The thermionic emission from clean platinum

Abstract

The thermionic emission from thoroughly outgassed platinum in high vacuum has been measured to one-half percent over the temperature range 1360 to 1750°K, the temperatures being measured by careful optical pyrometry. The values obtained for the thermionic constants of the T2 law are, when corrected for the Schottky effect, b=72, 820°K, φ=6.27 volts, A=17,000 amp/cm^2 deg^2. The value of φ is possibly in error by not more than 1 percent because of uncertainties in the temperature scale, and agrees within one-half percent with the value of the photoelectric work function previously obtained. The data confirm the previous announcement that for clean platinum A is 250 times greater than the theoretical value of 60.2 amp/cm^2 deg^2.

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