A Global Structural and Electromagnetic Finite Element Model for the Prediction of the Mechanical Behavior of the JT-60SA Superconducting Magnet System

The JT-60SA is a fusion experiment designed to contribute to the early realization of fusion energy by providing support to the operation of ITER; by addressing key physics issues for ITER and DEMO; and by investigating how best to optimize the operation of the next fusion devices that will be built after ITER. It is a combined project of the JA-EU Satellite Tokamak Program under the Broader Approach (BA) Program and JAEA's Program for National Use, and it is to be built in Naka, Japan, using the infrastructure of the existing JT-60U experiment. The superconducting magnet system of JT-60SA consists of a Central Solenoid, six Equilibrium Field coils and eighteen Toroidal Field coils. The systems are connected to each other by means of flexible and kinematic mechanical attachments, with the Toroidal Field magnet acting as the structural backbone of the whole magnet system. This is then supported to the cryostat base of the machine through a series of gravity supports. A detailed finite element model, representing a 40 degree sector of the superconducting magnet system of JT-60SA, has been developed with particular focus on the mechanical connections between the different coil systems. A complete set of analyses were carried out to obtain the electromagnetic force distribution on the three magnet sub-systems during all operational scenarios and consequently to predict the corresponding stresses and deformations. By doing this the integrity of the system and the performance of its bolted and pinned connections were verified against the applicable codes and standards. This paper illustrates the details of the modeling strategy which lead to the production of the finite element model and provides a comprehensive report and a critical analysis of the most relevant results obtained to date.