Nuclear Science and Techniques | 2021
Activation and pumping characteristics of Ti–Zr–V films deposited on narrow tubes
Abstract
Non-evaporable getter (NEG) films are an integral part of many particle accelerators. These films provide conductance-free evenly distributed pumping, a low thermal outgassing rate, and a low photon-and electron-stimulated desorption. These characteristics make it an ideal solution for resolving the non-uniform pressure distribution in conductance-limited narrow vacuum tubes. In this study, ternary Ti–Zr–V films were deposited on Si substrates and Ag–Cu (Ag 0.085 wt%) tubes with an inner diameter of 22 mm. All Ti–Zr–V films were prepared from an alloy target using the same DC magnetron sputtering parameters. The compositions and corresponding chemical bonding states were analyzed by X-ray photoelectron spectroscopy after activation at different temperatures. The test particle Monte Carlo (TPMC) method was used to measure the sticking probability of the Ti–Zr–V film based on pressure readings during gas injection. The results indicate that activation commences at temperatures as low as 150 °C and Ti0, Zr0, and V0 exist on the surface after annealing at 180 °C for 1 h. Ti–Zr–V films can be fully activated at 180 °C for 24 h. The CO sticking probability reaches 0.15, with a pumping capacity of 1 monolayer.