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Cold fusion
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Cold fusion (sometimes referred to as low energy nuclear reaction (LENR) studies or condensed matter nuclear science) refers to nuclear fusion which occurs without the extremely high temperatures (millions of degrees Celsius) required for thermonuclear fusion – for example, muon-catalysed fusion.
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Encyclopedia
Cold fusion (sometimes referred to as low energy nuclear reaction (LENR) studies or condensed matter nuclear science) refers to nuclear fusion which occurs without the extremely high temperatures (millions of degrees Celsius) required for thermonuclear fusion – for example, muon-catalysed fusion. Cold fusion also can refer to fusion at energies just barely sufficient to overcome the Coulomb barrier, but not hot enough to encourage immediate fission.
Cold fusion made worldwide news headlines in March 1989, when Martin Fleischmann and Stanley Pons held a news conference in which they reported producing nuclear fusion in a tabletop experiment involving electrolysis of heavy water on a palladium (Pd) electrode. They reported anomalous heat production ("excess heat") of a magnitude they asserted would defy explanation except in terms of nuclear processes. They further reported measuring small amounts of nuclear reaction byproducts, including neutrons and tritium. These reports raised hopes of a cheap and abundant source of energy.
Enthusiasm turned to skepticism and scorn as a long series of failed replication attempts were weighed in view of several theoretical reasons cold fusion should not be possible, the discovery of possible sources of experimental error, and finally the discovery that Fleischmann and Pons had not actually detected nuclear reaction byproducts. By late 1989, most scientists considered cold fusion claims dead, and cold fusion subsequently gained a reputation as pathological science. However, some researchers continue to investigate cold fusion and publish their findings at conferences, in books, and scientific journals.
There have been few mainstream reviews of the field since 1990. In 1989, the majority of a review panel organized by the US Department of Energy (DOE) had found that the evidence for the discovery of a new nuclear process was not persuasive. A second DOE review, convened in 2004 to look at new research, reached conclusions that were similar to those of the 1989 panel.
History
Early work
The ability of palladium to absorb hydrogen was recognized as early as the nineteenth century by Thomas Graham. In the late nineteen-twenties, two Austrian born scientists, Friedrich Paneth and Kurt Peters, originally reported the transformation of hydrogen into helium by spontaneous nuclear catalysis when hydrogen was absorbed by finely divided palladium at room temperature. However, the authors later retracted that report, acknowledging that the helium they measured was due to background from the air.
In 1927, Swedish scientist J. Tandberg stated 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.
The term "cold fusion" was coined by E. Paul Palmer of Brigham Young University in 1986 in an investigation of "geo-fusion", or the possible existence of fusion in a planetary core.
Fleischmann-Pons announcement
Martin Fleischmann of the University of Southampton and Stanley Pons of the University of Utah hypothesized that the high compression ratio and mobility of deuterium that could be achieved within palladium metal using electrolysis might result in nuclear fusion. To investigate, they conducted electrolysis experiments using a palladium cathode and heavy water within a calorimeter, an insulated vessel designed to measure process heat. Current was applied continuously for many weeks, with the heavy water being renewed at intervals. Some deuterium was thought to be accumulating within the cathode, but most was allowed to bubble out of the cell, joining oxygen produced at the anode. For most of the time, the power input to the cell was equal to the calculated power leaving the cell within measurement accuracy, and the cell temperature was stable at around 30 °C. But then, at some point (and in some of the experiments), the temperature rose suddenly to about 50 °C without changes in the input power. These high temperature phases would last for two days or more and would repeat several times in any given experiment once they had occurred. The calculated power leaving the cell was significantly higher than the input power during these high temperature phases. Eventually the high temperature phases would no longer occur within a particular cell.
In 1988, Fleischmann and Pons applied to the United States Department of Energy for funding towards a larger series of experiments. Up to this point they had been funding their experiments using a small device built with $100,000 out-of-pocket. The grant proposal was turned over for peer review, and one of the reviewers was Steven E. 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. Fleischmann and Pons and co-workers met with Jones and co-workers on occasion in Utah to share research and techniques. During this time, Fleischmann and Pons described their experiments as generating considerable "excess energy", in the sense that it could not be explained by chemical reactions alone. They felt that such a discovery could bear significant commercial value and would be entitled to patent protection. Jones, however, was measuring neutron flux, which was not of commercial interest. In order to avoid problems in the future, the teams appeared to agree to simultaneously publish their results, although their accounts of their March 6 meeting differ.
In mid-March, both research teams were ready to publish their findings, and Fleischmann and Jones had agreed to meet at an airport on March 24 to send their papers to Nature via FedEx. Fleischmann and Pons, however, broke their apparent agreement, submitting their paper to the Journal of Electroanalytical Chemistry on March 11, and disclosing their work via a press conference on March 23. Jones, upset, faxed in his paper to Nature after the press conference.
Reaction to the announcement
Fleischmann and Pons' announcement drew wide media attention. Scores of laboratories in the United States and abroad attempted to repeat the experiments. A few reported success, many others failure. Even those reporting success had difficulty reproducing Fleischmann and Pons' results. One of the more prominent reports of success came from a group at the Georgia Institute of Technology, which observed neutron production. The Georgia Tech group later retracted their announcement. Another team, headed by Robert Huggins at Stanford University also reported early success, but this too was refuted. For weeks, competing claims, counterclaims and suggested explanations kept what was referred to as "cold fusion" or "fusion confusion" in the news.
In May 1989, the American Physical Society held a session on cold fusion, at which were heard many reports of experiments that failed to produce evidence of cold fusion. At the end of the session, eight of the nine leading speakers stated they considered the initial Fleischmann and Pons' claim dead.
In April 1989, Fleischmann and Pons published a "preliminary note" in the Journal of Electroanalytical Chemistry. This paper notably showed a gamma peak without its corresponding Compton edge, which indicated they had made a mistake in claiming evidence of fusion byproducts. The preliminary note was followed up a year later with a much longer paper that went into details of calorimetry but did not include any nuclear measurements.
In July and November 1989, Nature published papers critical of cold fusion claims.
Nevertheless, Fleischmann and Pons and a number of other researchers who found positive results remained convinced of their findings. In August 1989, the state of Utah invested $4.5 million to create the National Cold Fusion Institute.
The United States Department of Energy organized a special panel to review cold fusion theory and research. The panel issued its report in November 1989, concluding that results as of that date did not present convincing evidence that useful sources of energy would result from phenomena attributed to cold fusion. The panel noted the inconsistency of reports of excess heat and the greater inconsistency of reports of nuclear reaction byproducts. Nuclear fusion of the type postulated would be inconsistent with current understanding and would require the invention of an entirely new nuclear process. The panel was against special funding for cold fusion research, but supported modest funding of "focused experiments within the general funding system."
In the ensuing years, several books came out critical of cold fusion research methods and the conduct of cold fusion researchers.
Further developments
Cold fusion claims were, and still are, considered extraordinary. In view of the theoretical issues alone, most scientists would require extraordinarily conclusive data to be convinced that cold fusion has been discovered. After the fiasco following the Pons and Fleischmann announcement, most scientists became dismissive of new experimental claims.
Nevertheless, there were positive results that kept some researchers interested and got new researchers involved. In September 1990, Fritz Will, Director of the National Cold Fusion Institute, compiled a list 92 groups of researchers from 10 different countries that had reported excess heat, 3H, 4He, neutrons or other nuclear effects.
Fleischmann and Pons relocated their laboratory to France under a grant from the Toyota Motor Corporation. The laboratory, IMRA, was closed in 1998 after spending £12 million on cold fusion work.
Between 1992 and 1997, Japan's Ministry of International Trade and Industry sponsored a "New Hydrogen Energy Program" of US$20 million to research cold fusion. Announcing the end of the program in 1997, Hideo Ikegami stated "We couldn't achieve what was first claimed in terms of cold fusion." He added, "We can't find any reason to propose more money for the coming year or for the future."
In 1994, David Goodstein described cold fusion as "a pariah field, cast out by the scientific establishment. Between cold fusion and respectable science there is virtually no communication at all. Cold fusion papers are almost never published in refereed scientific journals, with the result that those works don't receive the normal critical scrutiny that science requires. On the other hand, because the Cold-Fusioners see themselves as a community under siege, there is little internal criticism. Experiments and theories tend to be accepted at face value, for fear of providing even more fuel for external critics, if anyone outside the group was bothering to listen. In these circumstances, crackpots flourish, making matters worse for those who believe that there is serious science going on here."
In some cases, cold fusion researchers contend that cold fusion research is being suppressed. They complained there was virtually no possibility of obtaining funding for cold fusion research in the United States, and no possibility of getting published. University researchers were unwilling to investigate cold fusion because they would be ridiculed by their colleagues. 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 on the American Physical Society's journal; when it was roundly rejected, in a manner that he considered deeply insulting, he resigned from that body in protest.
To provide a forum for researchers to share their results, the first International Conference on Cold Fusion was held in 1990. The conference, recently renamed the International Conference on Condensed Matter Nuclear Science, is held every 12 to 18 months in various countries around the world. The periodicals Fusion Facts, Cold Fusion Magazine, Infinite Energy Magazine, and New Energy Times were established in the 1990s to cover developments in cold fusion and related new energy sciences. In 2004 The International Society for Condensed Matter Nuclear Science (ISCMNS) was formed "To promote the understanding, development and application of Condensed Matter Nuclear Science for the benefit of the public."
In February 2002, the U.S. Navy revealed that its researchers had been studying cold fusion on the quiet more or less continuously since 1989. Researchers at their Space and Naval Warfare Systems Center in San Diego, California released a two-volume report, entitled "Thermal and nuclear aspects of the Pd/D2O system," with a plea for proper funding.
In 2004, at the request of cold fusion advocates, the DOE organized a second review of the field. Cold fusion researchers presented a review document stating that the observation of excess heat has been reproduced, that it can be reproduced at will under the proper conditions, and that many of the reasons for failure to reproduce it have been discovered.
18 reviewers in total examined the written and oral testimony given by cold fusion researchers. On the question of excess heat, the reviewers' opinions ranged from "evidence of excess heat is compelling" to "there is no convincing evidence that excess power is produced when integrated over the life of an experiment". The report states the reviewers were split approximately evenly on this topic. On the larger question of evidence for nuclear fusion, the report states: On the question of further research, the report reads:
Thirteen papers were presented at the "Cold Fusion" session of the March 2006 American Physical Society (APS) meeting in Baltimore. In 2007, the American Chemical Society's (ACS) held an "invited symposium" on cold fusion and low-energy nuclear reactions. Cold fusion reports have been published in Naturwissenschaften, Japanese Journal of Applied Physics, European Physical Journal A, European Physical Journal C, International Journal of Hydrogen Energy, Journal of Solid State Phenomena, Journal of Electroanalytical Chemistry, and Journal of Fusion Energy. Nevertheless, new reports of excess heat and other cold fusion effects are met with skepticism.
Cold fusion researchers have described possible cold fusion mechanisms, but they have not received mainstream acceptance.
Experimental Details
A cold fusion experiment usually includes:
- a metal, such as palladium or nickel, in bulk, thin films or powder;
- deuterium and/or hydrogen, in the form of water, gas or plasma; and
- an excitation in the form of electricity, magnetism, temperature, pressure, laser beam(s), or of acoustic waves.
Electrolysis cells can be either open cell or closed cell. In open cell systems, the electrolyis products, which are gaseous, are allowed to leave the cell. In closed cell experiments, the products are captured, for example by catalytically recombining the products in a separate part of the experimental system. These experiments generally strive for a steady state condition, with the electrolyte being replaced periodically. There are also "heat after death" experiments, where the evolution of heat is monitored after the electric current is turned off.
Excess heat observations
An excess heat observation is based on an energy balance. Various sources of energy input and output are continuously measured. Under normal condition, the energy input can be matched to the energy output to within experimental error. In experiments such as those run by Fleischmann and Pons, a cell operating steadily at one temperature transitions to operating at a higher temperature with no increase in applied current. At the higher temperature, the energy balance shows an unaccounted term. In the Fleischmann and Pons experiments, the rate of excess heat generation was in the range of 10-20% of total input. The high temperature condition would last for an extended period, making the total excess heat disproportionate to what might be obtained by ordinary chemical reaction of the material contained within the cell at any one time. These high temperature phases did not last indefinitely and did not occur in every experiment, but in those experiments where they did occur, they would usually reoccur several times. Many others have reported similar results.
A 2007 review determined that more than 10 groups world wide reporting measurements of excess heat in 1/3 of their experiments using electrolysis of heavy water in open and/or closed electrochemical cells, or deuterium gas loading onto Pd powders under pressure. Most of the research groups reported occasionally seeing 50-200% excess heat for periods lasting hours or days.
In 1993, Fleischmann reported "heat-after-death" experiments: he observed the continuing generation of excess heat after the electric current supplied to the electrolytic cell was turned off. Similar observations have been reported by others as well.
Reports of nuclear products in association with excess heat
In association with excess heat, researchers have reported observing gamma rays, neutrons, and tritium (3H) production. Although these reports do not measure quantities commensurate with a rate of deuterium fusion that would account for the excess heat, the quantities were reported to be in excess of background levels.
Considerable attention has been given to measuring 4He production. In the report presented to the DOE in 2004, 4He was detected in five out of sixteen cases where electrolytic cells were producing excess heat, although the amounts detected were very close to background levels and contamination by trace amounts of helium normally present in the air is difficult to avoid.
Evidence for nuclear transmutations
There have been reports that small amounts of copper and other metals can appear within Pd electrodes used in cold fusion experiments. Iwamura et al. report transmuting Cs to Pr and Sr to Mo, with the mass number increasing by 8, and the atomic number by 4 in either case.. Cs or Sr was applied to the surface of a Pd complex consisting of a thin Pd layer, alternating CaO and Pd layers, and bulk Pd. Deuterium was diffused through this complex. The surface was analyzed periodically with X-ray photoelectron spectroscopy and at the end of the experiment with glow discharge mass spectrometry. Production of such heavy nuclei is so unexpected from current understanding of nuclear reactions that extraordinary experimental proof will be needed to convince the scientific community of these results.
Non-nuclear explanations for excess heat
The calculation of excess heat in electrochemical cells involves certain assumptions. Errors in these assumptions have been offered as non-nuclear explanations for excess heat.
One assumption made by Fleishmann and Pons is the efficiency of electrolysis is nearly 100%, meaning they assumed nearly all the electricity applied to the cell resulted in electrolysis of water, with negligible resistive heating and substantially all the electrolysis product leaving the cell unchanged. This assumption gives the amount of energy expended converting liquid D2O into gaseous D2 and O2.
The efficiency of electrolysis will be less than one if hydrogen and oxygen recombine to a significant extent within the calorimeter. Several researchers have described potential mechanisms by which this process could occur and thereby account for excess heat in electrolyis experiments.
Another assumption is that heat loss from the calorimeter maintains the same relationship with measured temperature as found when calibrating the calorimeter. This assumption ceases to be accurate if the temperature distribution within the cell becomes significantly altered from the condition under which calibration measurements were made. This can happen, for example, if fluid circulation within the cell becomes significantly altered. Recombination of hydrogen and oxygen within the calorimeter would also alter the heat distribution and invalidate the calibration.
Explanations for cold fusion
Incompatibilities with conventional physics
Postulating cold fusion to explain experimental results raises at least three separate theoretical problems.
1.- The probability of reaction
Because nuclei are all positively charged, they strongly repel one another. Normally, very high energies are required to overcome this repulsion. Extrapolating from known rates at high energies, the rate at room temperature would be 50 orders of magnitude lower than needed to account for the reported excess heat.
2.- The branching ratio
Fusion is a two-step process. In the case of deuterium fusion, the first step is combination to form a high energy intermediary:
- D + D → 4He + 24 MeV
In high energy experiments, this intermediary has been observed to quickly decay through three pathways:
- n + 3He + 3.3 MeV (50%)
- p + 3H + 4.0 MeV (50%)
- 4He + ? + 24 MeV (10-6)
The first two pathways are equally probable, and if one watt of nuclear power were produced, the neutron and tritium production would be easy to measure. Based on attempts to detect neutrons and tritium (3H), the actual rates of the first two pathways are at least five orders of magnitude too low, meaning the branching probabilities given above would have to be completely reversed to strongly favor the third pathway.
3.- Conversion of ?-rays to heat
The ?-rays of the 4He pathway that a nuclear fusion should leave, are not observed. This type of radiation is not stopped by electrode or electrolyte materials, making it necessary to postulate that the 24 MeV excess energy is transferred in the form of heat into the host metal lattice prior to the intermediary's decay. The speed of the decay process together with the inter-atomic spacing in a metallic crystal makes such a transfer inexplicable in terms of conventional understandings of momentum and energy transfer.
Proposed explanations
Several explanations for the experimental results have been proposed. Some groups testing cold fusion concluded that the positive results could be explained by alternative explanations that had nothing to do with cold fusion. Some explain the phenomena as purely electrochemical activity, which is inconsistent with evidence of fusion products in some experiments. According to Heete, "Specific attempts to explain cold fusion as something other than nuclear fusion require similar miracles with equally weak evidence."
Vacuum vs condensed matter
An alternative explanation has been offered treating the space between nuclei as condensed matter instead of vacuum. This way the energy released from the fusion could be effectively transmitted in the proposed time. however, Goodstein states that the reaction times in the lattice are too slow, and the energies involved are much higher than those in cold fusion (KeV versus Mev). Giuliano Preparata has proposed a theory involving the application of quantum electrodynamics to condensed matter.
See also
Bibliography (manuscript)
from SMMIB 2005, 14th International Conference on Surface Modification of Materials by Ion Beams
- (each author writing separately)
- (page numbers refer to a blocked link to an authorized reprint)*
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