Abstract
Energy dense power sources are critical to the development of compact, remote sensors for terrestrial and space applications. Nuclear batteries using β--emitting radioisotopes possess energy densities 1000 times greater than chemical batteries. Their power generation is a function of β- flux saturation point relative to the planar (2D) configuration, β- range, and semiconductor converter. An approach to increase power density in a beta-photovoltaic (β-PV) nuclear battery is described. By using volumetric (3D) configuration, the radioisotope, nickel-63 (63Ni) in a chloride solution was integrated in a phosphor film (ZnS:Cu,Al) where the β- energy is converted into optical energy. The optical energy was converted to electrical energy via an indium gallium phosphate (InGaP) photovoltaic (PV) cell, which was optimized for low light illumination and closely matched to radioluminescence (RL) spectrum. With 15 mCi of 63Ni activity, the 3D configuration energy values surpassed 2D configuration results. The highest total power conversion efficiency (ηt) of 3D configuration was 0.289% at 200 µm compared 0.0638% for 2D configuration at 50 µm. The highest electrical power and ηt for the 3D configuration were 3.35 nWe/cm2 at an activity of 30 mCi and 0.289% at an activity of 15 mCi, respectively. By using 3D configuration, the interaction space between the radioisotope source and scintillation material increased, allowing for significant electrical energy output, relative to the 2D configuration. These initial results represent a first step to increase nuclear battery power density from microwatts to milliwatts per 1000 cm3 with the implementation of higher energy β- sources.
