Radiation Tolerant High Emissivity Coatings using Quantized Nanolaminates

Components in rare isotope beam production facilities, such as targets or beam stops, often operate at elevated temperatures under high radiation. High-emissive (High-E) coatings can help reduce the temperature of these components by enhancing radiative heat transfer. Raytum Photonics introduces an innovative approach to creating radiation-tolerant, high-emissivity thin-film coatings. By utilizing the super-cycle technique of Atomic Layer Deposition (ALD), we synthesize quantized nanolaminate thin films with an optimized combination of refractive index and extinction coefficient. This allows us to achieve emissivity greater than 0.9 with a coating as thin as 2.5 µm. Emissivity can be further improved by incorporating metal nanoparticles, a method Raytum Photonics has successfully demonstrated using ALD. The proposed coating is not only robust and reliable but also benefits from a highly conformal, cost-effective deposition process that is scalable for large components. Radiation tolerance is enhanced by using composite materials with elements that have low atomic numbers and small neutron absorption cross-sections. Additionally, the nanolaminate coating’s thin profile contributes to its superior radiation tolerance compared to traditional High-E coatings, which typically have a thickness of 50 to 100 µm. Raytum Photonics will experimentally demonstrate the proposed High-E coatings during the Phase 1 effort. The deposition process will be conducted using our Veeco S200 ALD system. We plan to deposit High-E coatings on various disc-shaped substrates, up to 8 inches in diameter for phase 1 demonstration. The emissivity of the samples will be measured using a thermal emissometer and a custom-built vacuum test chamber. To evaluate radiation tolerance, we will collaborate with DOE labs or a commercial service provider to apply the specified radiation dose. The radiation tolerance will be assessed by conducting a series of comprehensive tests, comparing the samples before and after radiation exposure.