Construction of the vacuum vessels and the magnet supporting structures of Wendelstein 7-X

The superconducting magnet system of the Wendelstein 7-X Stellarator and its supporting mechanical structures are placed between two vacuum vessels. The inner plasma vessel encloses and follows the shape of the plasma. The toroidal outer vessel (OV) is the external boundary of the cryostat towards the environment. Two hundred and ninty-nine ports connect the internal components and the plasma chamber to the outside and the auxiliary devices. All the structures inside the two vessels are kept under high vacuum at 4 K. This paper describes the construction activities of the vacuum vessels and the magnet supporting structures.