US creates world record-breaking highest-performance superconducting wire

A research team led by Amit Goyal, a distinguished professor at the US Department of Chemical and Biological Engineering at the University at Buffalo, has developed the world’s highest-performance high-temperature superconducting (HTS) wire.

The wire operates at temperatures of -451 to -321 degrees Fahrenheit (-268 to -196 degrees Celsius), which is still extremely cold but higher than the absolute zero temperatures that other superconducting materials work at.

HTS wires could be a critical component of our energy future since the technology can facilitate electricity transmission at zero resistance. However, their applications range beyond loss-less power transmission to doubling power output from offshore wind farms, building superconducting magnetic energy storage systems, and other energy infrastructure.

In recent times, HTS wires have also found applications in nuclear fusion reactors and next-generation imaging and spectroscopy techniques. While HTS wires offer the advantage of relatively warmer operating temperatures, they are still expensive to make.

This is where researchers at the University of Buffalo (UB) have made a major advance.

How was the HTS wire made?

Worldwide, companies engaged in HTS wire manufacturing either use biaxially textured substrates (RABiTS) technology, LMOe-enabled ion-beam assisted deposition (IBAD) MgO technology, or nanocolumnar defects at nanoscale spacings technology. Interestingly, all these technologies have been developed by UB researchers under Goyal’s leadership.

In their recent approach, the researchers combined IBAD technology with nanocolumnar defects technology. The latter method uses simultaneous phase separation and strain-driven self-assembly, which allows insulating or superconducting materials to be incorporated into the superconductor . Nanoscaled defects introduced in this manner create superconducting vortices that allow higher supercurrents to flow.

The researchers used an advanced pulsed laser deposition system to make an HTS film on a rare-earth barium copper oxide (REBCO) wire.

“We also conducted atomic-resolution microscopy using the most advanced microscopes at the Canadian Center for Electron Microscopy at McMaster University for characterization of nanocolumnar and atomic-scale defects and also conducted some superconducting property measurements at the Università di Salerno in Italy,” added Goyal in a press release.

Performance of the HTS wire

With their recent innovation, the researchers attained the highest critical current density and pinning force for all magnetic fields and temperatures from 5 kelvin to 77 kelvin (-451 to -321 degrees Fahrenheit).

At 4.2 kelvin, the wire demonstrated carriage of 190 million amps per square centimeter without any external magnetic field, also known as self-field. With a magnetic field of 7 tesla, the current carriage was 90 million amps per square centimeter.

As the temperature was increased to 20 kelvin, the temperature at commercial fusion reactions, the wires carried 150 million amps per square centimeter self-field and over 60 million amps per square centimeter at 7 tesla.

The noteworthy feature of this achievement is the thickness of the HTS film, which was only 0.2 microns thick but carried currents that are typically achieved with an HTS wire ten times thicker.

With regards to pinning force, the wire could hold down forces as high as 6.4 teranewtons per cubic meter at 4.2 kelvin and about 4.2 teranewton per cubic meter at 20 kelvins when the external magnetic field was 7 tesla.

“These results will help guide industry toward further optimizing their deposition and fabrication conditions to significantly improve the price-performance metric in commercial coated conductors,” added Goyal in the press release. “Making the price-performance metric more favorable is needed to fully realize the numerous large-scale, envisioned applications of superconductors .”

The research findings were published in Nature Communications today.