F. Le Pimpec 1 How DID they make light bulb work ? Bulb Installed in 1901 at the Livermore’s (CA) Fire station. C filament - 4 W ♦ Since 1800 the electric arc light was known. However, the life time of a filament made of carbon was poor. ♦ Since 1800 the electric arc light was known. However, the life time of a filament made of carbon was poor. ♦ The problem was in obtaining a high enough vacuum in the bulb and getting rid of the oxygen in the residual gas Use of the first Evaporable Getters Phosphorus pumped lamp tend to have a red cast

F. Le Pimpec 2 Choice of Getter – Vapor Pressure After Honig and Kramer (1969) When choosing a material to be used for a vacuum application. One question which need to be asked is : At Which temperature my system is going to be running ? The elements of your vacuum system must not limit the pressure you are aiming at. Their vapor pressure must be taken into account in the design. That is also true for your getter pump Al Mg Zn

F. Le Pimpec 3 Ti vs Other Getters in Accelerator A) Pumping Speed calculated at RT B) Wide variations due to film roughness C) For H 2, competition between desorption and diffusion inside the deposited layers Ref. “Sorption of Nitrogen by Titanium Films,” Harra and Hayward, Proc. Int. Symp. On Residual Gases in Electron Tubes, cm 2 Ref. “Le Normand CERN vacuum note” Ba - Ca - Mg : High vapor pressure. Trouble if bake out is requested Zr - Nb - Ta : Evaporation temperature too high Typical sublimation rate 0.1 to 0.5 g/hr 0.5 g/hr ; M Ti =48g/mol 0.5/(48*3600) = mol.s -1 1ML~10 15 atom.cm mol.s -1. Avogadro = atom.s -1 1 ms is necessary to evaporate 1 ML 3 minutes = 180E3 ms hence ML for 1cm 2

F. Le Pimpec 4 Also True for Thin Films TiZr and TiZrV V. Baglin et al.

F. Le Pimpec 5 Ionodesorption by heavy energetic ions on technical surfaces E. Mahner et al Pb 53+ ions (per shot) under 89.2° grazing incidence and 4.2 MeV/u

F. Le Pimpec 6 SEY & Electron Cloud SEY of technical surfaces baked at 350°C for 24hrs Electron cloud can exist in p + / e + beam accelerator and arise from a resonant condition (multipacting) between secondary electrons coming from the wall and the kick from the beam, (PEP II - KEK B - ISR - LHC). fast head-tail instability

F. Le Pimpec 7 SEY & Electron Cloud Hilleret et al. TiZrV coating 2 h at 300C, CO injected at NEG T=60C TiZrV coating Low SEY : Choice of the activating temperature and time of the NEG - or conditioning (e - photons ions) Contamination by gas exposure or by the vacuum residual gas increases the SEY Results vary from sample to sample Angles of incidence, of the PE, yield the shape of the curve toward higher values Roughness is an issue