NONEVAPORABLE GETTER INVESTIGATION AT THE NATIONAL SYNCHROTRON LIGHT-SOURCE

We report H-2, CO, and CO2 pumping speed measurements on a linear pump using NEG strip St 707 (Saes Getters Inc.) as a function of both adsorbed gases and number of activations. To simulate the conditions of an operating storage ring a gas mixture of 50% H-2, 35% CO, and 15% CO2 is used in all measurements. Initial measured pumping speeds of > 450 lm-1 s-1 decrease to 200 and 100 lm-1 s-1 for H-2 and CO, respectively, after 70 air exposures. A further drop to 50 lm-1 s-1 for CO occurs at CO loading of 1 x 10(-2) Torr lm-1. CO2 and CO pumping speeds are about the same. The photon stimulated desorption for both baked and activated strips is an order of magnitude lower than that for stainless steel.