Nanoparticle Coatings to Mitigate the Multipactor Effect in High-Frequency Devices [NanoMitigate]

Nanostine proposes an innovative and environmentally friendly solution for addresing multipactor effect issues in the aerospace industry. The current coating used to protect radio frequency devices, Alodine, needs to be replaced due to its hexavalent chromium content, which poses an environmental risk and does not comply with REACH requirements. Our proposed solution is to develop a rough coating with dual-scale roughness at the nanoscale, based on a combination of core@shell gold@silver nanoparticles and Au nanocolumns. The roughness generated by the geometry of the nanoparticle layers (few nm), combined with that of nanocolumns (tens of nm) will increase the probability of secondary electron capture and consequently the multipactor threshold. Additionally, the composition of the nanoparticles implies the use of silver, the best metal for electron capture, with an inert and much more stable gold shell, which prevents silver oxidation. This coating is expected to exhibit good properties such as low secondary electron emission, improved ageing resistance, and high conductivity while meeting environmental requirements. Nanostine's technology excels by producing high-quality nanoparticles with homogenous size distribution and composition that other methods cannot obtain. It is carried out under ultra-high vacuum conditions, ensuring cleanliness and minimising coating contamination. The process uses nanoparticle sources, also known as Gas Aggregation Sources, which generate an atom gas through magnetron sputtering plasma, recombined in a controlled way to generate nanoparticles that can be deposited on any vacuum-compatible surface. Using gold and silver nanoparticles as the basis for the coating is an innovative approach as it provides a unique combination of properties, including a high electron capture capacity and chemical stability over time. Moreover, by meeting environmental requirements, it becomes an environmentally friendly alternative to Alodine.