[dukwon]

"at least several weeks" is technically correct but I think a bit of an understatement. A sector takes about 3-4 weeks to warm up and 4-5 weeks to cool down. Then it needs to undergo powering tests and probably some "training" quenches.

Since the winter shutdown is scheduled for end of October (thanks to the energy crisis), there's a good chance we are finished with proton collisions for the year. If the leak can get fixed and the sector cooled down by mid/late September, we might have time for the heavy ion run. Last year's ion run was cancelled due to shortening the year, so 2 years in a row would not be great.

[foobarian]

Is there any plan to migrate to higher temperature superconductors which might not require such low temperatures?

[sbierwagen]

The Future Circular Collider is looking to switch to niobium-tin from LHC's niobium titanium. https://en.wikipedia.org/wiki/Future_Circular_Collider Unfortunately they'll still run at liquid helium temperatures-- while advanced superconductors have higher critical temperatures, the critical field (magnet strength) still goes higher as the magnet gets colder, and that's the figure of merit for collider designers. http://hyperphysics.phy-astr.gsu.edu/hbase/Solids/scbc.html

This is why you see new fusion reactor designs like the SPARC which use HTS superconductors throughout still use mildly exotic cryocoolants like liquid hydrogen-- not as expensive as liquid helium, but still better performing than liquid nitrogen. (Not to mention that liquid nitrogen is annoying in nuclear applications: it's easily activated by neutron radiation and deposits monoatomic carbon dust through your cryocooler circuit)

[scarmig]

They introduce their own problems. They're typically brittle ceramics, making them hard to work with. They're more expensive to manufacture. And they have a lower critical current density (i.e. there's less current they can carry before losing superconductivity).