A Computational Method for Assessment of the Charge Collection Efficiency in Self-Reciprocating Radioisotope Power Generators

Abstract

According to static model balancing, the electrostatic and mechanical forces from an equivalent circuit one can have an analytical solution useful for characterization of a self-reciprocating radioisotope-fueled micropower generator. Charge collection efficiency (CCE) , an empirical coefficient describing the portion of the total emitted current that gets collected by the cantilever, is an important parameter to gauge the usefulness of the cantilever. In this paper, based on MCNP Monte Carlo calculations, an applicable computational method has been proposed for assessment of the CCE in self-reciprocating radioisotope-powered cantilevers. Validity of the proposed method has been confirmed via comparison of the simulation results on CCE with the experimental value for this parameter, namely, 13.59% and 14.2%, respectively, in a previously demonstrated prototype cantilever device. The relative difference between computational and experimental results is within 4%, which confirms that the order of magnitude of the results is very close. Furthermore, suggestions have been proposed and investigated for the enhancement of the CCE in self-reciprocating radioisotope-fueled power generators. Effect of cantilever geometry and material on CCE has been investigated for some material and geometry specifications. The obtained results are indicative of the fact that this method can be used to investigate optimized design parameters in order to improve the total efficiency of the device.