Cold fusion/wip

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Editors: you may comment directly, but your comments will be removed without being archived if anyone feels that they've been addressed in any manner (e.g. if they disagree, if they think it's handled elsewhere). Detailed discussion belongs in Talk:Cold fusion. –M^T

Lead (quick summary of what it is; summary of F/P, rejection, current status (doe report); summary of how it works)

Cold fusion is a theoretical fusion reaction that occurs near room temperature and pressure using relatively simple devices. In nuclear fusion, multiple nuclei are forced to join together to form a heavier nucleus, and during that process, energy is released. The only known method of fusion that releases significant energy is the thermonuclear reaction, where temperatures and pressures are tremendous and must be contained within an as-yet technologically impractical fusion reactor - or be released, as by a fusion bomb.

Cold fusion was brought into popular consciousness by the controversy surrounding the Fleischmann-Pons experiment in March of 1989. A number of other scientists have reported replication of their experimental observation of anomalous heat generation in electrolytic cells, but in a non-predictable way, and most scientists believe that there is no proof of cold fusion in these experiments.

• [1] looks dramatic, is it on the english wiki somewhere? –M^T
  • it is dramatic, but it is amateur science. the experiment is in fact a close reproduction of the glow discharge experiments of Mizuno; however, I can't say that it is particularly well done. see [2] for a photo of the original, and [3] for a lot more; some of those have been contributed in Wikipedia already, and we will probably have no difficulty getting permission for any of them if we contact the authors. ObsidianOrder
    • Dramatic is good. Any pictures that are illustrative or, well, nice looking, should be added. Nobody will (hopefully) argue "but that picture gives the impression that cold fusion is real" or anything like that. –M^T
    • the above MizunoCell.jpg is very clearly not a photograph of the original apparatus as used as it includes a magnetic stir bar at the bottom of the chamber- the original lacked such stirring. --Noren 15:24, 20 October 2006 (UTC)

Contents 1 History 1.1 Early work 1.2 Pons and Fleischmann's experiment 1.2.1 Experimental set-up and observations 2 Process 2.1 Insufficient energy to bring nuclei together 2.2 Lack of expected isotopic products 2.3 Lack of energetic protons, neutrons and gamma rays 2.4 Direct conversion of energy to heat 3 Continuing efforts 3.1 Practical difficulties 3.2 Department of Energy Report

[edit] History

(30%) compare with http://en.wikipedia.org/w/index.php?title=Cold_fusion&oldid=78833288#History_of_cold_fusion

[edit] Early work

The idea that palladium or titanium might catalyze fusion stems from the special ability of these metals to absorb large quantities of hydrogen (including its deuterium isotope), the hope being that deuterium atoms would be close enough together to induce fusion at ordinary temperatures. ...

• This probably belongs under process –M^T
• "close enough" is a very naive (and misleading) description. nobody really thinks the deuterium would be somehow squeezed together. deuterium in metals seems to behave as a quantum-mechanical many body system (based on its bulk properties) and the hope is that the potential energy barrier due to electrostatic repulsion between nuclei may be much lower (or that tunneling will occur with a higher probability) in such a system. ObsidianOrder 08:41, 20 October 2006 (UTC)

... The special ability of palladium to absorb hydrogen was recognized in the nineteenth century. In the late nineteen-twenties, two German scientists, F. Paneth and K. Peters, reported the transformation of hydrogen into helium by spontaneous nuclear catalysis when hydrogen is absorbed by finely divided palladium at room temperature. These authors later acknowledged that the helium they measured was due to background from the air.

In 1927, Swedish scientist J. Tandberg said that he had fused hydrogen into helium in an electrolytic cell with palladium electrodes. On the basis of his work he applied for a Swedish patent for "a method to produce helium and useful reaction energy". After deuterium was discovered in 1932, Tandberg continued his experiments with heavy water. Due to Paneth and Peters' retraction, Tandberg's patent application was eventually denied.

• Is this important to CF? –M^T

[edit] Pons and Fleischmann's experiment

On March 23, 1989, the chemists Stanley Pons and Martin Fleischmann at the University of Utah held a press conference and reported the production of excess heat attributed to a nuclear process. The report was particularly astounding given the simplicity of the equipment: a pair of electrodes connected to a battery and immersed in a jar of heavy water (dideuterium oxide). The press reported on the experiments widely, and it was one of the front-page items on most newspapers around the world. The immense beneficial implications of the Utah experiments, if they were correct, and the ready availability of the required equipment, led scientists around the world to attempt to repeat the experiments within hours of the announcement.

• I find this a particularly amusing description: "connected to a battery and immersed in a jar". Yeah, and you can do it in your garage, just take the battery out of your car and hook it up to some stuff in a canning jar ;) It is dismissive and not NPOV. A better description would be "used electrolysis of heavy water to load a high concentration of deuterium into a palladium electrode inside a precise water-bath calorimeter that could be used to observe the overall heat produced". This brings some of the important stuff right up front, namely: electrolysis is just the method, not the objective; and calorimetry is the main measurement technique. ObsidianOrder 17:16, 20 October 2006 (UTC)

The press conference followed about a year of work of increasing tempo by Pons and Fleischmann, who had been working on their basic experiments since 1984. In 1988 they applied to the US Department of Energy for funding for a larger series of experiments: up to this point they had been running their experiments "out of pocket".

The grant proposal was turned over to several people for peer review, including Steven Jones of Brigham Young University. Jones had worked on muon-catalyzed fusion for some time, and had written an article on the topic entitled Cold Nuclear Fusion that had been published in Scientific American in July 1987. He had since turned his attention to the problem of fusion in high-pressure environments, believing it could explain the fact that the interior temperature of the Earth was hotter than could be explained without nuclear reactions, and by unusually high concentrations of helium-3 around volcanoes that implied some sort of nuclear reaction within. At first he worked with diamond anvils, but had since moved to electrolytic cells similar to those being worked on by Pons and Fleischmann, which he referred to as piezonuclear fusion. In order to characterize the reactions, Jones had spent considerable time designing and building a neutron counter, one able to accurately measure the tiny numbers of neutrons being produced in his experiments.

Both teams were in Utah, and met on several occasions to discuss sharing work and techniques. During this time Pons and Fleischmann described their experiments as generating considerable "excess energy", excess in that it could not be explained by chemical reactions alone. If this were true, their device would have considerable commercial value, and should be protected by patents. Jones was measuring neutron flux instead, and seems to have considered it primarily of scientific interest, not commercial. In order to avoid problems in the future, the teams apparently agreed to simultaneously publish their results, although their accounts of their March 6 meeting differ.

In mid-March both teams were ready to publish, and Fleischmann and Jones were to meet at the airport on the 24th to both hand in their papers at the exact same time. However, Pons and Fleischmann then "jumped the gun", and held their press conference the day before. Jones, apparently furious at being "scooped", faxed in his paper to Nature as soon as he saw the press announcements. Thus the teams both rushed to publish, which has perhaps muddied the field more than any scientific aspects.

Within days scientists around the world had started work on duplications of the experiments. On April 10 a team at Texas A&M University published results of excess heat, and later that day a team at the Georgia Institute of Technology announced neutron production. Both results were widely reported on in the press. Not so well reported was the fact that both teams soon withdrew their results for lack of evidence. For the next six weeks competing claims, counterclaims, and suggested explanations kept the topic on the front pages, and led to what writers have referred to as "fusion confusion."

On April 12 Pons received a standing ovation from about 7000 chemists at the semi-annual meeting of the American Chemical Society. On May 1 a meeting of the American Physical Society held a session on cold fusion that ran past midnight; a string of failed experiments were reported.^[1] The dramatically different reception at the two meetings was attributed to the results of experiments- many scientists had tried and failed to replicate the results in the intervening weeks.

Also in May, the president of the University of Utah, who had already secured a $5 million commitment from his state legislature, asked for $25 million from the federal government to set up a "National Cold Fusion Institute". At the end of May the Energy Research Advisory Board (under a charge of the US Department of Energy) formed a special panel to investigate cold fusion. The scientists in the panel found the evidence for cold fusion to be unconvincing. Nevertheless, the panel was "sympathetic toward modest support for carefully focused and cooperative experiments within the present funding system". [4]

Both critics and those attempting replications were frustrated by what they said was incomplete information released by the University of Utah. With the initial reports suggesting successful duplication of their experiments there was not much public criticism, but a growing body of failed experiments started a "buzz" of their own. Pons and Fleischmann later apparently claimed that there was a "secret" to the experiment, a statement that infuriated the majority of scientists to the point of dismissing the experiment out of hand.

By the end of May much of the media attention had faded. This was due not only to the competing results and counterclaims, but also to the limited attention span of modern media. However, while the research effort also cooled to some degree, projects continued around the world.

[edit] Experimental set-up and observations

In their original set-up, Fleischmann and Pons used a Dewar flask (a double-walled vacuum flask) for the electrolysis, so that heat conduction would be minimal on the side and the bottom of the cell (only 5% of the heat loss in this experiment). The cell flask was then submerged in a bath maintained at constant temperature to eliminate the effect of external heat sources. They used an open cell, thus allowing the gaseous deuterium and oxygen resulting from the electrolysis reaction to leave the cell (with some heat too). It was necessary to replenish the cell with heavy water at regular intervals. The cell was tall and narrow, and the bubbling action of the gas was intended to keep the electrolyte well mixed and of a uniform temperature. Special attention was paid to the purity of the palladium cathode and electrolyte to prevent the build-up of material on its surface, especially after long periods of operation.

• What's an "open cell"? Unless one looks at the diagram, it's not really clear what's going on. Heat from what? what's inside the cell? where's the lattice? how is the reaction started? –M^T
  • open meaning the D2 + O2 gas leaves the cell (into some device that measures its volume, probably). closed would use a catalyst (somewhere in the gas space at the top of the cell) that recombines D2 and O2 back into D2O, so there is no need to add D2O, and no heat is carried away by the escaping gas. lattice - the palladium cathode where the D2 is produced (and absorbed). the cell is filled with D2O+LiOD electrolyte, and also contains the cathode, anode, several thermistors, and the heater. the reaction is started by running current through the cell for several weeks continuously. ObsidianOrder 07:59, 20 October 2006 (UTC)
• This is NPOV. Lack of stirring was one of the specific problems that critics had with the original experiment- for this section to claim that "the bubbling action of the gas kept the electrolyte well mixed and of a uniform temperature." is a claim that was actively argued at the time, presented as fact. Also, the original paper has data from a variety of electrode shapes and sizes- is there a source for the claim that that the cell was tall and narrow for all of them? --Noren 15:19, 20 October 2006 (UTC)
  • For once I agree. It should say "the bubbling action was intended to keep ...". The original P&F cell has been extensively analysed in later papers (Miles, McKubre, ...), and the conclusion is that stirring was not a significant problem. Fluctuating electrolyte levels and heat carried away by gas are probably far more significant sources of inaccuracy. "tall and narrow for all of them" - i believe it was literally the same cell or exact copies. consider that the electrode dimensions are either 1x1x1cm or very small by 1cm or 10cm. so they would all fit in a 2cmx10cm cell. source, i will look. ObsidianOrder 17:03, 20 October 2006 (UTC)
    • The cell was analysed it was concluded that stirring was inadequate. (N. Lewis, et al.) --Noren 20:12, 20 October 2006 (UTC)

The cell was also instrumented with a thermistor to measure the temperature of the electrolyte, and an electrical heater to generate pulses of heat and calibrate the heat loss due to the gas outlet. After calibration, it was possible to compute the heat generated by the reaction.

A constant current was applied to the cell continuously for many weeks, and heavy water was added as necessary. For most of the time, the power input to the cell was equal to the power that went out of the cell within measuring accuracy, and the cell temperature was stable at around 30 °C. But then, at some point in some of the experiments, the temperature rose suddenly to about 50 °C without changes in the input power, for durations of 2 days or more. The generated power was calculated to be about 20 times the input power during the power bursts. Eventually the power bursts in any one cell would no longer occur and the cell was turned off.

[edit] Process

• Theory/Mechanism? (30%, the actual mechanism is described, with copious proper use of the word "hypothetically")

For fusion to occur, Deuterium nuclei (D⁺) must overcome the electrostatic repulsion to come close enough for the strong electrostatic force to take over. This results in the release of energy [what kind of energy?] and various byproducts. In hot fusion, this occurs by...D+D...

• primarily kinetic energy or "recoil". in hot D+D, two ions moving at 0.1MeV collide, fuse, and there is a 1.01 MeV tritium and 3MeV proton (or 0.8MeV 3He and 2.5MeV neutron) ejected. as you can see, those are really fast particles, with more than enough energy to trigger fusion again when they hit something else. depending on the setup and mean free path of each type of particle, you'd expect to see a lot of energetic particles coming out, and particularly neutrons which tend to go through bulk materials quite well. ObsidianOrder 22:56, 19 October 2006 (UTC)

In cold fusion, that much energy for the D+D collision is not available, but there are proposed theoretical explanations for why it may not be necessary because of the metal lattice environment, which are supported by specific experimental results^{[citation needed]}.

In hot fusion T+p, 3He+n, and small quantities of 4He+γ (gamma rays) are produced. These byproducts are recognized indicators ^{[citation needed]} of a fusion reaction. In cold fusion experiments, T and 3He have been observed ^{[citation needed]}, but in very small quantities insufficient to explain the excess energy. Various other byproducts are observed ^{[citation needed]} which leads some researchers to...

• [...] I would generally avoid any statement like "are observed" which implies a well established experimental result, unless it is something that truly has been reproduced many times; I would say "has been observed/reported by several groups" or something like that. ObsidianOrder 22:56, 19 October 2006 (UTC)

4He is observed in a large quantity roughly corresponding to energy, but very little (no?) gamma-rays are seen. Other isotopes with high atomic weights are also produced in small quantities. n are seen in very small quantities as well (and it is disputed whether they are seen at all). There are proposed theoretical explanations supported by experiments for both why the T/3He/4He ratio is different, and why y is not seen. It is also proposed that the main reaction may be D+H or something else instead of D+D, but some of the expected products of those reactions are not observed either. The theoretical explanations are not currently widely accepted outside of the CF field.

Cold fusion experiments indicate ..., [which is why people are developing theories in the first place].

• I'd like the general outline to be "strange behaviour X is occurring. (Some attribute this to experimental error.) Nuclear explanations of the behaviour contradict... . A, B, C are the proposed solutions to this contradiction. [and we emphasize how likely/unlikely each is]" –M^T

• Is kinetic energy the only way to overcome the force?
  • conventionally yes (well, that or muon catalysis, but there would be no muons present here). all cf theories propose different ways to overcome the electrostatic force, since that is one of the fundamental problems of cf. ObsidianOrder 19:45, 19 October 2006 (UTC)

Cold fusion reactions of the type reported by P&F have a number of features which are (impossible according to/incompatible with/counter to) conventional fusion theory:

[edit] Insufficient energy to bring nuclei together

In hot fusion, colliding deuterium nuclei (D⁺) require on the order of 100 keV in kinetic energy to overcome the electrostatic repulsion and come close enough that the strong electrostatic force takes over and results in fusion. That corresponds to an effective temperature of hundreds of millions degrees K. It is unclear how any process can concentrate that much energy in a single deuterium atom in an electochemical cell, or inside the palladium metal lattice, at room temperature, since the average energy of D atoms under those conditions is many orders of magnitude lower.

A more general statement of the theoretical problem is that since the energy and distance scales of chemical (or electrochemical) reactions and nuclear reactions are so disparate, the chemical environment of an atom should have no effect on its nuclear reactions (cite). However, (non-CF/non-controversial) experimental results from the bombardment of deuterium in metal foils with low-energy D+ ions which suggest that the probability of nuclear reactions is strongly enhanced by the metal lattice environment compared to bombarding free deuterium gas (cite Kasagi, J., et al., Strongly Enhanced Li + D Reaction in Pd Observed in Deuteron Bombardment on PdLix with Energies between 30 and 75 keV. J. Phys. Soc. Japan, 1998. 73: p. 608-612.), which (cannot be explained by/contradicts the predictions of) conventional theory that the chemical environment of the deuterium should have no effect.

• lattice? –M^T
  • […]calling it a lattice emphasizes that it has a regular structure which is probably key here, and would have been introduced somewhere in the history section that talks about the odd properties of metal hydrides and PdH specifically which first got people interested in looking at them more closely […] ObsidianOrder 07:30, 19 October 2006 (UTC)

Since excess heat and other anomalous behavior has only been reported in D or H absorbed in a metal lattice, some physicists have tried to formulate (cite Schwinger, J., Cold Fusion, A Brief History of Mine. Trans. Fusion Technol., 1994. 26(4T): p. xiii.) a theory that explains how the metal lattice can serve to effectively lower the electrostatic repulsion or help nuclei tunnel through the potential barrier, in a manner similar to high-temperature superconductivity or other macroscopic quantum effects. Several such theories have been proposed, including resonant tunneling (cite Hagelstein, P.L., Coherent fusion theory. J. Fusion Energy, 1990. 9: p. 451.), ion band states and Bloch condensates (cite Chubb, S.R. and T.A. Chubb, The Role of Hydrogen Ion Band States in Cold Fusion. Trans. Fusion Technol., 1994. 26(4T): p. 414.) (cite Kim, Y.E. and A.L. Zubarev, Nuclear fusion for Bose nuclei confined in ion traps. Fusion Technol., 2000. 37: p. 151.).

• Maybe go with the whole "excess heat, as well as tritium, 4He, alpha particles, and transmutation products", or just mention the anomalous behaviour as a whole (assuming all of the behaviour was mentioned before).–M^T

[edit] Lack of expected isotopic products

In hot fusion the reaction between two deuterium nuclei produces T + p and ³He + n in roughly equal quantities. Although production of low levels of both T and ³He has both been reported in cold fusion (cite Sankaranarayanan, T.K., et al., Investigation of low-level tritium generation in Ni-H2O electrolytic cells. Fusion Technol., 1996. 30: p. 349.) (cite Szpak, S., et al., On the behavior of the Pd/D system: Evidence for tritium production. Fusion Technol., 1998. 33: p. 38.), (cite Kozima, H., et al., Analysis of cold fusion experiments generating excess heat, tritium and helium. J. Electroanal. Chem., 1997. 425: p. 173.) they are not observed in a quantity consistent with the energy output.

It has been proposed that the predominant reaction pathway is D + D -> ⁴He + gamma (cite), which is a very rare reaction pathway in hot D+D fusion (1 in 10⁴). Production of ⁴He has been reported in cold fusion reactions in quantities sufficient to account for a large fraction of the energy output (cite Arata, Y. and Y.C. Zhang, Observation of Anomalous Heat Release and Helium-4 Production from Highly Deuterated Fine Particles. Jpn. J. Appl. Phys. Part 2, 1999. 38: p. L774.) (cite Miles, M. Correlation Of Excess Enthalpy And Helium-4 Production: A Review. in Tenth International Conference on Cold Fusion. 2003. Cambridge, MA), but the corresponding gamma rays are mostly absent. There is no definite theoretical explanation for why a different reaction pathway should predominate in cold fusion, although there is some support for the existence of such an effect from experiments that show a change in reaction branching ratios in deuterated metal foils bombarded with deuterium ions (cite Huke, A., et al., Evidence for a host-material dependence of the n/p branching ratio of low-energy d+d reactions within metallic environments. Eur. Phys. J. A, 2006. 27(s01): p. 187-192.).

• Try to explain "branch probablities" somewhere above.–M^T
  • yep, same as branching ratio, probably the more common term. basically you get the same intermediate nuclear state which then spontaneously decays to different things at different rates. how the chemical environment can affect spontaneous decay of an unstable intermediate nucleus, well... it can't, but it seems to anyway. ObsidianOrder 07:57, 19 October 2006 (UTC)
    • perhaps include this sort of wording in the article itself? –M^T

Other reactions, such as H + D -> T+gamma, and a number of compound reaction paths have also been proposed (cite)

• Give the exact odds of this (and the above) reaction occurring.–M^T
  • that is difficult. conventionally the odds depend on energy, density and effective cross-section, and are vanishingly small for all reactions under the conditions we're talking about. non-conventionally, the reactions are determined primarily by the local environment, and nobody really knows what the effect of that is. maybe we shouldn't say anything about combined probability just on the grounds that it is probably unsourceable (well, it is common knowledge, but if you wanted to find a source that applies it to this particular situation that would be difficult). ObsidianOrder 07:57, 19 October 2006 (UTC)
    • If the reaction is very improbable, or somewhat improbable, or impossible, or... we should say that. –M^T

[edit] Lack of energetic protons, neutrons and gamma rays

If cold fusion was D + D fusion with branching ratios equal to those in hot fusion, half of the reaction would follow the D+D->³He + n pathway, and consequently a high level of neutron radiation corresponding to the excess energy output would be expected (cite). Such neutron radiation would be easily measurable and even enough to be dangerous to anyone in the vicinity (?? rad/second for a person 1m away from a cell with 1mW excess power) (cite). While that level of radiation is not seen, there are reports of very low neutron emissions, starting with the original P&F announcement (cite). The measurement of low levels of neutrons is difficult due to background radiation and so the accutacy of these results is disputed (cite).

• What other reaction branch probabilities could it be following, if not one that produces neutron radiation?
  • unknown. the current favorite is that the reaction is almost entirely D+D->4He, with no more than one in a million along the other branches (and a lot more along the tritium branch than the 3He). that is basically just an educated guess; it contradicts the fewest experimental observations, but it doesn't quite fit everything, see below. ObsidianOrder 08:03, 19 October 2006 (UTC)

The alternative reaction proposed by [researchers?] is D+D->⁴He+gamma. This reaction should produce a high level of 20MeV gamma rays, which would also be very easy to detect. Those are not seen either, although there are reports of low levels of gamma ray emissions (cite). Most other proposed pathways also involve the emission of either gamma rays or neutrons.

• not sure who exactly proposed it first, but Schwinger's article above refers to it and may be one of the early sources. ObsidianOrder 00:40, 20 October 2006 (UTC)

The only type of energetic particle which has been detected at significant levels is alpha particles (⁴He²⁺ nuclei) with energies of ??MeV (cite Szpak, Miley).

[edit] Direct conversion of energy to heat

In hot fusion, a large fraction of the total energy output is carried away as high-energy particles. Since those are mostly absent in reported experimental results, cold fusion would require a highly efficient mechanism to convert fusion energy directly to heat (cite). Several theories of such a mechanism have been proposed, typically by some means of coupling the fusing nuclei to a region of the palladium lattice such as phonons (cite Hagelstein) (similar to the Mossbauer effect, but transferring orders of magnitude more energy). An alternative mechanism for conversion of energy to heat would be through energetic particles with a low mean path such as alpha particles (cite).

[edit] Continuing efforts

(30%, summary of various teams, experiments, etc. Should not be bigger than P/F section)

[edit] Practical difficulties

(preferably not so separated out)

[edit] Department of Energy Report

(somewhat small section on the report)