Distributed Pumping by Non-Evaporable Getters in Particle Accelerators

Distributed pumping in particle accelerators has recently been proposed as an interesting approach to maximize the pumping efficiency inside the chambers. The distributed pumping can mainly be performed by ion pumping structures or by non-evaporable getter devices arranged along the inner walls of the chambers. The non evaporable getter approach, which appears to have very promising technical and economical impact, is considered and discussed. In particular reference is made to the use of non-magnetic strip coated with both high temperature (700-800°C) activatable getter materials and low temperature (less than 500° C) activat able getter materials of more recent development. The sorption characteristics of these getter coated strips are reported for the most important gases after efficient activation. The results show the possibility of attaining high "linear" pumping speeds, ie. as high as a few hundred liters per second per meter of chamber length for hydrogen. The suitable modes of operation of the getter coated strips for this specific application are also discussed together with the preliminary results of the practical embodiment of this approach.