Electron cloud build-up in two-beam regions for HL-LHC, heat load and vacuum aspects

Electron cloud in particle accelerators is known to havea detrimental eect on the vacuum pressure and can causea large heat deposition on a vacuum chamber surface. In aparticle collider, in the presence of two beams in the samechamber, the build-up of the electron cloud becomes morecomplicated and the electron density cannot be simply scaledfrom the case of a single beam. The build-up process in thedevices with common chambers can be modeled by correctlyaccounting for the arrival times of the two beams, the beampositions and their sizes. Numerical studies were made toestimate the electron flux on the internal surfaces of twocommon chamber devices of the future High LuminosityLarge Hadron Collider: the triplet assemblies in the fourexperimental insertion regions and the injection protectionabsorber (TDIS). Dierent possible coating options in bothdevices were investigated aiming at a reduction of the elec-tron current and of the deposited heat load.