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- S. Kato, M. Nishiwaki
KEK
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A copper chamber without coating and TiN and diamond like carbon (DLC) coated aluminum chambers were installed to an arc section of the KEKB positron ring to make comparisons of electron cloud activity as well as total pressure and residual gas components during the beam operation under the same condition. Recently a DLC coated aluminum chamber with high surface roughness that was obtained with cost-effective simple abrasive of the large grain before the coating was installed in the same arc section and exposed to the electron cloud until the KEKB shutdown. The measured electron cloud activity in the DLC coated chamber with smooth surface showed half and one-sixth of those in the TiN coated chamber and the copper chamber, respectively at the operation of around 1·103 Ah. Much more reduction of the e-cloud activity owing to the DLC on the roughed chamber surface was found, that is ,a reduction of one-fifth and one-tenth, respectively, in comparison with the DLC on non-roughed chamber and the TiN coating on non-roughed chamber at around 1·103 Ah. Preparation of the DLC coated chamber, characteristics of the DLC and measurements including the residual gas observation will be also reported in detail.
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Slides
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