Development of a copper coating suitable for application on the nonplanar W7-X coils

Following the design changes on the non planar W7-X coils, the foreseen coating by spot welding of copper plates can no longer be applied due to the shape of the cases. Therefore BNN investigated alternative methods, for example electro-plating and thermal spraying as well as an adaptation of the copper plating, and compared the advantages and disadvantages of the different solutions. For all methods, industrial feasibility was the basis of the investigation. Since thermal spraying seemed very promising, the low temperature properties of thermal sprayed copper were evaluated. Based on the results, a cooling system was decided on, where most of the surface is covered with sprayed copper. Additionally, copper strips shall ensure that sufficient cooling power can be deposited in the coil cases.