Status of the Project: New Upper Divertor With Coils in ASDEX Upgrade

ASDEX Upgrade (AUG) is the German mid-size Tokamak with the aim to exploit the physics baseline of the future fusion devices. Since August 2022 AUG is in maintenance phase to allow, among others, the installation of the new upper divertor including two concentric coils. Theoretical detachment studies have shown a mitigation of the exhaust power problem with alternative divertor configurations, realized with two coils positioned in the outer strike line of the divertor. The coil conductor has been custom-made for our application and has been extensively tested and stressed in previous years. The main peculiarity of these coils is that they are wound from a single unit length of conductor without any internal electrical joint to reduce the risk of failures. This design choice involves a considerable effort to wind the coils inside the much-populated vessel of an experimental machine. A complex bending procedure has devised considering the tight space available inside the AUG vessel. The procedure is based on the deployment of a fully automated winding machine and only for the realization of the termination manual bending will be adopted, assisted by accurate metrology. To mitigate the risks and to train the work-force, the winding machine is commissioned using a 1:1 mechanical twin of the AUG vacuum vessel. This mock-up has been built by reverse engineering of the existing experimental vessel. Currently, the commissioning of the system is ongoing. The present paper provides a description of the processes involved and reports the current status of the activities.