[math-fun] Lockheed Martin Claims Fusion Breakthrough That Could Change World Forever
http://www.forbes.com/sites/williampentland/2014/10/15/lockheed-martin-claim... <http://www.lockheedmartin.com/us/products/compact-fusion.html>Lockheed Martin, the aerospace and defense conglomerate based in Bethesda, Md., is claiming to have made a major breakthrough in <http://www.dvice.com/2013-2-22/lockheeds-skunk-works-promises-fusion-power-four-years>nuclear fusion, which could lead to development of reactors small enough to fit on the back of a truck within a decade. ... --- co-chair http://ocjug.com/
;<curmudgeon hat on> They gave a conference presentation in Feb 2013, and predicted some level of progress by 2017. I'm unsure what inferences to draw from the fact that they are seeking partners: LM is a huge company, and could easily manage to back anything with such unlimited potential. The articles I saw were also quite vague about what the breakthrough actually is. Presumably some definitive experiment has just succeeded, but what is it? It's not beta=1, since the quotes all say "should work" rather than "worked". Given the prior history of this area, they must be pretty confident to be making short term predictions of success. Rich ------ Quoting Ray Tayek <rtayek@ca.rr.com>:
http://www.forbes.com/sites/williampentland/2014/10/15/lockheed-martin-claim...
<http://www.lockheedmartin.com/us/products/compact-fusion.html>Lockheed Martin, the aerospace and defense conglomerate based in Bethesda, Md., is claiming to have made a major breakthrough in <http://www.dvice.com/2013-2-22/lockheeds-skunk-works-promises-fusion-power-four-years>nuclear fusion, which could lead to development of reactors small enough to fit on the back of a truck within a decade. ...
--- co-chair http://ocjug.com/
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I don't know how judge Lockheed-Martin's prospects but this doesn't seem much like cold fusion. It isn't cold and they seem to be claiming an improvement on magnetic-confinement approach. That seems like the way technology moves. Of the little said, one or two things puzzle me. One of the articles says deuterium and tritium are cheap and tritium certainly isn't. Chase's talk talks about using lithium, which is what is done in weapons, and mentions producing tritium from the lithium but it doesn't say how. In bombs that depends on having a lot of neutrons available and I don't see where they would come from in this setup. Whit
The dirty little secret of fusion is that it is dependent on nuclear fission. The fusion reaction is D + T --> He-4 + n. But tritium is not found in nature; it is manufactured by Li-6 + n --> He-4 + T. You could use the neutron produced in the fusion to make the tritium, but free neutrons tend to get lost, and need to be replenished. The neutrons are supplied by nuclear fission in a reactor, which is where tritium is made. So when somebody says fusion will obsolesce nuclear reactors, you know they are lying. Well, there is a loophole. The D + D --> He-4 reaction requires no neutrons, but does require higher operating temperature and pressure. There are also more exotic reactions like Li-7 + p --> 2 He-4 and B-11 + p --> 3 He-4, but these have a higher Coulomb barrier, so require yet higher temperature. One might imagine using D+T fusion as a stepping stone on the way to D+D fusion. Edward Teller has suggested hybrid fission-fusion. Operate fusion, accepting an energy loss, and use the 14 MeV neutrons to fission uranium (and other actinides). Even U-238 is easily fissioned at this energy. Then the fission neutrons are used to make tritium, as well as breeding fission fuel. This is far more likely to succeed than a pure fusion reactor. In addition to tritium, another gift to science from the hydrogen bomb arsenal is helium-3 (the decay product of tritium), much beloved as an exotic fermionic superfluid at millikelvin temperatures. There is also a potential medical application, MRI imaging of air-space in lungs. There are only two gases safe to inhale that have nuclear spin 1/2; they are helium-3 and xenon-129. -- Gene
________________________________ From: Whitfield Diffie <whitfield.diffie@gmail.com> To: math-fun <math-fun@mailman.xmission.com> Sent: Saturday, October 18, 2014 4:52 PM Subject: Re: [math-fun] Lockheed Martin Claims Fusion Breakthrough That Could Change World Forever
I don't know how judge Lockheed-Martin's prospects but this doesn't seem much like cold fusion. It isn't cold and they seem to be claiming an improvement on magnetic-confinement approach. That seems like the way technology moves.
Of the little said, one or two things puzzle me. One of the articles says deuterium and tritium are cheap and tritium certainly isn't. Chase's talk talks about using lithium, which is what is done in weapons, and mentions producing tritium from the lithium but it doesn't say how. In bombs that depends on having a lot of neutrons available and I don't see where they would come from in this setup.
Whit
David Bailey and Jon Borwein have an interesting blog on this issue: http://experimentalmath.info/blog/2014/10/fusion-energy-hope-or-hype/ Also, we can already get energy from fusion, at a cost that is not much different from that of fossil fuels! There is a fusion reactor 93 milllion miles from the earth, with a (free) 5-billion year fuel supply. All we have to do is collect the energy it sends us, using photovoltaic cells and wind generators. Bob Baillie --- Eugene Salamin via math-fun wrote:
The dirty little secret of fusion is that it is dependent on nuclear fission. The fusion reaction is D + T --> He-4 + n. But tritium is not found in nature; it is manufactured by Li-6 + n --> He-4 + T. You could use the neutron produced in the fusion to make the tritium, but free neutrons tend to get lost, and need to be replenished. The neutrons are supplied by nuclear fission in a reactor, which is where tritium is made. So when somebody says fusion will obsolesce nuclear reactors, you know they are lying.
Well, there is a loophole. The D + D --> He-4 reaction requires no neutrons, but does require higher operating temperature and pressure. There are also more exotic reactions like Li-7 + p --> 2 He-4 and B-11 + p --> 3 He-4, but these have a higher Coulomb barrier, so require yet higher temperature. One might imagine using D+T fusion as a stepping stone on the way to D+D fusion.
Edward Teller has suggested hybrid fission-fusion. Operate fusion, accepting an energy loss, and use the 14 MeV neutrons to fission uranium (and other actinides). Even U-238 is easily fissioned at this energy. Then the fission neutrons are used to make tritium, as well as breeding fission fuel. This is far more likely to succeed than a pure fusion reactor.
In addition to tritium, another gift to science from the hydrogen bomb arsenal is helium-3 (the decay product of tritium), much beloved as an exotic fermionic superfluid at millikelvin temperatures. There is also a potential medical application, MRI imaging of air-space in lungs. There are only two gases safe to inhale that have nuclear spin 1/2; they are helium-3 and xenon-129.
-- Gene
________________________________ From: Whitfield Diffie <whitfield.diffie@gmail.com> To: math-fun <math-fun@mailman.xmission.com> Sent: Saturday, October 18, 2014 4:52 PM Subject: Re: [math-fun] Lockheed Martin Claims Fusion Breakthrough That Could Change World Forever
I don't know how judge Lockheed-Martin's prospects but this doesn't seem much like cold fusion. It isn't cold and they seem to be claiming an improvement on magnetic-confinement approach. That seems like the way technology moves.
Of the little said, one or two things puzzle me. One of the articles says deuterium and tritium are cheap and tritium certainly isn't. Chase's talk talks about using lithium, which is what is done in weapons, and mentions producing tritium from the lithium but it doesn't say how. In bombs that depends on having a lot of neutrons available and I don't see where they would come from in this setup.
Whit
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* Robert Baillie <rjbaillie@frii.com> [Oct 19. 2014 19:04]:
David Bailey and Jon Borwein have an interesting blog on this issue: http://experimentalmath.info/blog/2014/10/fusion-energy-hope-or-hype/
Also, we can already get energy from fusion, at a cost that is not much different from that of fossil fuels! There is a fusion reactor 93 milllion miles from the earth, with a (free) 5-billion year fuel supply. All we have to do is collect the energy it sends us, using photovoltaic cells and wind generators.
Hey, I have got the copyright on this on math-fun. One dollar please! Best regards, jj
Bob Baillie
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Fun problem from the new book Inside Interesting Integrals: given a circle, pick three points inside it at random (uniformly). These points define another circle. What is the probability that this circle lies entirely inside the original circle? The theoretical answer is 2pi/15 = 0.418879... But Monte-Carlo simulations strongly suggest that the answer is in fact exactly 2/5. So what gives? Original derivation from A Treatise on the Integral Calculus, Edwards, 1922: https://dl.dropboxusercontent.com/u/70818776/edwards-circles.png My MC source code (Nahin, author of Inside Interesting Integrals, also did MC simulations, which give the same result, and pointed out the discrepancy): https://dl.dropboxusercontent.com/u/70818776/interesting-circles.cpp I should say that a bunch of us debated this over Facebook for a while, and the problem was eventually resolved to my satisfaction by Zachary Abel. But it's still something you may enjoy puzzling over. Bob Hearn
On 19/10/2014 04:47, Bob Hearn wrote:
Fun problem from the new book Inside Interesting Integrals: given a circle, pick three points inside it at random (uniformly). These points define another circle. What is the probability that this circle lies entirely inside the original circle? The theoretical answer is 2pi/15 = 0.418879... But Monte-Carlo simulations strongly suggest that the answer is in fact exactly 2/5. So what gives?
Original derivation from A Treatise on the Integral Calculus, Edwards, 1922:
https://dl.dropboxusercontent.com/u/70818776/edwards-circles.png
My MC source code (Nahin, author of Inside Interesting Integrals, also did MC simulations, which give the same result, and pointed out the discrepancy):
https://dl.dropboxusercontent.com/u/70818776/interesting-circles.cpp
Initial pure-prejudice reaction: A mathematical error is more likely than a numerical error of such magnitude. Two independent MC runs are unlikely to have the same mathematical error in them. So my guess is that Edwards made a mistake. Also, I kinda wouldn't expect a factor of pi in the probability. Initial slightly-more-than-prejudice reaction on looking at Edwards's alleged proof: That looks really fishy to me; it wouldn't surprise me if what he's actually computed has (e.g.) the probabilities implicitly weighted in proportion to the radius of the "inner" circle or something like that. So my money is on the simulations' answer being correct. (Either because the exact probability is 2/5, or because it's something else close to 2/5 and not so close to 2pi/15.) (But I haven't looked at the MC code, nor have I thought carefully enough about Edwards's proof to be sure it can't be made rigorous without changing the answer.) -- g
participants (8)
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Bob Hearn -
Eugene Salamin -
Gareth McCaughan -
Joerg Arndt -
Ray Tayek -
rcs＠xmission.com -
Robert Baillie -
Whitfield Diffie