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Progress report on coatings for SPSU. Aging of a-C/Zr Degassing for various coating parameters Next liners in SPS Conditioning with electrons A different solution for the magnet coating. S.Calatroni, P.Chiggiato, P.Costa Pinto, M.Taborelli, I.Wevers, C.Yin Vallgren Special Guest: G.Rumolo.
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Progress report on coatings for SPSU Aging of a-C/Zr Degassing for various coating parameters Next liners in SPS Conditioning with electrons A different solution for the magnet coating S.Calatroni, P.Chiggiato, P.Costa Pinto, M.Taborelli, I.Wevers, C.Yin Vallgren Special Guest: G.Rumolo
Improvement with a-C on rough coatings a-C/Zr -advantage: low SEY, less sensitive to aging -disadvantage: it requires 2 subsequent coatings
Degassing rate for different parameters Measured after 1h air exposure and 10h pumping a-C(Ar) a-C(Ne) SEY=1 SEY=1 SEY=1.02 SEY=0.99 1.08 -less porous at low pressure? -effect of bombardment by higher energy neutrals?
Strip detectors in magnets: changes during shutdown Present situation -XSD1: liner with StSt reference -XSD2: liner with a-C (CNe13) -SDneg:liner with NEG -EcEx: electron repeller • Next: • New StSt for reference • Same + long venting • New a-C • Rough a-C/Zr • a-C sample in the SPS-SEY sample position NB: 1) electron repeller should be redesigned; if the new version is ready it will be inserted in EcEx instead of the liner 2) If the aperture in the remaining C-magnet is sufficiently large either the repeller or the additional liner will be put there
Magnet coating -preliminary coating tests with B-field parallel to E-field show low efficiency of deposition: a different voltage configuration on the cathodes will be used to get a component EB Coating of test magnet: -most of the parts from the workshop are ready, ordered UHV components almost ready (Turbo pump, valves) -waiting to displace the magnet in 181(re-arrangement due to repair of the LHC quads), rebuilding the fence around the installation: before end of the year Insertion in SPS of coated magnets: -see presentation of J.Bauche -symmetric configuration of 2 un-coated+2 coated magnets and RF diagnostics -at least 2 magnets to be ready for week 8-11
Conditioning with electrons Electrons at 500eV, relative SEY measured directly with the irradiation gun, at 500eV by polarizing the sample +/-45V
A different solution for the magnet coating -insert a coated sheet of metal (gutter-like) fixed to the bottom of the chamber (as spot welded…). Corresponds to a half- coated chamber -the advantages would be that: -it can be exchanged -coating is easier for logistics (not on site!) and parameter optimization -calculation of G.Rumolo for the necessary SEY and in future for the necessary width
E-cloud density for half-coated +half uncoated (δmax=1.8) pipe G.Rumolo