Extreme Environments Testing

The NSTTF solar furnace uses a heliostat to reflect the suns light off a concentrator dish. This provides a renewable source which is capable of a wide range of high flux test scenarios, thermal model validation tools, and extreme environments. To protect equipment, this dish is in a fixed configuration inside an open-sided building. A heliostat reflects the sun through an attenuator to control the amount of solar flux on target.

Current features and capabilities:

• Peak irradiance of 600 watts per square centimeter
• Maximum temperatures near 3,000 degrees Celsius
• Spot size: 5 centimeters or 3 inches
• 300 psig solar reactor for gas distribution
• 1 torr vacuum solar reactor
• 50,000 frame rate UHF camera system
• FTIR photometrics for onboard spectroscopy
• FLIR camera (−20 degrees Celsius to 2,000 degrees Celsius)
• Up to 32 thermocouples
• 12 channels for voltage and current measurement
• Programmable flux profiles via attenuator

Our extreme testing site includes a one-of-a-kind, high-flux solar simulator with an Automated Sample Handling and Exposure System (ASHES), providing accelerated lifetime aging tests for materials under high-temperature/high-flux conditions. A robotic sample-handling system can be used to move multiple coupons automatically into and out of the concentrated flux sequentially to expose the samples to predetermined temperatures, fluxes, and/or durations.

Current features and capabilities:

• Peak irradiance is approximately 1.1 megawatts per square meter (130 watts per square centimeter).
• Average irradiance of approximately 0.9 megawatts per square meter over a spot size of approximately 1 inch (2.5 centimeters).
• Spot size: 2.5 centimeters.
• 24/7 operation available.
• Programmable Sample System (ASHES).

A new vertical simulator also is in development to reach 500 watts per square centimeter.

Our 36-foot diameter dishes each produce 75 kilowatts of thermal power and peak fluxes up to 1,500 watts per square centimeter. They are individually controlled to track the sun with two-axis control.

The NSTTF Solar Tower has a 0.3 Mach blow-down wind tunnel with a variable frequency drive capable of flow modulation, used to hold test articles during experimentation. The system contains a test panel made of aluminum 6061-T6 alloy, which was developed to hold multiple coupons of refractory sheet low-expansion insulation squares that include two high-speed and slow-speed flux gauges. The wind tunnel utilizes air or nitrogen gas as the working fluid, with the flow progressing from east to west within the test section, maintaining a standoff between the coupon and the wind tunnel inlet. Additionally, the system comprises two sets of large shutters to facilitate flux-pulsed experimentation down to 0.1-second pulse widths. The test section includes quartz glass to allow flow, which can be monitored in real time. The experimental test panel includes RSLE insulation tiles with high-speed flux gauges and a temperature-compensated radiometer to characterize the Gaussian flux profiles incident during each respective test exposure.