Experimental Study of the Direct-Charge Beta Radiation Method for Energy Harvesting

We harvest electrical energy from a radionuclide beta source via the direct-charging method and characterize the parameters that govern the process. The idea is to collect the beta-particles emitted from the source and convert their energy into usable electrical energy without intermediate steps. This is accomplished experimentally with a 63Ni source in a parallel-plates arrangement where the source is the positive electrode and the electrons are collected on the negative electrode. Measurements of the energy harvesting rate are performed with different collector materials, gap sizes, and potential differences between the source and the collector. The resulting efficiencies and the volumetric power densities as functions of these parameters are determined, and the associated energy-loss mechanisms are discussed. The highest measured efficiency of 13.2% was achieved with a carbon collector at a 5-kV potential difference between the electrodes. The maximal volumetric energy density is approximately one-tenth of a common lithium-ion battery.