Development of an electrochemical sensor for hydrogen detection in liquid lithium for IFMIF-DONES

Hydrogen impurities in liquid lithium have a drastic disadvantageous impact on the used structural materials. Such a problem might occur also in the planned materials testing facility IFMIF-DONES, where hydrogen isotopes are produced by a reaction of a deuteron-beam with a target of liquid lithium. Therefore, the operation of such a Li-system requires the measurement of hydrogen (seen as impurity in the Li-melt) and the control of hydrogen removal. It is one of the excellences of the tool Electrochemistry to measure dissolved species over wide ranges of concentrations in real-time conditions. This presentation will present the physical background of determining non-metallic impurities in molten metals by measuring electrochemical potentials, outlining the development of such an H-sensor system and the transformation by Nernst correlation into concentration values. Additionally, liquid lithium is a very reactive melt, thus material compatibility is an essential topic for the developments of a durable sensor. Based on these issues a sensor design for measuring hydrogen in liquid lithium was realized under consideration of all physical, chemical and metallurgical aspects, including the successful manufacturing of the sensor as a first prototype and a further first production series. The outlook will also deal with the possibility of measurements of different hydrogen isotopes.