Cryogenic Stability of LTS/HTS Hybrid Conductors

Abstract

Abstract-Hybrid-type superconductors are proposed by utilizing a bundle of high-temperature superconducting (HTS) tapes as a stabilizer of low-temperature superconducting (LTS) cables in order to extend the basic research on the cryogenic stability of solid composite-type superconductors and to explore its potential. Since the effective resistivity of HTS is significantly lower than that of pure metals of equivalent cross-sectional area, a bundle of HTS tapes may work as a good stabilizer to achieve high current density. Short sample experiments have been carried out by modifying the aluminum-stabilized superconductor used for the LHD helical coils and the cryogenic stability was examined.

Current distribution characteristics of NbTi/Bi2223 hybrid superconductor

“…But the superconducting magnets cooled by a cryogenic refrigerator without liquid helium have worse cryogenic stability and quicker quench propagation than directly immersed in liquid helium. In order to increase the operating current density and the stability of magnet, and meet the requirement of cryo-cooled technology, a new kind of LTS and HTS hybrid conductor was proposed and studied [2,4]. In this kind of hybrid superconductor, HTS partly replaces the metal stabilizer of LTS or combines with LTS.…”

“…I H , I L and I M are corresponding branch currents. Those parameters satisfy the following equation (1)[2,4], where U C =E C l. E C is the critical electric field (E C = E(I C )), and is usually equal to 1.0 μV/cm, l is the length of the hybrid superconductor. n H and n L are n values of HTS and…”

Characterization of a laboratory scale high-Tc‘D-shaped’ magnet

“…A few initiatives have been put forward for hybrid superconductors [12][13][14][15], using a low-temperature superconductor (LTS) and a high-temperature superconductor (HTS), as the base conductors for fusion applications. Since the high-field compatible A15 (Nb 3 Sn and Nb 3 Al)-based LTS materials are strain sensitive similarly to the HTS materials, the baseline behavior of HTS wound magnets alone at 77 K could help gain a better understanding of hybrid configurations.…”

Current distribution and stability of LTS/HTS hybrid superconducting conductors

“…NbTi superconductors with large current capacity (several tens of kA) utilized in large helical devices (LHD), a new LTS/HTS hybrid in which HTS is used as a stabilizer in place of low-resistivity metals, was proposed [2][3][4]. Thus its cryogenic stability against thermal disturbance, steady-state cold-end recovery currents and the minimum propagation currents (MPC) can be greatly improved because the HTS has very low resistance and current diffusion which is faster than that in a pure conventional conductor matrix.…”