A New Thermocouple Thermometer

Abstract

An accurate thermometer with fast response and high reliability has been designed and built by using a very fine copper-iron thermocouple coated with sputtered gold, and a newly available ultralow drift operational amplifier. The newly designed thermometer has attained an accuracy of about 0.04°C (one standard deviation, with both the surroundings of the oven and the circuitry at room temperature) and is estimated to attain a time constant of 4 ms in a 20 m s?1 airflow. This thermometer was originally designed for airborne use to measure temperature in cloud, but the thermometer could be used for other applications, especially those which need high-accuracy, fast response time, and a small sensing element which does not change calibration if the sensing wires are stretched by the impaction of particles in a flowing fluid. The most important use envisaged is to mount it on an aircraft to examine the entrainment process at the top surfaces of clouds. It is hoped to also develop a wet-bulb version for such use.