Superconducting joints between (RE)Ba2Cu3O7- coated conductors via electric field assisted processing

Project: Research project

Project Details

Description

high inductance can be particularly challenging for quench protection. The batch length of REBCO conductor available limits the length of cable that can be manufactured, thus the availability of superconducting joints may be enabling for large, cable-wound magnets. The development of superconducting joints for complex cables, however, is more challenging than the development of tape-to-tape joints. The limited space available, the need to maintain high engineering critical current density (JE) and the complexity of the geometries dictate that a joining technique be simple, reliable and readily reproducible.

We propose to use electric field assisted processing (EFP) to develop superconducting joints between REBCO conductors. In experiments with other materials systems, EFP has been shown to inhibit grain growth, clean the surface of grains to encourage intergranular contacts, improve the quality of interparticle bonds and allow for lower temperature atomic diffusion and defect motion. EFP has also been shown to prevent the formation of new phases and maintain anisotropy of the material being processed. EFP can be performed at or near room temperature, which aids in preventing oxygen loss in oxides. Thus, EFP is a particularly promising pathway to REBCO-REBCO superconducting joints. Furthermore, a recent preliminary experiment at NC State University has shown that EFP can cause diffusion bonding at a YBCO-YBCO interface and create a mechanically sound bond. Thus, we propose to build on this initial proof-of-concept experiment to investigate systematically EFP as an approach to creating high performance REBCO-REBCO superconducting joints.

The objective of this work is to develop a pathway to joining REBCO coated-conductors that is directly scalable to cables. In particular, a primary objective is to form superconducting joints with high JE using a simple, localized approach based upon EFP that does not require high temperatures. Additionally, we will develop an understanding of the relationships between EFP-microstructure-properties, including electrical, magnetic and mechanical behavior. The primary focus will be on high field transport and electromechanical behavior. By developing an understanding of the mechanisms and factors pertinent to improving behavior, we will subsequently improve the specific details of the EFP approach to further improve joint characteristics. This research will result in a dense superconducting joint which facilitates magnets requiring much longer lengths than the current batch-length limit to be built and operated in persistent mode, tape-to-tape and cable-to-cable connections, and magnet design flexibility through conductor grading.

Collaborative experiment: none.

StatusFinished
Effective start/end date5/1/143/31/17

Funding

  • High Energy Physics: $300,000.00

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