Liquid Droplet Radiator collector development

The radiator can represent the dominant weight penalty on future very high power space systems. A Liquid Droplet Radiator (LDR) has the potential to be significantly lighter than conventional radiators. In the LDR concept, small droplets (about 100..mu..m diameter) of low vapor pressure fluid are sprayed into space, cooled by radiation and collected for recirculation to the heat source. Collection of the multiple droplet stream in a vacuum and zero-gravity requires novel approaches to obtain the near 100% efficiency necessary to minimize fluid loss and prevent spacecraft contamination. All collector ideas including passive, magnetic, centrifugal and electrostatic are being assessed. This paper describes the first seven months of a two-year program. Emphasis was placed on analysis of passive collection and the design of an experimental apparatus for detailed evaluation of droplet collection phenomenon.