Evaluating Conductor Design and Stability Performance for the Conductor of High-Field Winding Package in CFETR TF Coil

CFETR, also known as the China Fusion Engineering Test Reactor, is a significant undertaking planned by the Chinese government. This project serves as a bridge between ITER and DEMO, based on the experience from Experimental Advanced Superconducting Tokamak and ITER. The magnet system of CFETR consists of 16 toroidal field (TF) coils, eight central solenoid coils, and seven poloidal field coils. The dimensions of the TF coil of CFETR are 21.7 m in height and 12.3 m in width, which makes it a big challenge in manufacturing. During operation, various disruptions may occur, leading to instability in the conductors. To ensure sufficient stability against these disruptions, the CFETR TF coil has been meticulously designed. The TF magnets operate at a current of 95,600 A/turn to generate a 6.5 T field at the plasma centre. The peak magnetic field on the coil reaches 14.43 T, and the maximum stress exceeds 700 MPa. The winding package (WP) of CFETR TF coil was winded by cable-in-conduit conductor and graded into three sub-WPs based on the magnetic field, high-Jc Nb
₃
Sn strand is applied for the high-field sub-WP, and ITER type Nb
₃
Sn strand and NbTi strand are applied in mid and low field sub-WPs, respectively. Stability and quench analysis of the TF coil system in CFETR have been performed. This analysis utilizes the 1-D code “GANDALF.” The stability simulations consider multiple scenarios applied to the superconducting cable during the most critical operating conditions to thoroughly examine the minimum quench energy and temperature margin against short-term mechanical and long-term electromagnetic disturbances.