ICT2014 Abstracts

Radioisotope Thermoelectric Generators (RTGs) have been successfully demonstrated in several deep space and planetary missions, as well as for terrestrial applications where unattended operation in remote locations is required. NASA’s Radioisotope Power Systems Technology Advancement Project is pursuing the development of more efficient thermoelectric technologies that can increase conversion efficiency and specific power performance by a factor of 2 to 4X over state-of-practice RTGs. The ATEC project is focused on the development, fabrication and testing of power generating segmented couple technologies that incorporate several advanced thermoelectric materials with significantly higher figures of merit. These materials have demonstrated excellent thermal stability and the ability to be processed into relatively robust couple components. To date, conversion efficiencies of up to 15% have been demonstrated for spring-loaded segmented couples fabricated using n-type La_3-xTe₄, p-type Yb₁₄MnSb₁₁ upper temperature segments and skutterudite lower temperature segments and tested in a vacuum environment for up to ~9,000 hours at hot-junction temperatures ranging from 973 K to 1273K and at a cold-junction temperature of 473K. Some of the challenges currently faced in developing high reliability, long life components include the scale-up fabrication of thermoelectric leg segments, processing of thermally stable and mechanically compliant leg metallizations and segment bonds/interfaces.  The current roadmap for the development advanced thermoelectric converters applicable to both radioisotope and fission power systems will be presented as well as progress to date in resolving some of these key challenges