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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.
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.
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.pdfI 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.
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.
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.
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...
Quote from: lightarrow on 29/08/2009 18:59:09Ok. 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?
[...]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.
I thought France was building the first prototype that should be producing more energy than it consumes to run it.