Measurement of Total Hemispherical Emittance at Cryogenic Temperatures

A method for measurement of total hemispherical emittance of metals at cryogenic temperatures is described. The principle of the measurement is based on calorimetric method and total hemispherical emittance as a function of temperature is obtained by measuring the equilibrium temperature of a specimen corresponding to different heat input, which is given to a heater attached to the specimen.

Measurements of total hemispherical emittance and specific heat have been carried out on the specimen of lead over a temperature range of 10∼40 K. In order to verify the measurement method, uncertainty on heat loss is discussed.