The next generation of magnets have the potential to change the world and is being worked on by Yavuz Oz, a researcher at the National High Magnetic Field Laboratory. The HTS wires that power these superstars are magic. Credit: Florida State University.
The next generation of magnets has the potential to change fields such as energy storage and medicine. The HTS wires that power these tools are magic.
A team from the College of Engineering at Florida A&M University has discovered how to improve the performance of a type of HTS wire. Their work was published.
"There are three types of HTS wires that can be used to power magnets," said Yavuz Oz, a researcher at the National High Magnetic Field Laboratory. Two of these are made in rectangular form, and look like rolls of tape when wound up, and the third is round. We found that the round one is better for magnets, and we want to find ways to make it even better.
Oz is working with a team of researchers at the college, led by David Larbalestier, chief materials scientist at the National High Magnetic Field Laboratory and Marie Krafft Professor of Mechanical Engineering at the FAMU-FSU College of Engineering.
The team is looking at the structure of Bi2Sr2Ca1Cu2Ox.
The way Bi-2212 wires are processed results in a structure that is naturally connected. This allows us to focus on the beneficial aspects of the structure that we can change in production to improve performance.
Current travels through the strongest magnets and they have kilometers of wire to power them. Some superconductors have bad connections in the wire. These regions are costly and time consuming. They are problematic in rectangular wires.
Bi-2212 round wires are free of disconnected regions. Bi-2212 round wires are made by melting Bi-2212 powder. The Bi-2212 powder has well-textured grain colonies when cooled slowly. The wire can achieve high critical current densities. Current can flow across the grain boundaries in the underlying structure and this improves critical current capacity.
The Brick-Wall model is the first experimental evidence for a theoretical model of current flow in Bi-2212 wires. "It claims that electrical current prefers certain types of connections with large surface area."
The Bi-2212 round wires have a structure made of crystal grains that rotates slowly along the wire, giving it the same superconducting properties in all directions. Other wires made in tape form have a uniform alignment of crystal grains. It is more difficult to design magnet coils when the tape develops different properties when measured in different directions because of the way the grains align.
The scientists used a technique called "over-doping" to experiment with Bi-2212 wires. The technique increases the critical current density and magnetic field to make the material perform better.
"Superconductors can only carry electrical current with perfect efficiency if there is no heat inside the material," Oz said. The superconductor is made of a magnetic field. When the material carries electrical current, the heat generated by the vortices can cause performance problems. By introducing the right kinds of impurities, we can 'pin' these vortices and prevent them from moving.
It's necessary for high, critical-current density and better performance to have strong vortex pinning. The inherently well- connected nature of Bi-2212 does not change when over-doping is reversed. The researchers were able to narrow down the search for what makes Bi-2212 perform so well with the help of this finding.
Oz said they hope to push Bi-2212 to full potential to become the prime high-temperature superconducting material of choice.
Bi-2212 round wires may provide the necessary technology for an upgrade to the Large Hadron Collider at the European Organization for Nuclear Research, the world's highest-energy particle collider.
The Conundrum of strongly coupled supercurrent flow in Bi-2212 round wires was reported by Yavuz Oz and his colleagues. There's a DOI for "PhysRev Materials."
The performance of high-temperature superconductor was probed on December 16th, 2021.
The document is copyrighted. Any fair dealing for the purpose of private study or research cannot be reproduced without written permission. The content is not intended to be used for anything other than information purposes.
