학술논문

Design, Fabrication, and Assembly of the SPARC Toroidal Field Model Coil
Document Type
Periodical
Source
IEEE Transactions on Applied Superconductivity IEEE Trans. Appl. Supercond. Applied Superconductivity, IEEE Transactions on. 34(2):1-15 Mar, 2024
Subject
Fields, Waves and Electromagnetics
Engineered Materials, Dielectrics and Plasmas
Superconducting magnets
Magnetic confinement
Toroidal magnetic fields
Magnetomechanical effects
Windings
Magnetic resonance
Magnetic flux
Fusion energy
high-temperature superconductor
SPARC
superconducting magnet
toroidal field model coil (TFMC)
Language
ISSN
1051-8223
1558-2515
2378-7074
Abstract
The SPARC Toroidal Field Model Coil (TFMC) is the first large-scale (∼3 m), high-field (∼20 T) superconducting fusion magnet based on Rare Earth Yttrium Barium Copper Oxide (REBCO). Weighing 10,058 kg and utilizing 270 km of REBCO, the TFMC is a non-insulated, stack-in-plate style superconducting magnet. It has three main components: (1) the winding pack; (2) the structural case; and (3) the case extensions, or plena. The winding pack is composed of sixteen single pancakes with two termination plates top and bottom. The pancakes are Nitronic 40 radial plates machined with spiral channels on one side for the REBCO tape stack and single-pass channels on the opposite side for supercritical helium coolant. After assembly, each pancake undergoes a vacuum-pressure impregnation solder process to provide good mechanical protection of the REBCO tape stack and efficient thermal and electrical connectivity within each pancake. The pancakes are bolted along the inner and outer perimeter to provide mechanical and thermal connectivity while inter-pancake joints provide low resistance current transfer between pancakes. The top and bottom termination plates facilitate electrical connection to a superconducting feeder system. Embedded throughout the winding pack are 211 voltage taps, 34 temperature sensors, 34 helium flow monitors, 4 Hall probes, and 4 resistive surface heaters. The winding pack is contained within a structural case, a “trough and lid” style design composed of two Nitronic 50 forgings machined to shape and bolted together. The case reacts the large electromechanical stresses approaching 1 GPa during operation and serves as a pressure vessel that enables 20 bar supercritical helium flow that cools the winding pack and case. Two case extensions are attached to the case with unique high-pressure feedthroughs to provide winding pack access for current, cooling, and instrumentation, completing the magnet assembly.