19 ms·

Successful second round of fusion experiments with Wendelstein 7-X

531 points by mrfusion 8y ago

chiefalchemist 8y ago
"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?
- Tepix 8y ago
  There's still ways to go. If they manage the same confinement as a tokamak they (hope to) have the advantage of continuous operation.
- maxxxxx 8y ago
  I am not an expert but from what I have read there are still a lot of unknowns in plasma physics and fusion so it makes sense to tackle fusion from a lot of different angles and not pick a winner already. In the end what's needed is more money for research. It'a s little sad that people are complaining about the high cost of ITER while spending multiples of that for military. Fusion may be a big contributor for peace in the future if it reduces the need for fighting about access to oil.
- theresistor 8y ago
  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 8y ago
    Fair enough. And I agree. However, to be clear, that's __not__what this article says. Per the quote I pulled.
    - chiefalchemist 8y ago
      Down voted __again__ for stating a fact. Only on HN. And I thought CNN was bad.
    - aqme28 8y ago
      I think you're misinterpreting the quote, and that's probably why you were downvoted.
  - pfdietz 8y ago
    Fusion power is not critical to long term sustainability. There are perfectly adequate, even superior, alternatives. Fusion has inherent problems that, in my strong opinion, are going to render it uncompetitive against these alternatives.
  - drjesusphd 8y ago
    Fusion is only necessary for long-term sustainability if you're talking about interstellar travel (and even then, fission may be fine). There's a real physical ceiling to how much power can be consumed on Earth's surface, regardless of its source.
- aqme28 8y ago
  Why is this not important? Tokamaks are "better" right now mostly just because they have had a lot more time and energy invested in them. We need stellarator experiments to see if stellarators like this one might be valid. > something that's important in the immediate That's not easy to find in fusion research.
- avar 8y ago
  Given the importance of transportation for society, shouldn't this effort going into "automobiles" go towards better wooden wheels for horse-drawn carriages?
- alexgmcm 8y ago
  From my classes some years ago IIRC the main benefit of the Stellarator was the lack of a plasma current which is no longer needed for plasma heating due to advances in neutral beam injection technologies. The plasma current seems to create some instabilities so we may be able to achieve better confinement with a device that doesn't have one. I would also agree with the other comments that we can't afford to put all our eggs into one basket - we spend a pitifully small amount on fusion research.
  - cygx 8y ago
    The promise of stellarators is continuous operation, whereas tokamaks traditionally rely on inductive pulses for the two-fold purpose of confinement and heating.
  - pfdietz 8y ago
    The big advantage of stellarators vs. tokamaks is their lack of disruptions. Tokamak disruptions are a very serious problem that, if not well-solved, promise to put tokamaks into the technology garbage can. A disruption can, in the worst case, generate runaway relativistic electron beams that can melt holes through the first wall. The first and primary goal of ITER is to show that the disruption problem can be and has been solved. If they don't do this, ITER will never be allowed to operate with a DT plasma. And they are still scrambling to solve the problem.
    - lambdadmitry 8y ago
      Are talking about ELMs? Isn't it a basically solved problem then? I was under impression that between KSTAR's active field disruption coils and pellet injection they are more or less controlled (and we'll have confirmation from MAST Upgrade quite soon). Or am I wrong?
      - pfdietz 8y ago
        No, disruptions are catastrophic events where confinement is lost very rapidly. As the plasma cools an electric field builds up from the decaying current, and this field can accelerate runaway electrons in narrow beams to relativistic energies. Worst case >70% of the stored magnetic energy from the current in the plasma gets dumped into these electrons. If they hit the wall they can explode a hole in it. https://en.m.wikipedia.org/wiki/Tokamak#Plasma_disruptions https://en.m.wikipedia.org/wiki/Tokamak#Plasma_disruptions
- _ph_ 8y ago
  Wendelstein is clearly targeted at research leading to fusion. It is just, that the Wendelstein 7-X experiment is purely limited to reasearching plasma containment. Once this experiment is concluded successfully - and all the results are very encouraging, implementing actual fusion would be the purpose of a successor to 7-X.
- scarejunba 8y ago
  You have not adequately argued that a Depth-First Search is superior to a Breadth-First Search here (or that the balance here is wrong). The value you describe is the goal value which influences the search strategy not very much.
- gus_massa 8y ago
  Nobody knows if it's easier to build a commercial fusion power plant with the tokamak design or with the stellarator design or with another of less known competing designs or with another design that nobody has imagined yet. Moreover, perhaps some of these design (including thetokamak and stellarator) perhaps are nice for a lab demo or a model plant that doesn't break even or a tiny scale plant, but they may not scale to a full power plant that can produce energy at a useful level. (That's why this is called "research", you don't know if it will work.) So they are following the usual path that is allocating some money to a few competing groups with different ideas and hope that one of them will get something useful. The problem is how to distribute the money between the alternative approach, and the method is a mix of analysis of the proposals, the intermediate results, grantbaits, and politics.
  - brian_cunnie 8y ago
    Agreed — the problem is that, from an energy perspective, it "doesn't break even". Zach Hartwig of MIT has an excellent video [0] of how to evaluate announcements of nuclear fusion advances. The big problem is breaking even. There are other problem, too: plasma containment, etc. [0] https://www.youtube.com/watch?v=L0KuAx1COEk https://www.youtube.com/watch?v=L0KuAx1COEk
  - pfdietz 8y ago
    Neither tokamaks nor stellarators appear promising for reaching commercial viability. Both are very complex, very expensive, and will have very poor power density compared to fission reactors (making them much larger for a given power output). It's difficult to see how they could approach the levelized cost of energy that solar and wind have already achieved, never mind the costs of these decades hence.
- 08-15 8y ago
  60 years ago, when nobody knew anything about fusion (so not a very different situation from today...), the stellarator was the favored design. The advantages are obvious on paper (which is all they had back then): continuous operation, more stable plasma. But then the Russians built a small tokamak and it worked surprisingly well. So the whole world went "given the importance of fusion, shouldn't the time and effort being put into stellarators be devoted to something that's important in the immediate?" and started working on tokamaks. 60 years later, tokamaks still haven't been turned into power plants. Things were harder than imagined, and much more expensive, too. It doesn't look as if ITER will ever yield something practical. Maybe the MIT guys can make the Arc Reactor a reality; but all they have right now is... exactly, paper. (The whole world? No! A tiny village outside Munich built the Wendelstein series of stellarators...)
ttul 8y ago
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 8y ago
  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.
  - adrianN 8y ago
    Fusion research is chronically underfunded. We actually have made surprising progress despite basically not funding research at all.
  - cygx 8y ago
    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_fusion_budget_vs._1976_ERDA_plan.png https://commons.wikimedia.org/wiki/File:U.S._historical_fusi... ). 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.
saganus 8y ago
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.
- nine_k 8y ago
  I can imagine that this is just the neutron flux picture. The neutron streams should pass the walls pretty well (unfortunately), so registering it should not be hard.
  - saganus 8y ago
    I am obviously very uninformed about this, but in the picture I'm referring to [0] you can see the walls in pretty good detail, so I assumed it was an optical picture. No idea if a neutron flux picture would provide these details or not. [0] https://www.ipp.mpg.de/4550362/original-1543230147.jpg?t=eyJ3aWR0aCI6MTQwMCwib2JqX2lkIjo0NTUwMzYyfQ==--725ae5efe9c24f625450fa8f0143a53cb5d8a7dc https://www.ipp.mpg.de/4550362/original-1543230147.jpg?t=eyJ...
  - ben_w 8y ago
    I doubt that. High energy neutrons are difficult to diffract (so no lenses), reflect more like light on fog than light on tin foil (so no mirrors) and pass through material too easily for a pinhole lens to be plausible. I think you have to go to quite low energies (per neutron, not flux) for neutron optics to be a thing. Neutron cameras use collimated neutron sources to get around this, but that option isn’t available here: https://en.m.wikipedia.org/wiki/Neutron_imaging#Neutron_camera_(DR_System) https://en.m.wikipedia.org/wiki/Neutron_imaging#Neutron_came...
    - nine_k 8y ago
      You don't need to diffract the neutron flux. Instead, you can wrap (low-res) neutron-sensitive material around the stellarator tube. IDK now well would conventional photodiode or CCD work under high magnetic field, though.
nine_k 8y ago
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.
- bicubic 8y ago
  This doesn’t solve the fact that a single fusion pulse (all existing reactors are pulsed) currently consumes more energy than it produces.
  - deleted 8y ago
    [deleted]
  - nine_k 8y ago
    I remember hearing about break-even events for a few years. E.g. from 2014: https://www.nature.com/news/laser-fusion-experiment-extracts-net-energy-from-fuel-1.14710 https://www.nature.com/news/laser-fusion-experiment-extracts... A design that produces e.g. 2x the energy it consumes for the startup could be viable, even if pulsed (running minutes, not months).
    - Chemiseblanc 8y ago
      IIRC They were able to get net energy from the fuel versus the energy of the x-rays used to ignite it. But not in terms of the energy of the lasers used to create the x-rays by vaporizing the fuel pellet.
emilfihlman 8y ago
The name is really scifi. I love it!
tlb 8y ago
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.)
- rzzzt 8y ago
  David Gelernter has a book on (mostly? not sure if I remember correctly) industrial and software design, in which he brings up the bakelite telephone as an example of such an object. Weird shape - check, functional - check (the handset's size and placement matches the distance between the ears and the mouth). It became a literal icon of itself. https://en.wikipedia.org/wiki/Model_302_telephone https://en.wikipedia.org/wiki/Model_302_telephone
- MacroChip 8y ago
  https://en.m.wikipedia.org/wiki/Evolved_antenna https://en.m.wikipedia.org/wiki/Evolved_antenna looks weird. Source 1 has another image of a more complex antenna.
  - magnat 8y ago
    Both images for lazy: https://i.imgur.com/ROhfMXb.jpg https://i.imgur.com/ROhfMXb.jpg
- pjungwir 8y ago
  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.
ChuckMcM 8y ago
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 8y ago
  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.
samirm 8y ago
Awesome progress, but I feel like the stellerator design won't be scalable/feasible :/
deleted 8y ago
[deleted]
torgian 8y ago
In the words of peter griffin, why aren’t we funding this more?
beambot 8y ago
> 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 8y ago
  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 8y ago
I found this panorama shot on their home page: https://www2.ipp.mpg.de/ippcms/eng/externe_daten_en/panoramaw7x/ https://www2.ipp.mpg.de/ippcms/eng/externe_daten_en/panorama...
zeristor 8y ago
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...

531 points by mrfusion 8y ago

"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?

Tepix 8y ago
There's still ways to go. If they manage the same confinement as a tokamak they (hope to) have the advantage of continuous operation.
maxxxxx 8y ago
I am not an expert but from what I have read there are still a lot of unknowns in plasma physics and fusion so it makes sense to tackle fusion from a lot of different angles and not pick a winner already. In the end what's needed is more money for research. It'a s little sad that people are complaining about the high cost of ITER while spending multiples of that for military. Fusion may be a big contributor for peace in the future if it reduces the need for fighting about access to oil.
theresistor 8y ago
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 8y ago
  Fair enough. And I agree. However, to be clear, that's __not__what this article says. Per the quote I pulled.
  - chiefalchemist 8y ago
    Down voted __again__ for stating a fact. Only on HN. And I thought CNN was bad.
  - aqme28 8y ago
    I think you're misinterpreting the quote, and that's probably why you were downvoted.
- pfdietz 8y ago
  Fusion power is not critical to long term sustainability. There are perfectly adequate, even superior, alternatives. Fusion has inherent problems that, in my strong opinion, are going to render it uncompetitive against these alternatives.
- drjesusphd 8y ago
  Fusion is only necessary for long-term sustainability if you're talking about interstellar travel (and even then, fission may be fine). There's a real physical ceiling to how much power can be consumed on Earth's surface, regardless of its source.
aqme28 8y ago
Why is this not important? Tokamaks are "better" right now mostly just because they have had a lot more time and energy invested in them. We need stellarator experiments to see if stellarators like this one might be valid. > something that's important in the immediate That's not easy to find in fusion research.
avar 8y ago
Given the importance of transportation for society, shouldn't this effort going into "automobiles" go towards better wooden wheels for horse-drawn carriages?
alexgmcm 8y ago
From my classes some years ago IIRC the main benefit of the Stellarator was the lack of a plasma current which is no longer needed for plasma heating due to advances in neutral beam injection technologies. The plasma current seems to create some instabilities so we may be able to achieve better confinement with a device that doesn't have one. I would also agree with the other comments that we can't afford to put all our eggs into one basket - we spend a pitifully small amount on fusion research.
- cygx 8y ago
  The promise of stellarators is continuous operation, whereas tokamaks traditionally rely on inductive pulses for the two-fold purpose of confinement and heating.
- pfdietz 8y ago
  The big advantage of stellarators vs. tokamaks is their lack of disruptions. Tokamak disruptions are a very serious problem that, if not well-solved, promise to put tokamaks into the technology garbage can. A disruption can, in the worst case, generate runaway relativistic electron beams that can melt holes through the first wall. The first and primary goal of ITER is to show that the disruption problem can be and has been solved. If they don't do this, ITER will never be allowed to operate with a DT plasma. And they are still scrambling to solve the problem.
  - lambdadmitry 8y ago
    Are talking about ELMs? Isn't it a basically solved problem then? I was under impression that between KSTAR's active field disruption coils and pellet injection they are more or less controlled (and we'll have confirmation from MAST Upgrade quite soon). Or am I wrong?
    - pfdietz 8y ago
      No, disruptions are catastrophic events where confinement is lost very rapidly. As the plasma cools an electric field builds up from the decaying current, and this field can accelerate runaway electrons in narrow beams to relativistic energies. Worst case >70% of the stored magnetic energy from the current in the plasma gets dumped into these electrons. If they hit the wall they can explode a hole in it. https://en.m.wikipedia.org/wiki/Tokamak#Plasma_disruptions https://en.m.wikipedia.org/wiki/Tokamak#Plasma_disruptions
_ph_ 8y ago
Wendelstein is clearly targeted at research leading to fusion. It is just, that the Wendelstein 7-X experiment is purely limited to reasearching plasma containment. Once this experiment is concluded successfully - and all the results are very encouraging, implementing actual fusion would be the purpose of a successor to 7-X.
scarejunba 8y ago
You have not adequately argued that a Depth-First Search is superior to a Breadth-First Search here (or that the balance here is wrong). The value you describe is the goal value which influences the search strategy not very much.
gus_massa 8y ago
Nobody knows if it's easier to build a commercial fusion power plant with the tokamak design or with the stellarator design or with another of less known competing designs or with another design that nobody has imagined yet. Moreover, perhaps some of these design (including thetokamak and stellarator) perhaps are nice for a lab demo or a model plant that doesn't break even or a tiny scale plant, but they may not scale to a full power plant that can produce energy at a useful level. (That's why this is called "research", you don't know if it will work.) So they are following the usual path that is allocating some money to a few competing groups with different ideas and hope that one of them will get something useful. The problem is how to distribute the money between the alternative approach, and the method is a mix of analysis of the proposals, the intermediate results, grantbaits, and politics.
- brian_cunnie 8y ago
  Agreed — the problem is that, from an energy perspective, it "doesn't break even". Zach Hartwig of MIT has an excellent video [0] of how to evaluate announcements of nuclear fusion advances. The big problem is breaking even. There are other problem, too: plasma containment, etc. [0] https://www.youtube.com/watch?v=L0KuAx1COEk https://www.youtube.com/watch?v=L0KuAx1COEk
- pfdietz 8y ago
  Neither tokamaks nor stellarators appear promising for reaching commercial viability. Both are very complex, very expensive, and will have very poor power density compared to fission reactors (making them much larger for a given power output). It's difficult to see how they could approach the levelized cost of energy that solar and wind have already achieved, never mind the costs of these decades hence.
08-15 8y ago
60 years ago, when nobody knew anything about fusion (so not a very different situation from today...), the stellarator was the favored design. The advantages are obvious on paper (which is all they had back then): continuous operation, more stable plasma. But then the Russians built a small tokamak and it worked surprisingly well. So the whole world went "given the importance of fusion, shouldn't the time and effort being put into stellarators be devoted to something that's important in the immediate?" and started working on tokamaks. 60 years later, tokamaks still haven't been turned into power plants. Things were harder than imagined, and much more expensive, too. It doesn't look as if ITER will ever yield something practical. Maybe the MIT guys can make the Arc Reactor a reality; but all they have right now is... exactly, paper. (The whole world? No! A tiny village outside Munich built the Wendelstein series of stellarators...)

ttul 8y ago

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 8y ago
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.
- adrianN 8y ago
  Fusion research is chronically underfunded. We actually have made surprising progress despite basically not funding research at all.
- cygx 8y ago
  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_fusion_budget_vs._1976_ERDA_plan.png https://commons.wikimedia.org/wiki/File:U.S._historical_fusi... ). 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.

saganus 8y ago

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.

nine_k 8y ago
I can imagine that this is just the neutron flux picture. The neutron streams should pass the walls pretty well (unfortunately), so registering it should not be hard.
- saganus 8y ago
  I am obviously very uninformed about this, but in the picture I'm referring to [0] you can see the walls in pretty good detail, so I assumed it was an optical picture. No idea if a neutron flux picture would provide these details or not. [0] https://www.ipp.mpg.de/4550362/original-1543230147.jpg?t=eyJ3aWR0aCI6MTQwMCwib2JqX2lkIjo0NTUwMzYyfQ==--725ae5efe9c24f625450fa8f0143a53cb5d8a7dc https://www.ipp.mpg.de/4550362/original-1543230147.jpg?t=eyJ...
- ben_w 8y ago
  I doubt that. High energy neutrons are difficult to diffract (so no lenses), reflect more like light on fog than light on tin foil (so no mirrors) and pass through material too easily for a pinhole lens to be plausible. I think you have to go to quite low energies (per neutron, not flux) for neutron optics to be a thing. Neutron cameras use collimated neutron sources to get around this, but that option isn’t available here: https://en.m.wikipedia.org/wiki/Neutron_imaging#Neutron_camera_(DR_System) https://en.m.wikipedia.org/wiki/Neutron_imaging#Neutron_came...
  - nine_k 8y ago
    You don't need to diffract the neutron flux. Instead, you can wrap (low-res) neutron-sensitive material around the stellarator tube. IDK now well would conventional photodiode or CCD work under high magnetic field, though.

nine_k 8y ago

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.

bicubic 8y ago
This doesn’t solve the fact that a single fusion pulse (all existing reactors are pulsed) currently consumes more energy than it produces.
- deleted 8y ago
  [deleted]
- nine_k 8y ago
  I remember hearing about break-even events for a few years. E.g. from 2014: https://www.nature.com/news/laser-fusion-experiment-extracts-net-energy-from-fuel-1.14710 https://www.nature.com/news/laser-fusion-experiment-extracts... A design that produces e.g. 2x the energy it consumes for the startup could be viable, even if pulsed (running minutes, not months).
  - Chemiseblanc 8y ago
    IIRC They were able to get net energy from the fuel versus the energy of the x-rays used to ignite it. But not in terms of the energy of the lasers used to create the x-rays by vaporizing the fuel pellet.

emilfihlman 8y ago

The name is really scifi. I love it!

tlb 8y ago

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.)

rzzzt 8y ago
David Gelernter has a book on (mostly? not sure if I remember correctly) industrial and software design, in which he brings up the bakelite telephone as an example of such an object. Weird shape - check, functional - check (the handset's size and placement matches the distance between the ears and the mouth). It became a literal icon of itself. https://en.wikipedia.org/wiki/Model_302_telephone https://en.wikipedia.org/wiki/Model_302_telephone
MacroChip 8y ago
https://en.m.wikipedia.org/wiki/Evolved_antenna https://en.m.wikipedia.org/wiki/Evolved_antenna looks weird. Source 1 has another image of a more complex antenna.
- magnat 8y ago
  Both images for lazy: https://i.imgur.com/ROhfMXb.jpg https://i.imgur.com/ROhfMXb.jpg
pjungwir 8y ago
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.

ChuckMcM 8y ago

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 8y ago
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.

samirm 8y ago

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

deleted 8y ago

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torgian 8y ago

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

beambot 8y ago

> 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 8y ago
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 8y ago

I found this panorama shot on their home page: https://www2.ipp.mpg.de/ippcms/eng/externe_daten_en/panoramaw7x/ https://www2.ipp.mpg.de/ippcms/eng/externe_daten_en/panorama...

zeristor 8y ago

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...