Nuclear Science and Techniques

Abstract:

An accelerator storage ring needs clean ultrahigh vacuum. A TiZrV non-evaporable getter (NEG) film deposited on interior walls of the chamber can realize distributed pumping, effective vacuum improvement and reduced longitudinal pressure gradient. But accumulation of pollutants such as N₂ and O₂ will decrease the adsorption
ability of the NEG, leading to a reduction of NEG lifetime. Therefore, an NEG thin film coated with a layer of Pd, which has high diffusion rate and absorption ability for
H₂, can extend the service life of NEG and improve the pumping rate of H₂ as well. In this paper, with argon as discharge gas, a magnetron sputtering method is adopted to
prepare TiZrV-Pd films in a long straight pipe. By SEM measurement, deposition rates of TiZrV-Pd films are analyzed under different deposition parameters, such as magnetic field strength, gas flow rate, discharge current, discharge voltage and working pressure. By comparing the experimental results with the simulation results based on Sigmund’s theory, the Pd deposition rate C can be estimated by the sputtered depth.

Key words: TiZrV-Pd, Deposition rates, Magnetron sputtering method, Non-evaporable getter