POWER MODULATION TECHNIQUE FOR NONCONTACT HIGH-TEMPERATURE CALORIMETRY

A new noncontact calorimetric method has been developed based on induc tive heating of a metallic spherical bulk sample by a power-modulated radio-frequency field under ultrahigh vacuum conditions. From the pyro metrically measured temperature response the specimen's external (due to radiative heat loss) and internal relaxation time (due to thermal c onductivity) are found to differ by more than two orders of magnitude allowing the specific heat as well as thermal conductivity of the samp le to be determined as a function of temperature. The agreement betwee n the measured and predicted temperature response for solid Nb demonst rates the applicability and accuracy of the method which is particular ly useful for metastable or chemically reactive samples at high temper ature.