REBCO Superconductor Tape Stack for Current Sharing and NZP
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Solution Overview
Problem
High Temperature Superconductor (HTS) materials like REBCO tapes face challenges with Normal Zone Propagation (NZP) velocity being significantly lower than Low Temperature Superconductors, leading to slow-spreading normal zones and potential thermal runaway due to defects and hot spots, which are difficult to detect.
Innovation Solution
The development of superconductor tape stacks with improved current sharing characteristics, including face-to-back configurations, conductive substrates, slotted superconductor films, and conductive buffer layers, along with thicker stabilizer layers and conductive materials to enhance current flow and defect management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If REBCO tapes are used to operate at higher temperatures and magnetic fields, then the operating temperature and magnetic field capability are improved, but the Normal Zone Propagation velocity becomes significantly lower leading to slow-spreading normal zones and potential thermal runaway
Solution Approach 1:
The tape is segmented into multiple parallel superconductor layers separated by conductive buffer layers. This segmentation allows the normal zone to spread across multiple layers through the conductive buffer, effectively increasing the NZP velocity and preventing localized thermal runaway while maintaining the high temperature and magnetic field operating capabilities of REBCO
Solution Approach 2:
Conductive buffer layers are introduced as intermediary elements between superconductor layers. These buffer layers facilitate heat and current distribution across the tape structure, acting as a mediator that prevents localized hot spots from developing into thermal runaway while preserving the high-temperature superconducting performance
2Stress or pressure
If REBCO tapes are used to operate at higher magnetic fields, then the magnetic field capability is improved, but the Normal Zone Propagation velocity becomes significantly lower leading to slow-spreading normal zones and potential thermal runaway
Solution Approach 1:
The tape structure is divided into multiple superconductor layers with conductive buffer layers in between. This segmentation enables the normal zone to propagate across layers through the conductive buffers, increasing NZP velocity and preventing thermal runaway while maintaining high magnetic field capability
Solution Approach 2:
The patent creates a composite tape structure combining superconductor layers with conductive buffer layers. This composite design leverages the high magnetic field capability of REBCO while the conductive buffers provide enhanced heat and current distribution to prevent thermal runaway
3Ease of manufacture
If conventional REBCO tape designs are used, then manufacturing simplicity is maintained, but defects and hot spots occur leading to non-uniform critical current and reduced reliability
Solution Approach 1:
The tape is segmented into multiple parallel superconductor layers separated by conductive buffer layers. This segmentation provides redundant current paths, so if a defect occurs in one layer, current can redistribute through other layers and the conductive buffers, maintaining reliability while using conventional manufacturing techniques for each layer
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
These enhancements allow for better current sharing and reduced risk of thermal runaway, enabling REBCO tapes to maintain uniform critical current and withstand local defects effectively.
Implementation Method 1
conductive substrates, slotted superconductor films, and conductive buffer layers, along with thicker stabilizer layers and conductive materials to enhance current flow
Implementation Method 2
A High Temperature Superconductor (HTS) material, such as Rare Earth-Barium-Copper-Oxide (REBCO), can operate at relatively higher temperatures (at 77 K), at higher magnetic fields, or both higher temperatures and higher magnetic fields
Data Source
AI summary
A superconductor tape stack can have good current sharing characteristics and low contact resistivity. An electrically conductive material can be used to couple superconductor tapes to each other. In an embodiment, the superconductor tape stack can include double-sided superconductor tapes in a 2X configuration. In other embodiments, the superconductor tape stack can include single-sided superconductor tapes in a F2B configuration. One or more enhancements may be used to help reduce the contact resistivity. The enhancements can include slotted tapes, a conductive buffer layer stack, a relatively low resistivity substrate, a thinner substrate, a thicker stabilizer layer along sidewalls of the tapes, and combinations thereof. A superconductor tape may also have one or more of the enhancements described with respect to the superconductor tape stack. A magnetic coil can have a winding that includes the superconductor tape stack or the superconductor tape.