Periodic Reporting for period 1 - HEPHAESTUS (Heating Electric-fields in a Plasma CVD reactor to Heighten Ability to grow Eeco-friendly and Sublime Type IIA Diamonds (which are Unique Stones)) Reporting period: 2019-12-01 to 2020-04-30 Summary of the context and overall objectives of the project Diamonds represent a rare, luxury and expensive product used by both the high technology and jewellery industry. Diamonds are discovered underground in deep-earth mines, riverbeds and ocean floor. However, mining conditions raise ethical and environmental concerns that affect production. As a consequence, the diamond industry faces scarcity in raw materials. The EU-funded HEPHAESTUS project proposes an environmentally friendly and cost-effective method of growing diamonds in a laboratory. The innovative method consists of placing diamond seeds in a plasma chemical vapour deposition reactor that transforms carbon-containing gas into diamond. This advanced technology is based on non-equilibrium microwave plasma-activated chemical reaction process that allows growing high-quality diamonds, targeting the finest jewellery market. Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far HEPHAESTUS project started in December 2019 with the objectives of characterizing parameters for growth of Type IIa diamonds in microwave reactor operating at the wavelength of 915 MHz, developing tools to monitor diamond growth and assessing optimum trade-off between growth rate / number of diamonds per run. The project aimed also to extend coverage of a patent while carrying out a market study on the jewellery market for lab-grown diamonds and identifying distributors to broaden distribution channels.The main results showed that cut diamonds present colours strongly related to plasma parameters, in particular to plasma power density and impurities, as well as to deposition temperature. Temperature monitoring using an optical pyrometer coupled to an optical camera is essential during growth. Results open the possibility to enhance the Diam Concept patent. Photoluminescence has been shown to be an interesting method to evaluate the diamond colours after growth. Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far) Producing a large number of stones in a run requires a homogeneous plasma at the plasma surface interface that can be obtained through an optimization of the plasma cavity. Plasma simulation allows finding several possibilities of compromises to produce such requirements. Many plasma simulations have been realized based on a CNRS plasma code developed in the past.In agreement with our market study, the release of articles in French and international media now connect us with more than 80 jewellers and distributors interested by our lab-grown diamonds. Among them, the jeweller Courbet has launched, thanks to our diamonds, the first collection of jewellery with made in France diamonds. We will broaden the approach. Diamond
