DEPOSITION OF NON EVAPORABLE GETTER (NEG) FILMS ON VACUUM CHAMBERS FOR HIGH ENERGY MACHINES AND SYNCHROTRON RADIATION SOURCES

摘要

Non Evaporable Getter (NEG) films, sputter deposited onto the internal surfaces of vacuum chambers reduce thermal out-gassing and provide conductance-free distributed pumping ability, allowing the achievement of very low pressure inside narrow and conductance limited chambers, like Insertion Devices. NEG films do show additional interesting features, like low secondary electron yield and low gas desorption rates under ions, electrons and photons bombardment. They seem therefore ideal to reduce electron multi- pacting and dynamic gas desorption induced beam instabilities in high energy machines. This paper presents SAES Getters' experience in the NEG coating of chambers of different geometries and sizes for a variety of projects related to high energy machines and synchrotron radiation facilities. Examples of applications, as well as most common issues related to chambers preparation, film deposition, characterization and quality control, are given. Areas where further work is still necessary to fully take advantage of NEG film properties will be also discussed.