[en] Sarnoff has designed an integrated array of thermophotovoltaic (TPV) cells based on the In(Al)GaAsSb/GaSb materials system. These arrays will be used in a system to generate electrical power from a radioisotope heat source that radiates at temperatures from 700 to 1000 C. Two arrays sandwich the slab heat source and will be connected in series to build voltage. Between the arrays and the heat source is a spectral control filter that transmits above-bandgap radiation and reflects below-bandgap radiation. The goal is to generate 5 mW of electrical power at 3 V from a 700 C radiant source. Sarnoff is a leader in antimonide-based TPV cell development. InGaAsSb cells with a bandgap of 0.53 eV have operated at system conversion efficiencies greater than 17%. The system included a front-surface filter, and a 905 C radiation source. The cells were grown via organo-metallic vapor-phase epitaxy. Sarnoff will bring this experience to bear on the proposed project. The authors first describe array and cell architecture. They then present calculated results showing that about 80 mW of power can be obtained from a 700 C radiator. Using a conservative array design, a 5-V output is possible

[en] The mechanism of generation of a nonstationary large-scale high-intensity cyclonic vortex, which does not require for its origination the rotation of the cavity or the presence of a local heat source at the bottom, is described on the basis of experimental results

[en] Examined is a Thermophotovoltaic (TPV) converter using an advanced quaternary III--V cell with an integral filter coupled to isotope (GPHS) and nuclear reactor heat sources. Results presented indicate the merits of TPV conversion for meeting a wide range of space power requirements. The authors find that TPV offers both a reduction in the cost of building the converter for an electric generator driven by a radioisotope or nuclear reactor, as well as appreciable fuel savings. On the basis of cost, they find that isotope powered TPV systems enjoy considerable advantage over solar arrays or interplanetary exploration missions beyond the asteroid belt. For space reactor power systems the analysis indicates that TPV conversion has a mass advantage over thermoelectrics (T/E) for systems below 50 kWe

[en] A process for compacting a granular radioactive material into a sealed solid body for use as a heat source is described. The process is carried out in a hot-cell which is partially evacuated

[en] This letter explains briefly why so-called thermal waves are not truly waves—despite being described mathematically as such—because of their intrinsic diffusive character. This topic should be of interest to those students and teachers dealing with heat transport in the presence of non-stationary harmonic heat sources, photothermal phenomena and techniques, and other related subjects. (letters and comments)

No abstract available

[en] Recently organic flash cycle (OFC) has been proposed which is a vapor power cycle where heat addition occurs with the working fluid remaining in the liquid state. This study proposes a modified OFC with regeneration and carries out thermodynamic performance analysis of the system utilizing low-temperature heat source in the form of sensible energy. Effects of working fluid and flash temperature are systemically investigated on the system performance such as net power production and thermal efficiency. Results show that the net power production has a peak value with respect to the flash temperature but the thermal efficiency increases with the flash temperature. The regenerative system shows higher thermal efficiency compared to the original OFC and improved potential for recovery of low-temperature heat sources.

[en] Mankind will continue to explore the stars through the use of unmanned space craft until the technology and costs are compatible with sending travelers to the outer planets of our solar system and beyond. Unmanned probes of the present and future will be necessary to develop the necessary technologies and obtain information that will make this travel possible. Because of the significant costs incurred, the use of modern manufacturing technologies must be used to lower the investment needed even when shared by international partnerships. For over the last 30 years, radioisotopes have provided the heat from which electrical power is extracted. Electric power for future spacecraft will be provided by either Radioisotope Thermoelectric Generators (RTG), Radioisotopic Thermophotovoltaic systems (RTPV), radioisotope Stirling systems, or a combination of these. All of these systems will be thermally driven by General Purpose Heat Source (GPHS) fueled clad in some configuration. The GPHS clad contains a ²³⁸PuO₂ pellet encapsulated in an iridium alloy container. Historically, the fabrication of the iridium alloy shells has been performed at EG ampersand G Mound and Oak Ridge National Laboratory (ORNL), and girth welding at Westinghouse Savannah River Corporation (WSRC) and Los Alamos National Laboratory (LANL). This paper will describe the use of laser processing for welding, drilling, cutting, and machining with other manufacturing methods to reduce the costs of producing GPHS fueled clad components and complacute eted assemblies. Incorporation of new quality technologies will compliment these manufacturing methods to reduce cost. copyright 1996 American Institute of Physics

[en] An electrical generator having an isotopic heat capsule including a radioactive fuel rod as a primary heat source and thermoelectric modules as converters is described. The biological shield for the capsule is suspended from spiders at each end each consisting of pretensioned rods and defining planes at right angles to each other. The modules are mounted in cups of transition members of a heat rejection fin assembly whose fins extend from both sides of the transition member for effective cooling

[en] The development status of a dynamic space power system for use in satellites in the 1980s and beyond is discussed in this paper. The current Technology Verification Phase is directed to improve system efficiency by component development and to further demonstrate system reliability by endurance testing. 5 refs