On the detection of alpha emission from a low-voltage DC deuterium discharge with palladium electrodes

Abstract

The possibility of nuclear reactions within a low voltage DC deuterium discharge with palladium electrodes is addressed. The solid-state nuclear track detector known as CR-39 was chosen to investigate the emission of energetic charged particles from the electrodes. A partially automated imaging platform and feature classification process was developed to scan the CR-39 surface and detect tracks. Typical discharge parameters were 10 Torr deuterium, 5-7 mm electrode gap distance, 20-40 mA/cm$^2$ current density, and -500 $\pm$ 100 V cathode bias. After discharge treatments to varied ion-cathode fluences, tracks formed in CR-39 which consistently corresponded to 138 $\pm$ 21 keV alpha particles emitted from the palladium electrodes. The track densities for deuterium discharges were often $\sim$100 times above controls with hydrogen and helium. Currently, there are no known mechanisms to accelerate ions to these energies within the apparatus. The production of energetic alpha particles with no source of helium or a means to accelerate the ions to such high energies indicate a nuclear origin. From particle trajectory estimates based on track geometries, it was concluded the reactions originated at the Pd electrodes and not from external sources such as atmospheric radon or cosmic rays.