Pump characteristics and degradation performance of a multilayer Ti–Zr–V film deposited on narrow tube

Nonevaporable getter (NEG) thin films provide distributed pumping properties, a low thermal outgassing rate, and a low photon and electron stimulated desorption, enabling attainment of ultrahigh vacuum in narrow and conductance-limited chambers. This technology is an ideal solution to deal with conductance-limited narrow vacuum tubes in the fourth-generation accelerator for resolving the nonuniform pressure distribution. In this study, we successfully fabricated a multilayer film structure consisting of a dense inner layer and a columnar outer layer on the inner wall of the narrow tube via magnetron sputtering deposition. The test particle Monte Carlo model was employed to accurately evaluate the sticking probability of the NEG film based on the pressure reading during gas injection. Repeated activation-saturation cycles conducted on a tube coated with the NEG film revealed the degradation characteristics of H2 and CO pumping speed/capacity and the evolution patterns of performance. This investigation thus establishes essential guidelines for sustainable operational maintenance of vacuum systems in fourth-generation synchrotron radiation facilities.