Neon venting of activated NEG-coated beam pipes in IHEP

Background In High Energy Photon Source (HEPS) the beam vacuum pipes employ TiZrVHf non-evaporable getter (NEG) coatings in order to meet the operation requirements. In many occasions it is inevitable to bring the sectors to atmosphere in order to open detectors, insert or change faulty parts. Consequently, NEG coatings will be saturated and followed with activation to restore the vacuum. Such an intervention would require heating up the whole sector to hundreds of degree and last from 2 to 4 weeks.
Purpose Therefore, a Neon venting system is developed in HEPS in order to perform fast interventions without losing much of the performance of the activated NEG coating.
Methods Preliminary experiments has been carried out to test the venting with Neon of different purity by comparing pumping speed lost and vacuum recovery before and after Neon venting.
Results Results show that Neon with ultrahigh purity (purified by NEG cartridge purifier) could preserve full pumping performance of the NEG coated pipes. Neon with 6 N purity could preserve half pumping performance of the NEG coated pipes, but vacuum could be fully restored in only 2 days. Neon with 5 N purity could saturate the NEG coated pipes, leading to full pumping performance lost. Therefore, Neon with 6 N purity or above is promising in applications of efficient operations in HEPS.