Design and construction of the superconducting bus system for the stellarator W7-X

In the framework of cooperation between the Max-Planck-Institute for Plasma Physics (IPP) essential work packages of the superconducting stellarator Wendelstein 7-X (which is presently under construction at Greifswald, Germany) have been taken over by the Forschungszentrum Jülich (FZJ). One of these packages is the design, construction and manufacturing of the superconducting three-dimensional coil interconnections (the so called bus system) and its appropriate supports. Key task was the development and qualification of an appropriate insulation fulfilling not only the electrical requirements but also withstanding all mechanical stresses during operation. An overall concept of the project was elaborated with the goal to optimize working steps and to simplify the system assembly. In order to compensate the magnetic stray fields generated by the bus currents an appropriate bus topology was developed. No collisions with other parts, reduced space for integration and easy transportation were provided (Fig. 1).