Effect of Inert Cover Gas on Performance of Radioisotope Stirling Space Power System
This paper describes an updated Orbital design of a radioisotope Stirling power system and its predicted performance at the beginning and end of a six-year mission to the Jovian moon Europa. The design is based on General Purpose Heat Source (GPHS) modules identical to those previously developed and safety-qualified by the Department of Energy (DOE) which were successfully launched to Jupiter and Saturn by the Jet Propulsion Laboratory (JPL). In each generator, the heat produced by the decay of the Pu-238 isotope is converted to electric power by two free-piston Stirling engines and linear alternators developed by Stirling Technology Company (STC), and their rejected waste heat is transported to radiators by heat pipes. The principal difference between the proposed system design and previous Orbital designs (Or et al. 2000) is the thermal insulation between the heat source and the generator's housing. Previous designs had employed multifoil insulation, whereas the design described here employs Min-K-1800 thermal insulation. Such insulation had been successfully used by Teledyne and GE in earlier RTGs (Radioisotope Thermoelectric Generators). Although Min-K is a much poorer insulator than multifoil in vacuum and requires a substantially greater thickness for equivalent performance, it offers compensating advantages. Specifically it makes it possible to adjust the generator's BOM temperatures by filling its interior volume with inert cover gas. This makes it possible to meet the generator's BOM and EOM performance goals without exceeding its allowable temperature at the beginning of the mission.
- Research Organization:
- US Department of Energy, NE-75, Orbital Fairchild
- Sponsoring Organization:
- Orbital Sciences Corporation (OSC)
- DOE Contract Number:
- NE0000115
- OSTI ID:
- 1128538
- Country of Publication:
- United States
- Language:
- English
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