Research on the particles release of Ti-Zr-V thin film coatings

Abstract Non-evaporable getter (NEG) films have been widely used in particle accelerators, especially in diffraction limited storage ring (DLSR) to achieve efficient pumping in narrow vacuum chambers. Due to the advantage of NEG films to achieve distributed pumping and barrier to mitigate hydrogen permeation from vacuum chamber, they could be the candidate processing of vacuum chambers near superconducting radio frequency cavities (SRFC), to help to get ultrahigh vacuum (UHV) environment with minimal hydrogen partial pressure. Additionally, the particle release characteristics of NEG films should be investigated carefully to ensure a particle free (PF) vacuum environment in high acceleration gradient SRFC, in which the particles on surface would cause field emission and even the quench of SRFC. For this purpose, approximately 1 μm thick columnar Ti-Zr-V thin film had been deposited on OFC and CuZr chambers and the microstructure were characterized. Stringent cleaning and assembly procedures had been implemented to measure particles release from Ti-Zr-V thin film coatings by the particle counter (PC) after several activations. The results indicate that very few particles were released from the NEG film coatings, even under high-pressure filtered and ionized N 2 blowing, with the release quickly tending towards zero due to the strong adhesion between the NEG film and the substrate. Besides, the findings demonstrate a gradual decrease in the quantities of particles released from the NEG film coatings as the number of activations increases. Based on these particles release characteristics, this study demonstrates the potential application of NEG film coatings in particle-sensitive environments, including particle accelerators with SRFC.