Controllable rectification on the irreversible strain limit of 2G HTS coated conductors

Abstract

The second generation high-temperature superconducting coated conductors (CCs) have excellent electrical and mechanical properties, and are extensively used in superconducting devices such as fault current limiters, magnets and motors. During the operation of these superconducting devices, superconducting CCs inevitably bear the combination of electromagnetic force and thermal mismatch stress, resulting in straining of YBa2Cu3O7− δ (YBCO) layer along the tape length. It is well known that the strains of superconducting CCs cause degradation of critical current (I c). Generally, the irreversible strain limit ( ε irr ) is used to characterize the phenomenon that I c of superconducting CCs degrades with axial strain. When the axial strain of superconducting CCs is less than ε irr , I c can be reversibly recovered by over 99% after being unloaded. Therefore, ε irr is a key parameter for the design and application of superconducting CC devices. For this reason, to carry out a practical engineering method for improving ε irr of superconducting CCs has become a challenge and aroused interests among researchers. This study is based on the idea of precompression. A 316LN stainless steel tape was pretensioned at 77 K to improve its elastic strain limit. Then, two superconducting CCs were soldered onto both surfaces of pretensioned stainless steel tape respectively. As a result, ε irr of the superconducting CCs can be controlled manually with different precompressions. Taking YBCO CCs produced by SuperPower Inc. as an example, the measurement results show that the ε irr of the YBCO CCs increased from 0.39% to 0.73%. Meanwhile, the thickness of the sample did not increase more than once.

Temperature calibration of sample rods for neutron diffraction apparatus in the range of 6–473 K

“…The cryocooler ( 1) is responsible for providing the cooling capacity. The vacuum chamber (2) integrates the electrical interface (3) and bellows section (7) to create a high vacuum environment and accommodate the potential displacement of the tension rod (6) under a maximum load of 50 kN. The vacuum vessel includes aluminum windows to access the incident and diffraction neutrons.…”

“…In previous applications, a vertical stretching device was specifically designed to investigate the irreversible strain limit of 2 G HTS coated conductors [7]. Moreover, researchers explored strain characteristics in discontinuous plastic flow by utilizing liquid helium to achieve a lower temperature.…”

HTS conductor coil by in-situ winding technology for large-scale high-field magnet

“…In the design of HTS conductors for fusion reactors, however, the problem of stress concentration caused by the winding method and manufacturing process is always an urgent problem. When making HTS conductors, the winding stress will lead to a series of problems, such as the attenuation of critical current, the local quench of the coil, and the increase of loss, which will have a significant adverse effect on the device [32][33][34][35].…”

Enhancing the irreversible strain limit of Fe-base coated conductors for high-field magnets

“…It greatly increased the ε irr , but would increase the thickness of the sample [9-13]. Especially, Su et al [14] proposed a method to increase the ε irr with prestress. The 316LN stainless steel tape was pretensioned and soldered with two YBCO CCs on each surface.…”