Development of a Displacement Measurement System for Wendelstein 7-X Superconducting Magnet System

The superconducting magnet system of the Wendelstein 7-X (W7-X) stellarator fusion experiment consists of 50 nonplanar and 20 planar coils. During the operation, the W7-X stellarator will produce a magnetic field strength of 3 T in the plasma center, and it will also bring very high electromagnetic forces in the coils and their related mechanical support structures. In order to ensure the mechanical integrity of the superconducting magnet system, 70 devices of a displacement measurement system are being installed to monitor the coil displacement. In this paper, the development of the displacement measurement system and the first measurement results performed on a W7-X superconducting planar coil are presented.