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Parts handled for the “new” TDI BN blocks: Ti+Cu+NEG CuBe : NEG on blocks of spare TDI

Parts handled for the “new” TDI BN blocks: Ti+Cu+NEG CuBe : NEG on blocks of spare TDI Al: no coating Beamscreens : 4 coated with NEG . M.Taborelli for TE-VSC 18.3.2014. BN. BN after coating (Ti 5um+Cu 2um+NEG). BN after bake 300C (pressure up to 1e-3 mbar). Adhesion OK.

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Parts handled for the “new” TDI BN blocks: Ti+Cu+NEG CuBe : NEG on blocks of spare TDI

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  1. Parts handled for the “new” TDI • BN blocks: Ti+Cu+NEG • CuBe: NEG on blocks of spare TDI • Al: no coating • Beamscreens: 4 coated with NEG M.Taborelli for TE-VSC 18.3.2014

  2. BN BN after coating (Ti 5um+Cu 2um+NEG) BN after bake 300C (pressure up to 1e-3 mbar) Adhesion OK Probably too high pressure during bake-out and activation (outgassing from BN, 1E-3 mbar range ) gave peel off in spite of good results for the prototype Use old blocks (only Ti coated), rely on beam scrubbing for the SEY conditioning Strip the “new” series with CO2 jet (to be verified) -The NEG does not activate at all -no N or impurities -BN on the back face of delaminated NEG

  3. CuBe • Good adhesion after coating • Blocks baked in spare TDI: • Discolored on the coated face, local peel off (just faint grey on scotch tape) • Strong marks of oxidation on uncoated regions NEG face Cu side Use uncoated blocks and/or strip the coated ones: conditioning for SEY with beam scrubbing Note: the SEY is Cu2O is 1.3, as good as for clean metallic copper

  4. Al • Coating the Al blocs with NEG will produce the same problem and is not considered as safe • - 2 blocks in spare TDI are NEG coated, have dark colour (oxidized) but no peel off; one already stripped (was brought for cleaning) • - two further blocs coated in 2014 will be stripped not coated (from LHC) stripped , not coated Do a coating of the Al blocs with Ti: necessary to solve the e-cloud issue by relying on beam scrubbing

  5. Beamscreens • 4 units NEG coated, 4 units non-coated (StSt) • The same issue of peel off can occur due to the BN outgassing Strip the NEG from the 4, vacuum-fire and install all without coating

  6. proposal All modifications with respect to TDI1 will be implemented only if there will be sufficient time for extensive testing

  7. Example of pressure variation during full TDI tests (piece now in LHC) 10C/h – 300C for 48h

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