Letter | Published:

Ionisation by Positive Ions



IN recent years many theories of discharges in gases have been proposed which do not afford a consistent explanation of the principal properties of currents obtained in gases under various conditions. According to a theory which has been much advocated,1 it is said that atoms of the gas are not ionised by single impacts of electrons in discharges at pressures greater than that corresponding to the minimum sparking potential, since the electrons lose their energies in producing metastable atoms and therefore cannot attain the ionising potential. So far as the action of electrons is concerned, it has already been shown that this theory of collisions is inconsistent with the ordinary properties of glow discharges.2

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  1. 1

    T. R. Merton and J. G. Pilley, Proc. Roy. Soc., A, 107, 411; 1925. R. d'E Atkinson, Proc. Roy. Soc., A, 119, 335; 1928.

  2. 2

    J. S. Townsend and S. P. McCallum, Phil. Mag., 5, 695; 1928. Proc. Roy. Soc., A, 124, 533; 1929.

  3. 3

    J. Taylor, Proc. Roy. Soc., A, 14, 73; 1927. K. Zuber, Ann. Phys. (l2), 6, 665; 1932.

  4. 4

    Sir J. J. Thomson, Phil. Mag., 48, 1, July 1924.

  5. 5

    J. S. Townsend, Phil. Mag., 45, 444, March 1923. L. G. H. Huxley, Phil. Mag., 3, 1056, and 4, 899; 1927.

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