Initial Development of a High-Power Solid-State Solar Simulator
Our team has developed and tested a solid-state solar simulating lamp for use with space simulation vacuum chambers. Unlike traditional lamps, our system uses solid-state light-emitting diodes (LEDs) to generate the light. The emission wavelengths of the LEDs can be selected and controlled so that their combined output better approximates the profile of the solar spectrum. Though our system can accommodate visual or infrared LEDs, we focused our efforts on generating ultraviolet (UV) light in the 265-400 nanometer (nm) range. Compared to deuterium lamps, the LEDs are advantageous because they can be selected and controlled such that the output profile of the lamp better approximates the irradiance of the sun. Deuterium lamps are most intense at 200 nm with their intensity decreasing by more than 90% as the spectrum approaches 400 nm. Light from the sun is of relatively low intensity in the 200-250 nm range, but its intensity increases by more than 2000% from 250 nm to 400 nm. The modular design of our lamp (Figure 1) allows it to individually control the current to each of 80 strings of LEDs, totaling to 904 individual UV LEDs in a compact, circular pattern designed to shine through an 11.5-inch-diameter chamber window. The light from each LED is collimated using a 6-millimeter-diameter silica ball lens, and the array has a combined nominal optical power output of 90 watts (W). Because UV LEDs are relatively inefficient, creating the 90W of optical power requires 1800W of electrical power. The waste heat from the LEDs is managed by a liquid-cooled plate and external chiller.Abstract
Contributor Notes
ABOUT THE AUTHORS
Wyatt Felt earned a BS from Brigham Young University in mechanical engineering and an MS and PhD in mechanical engineering from the University of Michigan – Ann Arbor. He was a postdoctoral fellow at EPFL, Switzerland's federal institute of technology in Lausanne. At VPI Technology, Dr. Felt has proposed and led millions of dollars of research and development work. Dr. Felt has been honored as a Crocker Innovation Fellow and as an NSF Graduate Research Fellow, and he was a founding member of Owlet Baby Care. Dr. Felt directed the project as the principal investigator and was primarily responsible for the optical design of the lamp and the lamp characterization and testing.
Contact Author: Wyatt Felt , wyattf@vpitech.com.
Kevin Marriott earned an MS in electrical engineering from the University of Utah with an emphasis in radio frequency (RF) and analog design. He has more than two decades of experience in the successful design of complex, high-power, analog, and RF systems, including extensive electromagnetic interference design. His experience includes designing probes for the Radiological Detection System, MIL-STD-461 testing, and design modifications to support compliance with MIL-STD-461. Mr. Marriott was the project's technical lead and directed the system architecture design, LED selection, and electrical design and testing.
Trenton Griffiths earned a BS in mechanical engineering from Utah State University with a minor in computer science. Trenton led the thermal and mechanical design of the lamp and collaborated with Dr. Felt to design and conduct the lamp testing. He also assisted with optical design, and carried out the ball-lens testing and thermal testing.
Charlotte Murphy graduated cum laude with a BS in computer science from Oregon State University. She also holds a BS in business administration and management from Utah Valley University. She created the software application to interface with the lamp and assisted with testing.
Bryce Lembke earned a BS in computer engineering from Brigham Young University. He has extensive experience in embedded firmware engineering. He wrote the firmware that controls the lamp electronics and assisted with software design and electrical testing.
Nathaniel Morris earned a BS in physics from Utah Valley University. He helped direct the progress of the project as a project manager.