Wendelstein 7-X sets new fusion record
26 comments
·June 3, 2025Robotbeat
IshKebab
So on this graph they're at about 0.2e20, but it also says they need 3e21 (and the graph on Wikipedia agrees)... So are they 150x off the target? 3e12 is a typo I guess?
willis936
Yeah it's 3E21 in SI units. The wikipedia graphs also highlight how nonlinear performance scales across machines. W7-X isn't 1000x larger than T3, yet performs ~1000x better. Confinement field strength (a little expensive) and major radius (very expensive) are knobs that turn these from research machines into power plants.
_Microft
Here's the statement on the official website if you prefer that:
ChuckMcM
I love these guys and gals. Just knocking down the engineering goals one after another. It's been a lot of fun watching their progress over the years. If they told me "we're going to build a energy producing stellarator in 5 years" I'd actually believe them. :-).
lukan
Give them the funding and they would love to start ..
But there is a german fusion startup about to build a stellarator.
https://www.proximafusion.com/about
(I assumed there was some sort of cooperation with Wendelstein, but found no mentioning of such on a quick look now)
s1artibartfast
Archive and alternate source:
https://phys.org/news/2025-06-wendelstein-nuclear-fusion.htm...
ipnon
I have a feeling ASI will follow similar trajectory as fusion, with the critical intelligence explosion always 2 years away. AGI by Turing’s definition is here. But fusion my whole life has been just around the corner…
ahoka
If we ever have access to unlimited cheap energy, then we are going to boil the world.
ninetyninenine
I have a question. How come the mathematical modeling and simulations haven't yet yielded us the perfect design that will get things right?
How come we have to build it and test it to know if it works?
Do we lack a mathematical model?
regularfry
Same question got asked of Bob Bussard when he visited Google to talk about his whiffle-ball design. It's not that we lack models, it's that they're effectively incomputable at the scale we'd need them to be.
In a fluid, effects are local: a particle can only directly effect what it is in direct contact with.
In a plasma, every particle interacts with every other. One definition of a plasma is that the motion is dominated by electromagnetic effects rather than thermodynamic: by definition, if you have a plasma, the range of interactions isn't bounded by proximity.
This doesn't apply quite so much to (e.g.) laser ignition plasmas, partly because they're comparatively tiny, and partly because the timescales you're interested in are very short. So they do get simulated.
But bulk simulations the size of a practical reactor are simply impractical.
burnt-resistor
Putting a bunch of much more viscous radioactive material within proximity of each other is simpler than squishing and maintaining confinement of plasma under extreme conditions.
Fission reactors are relatively "easier" to simulate as giant finite element analysis Monte Carlo simulations with roughly voxels of space, i.e., thermal conductivity, heat capacity, etc. I happened to have been involved with one that was 50+ years old that worked just fine because of all of physicists and engineers who carefully crafted model data and code to reflect what would be likely to happen in reality when testing new, conventional reactor designs.
The problems with fusion are many orders-of-magnitude more involved and complex with wear, losses, and "fickleness" compared to fission.
Thus, experimental physics meeting engineering and manufacturing in new domains is expensive and hard work.
Maybe in 200 years there will be a open source, 3D-printable fusion reactor. :D
KingOfCoders
The difficulty is in the details. Small differences lead to bigger differences, like in chaos theory [0] What if the model says this coil needs to be 23.1212722 centimeter? Or two coils need to be 37.1441129 centimeters apart? How do you build that? Mathematics is always much more precise than engineering.
[0] https://en.wikipedia.org/wiki/Edward_Norton_Lorenz#Chaos_the...
HPsquared
You need to think of what happens if it's 0.001 cm too big, small, etc. Manufacturing always involves errors and engineering requires tolerances.
padjo
We still have wind tunnels and aerodynamics is a pretty simple problem compared to fusion.
jablongo
It seems like the ranking of likely success in the next 10 years is
1. Commonwealth (tokamak w/ high temp superconducting magnets)
2. Helion (field reversed configuration, magnetic-inertial, pulsed) ....
?. Wendelstein (stellarator)
Maybe stellarators will be the common design in 2060 once fabrication tech has improved, but for the near future I think its going to be one of the first two.
dralley
It'll be really funny if we get a commercial fusion device before ITER has even been turned on.
I'm sure they developed some really useful technology in the process of building the thing, but I suspect they would have made more progress faster if they had taken a more iterative approach.
prpl
this discounts the likelihood that other breakthroughs are correlated with ITER in some way.
The first transistor in Silicon Valley wasn’t made by Shockley.
fpoling
I doubt Helion will work. By their own paper using simplified model their device allows theoretically for Q no more than 2 (2 times energy produced versus energy spent). They claim with their like 90% efficient capture they still get net energy gain. But typically reality way messier than model and I will be surprised if they archive Q=1.
Tokamaks main problem is plasma instabilities. While Commonwealth may archive high Q briefly, nobody knows how plasma will behave at those conditions and long operations may not be possible.
Stellarators on the other hand do not have plasma stability problems. So my bet is on those.
audunw
If the goal is viable commercial operation, Helion has vast benefits over the other approaches when it comes to the economics of turning the fusion energy into electricity.
All approaches have huge hurdles to overcome. Helion may have bigger challenges on the Q side, but all-in-all I think the probabilities of being viable ends up similar.
All other fusion power plants are thermal power plants. I suspect all thermal power plants will end up being economically unviable in the world of renewables, for various reasons. They’re just too bulky and slow, and require special consideration wrt cooling. It’s one of the reasons why gas power is king these days.
If we think really far ahead, the scaling of thermal power plants is limited by the heat they put out. It ends up contributing to global warming just from the thermal forcing they apply to the environment. The effect of the ones we have today are already surprisingly significant. Helion is a path to being able to produce a huge amount of energy with fairly limited impact on the environment (eventually limited by the thermal energy they dump, but perhaps they can use thermal radiation panels that dump the waste heat energy directly to space)
niemandhier
Proxima Fusion builds a stellator. As far as I remember they were founded by wendelsteinians.
They are the only fusion startup I know of that was faster than their own timeline in the last year.
drewvolpe
4. Acceleron (muon catalyzed)
There's huge advantages to muon catalyzed if they can get it to work. Plants would be orders of magnitude smaller and cheaper to build.
GloamingNiblets
Good list, I'm also keeping an eye on Tri Alpha Energy and First Light Fusion. TAE recently announced [1] initiating a field reversed configuration with no plasma injectors, only neutral beam injection, which is a pretty big deal in simplifying the design.
[1] https://tae.com/tae-technologies-delivers-fusion-breakthroug...
actinium226
Thea Energy is working on a stellarator that doesn't require the complex shaping coils that W-7X is using. I'd put them above Helion and below CFS, but in a couple years they might take the top spot.
Since the article opening sentence and headline don’t say it: The breakthrough is the plasma “triple product,” literally just the plasma temperature (in keV) times particle density times (confinement) time. The Lawson Criterion. https://en.wikipedia.org/wiki/Lawson_criterion
A useful fusion power plant needs a triple product of at least about 3e12 keV * s * m^-3.
They weren’t fusing things (at least, not much). This is a figure of merit that allows you to compare, across all the different fusion methods, how well you would be able to fuse the plasma if you were using burnable fuel such as deuterium and tritium (isotopes of hydrogen that have one or two extra neutrons).