Performance and Analysis of No-Insulation HTS Toroidal Magnet

As Tokamak toroidal field (TF) coils operate at a high magnetic field and experience a variety of transient heating loads, the applicability of no-insulation (NI) techniques to wind the TF coil is taken into consideration here in an effort to secure high current density and high thermal stability. This paper presents the construction and test results of a NI high temperature superconducting (HTS) toroidal magnet. We fabricated the magnet using BSCCO wire manufactured by Sumitomo. The magnet consists of ten racetrack double pancake (DP) coils. Each DP coil was tested separately in liquid nitrogen at 77 K to obtain its critical current and characteristic resistance, then, after assembly and soldering, the magnet was tested at 77 K to measure the variations in voltage and magnetic field during charging, discharging, and current disturbancing. Finally, we discuss the thermal runaway behavior of the toroidal magnet during overcurrent operation as well as the influence of the quenched coil on the other coils in the system.