As an important component of Negative ion based Neutral Beam Injector (NNBI). the cryopump mainly provides a suitable vacuum environment for beam generation and transmission. In the paper. Liquid nitrogen (LN2) pipe structure models of two cryopumps were established for simulation and experimental studies. https://www.bekindtopets.com/flash-grab-Viqua-F4-Ultraviolet-Water-System-Powered-by-UVMax-36-gpm-top-savings/