Study Of Linear Stability Of Toroidal Alfvén Eigenmodes And Netron Wall Loading In Chinese Fusion Engineering Test Reactor

With the depletion of traditional energy,the development and utilization of new energy is the inevitable choice for human progress.Fusion energy is considered to be the best solution to the human energy crisis because of its abundant raw material reserves,safe and pollution-free advantages.In the magnetic confinement devices,tokamak is considered to be the most promising experimental device for achieving controlled fusion energy.The Chinese Fusion Engineering Test Reactor(CFETR)is under design.The mission of CFETR is to achieve long pulse and tritium self-sustaining steady-state operation,and to fill the gap between ITER and DEMO.Presently the preliminary conceptual design has been completed.In the fusion reactor,3.5MeV high-energy a particles are derived from deuterium tritium fusion reaction.In addition,high-energy ions produced by neutral beam inject(NBI)and ion cyclotron resonance heating(ICRH),as well as high-energy electrons produced by low hybrid wave(LHW)and electron cyclotron resonance heating(ECRH).These high-energy particles have intrinsic free energy,and the velocity of the energetic particles is close to the Alfven phase velocity,so the Alfven eigenmode instability can be excited by the wave particle resonance.In turn,the unstable Alfven eigenmode can cause redistribution or loss of high-energy particles,and may even damage the confinement wall.Therefore,the study of the interaction between high-energy particles and Alfven eigenmode is an important research topic in tokamak physics.The toroidal Alfven eigenmode(TAE)is a typical Alfven eigenmode,which is coupled by two wave modes with the same toroidal number and the adjacent poloidal mode number.Deuterium tritium fusion reaction also will produce neutrons.The neutron wall loading(NWL)indicates the fusion neutron energy flux density loaded to the first wall and it is the key factor for the materials and structure in the blankets.And it impacts the economic,performance,design,safety and environmental impact of the fusion power plant.In this dissertation the TAE stability driven by high-energy particles,and effects of kinetic profiles on neutron wall loading distribution in CFETR have been studied.This dissertation is divided into six chapters.An introduction to the dissertation is presented in chapter 1.Chapter 2 introduces the related physical research background of the high-energy particles and the shear Alfven wave in tokamak plasma.Chapter 3,chapter 4 and chapter 5 provide the main research contents in this dissertation,and conclusions for the study are summarized and the future work is presented in chapter 6.The specific contents of the dissertation are as follows:In chapter 3 NOVA/NOVA-K codes are used to study TAE stability for toroidal mode numbers in the range n = 1 to 12 in CFETR.The equilibria are constructed using the CORSICA code.Safety factor profiles are selected as the three typical profiles of ITER scenarios.For the three different safety factor profiles,we use NOVA to scan and calculate their continuum spectrum and eigenmode structures,then use NOVA-K to calculate the different damping and driving mechanisms for different toroidal mode numbers.The numerical calculation results show that TAEs found in TAE gaps are all stable for the three typical equilibrium parameters except an n = 4 TAE mode for the normal shear q.The main difference of the three equilibria is the safety factor profiles.If the safety factor profiles are chosen appropriately,then all the TAEs can be stable.Thus,it's possible to reduce the TAE instabilities by changing safety factor profiles in CFETR.We also scan the temperature and density profiles to see their effects on the TAE stability.Though the profiles are not self-consistent,our conclusions on the TAE stability are still valid for a wide range of profiles in CFETR.In chapter 4 the MHD-kinetic hybrid model used in M3D/M3D-K code and the related numerical calculation method are given.M3D/M3D-K code contains ideal MHD,resistive MHD,two-fluid,and kinetic-MHD hybrid models.Based on the CFETR new size parameters,M3D/M3D-K code is used to calculate the toroidal Alfven eigenmode linearly in this chapter.In chapter 5 we calculate neutron wall loading distribution in CFETR,and present the density and temperature profiles'effects on the NWL distribution along the FW.Our calculation results show that for 200 MW fusion power of CFETR,the maximum NWL is at the outer midplane and the vaule is about 0.4 MW/m2.The density and temperature profiles have little effect on the NWL distribution.Thus for the different operation scenarios,the kinetic profiles' effects on the NWL distribution could be neglected.The value of NWL is determined by the total fusion power.It is not necessary to consider the operation scenarios when designing the blanket structure of CFETR,if the total fusion power keeps unchanged.