The National Solar Thermal Test Facility (NSTTF) includes a 16kW thermal solar furnace facility, composed of a primary heliostat, a secondary spherical concentrator (dish), a 3-axis positioning test table where experiments are placed and an attenuator system. The solar furnace uses a heliostat to track the sun and reflect sunlight through an attenuator system onto the parabolic secondary concentrator. The concentrated sunlight is then reflected onto the test table where test experiments are placed. The focal length of the concentrator is 13.45 ft. with a 6” diameter beam at a maximum concentration of about 6,300 W/cm2. To increase the concentration ratio as high as 650 W/cm2, each respective mirrored facet of the dish is also a curved concentrator. 

Through this arrangement, the focal point is fixed in space, thereby facilitating experimentation.  The power level of the furnace is rapidly adjustable using an attenuator that works like a venetian blind located between the heliostat and the dish. Further flexibility is provided through the 3-axis test platform that can accommodate a variety of sizes and shapes, and even allow for mounting of numerous experimental devices.  This platform utilizes a modular palate system so parallel test systems can be setup and tested concurrently. Power, utilities, and data acquisition is typically attached to the platform through a collection of umbilical cables. 

A wide array of data acquisition and control systems are available including IR pyrometers for temperature measurement and FTIR, GC Mass Spec and RGA systems for gas analysis.  The system is operated from an associated control room.  The furnace has been used for a variety of applications, including measuring physical properties such as thermal expansion, thermal conductivity and diffusivity, specific heat, mechanical properties, and spectral emissivity and absorptivity; simulating thermal effects of nuclear explosions on materials and components; and determining the performance and failure thresholds of high-temperature ceramic and refractory materials. Currently, a variety of solar reactors are also being developed and considered for R&D pertaining to the production of Hydrogen, Ammonia, and cement calcination products, as well as methane reforming.