High gradient limits due to single bunch beam breakup in a collinear dielectric wakefield accelerator

Abstract

A study into the maximum acceleration gradient, E_{z}^{max}, in a collinear dielectric wakefield accelerator due to single bunch beam breakup (SBBU) is presented. The longitudinal wakefield is proportional to charge over radius squared (E_{z}∼Q/a^{2}) which implies small a is favorable for fixed Q. However, when the transverse wakefield (E_{⊥}∼Q/a^{3}) is also considered then the SBBU instability severely limits the charge that can pass through a long structure as required for a large transfer of energy from the drive bunch to the witness bunch and hence limits the sustained acceleration that can be obtained.