The characteristics of a Zr-V-Fe non-evaporable getter as a vacuum pump for the accelerator

This paper reports on a non-evaporable getter (NEG) that can be manufactured in both linearly-distributed and lumped shapes for particle accelerators including storage rings to provide a high pumping speed and large capacity in a simple, cheap and flexible way. Zr-V-Fe (St 707) NEG strips and wafers are under consideration to be used as the main pumps in both straight-section and bending-magnet chambers, and crotches, respectively, of Spring-8. The characteristics of this ST 707 is not known yet in detail even if commercially available and a few works reported recently. The authors present the experimental characteristics at room temperature of the St 707 NEG strip and wafer in mind for their ring. The work includes a series of the measurement results of the total and specific pumping speed (S and s) with respect to the gases such as H2, Co, N2 and CO2. The specific gas quantity sorbed (Q) is from as small as ∼2 x 10-5 to 2 x 10-3 Torr · 1/cm2 for strip total gas quantity sorbed (Qa) from ∼1 x 10-5 to 3 Torr · 1 for wafer. The authors also demonstrate the dependence of pumping speeds of H2 and CO on the parameters such as initial gas loading (Qo), gas injection rate (q), and reactivation temperature (Tact) and time (tact)