Construction and assembly of WENDELSTEIN 7-X

WENDELSTEIN 7-X (W7-X) is an optimised stellarator which shall demonstrate the reactor relevance of the HELIAS type magnetic configuration. The magnet configuration is produced by a set of 50 non-planar and 20 planar superconducting coils. These coils allow varying the magnetic configuration and studying the plasma in a wide range of parameters. The coil system is supported by a massive support structure and thermally protected by a cryostat.Many components of W7-X are in an advanced stage of construction and several of the main components have been delivered. Following comprehensive trials to ensure that the specified accuracy can be met, assembly has started in April 2005.The paper describes the status of construction and assembly and focuses on lessons learned during fabrication of the components.