Theory and measurement of the electron cloud effect

Abstract

Photoelectrons produced through the interaction of synchrotron radiation and the vacuum chamber walls can be accelerated by a charged particle beam, acquiring sufficient energy to produce secondary electrons (SEs) in collisions with the walls. If the secondary-electron yield (SEY) coefficient of the wall material is greater than one, a runaway condition can develop. In addition to the SEY, the degree of amplification depends on the beam intensity and temporal distribution. As the electron cloud builds up along a train of stored bunches, a transverse perturbation of the head bunch can be communicated to trailing bunches in a wakefield-like interaction with the cloud. The electron cloud effect is especially of concern for the high-intensity PEP-II (SLAC) and KEK B-factories and at the Large Hadron Collider (LHC) at CERN. An initiative was undertaken at the Advanced Photon Source (APS) storage ring to characterize the electron cloud in order to provide realistic limits on critical input parameters in the models and improve their predictive capabilities. An intensive research program was undertaken at CERN to address key issues relating to the LHC. After giving an overview, the recent theoretical and experimental results from the APS and the other laboratories will be discussed.

Accelerator physics challenges in future linear colliders

“…Finally, because of the low beam emittances and high densities, novel instabilities such as the fast beam-ion instability [21] or electron cloud instabilities [22] are potential limitations. At this time, there is insufficient experience with these effects to fully understand their implications however it is expected that they will impose severe constraints on the vacuum system design.…”

The Effect of Air Exposure on SEY and Surface Composition of Laser Treated Copper Applied in Accelerators

“…The electron cloud is a key problem in particle accelerators, which can cause the degradation of beam quality and limit the performance of particle accelerators with high energy, high intensity, high luminosity and long beam lifetime [1][2][3][4][5][6][7][8]. The methods of mitigating electron cloud effect have been studied by many researchers from several organizations, such as CERN [9,10], STFC [11,12], NSRL [13], KEK [7,14], INFN [15], etc.…”

Experimental investigation about energy balance of electron emission from materials under electron impacts at low energy: application to silver, graphite and SiO2

“…Until nowadays, EE has been thoroughly studied for high incident electrons energy (E 0 > 100 eV) [1][2][3][4][5][6][7][8]. However it has infrequently been studied for E 0 < 100 eV, although this phenomenon has a determining impact on numerous applications such as RF hardware's to prevent multipactor effect [9], electron-cloud effect in particles accelerator [10] or on Hall thrusters (HT) plasma/wall interactions.…”