Design Optimization for Shear Key on the TF Coil Structure of the KSTAR Tokamak

Abstract

The KSTAR tokamak is comprised of a magnet system, vacuum vessel, and cryostat, thereby facilitating vacuum conditions for plasma gas at high temperatures, along with low-temperature helium gas for cooling. The TF coil structure, a part of the magnet system, is constructed and jointed with 16 pieces at 22.5-degree intervals using a conical bolt and shear key. The main function of the shear key in the inner and outer inter-coil structures is to resist in-plane and out-of-plane forces and to increase the shear stiffness for the inter coil structures. However, since the shape of the shear key is difficult to produce and can incur high costs, the shear key needs to be dimensionally optimized to regularize the stress between the key and the structure. Accordingly, shape optimization of the shear key was carried out using the Taguchi method and the stresses analyzed by ANSYS.