Figure 2.2-10. Temperature and Radiation Effects on Solar Array Performance a similar-type cover called Spralon, under contract to JPL. Spralon has been tested at temperature cycles of ± 100°C and results are good. Additional development and testing will have to be performed to show that it can survive the 125°C temperature of SPS. A cross-section view of: (1) a conventional FEP-covered Si cell, (2) the advanced GE/JPL 200-w/kg array, and (3) the Rockwell SPS 1-mil GaAlAs cell is presented in Figure 2.2-12. Conventional solar cell blankets are seen to weigh 109.7 mg/cm^ (0.222 lb/ft2) . The 200-w/kg array is a rollout array with a 3-mil Si cell and weighs 33.8 mg/cm2 (0.0692 Ib/ft2). The 3-mil Si cell is an advanced technology cell; however, the Solarex Company, under contract to JPL (NAS7-100), has fabricated and tested thin Si solar cells. Solarex has delivered more than 500 cells to JPL for evaluation, of which nearly half were 2 to 3 mils thick and 2x2 cm. The cells delivered approximately 60 mw/4 cm2 for an AMO efficiency of 10,5-percent. Based on the GE 200-w/kg array and the Solarex 2- to 3-mil Si cell development programs, it appears that a GaAs solar cell blanket weight has the potential of being developed with a weight of 29.4 mg/cm2 (0.06 lb/ft2) for the post-1985 SPS application. The SPS solar array blanket configuration is shown in Figure 2.2-13. The array consists of three sections taped together to form a width of 25 meters. Kapton supporting tapes 3 mils thick by 5 centimeters wide are fastened to the bottom of the Kapton substrate to serve as support and fastening straps when the blanket is deployed in orbit.
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