Helium Refrigeration System for Wendelstein 7-X

Publisher Summary This chapter gives an overview on the cooling requirements as well as on the refrigeration system chosen for the superconducting magnet system and cryo vacuum pumps of WENDELSTEIN 7-X, a new fusion experiment of the stellarator type. A flexible refrigerator was developed which is able to run in quite different working conditions. Special features are single phase forced flow cooling with adjustable supply temperatures down to 3.4 K using cold circulators and cold compressors. The various operating modes, combined with the requirement to limit the power input, day-night load leveling, and the spatial boundary conditions for the system layout were a challenge for process and construction designers. With the W7-X refrigerator, Linde Kryotechnik AG and the Max Planck Institute for Plasma Physics broke new grounds. With the well directed use of the cold buffer as well as the extremely optimized sub-cooling system the refrigerator will save costs and energy. Because of the application of cold compressors and time distributed loads the warm compressor system will be comparably small. Apart from saving costs, space within the buildings is saved as well.