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Application of a magnetic mass spectrometer to ionization studies in impure shock-heated argon

Published online by Cambridge University Press:  28 March 2006

B. Sturtevant
B. Sturtevant
Affiliation:
Graduate Aeronautical Laboratories, California Institute of Technology, Pasadena, California
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Abstract

A study of the unique role of impurities in the initial stages of ionization relaxation in shock-heated argon, using a sampling mass spectrometer to determine the ionic products of the reaction, is described. The ions are extracted from the shock tube through a small orifice in the end wall after they have diffused through the dense thermal layer adjacent to the wall from the ionizing gas behind the reflected shock wave. The ion diffusion is analysed in detail to assess the possibility that the sampling process alters the reaction products. It is shown that this is unlikely because the impurities are in dilute concentration and the reaction is studied in its initial stages. This mode of sampling is compared with others.

The experiments were conducted in argon at temperature of 16,600 °K and pressure of 16 mmHg with an estimated impurity level of 300 parts per million. A surprisingly large number of different ions were detected during the initial stages of ionization. O+ and H+ were found in much greater amounts than any of the other products, each being about five times more abundant than A+. The results suggest that H2O is probably quite generally the most important impurity in thermal-ionization experiments, and that ionization ‘incubation’ is due to dissociation of molecular impurities (especially H2O) before ionization commences. Possible explanations of the well-known efficiency of small amounts of impurities in initiating ionization are discussed.

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 25 , Issue 4 , August 1966 , pp. 641 - 656
Copyright
© 1966 Cambridge University Press

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References

Amdur, I. & Mason, E. A. 1958 Phys. Fluids, 1, 370.
Bier, K. & Hagena, O. 1963 Rarefied Gasdynamics, p. 478 (ed. J. Laurmann). New York: Academic Press.
Blackman, V. H. & Niblett, G. B. F. 1961 Fundamental Data Obtained from Shock-Tube Experiments, p. 221 (ed. A. Ferri). New York: Pergamon Press.
Bradley, J. N. & Kistiakowsky, G. B. 1961 J. Chem. Phys. 35, 25.
Fay, J. A. 1964 The High Temperature Aspects of Hypersonic Flow, p. 590 (ed. W. C. Nelson). New York: Pergamon Press.
Fay, J. A. & Kemp, N. H. 1965 J. Fluid Mech. 21, 65.
Fenn, J. B. & Deckers, J. 1963 Rarefied Gasdynamics, p. 497 (ed. J. Laurmann). New York: Academic Press.
Fite, W. L., Smith, A. C. H. & Stebbings, R. F. 1962 Proc. Roy. Soc. A, 268, 527.
Goldsworthy, F. A. 1958 J. Fluid Mech. 5, 196.
Harwell, K. E. & Jahn, R. G. 1964 Phys. Fluids, 7, 214.Corrigendum p. 1554.
Hasted, J. B. 1952 Proc. Roy. Soc., A 212, 235.
Hasted, J. B. 1965 Physics of Atomic Collisions, p. 421. London: Butterworths.
Hirschfelder, J. O., Curtiss, C. F. & Bird, R. B. 1954 Molecular Theory of Gases and Liquids, p. 518. New York: John Wiley and Sons, Inc.
Kelly, A. J. 1965 Private communication.
Liepmann, H. W., Roshko, A., Coles, D. & Sturtevant, B. 1962 Rev. Sci. Instr. 33, 62.
Massey, H. S. W. & Burhop, E. H. S. 1952 Electronic and Ionic Impact Phenomena, p. 625. Oxford University Press.
Nier, A. O. 1940 Rev. Sci. Instr. 11, 21.
Nier, A. O. 1947 Rev. Sci. Instr. 18, 39.
Petschek, A. & Byron, S. 1957 Ann. Phys. (N.Y.), 1, 270.
Sturtevant, B. 1961 Phys. Fluids, 4, 1064.