
Successful second round of fusion experiments with Wendelstein 7-X - mrfusion
https://www.ipp.mpg.de/4550215/11_18
======
ttul
Experiments like Wendelstein remind me that the only thing holding back fusion
power is money for research like this. Every year, we spend billions on fossil
fuel exploration because the return on investment is quick - just think about
all the wells going in to extract shale oil.

What if we collectively had the will to invest this much into fusion?

~~~
hyperbovine
Err no, money is not "the only thing" keeping us from having fusion power. I
can think of one other thing which is that it's damn hard to create stellar-
core conditions inside of a small containment vessel on Earth. It's not
obvious that throwing more money at the problem is going to change this. After
all, fusion research has been funded in some form or another since the 1950s.
I'll bet if you added up all the research dollars that have been expended on
fusion, it would come to quite a tidy sum indeed. Despite this, we still have
little to show for it.

~~~
cygx
Just for the record, you don't re-create stellar-core conditions with earth-
bound fusion devices: We don't have the means, and the yield would suck.

Now, it is true that there's still fundamental research to be done until
energy production via nuclear fusion becomes a reality, but we're reasonably
confident that we could make the conventional approaches work.

However, that research is Big Science, and there's no political will to fund
it properly (the graph that people like to cite is
[https://commons.wikimedia.org/wiki/File:U.S._historical_fusi...](https://commons.wikimedia.org/wiki/File:U.S._historical_fusion_budget_vs._1976_ERDA_plan.png)
). ITER suffered from this as well, and W7-X basically only exists because
German reunification happened, and the German government was looking for a big
science project - _any_ project - they could leverage to funnel money into
East Germany. The plans for W7-X just happened to be ready at the right time.

~~~
sandworm101
>>> However, that research is Big Science,

Not all of it. The big science approach is a function of "pure" fusion
research done from the assumption that containment/ignition only comes from
magnetic fields and particle collisions. Some are approaching it from
different directions, even using physical forces to trigger ignition (ie
slamming the hydrogen with a big hammer). This isn't crazy stuff, just a more
practical approach from people who see the problems from a different
perspective.

[https://en.wikipedia.org/wiki/General_Fusion](https://en.wikipedia.org/wiki/General_Fusion)

[https://www.canadianbusiness.com/technology-news/crazy-
geniu...](https://www.canadianbusiness.com/technology-news/crazy-genius/)

"At the centre will be a sphere, three metres in diameter, inside which molten
lead swirls at high speed creating a vacuum, or vortex, in the middle. Arrayed
around it will be 200 to 300 pistons, each the size of a cannon. Firing in
perfect harmony, they will create an acoustic wave that collapses the vortex
at the very moment a plasma injector shoots hydrogen isotopes, the nuclear
fuel, into it. If General Fusion has its physics right, the heat and pressure
will ignite a fusion reaction that spins off countless neutrons which will
heat the lead even more. Pumped through a heat exchanger, that hot lead will
help generate steam just like a conventional thermal power plant."

~~~
cygx
Hence my qualifier 'conventional approaches'. I wish those working on
alternative approaches the best of luck, and some of the experiments look like
a lot of fun (they get to blow things up - I've seen videos where plastering
was raining from the ceiling of the control room ;)).

~~~
sandworm101
I'd say that the "conventional" approach for triggering fusion is physical.
We've been triggering fusion in nuclear weapons for many years and the
physicalities of it are very well understood. What general fusion is doing is
essentially a non-destructive nuclear secondary. Triggering fusion with
magnets, without moving parts, is imho the unconventional way of getting to
fusion. It is only conventional in comparison to fusion research. The
practical users of fusion (the armed forces) don't use magnets.

------
tlb
If this ends up being the right design for fusion, it may be the most weirdly
shaped human artifact, where the shape is fundamental to its operation and not
decorative. It's far more complex than a mere turbine blade or venturi. Or can
anyone suggest a weirder one? (Define weirdness as the Kolmogorov complexity
of the shape, within the precision needed to work properly.)

~~~
pjungwir
The weird design makes me as a layman skeptical of the tech's potential, but
I'd love to hear why I'm wrong:

\- The randomness and lack of symmetry suggest that we are lacking insight
into the problem, like an inelegant physics explanation or an over-fitted
model. It's not just that it's complex, but it doesn't even seem to have
"parts" that work together. Conceptually fusion seems pretty simple: why in
principle does harnessing it require super-human complexity?

\- If such extreme contortions and micro-optimizations are required to get
this far, how much potential can there still be on this path? In software, if
you are replacing divisions with bit shifts, maybe you really need a different
algorithm. I understand this is just a research project, but if everything is
so finely tuned already, how do you make improvements?

I don't know anything about fusion power, but those are the intuitions I feel
when I see the plasma vessel photo and read how it was designed.

~~~
thanksDr
It's extremely symmetrical!

~~~
cygx
It's all about the magnetic surfaces. Some pictures:

[https://images.slideplayer.com/33/10482660/slides/slide_9.jp...](https://images.slideplayer.com/33/10482660/slides/slide_9.jpg)

[https://www.nature.com/articles/ncomms13493/figures/1](https://www.nature.com/articles/ncomms13493/figures/1)

[https://imgur.com/gallery/eikBLMX](https://imgur.com/gallery/eikBLMX)

------
nine_k
With fusion devices having trouble to confine the plasma for long times, I
wonder if a massively-parallel fusion plant woud be feasible.

Let's assume that plasma destabilisation does not damage the device, and is a
mundane event.

Build 10 or even 20 fusion devices (economy of scale!) feeding the common heat
buffer, e.g. a large reservoir of a molten salt or metal. Feed conventional
turbines off the heat of the heat tank. The tank evens out the input power
jumps.

Now we can restart the fusion in every fusion device every so often, provided
that restarting it is made a mundane operation, too. It, of course, takes a
lot of electricity to pump into the magnets. Conveniently, we have a mighty
power plant right here. Dumping the magnetic/electric energy from the magnets
requires a huge sink. Luckily, we already have such a sink co-located.

Building the plant takes a massive investment. Luckily, the architecture
allows to build it piecemeal, feeding the next added unit with the power of
the already built units.

BTW the waste heat could be directly reused in some kind of chemical
processing, like smelting, or maybe even synthesis of carbohydrate fuels from
ambient carbon dioxide and water.

~~~
antocv
What is it with physicists and molten salt?

Every battery-tech, pro-nuclear, fusion related news have to have somebody
chiming in "molten salt".

Just an observation.

~~~
08-15
Molten salts are hot!

SCNR. Seriously though, molten salts are great heat transfer media, a bit like
water, just at higher temperature and still low pressure. They are also
completely immune to radiation damage, which is a big deal if you have 14MeV
neutrons flying around and something _has_ to stop them. Chemistry in molten
salts is also interesting. Things can be extracted (say, into a molten metal
phase) or precipitated, and some reactions just happen at 600 degrees while
they need platinum and palladium catalysts at room temperature. What's not to
love?

~~~
antocv
Can you teach me more about the radiation properties of molten salts? Didnt
know molten salt is immune to radiation, why would that be? Thats cool,
though.

~~~
pfdietz
Because they (or, at least, the ones being discussed) have no covalent
chemical bonds or other static arrangements of atoms that can be disrupted.
The ions are all just single atoms with more or fewer electrons than the
neutral versions of those elements. The atoms can be ionized by radiation, but
the resulting weird oxidation states just fall back to chemical equilibrium as
the electrons redistribute.

------
ChuckMcM
I love these guys, steadily working through the issues, making steady
progress. I think with a slightly different diverter design they could claim
to have the worlds first plasma cannon :-).

Pretty insanely complex machine, and really awesome results. Congrats!

~~~
tetha
This is what I find impressive as well.

They have this absurd shape, because the algorithm says it works, and they say
it contains plasma. It does.

They say they will test this to hold 10 - 12 seconds of plasma. It does.

They say they will work on this and expand this to hold 30 seconds of plasma.
It does.

This just feels like really solid engineering or practical science. Those 30
minutes will happen without much delay.

------
saganus
Does anyone have any idea how do they take pictures of the plasma?

That seems quite hard considering the temperatures and the strong magnetic
field.

~~~
sballin
I operate a fast camera at W7-X. It's a normal high-speed camera that records
light in the humanly visible range, and the plasma emits in that range and
reflects off the walls. IR cameras are most often used to gauge the
temperatures of vessel wall components.

Our camera looks through a pinhole in the vessel wall, but it sits a few
meters away from the machine and gets that view through a bundle of optical
fibers. There wouldn't be enough space to place the camera right at the
pinhole because of the magnets and their cooling systems, and the magnetic
fields would be pretty high. The camera needs to be shielded from the fields
for its electronics to work properly, and the shielding box perturbs the
magnets' field, so moving the camera far away is a good idea. We don't worry
about neutrons, because W7-X plasmas are fueled with stable helium and
hydrogen (no deuterium or tritium so far, mainly due to onerous nuclear
regulations in Germany), and these fuels don't produce many neutrons at all.

~~~
adrianratnapala
> Our camera looks through a pinhole in the vessel wall, but it sits a few
> meters away from the machine and gets that view through a bundle of optical
> fibers.

Wait, so does this mean that you have a _camera obsucra_ with an array of
optical fibres at its back, and then you have an ordinary CCD camera imaging
the other end of the fibre array?!?!

~~~
sballin
I guess the word pinhole is misleading here, I think it's a few cm in
diameter. Behind it there's an array of lenses that projects the view onto a
fiber bundle, then a lens at the other end of the bundle projects that view
out. That light goes through a beam splitter which shares it between our
camera and another one in the shielding box.

Most imaging in fusion is done like this because of space constraints,
magnetic fields, and neutron fluxes.

------
zeristor
I thought the main problem with nuclear fusion is neutron capture converting
the structural materials which are no longer fit for purpose.

I'm quite keen on aneutronic fusion, Boron 11 + a neutron, which converts to
three alpha particles which can lose their energy to magnetic fields
generating electricity, no need for any Victorian steam engines.

The huge downside is that works at much much higher temperatures, but if you
can't solve the neutron capture issue...

------
beambot
> The result was high plasma densities of up to 2 x 1020 particles per cubic
> meter – values that are sufficient for a future power station. At the same
> time, the ions and electrons of the hydrogen plasma reached an impressive
> temperature of 20 million degrees Celsius.

> Since the fusion fire only ignites at temperatures of over 100 million
> degrees, the fuel [...]

Would it be accurate to say that this gets us 20% of the way there, or is that
overly simplistic?

~~~
shaqbert
Unfortunately overly simplistic. The challenge with higher plasma temperatures
is that the internal shielding needs to be better than the current graphite
tiles. They will upgrade those next and go with more complicated water cooled
carbon fiber strengthened carbon tiles.

Note that Wendelstein 7x will never operate to produce actual fission with DT
fuel, because that is (a) outside its mission goal, which is to research
plasma behaviour at conditions close to what is needed in a power plant and
(b) dealing with the neutron bombarding creates all sorts of complexities in
terms of the blanket. Not really solved here as well, as Wendelstein 7x is a
nightmare to disassemble and upgrade. For a power plant maintenance and
serviceability needs to be build into the design. And (c) they don't have the
government permission to deal with nuclear material and nuclear waste.

So no, we are not 20% there. But we have proven that (a) the Stellarator
actually has wings, and (b) plasma physics so far behaves mostly as predicted.
Especially the latter is something to be celebrated, because plasma is nasty
in terms of physical properties, really complex to model, etc.

------
nefitty
I found this panorama shot on their home page:
[https://www2.ipp.mpg.de/ippcms/eng/externe_daten_en/panorama...](https://www2.ipp.mpg.de/ippcms/eng/externe_daten_en/panoramaw7x/)

------
torgian
In the words of peter griffin, why aren’t we funding this more?

------
emilfihlman
The name is really scifi.

I love it!

------
samirm
Awesome progress, but I feel like the stellerator design won't be
scalable/feasible :/

------
chiefalchemist
"Although Wendelstein 7-X is not designed to generate energy, the device is
intended to prove that stellarators are suitable for use in power stations.
With Wendelstein 7-X the intention is to achieve for the first time in a
stellarator the quality of confinement afforded by competing devices of the
tokamak type."

This was at the very end.

While competition is certainly a positive, this doesn't sound like they're
interested. Therefore, given the importance of fusion (read: there's a massive
immediate need on the order of saving the planet), shouldn't the time and
effort being put into stellarators be devoted to something that's important in
the immediate?

~~~
theresistor
I would say the opposite. Achieving fusion power is so critical to the long
term sustainability of human technological civilization that we cannot afford
to put all of our eggs in one basket, and hope that we picked the right one.

~~~
chiefalchemist
Fair enough. And I agree. However, to be clear, that's __not__what this
article says. Per the quote I pulled.

~~~
aqme28
I think you're misinterpreting the quote, and that's probably why you were
downvoted.

