if the heat load problem of the divertor target cannot be overcome,the long-pulse or steadystate operation of burning plasmas is out reach.In this regard,the study of high heat load control on the target of the divertor target has become a key frontier scientific issue in burning plasma physics research.Supported by the project "The Behavior of Divertor Materials and Components under High Heat Load Conditions"(2018 YFE0303105),belonging to "The Research on the Development of Magnetic Confinement Nuclear Fusion Energy for Intergovernmental Innovation and Cooperation of National Key R&D Program",the work of this thesis mainly aims to tackle several problems of the control of high heat load on the divertor target.Main research content includes: Building a numerical simulation model on the basic component of the divertor target for its heat transfer process,studying on the thermal response properties of the target tungsten-copper unit block under different heat load conditions,testing and evaluating the chamfering scheme for improving the service conditions of high thermal load of tungsten-copper unit blocks,and propose several possible improvement measures on it.