Hydrogen Loading System for Thin Films for Betavoltaics

Abstract

Betavoltaics are direct conversion energy devices that are ideal for low, micropower and long-lasting, uninterruptable applications. Betavoltaics operate similarly to photovoltaics where a radioisotope irradiates beta particles into a semiconductor p-n junction that converts the kinetic energy into electrical energy. Betavoltaics are limited by their power output from the radioiso-tope. The source density can be increased by the selection of solid-state substrates. While solid-state substrates can be selected from simulations, the viability of the substrate to absorb tritium has to evaluated. The development of a hydrogen loading system was performed to evaluate different film types to understand how they perform during the hydrogen/tritium loading process. The hydrogen loading system utilizes the Sievert method, where the initial pressure and volume is constant and pressure drop in the system is used to determine hydrogen uptake of a film substrate. The procedures of the hydrogen loading system are detailed. To test the procedures of the hydrogen loading system, old, palladium films were loaded. Results show uptake of hydrogen by the thin palladium films, as well as cycles of hydrogen absorption and desorption. Hydrogen loading of palladium was compared to a prior result and was shown to have similar results.