Pump, cryogenic mechanical vacuum

Six different types of pump are used to evacuate a vacuum system. The first and most common is the mechanical displacement pump [226,227]. The second is the vapour stream pump [228]. The third is the modem turbomolecular pump [229]. The fourth type is the chemical getter pump. The fifth is the ion pump and the sixth is the cryogenic pump [230]. In technical coating systems, the first three types of pump are preferred. The development of these pumps is narrowly associated with the names W. Gaede, I. Langmuir, C. Burch, K. Hickman and W. Becker [221,225]. Cryogenic pumps have also been used to evacuate technical coating plants. 

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