Direct Conversion from Ionizing Radiation

As demand increases for mobile electronics there is a need to innovate on the power sources. A promising power source is betavoltaics, which generates electricity from the conversion of ionizing radiation from an embedded beta source. Applications include national security benefits for soldiers in the field for extended periods of time to power vital wireless communication systems. Also, betavoltaics could be used as a power source for biomedical implantable devices as well as for simple personal electronics.

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Fig. 1 Betavoltaics competitive advantage for mobile electronics

The basic principle of betavoltaics is similar to the well-known solar cell functionality. The betavoltaics power source is comprised of a beta-emitting material, which will be imbedded in a semiconductor diode junction. The emission of beta-electrons and recoiling nuclei result in electron-hole-pair (EHP) generation. If this EHP is in proximity to a diode junction it will generate a current under the influence of the local electrostatic potential present in the depletion region. The depletion region is a consequence of the p- and n- doped materials forming the junction, which separates the electrons from the holes.1 Consequently, the junction becomes forward biased and current flows through the load. In traditional betavoltaics the power density is low2, but we are investigating promising paths.

[1] Mark Prelas, Charles Weaver, A review of nuclear batteries, Progress in Nuclear Energy, 8 Apr. 2014

[2] Larry Olsen, Cabauy, BJ Elkind, “Betavoltaic Power Sources,” Physics Today 65, No. 12, 35, 2012

[3] Larry Olsen, Review of Betavoltaic Enegry Conversion, NASA N64-11407

[4] Ecoffet, R.. Overview of In-Orbit Radiation Induced Spacecraft Anomalies. IEEE, 60(3), 1791-1815

[5] Geoffrey Landis, Non-Solar Photovoltaics for Small Space Missions, IEEE-NASA, 2011