A new facility to study the interaction of hydrogen isotopes with nuclear fusion relevant first wall materials, its retention and release, has been produced. The new facility allows implanting a range of gases into samples, including tritium. Accurate study of isotope effects, such as the isotopic exchange in damaged microstructure, has previously been difficult due to a background signal of light hydrogen. This new capability will allow virtually background free measurements using tritium and deuterium. The design and build of this facility are described and commissioning results are presented. Within the UKAEA-led Tritium Retention in Controlled and Evolving Microstructure (TRiCEM) project, this facility is used for comparative study of deuterium retention in self-ion irradiated Eurofer steel and Fe-Cr alloy. Self-ion bombardment with energies of 0.5 MeV is used to mimic the defects created by neutrons in fusion power plant and the created traps are then filled with deuterium in the new facility. Implanted samples are analysed using Thermal Desorption Spectrometry (TDS), Secondary Ion Mass Spectrometry (SIMS), and Transmission Electron Microscopy (TEM). Results on total deuterium content as function of time, TDS spectra and SIMS analysis are presented. Comparison of results for Eurofer and Fe-Cr revealed several differences. While some of them may be due to experimental details like different time delays between exposure and analysis, others, such as deuterium retention as function of dose, might be genuine and require further studies.

Surface transfer-doping, involving hydrogen terminated diamond surfaces, has been an effective method for producing diamond devices for some years but suffered from poor device longevity and reproducibility. The emergence of metal oxides as an encapsulant has begun to change this situation. Here, HfO2 encapsulated surface transfer doped diamond Schottky diodes with stable device characteristics have been demonstrated. Ideality factor and Schottky barrier heights of the devices did not vary considerably across extended periods of use (up to 39 days). The devices showed excellent blocking capabilities, demonstrating no catastrophic breakdown under the maximum field applied and only a slight increase in leakage current at the reverse bias and field strength of 200 V and [Formula: see text], respectively. Indeed, a large rectification ratio of up to 108 and a very low leakage current of [Formula: see text] were maintained at this reverse bias (200 V). Furthermore, multiple devices were compared across a single substrate, something rarely reported previously for surface transfer doped diamond diodes. Leakage currents and rectification ratios were similar for all of the devices.