Pumping Characteristics of N₂ by Non-Evaporable Getter Pumps

Non-evaporable getter pump (NEG) is a vacuum pump made of the sorption characteristics of transition group metal materials, which is used for obtaining ultra-high/extremely high vacuum environments and gas purification. In this paper, a performance test system for getter pump is developed, the pumping characteristics of non-evaporable getter pump for N₂ gas are studied, and the factors affecting the pumping performance are analyzed. The developed system adopts the standard flow method to test the pumping speed, and provides (10⁻⁵~10⁻⁸) Pam³/s standard gas flow rate by constant conductance flowmeter, which can achieve pumping speed test under the gas pressure of (10⁻²~10⁻⁵) Pa obtained in the test chamber. The experimental results show that the NEG pump is in the best pumping state after activation, and when the pumping speed decreases, it can be placed under ultra-high vacuum conditions for a period of time to restore the pumping speed to the initial state, but the overall pumping performance of the pump changes to a certain extent. When the pump continuously pumps, the pumping speed gradually decreases with the increase of sorbed quantity, and decreases with the increase of test chamber pressure.