Some exotic applications for ultrahigh solar fluxes

From the earliest development of these nonimaging devices, when it became apparent that the thermodynamic limit on concentration could be approached, it was appealing to consider how one might practically develop very high levels of concentrated solar flux, in principle approaching even those found on the surface of the sun. However, pursuit of such objectives was deferred while the lower-concentration applications were developed.

Eventually, however, there occurred very rapid progress from the first ultrahigh flux measure­ments conducted on the roof of the high-energy physics building of the University of Chicago in 1988 to the experimental investigation of potential laser pumping and materials processing experi­ments carried out at the National Renewable Energy Laboratory High Flux Solar Furnace. The progression of demonstration experiments is summarized in Table 9.1. A comprehensive descrip­tion of the techniques and history of these measurements is given by Jenkins, O’Gallagher, and Winston (1997).

Some of the potential applications for ultrahigh solar flux concentration include the following:

1. production of exotic materials (e. g., Fullerenes);

2. hydrogen production (direct water splitting);

Table 9.1 Experimental Measurements of Ultra-high Solar Flux Concentration Levels

DATE

LOCATION

secondary

MEASURED FLUX (SUNS)

TOTAL

power

February 1988

Chicago

Lens-oil filled Silver vessel (n = 1.53)

56,000 ± 5000

44 W

March 1989

Chicago

Solid sapphire DTIRC (n = 1.76)

84,000 ± 3500

72 W

July-August

1990

NREL

(Golden, CO)

Water-cooled Reflecting silver CPC—air-filled (n = 1.0)

22,000 ± 1000

3.5 kW

March 1994

NREL

(Golden, CO)

Fused silica (quartz) (n = 1.46) DTIRC with “extractor tip”

50,000 ± 2000

900 W

3. solar pumping of lasers;

4. high-temperature gas turbine solar receivers (Weizmann Institute for Science, Rehovath, Israel);

5. solar thermo-PV converters;

6. solar thermal propulsion in space; and

7. solar processing of materials in a lunar environment (or even in Mars).

The development of these techniques and applications is only one indication of the many fruitful benefits resulting from the concepts of nonimaging optics.

Many of the applications listed in the table for highly concentrated flux have been discussed elsewhere. However, the last two items that appear, application of solar concentrators in space and lunar environment, have not received much attention and may seem a bit bizarre. It is appropriate to consider here some of the unique advantages of nonimaging concentrators for such purposes.

Updated: August 22, 2015 — 2:23 am