Open Access Publications from the University of California

High efficiency, high brightness X-ray free electron laser pulses via fresh bunch self-seeding and undulator tapering

• Author(s): EMMA, CLAUDIO
Following the numerical and theoretical studies of tapered XFELs, the remainder of the work describes the first experimental demonstration of fresh bunch self seeding in an XFEL. With this scheme we are able to generate high power (50 GW) narrow bandwidth ($\delta \omega/\omega_0=8\times 10^{-5}$) short X-ray pulses ($\delta t<10$ fs), well suited for X-ray diffraction imaging experiments and nonlinear science applications. We compare the performance of the fresh bunch self-seeding scheme with the established methods of Self-Amplified Spontaneous Emission (SASE) and regular self-seeding, measuring a relative brightness increase of a factor of 12.5 and a factor of 2.4 respectively. The results are a promising step forward towards enabling TW-level X-ray FEL pulses in future XFEL light sources.