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AKBP: Arbeitskreis Beschleunigerphysik

AKBP 16: Posters

AKBP 16.13: Poster

Donnerstag, 19. März 2020, 16:30–18:00, P1C

Modelling of thermal and elastic response of x-ray optics exposed to high peak power fel pulses — •Roman Shayduk, Alexey Zozulya, Ilia Petrov, and Markus Scholz — European XFEL GmbH Holzkoppel 4 22869 Schenefeld Germany

The European X-ray Free-Electron Laser delivers femtoseconds-long pulses in soft and hard X-ray wavelength range with up to 2 mJ pulse energy. The pulses are arranged into pulse trains containing from 1 to several hundreds of pulses spaced down to 220 ns apart. Trains arrive at 10 Hz rate. Stochastic nature of Self-Amplified Spontaneous Emission (SASE) defines rather short ~0.2 fs coherence time of pulses due to the broad spectral band width. Many experimental techniques require longer temporal coherence, so monochromators are currently used to reduce the spectral bandwidth. However, due to the combination of ultra high peak power and high repetition rate of X-ray pulses the impulsive heat load becomes a real challenge for preserving the performance parameters of monochromators as the number of pulses per train grows.

We propose a unified model for simulating thermoelastic response of solid targets to fs/ps/ns pulsed electromagnetic radiation in the visible and hard X-ray range and apply it for the case of impulsive X-ray excitation of monochromator crystals. Calculations show that the heat induced strain relaxation time exceeds by far the pulse repetition period of 220 ns and the amplitude of strain exceeds the Darwin width of a crystal reflection multiple times.