BNL, Upton, Long Island, New York, USA
Wakefields in high-current ERLs can cause significant beam quality degradations. Here we summarize effects of Coherent Synchrotron Radiation (CSR), resistive wall, accelerator cavities and wall roughness for ERL parameters of the eRHIC project. A possibility of compensation of such correlated energy spread is presented. An emphasis in the discussion is made on CSR suppression due to shielding and on the suppression of wall roughness effects for realistic surfaces.
BNL, Upton, Long Island, New York, USA
Treatment of Coulomb collisions within the beam requires consideration of both large and small angle scattering. The effect when particles can be lost as a result of a single collision event (large-angle scattering) is called Touschek effect. When the scattering angles are small, random addition of such small scattering events leads to diffusion which primarily changes beam dimensions. Such a multiple Coulomb scattering is called Intrabeam Scattering (IBS). It is important to distinguish the Touschek effect and IBS. The Touschek effect describes particle loss as a result of single collision, where only transfer from transverse into longitudinal direction plays a role. It is important to consider this effect for design of high-current ERL to have an appropriate choice of collimation system. IBS results in changes of beam distribution and does not necessarily lead to a beam loss. Evaluation of IBS in ERL, where beam distribution is non-Gaussian (especially in the longitudinal phase-space), requires special treatment. Here we describe IBS and its treatment with application to ERL. The Touschek effect in ERL is also discussed.