Session: MNS-01 MEMS/NEMS Power Sources, Sensors and Actuators, and Computing

Paper Number: 66795

Start Time: August 17, 11:10 AM

66795 - Power Density Comparison of Metal and Liquid Radioisotopes 

Radioisotopes are 10³-10⁵ times more energy dense than liquid combustible fuels and chemical storage batteries.  The primary benefit of the increased energy density is operational endurance that comes from multiyear half-life of the decaying radioisotopes, which generate electrical current for the lifetime of the decay.  Compact MEMS sensors providing inertial shock signatures, medical diagnostics, environmental weather and field sensors, along with communications networks for terrestrial studies are among the mission concepts enabled by 20µW-20mW compact radioisotope power sources.  However, the power density from betavoltaic power sources is presently x100 less than that deliverable by chemical battery storage systems.  Maximizing the energy transferred from radioisotope is essential in maximizing electrical power output of this continuous power source.   The purpose of this paper is to compare the energy transfer effectiveness of ⁶³Ni foils to liquid-form ⁶³NiCl₂. Towards this goal, monte-carlo calculations have been performed that compare these radioisotope delivery formats.  Parametric study of specific activity, mass density, and material thickness variations are investigated to understand the trade space in these radioisotope characteristics.  The goal is to increase energy coupling and total energy transfer into the semiconductor energy converters. In planar energy conversion structures, the specific activity has the largest impact to power output.  However in surface etched energy converter structures the radioisotope density and thickness can be matched to energy converter geometry in order to maximize radioisotope fill and electrical power output. The results are compared to experiments.

Presenting Author: Marc Litz Army Research Laboratory

Authors:

Marc Litz Army Research Laboratory
Randy Tompkins Army Research Laboratory
Mohamed Doumbia Army Research Laboratory
Muhammad Khan NSWC