Twin-CQCM and Twin-TQCM Sensors With Wide Operating Temperature Range for Outgassing and Atomic Oxygen Measurement

In this paper, we propose a new Quartz Crystal Microbalance (QCM) sensor with temperature control, which can assess outgassing properties during spacecraft development. It will be referred to as the “Twin-QCM sensor.” There are two types. The Twin-Cryogenic QCM (Twin-CQCM) sensor is warmed by a built-in heater with an operating temperature of −190 to $+ 125^{\circ }\text{C}$ , and the Twin-Thermoelectric QCM (Twin-TQCM) sensor is warmed and cooled by a built-in Peltier module that can control the temperature within −80 to $+ 125^{\circ }\text{C}$ . Using a temperature compensation technique, the temperature-dependent drift of the frequency was found to be less than ±10 ppm over all operating temperatures. An RTD temperature sensor was mounted on the quartz crystal to improve the accuracy of temperature measurement. To confirm the accuracy, an additional temperature sensor installed at the center of the crystal. The sensor output temperature value was compared to that of the additional sensor, with the difference between both temperature sensors being +0.4 to $+ 2.6^{\circ }\text{C}$ in the temperature range from −130 to $+ 100^{\circ }\text{C}$ . Through the measurement of the sensor’s dynamic range, it was found that the deposited contaminant film in a vacuum increasingly changed such physical properties as viscoelasticity as the temperature increases.