Field of Interest: Material and Surface Science
The choice, production and maintenance of surfaces with the suitable properties are crucial requirements for the successful operation of the accelerators of CERN. The beam of charged particles is circulating in pipes under very high vacuum, reaching an overall length of 130 km. To ensure this level of vacuum, all such surfaces are prepared with precision cleaning or etching in a plant with appropriate chemical baths and in some cases a further thermal treatment is necessary to reduce gas release. The properties of the surface are often modified by covering it with adapted thin films produced by wet chemical or physical methods.
CERN has developed micrometre thick layers, which can contribute to pumping residual gases and improve the vacuum of the pipes. Other thin layers enable to operate with more stable beams and mitigate the emission of perturbing electrons from the walls in line of sight of the particle beam. In a further case, copper plating of the surfaces can improve the electrical conductivity. Last, but not least, specific analysis techniques, which can measure chemical composition and structure in the topmost layers of the materials, enable the quality control of the surfaces and diagnostics in case of non-conformities.
