Advances in deuterium dioxide concentration measurement

Abstract The deuterium–tritium (D–T) reaction has been identified as the most efficient reaction for fusion devices. Deuterium can be obtained by heavy water electrolysis. Heavy water (D 2 O) with a high purity level is necessary for nuclear fusion application. A D 2 O isotopic analysis is thus very important. A system for a heavy water analysis was built and a newly designed isotopic analysis experiment was carried out. We tried to analyze the D 2 O purity using Fourier Transform infrared (FT-IR) spectroscopy and newly introduced off-axis integrated cavity output spectroscopy (OA-ICOS). We found that the OA-ICOS based on measurement via laser absorption spectroscopy shows very high sensitivity. We ameliorated the sensitivity by an order of magnitude of more than 10 3 –10 5 . We could make the apparatus smaller by employing very tiny diode laser and fiber optics elements of a DFB (Distributed Feedback) type. Consequently, our device has advantages in terms of maintainability and mobility even in a radioactive environment. This new method could be used for an accurate isotopic analysis in the future.