New approach to meet vacuum requirements in UHV/XHV systems by non evaporable Getter technology

Abstract

UHV/XHV users are increasingly demanding vacuum pumps with high performances with smaller package and weight. This requires a more efficient combination/integration of the currently available pumping technologies and, possibly, the development of new approaches in vacuum pumping systems. Non Evaporable Getter (NEG) pumps represent one of the most appealing option to UHV/XHV pumping, thanks to his large pumping speed and sorption capacity for several active gases (H2, H2O, CO, O2, N 2, ...). NEG pumps can also reduce the pump down and bake-out time and can keep a stable pressure level in UHV conditions even if the other pumping systems are switched off. However, NEG pumps are unable to sorb, in UHV/XHV systems, the small amount of noble gases and methane which, on the other hand, can be removed by sputter ion pump (SIP). For this reason, extensive studies have been carried out to combine NEG and SIP technologies. Some results of the vacuum characterization of such combination are discussed in this work and compared with traditional pumping approaches based on large SIP. A further step forward is the NEXTorr®3 pump which is an integration of a NEG pump (pumping speed ranging between 100 to 500 l/s for hydrogen) with a SIP (pumping speed of 6 and 10 l/s for Ar and CH4 respectively) into a single small package unit. Examples of applications of this new approach in vacuum technology will be given to demonstrate the simplification of the design and operation of UHV/XHV systems.