Material Properties Compliance with Cryogenic Vacuum for Particle Accelerators

The use of any materials in particle accelerators requires a rigorous evaluation of their behavior in vacuum, especially when used at cryogenic temperatures. Laser treated copper substrates offer unquestionable advantages for electron-cloud mitigation purposes due to their low secondary electron yield. Here, the author investigates their vacuum behavior for the occurrence of small temperature transients during accelerators' performance. To this aim, a campaign of thermal programmed desorption measurements of CO and CH4 dosed on a laser treated copper substrate and on its flat counterpart has been launched. The preliminary results here reported show that the desorption of such gases from the laser treated substrates occurs in a much broader and higher temperature range with respect to what is observed from the flat substrate. This can be ascribed to their nanostructured porous morphology. These findings are particularly relevant since they refer to gases present in the residual vacuum of any accelerator system. They suggest that vacuum transient effects against temperature fluctuations should be better evaluated if such a surface would be used in accelerators' cryogenic vacuum.