Design, commissioning, and first operation of the high-temperature superconducting tokamak Honghuang70

• Honghuang 70 is the world’s first full high-temperature superconducting tokamak. • Designed, constructed, commissioned, and operated in 24 months. • High-temperature superconducting TF, CS, and PF coils operate at 20 K. • Results from integrated commissioning verify engineering design. • First plasma achieved in June 2024. Honghuang70 (HH70) is the world’s first fully high-temperature superconducting (HTS) tokamak. It is a medium-sized tokamak with modest aspect ratio, featuring a major radius of R 0 = 0.7 m and a minor radius a = 0.25 - 0.3 m. At the designed coil operation temperature of 20 K, the maximum designed magnetic field on the magnet coils is B max = 2.5 T, and the toroidal magnetic field at the plasma center B 0 = 0.6 T. All of HH70’s coils including the central solenoid (CS), the poloidal field (PF) coils and the toroidal field (TF) coils are constructed with the rare-earth barium copper oxide (ReBCO) HTS tape as the main current-carrying component. The construction and assembly of HH70 were completed in 2024. The coil commissioning results show that the behavior of the HTS coils agrees with engineering simulation results. The integrated commissioning has verified the capability of the supporting subsystems. This paper reviews the design, assembly, commissioning and initial operation of the HH70 tokamak, including its HTS coils and main supporting systems. The successful operation of HH70 demonstrates the feasibility of full-HTS tokamaks and provides valuable engineering experience.