STANFORD RESEARCH INST MENLO PARK CALIF ELECTROMAGNETICS LAB
AD-260 4129 AD-260 413Div. 8, 25U 1 Aug 61 OTS price 1.10 Ohio State U. Research Foundation, Columbus, Ohio. THE MECHANISM OF OXIDE FORMATION IN THE INITIAL STAGES OF OXIDATION. Quarterly rept. no. 4, 1 Apr-30 June 61, by D. W. Rausch, K. L. Moazed, and M. G. Fontana. 14 Apr 61, 3p. Contract DA 33-019-ORD-3387 Unclassified report DESCRIPTORS Tantalum, Tungsten, Oxides, Oxidation, Field emission, Gases, Gas diffusion, Temperature, High temperature research, Pressure, Adsorption, Resistance, Measurement, Vacuum apparatus, Electron tubes, Test methods, Tantalum compounds, Tungsten compounds. Field emission runs were made with W and Ta emitter tips fabricated from 4 to 6-mil-diam commercial grade W and Ta to observe the progress of adsorption of residual gases over a range of pressures and temperatures. Electrolytic polishing was used to produce the fine point required for emission. The tips were cleaned by resistive heating prior to emission. Field-evaporation was also utilized on Ta. The emission patterns of clean Ta and W tips were similar. The progress of adsorption of residual gases on W at elevated temperatures and constant pressure was observed. Work was initiated on the measurement of emitter tip temperature below 800 C by an electrical resistance method. A non-refrigerated, highvacuum, isolation trap was developed and successfully operated in the vacuum system.