A New Microwave Harmonic Generator

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IF my estimate1 of up to 107 amp./cm.2 for the emission current density of free cathode ‘spots’ on a clean mercury surface is accepted, the mercury arc may be regarded as an indestructible point-contact rectifier with interesting microwave properties. At high rates of growth of current (that is, in excess of 6 × 107 amp./sec.) the cathode emission appears to be unable to follow the rising current by its normal method of increasing size1 and presumably (at microwave frequencies) must either change its emission density or become unstable, or both. In either case a ‘non-linear’ current-voltage relationship is still to be expected.

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  1. 1

    Froome, K. D., Proc. Phys. Soc., B, 62, 805 (1949).

  2. 2

    Froome, K. D., Nature, 179, 267 (1957).

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FROOME, K. A New Microwave Harmonic Generator. Nature 184, 808 (1959) doi:10.1038/184808a0

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