FEL2012 - Table of Session: TUOB (XFELs)

Paper

Title

Page

Spectral Characterization of the FERMI Pulses in the Presence of Electron-beam Phase-space Modulations

213

E. Allaria, S. Di Mitri, W.M. Fawley, E. Ferrari, L. Fröhlich, L. Giannessi, B. Mahieu, G. Penco, C. Spezzani, M. Trovò
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
G. De Ninno, S. Spampinati
University of Nova Gorica, Nova Gorica, Slovenia

As a seeded FEL based on a single stage HGHG configuration, FERMI's FEL-1 has produced very narrow bandwidth FEL pulses in the XUV wavelength region relative to those typical of SASE devices. This important feature of seeded FELs relies however upon the capability to produce high quality electron beams and with clean longitudinal phase spaces. As has been predicted previously, the FEL output spectra can be modified from a simple, nearly transform-limited single spike by modulation and distortions of the longitudinal phase space of the electron beam. In this work we report a study of the FEL spectra recorded at FERMI for various situations showing the effects of phase-space modulation on the FEL properties.

Slides TUOB02 [4.376 MB]

TUOB03

Complete Ultrafast X-ray Pulse Characterization at FELs

A.L. Cavalieri, H. Bromberger, I. Grguras, S. Huber
CFEL, Hamburg, Germany
C. Behrens, S. Düsterer, H. Schlarb
DESY, Hamburg, Germany
C. Bostedt, J.D. Bozek, R.N. Coffee, Y.T. Ding, J.B. Hastings, M.C. Hoffmann, S. Schorb
SLAC, Menlo Park, California, USA
J.T. Costello
DCU, Dublin, Republic of Ireland
L.F. DiMauro
Ohio State University, USA
G. Doumy
ANL, Argonne, USA
W. Helml, R. Kienberger, A.R. Maier, W. Schweinberger
MPQ, Garching, Munich, Germany
N.M. Kabachnik, T. Mazza, M. Meyer, T. Tschentscher
XFEL. EU, Hamburg, Germany
A.K. Kazansky
UPV-EHU, Leioa, Spain

The ability to fully characterize X-ray pulses from free electron-lasers will underpin their exploitation in experiments ranging from single-molecule imaging to extreme timescale X-ray science. This issue is especially acute when confronted with the characteristics of current generation FELs operating on the principle of SASE, as most parameters fluctuate strongly from pulse to pulse. Here, we have extended the techniques of attosecond metrology with the use of single-cycle terahertz (THz) pulses, allowing for simultaneous, in-line, single-shot measurement of both the arrival time and temporal profile of FEL pulses on an absolute scale. The technique is non-invasive and could be incorporated in pump-probe experiments, eventually leading to characterization before and after interaction with most sample environments. Optical-laser-driven THz streaking measurements, revealing X-ray pulse structure shorter than 50 fs FWHM in the soft X-ray regime at FLASH and in the ~ keV range at LCLS will be discussed. With clear potential for improvement in resolution to the sub-10 fs regime, this method will ultimately allow for characterization of the shortest predicted few-femtosecond FEL pulses.

Slides TUOB03 [15.857 MB]

TUOB04

Comparison of Hard X-Ray Self-seeding with SASE after a Monochromator at LCLS

217

J.J. Welch, F.-J. Decker, J.B. Hastings, Z. Huang, A.A. Lutman, M. Messerschmidt, J.L. Turner
SLAC, Menlo Park, California, USA

Funding: ** Work supported in part by the DOE Contract DE-AC02-76SF00515.
Self-seeding of a hard x-ray FEL was demonstrated at LCLS in January 2012 and produced a factor of 40-50 bandwidth reduction using a electron bunch charge of 20-40 pC*. For many hard x-ray users, the photon intensity after a monochromator is an important performance parameter. In this paper, we report results from a subsequent study of self-seeding performance using the Si (111) K-monochromator with a full bandwidth of 1.2 eV at 8.2 keV. These include a direct comparison of the average intensity of the monochromatized seeded beam with that of a monochromatized fully tuned-up SASE beam, in both cases using 150 pC bunch charge. The intensity distribution, fluctuations, and spatial profiles of the monochromatized radiation are studied and compared.
* J. Amann, et. al, Nature Photonics, to be published

Slides TUOB04 [1.417 MB]

Paper	Title	Page
TUOB02	Spectral Characterization of the FERMI Pulses in the Presence of Electron-beam Phase-space Modulations	213
	E. Allaria, S. Di Mitri, W.M. Fawley, E. Ferrari, L. Fröhlich, L. Giannessi, B. Mahieu, G. Penco, C. Spezzani, M. Trovò Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy G. De Ninno, S. Spampinati University of Nova Gorica, Nova Gorica, Slovenia
	As a seeded FEL based on a single stage HGHG configuration, FERMI's FEL-1 has produced very narrow bandwidth FEL pulses in the XUV wavelength region relative to those typical of SASE devices. This important feature of seeded FELs relies however upon the capability to produce high quality electron beams and with clean longitudinal phase spaces. As has been predicted previously, the FEL output spectra can be modified from a simple, nearly transform-limited single spike by modulation and distortions of the longitudinal phase space of the electron beam. In this work we report a study of the FEL spectra recorded at FERMI for various situations showing the effects of phase-space modulation on the FEL properties.
	Slides TUOB02 [4.376 MB]

TUOB03	Complete Ultrafast X-ray Pulse Characterization at FELs
	A.L. Cavalieri, H. Bromberger, I. Grguras, S. Huber CFEL, Hamburg, Germany C. Behrens, S. Düsterer, H. Schlarb DESY, Hamburg, Germany C. Bostedt, J.D. Bozek, R.N. Coffee, Y.T. Ding, J.B. Hastings, M.C. Hoffmann, S. Schorb SLAC, Menlo Park, California, USA J.T. Costello DCU, Dublin, Republic of Ireland L.F. DiMauro Ohio State University, USA G. Doumy ANL, Argonne, USA W. Helml, R. Kienberger, A.R. Maier, W. Schweinberger MPQ, Garching, Munich, Germany N.M. Kabachnik, T. Mazza, M. Meyer, T. Tschentscher XFEL. EU, Hamburg, Germany A.K. Kazansky UPV-EHU, Leioa, Spain
	The ability to fully characterize X-ray pulses from free electron-lasers will underpin their exploitation in experiments ranging from single-molecule imaging to extreme timescale X-ray science. This issue is especially acute when confronted with the characteristics of current generation FELs operating on the principle of SASE, as most parameters fluctuate strongly from pulse to pulse. Here, we have extended the techniques of attosecond metrology with the use of single-cycle terahertz (THz) pulses, allowing for simultaneous, in-line, single-shot measurement of both the arrival time and temporal profile of FEL pulses on an absolute scale. The technique is non-invasive and could be incorporated in pump-probe experiments, eventually leading to characterization before and after interaction with most sample environments. Optical-laser-driven THz streaking measurements, revealing X-ray pulse structure shorter than 50 fs FWHM in the soft X-ray regime at FLASH and in the ~ keV range at LCLS will be discussed. With clear potential for improvement in resolution to the sub-10 fs regime, this method will ultimately allow for characterization of the shortest predicted few-femtosecond FEL pulses.
	Slides TUOB03 [15.857 MB]

TUOB04	Comparison of Hard X-Ray Self-seeding with SASE after a Monochromator at LCLS	217
	J.J. Welch, F.-J. Decker, J.B. Hastings, Z. Huang, A.A. Lutman, M. Messerschmidt, J.L. Turner SLAC, Menlo Park, California, USA
	Funding: ** Work supported in part by the DOE Contract DE-AC02-76SF00515. Self-seeding of a hard x-ray FEL was demonstrated at LCLS in January 2012 and produced a factor of 40-50 bandwidth reduction using a electron bunch charge of 20-40 pC. For many hard x-ray users, the photon intensity after a monochromator is an important performance parameter. In this paper, we report results from a subsequent study of self-seeding performance using the Si (111) K-monochromator with a full bandwidth of 1.2 eV at 8.2 keV. These include a direct comparison of the average intensity of the monochromatized seeded beam with that of a monochromatized fully tuned-up SASE beam, in both cases using 150 pC bunch charge. The intensity distribution, fluctuations, and spatial profiles of the monochromatized radiation are studied and compared. J. Amann, et. al, Nature Photonics, to be published
	Slides TUOB04 [1.417 MB]