FEL2013 - List of Authors (Tiedtke, K.I.)

Paper	Title	Page
MOPSO57	Measurement of Wigner Distribution Function for Beam Characterization of FELs	92
	T. Mey, K. Mann, B. Schäfer LLG, Goettingen, Germany B. Keitel, S. Kreis, M. Kuhlmann, E. Plönjes, K.I. Tiedtke DESY, Hamburg, Germany
	Free-electron lasers deliver VUV and soft x-ray pulses with the highest brilliance available and high spatial coherence. Users of such facilities have high demands on phase and coherence properties of the beam, for instance when working with coherent diffractive imaging (CDI). To gain highly resolved spatial coherence information, we have performed a caustic scan at BL2 of FLASH using the ellipsoidal beam line focusing mirror and a movable XUV sensitive CCD detector. This measurement allows for retrieving the Wigner distribution function, being the two-dimensional Fourier transform of the mutual intensity of the beam. Computing the reconstruction on a four-dimensional grid, this yields the Wigner distribution which describes the beam propagation completely. Hence, we are able to provide comprehensive information about spatial coherence properties of the FLASH beam including the mutual coherence function and the global degree of coherence. Additionally, we derive the beam propagation parameters such as Rayleigh length, waist diameter and the beam quality factor M².

TUPSO81	Challenges for Detection of Highly Intense FEL Radiation: Photon Beam Diagnostics at FLASH1 and FLASH2	417
	K.I. Tiedtke, M. Braune, G. Brenner, S. Dziarzhytski, B. Faatz, J. Feldhaus, B. Keitel, M. Kuhlmann, H. Kühn, E. Plönjes, A.A. Sorokin, R. Treusch DESY, Hamburg, Germany
	In spite of the evident progress in the development of FEL facilities, the characterization of important FEL photon beam parameters during FEL-commissioning and user experiments is still a great challenge. In particular pulse-resolved photon beam characterization is essential for most user experiments, but the unique properties of FEL radiation properties such as extremely high peak powers and short pulse lengths makes the shot-to-shot monitoring of important parameters very difficult. Therefore, sophisticated concepts have been developed and used at FLASH in order to measure radiation pulse intensity, beam position and spectral as well as temporal distribution – always coping with the highly demanding requirements of user experiments as well as machine operation. Here, an overview on the photon diagnostic devices operating at FLASH and FLASH II will be presented, with emphasizes on the pulse resolving intensity and energy detectors based on photoionization of rare gases.

WEPSO50	FLASH2 Beamline and Phontondiagnostics Concepts	614
	E. Plönjes, B. Faatz, J. Feldhaus, M. Kuhlmann, K.I. Tiedtke, R. Treusch DESY, Hamburg, Germany
	The FLASH II project will upgrade the soft X-ray free electron laser FLASH at DESY into a multi-beamline FEL user facility with the addition of a second undulator line FLASH2. The present FLASH linear accelerator will drive both undulator lines and FLASH2 will be equipped with variable-gap undulators to be able to deliver two largely independent wavelengths to user endstations at FLASH1 and FLASH2 simultaneously. A new experimental hall will offer space for up to seven user endstations, some of which will be installed permanently. The beamline system will be set up to cover a wide wavelength range with up to three beamlines capable of delivering the 5th harmonic at 0.8 nm and a fundamental in the water window while others will cover the longer wavelengths of 6 - 40 nm and beyond. Photon diagnostics have been developed for many years at FLASH and are in routine operation. Online measurements of intensity, position, wavelength, wavefront, and pulse length are optimized as well as photon beam manipulation tools such as a gas absorber and filters. Civil construction and installations of FLASH II are on-going and first beam is expected for early 2014.

Paper

Title

Page

Measurement of Wigner Distribution Function for Beam Characterization of FELs

92

T. Mey, K. Mann, B. Schäfer
LLG, Goettingen, Germany
B. Keitel, S. Kreis, M. Kuhlmann, E. Plönjes, K.I. Tiedtke
DESY, Hamburg, Germany

Free-electron lasers deliver VUV and soft x-ray pulses with the highest brilliance available and high spatial coherence. Users of such facilities have high demands on phase and coherence properties of the beam, for instance when working with coherent diffractive imaging (CDI). To gain highly resolved spatial coherence information, we have performed a caustic scan at BL2 of FLASH using the ellipsoidal beam line focusing mirror and a movable XUV sensitive CCD detector. This measurement allows for retrieving the Wigner distribution function, being the two-dimensional Fourier transform of the mutual intensity of the beam. Computing the reconstruction on a four-dimensional grid, this yields the Wigner distribution which describes the beam propagation completely. Hence, we are able to provide comprehensive information about spatial coherence properties of the FLASH beam including the mutual coherence function and the global degree of coherence. Additionally, we derive the beam propagation parameters such as Rayleigh length, waist diameter and the beam quality factor M².

TUPSO81

Challenges for Detection of Highly Intense FEL Radiation: Photon Beam Diagnostics at FLASH1 and FLASH2

417

K.I. Tiedtke, M. Braune, G. Brenner, S. Dziarzhytski, B. Faatz, J. Feldhaus, B. Keitel, M. Kuhlmann, H. Kühn, E. Plönjes, A.A. Sorokin, R. Treusch
DESY, Hamburg, Germany

In spite of the evident progress in the development of FEL facilities, the characterization of important FEL photon beam parameters during FEL-commissioning and user experiments is still a great challenge. In particular pulse-resolved photon beam characterization is essential for most user experiments, but the unique properties of FEL radiation properties such as extremely high peak powers and short pulse lengths makes the shot-to-shot monitoring of important parameters very difficult. Therefore, sophisticated concepts have been developed and used at FLASH in order to measure radiation pulse intensity, beam position and spectral as well as temporal distribution – always coping with the highly demanding requirements of user experiments as well as machine operation. Here, an overview on the photon diagnostic devices operating at FLASH and FLASH II will be presented, with emphasizes on the pulse resolving intensity and energy detectors based on photoionization of rare gases.

WEPSO50

FLASH2 Beamline and Phontondiagnostics Concepts

614

E. Plönjes, B. Faatz, J. Feldhaus, M. Kuhlmann, K.I. Tiedtke, R. Treusch
DESY, Hamburg, Germany

The FLASH II project will upgrade the soft X-ray free electron laser FLASH at DESY into a multi-beamline FEL user facility with the addition of a second undulator line FLASH2. The present FLASH linear accelerator will drive both undulator lines and FLASH2 will be equipped with variable-gap undulators to be able to deliver two largely independent wavelengths to user endstations at FLASH1 and FLASH2 simultaneously. A new experimental hall will offer space for up to seven user endstations, some of which will be installed permanently. The beamline system will be set up to cover a wide wavelength range with up to three beamlines capable of delivering the 5th harmonic at 0.8 nm and a fundamental in the water window while others will cover the longer wavelengths of 6 - 40 nm and beyond. Photon diagnostics have been developed for many years at FLASH and are in routine operation. Online measurements of intensity, position, wavelength, wavefront, and pulse length are optimized as well as photon beam manipulation tools such as a gas absorber and filters. Civil construction and installations of FLASH II are on-going and first beam is expected for early 2014.