The announcement today about one more step towards fusion power is great news.

While this is definitely progress, it is a running joke in the physics community that fusion power is always a decade or two into the future, and has been for about eight decades.

Still, progress is progress. So congrats to the teams involved!

I got to visit a fusion experiment back in 2014 at the Max Planck site in Greifswald, Germany. The photo is a part of the reactor behind some scaffolding.

#Fusion #Physics

Creating fusion power is really really hard to do. It is a massive effort just to have gotten to where the research is today. Keep in mind that this is a process that only naturally occurs inside the core of a star. It is an incredibly difficult environment to duplicate. #Fusion #Physics

@veronica The folks at CFS are confidently spinning up supply chain to crank out superconducting magnets for a fleet of magnetic-confinement fusion reactors (entirely different tech from NIF's inertial confinement).

They are still 2 years shy of having their prototype online and generating, but putting their money where their mouths are in terms of readiness for commercialization...

@elfprince13 There's been a lot of prototypes. Is this a design expected to generate sustained fusion? Or just a research reactor?

@veronica It's expected to be online in 2025 and generate sustained fusion, and they're actively working on siting grid access for the commercial scale version a few years down the line. If you haven't been following their work, I highly recommend checking it out.

@elfprince13 Thanks, will do. I'm mostly checking in on ITER and the stellarator at Max Planck from time to time.

@veronica CFS is an *incredibly* well-funded ($2B) spinout from the Alcator C-Mod team at MIT with productized 20T high-temperature superconducting magnets.

cfs.energy/technology/#sparc-f

@elfprince13 20T, that's impressive. I was a fellow on the HiLumi LHC project at CERN, and when I left they were still working on the 11.4T magnets needed. Granted, that was in 2019.

@veronica @elfprince13

I'm not really a magnet expert, however the geometry also matters in how easy it is to get a high field.

The LHC magnets are two-aperture bending magnets with a somewhat complicated winding and mechanics, and extremely tight tolerances for field quality at a wide range of currents, and not much room for adjustment once they are made.

@veronica @elfprince13

It could be that the high field magnets used in tokamaks (torroids, D-shaped solenoid that bites its own tail) are easier to get up high field?

@kyrsjo @veronica so this is related to one of the reasons I historically have favored stellarators - with a tokamak you're imposing an external magnetic field on the plasma (which really just wants to faff about and do its own thing).

@kyrsjo @veronica Moreover, the magnetic field is weaker on the outside of the torus due to relative increase in surface area with same number of coil windings, so as particles take random walks out through the field, you get one-sided error, and they begin to concentrate outward which is bad

@kyrsjo @veronica with a stellarator you physically bend the plasma into a shape that induces its own useful magnetic field, in such a way that you have a globally average good curvature minimizing the tendency to drift outward, but sadly the solutions to the differential equations letting you physically realize this really cool idea leads to shape require stupidly tight tolerances to manufacture and are thus much more expensive to build at any kind of scale.

@kyrsjo @veronica this had led to a bunch of political decisions wherein tokamaks get favored as the "easy" solution, and stellarators have a hard time getting funded despite being the "more correct" approach (PPPL literally has a stellarator in pieces in a garage because funding got cut before they were allowed to put them together)

@kyrsjo @veronica anyway, politics aside, the tokamak folks basically just need to make a "big enough" model so that the curvature isn't too crazy to get the confinement they want (ITER), or just build an insanely powerful magnet to do it at a reasonable scale (CFS).

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@kyrsjo @veronica there are some other variations playing with the curvature of the basic toroidal design within this overall space, but that's the basic gist of the MCF game*.

*if you really want to deep dive there are also Field-Reverse Configurations (FRCs), which have a few passionate devotees, but are even more stalled (public-) funding wise than stellarators.

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