New optical systems for the solar generation of nanomaterials

Abstract

New strategies for the efficient use of concentrated sunlight to synthesize carbon nanomaterials are described - approaches that offer a potentially far less expensive production facility that is also amenable to being scaled up, in contrast to the conventional costly technologies of laser ablation furnaces and plasma discharge chambers. Our designs employ solar fiber-optic mini-concentrators that completely decouple the collection and remote indoor delivery of solar radiation into a high-temperature nanomaterial reactor. High flux on the target graphite rod is produced by the overlap of low numerical aperture concentrator units - a strategy that also acommodates the sizable gap required between the target inside the reactor and the distal fiber tips on the reactor exterior. The reactor incorporates a nonimaging photon regenerator that traps thermal radiation emitted from the target. This in turn allows a dramatic reduction in solar input relative to earlier solar nanomaterial furnaces. Designs and performance estimates are provided for a systemwith target temperatures in excess of 3000 K, and hence with significant nanomaterial yields.