Optimization of Differential Pumping Unit for Neutral Beam Injector of Experimental Advanced Superconducting Tokomak:A Simulation Study

The flow field,in the vacuum environment with a pressure gradient distribution and realized by the self-developed pumping unit to meet the requirements of neutral beam injector(NBI) of Experimental Advanced Superconducting Tokomak,was empirically approximated,mathematically modeled,theoretically analyzed and numerically simulated in Monte Carlo method with Molflow software for optimization of pumping conditions.The original work involved the thermal load distribution of cryo-panel of cryo-condensation pump.The influence of the gas-baffle position on the distributions of molecules density and pressure in the vacuum chamber,and thermal-load profile on cryo-panel was investigated.The simulated results show that the optimized installation position of gas-baffle will be 1.35~1.38 m away from the gas inlet of NBI.We suggest that the simulated results be of some technological interest in design of vacuum system for NBI of China Fusion Engineering Test Rector(CFETR).