Excessively high costs of the available technical high temperature superconductors have so far prevented the product launch for this application. To be in a position to produce the considerable quantities of superconductors affordably, the novel Aerosol Deposition Method (ADM, also known as aerosol-based cold deposition) is applied in the DIAMANT project to the extremely promising high temperature superconductor material magnesium diboride (MgB2). The project is promoted by the German Federal Ministry for Education and Research (BMBF).
In the ADM method, the starting powder is dispersed as a particle aerosol and is spread over the substrate material under high low-pressure using a nozzle. Due to the high kinetic energy of the particles at the impact, they densify in-situ at room temperature to form layers. This allows the deposition of several tens of µm thick superconducting layers with high density and homogeneity.
In the joint project, Palas®, together with the project partners of the Karlsruhe Institute for Technology (KIT), Siemens AG and the University of Bayreuth, conducts basic research on the layer deposition process. The newly developed aerosol generators - RBG 1000 SD and RBG 2000 SD - allow the researchers for the first time adjustable, reproducible and constant dispersion of various starting powder also at low pressures down to 300 mbar.
Due to the oxygen-sensitive starting powder the researchers value, the high vacuum sealing and the flexible operation of the RBG generators with inert carrier gases such as nitrogen, helium or forming gas. By integrating a welas® digital 2000 aerosol spectrometer from Palas® in the overall ADM system, the particle size distribution of the dispersed aerosol was determined in-situ during the process, immediately upstream of the deposition nozzle at negative pressures down to 300 mbar. The scientists were therefore able to understand the influence of the various operating modes of the RBG on the particle size distribution and the number concentration. This allows important conclusions to be drawn about the layer and superconductor properties.
After completion of the project, the new insights will be presented, e.g. at the upcoming Aerosol Technology Conference 2018 in Bilbao. Further publications in scientific journals are also planned.