6 ms·

Just to reiterate, Wendelstein 7-X is not about fusion. 7-X is a research project about controlling a plasma. It is not meant to evaluate whether energy product

Just to reiterate, Wendelstein 7-X is not about fusion. 7-X is a research project about controlling a plasma. It is not meant to evaluate whether energy production is viable, neither is it setup to do so.

alexgmcm 8y ago
To be fair though - the stellarator design is pretty cool as it doesn't have a plasma current and nowadays we can heat the plasma via beam injection. The lack of the current might make it more stable vs. the tokamak.
- mrfusion 8y ago
  What do you mean by current?
  - gnode 8y ago
    Electric current; net momentum difference between positive and negative charges within the plasma. I.e. nuclei moving clockwise, and electrons counter-clockwise within the tokamak, or vice-versa. The plasma may have a high temperature (and thus induce fusion) without such current.
ChuckMcM 8y ago
I think that undersells it. While it is true that the 7-x is about proving the concepts of the Stellerator, you can use the plasma stream from such a device as part of an energy system.
IshKebab 8y ago
It's clearly about fusion. Maybe you meant it's not about generating power?
- blattimwind 8y ago
  No. 7-X hasn't performed any fusion at all and while they later want to use plasmas that are closer in composition to what you'd find in a fusion reactor, very little fusion will take place — intentionally, to avoid generating significant amounts of neutron radiation. It's perhaps important to point out that fusion is not difficult; it's very easy in fact. The hard part for power generation is plasma physics, i.e. being able to contain and control a plasma effectively. That's what 7-X is designed to research. If you can control a sustained plasma, fusion power is relatively easy.
  - dnautics 8y ago
    I would even dare to stop calling it plasma physics at this point, but rather plasma engineering.
    - toadworrier 8y ago
      I am no plasma physicist, but the concern I hear about fusion is that whenever we scale a system up we find the plasma is behaving in new ways, resulting in new loss mechanisms. Identifying and understanding those new behaviours sounds more like science than engineering to me. (That said, scientists frequently do engineering and engineers frequently do science; I've been on both sides of it).
  - loblollyboy 8y ago
    Yes it has. It hasn’t broken energy breakeven but fusion is definitely happening in that plasma and, for that matter, plasmas at lower temperatures, lower densities and with lower confinement times. Getting particles to fuse is pretty trivial.
    - chasil 8y ago
      Philo T. Farnsworth famously invented a fusor in 1964: https://en.wikipedia.org/wiki/Fusor https://en.wikipedia.org/wiki/Fusor He was an inventor of a variety of television technology, and I believe the designs were very similar to his fusor. Unfortunately, the design cannot be made "exothermic" IIRC, and the research ruined him financially.
- detaro 8y ago
  It explicitly has not been designed to improve fusion efficiency, but to do plasma-handling with minimal fusion happening. This way, it needs a lot less shielding than a fusion-centric experiment would need, and is thus cheaper to build and easier to maintain.
  - azernik 8y ago
    It hasn't been designed to do fusion itself, but that doesn't make it "not about fusion" - the only major application of the technology is fusion.
deleted 8y ago
[deleted]
arez 8y ago
that's not correct. It's definitely about fusion and to test a different concept as the tomahawk, the problem is that you need a self sustaining fusion and that happens at 100M°C. Of course there're lots of other experiments and interesting stuff happening, but it's also to find a viable concept to generate power (that's also why they get lots of european funding). There's a good interview with a scientist and a director from wendelstein 7-X but it's in german https://alternativlos.org/36/ https://alternativlos.org/36/
- ooopswedidit2 8y ago
  Pooohh back from a session on the water closet, dumb like me can not say that a practicable "fuzzion"-reactor did not have to work like a sink. There is the need for sized/ matching "Zu-/Ablauf" (sry, German) and an "Überlauf" and yes, (spoiler:) the fusion waste product (Neutrinos) - mega useful for projects runed by the milita...ooops! (-;
darawk 8y ago
> 7-X is a research project about controlling a plasma. Which is the primary impediment to developing viable fusion reactors. So yes, it is absolutely about fusion. We're not trying to contain plasma because we think it'd be a neat thing to do. We're trying to contain plasma because it's necessary for fusion. We already know that energy production is viable if we can solve the containment problem. Saying this project "isn't about fusion" is like saying "guns don't kill people, bullets do".
- jnxx 8y ago
  > We already know that energy production is viable if we can solve the containment problem. No. That's only a small part of the problems. What is probably a far more difficult problem is the fact that any nuclear fusion which is remotely viable in this century will use a Deuterium-Tritium reaction. And tritium is an isotope which does not occur in nature - it is unstable. Therefore tritium has to be bred, using heavy water reactors. And lots, lots, of uranium. The idea is now to breed tritium, using neutrons from nuclear fusion, and further nuclear chemistry which is supposed to happen in a breeding blanket. But this runs into an additional problem, the deuterium-tritium reaction has no neutron surplus, as uranium fission has. And in addition to the very difficult task of exfiltrating traces of Tritium, one essentially needs a breeder technology (similar to Monju in Japan), and there are huge, unsolved material sciences problems, such as constructing a large structures which withstands very strong magnetic forces, very high temperatures, and a very high neutron flux, and this of course without any elements like carbon which will become radioactively activated. Oh, and I forgot, the whole process is also unlikely to be clean, because of the breeder technology needed. And all these questions are so extremely difficult, that today's large projects, like ITER, do not even address them. More on these issues for example in the article by Michael Moyer which is contained in the page below (Michael Moyer, "Fusion's false Dawn", Scientific American 302, 50 - 57 (2010) doi:10.1038/scientificamerican0310-50 ) http://energyskeptic.com/2014/why-fusion-is-still-30-years-away/ http://energyskeptic.com/2014/why-fusion-is-still-30-years-a...
  - philipkglass 8y ago
    Tritium can be bred in any sort of fission reactor. The US has recently used light water power reactors to breed tritium for supplying the US nuclear weapons stockpile. Lithium-7 plus a high energy neutron yields tritium, helium, and a lower energy neutron. I don't know what a practically engineered system can do, but a 14.1 MeV neutron from D-T fusion formally has enough energy to transmute 5 lithium-7 nuclei into tritium and helium (each transmutation is endothermic to the tune of 2.466 MeV). I agree about the huge unsolved material science problems. I just don't think that tritium availability lies on the critical path of unsolved problems for industrial fusion power.
azernik 8y ago
And fusion is the only application of plasma containment that anyone cares about. Might as well call transistor fabrication experiments "not about computers".
wyattpeak 8y ago
As someone with little knowledge of the field or the experiment, thank you. I was mystified why the article didn't seem to mention viability.
- ygra 8y ago
  Because the article is only about the mentioned achievement. The project page of Wendelstein 7-X (https://www.ipp.mpg.de/w7x https://www.ipp.mpg.de/w7x) details what the project is about, though.

alexgmcm 8y ago

To be fair though - the stellarator design is pretty cool as it doesn't have a plasma current and nowadays we can heat the plasma via beam injection. The lack of the current might make it more stable vs. the tokamak.

mrfusion 8y ago
What do you mean by current?
- gnode 8y ago
  Electric current; net momentum difference between positive and negative charges within the plasma. I.e. nuclei moving clockwise, and electrons counter-clockwise within the tokamak, or vice-versa. The plasma may have a high temperature (and thus induce fusion) without such current.

ChuckMcM 8y ago

I think that undersells it. While it is true that the 7-x is about proving the concepts of the Stellerator, you can use the plasma stream from such a device as part of an energy system.

IshKebab 8y ago

It's clearly about fusion. Maybe you meant it's not about generating power?

blattimwind 8y ago
No. 7-X hasn't performed any fusion at all and while they later want to use plasmas that are closer in composition to what you'd find in a fusion reactor, very little fusion will take place — intentionally, to avoid generating significant amounts of neutron radiation. It's perhaps important to point out that fusion is not difficult; it's very easy in fact. The hard part for power generation is plasma physics, i.e. being able to contain and control a plasma effectively. That's what 7-X is designed to research. If you can control a sustained plasma, fusion power is relatively easy.
- dnautics 8y ago
  I would even dare to stop calling it plasma physics at this point, but rather plasma engineering.
  - toadworrier 8y ago
    I am no plasma physicist, but the concern I hear about fusion is that whenever we scale a system up we find the plasma is behaving in new ways, resulting in new loss mechanisms. Identifying and understanding those new behaviours sounds more like science than engineering to me. (That said, scientists frequently do engineering and engineers frequently do science; I've been on both sides of it).
- loblollyboy 8y ago
  Yes it has. It hasn’t broken energy breakeven but fusion is definitely happening in that plasma and, for that matter, plasmas at lower temperatures, lower densities and with lower confinement times. Getting particles to fuse is pretty trivial.
  - chasil 8y ago
    Philo T. Farnsworth famously invented a fusor in 1964: https://en.wikipedia.org/wiki/Fusor https://en.wikipedia.org/wiki/Fusor He was an inventor of a variety of television technology, and I believe the designs were very similar to his fusor. Unfortunately, the design cannot be made "exothermic" IIRC, and the research ruined him financially.
detaro 8y ago
It explicitly has not been designed to improve fusion efficiency, but to do plasma-handling with minimal fusion happening. This way, it needs a lot less shielding than a fusion-centric experiment would need, and is thus cheaper to build and easier to maintain.
- azernik 8y ago
  It hasn't been designed to do fusion itself, but that doesn't make it "not about fusion" - the only major application of the technology is fusion.

deleted 8y ago

[deleted]

arez 8y ago

that's not correct. It's definitely about fusion and to test a different concept as the tomahawk, the problem is that you need a self sustaining fusion and that happens at 100M°C. Of course there're lots of other experiments and interesting stuff happening, but it's also to find a viable concept to generate power (that's also why they get lots of european funding). There's a good interview with a scientist and a director from wendelstein 7-X but it's in german https://alternativlos.org/36/ https://alternativlos.org/36/

ooopswedidit2 8y ago
Pooohh back from a session on the water closet, dumb like me can not say that a practicable "fuzzion"-reactor did not have to work like a sink. There is the need for sized/ matching "Zu-/Ablauf" (sry, German) and an "Überlauf" and yes, (spoiler:) the fusion waste product (Neutrinos) - mega useful for projects runed by the milita...ooops! (-;

darawk 8y ago

> 7-X is a research project about controlling a plasma. Which is the primary impediment to developing viable fusion reactors. So yes, it is absolutely about fusion. We're not trying to contain plasma because we think it'd be a neat thing to do. We're trying to contain plasma because it's necessary for fusion. We already know that energy production is viable if we can solve the containment problem. Saying this project "isn't about fusion" is like saying "guns don't kill people, bullets do".

jnxx 8y ago
> We already know that energy production is viable if we can solve the containment problem. No. That's only a small part of the problems. What is probably a far more difficult problem is the fact that any nuclear fusion which is remotely viable in this century will use a Deuterium-Tritium reaction. And tritium is an isotope which does not occur in nature - it is unstable. Therefore tritium has to be bred, using heavy water reactors. And lots, lots, of uranium. The idea is now to breed tritium, using neutrons from nuclear fusion, and further nuclear chemistry which is supposed to happen in a breeding blanket. But this runs into an additional problem, the deuterium-tritium reaction has no neutron surplus, as uranium fission has. And in addition to the very difficult task of exfiltrating traces of Tritium, one essentially needs a breeder technology (similar to Monju in Japan), and there are huge, unsolved material sciences problems, such as constructing a large structures which withstands very strong magnetic forces, very high temperatures, and a very high neutron flux, and this of course without any elements like carbon which will become radioactively activated. Oh, and I forgot, the whole process is also unlikely to be clean, because of the breeder technology needed. And all these questions are so extremely difficult, that today's large projects, like ITER, do not even address them. More on these issues for example in the article by Michael Moyer which is contained in the page below (Michael Moyer, "Fusion's false Dawn", Scientific American 302, 50 - 57 (2010) doi:10.1038/scientificamerican0310-50 ) http://energyskeptic.com/2014/why-fusion-is-still-30-years-away/ http://energyskeptic.com/2014/why-fusion-is-still-30-years-a...
- philipkglass 8y ago
  Tritium can be bred in any sort of fission reactor. The US has recently used light water power reactors to breed tritium for supplying the US nuclear weapons stockpile. Lithium-7 plus a high energy neutron yields tritium, helium, and a lower energy neutron. I don't know what a practically engineered system can do, but a 14.1 MeV neutron from D-T fusion formally has enough energy to transmute 5 lithium-7 nuclei into tritium and helium (each transmutation is endothermic to the tune of 2.466 MeV). I agree about the huge unsolved material science problems. I just don't think that tritium availability lies on the critical path of unsolved problems for industrial fusion power.

azernik 8y ago

And fusion is the only application of plasma containment that anyone cares about. Might as well call transistor fabrication experiments "not about computers".

wyattpeak 8y ago

As someone with little knowledge of the field or the experiment, thank you. I was mystified why the article didn't seem to mention viability.

ygra 8y ago
Because the article is only about the mentioned achievement. The project page of Wendelstein 7-X (https://www.ipp.mpg.de/w7x https://www.ipp.mpg.de/w7x) details what the project is about, though.