Letter | Published:

Anomalous Dielectric Constant of Artificial Ionosphere

Naturevolume 140pages586587 (1937) | Download Citation



SINCE the earliest experiments of Barton and Kilby1 in 1913 on the dielectric properties of ionized air, there have been many attempts by investigators to record experimentally the depression of the dielectric constant of an artificial ionosphere (as the ionized air in a discharge tube may more properly be called) to a value less than unity. It has, however, been found by almost every investigator that the reduced value of the dielectric constant could be obtained only under very special experimental conditions such as low value of ionization in the experimental discharge tube or ultra-high frequency of the exciting wave ; while, more often than not, the value of the dielectric constant recordeol was greater than unity. This latter result is usually believed to be contradictory to the theory, and various explanations have been put forward to explain the apparent anomaly.

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  1. 1

    Barton, E. H., and Kilby, W. B., Phil. Mag., 26, 567 (1913).

  2. 2

    White, F. W. G., “Electro-magnetic Waves” (Methuen and Co., 1934), p. 58.

  3. 3

    Appleton, E. V., and Chapman, F. W., Proc. Phys. Soc., 44, 253 (1932). (The remark quoted is for the case of no external magnetic field.)

  4. 4

    Mitra, S. K., and Banerjee, S. S., NATURE, 136, 512 (1935).

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  1. University College of Science, 92 Upper Circular Road, Calcutta

    • S. K. MITRA
    •  & K. K. ROY


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