Conductor Design for Toroidal Field Coils of a High Magnetic Field Tokamak TRT20

Abstract

Recently, the developmentof the concept project of the high magnetic field (HMF) tokamak continues in the Russian Federation. The value of the magnetic field on the plasma axis in the device is about 8 T. The maximum field on the winding of the toroidal field coils is about 15 T. The creation of a high magnetic field in a limited space of tokamak-type device with a given aspect ratio-R/a≈3.77 (R = 2.15 m-the big radius of the tokamak, and a = 0.57-the “radius” of the plasma) leads to a significant increase in the engineering current density in the toroidal field coils. The mechanical stresses in the magnet increase accordingly. Acceptable from a technical point of view for protective energy output are the values of the maximum electrical voltage relative to the ground-U <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">max</sub> ≤+/−5 kV and the temperature in the “hot spot” - T <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">max</sub> ∼200 K. In addition, it is necessary to minimize heat losses in the stationary mode of operation of the tokamak, which significantly depend on the number of current leads used in the toroidal magnet. In this paper, we propose original possible solutions of the problems listed above. A “cable-in-conduit” type of conductor (CICC) is used in the TRT toroidal magnetic system. The cable portion of the conductor is manufactured from parallel non-transposed tapes of HTS REBCO coated conductor, which are oriented mainly parallel to the vector of the toroidal magnetic field. We call this design PaST (Parallel Stacked Tapes) conductors. The design of the conductor is developed to the requirements for a real device and differs from the previously proposed by more compact dimensions.