with radiators having feeders 1.6 times more massive than the panels which they feed. Consequently, radiator configurations were sought which would have lighter feeders. It was recognized that short feeders were dependent upon clustering the radiator panels as closely as possible about the heat source. Figure 4-60 shows both the original and a "halo" configuration which permits a minimum length for the feeders. In both cases the radiator lies in a single plane which is oriented "edge-on" to the predominant meteoroid flow. Fig. 4-60. Original and New Radiator Configurations Figure 4-61 shows the original radiator arrangement with both supply and return feeders attached to the center of the headers. Constant supply and return feeder diameters are used up to the radiator panels where tapering headers are introduced. Fig. 4-61. Original Panel Arrangement Showing Typical Feeder Path to Center-Fed Headers Figure 4-62 shows the new "halo" radiator configuration. This is similar to the original configuration in that the headers are center fed. However, the radiator sections have been clustered closely around the cavity absorber to provide the shortest possible supply and return feeders. Figure 4-63 shows the radiators for one module (4 GWe nominal) of the solar thermionic liquid cooled power satellite system. The radiators are configured in the "halo" design previously Fig. 4-63. Radiator System, Solar Thermionic SPS described. Supply and return feeders are as close to the solar absorber as possible to minimize weight. Headers are secured to structure at the solar absorber end. Expansion of the radiator elements due to temperature changes and creep is provided for by expansion joints to the peripheral structure. The secondary radiators below the absorber support trusses are for cooling the rotary converter assemblies (direct current to alternating current converters). This arrangement of the radiators is typical for other power satellite systems such as the Solar Brayton Cycle. Figure 4-64 shows a typical radiator loop using liquid metal (NaK). This arrangement is for cooling diode collectors in the solar thermionic power satellite. The liquid metal is carried in a multitude of small tubes contacting the diode collectors. The heated metal is pumped through feeders and headers into Fig. 4-62. "Halo" Radiator Configuration
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