K. Rummel

Insulation of the Coil and Bus Bar Ends During Assemblyof W7-X

The superconducting magnet system of the WENDELSTEIN 7-X (W7-X) experiment consists of 50 nonplanar and 20 planar coils which are connected by 121 bus bars in series in seven groups of ten coils each. The terminal ends of the coils and bus bars are not insulated by the manufacturers and will be insulated during assembly. The insulation has to withstand a voltage of 13 kV dc for 1 min at Paschen conditions. Furthermore it has to be considered that the quench detection wires which were fed inside the insulation along the coil and bus bar ends have to be fed through the insulation near the joints

Experiences from the installation of the superconducting bus bar system of Wendelstein 7-X

The superconducting bus bar system of the Wendelstein 7-X (W7-X) experiment consists of 121 bus bars and 184 joints, which provide the electrical and hydraulical connection between bus bars and coils and between different bus bar sections. The bus bars are made of the same superconductor as the coils and were pre-bent, insulated and tested by the FZ Jülich. The assembly of the bus bars was a logistical and technical challenge because of numerous interfaces and geometrical boundary conditions. The complexity of installation required extensive quality assurance and assembly plans, where each work step had to be precisely defined. The assembly of all bus bars and joints has been finished. The installation of the current leads which connect the bus bar system to the power supplies is underway.

Installation of the Superconducting Bus Bar System of Wendelstein 7-X

The superconducting bus bar system of the Wendelstein 7-X (W7-X) experiment consists of 121 bus bars and 184 bus bar joints, which provide the electrical and hydraulical connections between bus bars and coils and between different bus bar sections. The bus bars are made of the same superconductor as the coils. The W7-X superconductor is made of 243 NbTi copper stabilized strands enclosed in an aluminum jacket. The bus bars were cut, bent, and partially insulated before they were delivered to the assembly area of W7-X. The assembly of the bus bars was a logistical and technical challenge because of numerous interfaces and geometrical boundary conditions. The complexity of installation required extensive quality assurance and assembly plans, where each work step had to be precisely defined. The assembly of all bus bars and bus bar joints has been finished. The installation of the current leads that connect the bus bar system to the power supplies is underway.

The Quench Detection-Wire-Feedthrough Plug-In of W7-X

The stellarator fusion experiment Wendelstein 7-X (W7-X) is presently under assembly at the Greifswald branch of the Max-Planck-Institut für Plasmaphysik (IPP), Germany. To allow the steady-state operation, W7-X has a superconducting magnet system. It consists of 50 non planar coils, 20 planar coils, a superconducting bus bar system and 14 current leads. For continuous on-line monitoring of the superconducting state 1624 Quench Detection-wires (QD-wires) are connected at the joints of the coils and the bus bars. The signals of these wires must be fed through the Outer Vessel (OV) shell to the Quench Detection Units. The electrical feedthroughs, wires and wire connections have been designed and qualified for a test voltage of 13 kV under low gas pressure (Paschen test). Other important requirements are a maximum allowed integral helium leak-rate of l/s per QD-dome and a maximum allowed total heat load to the thermal shield of the OV of 140 W per QD-dome. The paper describes the design and qualification of the QD-Wire-Feedthrough-Plug-in, the assembly procedure as well as the tests carried out during and after assembly.