Single beam collective effects in the LHC

Single-beam collective effects can limit the current and therefore the performance of the Large Hadron Collider (LHC), unless the impedance of the different vacuum chamber discontinuities seen by the beam is kept below certain limits.Together with parasitic loss considerations, this has an impact on the design of several machine components, such as monitors, kickers, bellows, warm sections, experimental beam pipes, rf-cavities, feedback systems and especially on the thermal beam screen, with its millions of pumping slots.After reviewing the LHC impedance budget in view of the most recent design options, we compute rise times and thresholds for different instabilities, as well as coherent and incoherent tune shifts and parasitic losses.