CryoSense: Sensor Validation Results in Liquid Nitrogen and Proposals for Upgrades of Measurement Technology

Abstract

This Technical Note presents the results of cryogenic sensor validation experiments in liquid nitrogen/liquid hydrogen and proposes upgrades to the measurement technologies. Electrical capacitance tomography and Ultrasound Tomography are for the first time introduced in cryogenic conditions. Functionality and performance for the detection of liquid levels and bubbles in liquid nitrogen (77K) are assessed. Sensor application and feed-through techniques are established. Fibre-optic temperature sensors are used to measure high resolution temperature profiles in the liquid and gas phase of nitrogen. The performance of three different fibre coatings is investigated and optimised. Finally, the sensor is used for vertical temperature profile measurements in the liquid and gas phase of hydrogen (20K). In the domain of fibre-optic technologies, fibre optic bundles used as image and light guides are tested in cryogenic conditions. They are operable in the cold gas phase above liquid nitrogen and, with suggested modifications, suitable for immersion in liquid nitrogen. Finally, upgrades to these measurement devices are proposed, with the goal of rendering them operable on microgravity platforms. Upgrades are also proposed for two further technologies (optical tomography based on optical fibres) and radio-frequency mass gauging.