Simulations On The Pellet Fueliing Process For China Fusion Engineering Test Reactor

China Fusion Engineering Test Reactor(CFETR)project is now in its engineering design phase with a construction plan in next 5 to 10 years.It is the next generation of engineering test reactor for fusion energy,based on achievements by international and domestic fusion researches in decades.The main goal of CFETR is to achieve controlled deuterium-tritium(D-T)fusion and a stable power output.The deuterium-tritium fusion process in tokamak devices consumes a lot of fuel,and thus the fuel consumption of fusion needs to be compensated by refueling to keep the steady-state operations.Pellet injection is a fueling method in which the fusion fuel is frozen into a spherical solid pellet,and continuously injected into the plasma at high speed by high pressure.At present,projectile injection is a fueling method to achieve depth fueling,and provides a large selection space for adjusting the physical parameters of plasma boundary.Thus,it is a preferred feeding method for tokamak devices such as CFETR.This paper first describes the projectile ablation model of the projectile injection process,which mainly calculates how the process of the spherical projectile gradually to be dissolved from the outside to the inside after being injected into the tokamak background plasma by the bombardment of the background plasma.Then based on the projectile ablation model with different working conditions such as sizes,side injection velocities,injection from high/low field sides etc.,and under CFETR-like parameters,we study the fueling process in numerical calculations.Effects of different working conditions on the projectile loading has been studied and summarized.This article has also,by the fluid description of plasma i,established a onedimensional combustion plasma transport model,for the fueling process.This model includes the effects of D/T atoms and ions,electrons,ionization,diffusion,and fusion reaction processes,and ignores the toroidal convection and the influence of temperature change for convenience.Then the results by the projectile ablation model describing the injection/melting process is substituted into the transport model,and the transport process of the projectile under different conditions is then numerically simulated by BOUT++,a large scale magnetic confinement fusion plasma simulation software.And the feeding effect of the projectile under different conditions is obtained.Then,according to a typical feeding condition simulated above,the numerical simulation study is carried out on multiprojectile injection with different frequencies,and the feeding effect of multi-projectile injection with different frequencies is obtained.Based on the simulation method,Southwestern Institute of Physics in the nuclear industry develops a new type of projectile,cladding melting solid pellets in a deeper position to achieve a deeper depth of fueling.This paper then conducts a preliminary numerical simulation research of the new projectile,to evaluate the performance with cladding structure of new type projectile loading effect.