The big thing about this is that it's achieved using so-called High-Temperature Superconductor material, where the superconducting transition temperature is bas

The big thing about this is that it's achieved using so-called High-Temperature Superconductor material, where the superconducting transition temperature is basically anything higher than the < 10ish K that conventional superconductors require. HTS such as YBCO have several attractive properties besides their less-cryogenic operating temperature such as higher max current per area (the 'critical current density'). But since HTS are generally ceramic in nature, they can't be straightforwardly worked and extruded to form wire in the way that 'conventional' metallic superconductors like NbTi can. So what they're proposing is to make relatively small sections of cable which can be made by simple stacks of conductor. Then they'll join them together in the final assembly by soldering. This of course is much easier than trying to wind one massive coil in one go, but now you have a plethora of conventionally-conducting joints between sections, which will heat up under operation. They argue that removing some additional heat at the HTS operating temperature of 20 K is preferable to having to cool to 4 K for conventional superconductors, which sounds reasonable. However I feel that this is tough to support on the mechanical front. Energized magnets want to move, and you can't let them move because that leads to heat production, which leads to quenching. You need structure to keep them from moving. So in addition to the electrical connections, you need lots of structural steel and welds. You've got a bunch of stuff in there with different expansion coefficients, so making it work out in practice should be challenging. The LHC program was set back over a year due to overheating in one bad magnet splice.