[HN Gopher] New records on Wendelstein 7-X
___________________________________________________________________
New records on Wendelstein 7-X
Author : greesil
Score : 176 points
Date : 2025-07-21 15:18 UTC (7 hours ago)
(HTM) web link (www.iter.org)
(TXT) w3m dump (www.iter.org)
| apples_oranges wrote:
| Looking at the picture, I wonder if complexity of these devices
| will significantly be reduced once it finally works. I assume a
| lot of the bells and whistles are needed to find the way, but
| once it's found..
| StevenWaterman wrote:
| Your question reminds me of the image showing how SpaceX raptor
| motors evolved https://imgur.com/a/4w3q3lS
| ortusdux wrote:
| I'm not keen on the idea of applying a 'keep subtracting
| things until it blows up' mentality to fusion reactors.
| bhaak wrote:
| The nice thing about fusion reactors is that they don't
| blow up but just don't work anymore.
| soperj wrote:
| they have fission reactors that have done that since the
| 60s (CANDU Reactor). They just don't help you produce
| nuclear bombs...
| philipkglass wrote:
| CANDU has low intrinsic nuclear proliferation resistance.
| It can run on natural uranium, so it's easier to fuel
| than light water reactors which need enriched uranium,
| and its online fuel-swapping design means that it's easy
| to switch to low-burnup operation for generating weapons
| grade plutonium. Current CANDU power reactors have
| extensive monitoring to confirm that they are used
| peacefully, but if e.g. South Korea had a security crisis
| and decided to pursue a crash nuclear weapons program,
| world opinion be damned, its CANDU based reactors at
| Wolseong could be quickly reconfigured for weapons
| purposes:
|
| https://en.wikipedia.org/wiki/Wolseong_Nuclear_Power_Plan
| t
| perihelions wrote:
| It's topical that India's nuclear weapons program was
| started up with a Canadian-supplied heavy water reactor
| (though not CANDU; a not-power-generating type).
|
| https://en.wikipedia.org/wiki/CIRUS_reactor
|
| > _" Canada stipulated, and the U.S. supply contract for
| the heavy water explicitly specified, that it only be
| used for peaceful purposes. Nonetheless, CIRUS produced
| some of India's initial weapons-grade plutonium
| stockpile,[6] as well as the plutonium for India's 1974
| Pokhran-I (Codename Smiling Buddha) nuclear test, the
| country's first nuclear test.[7]"_
| xorxornop wrote:
| I wouldn't be concerned about this, personally, for the
| precise reason that it is a _fusion_ device - not fission!
|
| Fusion is incredibly difficult just to start, let alone
| keep burning - unlike fission, which is only too happy to
| enter runaway conditions if not very carefully regulated.
| Fusion is like a little ember in your fireplace you have to
| carefully blow on to keep alight; fission is like keeping a
| fireplace lit by pouring gasoline into it.
| grues-dinner wrote:
| I'd say (older-generation) fission is more like having an
| indoor swimming pool filled with burning gasoline, but
| keeping the windows shut so there's only enough air for
| it to burn at the rate you want to heat the house.
| HPsquared wrote:
| Or a swimming pool full of those spicy rocket propellents
| discussed in the book _Ignition!_ which have combustion
| products like hydrogen fluoride.
| exe34 wrote:
| "Things I will not work with" - "at this point hydrogen
| fluoride loses its gentle nature".
| sheepscreek wrote:
| Would love to take a look at your library.
| FiatLuxDave wrote:
| Not the poster above, but as someone who also has a copy
| of Ignition! in their library, I think you might enjoy
| the pdf version:
|
| https://library.sciencemadness.org/library/books/ignition
| .pd...
| grues-dinner wrote:
| Neither of the hypergolics described in _Command and
| Control_ seem chill either: the fuel reacts with
| atmospheric water and oxygen, the oxidizer is in the
| highest category of poison
| (https://www.penguinrandomhouse.co.za/extracts/command-
| and-co...).
|
| Indeed there's no such thing as a free launch, and that
| _is_ rocket science.
| IlikeKitties wrote:
| I mean, it's expensive but there's nothing that can happen,
| they just stop working the nanosecond the environment isn't
| just right.
| Cthulhu_ wrote:
| It'll be expensive, but will it be more expensive than
| the costliest disaster ever, Chernobyl, which apparently
| cost (is costing) $700 billion to contain / clean up?
| IlikeKitties wrote:
| No,... so?
| _joel wrote:
| That's not what they're doing though. Reducing manifolds
| actually improves the durability.
| GMoromisato wrote:
| You could probably summarize the history of bridge-building
| as "keep subtracting things until they don't stand up
| anymore."
|
| Building bridges (and large structures in general) has
| always been about the tension between over-engineering (for
| safety) and under-engineering (for cost/aesthetics).
|
| The Brooklyn Bridge is massive; they'd never built a bridge
| like that so they over-engineered it. But once they saw
| that it was more than strong enough to stand up, the next
| bridge was lighter. And the next one after that was even
| lighter. And so on, until a bridge collapses because some
| new factor came into play (e.g., harmonic resonance).
|
| Source: To Engineer Is Human by Henry Petroski--one of my
| favorite engineering books.
| cjbgkagh wrote:
| Not read the book but I thought the Brooklyn Bridge was
| over specified on the wire strength because they knew the
| corrupt supplier would circumvent quality control to
| supply them with substandard material.
| drob518 wrote:
| When I was an engineering summer intern at HP, they had
| all the interns do a side project of building a bridge
| (model sized). The designs would be judged by stacking
| bricks on the bridges and then dividing the max count of
| bricks before failure by the weight of the bridge. Most
| interns, myself included, over engineered our designs.
| One intern "got it" and submitted a bridge that was built
| out of just a few pieces of balsa wood. It only held one
| or two bricks before snapping, but it was ultra-light and
| won the competition. That exercise always stayed with me.
| Engineers always need to focus on the correct priorities
| and understand when "enough is enough."
| vjvjvjvjghv wrote:
| You should be keen on that idea. Simpler designs are
| usually more reliable. And a fusion reactor doesn't really
| blow up. It's hard enough to make it do something.
| andrepd wrote:
| Fusion is incredibly safe with none of the risks of runaway
| reactions like in fission.
| idiotsecant wrote:
| Raptor 3 really is quite an achievement. Good on them.
| sheepscreek wrote:
| Wow - beautiful. So there is hope! As someone unfamiliar with
| the challenges of mechanical engineering, I've often wondered
| at the complexity of fusion reactors. This picture puts a lot
| into perspective. Thanks for sharing!
| api wrote:
| Current fusion reactors are also studded with a ton of
| sensors and adjustments and injection ports and such that
| might not be present in a production reactor. They are
| experimental platforms, more like scientific instruments
| for studying the problem domain than production systems.
| pengaru wrote:
| Is that an actual honest photo? The first two seem fully
| equipped including what seems to be shielded wiring
| harnesses. #3 looks totally devoid of any electronics.
|
| disclaimer: I don't follow this stuff at all. It just looks
| like a b.s. photo deliberately exaggerating how simplified #3
| is vs. the others to this grease monkey.
| jcims wrote:
| Ready to rock(et)
|
| https://x.com/gwynne_shotwell/status/1821674726885924923?s=
| 4...
| mjamesaustin wrote:
| IIRC not only did they remove many parts completely, but
| others have been integrated into the interior, which makes
| repair harder but will improve reliability since they are
| no longer exposed.
| LeifCarrotson wrote:
| In my experience doing plumbing/hydraulics/pneumatics for
| industrial equipment, the first generation of a new product
| always looks way more complex than later versions. But I'm not
| sure they're actually more complex, they're often using a
| smaller variety of more flexible "industrial Lego" rather than
| custom, unique parts that are harder to extend or modify.
|
| Yeah, a single welded tube of the right diameter that necks
| down just so in that one spot to prevent cavitation, which has
| that sweeping multi-planar bend to just barely sneak through
| that obstruction, will look neat and tidy to a casual observer.
| Conversely, a stack of triclamp flanges, a straight length of
| pipe that shoots way out away from the guts of the equipment
| before it jogs sideways and down and back in with 90 degree
| couplings and gaskets and a manual shut-off valve and a
| pressure transmitter/flow meter and a "T" with a cap (just in
| case) and a sight glass looks like an awful mess.
|
| But I can build the latter in half an hour with parts we have
| on hand. And I'm not even a fitter, I'm an engineer! And when
| you do want to add something to it, I can do that in 5 minutes.
| After observing it function through the full regime of pressure
| and flow and viscosity parameters the equipment might have to
| deal with, I can maybe generate a print for the real plumbers
| to build the former dedicated-purpose component that sets all
| the constraints in stone (or rather, in welded stainless). That
| part will be unique and inflexible, embedding all the
| restrictions and history and test results and design decisions
| into a component that looks deceptively smooth to a layman's
| eyes.
|
| Is that simpler? I suppose it depends on your perspective.
| HPsquared wrote:
| It's a bit like interpreted code vs optimized machine code.
| jeffbee wrote:
| W7-X looks insane because its configuration was discovered by
| a computer pursuing a numerical optimization. We don't have
| any sound reasons to believe the next one will be simpler.
| empath75 wrote:
| The real problem with fusion power is that even if they figure
| it out, it still won't be cost competitive with solar and wind.
|
| Economically all the cost of building a "boil some water and
| turn some turbines" plant is _already_ in the "boiling some
| water and turning some turbines" part of the generation, and
| even if the heat part of it was _free_, the rest of it would be
| too expensive to bother building a plant for it, compared to
| just building solar and wind generation and some better
| batteries.
| ericd wrote:
| True if you look at the cost to build the plant, but it's
| hard to colocate enough solar with heavy users, land near
| there is expensive, and transmission capacity is pretty hard
| to get built, so something very power dense with a small
| footprint is helpful. I haven't dug into the numbers, so I
| could very well be wrong that it pencils out when you
| consider those.
|
| And there are efforts to make building out transmission and
| interconnecting with the grid more streamlined, so maybe some
| of those problems will be gone by the time fusion's ready.
|
| Someone said recently that it's nicer to have bad laws and
| good tech than a bad tech and good laws, solar+storage seems
| like it's in the former now, and if we can clear the
| bureaucratic hurdles, we'll see it boom here like we've seen
| elsewhere.
| JumpCrisscross wrote:
| > _real problem with fusion power is that even if they figure
| it out, it still won 't be cost competitive with solar and
| wind_
|
| This is difficult to say when comparing an emerging
| technology with an established technology in an emerging
| economy.
|
| Based on every historical prior, it would be surprising if
| there weren't diminishing returns to solar and wind. And I
| wouldn't underestimate the degree to which power is, in part,
| fashion. Today we value emissions. Tomorrow it may be
| preserving and expanding wild spaces.
|
| On a practical level, fusion research doesn't compete with
| solar and wind deployment. Pursuing both is optimal.
| vilhelm_s wrote:
| Batteries are nowhere near that cheap.
|
| Currently the cheapest non-intermittent energy source is gas;
| solar costs about half as much, and nuclear costs 50% more
| than gas [0]. Battery storage is currently competitive with
| gas for storing around 4 hours of electricity [1].
|
| If we would want to replace the baseload with solar +
| batteries we would need to store 12 hours instead, during the
| dark half of the day, so it would cost 3x as much, 200% more
| than gas.
|
| Maybe we can hope for battery prices to drop, but
| extrapolating from a Wright's law curve, for them to become
| cheaper by a factor of 3 we need to produce 32 times as many
| of them [1, again], it won't happen in the near future.
|
| [0] https://www.eia.gov/outlooks/aeo/electricity_generation/p
| df/... [1] https://www.lesswrong.com/posts/mnaEgW9JgiochnES2/
| 2024-was-t...
| constantcrying wrote:
| These reactors are build for research, so presumably they need
| to be more modular, have more measuring components and be more
| accessible for changes.
| vjvjvjvjghv wrote:
| That's how it goes most of the time. First you have to make it
| work somehow, often in a very complex way. Once you have
| something that works, either you can strip away a lot or the
| components get commoditized and you can buy them in a nice
| package. A lot of our devices are super complex but you can
| build a device without much knowledge because the complexity is
| hidden away in nicely packaged components.
| alpineman wrote:
| Old article, from June...don't get me excited
| brohee wrote:
| Does it kill the idea of a tokamak as an energy production
| device? As in a stellarator proving the much more promising
| design...
| Lev1a wrote:
| 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.
| Miraste wrote:
| 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.
| cyberax wrote:
| 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.
| HarHarVeryFunny wrote:
| Perhaps, unless you fall prey to the sunk cost fallacy and have
| already spent a bazillion dollars on generations of tokamaks!
| runxel wrote:
| 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)
| waterheater wrote:
| 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
| vjvjvjvjghv wrote:
| 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.
| wedn3sday wrote:
| I've always been somewhat partial to the stellarator design, I
| mean a big plasma donut is cool and all, but what if we twisted
| it around a whole bunch first!?
| cgannett wrote:
| mmmm plasma cruller uhuhuhuhuhu
|
| -Homer Simpson
| HarHarVeryFunny wrote:
| I think gravitational confinement is the way to go - it's the
| only operationally proven design!
|
| Gotta think big!
| exe34 wrote:
| You only need one at that point!
| ars wrote:
| It has density issues though. If you had a piece of the sun
| the size of a huge power plant - like enormous, the power
| output would be too low to be useful.
| grumbelbart wrote:
| Mandatory: We should build it in space and beam the
| electricity back to earth using electromagnetic waves. We
| could collect those using solar cells. And then get rid of
| the plant and use the sun instead.
| bradleyy wrote:
| _In any future fusion power plant, a plasma with a high triple
| product must be maintained for long periods._
|
| I love vague terms like "long periods". Long compared to the
| Planck length? Geological time? Is the advertised 43 seconds
| almost there or "off by 17 orders of magnitude?"
| dmbche wrote:
| I believe it's "for as long as the reactor is to be operating",
| and they contrast that with the previous longest times being
| less than 45 seconds.
| Analemma_ wrote:
| I thought the expectation was that actually-operating fusion
| plants would operate in pulses rather than continuously, but
| I could be misremembering.
| smallerize wrote:
| Toroidal reactors have to operate in pulses. Stellarators
| can be operated in steady-state (although sometimes they
| are pulsed to achieve higher energy).
| riffraff wrote:
| But don't you need to "refuel" now and then?
| tetha wrote:
| W7x has a pellet injection system now.
|
| This is shared in the better article here:
| https://www.ipp.mpg.de/5532945/w7x
|
| > During the record-setting experiment, about 90 frozen
| hydrogen pellets, each about a millimeter in size, were
| injected over 43 seconds, while powerful microwaves
| simultaneously heated the plasma. Precise coordination
| between heating and pellet injection was crucial to
| achieve the optimal balance between heating power and
| fuel supply.
| Tuna-Fish wrote:
| Refueling is not why tokamaks are pulsed.
|
| A smooth toroidal magnetic field cannot confine plasma.
| The field at the outer side (further away from axis) are
| spread more widely and weaker than in the inner side. In
| a very short time, this will cause ions to drift out of
| confinement at the outer side. The solution is to produce
| a twisted, helical field, where the field lines go in
| circles in both directions of the toroid simultaneously,
| like the stripes of a candy cane in the bend.
|
| Different reactor designs have different solutions to
| this. Tokamaks use a solenoid to drive a strong toroidal
| current in the plasma. This, in turn, causes a poloidal
| magnetic field, which provides the second half of the
| field needed for confinement. But this only works when
| magnetic field of the solenoid coil is varying smoothly
| over time in a single direction. Eventually, you hit some
| limit in your ability to do that, at which point you lose
| your ability to confine the plasma and the pulse ends.
|
| Stellarators do not have this issue. They get the full
| field geometry needed from their primary field, by
| twisting it around the toroid in a very complex path. The
| downside is that they are much more difficult to design
| and build.
| rnhmjoj wrote:
| Tokamaks can also be operated in steady-state, at least
| theoretically. The reason a tokamak is pulsed is due to
| the fact the toroidal current is driven inductively, so
| there is a limit to how long you can keep increasing the
| current in the central solenoid. However there are other
| methods, for example, neutral beam injection and electron
| cyclotron current drive. You can even exploit the
| bootstrap current (self-generated by collisional
| processes in the plasma) to obtain a near 100% non-
| inductive toroidal plasma (this is called "advanced
| tokamak" regime).
|
| Anyway, the older generation of devices was pulsed for
| engineering reasons (like non-superconducting coils
| getting too hot). The current generation of device is
| solving most of these and is limited by MHD instabilities
| alone (neoclassical tearing modes, mostly), if we can get
| active control mechanism working, then will be finally
| approach the long-pulse or steady-state regime.
| go_elmo wrote:
| Its implict by the context. The co text is SOTA fusion
| research. One can never fully define everything.
| pama wrote:
| I agree vague language in popular press is sometimes annoying.
|
| "Off by 17 orders of magnitude" would be off by 136 billion
| years, so not that much for sure. Assuming you want to be able
| to test the plant and or maintain it once per year, 43 seconds
| is less than 6 orders of magnitude off. The jump was more than
| a full order of magnitude compared to past records, so another
| handful such developments and we are there.
| Retric wrote:
| Even 1 hour of stability with a relatively short restart
| period (under 5 minutes) would be fine with a battery system
| assuming the rest of the power plant was cheap enough to
| build and operate.
|
| Nuclear already gets taken offline for several weeks for
| refueling, but redundancy covers such issues.
| rnhmjoj wrote:
| Long compared to the current generation of experiments. JET
| pulses lasted a couple of seconds, an actual power plant might
| be more like a couple of hours or even a steady-state.
| idiotsecant wrote:
| Oh, I see the confusion. A long period means 'not a short
| period'. Hope that helps!
| tgtweak wrote:
| This article has zero quantifiable information in it aside from
| the duration... which has no context. Who's recordkeeping this
| stuff? What are the other results so far? What is the tipping
| point where it is net positive? how long does it need to sustain
| a net positive fusion reaction to produce sufficient power for
| grid consumption? Are there other losses (thermal generation
| inefficiencies) that make the target even farther than energy-
| in<energy-out?
| tgtweak wrote:
| Here is an actual article with some context - and a reality
| check that other experimental reactors in the past have
| sustained similar triple product for longer durations...
| https://www.ipp.mpg.de/5532945/w7x
| i_am_proteus wrote:
| >The fact that W7-X results are on a par with JET is
| remarkable because JET had three times the plasma volume of
| Wendelstein 7-X.
|
| What's important here is that W 7-X is a _stellarator_ , a
| different type of fusion reactor from almost all prior
| reactors (they are tokamaks), with a smaller volume than the
| co-record holder.
|
| That a stellarator gets these results with a much smaller
| fusion volume is promising for the performance of future
| larger stellarators, since fusion reactors typically become
| more efficient as they get larger.
| tgtweak wrote:
| All good information, entirely missing from the original
| article -
| johannes1234321 wrote:
| > from almost all prior reactors (they are tokamaks)
|
| Tokamak and Stllerator are about equally old, 1953 vs 1954,
| while both types where for a period developed in secrecy
| behind either side of the iron curtain till end of the
| 1960ies where collaboration started.
|
| IPP was founded in 1960 (by, among others, my dad) and
| focussed on Stllerator since then (while collaborating in
| JET and ITER around their tokamak projects)
| colechristensen wrote:
| >What is the tipping point where it is net positive?
|
| There are several interesting net positive tipping points
| depending on where you draw the boundary that energy in and
| energy out cross. We're still in the earlier stages of net
| positive where the boundary is quite small and little
| consideration is being given to the part of the process where
| electrons get pushed around in a power grid.
| cubefox wrote:
| The article links to the original source, which has more details:
|
| https://www.ipp.mpg.de/5532945/w7x
| chris_va wrote:
| A better link: https://www.ipp.mpg.de/5532945/w7x?c=5481737
|
| (there is some irony in using the iter.org link for a stellarator
| announcement)
|
| 1.8GJ over 360 seconds, beta of 0.03
| perihelions wrote:
| > _" 1.8GJ over 360 seconds"_
|
| Not sure if this is contextually obvious to practitioners, but
| that figure is the _" Energy turnover"_ / _" is calculated as
| the product of injected heating power and plasma duration"_.
| sheepscreek wrote:
| TL;DR - Looks dangerous, but is it? (open question) Can we
| quantify it or at least make it more tangible?
|
| God, this contraption appears to be the kind of thing I wouldn't
| trust my life with. Every time I look at a fusion reactor, it
| seems far more dangerous than my hobby lab, failing to inspire
| any confidence. The numerous moving parts create an equal number
| of potential points of failure. In contrast, a nuclear reactor
| doesn't have to contend with plasma gases hotter than the Sun,
| contained within an artificial bubble solely through the
| assistance of electromagnetic radiation.
|
| I've often tried to imagine the worst case scenario, but I am
| limited by my knowledge on the subject. What kind of damage can
| hot plasma at a few million degree C do?
|
| On one hand, the plasma is hotter than anything on earth created
| by mankind. Then I believe there's also a significant number of
| wild neutrons shooting around which can cause havoc in their own
| right, if not contained. But on the other hand, unlike an
| uncontrolled chain reaction, without a source of heat, the whole
| operation shuts off by itself. I'm probably wrong about a few
| assumptions here but this is what I often find myself wondering.
| Workaccount2 wrote:
| I'd imagine that these research reactors are chock full of
| "adjustable parameter" parts and modular assemblies.
|
| Once they get everything dialed in, they can make a static
| purpose built machine with dramatically less complexity.
| Generally with research machines they are very unwieldy while
| still being dialed in.
| thinkcontext wrote:
| That fusion reactions are so difficult to get started makes the
| reactors very safe because failure makes them stop. So, if you
| lose magnetic confinement the reaction stops. The reactor may
| be damaged but that's it.
|
| This is unlike fission reactors, where a failure causes
| reactivity to increase. That causes meltdown and the
| possibility of explosion and all the nasty radioactive
| contamination.
| saddat wrote:
| Some charts : https://youtu.be/ZOZ6p2o6O14
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