Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: Matthew Burnett on 26/08/2009 10:30:03
-
Matthew Burnett asked the Naked Scientists:
Hello Naked Scientists!
I was contemplating the possibility of cold fusion and wondered whether there are any natural or artificial ways of successfully managing cold fusion in the world or whether the future of cold fusion looks quite poor?
What do you think?
-
The answer depends on the definition of "cold fusion". There is one type of nuclear fusion that can occur at temperatures so low the hydrogen is liquid. See http://en.wikipedia.org/wiki/Muon-catalyzed_fusion
It's not useful because it takes more energy to make the catalyst than you get from the catalyzed fusions (while most catalysts, including this one, are not affected by the reactions they catalyze, in this case the catalyst itself is inherently unstable and simply doesn't last very long).
A more typical and recent definition of "cold fusion" refers to experiments at room temperature, using moderately special electrolysis equipment. The experiments are controversial, and even if nuclear fusion was really happening in them, there is considerable question about how useful it might be. (Not to mention that one substance typically used in the experiments is fairly rare and quite expensive --how could "scaling it up" for global usage be possible?) After 20 years of work, even the True Believers of the subject haven't done the one thing that would convince everyone: generate power reliably.
-
I think (hope?) cold fusion will be achieved at some point. The underlying principle can be seen in welding. A shipyard welder uses white heat to fuse metal. A blacksmith uses red heat and the pressure of his hammer to effect a weld. In cold welding, extreme pressure is used, without any heat see http://www.google.co.uk/search?hl=en&source=hp&q=cold+welding&meta=&rlz=1W1ADBF_en-GB&aq=f&oq= .
Imagine you're trying to cold-weld two steel ball bearings together. If you put on on top of another on a workbench and hit them with a hammer, they're just going to ricochet off all around the inside of your garage. You've got no chance. If however you have a thick tungsten plate with a hole in it, you've got half a chance. You drop your ball bearings into the hole one on top of the other, then you hit them with a piledriver. The question of course, is how to actually achieve this in a reliable fashion that yields more energy than you put in.
I do know a guy who's working on this sort of thing, see http://arxiv.org/find/grp_physics/1/au:+meulenberg/0/1/0/all/0/1 for some interesting papers.
-
I think (hope?) cold fusion will be achieved at some point. The underlying principle can be seen in welding. A shipyard welder uses white heat to fuse metal. A blacksmith uses red heat and the pressure of his hammer to effect a weld. In cold welding, extreme pressure is used, without any heat see http://www.google.co.uk/search?hl=en&source=hp&q=cold+welding&meta=&rlz=1W1ADBF_en-GB&aq=f&oq= .
Imagine you're trying to cold-weld two steel ball bearings together. If you put on on top of another on a workbench and hit them with a hammer, they're just going to ricochet off all around the inside of your garage. You've got no chance. If however you have a thick tungsten plate with a hole in it, you've got half a chance. You drop your ball bearings into the hole one on top of the other, then you hit them with a piledriver. The question of course, is how to actually achieve this in a reliable fashion that yields more energy than you put in.
I do know a guy who's working on this sort of thing, see http://arxiv.org/find/grp_physics/1/au:+meulenberg/0/1/0/all/0/1 for some interesting papers.
Excuse me Farsight, but I haven't grasped the connection between cold welding and cold fusion. I know you are talking about a metaphor, but it doesn't seem to me a valid intuitive reason to believe cold fusion could be achieved one day: in cold welding there is a true contact between atoms, in cold fusion there is not a contact between nuclei.
-
It is a metaphor, lightarrow, but it's valid. Heat is just kinetic energy at the molecular/atomic level, and whilst cold welding is fusing metal rather than nuclei, we're replacing heat with pressure, and the dimensionality of energy is pressure x volume. Take a look at http://en.wikipedia.org/wiki/Nuclear_fusion, and note what it says about the Coulomb barrier. Overcoming that is getting the nuclei to make contact and join together to make a heavier nucleus. Also see http://en.wikipedia.org/wiki/Proton%E2%80%93proton_chain_reaction which talks about the multi-stage proton-proton chain where 4 H + 2 e → He + 2 neutrinos + 6 photons. Two protons fuse together releasing a positron and a neutrino, then a third proton is added releasing a photon, then two trios combine to make a helium atom with two protons left over. The trick is how to manipulate the protons etc like they're like the ball-bearings in pits in the tungsten slab. I'd like to see this getting serious attention instead of the sort of treatment we read about. See http://en.wikipedia.org/wiki/Cold_fusion:
"In some cases, cold fusion researchers contend that cold fusion research is being suppressed.[citation needed] They complained there was virtually no possibility of obtaining funding for cold fusion research in the United States, and no possibility of getting published.[47] University researchers, it has been claimed, were unwilling to investigate cold fusion because they would be ridiculed by their colleagues.[48] In a biography by Jagdish Mehra et al. it is mentioned that to the shock of most physicists, the Nobel Laureate Julian Schwinger declared himself a supporter of cold fusion and tried to publish a paper on it in Physical Review Letters; he was deeply insulted by the manner of its rejection, and was led to resign from that body in protest.[49]"
Note that Julian Schwinger shared a QED Nobel prize with my hero Richard Feynman. By the by, I find these pictures of fused bullets interesting:
http://images.google.co.uk/images?sourceid=navclient&hl=en-GB&rlz=1T4ADBF_en-GBGB240GB240&q=%22bullets%20fused%22&um=1&ie=UTF-8&sa=N&tab=wi
-
Pedantic mode on >>> In fact it is very easy to achieve cold fusion and you can do it in your home for a few thousand pounds of investment and a little skill in making the apparatus. The most expensive bit of the kit is the detector to demonstrate that neutrons are being emitted and therefore fusion is occurring. The problem is not producing fusion but in getting more energy out than you are putting in. >>> Pedantic mode off.
-
If you say so, graham. By the by, I just trawled up this, looks fairly interesting: http://world.std.com/~mica/cft.html
-
It is a metaphor, lightarrow, but it's valid. Heat is just kinetic energy at the molecular/atomic level, and whilst cold welding is fusing metal rather than nuclei, we're replacing heat with pressure, and the dimensionality of energy is pressure x volume.
But the point of cold welding is not using heat, so for analogy, you shouldn't use pressure to overcome the coulomb barrier. Again, what your analogy stands for?
-
Cold welding uses pressure, lightarrow. Heat and pressure are just two forms of energy. More pressure means you need less heat. My analogy is saying cold fusion might be possible if you find a suitable way to substitute heat with pressure.
-
Farsight, here is a link to one of many DIY fusion reactors:
http://www.fusor.net/newbie/files/Ligon-QED-IE.pdf
I am not sure it should really be called a "cold" fusion reactor because it does involve accelerating charged particles to quite high energies, but then I'm not altogether sure that all concepts of "cold" fusion also do not involve fairly high energies also even though (the theory is) that the potential barrier can be lowered in some way so the energies needed are not so high.
-
Excellent graham, thanks. I had a wry smile at this:
They still teach television repair in high school technical education programs, don’t they? But make no mistake, the insides of a television set can kill you in a heartbeat.
I've heard of the Farnsworth fusor before, but forgot all about it. It's rather like those fused bullets I suppose. But I didn't know Robert Bussard (http://en.wikipedia.org/wiki/Robert_W._Bussard) was working on it before he died. One for me to follow up.
-
Cold welding uses pressure, lightarrow. Heat and pressure are just two forms of energy. More pressure means you need less heat. My analogy is saying cold fusion might be possible if you find a suitable way to substitute heat with pressure.
Ok. However heat or pressure is not the only way to overcome the Coulomb barrier, infact the cold-fusion claim is just to be able to exploit the quantum mechanical properties of particles, in particular tunnel effect. Maybe to achieve that we should go in the opposite direction: instead of high temperatures, to use as low as possible...
-
Farsight, here is a link to one of many DIY fusion reactors:
http://www.fusor.net/newbie/files/Ligon-QED-IE.pdf
I am not sure it should really be called a "cold" fusion reactor because it does involve accelerating charged particles to quite high energies, but then I'm not altogether sure that all concepts of "cold" fusion also do not involve fairly high energies also even though (the theory is) that the potential barrier can be lowered in some way so the energies needed are not so high.
If this is a serious device it seems that it would be much more useful for power generation. I wonder why the early diversion to space engines in the pdf document.
-
After a little research (http://www.brian-mcdermott.com/brianfusor2.htm) I find several folks are making these fusion reactors at home and in school labs for a few hundred dollars. The usable output comes directly from the device in the form of direct current at several thousand volts.
While I am not a conspiracy hound, there are some tales of horror among the Google links when you search on Farnsworth Fuser. Many articles contend that the devices were (and are still) methodically suppressed. I can understand why fossil fuel intrests would want to supress it.
-
The link I posted was just a random choice. There is no conspiracy and there is no suppression of information as far as I know. It is just that whilst fusion is not hard to make occur, it is very, very hard to get significant energy out from it.
-
From reading a few links I found with Google, I glean that the main problem with getting power out of the fusion reaction is that ion input cannot continue once the fusion starts. So the fusing ions trapped at the centre of the chamber must gradually fuse out before another cycle can be started. Pumping the next cycle requires more energy than is released by the declining fusion reaction.
However, there was never doubt that nuclear fusion was occurring. This seems more promising than the present cold-fusion or even the multi-billion dollar hot fusion effort. Maybe someone will discover a way for the fusing process to continue as new fuel is pumped into the chamber.
-
Good thread guys.
Vern: there's a lot of competition and vested interest out there. Scientific progress has always been met with resistance from within, they say "science advances one death at a time". The antagonism later gets swept under the carpet.
Graham: I look at http://www.google.co.uk/search?sourceid=navclient&hl=en-GB&ie=UTF-8&rlz=1T4ADBF_en-GBGB240GB240&q=cold+fusion+crackpot and feel unhappy about what I see.
Lightarrow: yes low temperature needs looking at. Vernonnimitz mentioned the Bosenova (http://en.wikipedia.org/wiki/Bosenova) which looks interesting.
-
Vern: there's a lot of competition and vested interest out there. Scientific progress has always been met with resistance from within, they say "science advances one death at a time". The antagonism later gets swept under the carpet.
I think Max Planck held similar views.
Edit: I've spent a couple of hours looking around the net and found this place. (http://www.fusor.net/) It follows a group of quite a few amateur fusors building their own devices. One of them used a Folgers coffee can inside a bell jar. It produced a nice "star in a bottle". The images are copyrighted so I didn't copy it.
-
From reading a few links I found with Google, I glean that the main problem with getting power out of the fusion reaction is that ion input cannot continue once the fusion starts. So the fusing ions trapped at the centre of the chamber must gradually fuse out before another cycle can be started. Pumping the next cycle requires more energy than is released by the declining fusion reaction.
However, there was never doubt that nuclear fusion was occurring.
"There was never doubt" for who, exactly? For the physicists community too? I don't think so...
-
I didn't see any indication that physicists doubted that fusion was occurring in the ion injection process where a charged grid is used to trap high-speed ions in the centre of a vacuum chamber. I got off topic a little in my excitement. Sorry about that.
I know there was and still is a lot of doubt that fusion is happening in the cold fusion experiments.
-
Ok. However heat or pressure is not the only way to overcome the Coulomb barrier, infact the cold-fusion claim is just to be able to exploit the quantum mechanical properties of particles, in particular tunnel effect. Maybe to achieve that we should go in the opposite direction: instead of high temperatures, to use as low as possible...
Such low temps are present at the outside of a spaceship..
So could fusion reactors in the future become part of new propulsion technology for space travel?
-
Ok. However heat or pressure is not the only way to overcome the Coulomb barrier, infact the cold-fusion claim is just to be able to exploit the quantum mechanical properties of particles, in particular tunnel effect. Maybe to achieve that we should go in the opposite direction: instead of high temperatures, to use as low as possible...
Such low temps are present at the outside of a spaceship..
So could fusion reactors in the future become part of new propulsion technology for space travel?
You have found the solution to interstellar journeys... [;)]
-
I know someones who's working on the fusion reactor ITER near Oxford, just a engineer tech guy, but the problems are huge, they've got the plasma stable kinda for milliseconds then they need to do major work on it repair wise any more than that and they've still got no way to get power out of it other than the use the heat it generated to create steam so best hitech stuff we've got connected to a 100+ year old steam engine, laughable really.
They reckon 40 years before they achieve it but they've been saying 40 years for quite some years already.
I think the yanks have a bigger 1 being tested.
-
I say not possible in our life times.
-
I thought France was building the first prototype that should be producing more energy than it consumes to run it.
-
Many country's efforts are concentrated around the Tokamak concept of maintaining a very hot plasma in a magnetic field with a toroidal magnet structure. Heat is gathered from the neutron flux resulting from the fusion by a thick surrounding jacket which then heats steam to drive turbines. So far the results have only been impressive to the people working on it!! They have only produced more energy than was put in for a very short time. The later developments are aimed to improve on this but I would concur with the 40 year time plan. The problems are engineering ones rather than being fundamental, but that is not to belittle them. The international ITER program is based on this I believe.
The main alternative is creating fusion by use of lasers, usually by firing the lasers inwards from a spherical surface to simultaneously heat and compress the fusible gases. This makes for very impressive equipment and, because of the potential rewards from creating a successful fusion reactor, attracts lots of funds. I can't help but be cynical about its prospects for being a commercial success as a means of producing power though.
-
[...]
The main alternative is creating fusion by use of lasers, usually by firing the lasers inwards from a spherical surface to simultaneously heat and compress the fusible gases. This makes for very impressive equipment and, because of the potential rewards from creating a successful fusion reactor, attracts lots of funds. I can't help but be cynical about its prospects for being a commercial success as a means of producing power though.
It probably has greater success as a means to develop powerful lasers for military purposes...
-
And I thought I was cynical :-)
-
Cold fusion does occur but not at energy levels enough to be useful. The trick(catalyst) is to get the nucleii as close together as possible and keep them there for a very long time so the statistics of quantum mechanical tunnelling allow the fusion rection to happen. This is done using a material that will adsorb (incorporate into its structure without chemical combination) small nucleii. Palladium metal is particularly good at doing this and has been used as a way of storing hydrogen.
The existence of fusion is at a very low level is detected by the radiation of the spare neutrons as the duterium fuses to produce He3
Like high temperature superconductivity it may be necessary to design a reduced dimensional atomic structure that manages this very strongly and saturate it with duterium nucleii and there may just be a remote chance that a useful quantity of energy could be generated but catching it could be a problem so your fusion cell should be surrounded by a strong neutron absorber to trap the enegy from the released neutrons and cooling to extract the fusion energy.
If it did work on a modest scale it could easily change the energy budget of the world.
-
I thought France was building the first prototype that should be producing more energy than it consumes to run it.
Ah, yes, after having taken knowledge from the italian researchers who were working on it...