Chemical pumping, also known as gettering, is a smart way to get a vacuum in a wide variety of vacuum systems and devices. Compared to other pumping means, getter devices do present several interesting features which make them ideal in a number of UHV or XHV applications. Getter pumps are very compact and lightweight and operate also during power outage. They have better affinity for hydrogen than turbo-molecular or sputter ion pumps and their efficiency is not reduced with decreasing pressures. Getter pumps are vibration free, unaffected by magnetic fields and do not generate magnetic fields.
Chemical pumping in large vacuum systems was pioneered in the eighties for the LEP collider at CERN, where 27 km of non evaporable getter strip were used to keep 10-11 mbar range during machine operation.
Since then, Non Evaporable Getters (NEGs) have been extensively used in a variety of machines requiring UHV-XHV levels such as nuclear fusion equipments, particle accelerators or synchrotron radiation light sources. Physics experiments, like the KATRIN project for neutrino mass detection, requiring challenging vacuum requirements in very large vessels, are also benefiting from getter technology.
More recently, a new way to integrate chemical pumping in particle accelerator vacuum chambers was developed at CERN for the LHC collider. Sputtering thin film of NEG onto the internal surface of a vacuum chamber converts an outgassing source into a vacuum pump. The getter film also provides better surface properties in term of reduced out-gassing rates under ion, photon or electron bombardment and secondary electron emission. After extensive laboratory testing, this technology is now being adopted in an increasing number of high energy machines, where it delivers superior vacuum properties and allows machine re-design and simplification.
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