A Nuclear-Photon Energy Conversion Study
Report Number: ASD TSR 63-244 Author(s): H. V. Watts, M. D. Oestreich and R. J. Robinson Corporate Author: Armour Research Foundation Date of Publication: 1963-03 Pages: 61 Contract: AF 33(657)8527 Project: 8173 Task: 817301 AD Number: AD0402695 Original AD Number: AD-402 695Contrails does not possess a copy of this report. Click here to offer Contrails a donation of this report
Abstract: A double energy conversion technique was studied for aerospace use as a radioisotope powered 10 watt electrical output power source. In this technique, beta particles from a radioisotope are absorbed by a luminescent material which emits a multiplicity of low energy photons. These photons are then converted to electrical energy by a photovoltaic device. The three components (radioisotope, phosphor, and photovoltaic cell) are discussed individually and then in combination in various geometries of source-phosphor and phosphor-photovoltaic converter. Nuclear radiation effects on the phosphor and photovoltaic materials restrict the choice of the radioisotope to a low energy beta emitter; and temperature effects limit the number of unit power cells which may be stacked in one bundle. These effects are more pronounced in silicon photovoltaic converters than in ZnCdS: Cu type phosphors. A ten watt output power source fabricated with currently available materials (Pm-147, ZnCdS: Cu, and silicon photovoltaic cells) would have an overall energy conversion efficiency of about 0.2 percent and a power per weight ratio of 4 mw/lb. It is estimated that the power per weight could be in creased by a factor of ten to forty if certain ideal materials were available. The rapid decrease in photo voltage and energy conversion efficiency of silicon cells at low illumination intensities causes an appreciable loss in the over all efficiency of such power source.