Intensity Limits by Wakefields in Relativistic Dielectric Laser Acceleration Grating Structures

In Dielectric Laser Accelerators (DLAs) apertures are in submicrometer range. Intensity effects caused by wakefields are the critical limitations at relativistic energies. To estimate the intensity limits, we present simulations of longitudinal and transverse wakefields for different DLA grating geometries. These simulations enable to calculate the longitudinal beam loading limit. Additionally, coherent transverse beam stabilities are analyzed. Based on these studies, we estimate the influence of wakes on DLA experiments at 3 GeV planned at SwissFEL at the Paul Scherrer Institute (PSI). However, most models of transverse instabilities are valid only for linearized wakes, which holds at most in a fraction of the aperture. To take this into account, we outline the integration of a nonlinear wake kick in our simplified 6D particle tracking code DLAtrack6D. For verification, we compare both the linear and nonlinear tracking results to full Particle-In-Cell simulations.