High Albedo Coatings
Development of Reflecting Coating, Resistant to the Light in the Wavelength Range from 0.2 to 3.0 Microns with the Energetic Albedo Close to Unit and Damage Threshold above 1MW/cm2
Tech Area / Field
3 Approved without Funding
VNIIEF, Russia, N. Novgorod reg., Sarov
- Lawrence Livermore National Laboratory, USA, CA, Livermore
Project summaryAt RFNC-VNIIEF there are special developments of reflective and protecting coatings, based on fiber glass and powdered materials, . In the world practice some of the powdered materials have found their application in reflectors, . The limitations of the reflectors specified include complexity of manufacturing the reflector of needed configuration and its attachment to any substrate. In our case this problem is solved using a heat - resistant adhesive - sodium silicate (NaO2-nSiO2).
The objective of Project is to obtain reflecting coatings with a high diffuse-reflection factor in a wide spectral range capable to withstand high thermal loads and temperature gradients without a loss in reflecting properties. These coatings will be based on advanced developments in which fiber glass, silica (SiO2), magnesia (MgO), barium sulphate (BaSO4) and etc. are used. The coatings under development will be applied in illuminating devices where high reflectivity under high thermal and vibration shock load is needed.
In illumination engineering, e.g., hi illuminators for various lasers and in various reflectors, usually polished aluminum serves as the reflecting surface of reflectors with the maximum reflection coefficient R»0.8. Under the action of pump radiation the reflector surface oxidizes and the reflection coefficient falls abruptly and thus repeated surface polishing becomes a necessary condition. Besides, mirror reflectors do not always provide uniform pumping because of undesirable light focusing in various regions of the active medium. In the above areas of technique the proposed coatings under development are indispensable.
The ten-year usage of one of the coatings developed on the laser facility ISKRA-5 [3, 4] demonstrates the stability of a high diffuse-reflection factor and good damage resistance after 1500 irradiation cycles.
The coatings under development based on various heat-resistant components differ from the available coatings in the following parameters:
- a higher diffuse reflection coefficient R»0.95 in a wide spectral region from 0.2 to 3.0 microns;
- high damage resistance with the damage threshold above IMW/cm2;
- high heat resistance above 1000° C.
In the process of investigation there will be considered coatings with various heat resistant components and the possibilities will be studied of depositing them on various refractory substrates. The executors are sure that the goals of Project will be achieved. This assurance of success is based on research results which were obtained in preceding years applied in various laser facilities included in dissertation works and published in various scientific articles, .
The coatings under development can find a use in the illumination engineering as reflective or light-protective coatings, in the systems of optical pumping for high-power lasers, and as heat-reflecting coatings in technique, where high heat and shock resistance is required simultaneously.
1. Guzov I.P., Punin V.T., Khudikov N.M. Author's certificate SSSR, № 1805435. Bulletin "Izobretenia", № 12, 1993.
2. Palmer R.E., Padrick Т.О., Pettit R.B. Journal Applied Physics, vol.48, № 7. 1977, p.3125-3126
3. Kirillov G.A., Murugov V.M., Punin V.T., Shemyakin V.I. Laser and Particle Beams, 8(4), 827, 1990.
4. Guzov I.P., Khudikov N.M., Kirillov G.A., Punin V.T. "Large aperture iodine lasers". SPIE, vol.2095, Laser Physics (1993), p. 125. (June 1993, Lasers Optics '93, St. Petersburg, Russia.)
As a result of Project accomplishment, we shall have:
1) specimens of long-lived coatings on steel, aluminum, ceramic and organic substrates;
2) specimens of long-lived coatings on various textiles;
3) Technical Report on development and investigation of specimens of coatings developed.
As a result of Project accomplishment there will be worked out recommendations for using the developed coatings in various areas of science and engineering which will meet the requirements of various customers working with such coatings. The results of work will be of great practical value.
Technical Approach and Methodology
The proposed work on Project is based on experience accumulated by specialists of RFNC-VNIIEF in the development of reflective and heat reflecting coatings during works on creating powerful laser facilities and designing optical elements with the use of modern materials.
The executors of works have rich experience in creating and designing reflective coatings on metal, ceramic and organic substrates.
Investigations and testing of coatings will be performed on the available at RFNC-VNIIEF experimental test beds provided with modern complexes of diagnostic and measuring equipment. Coatings will be tested by specialists using the available techniques.
During accomplishment of works on Project the available developments will undergo considerable modernization with the aim to increase the damage threshold, mechanical strength, heat resistance and coatings life-time under irradiation. The coatings under development will find use in illuminating devices where high reflectivity is needed at high thermal and vibration-shock load.
In the process of work on Project the research results will be regularly submitted in the form of reports scientific articles, they will be discussed during working meetings with the foreign collaborators.
Expected foreign collaboration
There were not any foreign collaborators before because of specific status of the Russian Federal Nuclear Center.
RFNC-VNIIEF will collaborate during this Project realization with any institution and foreign companies having an interest in it.
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