Study of deuterium charging in palladium by the electrolysis of heavy water

The production of heat excess (HE) in electrolytic cells with heavy water and palladium cathodes is, in Cold Fusion, the experiment that has had more confirmations, even though still doubts are cast on its nuclear origin. Furthermore, the correlation of HE with some features of the experiment seems to be well established, the most convincing of which is a threshold in the D/Pd ratio. What is yet not quite clear is how to obtain a high D/Pd ratio, since this feature seems to depend both on the material and on the procedures adopted for the electrolysis. In this paper we will propose a novel approach to this problem, which permits to correlate HE with other features of the experiment. In particular, we try to study the transport of matter across the palladium lattice during the electrolysis. A model, proposed by two of us (ADN e VV), and presented in this Conference, helps to interpret the experimental results, and gives interesting hints for future research. As far as the nuclear nature of the HE is concerned, it seems today clear that the only serious way to address this problem consists in performing experiments in which the presence of 'nuclear ashes' is searched, 4He nuclei being the most likely to be found. Such an experiment has been performed once, and needs confirmation. We plan to perform an experiment in which the production of 4He nuclei can be detected in the gases evolving from the electrolytic cell, in coincidence with the production of HE. A cryogenic system able to separate 4He from other gases, including D2, has been designed, and preliminary data on its behaviour are presented. (author)