摘要
A new gas-filled recoil spectrometer device will be built as a terminal of HIAF which will be used for a new element search with Z>119 and physics studies of the super-heavy nuclei.The vacuum pressure inside the terminal is 200 Pa when filled with helium gas however the vacuum pressure of main system is lower than 1106Pa,therefore it is necessary to design a differential vacuum system for vacuum transition more than eight orders of magnitude.Herein,a calculation of five-stage differential system is presented.
