Protection system for the superconducting coils in WENDELSTEIN 7-X

Apart from scientific aims, an important technical goal of WENDELSTEIN 7-X is to demonstrate stationary operation. This is a fundamental fusion-reactor requirement and a characteristic advantage of stellarators over tokamak fusion reactors. Magnetic confinement is achieved by means of 70 coils with a diameter of up to 5 m and a magnetic induction of up to 3 T on the axis. To allow continuous operation, the coil windings are made of superconducting material. Because of the great amount of stored magnetic field energy of up to 1 GJ, the protection system is an essential part of the power supply system. This text describes the protection system for the superconducting coils as well as key preliminary experiments which demonstrate the suitability of selected components of the protection system for the WENDELSTEIN 7-X experiment.