Design And Optimization Of EAST-NBI Drift Duct System

Neutral Beam Injection (NBI) is one of most important methods for auxiliary heating and current drive of plasma in EAST (experimental advanced superconducting tokamak) system. EAST-NBI drift duct, which is used to connect EAST and NBI, is one of the key components of NBI, it has an important significance to reduce the energy loss of the neutral beam and improve the heating efficiency of NBI.This dissertation uses the same type equipment as a reference, formulates the design requirements of drift duct base on the requirement of EAST-NBI. The NBI group’s concept design drift duct was analyzed under the design requirements of drift duct, and points out the unreasonable parts of the structure, then we adjust structure and function of the drift duct, to make it more conform to the actual demand of EAST-NBI.Based on the adjustment structure of drift duct, the reionization losses of the neutral beam in the drift duct was analyzed, according to the analysis results and the reionization requirement of EAST-NBI, the size of drift duct was adjusted.According to the high current, high power, long pulse requirements of EAST-NBI, the beam power deposition in the internal surface of drift duct was programmed and simulated by Matlab software, and found the relationship between beam power deposition with different neutral beam divergence angle. The results showed that the main factors which affect beam power deposition in the internal surface drift duct are the energy of the neutral beam and the neutral beam divergence angle. On the basis of the simulation results, the beam power density distribution in the internal surface drift duct when the beam power deposition to the maximum value was simulated, got the maximum value of power density and its location in the internal surface of drift duct, provided the theoretical basis for the design of the drift duct, inner components and cooling system. Finally, in order to ensure that the design of drift duct structure can connect EAST and NBI, the installation process steps of drift duct was studied. The basic installation steps of drift duct was determined, and further point out the direction to realize the connection of EAST and NBI.