Photon Intermediate Direct Energy Conversion Using a ⁹⁰Sr Beta Source

The use of a photon intermediate direct energy conversion (PIDEC) process to develop a proof of concept of a long-lived and efficient nuclear battery powered by a radioactive beta source is discussed. Fundamentally, PIDEC is a means of matching the scale length of the range of radiation to the scale length of the transducer. The device uses a photovoltaic cell and excimer gas-based photon source. In this work, argon was used to produce the excimer photon source (argon excimer at 129 nm) with a pressure range from 7 × 10^-3 to 1.4 × 10⁷ Pa (10^-6 to 2100 psig). The beta source used in this study was a ⁹⁰Sr source that has a daughter, ⁹⁰Y, that then decays to stable ⁹⁰Zr. Intermediate shielding from lead and an argon gas plenum were used to prevent damage to the photovoltaic cell. This battery demonstrated power variations with gas pressure as expected, and no radiation damage to the photovoltaic cell was observed over a period in excess of 150 h. Such a long exposure period demonstrates the desired tolerance of the device to the direct radiation damage that would otherwise be sustained in normal semiconductor-based energy conversion systems.