Conceptual Design of Pumping Systems up to 1000 m3/s Based on Non-Evaporable Getters in a Gas-Dynamic Magnetic Trap

Abstract

The Gas-Dynamic Magnetic Trap (GDMT), a new linear magnetic facility for confining high-temperature hydrogen plasma, is currently under development at the Budker Institute of Nuclear Physics (BINP SB RAS). The total hydrogen flow that must be removed from the end expanders by the vacuum system is approximately 10^22 molecules/s, which corresponds to a required pumping speed on the order of 500 m3/s. Non-evaporable getters (NEG) are considered as a possible pumping method for this application. This article presents experimental studies of Ti-Zr-Al getters manufactured by Polema LLC. The pumping speed, sorption capacity, and sticking factors of the getter surface were measured. The sticking factors for hydrogen and deuterium are 2.23% and 1.54%, respectively. The getter pumping speed is maintained over 60 air-vent/reactivation cycles. Based on these results, a conceptual design of a NEG-based pumping system for the GDMT end expanders is proposed, providing a specific pumping speed of 74 m3/(m3s) for the getter panel. The proposed pumping system design and the required heating power are discussed.