DESY, Hamburg
The nonlinearities of the RF fields and the dispersion sections can be corrected with a higher harmonic RF module. In this paper we present an analytical solution for nonlinearity correction up to the third order in a multistage bunch compression and acceleration system without collective effects. A more general solution for a system with collective effects (space charge, wakefields, CSR effects) is found by iterative tracking procedure based on this analytical result. We apply the developed formalism to study two stage bunch compression in FLASH and three stage bunch compression in the European XFEL. Different charges are considered. Analytical estimations of RF tolerances are given.
DESY, Hamburg
Linac-based X-ray-free-electron lasers require very short bunches of high- brightness electron beams with peak currents of the order of kilo-Amperes and energies of the order of 10GeV. Essential components of a typical drive linac are a laser driven photo injector, the accelerator and a bunch compression system. Non linear effects from external fields (f.i. rf curvature and higher order longitudinal dispersion) as well as self effects due to space charge, wakes and coherent synchrotron radiation have to be considered for machine design. These main components will be described in principle, the layout of some drive linacs will be discussed and the magnitude of higher order effects and of self effects will be estimated.
