Enhanced Infrared Emission by Thermally Switching the Excitation of Magnetic Polariton with Scalable Microstructured VO 2 Metasurfaces
Year: 2020
Type: article
Abstract: Dynamic radiative cooling attracts fast-increasing interest due to its adaptability to changing environment and promises for more energy-savings than the static counterpart. Here we demonstrate enhanced infrared emission by thermally switching the excitation of magnetic polariton with microstructured vanadium dioxide (VO 2 ) metasurfaces fabricated via scalable and etch-free processes. Temperature-dependent infrared spectroscopy clearly shows that the spectral emittance of fabricated tunable metasurfaces at wavelengths from 2 to 6 μm is significantly enhanced when heated beyond its phase transition temperature, where the magnetic polariton is excited with metallic VO 2 . The tunable emittance spectra are also demonstrated to be insensitive to incidence and polarization angles such that the VO 2 metasurface can be treated as a diffuse infrared emitter. Numerical optical simulation and analytical inductance-capacitance model elucidate the suppression or excitation of magnetic polariton with insulating or metallic VO 2 upon phase transition. The effect of enhanced thermal emission with the tunable VO 2 metasurface is experimentally demonstrated with a thermal vacuum test. For the same heating power of 0.2 W, the steady-state temperature of the tunable VO 2 metasurface emitter after phase transition is found to be 20 °C lower than that of a reference V 2 O 5 emitter whose static spectral emittance is almost the same as that of the VO 2 metasurface before phase transition. The radiative thermal conductance for the tunable metasurface emitter is found to be 3.96 W/m 2 K with metallic VO 2 at higher temperatures and 0.68 W/m 2 K with insulating VO 2 at lower temperatures, clearly demonstrating almost 6-fold enhancement in radiative heat dissipation.
Source: ACS Photonics
Authors: Linshuang Long, Sydney Taylor, Liping Wang
Institution: Arizona State University
Language: English
Subfield: Civil and Structural Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: green
Awards: DURING THE COURSE OF ITS MISSION A SPACECRAFT IS OFTEN EXPOSED TO SIGNIFICANT THERMAL CYCLING. HARDWARE COMPONENTS SUCH AS BATTERIES TRANSMITTERS ETC. WILL ONLY OPERATE WITHIN A COMPARATIVELY SMALLER RANGE OF TEMPERATURES. THEREFORE A THERMAL MANAGEMENT SYSTEM (TMS) MUST BE DEVELOPED TO MAINTAIN THE SPACECRAFT'S TEMPERATURE AT AN OPERABLE LEVEL THROUGHOUT THE MISSION. ONE FUNCTION OF THE TMS IS TO REGULATE THE SPACECRAFT'S RADIATIVE HEAT TRANSFER WITH THE ENVIRONMENT. PASSIVE RADIATION COATINGS ARE A DESIRABLE WAY TO ACHIEVE THIS SINCE THEY REQUIRE NO ELECTRICAL INPUT AND TYPICALLY ADD A NEGLIGIBLE AMOUNT OF MASS. THIS PROPOSAL DISCUSSES WAVELENGTH-SELECTIVE TEMPERATURE-MODULATED MULTILAYER COATINGS WHICH CAN BE USED TO CONTROL THE RADIATIVE HEAT TRANSFER BETWEEN THE ENVIRONMENT AND THE SPACECRAFT. IF THE SPACECRAFT'S TEMPERATURE IS TOO HIGH THE RADIATION COATING CAN HELP TO REDUCE THE TEMPERATURE THROUGH ENHANCED THERMAL EMISSION BY SELECTIVELY EMITTING IN THE MID-INFRARED. CONVERSELY IF THE SPACECRAFT TEMPERATURE IS TOO LOW A HIGHLY REFLECTIVE RADIATION COATING CAN PREVENT FURTHER TEMPERATURE DECREASE BY MINIMIZING THERMAL LOSS. THE PROPOSED COATINGS WILL COMBINE BOTH FUNCTIONALITIES TO PROVIDE TEMPERATURE-MODULATED VARIABLE EMISSIVITY AND IMPROVED THERMAL CONTROL. THE TEMPERATURE-MODULATED PROPERTIES ARE ACHIEVED THROUGH THE INCORPORATION OF A THERMOCHROMIC TRANSITION MATERIAL VANADIUM DIOXIDE. CURRENTLY A FABRY-PEROT RESONANCE CAVITY PROVIDES THE WAVELENGTH-SELECTIVITY OF THE DESIGN HOWEVER OTHER STRUCTURES SUCH AS NANOPARTICLE LAYERS GRATINGS AND NANOPILLARS WILL BE INVESTIGATED. ALTERNATIVE TUNABLE MATERIALS SUCH AS GRAPHEME OR OTHER TRANSITION MATERIALS WILL ALSO BE EXPLORED. THIS MULTIFACETED PROPOSAL COVERS FOUR AREAS: COATING DESIGN SAMPLE FABRICATION AND CHARACTERIZATION METROLOGY DEVELOPMENT AND DEVICE LEVEL TESTING. A GENERAL METHODOLOGY TO ANALYZE AND OPTIMIZE MULTILAYER RADIATION COATINGS THAT INCORPORATE A THERMOCHROMIC TRANSITION MATERIAL HAS ALREADY BEEN DEFINED AND USED TO MODEL THE RADIATIVE PROPERTIES OF SEVERAL PRELIMINARY STRUCTURES. LIKEWISE DEVELOPMENT OF THE METROLOGY SYSTEMS NEEDED TO CHARACTERIZE THE SAMPLES RADIATIVE PROPERTIES INCLUDING AN ALL-IN-ONE CRYOGENIC-TOHIGH-TEMPERATURE SPECTROSCOPIC PLATFORM IS IN PROGRESS. VARIABLE EMISSIVITY COATINGS WILL BE FABRICATED CHARACTERIZED TESTED AT THE SYSTEMS LEVEL AND ITERATIVELY IMPROVED TO DELIVER A DYNAMIC RADIATIVE COATING WHICH HAS THE POTENTIAL TO SIGNIFICANTLY ADVANCE NASA'S EXPLORATORY MISSION CAPABILITIES. THE FINDINGS OF THIS RESEARCH WOULD ADDRESS THE TA14.2 SPACE TECHNOLOGY ROADMAP OBJECTIVE., G8216501429
OpenAlex ID: W3041244092