[pauljurczak]

20 K is high temperature? Well, I better take my mittens and ushanka off. I thought 77 K was the official threshold: https://en.wikipedia.org/wiki/High-temperature_superconducti....

[willis936]

You'd never operate a superconducting magnet at its crtical temperature.

Check out figure 5 here. The relevant bit is the vertical slice along the left edge. Crtical current density and internal magnetic field both go way up when you go below LN2 temps. You could make an LN2 HTS magnet, it just wouldn't be in the 1T+ class.

https://cds.cern.ch/record/2277484/files/Bruker%20HTS%20Fit....