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Is General Fusion and Magnetized target fusion legit?

  1. Dec 21, 2008 #1
    I just read an article in the most recent Popular Science about a company, General Fusion, claiming that they would have fusion reactors with net power in FIVE YEARS. Of course, this sent alarm bells off in my head, and I'm wondering if there is any legitimacy to what they're doing, or if they're going to get someone to invest in them and then disappear like so many other crackpots.

    Here is the wikipedia article on the technique they're using: http://en.wikipedia.org/wiki/Magnetized_target_fusion
  2. jcsd
  3. Dec 21, 2008 #2


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    Such claims set of alarm bells for me.

    Note the disclaimer on the Wikipedia MTF article: This article needs additional citations for verification. Please help improve this article by adding reliable references. Unsourced material may be challenged and removed.

    Could the Wikipedia article have been provided by someone with or associated with General Fusion?

    I guess we'll know in 5 years.

    Meanwhile - here is some information about MTF on the LANL website.

  4. Dec 24, 2008 #3
    Here is a link to the article (hopefully I am allowed to post this)


    It's kind of interesting, although I have no idea how legit nuclear fusion is.

    Last edited by a moderator: Apr 24, 2017
  5. Jan 23, 2009 #4
    They'll undoubtedly produce fusion energy, you can do this with a deuteron beam striking a tritiated target - the trick is to produce so very much fusion energy that you offset the enormous costs involved with making it in the first place. Here they will fail, unless 70+ years of work by many thousands of very smart people based on relatively simple physics and a lot of experiments is all wrong.
  6. Jan 23, 2009 #5


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    Perhaps, but GF is not a crackpot outfit. Kirkpatric of LANL, a long time MTF player, did a review for them:
    http://www.generalfusion.com/files/external_review.pdf [Broken]

    Makes sense, as LANL seems to be the govt. go to lab for MTF. They see MTF as a Lawson criterion middle ground between magnetic confinement and inertial implosion, with middling densities (10^17cm^-3), temperatures (200eV), and confinement times (microseconds) which allows them to build far more cheaply.
    Last edited by a moderator: May 3, 2017
  7. Feb 22, 2011 #6
    I have the very magazine you are speaking of right next to me and i just finished reading the article. I was thinking exactly the same thing. They have a miniature prototype already functional, but as someone else said, it produces far less energy than it consumes, about 100 trillion times less. If you want more info, check out their website at http://www.generalfusion.com/

    But yeah, so far their idea seams valid, but many scientist are waiting for that one unexpected glitch in the system that will make them have to complicate their designs and sky-rocket the price. They themselves though believe it will work eventually with enough funding, about 50 million dollars of it.

    I guess we'll just have to wait and see if this really does work. I am somewhat doubtful but i really cannot say truthfully that this will not work.
  8. Aug 4, 2011 #7
    I have no sufficient knowledge about fusion hence no opinion about their chances to produce a net energy.
    But I do have experience about shocks, mechanical engineering with big forces over short times, and precise control, as I developed hardware for crash-test, which includes reproducing precisely with big actuators the movements of an accident (fun, yes).

    So my impression for this part of their project, that is the ~220 hammers:

    They want 100m/s and this produces a shock wave at about the absolute maximum yield strength of the very best non-brittle alloys. Here I doubt because of stress concentration. But at 30m/s my parts didn't wear out, and 50m/s must be possible, so if 100m/s fail, a bigger sphere may compensate the slower hammers.

    They need around 1µs precision on the shock datum over all hammers. Using the fastest hydraulic servo-valves (do they have valves?) with 10-20ms reaction time, we achieved 100µs precision more or less, after painstaking optimization.

    But here are my two cents worth of enabling technology:
    http://saposjoint.net/Forum/viewtopic.php?f=49&t=2774 (visitors can't watch the drawings at Sapo's website, pity)
    http://www.scienceforums.net/topic/58924-magnetized-target-fusion/ (there visitors can, and my text is more concise)
    - An eddy current brake, fast and finely adjustable, to control the movement of the hammers pushed by full force
    - A fast unlocker to release the hammers within 1ms, easing subsequent control
    - Maybe a displacement sensor for the hammers. At least speed and resolution look feasible, but intuition would shout to keep shocks and optics apart.

    Marc Schaefer, aka Enthalpy
  9. Aug 5, 2011 #8


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    I would think the details of this problem have already been worked out with chemical explosive driven nuclear implosion devices, the requirements and limitations known. None of those details would be in the public domain, but perhaps a yes/no answer could be produced?
  10. Aug 5, 2011 #9
    Explosive compression of plutonium spheres is described in textbooks, at least the general idea and the detonators. Spooks nevertheless take it as an excuse to designate as secret the texts describing it.

    The very different feature is that you don't reuse a bomb, whereas General Fusion wants to make one shock a second. Explosive for instance would be difficult to replenish fast enough nor to produce at low energetic cost. As well, yield strength isn't a concern in a bomb.

    For reuse, General Fusion wants to have sort of pneumatic jackhammers. There, no permanent damage is allowed, and synchronization of slower mechanical movements is more difficult.

    And if the guys there achieve a nice compression, their design would be of no interest to ignite a bomb. Explosives are so much smaller and easier!
  11. Aug 5, 2011 #10


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    Yes of course, but a shock wave from a hammer or a charge is still a shock wave, that travels with speed x through material y, etc, etc. Before working on repeat-ability the MTF people need show that they can produce a given fusion energy once.
  12. Aug 7, 2011 #11

    From what I read too quickly, the same guys have already fused deuterium (I mean D-D, not the easier D-T) using electromagnetic actuators on magnetized target fusion. Their present goal is to synchronize hammers, as a better method for compression.

    One-shot hammers and chisels could be an intermediate step. From what I experimented at crash-test, reusable shock hardware is a difficulty per se, so such an intermediate step would not be near to the full step. The way I read their documents, they seek reusable hardware.

    Also: one-shot hardware makes experiments much more difficult, lengthy, unreliable. I'd try very hard to go directly to reusable hardware, for ease of experimenting, and to show a more convincing proof.
  13. Aug 7, 2011 #12

    jim hardy

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    mechanical parts timed to like 100nanosecond? i'm not from Missouri but that one i'll have to see.

    old jim
  14. Aug 7, 2011 #13


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    With active, adaptive feedback on hammer timing less than 100ns would not surprise me, though it might prove very expensive.
  15. Aug 17, 2011 #14
    Everyone agrees this is a seriously difficult part of the project! General Fusion does, I do, funds providers do - and want to see the synchronized hammers as the next enabling step.

    Having seen time accuracy around 100µs in crash-test technology, where our actuators had 20ms response time, I imagine General Fusion can achieve the required 1µs with actuators responding in 1ms, for instance the ones I proposed.

    Expensive... In development time, sure. But compare with a pressurized water plant: using existing technology, they sell for 3G€. And worse, compare with the development time of competing fusion devices like Iter or Nif: I would largely prefer to develop the very precise hammers than the other challenges.

    Every new technology needs development, and hard one. We may forget it as it gets common, but for instance piston seals and tyres that last for >100,000km were incredibly difficult to invent. Pneumatic tyres looked impossible before someone convinced himself it was the right way, and eventually found the proper elastomer, reinforcements, seals, fastening...
  16. Sep 23, 2011 #15
    They are using piezo brakes to slow down their pistons so they arrive with the correct timing. I think the jitter they are looking for is around 20us.
  17. Sep 23, 2011 #16


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    I don't know, but that (20us) sounds too long, given that a fission weapon completes detonation in less time, maybe 0.1 us?
  18. Oct 4, 2011 #17
    They are doing MTF, magnetized target fusion, so they probably have some confinement of their plasma. Think ITER with seconds of confinement, vs NIF or a nuke with no confinment but really high power. They are somewhere in the middle.
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