Temperature Effects in Secondary Emission

Measurements have been made on the effects of temperature changes on the emission of secondary electrons from iron, nickel, cobalt, and molybdenum. Abrupt changes of one or two percent were observed to accompany the $\alpha -\gamma$ transition of iron, while the hexagonal to face-centered cubic transformation of cobalt was accompanied by a change in secondary emission of only about 0.4 percent. The magnetic transformation was found to alter the secondary emission coefficient of nickel by less than 0.3 percent. The temperature coefficient of secondary emission, in the case of nickel, cobalt, and molybdenum was found to be much less than the volume coefficient of expansion of the metal. The smallness of the temperature coefficient and the effect of the magnetic transformation are shown to lend support to the view that the secondary electrons are scattered or "absorbed" by an excitation process similar to that whereby they are originally produced.