Helium Analysis of Palladium Electrodes after Molten Salt Electrolysis

Abstract

A case of ⁴He enrichment in a spent palladium deuteride electrode is reported. The issue of helium isotope production related to the Fleischmann-Pons effect is still much in debate. In light of this important issue, two palladium samples, used in deuteride- and hydride-conducting molten salt electrolytes, and their corresponding blanks were analyzed for both ³He and ⁴He content. Four specimens from the deuteride sample, which has produced excess heat, showed significant ⁴He signals (enrichment) above the blank background level, while the hydride sample, used as a control with no excess heat measured, exhibited an opposite (depletion) effect. The ³He content remained unchanged, within the limits of the instrument’s sensitivity. The amount of ⁴He detected was not commensurate with the excess heat according to known reaction mechanisms. The interpretation of the results was complicated by a substantial morphology difference among the samples. Because the level of helium content was small in magnitude, the possibility of atmospheric contamination cannot be dismissed completely.