FEL2012 - List of Authors (Schmidt, B.)

Paper

Title

Page

Status of the FLASH II Project

381

K. Honkavaara, S. Ackermann, V. Ayvazyan, N. Baboi, V. Balandin, W. Decking, S. Düsterer, H.-J. Eckoldt, B. Faatz, M. Felber, J. Feldhaus, N. Golubeva, M. Körfer, M. Kuhlmann, T. Laarmann, A. Leuschner, L. Lilje, T. Limberg, N. Mildner, D. Nölle, F. Obier, A. Petrov, E. Plönjes, K. Rehlich, H. Remde, H. Schlarb, B. Schmidt, M. Schmitz, M. Scholz, S. Schreiber, H. Schulte-Schrepping, J. Spengler, M. Staack, N. Stojanovic, K.I. Tiedtke, M. Tischer, R. Treusch, M. Vogt, H.C. Weddig, T. Wohlenberg
DESY, Hamburg, Germany
M. Drescher, A. Hage, V. Miltchev, R. Riedel, J. Rönsch-Schulenburg, J. Roßbach, M. Schulz, A. Willner
Uni HH, Hamburg, Germany
F. Tavella
HIJ, Jena, Germany

The extension of the FLASH facility at DESY (Hamburg, Germany) - FLASH II Project - is under way. The extension includes a second undulator line with variable gap undulators to allow a more flexible operation, and a new experimental hall for photon experiments. The present FLASH linac will drive the both undulator beamlines. Civil construction of the new buildings has been started in autumn 2011 continuing in several steps until early 2013. The design of the new beamline including the extraction from the FLASH linac and the undulator is mostly finished, and the manufacturing of the components is under way. The mounting of the beamline will start in autumn 2012, and the commissioning with beam is scheduled for second half of 2013. We report here the design of the different phases of the project including the time schedule up to the first user operation.

WEPD54

Characterization of Single-cycle THz Pulses at the CTR Source at FLASH

500

S. Wunderlich, S. Schefer, B. Schmidt, S. Schulz, S. Wesch
DESY, Hamburg, Germany
M.C. Hoffmann
SLAC, Menlo Park, California, USA

At the coherent transition radiation source at the free-electron laser in Hamburg (FLASH) at DESY, single-cycle THz pulses with electric field strengths exceeding one MV/cm are generated. We present the temporal and spatial characterization of this source with the technique of electro-optic sampling using a laser system synchronized with the accelerator to better than 100 fs. This method offers a quantitative detection of the electric field of the THz pulses in the time domain. Compared to other electron-accelerator driven sources like undulator radiation, the transition radiation source provides pulses with a high bandwidth and durations shorter than one picosecond. This enables time-resolving and non-destructive experiments with radiation in the THz regime including THz pump / THz probe experiments. Broadband and intense THz pulses are expected to be valuable tools for the study of dynamics of excitation of complex materials in transient electric and magnetic fields.

THOC02

Determination of Temporal FEL Pulse Properties: Challenging Concepts and Experiments

N. Stojanovic, S. Düsterer, B. Schmidt, E. Schneidmiller, S. Schreiber, M.V. Yurkov
DESY, Hamburg, Germany
M. Drescher, W. Wurth
Uni HH, Hamburg, Germany
R. Mitzner
HZB, Berlin, Germany

Funding: BMBF, 05K10CHC
One of the most challenging tasks for the FEL photon diagnostics is the determination of the pulse duration - even more so information on the temporal substructure. The knowledge of the temporal pulse characteristics is important for wide range of experiments, from interaction of materials with high intensity radiation to ultrafast pump-probe studies. Here, the temporal resolution depends on the pulse duration as well as on the precise arrival time between the pump and probe pulse. Due to the wide range of available parameters at the existing and planned FELs, the photon energies are ranging from VUV to X-rays and pulse durations from sub fs up to 1ps range. Thus, a variety of methods has to be considered in order to characterize its temporal structure. Moreover due to the statistical nature of the SASE process, the pulse shape (consisting of multitude of sub-pulses) varies from shot to shot. Ultimately, single-shot pulse characterization is needed, which by far increases the level of complexity comparing to averaging techniques utilized so far. Here we present an overview of the different pulse diagnostics techniques that were utilized at FLASH in Hamburg.

THPD33

Generation of Ultra-short Electron Bunches at FLASH

610

J. Rönsch-Schulenburg, E. Hass, A. Kuhl, T. Plath, M. Rehders, J. Roßbach
Uni HH, Hamburg, Germany
A. Angelovski, R. Jakoby, A. Penirschke
TU Darmstadt, Darmstadt, Germany
N. Baboi, M. Bousonville, M.K. Czwalinna, C. Gerth, K. Klose, T. Limberg, U. Mavrič, H. Schlarb, B. Schmidt, S. Schreiber, B. Steffen, C. Sydlo, S. Vilcins, S. Wesch
DESY, Hamburg, Germany
S. Schnepp, T. Weiland
TEMF, TU Darmstadt, Darmstadt, Germany

Funding: The work is supported by German Federal Ministry of Education and Research (BMBF) within Joint Project - FSP 301 under the contract number 05K10GU2.
In order to produce radiation pulses of a few femtoseconds at FELs like FLASH, different concepts have been proposed. Probably the most robust method is to create an electron bunch, which is in the most extreme case as short as one longitudinal optical mode. For FLASH this translates into a bunch length of a few micrometers only. In order to mitigate space charge effects, the bunch charge needs to be about 20 pC. The technical requirements to achieve this goal are discussed. This includes beam dynamics studies to optimize the injection and compression of small charge electron bunches. A reduced photo injector laser pulse duration helps to relax the RF tolerance which scales linear with the compression factor. A new photo injector laser with sub-picosecond pulse duration in combination with a stretcher is used to optimize the initial bunch length. The commissioning of the new laser system and first experiments are described. Limitations of the presently available electron beam diagnostics at FLASH for short, low charge bunches are analyzed. Improvements of the longitudinal phase space diagnostics and the commissioning of a more sensitive beam arrival time monitor are described.

Paper	Title	Page
WEPD07	Status of the FLASH II Project	381
	K. Honkavaara, S. Ackermann, V. Ayvazyan, N. Baboi, V. Balandin, W. Decking, S. Düsterer, H.-J. Eckoldt, B. Faatz, M. Felber, J. Feldhaus, N. Golubeva, M. Körfer, M. Kuhlmann, T. Laarmann, A. Leuschner, L. Lilje, T. Limberg, N. Mildner, D. Nölle, F. Obier, A. Petrov, E. Plönjes, K. Rehlich, H. Remde, H. Schlarb, B. Schmidt, M. Schmitz, M. Scholz, S. Schreiber, H. Schulte-Schrepping, J. Spengler, M. Staack, N. Stojanovic, K.I. Tiedtke, M. Tischer, R. Treusch, M. Vogt, H.C. Weddig, T. Wohlenberg DESY, Hamburg, Germany M. Drescher, A. Hage, V. Miltchev, R. Riedel, J. Rönsch-Schulenburg, J. Roßbach, M. Schulz, A. Willner Uni HH, Hamburg, Germany F. Tavella HIJ, Jena, Germany
	The extension of the FLASH facility at DESY (Hamburg, Germany) - FLASH II Project - is under way. The extension includes a second undulator line with variable gap undulators to allow a more flexible operation, and a new experimental hall for photon experiments. The present FLASH linac will drive the both undulator beamlines. Civil construction of the new buildings has been started in autumn 2011 continuing in several steps until early 2013. The design of the new beamline including the extraction from the FLASH linac and the undulator is mostly finished, and the manufacturing of the components is under way. The mounting of the beamline will start in autumn 2012, and the commissioning with beam is scheduled for second half of 2013. We report here the design of the different phases of the project including the time schedule up to the first user operation.

WEPD54	Characterization of Single-cycle THz Pulses at the CTR Source at FLASH	500
	S. Wunderlich, S. Schefer, B. Schmidt, S. Schulz, S. Wesch DESY, Hamburg, Germany M.C. Hoffmann SLAC, Menlo Park, California, USA
	At the coherent transition radiation source at the free-electron laser in Hamburg (FLASH) at DESY, single-cycle THz pulses with electric field strengths exceeding one MV/cm are generated. We present the temporal and spatial characterization of this source with the technique of electro-optic sampling using a laser system synchronized with the accelerator to better than 100 fs. This method offers a quantitative detection of the electric field of the THz pulses in the time domain. Compared to other electron-accelerator driven sources like undulator radiation, the transition radiation source provides pulses with a high bandwidth and durations shorter than one picosecond. This enables time-resolving and non-destructive experiments with radiation in the THz regime including THz pump / THz probe experiments. Broadband and intense THz pulses are expected to be valuable tools for the study of dynamics of excitation of complex materials in transient electric and magnetic fields.

THOC02	Determination of Temporal FEL Pulse Properties: Challenging Concepts and Experiments
	N. Stojanovic, S. Düsterer, B. Schmidt, E. Schneidmiller, S. Schreiber, M.V. Yurkov DESY, Hamburg, Germany M. Drescher, W. Wurth Uni HH, Hamburg, Germany R. Mitzner HZB, Berlin, Germany
	Funding: BMBF, 05K10CHC One of the most challenging tasks for the FEL photon diagnostics is the determination of the pulse duration - even more so information on the temporal substructure. The knowledge of the temporal pulse characteristics is important for wide range of experiments, from interaction of materials with high intensity radiation to ultrafast pump-probe studies. Here, the temporal resolution depends on the pulse duration as well as on the precise arrival time between the pump and probe pulse. Due to the wide range of available parameters at the existing and planned FELs, the photon energies are ranging from VUV to X-rays and pulse durations from sub fs up to 1ps range. Thus, a variety of methods has to be considered in order to characterize its temporal structure. Moreover due to the statistical nature of the SASE process, the pulse shape (consisting of multitude of sub-pulses) varies from shot to shot. Ultimately, single-shot pulse characterization is needed, which by far increases the level of complexity comparing to averaging techniques utilized so far. Here we present an overview of the different pulse diagnostics techniques that were utilized at FLASH in Hamburg.

THPD33	Generation of Ultra-short Electron Bunches at FLASH	610
	J. Rönsch-Schulenburg, E. Hass, A. Kuhl, T. Plath, M. Rehders, J. Roßbach Uni HH, Hamburg, Germany A. Angelovski, R. Jakoby, A. Penirschke TU Darmstadt, Darmstadt, Germany N. Baboi, M. Bousonville, M.K. Czwalinna, C. Gerth, K. Klose, T. Limberg, U. Mavrič, H. Schlarb, B. Schmidt, S. Schreiber, B. Steffen, C. Sydlo, S. Vilcins, S. Wesch DESY, Hamburg, Germany S. Schnepp, T. Weiland TEMF, TU Darmstadt, Darmstadt, Germany
	Funding: The work is supported by German Federal Ministry of Education and Research (BMBF) within Joint Project - FSP 301 under the contract number 05K10GU2. In order to produce radiation pulses of a few femtoseconds at FELs like FLASH, different concepts have been proposed. Probably the most robust method is to create an electron bunch, which is in the most extreme case as short as one longitudinal optical mode. For FLASH this translates into a bunch length of a few micrometers only. In order to mitigate space charge effects, the bunch charge needs to be about 20 pC. The technical requirements to achieve this goal are discussed. This includes beam dynamics studies to optimize the injection and compression of small charge electron bunches. A reduced photo injector laser pulse duration helps to relax the RF tolerance which scales linear with the compression factor. A new photo injector laser with sub-picosecond pulse duration in combination with a stretcher is used to optimize the initial bunch length. The commissioning of the new laser system and first experiments are described. Limitations of the presently available electron beam diagnostics at FLASH for short, low charge bunches are analyzed. Improvements of the longitudinal phase space diagnostics and the commissioning of a more sensitive beam arrival time monitor are described.