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X-Ray Spectrometric Determination of Composition and Distribution of Sublimates in Receiving-Type Electron Tubes*

Published online by Cambridge University Press:  06 March 2019

Eugene P. Bertin
Affiliation:
Radio Corporation of America Harrison, New Jersey
Rita J. Longobucco
Affiliation:
Radio Corporation of America Harrison, New Jersey
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Abstract

During the normal operation of conventional receiving-type electron tubes, certain metallic elements, such as barium, strontium, nickel, and manganese, sublime from the hot cathode and deposit on cooler parts of the tube. This process gradually impairs the performance of the tube and may eventually limit its useful life. This paper describes some applications of a variety of X-ray spectrometric techniques to the qualitative and quantitative analysis of these sublimates and to the mapping of their distribution on various surfaces in the tubes.

All work was done on a standard commercial X-ray spectrometer, but specially designed accessories are described for mounting and rotating small parts in the primary X-ray beam and for confining the beam to these parts. Procedures are given for analysis of microgram deposits on electron-tube cathodes, grids, plates, micas, and bulbs by both nondestructive and filter-paper-disk techniques. Procedures are given for point-by-point mapping of the distribution of sublimates over the surfaces of these parts by use of a commercial “X-ray probe” selectedarea accessory in conjunction with a curved crystal to give increased intensity. Procedures are given for various techniques for calibrating all the analytical methods, including preparation of thin films of known composition.

The results of some typical electron tube studies are described and illustrated. The approximate sensitivity of the methods for determination of total sublimate is, in micrograms per part, 0.1 for barium, strontium, and manganese and 0.05 for nickel. The approximate sensitivity for mapping sublimate distribution with a 1-mm aperture is, in micrograms per square centimeter, 1 for barium, strontium, and manganese and 0.5 for nickel. Although the techniques described are applied specifically to sublimates in electron tubes, they are also readily applicable to analysis of specks and films on other small parts and to thin-film studies in general

Type
Research Article
Copyright
Copyright © International Centre for Diffraction Data 1963

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Footnotes

*

Some of the text and most of the figures in this paper have appeared previously in Advances in Electron Tube Techniques Volume 2 and appear here through the courtesy of Pergamon Press and New York University Engineering Research Division, Electron Devices Group.

References

1. Btewett, J. P., Liebhafsky, H. A., and Hennelly, E. F., “The Vapor Pressure and Rate of Evaporation of Barium Oxide,” J. Chem. Phys. 7: 478, 1939.Google Scholar
2. Bever, R. S., “Diffusion of Barium in an Oxide-Coated Cathode“J. Appl. Phys. 24: 1008, 1953.Google Scholar
3. Hall, J. W. et. al., “A Study of Films in Electron Tubes,” Dept. of the Navy, Bureau of Ships, Contract NObsr-81225, General Electric Co., Receiving Tube Dept., Owensboro, Ky.; Final Rept. July 1962.Google Scholar
4. Hall, J. W. et al., op. cit., Second Quarterly Rept, November 1960.Google Scholar
5. Hall, J. W. et al, op. cit., Fifth Quarterly Rept. July 1961.Google Scholar
6. Liebman, A. M., “Optical Emission Spectrographic Method for the Analysis of Microgram Deposits on Electron Tube Parts,” Anal. Ckem. 34: 1370, 1962.Google Scholar
7. Wooten, L. A., Ruehle, A. E., and Moore, G. E., “Evaporation of Barium and Strontium from Oxide-Coated Cathodes,” J. Appl. Phys. 26: 44, 1955.Google Scholar
8. Schrader, E. R. et al, “A Study of Electron Tube Deterioration Utilizing Kinetic Theory,” Dept. of the Navy, Bureau of Ships, Contract NObsr-77637; Radio Corp, of America, Electron Tube Div., Harrison, N. J. ; Third Quarterly Rept. 1 April 1960.Google Scholar
9. Schrader, E. R. et al, op. cit., Final Rept. 1 January 1962.Google Scholar
10. Raag, V., Bertin, E. P., and Longobucco, R., “Distribution of Cathode Sublimation Deposits in a Receiving Tube as Determined by X-Ray Spectrometric Scanning,” Advances in Electron Tube Techniques 2: 249, 1963.Google Scholar
11. Hall, J. W. et al, op. cit. (see ref. 3), Sixth Quarterly Rept. November 1961.Google Scholar
12. Pelchowitch, I., “Study of the Evaporation Products of Alkaline Earth Oxides,” Philips Research Repts. 9: 42, 1954.Google Scholar
13. Russell, P. N. and Eisenstein, A. S., ‘Thermionic Emission and Electron Diffraction from Thin Films of Barium Oxide,“J. Appl. Phys. 25: 954, 1954.Google Scholar
14. Gobin, M., “Detection and Identification of Distillates in Tubes,” Le Vide 10: 263, 1960.Google Scholar
15. von Hamos, L., “X-Ray Microanalyzer Camera,” Trans. Roy. Inst, Tecknol. Stockholm 68: 3, 1963.Google Scholar
16. Duncumb, P., “Electron Probe Methods of X-Ray Microanalysis,” Brit. J. Appl. Phys. 11: 169, 1960.Google Scholar
17. Melford, D. A. and Duncumb, P., “Application of X-Ray Scanning Microanalysis to Some Metallurgical Problems,” Metallurgia 61: 205, 1960.Google Scholar
18. Heinrich, K. F. J., ‘'X-Ray Probe with Collimation of the Secondary Beam,” Advances in X-Ray Analysis, Vol. 5, University of Denver, Plenum Press, 1962, p. 516.Google Scholar
19. Bertin, E. P. and Longobucco, R. J., “Some Special Sample Mounting Devices for the X-Ray Fluorescence Spectrometer”, Advances in X-Ray Analysis, Vol. 5, University of Denver, Plenum Press, 1962, p. 447.Google Scholar
20. Finnegan, J. J., “Thin-Film X-Ray Spectroscopy,” Advances in X-Ray Analysis, Vol. 5, University of Denver, Plenum Press, 1962, p. 500.Google Scholar