User talk:Kevin Baas/workspace/cold fusion refactoring

Unusual energy phenomena
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. In other experiments, however, no excess heat was discovered, and, in fact, even the heat from successful experiments was unreliable and could not be replicated independently. If higher temperatures were real, and not experimental artifact, the energy balance would show an unaccounted term. In the Fleischmann and Pons experiments, the rate of inferred 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 appear to be disproportionate to what might be obtained by ordinary chemical reaction of the material contained within the cell at any one time, though this could not be reliably replicated. Many others have reported similar results.

A 2007 review determined that more than 10 groups worldwide reported 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.

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 Fleischmann and Pons is that the efficiency of electrolysis is nearly 100%, meaning 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 electrolysis 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.

Missing gamma rays
The γ-rays of the 4He pathway are not observed. It has been proposed that the 24 MeV excess energy is transferred in the form of heat into the host metal lattice prior to the intermediary's decay. However, 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.

Unusual matter phenomena
Deuteron fusion is a two-step process, in which an unstable high energy intermediary is formed:
 * D + D → 4He* + 24 MeV

High energy experiments have observed only three decay pathways for this excited-state nucleus, with the branching ratio showing the probability that any given intermediate will follow a particular pathway. The products formed via these decay pathways are:
 * n + 3He + 3.3 MeV (50%)
 * p + 3H + 4.0 MeV (50%)
 * 4He + γ + 24 MeV (10&minus;6)

Only about one in one million of the intermediaries decay along the third pathway, making its products comparatively rare when compared to the other paths. If one watt of nuclear power were produced from deuteron fusion consistent with known branching ratios, the resulting neutron and tritium (3H) production would be easily measured. Some researchers reported detecting 4He but without the expected neutron or tritium production; such a result would require branching ratios strongly favouring the third pathway, with the actual rates of the first two pathways lower by at least five orders of magnitude than observations from other experiments, directly contradicting mainstream-accepted branching probabilities. Those reports of 4He production did not include detection of gamma rays, which would require the third pathway to have been changed somehow so that gamma rays are no longer emitted.

Lack of neutron radiation
Fleischmann and Pons reported a neutron flux of 4,000 neutrons per second, as well as tritium, while the classical branching ratio for previously known fusion reactions that produce tritium would predict, with 1 watt of power, the production of 1012 neutrons per second, levels that would have been fatal to the researchers.

In 2009, Mosier-Boss et al. reported what they called the first scientific report of highly energetic neutrons, using CR-39 plastic radiation detectors, although some scientists say that the results will need a quantitative analysis in order to be accepted by the physics community.

Helium ash
Considerable attention has been given to measuring 4He production. In 1999 Schaffer says that the levels detected were very near to background levels, that there is the possibility of contamination by trace amounts of helium which are normally present in the air, and that the lack of detection of Gamma radiation led most of the scientific community to regard the presence of 4He as the result of experimental error. 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. The reviewers' opinion was divided on the evidence for 4He; some points cited were that the amounts detected were above background levels but very close to them, that it could be caused by contamination from air, and there were serious concerns about the assumptions made in the theoretical framework that tried to account for the lack of gamma rays.

Nuclear transmutations
In 1999 several heavy elements had been detected by other researchers, especially Tadahiko Mizuno in Japan, although the presence of these elements was so unexpected from the current understanding of these reactions that Schaffer said that it would require extraordinary evidence before the scientific community accepted it. The report presented to the DOE in 2004 indicated that deuterium loaded foils could be used to detect fusion reaction products and, although the reviewers found the evidence presented to them as inconclusive, they indicated that those experiments didn't use state of the art techniques and it was a line of work that could give conclusive results on the matter.

--

Why cold fusion is unexpected / not predicted
Cold fusion researchers have described possible cold fusion mechanisms (e.g., electron shielding of the nuclear Coulomb barrier), but they have not received mainstream acceptance. In 2002, Gregory Neil Derry described them as ad hoc explanations that didn't coherently explain the experimental results.

Many groups trying to replicate Fleischmann and Pons' results have reported alternative explanations for their original positive results, like problems in the neutron detector in the case of Georgia Tech or bad wiring in the thermometers at Texas A&amp;M. These reports, combined with negative results from some famous laboratories, led most scientists to conclude that no positive result should be attributed to cold fusion, at least not on a significant scale.

There are at least three reasons that fusion is an unlikely explanation for the experimental results described above.

Probability of reaction
Because nuclei are all positively charged, they strongly repel one another. Normally, in the absence of a catalyst such as a muon, very high kinetic energies are required to overcome this repulsion. Extrapolating from known rates at high energies down to energies available in cold fusion experiments, the rate for uncatalyzed fusion at room-temperature energy would be 50 orders of magnitude lower than needed to account for the reported excess heat.

Since the 1920s, it has been known that hydrogen and its isotopes can dissolve in certain solids at high densities so that their separation can be relatively small, and that electron charge inside metals can partially cancel the repulsion between nuclei. These facts suggest the possibility of higher cold fusion rates than those expected from a simple application of Coulomb's law. However, modern theoretical calculations show that the effects should be too small to cause significant fusion rates. Supporters of cold fusion pointed to experiments where bombarding metals with deuteron beams seems to increase reaction rates, and suggested to the DOE commission in 2004 that electron screening could be one explanation for this enhanced reaction rate.