Pumping performance analysis of negative ion based neutral beam injector cryosorption pump prototype

摘要

A cryosortion pump creates a vacuum gradient environment in the process of neutral beam generation and transmission. Its pumping performance is related to the neutral beam quality. Here, the structural design and manufacturing method of the cryosorption pump were demonstrated based on the actual needs of negative ion based neutral beam injector (NNBI).Then,in order to verify the rationality of cryosorption pump's design, the test system of the cryosorption pump test prototype was built based on the flow-meter method to perform experi-ments to study the factors affecting the pumping performance. The results show that the prototype's stable pumping performance under different temperature, vacuum pressure, gas composition and the important characteristics of effective pumping speed for hydrogen and its isotopic gasses. The maximum error between the actual and the theoretical pumping speeds is maintained within 35%. The physical mechanism that temperature fluctuation and impurity gas helium can obviously affect the pumping performance of the cryosorption pump is revealed.It is concluded that the cryosorption pump prototype has excellent pumping performance, verifying the rationality of the structural design and providing a reference for the performance evaluation of a NNBI cry-osorption pumps.

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