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Thoughts on types of fusion

  1. Jan 9, 2013 #1
    Sonofusion, Cold Fusion, Crossfire, IEC, MC, you name it.

    I'm a young scholar interested in the various kinds of fusion and where they stand in terms of validity, possibility, practicality, etc. I'm mostly curious on what people think of the kinds of fusion out there and what science has shown to work so far.

    My particular interest is in Sonofusion so I suppose I'll start there and ask what kind of progress (or the opposite) has been made and what sort of findings there are on it?
     
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  3. Jan 9, 2013 #2

    Drakkith

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    Bubble Fusion (Sonofusion) doesn't appear to be fusion at all. According to the wiki there is a significant amount of doubt about the quality of the data, and multiple experiments have failed to replicate the results. Although at the same time there appears to be several published papers claiming that their experiments did actually show fusion. However much of this work is highly disputed. I'd say it might need more work, but it looks like a dead end.

    Cold fusion is BS. Plain and simple. People have been doing things for like 20 years and no one has yet to be able to show reliable data that it exists. Most people claiming it does are trying to get funding for their device without letting independent researchers verify that it actually works first or simply doing poor quality experiments. Not a good indicator of a "real" fusion device.

    Crossfire - I don't really know. I don't even know if any devices have even been built.

    IEC - Not going to get anywhere as long as there's a grid that particles can collide with. Period. The Polywell may show promise since the grid is shielded and they use a virtual cathode, but it's too early to say.

    MC - Magnetic Confinement is currently our most likely candidate. The ITER is supposed to break even when it comes online. Let's cross our fingers!
     
    Last edited: Jan 9, 2013
  4. Jan 10, 2013 #3
    @Drakkith Could you please elaborate on the Crossfire fusion because as much as I have read and seen about it , it seems either a scam or the guy just has high hopes on his own idea.
    Well I don' t know maybe you have some deeper papers about him but if that thing would be so great I think there would be huge interest in that from big companies and agencies already.
    The device sounds similar to the "Hirsch Farnsworth fusor" Ok waiting to hear someone elses thoughts.
     
  5. Jan 10, 2013 #4

    Drakkith

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    I know next to nothing about it, sorry.
    My search on google for it lead me to the website for it, but all I saw were design pictures, not an actual built machine, so I assume it hasn't even been built yet. (But I wasn't all that thorough as I was pressed for time)
     
  6. Jan 11, 2013 #5
    Well I was thinking more of the theory of that crossfire fusion , as with Iter it also is just a theory for now until they have the real machine but as we know all machines start with theory and that theory basically tells us is the machine going to work at all and how.
     
  7. Jan 11, 2013 #6

    mfb

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    ITER is based on previous experiments proving the possibility to get significant fusion with magnetic confinement. I don't see a similar demonstration for any other concept except IFC (and maybe myon-catalyzed, but that is not very promising), but that is far away from any reasonable values for a power plant. The polywell concept might be able to get such a demonstration, who knows.
     
    Last edited: Jan 11, 2013
  8. Jan 14, 2013 #7
    There is a great documentary about Fusion by BBC Horizon, especially featuring Sono/Bubble Fusion, including its research efforts and initiatives that have been done/doing, and features Fusion Physicist Rusi Taleyarkhan, a pioneer in Sono/Bubble Fusion, and his struggles with his research and presenting Sono/Bubble Fusion to the Physics Community, which attracted controversy on the subject, and on himself and his career. The documentary also features short accounts of previous Fusion efforts, like the controversy on Cold Fusion and its scientists.

    The BBC Horizon documentary is actually on YouTube. I just watched it myself recently about a couple of months ago, and it's a great informative documentary. BBC Horizon even hired physicists and experts, and did/replicated Taleyarkhan's experiment on Sono/Bubble Fusion themselves. I'd recommend you and the others watch it too. Here's the link on the video.

    I think there's also a separate documentary on Cold Fusion uploaded on Youtube, but I haven't seen it yet.

    Here's more info about Taleyarkhan and Sono/Bubble Fusion:

    http://en.wikipedia.org/wiki/Rusi_Taleyarkhan

    http://en.wikipedia.org/wiki/Bubble_fusion


    I agree that Magnetic Confinement seems to show great promise and possibilities in the future of Fusion, and ITER is on top of this research initiative and project. It uses the "Tokamak" concept. In my opinion, if I may, ITER may be like the LHC in Fusion Research.

    The MC research effort also intersects with Plasma Physics, as MC uses plasmas to be generated and kept confined magnetically, and are "heated" enough to induce Fusion, inside the Tokamak.

    For Rideron, and the others who are interested, you can learn more about Fusion, Magnetic Confinement, Plasmas, and ITER, including their Tokamak machine and their Fusion process, and all their research and project in Fusion, in their website:

    http://www.iter.org/

    ITER - What is fusion?

    ITER - Plasma Heating

    ITER Machine/Tokamak

    ITER - Plasma Confinement


    Note: I would like to apologize if I may have stated any incorrect statements and information in this post, as I humbly admit I am not an expert and still lack complete/working knowledge of Physics in general. Thank you.
     
    Last edited: Jan 14, 2013
  9. Dec 2, 2013 #8
    What would happen if using sonofusion you used a laser to heat the bubble of gas to fusion temp. before it collapsed. Would the rise in temp and pressure from the collapse be enough to cause fusion?
     
  10. Dec 2, 2013 #9

    Drakkith

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    I don't think you can. How are you going to heat a bubble of transparent gas immersed in a liquid?
     
  11. Dec 3, 2013 #10
  12. Dec 3, 2013 #11

    Drakkith

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  13. Dec 3, 2013 #12
    the difference here is that you can heat a pellet by laser in a time period short enough and pulse strenght bigh enough to cause fusion, but the pellet or bubble or whatever you call it cannot me submerged into a thing or medium or some fluid or whatever as that would either block or distort the laser beams that are the fundamental part which runs this process.
     
  14. Jan 10, 2014 #13
    Just for "fun" here is a Tokamak simulation to play around with:

    http://www2.warwick.ac.uk/fac/sci/physics/research/cfsa/research/wpc/tps/tokasim/

    There isn't a whole lot to be learned from it, but it does somewhat demonstrate the difficulties involved with getting a viable output from magnetic confinement.

    And I'll echo about sonofusion not being fusion at all, more like a hoax. MC is really the only game in town at this point. "Cold fusion" isn't "BS" per se, but it is unrealistic as far as we know. There have been experiments with unexplained results and such, meaning there "could" be something to it, but at the same time, nothing consistent. Sonofusion has an even worse track record with nothing close to an explanation of the mechanism involved that makes much sense.

    For fusion, you need pressure and a lot of heat. Your options right now are pretty much magnetic confinement, inertial confinement, a thermonuclear device, or stellar conditions. With viability and feasability from an engineering perspective, magnetic confinement makes the most sense. ICF seems to be just too hard to fine tune enough to be efficient. But I work in fission, not fusion, so I don't have personal experience with any of it.
     
  15. Jan 10, 2014 #14
    I was a nuclear engineering undergraduate at Purdue during the sonofusion "episode." At the time there was a horrific tenure struggle going on. Many of the claims that we levelled at Dr. Taleyarkhan where made by others in the department as part of this struggle. An independent review concluded that Dr. Taleyarkhan only made two ethical violations. He included (with permission) someone's name on a paper when they didn't really contribute to the work, and he claimed he had independent verification of his work when in truth it was his post-doc working in his lab.

    That being said, there is no experimental evidence that sonofusion works. If you look at Dr. Taleyarkhan's original paper he uses a rather large neutron source to cause the bubbles to cavitate. To determine if fusion occurs he measures the neutron beam coming in and out of the sample. If fusion is occurring then there should be more neutrons coming out than going in. Basically this amounts to looking for a specific needle in a haystack of needles. Dr. Taleyarkhan observed more neutrons coming out than going in, and claimed that he observed fusion. But when you do more careful analysis there is no statistically meaningful difference between the two signals. Furthermore the supposed excess neutrons did not exhibit a fusion neutron spectrum.

    There have been attempts to improve the design. Instead of using neutrons to induce cavitation, you can use protons. Thus any neutrons you observe will most likely be from fusion. To my knowledge nobody has observed any such neutrons.


    Nobody has successfully and convincingly demonstrated cold fusion in a laboratory... there is no conclusive experimental evidence that it is physical.

    I think crossfire is an advance IEC design.
    My opinion is that IEC has a lot of potential for applications of fusion not related to power generation. Fusion neutrons could be used to detect explosives (such as land mines or in shipping containers). They can also be used to create medical isotopes. Here due to the compactness of many IEC devices, there is a lot of potential.

    As far as fusion power goes, IEC is decades behind MFE and ICF.

    Finally
    MCF has the most potential (I'm do MCF research so I'm biased). However there are a number of unresolved issues. There biggest is the first wall. The inside of a tokamak (or any burning fusion reactor) is a very harsh environment. We really don't know how materials will behave if exposed to these conditions for significant amounts of time. As a result, we really don't know if any materials exist that can with stand these conditions for prolonged time periods.

    Another issue is size. Current reactor scaling laws suggest that any fusion power plant is going to be huge (1000 MW+). Currently (US) electric utilities are moving away from large generating stations and instead building smaller stations. The reason is mostly economic. It cost billions of dollars to build a large power plant, as a result it takes 30-40 years to pay off the initial involvement and make a profit. Such investments carry a higher risk.
     
  16. Jan 13, 2014 #15
    Wolfman, in the situation you are talking about with a neutron source causing cavitation, and measuring the neutron output, wouldn't you be able to differentiate the neutron energy between those introduced by the source and those from fusion? I don't know by how much off the top of my head, but a neutron from a fusion reaction has a greater kinetic energy than from the next best natural reaction, a fission, and presumably even more so than from any source Taleyarkhan used. Also, wouldn't mass spectrometry be used as well, to find fusion products?
     
  17. Jan 14, 2014 #16
    Yes, if you have the right set-up you can differentiate beam neutrons and fusion neutrons by looking at the neutron energies.As I stated, the supposed excess neutrons did not exhibit a fusion neutron spectrum. I do not know how accurately Dr. Taleyarkhan group was able to measure the spectrum, but IMO this is a pretty strong indication the sonofusion was not going on.

    You could probably use some form of mass spectrometry to look for Helium. However the number of fusion events would still be pretty small, so you'd need a very sensitive system. Also fully ionized Deuterium and Helium have very similar mass to charge ratios. This might further complicate the analysis. I'm not an expert on mass spectrometry so I don't know how feasible this is.

    The easiest solution is to use a ion beam to cause cavitation. Here, if you observe a significant amount of neutrons above background, then you know that they are from fusion.
     
    Last edited: Jan 14, 2014
  18. Jan 16, 2014 #17

    Thanks for your reply. I've used mass spec for determining assay in UF6 samples, but other than that, I am no expert either.
     
  19. Feb 8, 2014 #18
    What about using thousands of lasers in space orbit *all* directed on a tiny fusion target (pellet)?

    Surely laser focusing and power outputs and pulse widths are good enough nowadays to achieve fusion temperatures in a small space?
     
  20. Feb 8, 2014 #19

    mfb

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    It is hard to enough to ignite fusion on earth with this (with football-field sized laser amplification halls), and so far they are some orders of magnitude away from parameters where it gets interesting. You want to build that in space?
     
  21. Feb 10, 2014 #20
    I thought space would offer the advantage of zero gravity and many smaller lasers could be used in space. The present experiment at Jet uses quite an old design of laser.

    I am only guessing but nuclear fusion energy sources are so important I thought it worth a punt.
    Any offers, suggestions? I am sure I could get a pile of funding ...... :)
     
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