Modelling of the transverse mode suppressor for dielectric wake-field accelerator

The wake fields in the dielectric waveguide with deflection-mode damping are calculated. In addition, numerical results are presented and compared with experiment. An interesting property of the structure is that the axisymmetric mode is unaffected by the lined wire boundary and all higher order modes can be damped very quickly (in a few cycles). This has important implications for the dielectric-based wakefield accelerator. By reducing the beam-beam deflection, one may use multiple drive bunches to enhance the axial acceleration wake field without severe accumulated transverse wake-field effects. A large number of bunches also means that the total charge in each bunch can be reduced, thus reducing the head-tail instabilities within the driving beam, although the head-tail instabilities can be controlled to a certain degree by alternating focusing and defocusing magnetic fields applied around the wake-field device.<>