A STUDY OF FILMS IN ELECTRON TUBES
GENERAL ELECTRIC CO OWENSBORO KY
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A new method was developed for analyzing surface films on anodes, grids, and micas before exposing the tube parts to a gaseous environment. Several crystalline films on anodes and grids were identified, including MgO, BaSiO3, Al2O3, NiO, and others. Optical emission spectrography was adapted to the study of grid films and the analysis of the migration of cathode impurities. Eleven elements, Mg, Si, Mn, Ti, Fe, Co, Al, Cu, Ag, Cr, and Ba were measured quantitatively by this technique. Neutron activation techniques are being employed primarily to mica surface films and to grid films. Co-60, Na-24, and Sc-46 were identified on the surface of MgOcoated micas. Na was also present in the grids in rather high concentrations. Increases in Mn and Na were detected in grids during life. A fairly good calibration of the crystal oscillator film monitor was accomplished by evaporating Au on the quartz crystals and determining the quantity of Au by neutron activation.