electricity, solar cells supply the voltage and current necessary to drive a chain of microwave devices. The microwave energy at 2.45 GHz frequency from many cells is phase- and frequency-locked, then combined and fed to a large microwave antenna for transmission to Earth. A 2.45 GHz microwave frequency is chosen for reason of maximum efficiency. The blackbody radiation also pumps a gas laser medium simultaneously. The laser beam could be sent directly to the ground receivers using appropriate optics, without the need for a conversion process. The potential overall efficiency of this approach, using an intermediate blackbody cavity, is much greater than that of utilizing sunlight directly. An auxiliary power supply may be needed for such an SPS system (e.g. to drive a mechanical pump). However, the cost of the optics and sun-tracking equipment can become an important limiting factor to such an SPS power system. In Section 2 of this paper, a preliminary study is introduced showing the possibility of a solar-electric thermophotovoltaic system. Then, in Section 3, further research on the concept of solar-powered gas lasers, using an electrically heated intermediate blackbody cavity, is described, followed by conclusions and recommendations in Section 4. 2. Solar-Electric Thermophotovoltaic (TPV) Systems 2.1 Introduction Thermophotovoltaic (TPV) devices, potentially efficient in principle, may offer a viable alternative to conventional SPS power systems. In concept, a TPV system concentrates sunlight to heat an intermediate blackbody cavity to a high temperature (2000-2400 K), which re-radiates over a spectrum tending toward longer wavelengths.
RkJQdWJsaXNoZXIy MTU5NjU0Mg==