LUMPED NEG PUMP FOR CROTCH AND PUMPING SYSTEM OF SPRING-8 STORAGE RING

A prototype of the lumped NEG pump (LNP) designed as a main pump of th e crotches and absorbers of the storage ring was manufactured with 14 nonevaporable getter (NEG) modules and a cylindrical pump body made of an aluminum alloy. Vacuum performance and operating characteristics o f the LNP have been tested. Initial pumping speeds of the LNP for H-2, CO, N2 and CO2 were typically 3 m3 s-1, 1. 7 m3 s-1, 1 m3 s-1 and 1.3 m3 s-1, respectively. The experimental results were compared with pum ping speeds calculated by the Monte Carlo method The pumping speed of the practical LNP to be installed in the storage ring was also calcula ted. The pumping system, which is composed of these LNPs and NEG strip s to be installed in the vacuum chambers, was described. Based on this pumping system, the calculated pressure profile of the storage ring i s also presented.