The ultra-high vacuum system of HIRFL-CSR

HIRFL-CSR, a new accelerator project planned at the Heavy Ion Research Facility in Lanzhou (HIRFL), is a multipurpose cooling storage ring (CSR). To minimize the beam loss due to charge exchange of very heavy ions with the residual gas molecules, ultra-high vacuum of 3×10−9Pa is required for the HIRFL-CSR facility, which is the lowest pressure in a large vacuum system in China up to now. In this article we describe: (1) design of the system; (2) vacuum chambers; (3) reduction of the outgassing rate; (4) vacuum equipment; (5) pressure distribution; (6) future programme