LASERS IN SPACE.

The large central power station beaming power to remote users is one of the most extensively studied potential uses of the high-power space laser. Three power station concepts - an electric discharge laser powered by photovoltaic array, a solar-pumped laser, and a nuclear-pumped-laser as an integral part of a gas core reactor (each producing a beam power of 100 Mw) - have been suggested. All three designs are large and would probably involve comparable levels of difficulty in terms of deployment and construction in space. The photovoltaic electric-discharge laser (EDL) is dominated by a solar cell array, the solar-pumped laser by a solar reflector, and the nuclear-pumped laser by the radiator array needed to dissipate excess heat produced by the reactor. Of the three systems, the technology for the photovoltaic EDL is by far the most advanced and such a system could probably be built, although it would be relatively expensive. The nuclear-pumped laser has also received considerable study and a fairly strong technological base exists for both the laser and the gas core reactor as individual systems. However, what has not yet been demonstrated is the integration of the reactor and laser into a single unit. The solar-pumped laser idea is the newest of the three concepts and although both a solar-pumped laser and a blackbody-pumped gas laser have been demonstrated in the laboratory the technology is still at a very early stage of development.