Are we close to Nuclear Fusion?

Discussion in 'Physics & Math' started by twr, Jul 13, 2012.

  1. twr Registered Senior Member

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    I've never really been a physics guy, so I don't follow the news in the community, but I was watching a TED debate on the state of nuclear energy. I've never been one for fission, but I'd be completely behind fusion. Have there been any strides in the last 5 years or so? Are we getting close to be able to do it feasibly? Or are we still waiting for someone to have a breakthrough?
     
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  3. prometheus viva voce! Registered Senior Member

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    Take a look at the ITER project : http://en.wikipedia.org/wiki/ITER

    The goal is to produce a plasma that is magnetically contained in a tokamak by 2019, and eventually to have a reaction that produces 10 times the input energy. IMO there are 2 (maybe 3) big problems with this method for generating power: 1) The plasma has to be extremely hot so look out if the magnetic containment fails. 2) because of the Maxwell Boltzmann distribution, only a small number of particles have enough energy to undergo fusion, even at very high energies. In the sun this doesn't matter too much because the sun has a lot of particles - the rate of fusion divided by the number of particles is rather low. For this reason people at ITER are using tritium, an heavy isotope of hydrogen which undergoes fusion more readily than deuterium. Unfortunately that leads to problem 3) Tritium is rare compared to deuterium, making it expensive and tritium is radioactive, making the whole process less desirable.

    Even if we manage to get thermonuclear reactors to work with deuterium, the reactions release neutrons when bombard the walls of the reactor eventually making them radioactive. Sure, it's better than using fission, but it's not the panacea you may have been led to believe it is.
     
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  5. James R Just this guy, you know? Staff Member

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    The standard answer to "how long before we have nuclear fusion power?" is "We'll have it in about 30 years from now."

    That has been the answer since about 1950.
     
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  7. twr Registered Senior Member

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    That gave me a chuckle... I've seen some projects (and yes prometheus, I believe I've heard of ITER before but couldn't remember the name of the project) that seem to be getting close though, and I have confidence that with the boom in communications and computational technology we'll be well on our way in a few decades. To be honest, fusion is the reason I've been avoiding solar stocks for the past few years, but maybe it's time to just put our big old Sol of a galactic fusion generator to work, eh?
     
  8. AlphaNumeric Fully ionized Registered Senior Member

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    We've done various small scale fusion experiments, using things like laser confining or magnetic confining. They produce fusion but currently need more in than they output. You mention computational power. I think the ability to now do extremely fine high accuracy numerical models for the complicated plasma physics within electromagnetic fields, heating by microwaves and undergoing active processes (fusion and decay). Supercomputers are getting powerful enough, cheap enough and available enough (you can lease time and connect via the internet) that these sorts of projects can get access to them. The Livermore labs in the US are always in the top 10 for supercomputers but their nuclear research is in how stockpiles of nuclear weapons age. When you see the complexity of the systems involved you really begin to see the staggering genius of people like Feynman and Shannon to do what they did without computers.
     
  9. RealityCheck Banned Banned

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    Hi TravisW.

    You may be interested in this......

    http://www.focusfusion.org/


    The 'conventional' projects so far only aim to produce heat which can the be converted to elecric current in the usual way. Unlike these conventional projects, the "Focus Device" at the heart of this unconventional approach will give current directly from the 'jet' of ions exiting the focus fusion 'plasmoid' where the fusion actually occurs in a 'self pinch' process/compression that can use safer and less troublesome 'fuel'.

    If you are interested, you can read all about it at the above linked site. Cheers!

    .
     
  10. youreyes amorphous ocean Valued Senior Member

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    How likely is the future world's requirement for Helium-3 will be, based on assessment of ITER tokamak by 2020?
     
  11. Farsight

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  12. kevinalm Registered Senior Member

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    Argueably, The ITER has already failed. That is to say that the ITER and its predicessors have shown that "tokomak" type machines will never produce an economically feasable watt of net power. Basically, the ITER is a hugh, expensive, theoretical plasma physics experiment.

    "We've been studying Tokomaks for (20?) years now, and the one thing we know about them is they're no damn good. They are neat physics though." Or words to that effect.
     
  13. youreyes amorphous ocean Valued Senior Member

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    kevinalm don't be so pathetically foolish, Tokomaks have increased their efficiency at output of power in relation to input of power, yes output is lower still, but thanks to research it has risen steadily over those 20 years. And since fusion is a proven concept on the sun, rest assure we will have it working.
     
  14. AlphaNumeric Fully ionized Registered Senior Member

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    They can produce fusion reactions, though it doesn't last more than a second or so. It's not quite long enough to output more energy than it took to get it started but it's getting close. ITER is aimed at extending this to approximately 15 minute bursts, which would make the whole process energetically viable.
     
  15. kmguru Staff Member

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    We only have one model...that may or may not work very well...there are many other ideas that people need to work at it....
     
  16. quadraphonics Bloodthirsty Barbarian Valued Senior Member

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    I suspect that probably the best way to produce fusion energy is simply to focus on the much easier question of capturing the astronomical quantities of fusion energy that are continuously beamed onto the surface of the Earth, rather than figure out how to replicate, regulate and capture the reaction here.
     
  17. billvon Valued Senior Member

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    Yes, it has. But the gains have been getting smaller of late now that we've picked all the "low hanging fruit" so to speak. It will take a breakthrough to make fusion practical.

    I don't think saying "it works on the sun so it will work here" is all that valid. No physicist is proposing we use the same reaction as the sun uses, for example.
     
  18. Gravage Registered Senior Member

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    It seems to me this will never work...
     
  19. Farsight

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    I wouldn't be surprised if something came out of "cold fusion". It's had a horrible history, so much so that people working in the field now call it LENR, standing for low energy nuclear reactions. The thing to remember is that there's no such thing as "hot" in subatomic physics. A hot material is merely one where the component particles are moving fast. So fast that collisions result in pressure sufficient to overcome the Coulomb barrier. I think a useful analogy here is to be found in welding. An arc welder uses a "blue heat" high temperature and scant pressure. A blacksmith uses red heat and a lot of hammering, which is medium temperature and pressure. Cold welding (see wiki) uses scant heat and a lot of pressure. It's applying pressure that's important, a hot plasma is merely one way of doing it. Maybe there's another way.
     
  20. prometheus viva voce! Registered Senior Member

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    Nice work farsight.
    and in the very next sentence you contradict yourself:
    Lots of people who work on particle physics use the words 'hot' and 'cold' as a shorthand for 'on average the particles are moving quickly,' and 'on average the particles are moving slowly.' Even that is a simplification of 'at some temperature the speed distribution of the particles is given by a Maxwell Boltzmann distribution,' which is not as simple as hot = fast, cold = slow.
     
  21. Farsight

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    I don't contradict myself at all. A "hot" electron is merely a fast-moving electron. Get off your high horse before I knock you off.
     
  22. prometheus viva voce! Registered Senior Member

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    Seriously?! This is too funny!
     

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