Preliminary design and structural assessment of DTT in-vessel coil supports

The present work regards the design methodologies for a crucial component of the new thermonuclear fusion energy machine named "Divertor Tokamak Test facility" (DTT). The purpose of this experimental facility is the investigation of the thermal exhaust issue, a critical aspect in the view of DEMO construction, and future nuclear fusion reactors for commercial use. The construction of DTT machine is starting in the ENEA Site, Frascati, Italy. The poloidal magnet system in the proposed DTT includes a central solenoid divided into 6 independent modules, plus 6 external coils. The poloidal field system also includes six copper in-vessel coils, namely two in-vessel coils for radial and vertical plasma stabilization and control, and four out of six in-vessel divertor coils for magnetic control of scrape-off layer and strike point sweeping. This work aims to provide a preliminary design of the supports for the 6 in-vessel coils considering the Electromagnetic (EM) loads due to a plasma Downward (DW) Vertical Displacement Event (VDE) at the flat-top of plasma reference single null scenario. During a DW VDE a huge amount of current flows in the in-vessel coils (circumferential direction), whose interaction with the poloidal EM field generates strong EM forces. The electromagnetic loads have been calculated with MAXFEA, a two-dimensional finite elements code for the simulation of plasma equilibrium, and then applied to homogenized in-vessel coils in the structural analysis.