BNL, Upton, Long Island, New York, USA
PVI, Oxnard, California, USA
To alleviate the problems of unacceptable ohmic heating and of electron clouds, a 50 cm long cathode magnetron mole was fabricated and successfully operated to copper coat an assembly containing a full-size stainless steel cold bore RHIC magnet tubing connected to two types of RHIC bellows, to which two additional RHIC tubing pipes were connected. To increase cathode lifetime, movable magnet package was developed, and thickest possible cathode was made, with rather challenging target to substrate distance of less than 1.5 cm. The magnetron is mounted on a carriage with spring loaded wheels that successfully crossed bellows and adjusted for variations in vacuum tube diameter, while keeping the magnetron centered. Electrical power and cooling water are fed through a motorized spool driven umbilical cabling system, which is enclosed in a flexible braided metal sleeve. Optimized process to ensure excellent adhesion was developed. Coating adhesion of 10 μm Cu surpassed all industrial tests; exceeded maximum capability of a 12 kg pull test fixture. Details of experimental setup for coating two types of bellows and a full-scale magnet tube sandwiched between them will be presented.
BNL, Upton, Long Island, New York, USA
PVI, Oxnard, California, USA
An in-situ technique for coating stainless steel vacuum tubes with Cu was developed to mitigate the problems of wall resistivity that leads to unacceptable ohmic heating of superconducting magnets cold bore and electron cloud generation in RHIC that can limit future machine luminosity enhancement. Room temperature RF resistivity of 10 μm Cu coated stainless steel RHIC beam tube has conductivity close to copper tubing. Before coating the RHIC beam pipe with copper, it is imperative to test the Cu coating’s conductivity at cryogenic. A folded quarter wave resonator structure has been designed and built for insertion in a cryogenic system to measure RF resistivity of copper coated RHIC tubing at liquid helium temperatures. The design is based on making the resonator structure out of a superconducting material such that the copper coating is the most lossy material. RHIC tubing samples prepared with different magnetron sputtering deposition modes are to be optimized by iterative processes. Additionally, this device can also be used for the development of better, cheaper SRF cavities and electron guns. The apparatus and its design details will be presented.