FIGURE 6 EFFICIENCY CHAIN Microwave Power Generation The device which is being considered for converting DC to RF power at microwave frequencies is a cross-field amplifier (Amplitron). The Amplitron uses a platinum metal cathode operating on the principle of secondary emission to achieve a nearly infinite cathode life. The DC voltage required for the Amplitron is 20kV. A Samarium Cobalt magnet provides low specific weight compared to that of conventional permanent magnets utilized in other microwave devices and makes it feasible to use such devices in the SSPS. Radiating surfaces, which will be operating at 300 to 400°F, are designed to reject waste heat, representing about 10% of the input power, to space. Pyrolitic graphite, because of its low density and high emittance, is being considered for the space radiators. A movable magnetic shunt is incorporated in the Amplitron to regulate the output if the input current fluctuates. The movable magnet shunt is the only element subject to wear. Considerations of specific weight, costs, and efficiency at specific frequencies have led to the selection of a frequency near 2.45 GHz, which falls within the
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