Vacuum Performance of Activated NEG Coatings under Neon Venting

Non-evaporable getter (NEG) coatings have become the main method of surface treatments for the vacuum chambers of new generation synchrotron radiation light source. Ti-Zr-V coatings are currently planned to be used in the vacuum chambers of Hefei Advanced Light Source Facility (HALF) storage ring to meet vacuum. Occasionally the vacuum chambers are inevitably exposed to the atmosphere to replace some damaged components or install insertion devices, which will damage the performance and life of NEG coatings, and take several weeks to restore the original vacuum. Therefore, a neon venting system is used, which could protect the vacuum performance of activated NEG coatings to a certain extent and avoid reactivating the coatings to prolong coatings’ lifetime and save operation time. Meanwhile, a comparative experiment is carried out under N₂ venting. After neon venting, the results show that the vacuum can meet the static vacuum degree without activating coatings to prolong the lifetime and save recovery time, but it cannot meet the static vacuum after N₂ venting. After low-temperature activation of NEG coatings, the vacuum can meet the pressure in both cases but is better under neon gas. The percentage of neon is very low in both cases by analysis of residual gases, which does not affect the stability of the beam and further proves the feasibility of neon venting.