Power Density Dilution Due to the Interface of the Isotope with the Transducer
In chapter 4, definitions for various types of dilution factors for a nuclear battery are discussed. The average atomic density of the radioisotope in a nuclear battery cell is described and a relationship between the average atomic density and dilution f
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Power Density Dilution Due to the Interface of the Isotope with the Transducer
Abstract In chapter 4, definitions for various types of dilution factors for a nuclear battery are discussed. The average atomic density of the radioisotope in a nuclear battery cell is described and a relationship between the average atomic density and dilution factor are derived. The dilution factor will impact the minimum scale and the power density of the battery. It is an important parameter that is used in the assessment of nuclear battery designs.
Keywords Radioisotope dilution factor Phase Geometry Scale length matching
The discussion of the interface between the isotope and the transducer begins with the source. In Chap. 1, the maximum power density was calculated for a list of viable nuclear battery isotopes in the compounds which maximizes the atomic density of the radioisotope atoms per cubic centimeter. Depending on the interface, the effective atomic density of the isotope will be diluted compared to the maximum atomic density discussed in Chap. 1. There is no such thing as a perfect interface so any viable interface will dilute the average isotope density. Thus, the power density, which is dependent on the average isotope density, will decrease. The following sections begin by discussing the interface type. An analysis is developed to show how the effective power density is affected by the specifics of the interface design. There is a decrease in the power density which is specific to the design of the interface. The dilution factor can be determined in several ways: • The atomic dilution factor (DFatomic) is calculated if the cell volume is known. First, calculate the number of radioisotope atoms contained in the cell volume (Ncell). Second, assume that the volume is completely filled with a compound that has the maximum possible density of radioisotope atoms (Nmax). The atomic dilution factor is, DFatomic = Ncell/Nmax. • The power density of the radioisotope source in the nuclear battery can be related to the power density available from the compound with the highest known atomic density of the radioisotope (1/BVWmin), Psource = DFatomic/ BVWmin.
© Springer International Publishing Switzerland 2016 M. Prelas et al., Nuclear Batteries and Radioisotopes, Lecture Notes in Energy 56, DOI 10.1007/978-3-319-41724-0_4
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Power Density Dilution Due to the Interface …
• The power dilution factor (DFpower) is defined as the power density of the nuclear battery divided by the power density the compound with the maximum atomic density of radioisotope: • DFpower = (Pout/Vcell)/(1/BVWmin) = Pout*BVWmin/Vcell (where Pout is the power out of the cell and Vcell is the volume of the cell). • The volume dilution factor (DFvolume) is the ratio of the volume of the source material to the total volume of the cell (source plus transducer). • The cell dilution factor (DFcell) is the product of atomic dilution factor and the volume dilution factor: DFcell = DFatomic*DFvolume. The utility of the dilution factors used is as fo
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