Thermal-Hydraulic Analysis of the Low-T-c Superconductor (LTS) Winding Pack Design Concepts for the DEMO Toroidal Field (TF) Coil

Three design concepts, namely, WP#1, WP#2, and WP#3, for the low-T-c superconductor DEMO toroidal field coil was proposed in 2014. This paper is focused on the thermal-hydraulic analysis of all the designs using simplified models, which includes: 1) hydraulic analysis-calculation of the mass flow rates in each conductor at operating conditions during the dwell time; 2) heat removal analysis-calculation of the steady-state mass flow rates and temperature profiles in each conductor as functions of the nuclear heat deposition rate; and 3) estimation of the maximum quench temperature and pressure in each conductor assuming the extreme scenario for the maximum pressure. The detailed analysis of the WP#1 design in burn and in quench conditions using the THEA code was also carried out. It took into account the expected electromagnetic and heat load maps along each conductor and different quench initiation scenarios leading to the maximum hot spot temperature or to the maximum pressure. Our analysis shows that the temperature margin in the WP#1 andWP#3 conductors is sufficiently large, but it is too small in some WP#2 conductors. The hot spot temperatures in some WP#1 cables calculated with THEA are too high. These results provide information for further improvements of the conductors' design.