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How DID they make light bulb work ?

How DID they make light bulb work ?. ♦ 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.

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How DID they make light bulb work ?

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  1. How DID they make light bulb work ? ♦ 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 Bulb Installed in 1901 at the Livermore’s (CA)Fire station. C filament - 4 W Phosphorus pumped lamp tend to have a red cast F. Le Pimpec

  2. Choice of Getter – Vapor Pressure 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 ? 1 Zn Mg Al 10-7 200 700 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 F. Le Pimpec After Honig and Kramer (1969)

  3. Ref. “Le Normand CERN vacuum note” Ref. “Sorption of Nitrogen by Titanium Films,” Harra and Hayward, Proc. Int. Symp. On Residual Gases in Electron Tubes, 1967 1cm2 Ti vs Other Getters in Accelerator 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 ; MTi =48g/mol 0.5/(48*3600) = 2.9 10-6 mol.s-1 1ML~1015 atom.cm-2 2.9 10-6 mol.s-1. Avogadro = 1.74 1018 atom.s-1 1 ms is necessary to evaporate 1 ML 3 minutes = 180E3 ms hence ML for 1cm2 A) Pumping Speed calculated at RT B) Wide variations due to film roughness C) For H2, competition between desorption and diffusion inside the deposited layers 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 1.5 109 Pb53+ ions (per shot) under 89.2° grazing incidence and 4.2 MeV/u E. Mahner et al. F. Le Pimpec

  6. fast head-tail instability SEY of technical surfaces baked at 350°C for 24hrs SEY & Electron Cloud 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). F. Le Pimpec

  7. TiZrV coating TiZrV coating 2 h at 300C, CO injected at NEG T=60C Hilleret et al. SEY & Electron Cloud Results vary from sample to sample Roughness is an issue 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 Angles of incidence, of the PE, yield the shape of the curve toward higher values F. Le Pimpec

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