Nuclear and Emerging Technologies for Space 2015 (NETS-2015) (2015) 5079.pdf Advanced Radioisotope Thermoelectric Generators (ARTGs) that Leverage Segmented Thermoelectric Technology Bill Otting1, Tom Hammel2, David Woerner 3, and Jean-Pierre Fleurial3 1Aerojet Rocketdyne, 8900 Desoto Avenue, Canoga Park, CA 91304 [email protected] : 818-586-2720 2Teledyne Energy Systems, 10707 Gilroy Road, Hunt Valley, MA 21031 3Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109 Abstract. Advanced thermoelectric materials and couple technologies are being successfully developed at JPL under the NASA sponsored Advanced Thermoelectric Couple (ATEC) program. The new materials have demonstrated a real improvement in power conversion efficiency with thermoelectric couple tests demonstrating more than 15% thermal to electric efficiency across a 1273 K to 473 K T, which is twice that of current thermoelectric materials used in space applications. These advanced materials are the first new and truly promising technology available to radioisotope thermoelectric generator developers in decades. The advanced thermoelectric materials include skutterudite (SKD) materials for operating at temperatures up to about 873K and La3-xTe4/Yb14MnSb11 Zintl materials for extending the operating temperature up to the 1273 K when segmented with the lower temperature SKD materials. The SKD technology is now sufficiently developed that the technology is being transferred to industry (Teledyne Energy Systems) under the Technology Maturation Project. System studies have shown that the SKD couples implemented in the MMRTG generator will result in an enhanced MMRTG (eMMRTG) capable of providing a sizable 25% power boost for the MMRTG. Technology insertion into the existing MMRTG platform provides a low risk path to a very high performing multi-mission generator. The next step will transition the n-type La3-xTe4 and p-type Yb14MnSb11 technologies to production. These materials, when segmented with the SKD materials, produce a high temperature couple suitable for integration with a deep space vacuum generator. Tests of the segmented couples have demonstrated more than 15% thermal to electric efficiency, about twice that of the Cassini style RTG. This high performance generator has the potential to provide power levels and specific power levels much higher than ever before, making missions more capable, cost effective, and potentially even enabling new classes of missions (for example, REP). The new thermoelectric technology, when integrated with existing generator technology, holds the promise of a much shorter generator development cycle with lower development cost/risk. A design study was conducted to understand the first order design tradeoffs between mass, power, and efficiency for a deep space generator implementing the advanced segmented thermoelectric materials. The thermoelectric sizing and layout options were evaluated using the measured thermoelectric material properties. The sizing options were integrated with the generator thermal and heat rejection designs to allow parametric evaluation of the system considering a range of hot and cold junction temperatures. The study evaluated vacuum systems ranging in size from 200 W to 500 W. A modular design approach covering the full range up to 500 W was also evaluated. The study findings include parametric performance results for the various system options, including the system power, mass, efficiency, and specific power. This presentation will summarize the parametric study approach and the parametric results. Keywords: Radioisotope, RTG, ARTG, thermoelectric. .