Synthesis and Characterisation of Non-Evaporable Getter Films Based on Ti, Zr and V

Abstract: Non-evaporable getters (NEG) are widely used in ultra high vacuum (UHV) systems for particle accelerators to assure distributed pumping speed. By heating the NEG to an activation temperature, the oxide layer on the surface dissolves into the material, leaving a clean (activated) surface. The activated NEG surface is capable of chemisorbing most of the residual gases present in a UHV system and will act as a vacuum pump. NEG can be sputter deposited on the inner wall of vacuum chambers, turning the whole wall from a source of gas into a pump. At the largest particle accelerator in the world, the Large Hadron Collider, more than 6 km of beam pipe has been NEG coated. In this work, a DC magnetron sputtering system dedicated for coating cylindrical vacuum chambers with NEG has been assembled, installed and commissioned. The system has been used to do NEG depositions on inner walls of vacuum chambers. The vacuum performance of the coating has been measured in terms of pumping speed, electron stimulated desorption and activation temperature. In addition, the thin film composition and morphology has been investigated by scanning electron microscopy (SEM). The work has resulted in an operational DC magnetron sputtering system, which can be used for further studies of NEG materials and compositions.