Paper VT-MoM1
Operational Experiences of Compact Non-Evaporable Getter Pumps in CHESS-U and CBETA

Monday, October 21, 2019, 8:20 am, Room A213

In two recently commissioned accelerator projects at Cornell Laboratory of Accelerator-based Sciences and Education (CLASSE), a large number of high pumping capacity, compact non-evaporable getter (NEG) pumps were implemented to fulfill the required vacuum performances with very tight space constraint. In the Cornell Brookhaven ERL Test Accelerator (CBETA), NEGs are the only installed pumps. At a maximum electron beam energy of 150-MeV, no beam-induced gas load is expected in normal beam operations. We have demonstrated that adequate level of vacuum (P<10^-8 torr) can be achieved quickly after a ultra-dry nitrogen venting without in situ bakeout, which provide required flexibility in the CBETA vacuum system for various beam test configurations. In contrast, very high dynamic gas-load due to synchrotron radiation induced desorption (SRID) is expected in the vacuum system for the CHESS-U Upgrade, a major upgrade project for the Cornell High Energy Synchrotron Source (CHESS). During the commissioning phase of the CHESS-U, an extremely high SRID gas load may not only cause rapid NEG saturation (thus requiring frequent NEG re-activations), but also may potentially damage the small sputtering ion pumps (SIPs) of the NexTorr® (a NEG-SIP combination pump from SAES Getters). Protective control program is developed to prevent the potential damage to these SIPs, while keeping monitoring. In this paper, we will present our operational experiences of these compact NEGs in both CBETA and CHESS-U projects.