Recently, the first two-stack winding pack of the Jingtian magnet successfully passed the test. In this test, two single-pan ReBCO coils were stacked in series to form a two-stack winding pack, and a current of 31.4 KA (per turn) was passed through the winding pack via ReBCO current leads, which was maintained for 60 minutes. The purpose of this test was to verify the current-carrying capacity and other key parameters of the winding pack and current leads, as well as to conduct an integration test of auxiliary systems such as the cryogenic system, power supply system, and vacuum system.
Upon testing, the winding pack and current leads have achieved the designed values for their current-carrying capacity and other key parameters. Specifically, the winding pack amp-turns reached 755 KA-turns, the winding pack current density reached 204 MA/m2, the total resistance of the winding pack was below 12 nΩ, and the pan-to-pan joint resistance was below 5 nΩ, with all auxiliary systems operating normally. The test of the two-stack winding pack confirmed the reliability of the design and manufacturing process of the Jingtian magnet and validated the Energy Singularity team’s capabilities in designing and manufacturing large-bore high-field HTS magnets.
The Jingtian magnet is a large-bore high-field HTS toroidal field (TF) magnet developed by Energy Singularity. Its mission is to research, develop, and verify the key technologies and manufacturing processes needed for the TF magnets of the Energy Singularity’s next generation HH170 HTS tokamak. The Jingtian magnet is a D-shaped, non-insulated, stack-in-plate style HTS magnet, composed of 32 single-pan coils stacked together. The linear size of the winding pack of the magnet is approximately 1.9m * 1.3m, with a center bore of 0.5 m2. The conductor is made of ReBCO HTS tapes, and the plates are made of GY50G steel, and the coolant type is supercritical helium.
The Jingtian magnet is expected to be assembled by the end of this year, with its design objectives including: (1) peak field-on-conductor exceeding 25 Tesla; (2) winding pack current density exceeding 180 MA/m2. The structure, materials, processing, coolant type, and operating temperature of the Jingtian magnet are identical to those of the HH170 tokamak’s TF magnets, and key parameters such as peak field, current density, and peak Lorentz loading are not lower than what is required for the HH170 tokamak’s TF magnets.