The extraction of electrons from cold metals at high field-strengths

The paper is a résumé of the considerable amount of published work on the extraction of electrons from cold metals in high vacua by the application of high field-strengths. A sufficient description of the experimental technique is given to bring out the difficulties met with in attempts to correlate theory and practice. It is concluded that the Fowler-Nordheim theory is substantially correct in giving the dependence of field currents on the field strength and temperature, and also in respect of the energy distribution of the electrons involved. The extension of this relation to include the effect of electropositive surface films appears to be justified experimentally, though there is need of further quantitative confirmation. The significance of field emission in relation to breakdown phenomena, the mercury arc and materials of non-linear electrical characteristics is discussed. The authors trust that the list of references given is a complete one.