New records on Wendelstein 7-X

Does it kill the idea of a tokamak as an energy production device? As in a stellarator proving the much more promising design...

Not an expert on the topic by any means, but IIRC:

- Those designs have been in parallel R&D for decades

- Tokamaks are conceptually simpler, thus might be easier/faster/cheaper to make into viable installations

- Stellarators are WAAAAAY more complex to design and build but AFAIU they would have the huge benefit of being able to sustain the plasma for way longer for the same "startup cost" of a cycle since the particles of the plasma are routed somewhat like they're on a mobius strip instead of a simple torus (which should make it easier to confine more particles for a longer time).

I recall having read (several years ago) that the simulation technology of the 90's wasn't really up to the task of aiding in the design of those weird wavy magnets for Wendelstein 7-X, an unfortunate reality which delayed the project a lot.

I'm no expert, but from the full press release it appears this experiment is the first time they've even been competitive with tokamaks, and are still behind the latest (unpublished) tokamak results.

It'll be a question of manufacturing. A tokamak is a fairly simple torus, with at least some similar parts. Stellerators are freakishly complicated 3D structures that require submillimeter precision.

So it might end up being cheaper to construct a larger tokamak.

Perhaps, unless you fall prey to the sunk cost fallacy and have already spent a bazillion dollars on generations of tokamaks!

Both ideas are pretty old (50s) and in development for a long time. Both designs have their pros and cons. The biggest drawback of the Tokamak however is that it can only be pulsed... which is kind of dumb to actually generate and provide energy in the long run. You really want the Stellarator here, since there it is at least theoretically possible to run "for ever" (not entirely true, but long enough cycles to be used in a power plant).

There are 2 podcast episodes with the guys who run Wendelstein here: http://www.alternativlos.org/51/ (it's German tho)

Tokamaks are conceptually elegant but contain significant inefficiencies which negatively impact potential net power output. Both tokamaks and optimized stellarators have magnetic fields possessing omnigeneity [1], but tokamaks require two magnetic fields (poloidal and toroidal) whereas stellarators employ one.

The bigger question is if magnetic confinement fusion will lead to the best energy producing devices. Competitors include inertial confinement, pinches, or some other exotic method. If a magnetic confinement fusion device produces net power, it's going to be a stellarator.

Sources:

[1] https://en.wikipedia.org/wiki/Omnigeneity

Maybe, maybe not. There are dozens of unsolved problems to get to commercial fusion. For a lot of the problems, to solve them it doesn't matter if it's a stellarator or tokamak.

I would also be super careful about celebrating new designs as the way forward that will replace everything. When you look at the history of combustion engines we had a ton of new approaches (for example rotary engines) but after looking at all factors it turned that evolutionary changes to existing designs was the way forward.

These podcasts are really good. I remember the part where they had problems with some screws and the simple solution was to coat them with diamond.