Figure IV-9.- Solar cell blanket. 2. Power Distribution A nominal operating voltage of 40 kV was selected for this study. Other studies have used 20 kV to match the operating voltage of the amplitron microwave generator. However, the higher voltage offers a significant weight advantage and can presumably be used with amplitrons in series pairs. In addition, 40 kV is compatible with the klystron, an alternative to the amplitron. Still higher voltages could be used, but arcing and voltage breakdown could require more insulation weight. Pure aluminum was used as the conducting material in preference to copper or silver on the basis of resistivity and density. If structural properties are required, 6061 aluminum is still preferable to copper or silver. Superconductors were not seriously considered because of the weight and complexity of the refrigeration system. The ideal shape of a conductor is a thin, flat sheet for optimum heat dissipation. Thus, the aluminized solar array concentrator is an interesting candidate. A thickness of 12.5 mm (0.5 mil) should provide sufficient cross-sectional area. Positive and negative conductors can be separated by the width of the cell blanket over most of the array, but insulation would be required in some locations. Magnetic effects between conductors have not been analyzed. It is possible that the resulting forces will distort the surface of the concentrators, causing uneven illumination of the cell blanket. Because of the high current levels (220 000 A at the rotary joint), switching should not be done within the array distribution system. On-off switching can occur at the solar cell blanket interface with the distribution system. It is assumed that regulation to limit overvoltage will be done within this cell blanket.
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