Wendelstein 7-X trim coils — Component safety aspects and commissioning strategy

The stellarator fusion experiment Wendelstein 7-X (W7-X) is currently under construction at the Max-PlanckInstitut für Plasmaphysik in Greifswald (IPP), Germany. Five normal conducting trim coils have been designed to allow for fine tuning of the main magnetic field during plasma operation. To limit the mechanical stress in the coil the proper function of the coil cooling system must be carefully monitored. Two independent systems monitor the coil temperature. One system works with temperature sensors to control the cooling water temperature. The second system monitors the copper conductor temperatures by voltage readings. Additionally, flow monitors in the hydraulic outlet line of each coil determine if the required cooling water flow is present. The trim coil system will be provided as part of a collaboration program between the Princeton Plasma Physics Laboratory, Oak Ridge National Laboratory and the Wendelstein 7-X project, and is funded by the U.S. Department of Energy.