Development and quench-training performance evaluation of the world’s largest aperture superconducting magnet with zero-evaporation for the SWORD

Abstract Mastering plasma–material interactions is critical for obtaining a high-performance and high-duty cycle fusion reactor. The requirements for the construction of a magnetized, steady-state, large-area, high-flux plasma generator necessitate the application of superconducting coils. At present, DIFFER’s main experiment, Magnum-PSl (MAgnetized plasma Generator and NUMerical modeling for Plasma Surface Interactions), stands as the world’s only facility capable of exposing materials to plasma conditions similar to those of future fusion reactors. This facility relies on a superconducting magnet system, which consists of five superconducting solenoids wound on a 2.5 m-long stainless-steel coil former. It can generate a magnetic field of 2.5 T, with a 1.01 m warm bore. ORNL’s main experiment, MPEX (The Materials Plasma Exposure eXperiment), is a superconducting linear plasma device consisting of six independent units. MPEX has developed a superconducting magnet system with warm bore diameters of either 0.65 m or 1.56 m, capable of operating at both 1.25 and 2.5 T. ASIPP’s main experiment, SWORD (Superconducting plasma Wall interactiOn lineaR Device), represents the world’s highest-parameter steady-state linear plasma generator, capable of producing plasma that closely resembles the boundary parameters of fusion reactors, primarily for materials research and lifetime testing. The device is equipped with a superconducting magnet with a magnetic field of 3 T, warm bore diameter of 1200 mm, and length of 2 m to ensure effective confinement of the high-performance plasma. This paper discusses key technical issues in the development of superconducting magnets for SWORD, including high-precision coil winding design, curing processes for large-diameter insulation materials, and stress distribution and regulation under high-current conditions. Additionally, the research details the establishment of an efficient cryogenic cooling system and a reliable energy release control method during quench-training tests, resulting in enhanced excitation performance and strategies for long-term stable operation of superconducting magnets in a zero-evaporation cryogenic system.