Numerical propagation simulations and coherence analysis of SASE wavefronts

Examples of wavefront propagation simulation and coherence analysis of Self-Amplified Spontaneous Emission (SASE), seeded and started-up from noise, are presented. The calculations are performed using SRW-the wave-optics computer code optimized for Synchrotron Radiation (SR), and the 3D FEL simulation code GENESIS. To ensure easy inter-operation and data exchange between the two codes, GENESIS has been integrated into the "emission" part of the SRW, which is dedicated for calculation of initial wavefronts in the form ready for subsequent propagation simulations. After each run of GENESIS in time-dependent mode, the resulting electric field is transformed from time to frequency domain, and the wavefront obtained this way is numerically propagated, using Fourier-optics methods implemented in SRW, from the exit of FEL undulator to a destination plane of a beamline containing several optical elements separated by drift spaces. Interferometer-type optical schemes, which allow for "probing" spatial and temporal coherence of SASE wavefronts, are used in the examples. Intensity distributions of the propagated radiation are extracted and analysed in time and frequency domains. The presented examples show that the SRW code can be used for optimization of optical beam lines for 4 generation synchrotron radiation sources, which require accurate treatment of wave-optical phenomena in frequency and time domains.