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37) Coulomb barrier lowering?
Ludwik Kowalski (January 14, 2003)
Department of Mathematical Sciences
Montclair State University, Upper Montclair, NJ, 07043
How can two deuterons fuse without having sufficiently high kinetic energy to overcome repulsion? By the tunneling under the barrier. The theory of than QM effect is well developed and its predictions, for D+D fusion in plasma, agree with experimental data at all kinetic energies above 10,000 eV. But what about even lower energies in solid substances, for example, at 0.05 eV, which is typical? At such energies, according to theoretical calculations, the probability of fusion is about 50 orders of magnitude lower that what would be consistent with the amounts of excess heat. Therefore, argue the critics of cold fusion, what is observed is not ordinary nuclear fusion. Those who believe in reality of cold fusion accept the criticism but claim that Coulomb barrier is somehow lowered in certain chemical environments. But they do not know why this happens.
According to conventional tunneling theory the probabilities of nuclear reactions should not be influenced by changes in chemical arrangements of atomic nuclei in solids. But a study conducted by Kosagi, in 1998, contradicted this expectation, as described by Storms (see my item # 32). Kasagi confirmed that the theoretical predictions of D+D fusion probabilities agree with experimental data at kinetic energies above 10,000 eV. At lower energies, however, the measured probabilities (in the PdO solid) were found to be higher that theoretically predicted. At 2,500 eV, for example, the experimental probabilities (technically expressed in the form of cross sections) are fifty times higher than theoretically predicted. The discrepancy grows very rapidly when kinetic energies become lower.
Unfortunately, no experimental data on D+D fusion probabilities are available below 2,500 eV. Is it reasonable to think that in going from that kinetic energy to 0.05 eV the discrepancy may become much higher, especially when the PdO is replaced by a material able to generate excess heat? Here is how all this was described by Storms (in a review rejected by four journals):
Enhanced Cross Section: The observations imply a higher than expected cross-section for fusion at very low energy. To explore this possibility, Kasagi et al. bombarded various metals and compounds with deuterons of various energies down to 2.5 keV and measured how much enhancement was produced in the reaction D(d,p)T, as shown in Figure 9. Apparently, an increase in cross-section does occur at low energy when the reaction occurs in a solid, in contrast to when the reaction is initiated in a plasma. In addition, enhancement is greater in PdO than in a number of pure elements, thereby showing that the nature of the chemical environment is important. Because the solids were not expected to be nuclear-active under the conditions of the study, the measured cross-sections represent only a lower limit for what might be possible when the correct solid is used. Other studies indicate that the branching ratio between tritium and neutron production might also change at low energy.[164-166] Once these possibilities are acknowledged, the next problem is to propose how the cross-sections might be increased at low energy by the surrounding atoms.
This kind of reasoning can be used to suggest experiments designed to probe the region of lower energies. It should be used to promote new investigations of the tunneling effect at very low kinetic energies. I see nothing unusual in such constructive speculations. Why did the editor of Review of Modern Physics label Storms article as pathological science (see item #33)?
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