Resources
Advanced Stirling Radioisotope Generator (ASRG)

For archival use: An ASRG produces electricity by a triple energy transformation: it first turns the thermal energy from the hot radioisotope fuel into the high-speed kinetic motion of a small piston and its companion displacer.
Development of ASRG flight units was cancelled in late 2013.
Credit
NASA/U.S. Department of Energy