HEATED BODY-TEMPERATURE MEASUREMENT BY SPECTROMETRY OF PHOTOELECTRONS

It is shown that the heated body temperature can be measured from the energy distribution of photoelectrons appearing in the photoelectric d evice which serves simultaneously as detector and analyser of the body radiation spectrum. The effective wavelengths of this temperature mea suring technique cannot be chosen arbitrarily because they are functio ns of the temperature and must be measured. A technique for measuring the series of values of the effective wavelengths lambda(r)(T), which is necessary for estimation of the procedural error Delta T-ph, has be en proposed. The latter depends on the type of spectral characteristic of the photodetector, the energy photoelectron dispersion D in a reta rding field and the emissivity of a heated surface epsilon(lambda, T). The formulae for the procedural error calculation are obtained and th e latter has been shown to be less than that for measuring the tempera ture by conventional optical pyrometry methods and almost independent of temperature; Delta T-ph approximate to 2-3 K for tungsten (when T = 1200-2600 K) and Delta T-ph approximate to 3-5 K for platinum (when T = 1200-1800 K). The calculated results have been proved by series of experiments. A photoemissive pyrometer based on this method can be emp loyed for temperature measurements when the exact meaning of a changea ble emissivity is unknown as it takes place, for example, at pulse hea ting processes.