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Index of refraction versus oxygen partial pressure for tantalum oxide and silicon dioxide films produced by ion beam deposition

Description: Tantalum oxide and silicon oxide films were made using an ion beam sputtering system. It was found that even though these films were deposited from oxide targets, additions of oxygen were necessary to achieve stoichiometry and hence index of refraction. It was observed that the tantalum oxide target changed color from white to gray, indicating that the oxygen was being depleted from the target. The addition of oxygen to the chamber during deposition replenished the target and improved film stoichiometry. The deposition rate decreased with increasing oxygen partial pressure. It was experimentally determined that by varying the oxygen partial pressure and keeping all other variables fixed, the index of refraction of the film changed in a predictable manner. That is, as the oxygen partial pressure was increased, the index decreased rapidly initially and then reached a saturation point where it stayed fixed with oxygen content. With this data a coating process can be set up using the minimum amount of oxygen (thus increasing filament lifetime) to produce a fully stoichiometric film that has a fixed index. This paper will present the details of these observations and results.
Date: April 30, 1998
Creator: Goward, W.D.; Petersen, H.E.; Dijaili, S.P. & Walker, J.D.
Partner: UNT Libraries Government Documents Department


Description: As a part of an ongoing activity to develop ASME Code rules for the hydrogen infrastructure, the ASME Boiler and Pressure Vessel Code Committee approved new fracture control rules for Section VIII, Division 3 vessels in 2006. These rules have been incorporated into new Article KD-10 in Division 3. The new rules require determining fatigue crack growth rate and fracture resistance properties of materials in high pressure hydrogen gas. Test methods have been specified to measure these fracture properties, which are required to be used in establishing the vessel fatigue life. An example has been given to demonstrate the application of these new rules.
Date: April 30, 2007
Creator: Rawls, G
Partner: UNT Libraries Government Documents Department

Analysis of internal pressure behavior as a function of vent size in a radioisotopic thermoelectric generator

Description: From joint meeting of the American Nuclear Society and the Atomic Industrial Forum and Nuclear Energy Exhibition; San Francisco, California, USA (11 Nov 1973). A theoretical investigation was undertaken to determine the effect of acceptable cladding vent sizes on the internal oxygen pressure in a PuO/ sub 2/ fuel sphere of a heat source capsule which consists of the fuel sphere clad in lr metal. The results are to be used in the design of a radioisotope- fueled thermoelectric generator for space applications (SNAP). The vents must be large enough to minimize the oxygen pressure in the sphere, thereby minimizing the transport of Ir, and, at the same time, small enough to prevent the escape from the capsule of particulate Pu. The vent is idealized as a short tube of length l and radius a. The flow equations assume transitional viscous-molecular flow through such a shont tube. The results indicate that a vent with a l/a ratio of S significantly improves the oxygen exhaust rate in the fuel capsules as compared to smaller vent sizes and should solve the problems resulting from the transport of iridium. (LCL)
Date: April 30, 1974
Creator: Travis, J.R.; Peterson, D.E. & Mulford, R.N.R.
Partner: UNT Libraries Government Documents Department