Talk-Polywell.org

Nik wrote:Providing that phase can be produced in bulk...

Providing the 'magnetic tolerance' doesn't limit it to very modest currents...

Provided quenches don't cause 'prompt disassembly'.....

Hey ! A resin-sealed puck of this stuff could easily be chilled in household freezer, stay superconducting for half an hour or more without further cooling...

D Tibbets wrote:but have any high temperature (liquid nitrogen temperatures) superconductors reached practical applications?

Now, LS Cable, a South Korean company based in Anyang-si near Seoul, has ordered three million metres of superconducting wire from US firm American Superconductor in Devens, Massachusetts.


American Superconductor have not disclosed the value of the deal. But Jason Fredette, managing director of corporate communications at the company, says that LS Cable will use the wire to make about 20 circuit kilometres of cable as part of a programme to modernize the South Korean electricity network starting in the capital, Seoul.


The superconducting wire is made using the ceramic compound yttrium barium copper oxide (YBCO), part of a family of 'high-temperature' superconducting ceramics that were first discovered in 1986. It remains a superconductor up to 93 kelvin (–180 ºC), meaning it can be cooled using liquid nitrogen.


This is in contrast to low temperature superconductors, which are made of metal and must be cooled to below about 30 kelvin (–243 ºC) with liquid helium. That makes them too expensive to be used in large-scale commercial applications.


Superconductors also lose their remarkable properties when current above a critical value is passed through them, so the search for a commercially viable superconductor has focused on materials that operate at a high temperature relative to low temperature superconductors and can carry large currents. At the moment, YBCO is the most promising material available.


Evolution not revolution


David Cardwell, professor of superconducting engineering at the University of Cambridge, UK, says it has taken nearly 25 years for YBCOto be commercialized because a brittle ceramic "is exactly what you don't want for making wires".