A phenomenological study of the Fleischmann-Pons effect

Abstract

This paper reports experiments similar to those in the initial work by Fleischmann and Pons, on electrochemically induced nuclear fusion of deuterium. The experiments have been concerned with measurements of heat evolution and of neutron radiation in and around a cell in which mixtures of deuterium oxide and tritium oxide have been electrolysed using cathodes of palladium. The heat measurements have been made by flow calorimetry. For comparison, analogous measurements have also been made of the heat evolution occuring in similar cells in which common water has been electrolysed under essentially the same conditions. LiOH has been used as electrolyte in all these experiments. The cathodes were made from the bulk metal in a hard-worked condition or after careful annealing to remove structural defects and occluded hydrogen. The data obtained from one experiment with a cathode made of 99.95 % palladium, 3.0 × 3.5 × 55 mm, annealed at 900° C are consistent with the generation of an excess enthalpy of about 1 W during a 30 h period of electrolysis of deuterium oxide at a current density of 84 mA/cm 2. Sporadic flares in the count rates indicated by the neutron detector were observed in this experiment. They correspond to the emission of neutrons from the cell, in brief pulses leading to counts in 15 min intervals from 2 to 8 times (5 to 40 σ) higher than background. Some of the pulses have been shown to have extraneous causes. In the congruent experiments on the electrolysis of common water a heat balance was found that is satisfactory in terms of current theory, i.e., with no excess enthalpy. Two further experiments were made, at current densities of 104 and 115 mA/cm 2 respectively, the first of them with a cathode made of cold-worked palladium and the other with one made of palladium annealed at 800°C. Upward thermal ramps were observed in both of them. They occurred when deuterium oxide was added to the cells to make up the electrolyte to its initial volume. Because of an error in the temperature measurements, these experiments must be taken to be inconclusive as regards the magnitude of the enthalpy excess. It is concluded that the data from these experiments in part support the views advanced by Fleischmann and Pons, regarding anomalies arising in the electrolysis of deuterium oxide at palladium cathodes. It has not been possible to establish any consistent and reproducible pattern in the observations of excess enthalpy and neutron emission. The thermal and the radiation phenomena observed in this work are at a level very close to the limits of resolution of the apparatus used.