Conceptual Design Study of a Test Facility Magnet for Fusion Conductor Samples

Design studies of the steady-state Korean fusion demonstration reactor (K-DEMO) magnet system have been conducted since 2013. The maximum magnetic field of the K-DEMO toroidal field (TF) coil is expected to be over 16 T. A high field superconducting magnet and a facility for testing the K-DEMO TF conductor samples are also being designed to prepare for the development of the K-DEMO TF conductor. To test straight fusion conductor samples compatible with the K-DEMO TF conductor, it is essential to have a large, 150 mm wide by 120 mm high sample space in the magnet. The required maximum magnetic field of the fusion conductor test magnet is expected to be over 15 T. The field consists of about a 15 T background field and some self-field. Both high current density Nb ₃ Sn strands and high temperature superconductor (HTS) tapes are candidates for the superconducting materials for the magnet. In this work, two conceptual design study models of the high field magnet are introduced - a planar racetrack dipole based on HTS tape (I _c > 200 A/4-mm at 4.2 K, 18 T) cable-in-conduit conductor (CICC), and a non-planar flared end saddle dipole based on Nb ₃ Sn strand (J _c > 2600 A/mm ² at 4.2 K, 12 T) CICC. 2-dimensional magnetic and mechanical analyses of both magnet models were performed and the main features of the models are presented.