Development of a millisecond pulse-heating apparatus

A millisecond pulse-heating apparatus is presently under development at the Harbin Institute of Technology (HIT). The design is based on systems previously developed both at NIST (U.S.A.) [1, 2] and IMGC (Italy) [3] for the measurement of several thermophysical properties with millisecond time resolution. The apparatus uses rapid resistive self-heating of a strip-shaped specimen from room temperature to a pre-chosen maximum temperature. Power is furnished by a subsecond-duration electrical current pulse through the specimen. Simultaneous measurements are carried out for several quantities. The maximum current is up to 2000 A. Experiments are performed on strip-shaped specimens with the following typical dimensions: 80 mm in length, 10 mm in width, and 1 mm in thickness. The specimen is contained in a large vacuum chamber (bigger than 300 mm in both diameter and height) whose inner wall is coated with a nonreflecting paint. A special designed high-speed pyrometer will be used to measure the temperature of the specimen through one of two quartz windows of the chamber. The heat capacity, the electrical resistivity, the total hemispherical emissivity, and normal spectral emissivity of the specimen are measured by using this apparatus for various materials.