Numerical Simulation On Lithium Transportion In Tokamak Edge Plasma

Shortage of energy was becoming ever more important and constraints the economic development of human beings. But fossil energy sources such as coal and oil are limited and burning fossil fuels gives rise to many pollution issues. Therefore we need develop new and renewable energy sources. Magnetically controlled nuclear fusion has a lot of advantages: abound raw material, controllable reaction process, and non-pollution to environment. However, we still face many giant challenges before achieving magnetically controlled nuclear fusion. With the increase of plasma parameters and the discharge time prolonged, the plasma and surface interaction has become a key problem. In order to conquer these challenges, people have to conduct experiments and numerical simulations of interaction of plasma with beryllium, carbon and tungsten, but these materials still have serious disadvantages. Recently many experiments have shown that lithium has potential advantages in nuclear fusion. With the lithium introduction, the density of impurity in core plasma drops, and the confinement time of plasma extends. In particular over ten seconds ELM-free H mode plasmas have been obtained lately in EAST by using continuous real-time injection of Li aerosol into the edge plasma.Although the lithium has brought in many advantages to plasma performance, but some key issues have not been solved, for example, how lithium impurities transport in tokamak edge plasma and how lithium interacts with background plasma. Therefore it needs urgently to do some numerical investigation on lithium transport in edge plasma. A lithium transport module has been developed based on the BOUT++, which is able to simulate plasma transport in Tokamak. The module can simulate the evolution of lithium species transport in edge plasma and the interaction with background plasma during the lithium aerosol injection from the EAST upper divertor. In chapter 1,? briefly introduce the basic knowledge about magnetic controlled nuclear fusion and some knowledge about plasma especially the application of lithium in nuclear fusion. In chapter 2,? introduce the physical model for this simulation work, including the involved particles and the reactions, governing equations, and boundary conditions (addressing how to configure the boundary conditions in BOUT++. In chapter 3, the simulation results are presented. The simulations are based on real EAST experiments. The results show the lithium transport in edge plasma and the radial profiles of lithium species. The background plasma profiles are also reported. At last, the simulation and experiment results are compared and discussed.The results show that most of lithium species move poloidally in the scrape-off-layer(SOL), while some Li species move inwards and even penetrate the separatrix into the inner region. Li species can move deeper when injected from the middle plane region. It is found that the profile of deuterium in the edge region is also changed by the introduced lithium. The friction between lithium and background plasma plays a dominant role in the reaction. By comparing simulation and the experiment results, it is found that they are in qualitative agreement.