Development of a Sputtering Device for In Situ Coating of Long Beam Pipes of Particle Accelerators with a Low Secondary Electron Yield Carbon Thin Film
(Room Wabash 1)
11 May 16
10:00 AM
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10:20 AM
Tracks:
Emerging Technologies
In the framework of the ultimate upgrade of the Large Hadron Collider (LHC), named High Luminosity LHC (HL-LHC), some of the superconducting quadrupole magnets responsible for the final focusing of the proton beams before collision are expected to quench due to the total heat load resulting from the synchrotron radiation, the collision’s debris arising from the interaction point, and the electrons generated by multipacting in the beam pipe. A possible way to eradicate this last contribution is to coat the inner walls of the beam pipes with a carbon thin film having a maximal Secondary Electron Yield (SEY) of about 1, in order to supress the electron multipacting effect. In this work, we report on the development of coating devices, (based on sputtering), to deposit such a carbon layer in situ, i.e., without dismounting the quadrupole magnets from their operating positions in the LHC tunnel. Amongst the main constrains are the length of the magnet assemblies, (more than 30 meters), the aperture of the beam pipes, (down to 38 milimeters), the limited access to introduce the coating device, and the hydrogen partial pressure in the discharge during the deposition process. Different sputtering configurations are compared and the effect of the discharge gas (Ar) pressure and flow rate in the SEY and the deposition rate are investigated.