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

Abstract

Electron cloud in particle accelerators is known to have a detrimental effect on the vacuum pressure and can cause a large heat deposition on a vacuum chamber surface. In a particle collider, in the presence of two beams in the same chamber, the build-up of the electron cloud becomes more complicated and the electron density cannot be simply scaled from the case of a single beam. The build-up process in the devices with common chambers can be modeled by correctly accounting for the arrival times of the two beams, the beam positions and their sizes. Numerical studies were made to estimate the electron flux on the internal surfaces of two common chamber devices of the future High Luminosity Large Hadron Collider: the triplet assemblies in the four experimental insertion regions and the injection protection absorber (TDIS). Different possible coating options in both devices were investigated aiming at a reduction of the electron current and of the deposited heat load.