Hacker News Reader

Comment by ianburrell | Hacker News Reader

REBCO high-temperature superconductors have potentially changed the game. They can support stronger fields which means smaller devices for same confinement. Commercial production seems to only started in the last decade.

MIT's research, spun out as CFS, may be prompting other startups.

View on HN

Is there any fundamental limit we’re hitting on magnetic fields or might we see another 10-100x increase in field strength in the future?

Nobody knows, is the short and boring answer. We don't have a sufficiently detailed understanding of what drives critical field strength in these materials (otherwise we'd have room temperature superconductors or have ruled out their existence already).

It would be shocking if HTS manufacturing research did anything other than accelerate. If there are fundamental physical limits to run in to then they are very far away. This is deep in the engineering limited area. How much abuse from strain and radiation can your HTS handle? The better your answer at a cheaper cost, the smaller and more powerful of a machine you enable. Humans know how to make pretty strong steel, so the superstructure won't be a limiting factor for a while if ever. Making HTS tapes and divertors that can handle what we ask of them are the material challenges. There is room to be clever with physics to lessen the divertor problem.

Actually, I think the strength of modern steels is a limiting factor for fusion magnets. Plasma "beta"s are only a few %, so for a few atmospheres of plasma pressure your magnetic cage needs to be like a pressure vessel that contains hundreds of atmospheres. And with large holes poked through it for access. If you look at CFS's magnet test from last summer, there's a huge amount of steel.

60% of the mass of the ARC reactor is the steel support structure to resist JxB forces. A magnetic field 10-100x higher would exert such strong forces (magnetic pressure scales as B^2) that no material could resist them. So: strength of materials.

Reply on news.ycombinator.com