Assembly Status of the W7-X Stellarator

Wendelstein 7-X is a superconducting stellarator being constructed in Greifswald, Germany. The assembly of W7-X is now well underway with the delivery of the main components for the construction of the first module. The spiral shape of the stellarator vacuum vessel means the 70 coils must be threaded individually over the vacuum vessel. This has now been achieved using the foreseen 5 axis coil handling devices. The distance between the coils is fixed by a series of radial and lateral support elements, central support elements and planar support elements, the assembly technology has been tested by an extensive test programme, the first of these radial elements have been installed and the tight assembly tolerances for assembly maintained. W7-X is equipped with 299 ports for diagnostics and supply of in vessel components; they connect the ICRH, ECRH and neutral injection systems to the plasma vessel. All ports must be positioned accurately at various angles around the vacuum vessel, ranging in weight from 100 kg up to 900 kg. For the ports this requires close integration of the manufacturing, metrology and assembly technologies. The powered ramp and bridge structure are under construction and the welding technology for welding and leak testing the port/plasma vessel weld is qualified. Detailed studies for the in-vessel components including a test campaign using the actual plasma vessel sectors in planned for later this year. The adjustability of the divertor and baffle plus the required flexibility of water connections is under investigation. The bus bar system links all coils to the power supply system is in manufacture and assembly tests. Space constraints within the machine cryostat require compact super conducting joints which, have been designed and tested with a resistance in the range of 1nOhm are now in manufacture. The paper will give an overview of the assembly status of W7-X; outline the assembly problems on the various components and the foreseen solutions in order to bring the machine into operation.