Browsing by Author "Merli, Stefan"

Filter results by typing the first few letters
Now showing 1 - 2 of 2
  • Thumbnail Image
    ItemOpen Access
    Experimental progress in the development of a metal foil pump for DEMO
    (2023) Kathage, Yannick; Vazquez Cortes, Alejandro; Merli, Stefan; Day, Christian; Giegerich, Thomas; Hanke, Stefan; Igitkhanov, Juri; Schulz, Andreas; Walker, Matthias
    Experimental findings to contribute to the preliminary design of a metal foil pump for fuel separation in the Direct Internal Recycling loop of the DEMO fusion device are presented. In parametric studies on a small-scale superpermeation experiment with a microwave plasma source and two different metal foil materials, niobium Nb and vanadium V, a substantial increase in permeation with plasma power and with a decrease in pressure was observed. To ease operation in the typical fusion environment, in-situ heating procedures were developed to recover from impurity contamination. The temperature independence of plasma-driven permeation from 600 to 900 °C metal foil temperature was demonstrated. No proof of an isotopic effect for plasma-driven permeation of protium and deuterium could be found. The highest repeatable permeation flux achieved was 6.7 Pa∙m3/(m2∙s) or ~5.5 × 10-3 mol H/(m2∙s). The found compression ratios do safely allow the operation of the metal foil pump using ejector pumps as backing stages for the permeate. In a dedicated experimental setup, the operation of the plasma source in a strong magnetic field was tested. Parametric studies of pressure, power input, magnetic flux density, field gradient and field angle are presented.
  • Thumbnail Image
    ItemOpen Access
    Novel microwave plasma source for plasma chemistry in gases
    (2025) Schulz, Andreas; Wiegers, Katharina; Troia, Mariagrazia; Bresser, Marc; Merli, Stefan; Walker, Matthias; Tovar, Günter
    In order to reduce the use and combustion of fossil raw materials, increasing reliance must be placed on renewable energies. Many strategies are currently being researched to enable the use of electrical energy from renewable resources for chemical synthesis [1, 2]. This contribution shows the possibility of obtaining basic chemicals by conversion using microwave plasma technology. A challenge for renewable energies, in addition to the storage problem, is the dependence on weather conditions. The plasma technology approach provides excellent flexibility in controlling of the process and thus in utilizing the fluctuating availability of cost‐effective renewable energies. This enables efficient and on‐demand operation.