Electron Cloud Instabilities And Beam Induced Multipacting In The Lhc And In The Vlhc

Electron-cloud Instabilities and Beam-induced Multipacting in the LHC and in the VLHC.

In the beam pipe of the Large Hadron Collider (LHC), photoemission and secondary emission give rise to a quasi-stationary electron cloud, which is established after a few bunch passages. The response of this electron cloud to a transversely displaced bunch resembles a short-range wakefield and can cause a fast instability. In addition, beam-induced multipacting of the electrons may lead to an enhanced gas desorption and an associated pressure increase. In this paper the authors report preliminary simulation results of the electron-cloud build-up both in a dipole magnet and in a straight section of the LHC at top energy. The effective wakefield created by the electron cloud translates into an instability rise time of about 40 ms horizontally and 500 ms vertically. This rise time is not much larger than that of the resistive-wall instability at injection energy. Similar simulation studies show that the instability rise time for the proposed Very Large Hadron Collider (VLHC) is about 3--4 s in both transverse planes. The smaller growth rate in the VLHC, as compared with the LHC, is primarily due to the much lower bunch population.

Proceedings of the Advanced ICFA Beam Dynamics Workshop on Beam Dynamics Issues for E+e- Factories

Reviews Of Accelerator Science And Technology - Volume 7: Colliders

The idea of colliding two particle beams to fully exploit the energy of accelerated particles was first proposed by Rolf Wideröe, who in 1943 applied for a patent on the collider concept and was awarded the patent in 1953. The first three colliders — AdA in Italy, CBX in the US, and VEP-1 in the then Soviet Union — came to operation about 50 years ago in the mid-1960s. A number of other colliders followed.Over the past decades, colliders defined the energy frontier in particle physics. Different types of colliers — proton-proton, proton-antiproton, electron-positron, electron-proton, electron-ion and ion-ion colliders — have played complementary roles in fully mapping out the constituents and forces in the Standard Model (SM). We are now at a point where all predicted SM constituents of matter and forces have been found, and all the latest ones were found at colliders. Colliders also play a critical role in advancing beam physics, accelerator research and technology development. It is timely that RAST Volume 7 is dedicated to Colliders.