Günter Brenner

A non-invasive online photoionization spectrometer for FLASH2

A description of the design of an instrument for FEL wavelength monitoring based on photoionization of rare gases is given, as well as a report on calibration and characterization studies.

FLASH free-electron laser single-shot temporal diagnostic: terahertz-field-driven streaking

The installation and commissioning of a pulse length diagnostic setup at FLASH based on terahertz streaking is reported.

CAMP@FLASH: an end-station for imaging, electron- and ion-spectroscopy, and pump–probe experiments at the FLASH free-electron laser

Beamline BL1 at the FLASH free-electron laser facility at DESY was upgraded with new transport and focusing optics for the installation of the new permanent CAMP end-station, a multi-purpose instrument optimized for electron- and ion-spectroscopy, imaging and pump–probe experiments. An overview of the layout, beam transport, focusing capabilities, and experimental possibilities of this new end-station, as well as results from its commissioning and first experiments, are presented.

Free-electron laser multiplex driven by a superconducting linear accelerator.

Free-electron lasers (FELs) generate femtosecond XUV and X-ray pulses at peak powers in the gigawatt range. The FEL user facility FLASH at DESY (Hamburg, Germany) is driven by a superconducting linear accelerator with up to 8000 pulses per second. Since 2014, two parallel undulator beamlines, FLASH1 and FLASH2, have been in operation. In addition to the main undulator, the FLASH1 beamline is equipped with an undulator section, sFLASH, dedicated to research and development of fully coherent extreme ultraviolet photon pulses using external seed lasers. In this contribution, the first simultaneous lasing of the three FELs at 13.4 nm, 20 nm and 38.8 nm is presented.

Quasi-real-time photon pulse duration measurement by analysis of FEL radiation spectra

Considering the second-order spectral correlation function of SASE-FEL radiation allows a real-time observation of the photon pulse duration during spectra acquisition.

Double-grating monochromatic beamline with ultrafast response for FLASH2 at DESY

The preliminary design of a monochromatic beamline for FLASH2 at DESY is discussed.

Grating monochromator with ultrafast response for FLASH2 at DESY

We discuss the design of grating-based monochromators for coherent ultrafast pulses in the extreme-ultraviolet. The main application of such instruments is the monochromatization of ultrafast high-order laser harmonics and freeelectron-laser pulses. We present the conditions to be fulfilled by a grating monochromator that doesn’t increase the pulse duration significantly longer than the Fourier limit. A full correction of the pulse-front tilt requires the use of two gratings in a time-delay compensating configuration. The grating-monochromator configuration is applied to the design of the monochromatic beamline for FLASH2 at DESY. The monochromator has to be tunable in the 50-1000 eV energy range with a resolving power higher than 1000 and an instrumental response shorter than 100 fs in the whole energy range. Given the actual parameters of the FLASH2 radiation and the restrictions in the positioning of the optical elements, the tilt of the pulse-front given by a single grating would give an unacceptable temporal stretching of the pulse. This has to be corrected by a second grating in the compensated configuration. The residual distortion of the pulse-front after the second grating is well below 10 fs.

Operation of Free Electron Laser FLASH Driven by Short Electron Pulses

The program of low charge mode of operation is under development at free electron laser FLASH aiming in single mode radiation pulses. A short pulse photoinjector laser has been installed at FLASH allowing production of ultrashort electron pluses with moderate compression factor of the beam formation system. Here we present pilot results of free electron laser FLASH operating at the wavelength λ = 13.1 nm and driven by 70 pC electron bunches. Relevant theoretical analysis has been performed showing good agreement with experimental results.