• A. Hershcovitch, M. Blaskiewicz, J.M. Brennan, W. Fischer, C.J. Liaw, W. Meng
  BNL, Upton, Long Island, New York
• A.X. Custer, M.Y. Erickson, N.Z. Jamshidi, H.J. Poole
  PVI, Oxnard
• N. Sochugov
  Institute of High Current Electronics, Tomsk

Elec­tron clouds, which can limit ma­chine per­for­mance, have been ob­served in many ac­cel­er­a­tors in­clud­ing RHIC at BNL. They can be sup­pressed by low sec­ondary elec­tron yield beam pipe sur­faces. Ad­di­tion­al con­cern for the RHIC ma­chine, whose vac­u­um cham­ber is made from rel­a­tive­ly high re­sis­tiv­i­ty 316LN stain­less steel, is high wall re­sis­tiv­i­ty that can re­sult in un­ac­cept­ably high ohmic heat­ing for su­per­con­duct­ing mag­nets. The high re­sis­tiv­i­ty can be ad­dressed with a cop­per (Cu) coat­ing; a re­duc­tion in the sec­ondary elec­tron yield can be achieved with a TiN or amor­phous car­bon (a-C) coat­ing. Ap­ply­ing such coat­ings in an al­ready con­struct­ed ma­chine is rather chal­leng­ing. We start­ed de­vel­op­ing a robot­ic plas­ma de­po­si­tion tech­nique for in-situ coat­ing of long, small di­am­e­ter tubes. The tech­nique en­tails fab­ri­cat­ing a de­vice com­pris­ing of staged mag­netrons mount­ed on a mo­bile mole for de­po­si­tion of about 5 μm (a few skin depths) of Cu fol­lowed by about 0.1 μm of a-C. As a first step, a 15-cm Cu cath­ode mag­netron is being de­signed and fab­ri­cat­ed, after which, 30-cm long sam­ple of the RHIC pipe are to be Cu coat­ed. De­po­si­tion rates and af­fects on RF re­sis­tiv­i­ty are to be mea­sured.