Thermostructural Analysis of Large Cryopumping Test Facility

To create high and ultra-high vacuum environments in large-size chambers for applications in space research, nuclear fusion, accelerators, etc., vacuum pumps with fast pumping speeds are essentially required. To cater to this need, one promising solution is the cryopump, which offers efficiency, a low cost, and applicability. The Institute for Plasma Research is working to develop large-size cryopumps and to develop performance testing and design validation for such cryopumps. In this paper, the Large Cryopumping Test Facility (LCTF) is conceptualized. It houses a large cryopump designed to achieve the pumping speed of similar to 50 000 L/s for nitrogen gas. The LCTF includes a dome chamber to make the pumping speed measurements per the American Vacuum Society standard and a hybrid cryopump with a 1250-mm opening diameter. The present work illustrates the configuration of the cryopump and its subsystems. The pump will be cooled by liquid nitrogen (LN2) to an 80-K temperature and a Gifford-McMahon cryocooler for up to a 10-K temperature. Here, a new geometrical concept for the pump is considered where the annulus LN2 bath cools the array panels and baffles and also acts as a radiation shield to protect the 10-K cryopanels from radiation heat load. A detailed investigation of the thermal and structural analysis for the LCTF is discussed to validate the performance of the pump and the robustness of the system.