中性束注入器真空系统差分抽气性能优化研究

中性束在真空室内传输的过程中需要一个真空梯度分布的环境,EAST中性束注入器(NBI)的真空室采用差分式结构来满足真空梯度分布的要求。真空室内气体挡板安装位置的不同会影响真空空间气体分子密度分布,从而对真空梯度的分布产生影响。运用Molflow软件模拟分析气体挡板在不同安装位置情况下,真空室内真空梯度和后低温冷凝屏热负荷分布的分布情况,分析得出了L=1.35~1.38 m是气体挡板最佳的安装位置。为CFETR NBI真空室的真空梯度的设计提供一定的借鉴和参考。

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).