National Aeronautics and Space Administration

Glenn Research Center

Solar Thermal Vacuum Testing

Interior of Tank 6, with 15 foot concentrator and GTD test package

Figure 1: Interior of Tank 6, with 15 foot Concentrator and GTD test package.

The Tank 6 facility shown in Figure 1, is a 68-foot long by 25-foot diameter horizontal vacuum chamber with a liquid nitrogen cryo-wall and a solar simulator. The facility has a 10′ diameter X 10′ long test section, separated from the main chamber with a 10′ gate valve. The solar simulator uses nine 30 kW Xenon arc lamps and was designed to provide no less than 1 Sun (12″ apparent source) on a 15 foot diameter target, 56.5 feet from the source with a subtense angle of less than 1 degree. The vacuum system can provide ambient pressures as low as 0.0000001 torr. The main chamber is pumped with 12 cryopumps, and has an air pumping speed about 1,000,000 l/s, while Xenon pumping speed is about 400,000 l/s. The pumping system was upgraded in early 1999 to provide an “oil-free” pumping system and improve the pumping speed. Liquid nitrogen cryo-wall are divided into three sections and can provide wall temperatures at -320 °F which are capable of > 0.35 MW thermal power loading.

Exterior view of GRC's Tank 6 facility

Figure 2. Exterior view of GRC’s Tank 6 facility

An offset concentrator, as shown in figure 1, consists of seven hexagonal panels with six reflective mirrors per panel is available for solar thermal experiments. The concentrator is 4.75 m wide by 4.55 m tall and is supported on a leaning tripod support structure. A Kendell radiometer is available to make solar flux measurements.