科研之友
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摘要
Various thermal measurement methods utilizing the Peltier and the Seebeck effects of metallic junctions are introduced. The Peltier ac calorimeter employs two thermocouple junctions as a heater and a separate sensor; it allows the absolute value of heat capacity of small solid samples with sub-milligrams of mass to be measured. The Peltier tip calorimeter employs a Peltier tip, which is a single thermocouple junction functioning as a heater and sensor simultaneously. The Peltier tip calorimeter can measure the thermophysical properties not only of solids but also of fluids. When a Peltier tip is used to measure gas pressures, it is termed a Peltier vacuum gauge (PVG); the PVC measures gas pressure by utilizing both Joule heating along the wire and the Peltier effect at the junction. The complementary nature of the Peltier effect and Joule heating allows the PVC to possess an excellent sensitivity over a wide range of pressure from 10(-4) Torr to atmospheric pressure. Finally an acceleration sensor using the natural heat convection pattern from heated resistive wires in a gas as a marker of the reference frame is introduced. By flowing a sufficient dc current through the two leads of a cross-shaped thermocouple junction placed in a gas to generate natural heat convection and by measuring the temperature of the junction with the other two leads, one can detect acceleration. Miniaturization of the gas convection acceleration sensor is described.
- 出版日期2008-12
