Effect of the film thickness on pumping properties of Ti–Zr–V coating

Non-evaporable getter (NEG) coating is widely used for vacuum system of charged particle accelerators. The RF surface resistance of NEG coating is increasing with its thickness. Therefore, knowing how NEG coating properties depend on its thickness is essential for vacuum system design of accelerators. This paper describes the results of studying the pumping properties of Ti–Zr–V NEG films deposited from an alloy target for thicknesses in the range between 0.1 and 1μm. Good pumping properties for H2 and CO have been demonstrated after activation to 140 °C. It has been demonstrated that initial CO sticking probability does not depend on thickness, however, initial H2 sticking probability and CO sorption capacity are almost proportional to NEG thickness. The NEG coating degradation with a number of activations has been observed, the thinner NEG film the stronger the degradation.