Chapter 12: Vacuum System

The luminosity upgrade programme (HL-LHC) requires modifications of the present LHC’s vacuum system, in particular in the triplets, crab cavities, matching section and experimental areas. Such modifications must follow guidelines similar to those followed for the present machine. The increased stored current implies a higher thermal power in the beam screen from the image current moving along with the stored particles and stronger synchrotron radiation (SR) and electron cloud (EC) effects, which in turn translate into higher degassing rates.