Abstract:
Controllable fusion energy, with its advantages of safety, cleanness and abundant fuel source, is considered one of the main alternatives for humans to solve the energy problem in the future. In a magnetic confinement fusion device, the high heat and particle flux released from high temperature plasma would strongly interact with the plasma facing components (PFCs). The interaction would damage the PFCs and produce impurities that degrade plasma confinement. Meanwhile, the increased recycling of the particles trapped on the walls would affect the control of plasma density. The control of the interaction between the plasma and walls is of vital importance to the achievement of long pulse plasmas with high parameters. The research efforts in this area have mainly focused on the choice of suitable plasma facing materials, effective treatment of PFCs surface, reduction of particles and high heat flux released from plasma, and increasing heat exhaust with the help of developing efficient cooling structures of PFCs. After decades of research, especially in EAST superconducting tokamak in China, a series of great advances have been made. The advantages of wall materials, such as graphite, tungsten, beryllium and molybdenum, have been realized; a few effective methods for wall surface cleaning and coating have been developed; a variety of advanced methods to reduce the heat flux released from plasma have been successfully explored; various structures of PFCs to increase heat exhaust have been designed and tested. The results of these investigations have been successfully explored in EAST, effectively promoting the achievement of the world record of high confinement mode plasma with long durations, more than 100s. The control of the interaction between plasma and walls is still facing big challenges for the future fusion reactors with a high energy neutron irradiation, a much higher heat load and much longer plasma pulse than that in the present tokamaks.
