FEL2011 - List of Keywords (diagnostics)

Paper	Title	Other Keywords	Page
MOPC28	Fine Tuning of the K-parameter of Two Segments of the European XFEL Undulator Systems	undulator, radiation, electron, simulation	144
	Y. Li, J. Pflüger European XFEL GmbH, Hamburg, Germany E. Gluskin ANL, Argonne, USA N. Vinokurov BINP SB RAS, Novosibirsk, Russia
	For large and segmented undulator systems as needed for the European XFEL a non-destructive, in situ, radiation diagnostics method would strongly compliment e-beam diagnostics. If such method would allow to fine tune the K parameter of individual undulator segments with an accuracy set by the Pierce parameter ρ, which is on the order of 2~3×10^-4, this would provide a very helpful tool for FEL commissioning. This paper provides a first analysis of a strategy of tuning the K parameter of two adjacent undulator segments. The spontaneous, monochromatized, on axis intensity is analyzed as a function of the phase delay set by the phase shifter in between. It makes use of diagnostic equipment which will be available at the European XFEL anyway. First results are demonstrated and limitations will be discussed.

TUPA18	Considerations about Optics-Based Phase-Space Measurements at Linac-Based FEL Facilities	optics, quadrupole, lattice, emittance	231
	B. Beutner, E. Prat Paul Scherrer Institut, Villigen, Switzerland
	Transverse phase-space measurements are an essential issue for FEL facilities. After acceleration in the injector the energy is sufficiently high to bring the beam out of the space-charge dominated regime, thus optics based techniques are favored. The beam moments at a given point in the machine are fitted to beam size values downstream with different phase advances between the reconstruction and the measurement point. Two principle methods are possible. Beam sizes can be measured at different positions in the beam line keeping the lattice unchanged. The other possibility is to actively change quadrupoles and use only one screen. These two techniques are compared in this paper including monte-carlo studies on systematic errors using the SwissFEL Injector Test Facility as an example. On the other hand beam size measurements, which are done with OTR screens at SwissFEL Injector Test Facility, are critical for such measurements. An analysis of these images can be an issue, especially if the signal-to-noise is compromised for example by low bunch charges. This study on the phase-space measurement techniques will be completed by a discussion of the image post-processing procedures.

TUPA31	Transverse Phase-space Studies for the Electron Optics at the Direct XUV-seeding Experiment at FLASH (DESY)	undulator, electron, simulation, emittance	263
	S. Ackermann, V. Miltchev, J. Roßbach Uni HH, Hamburg, Germany
	Funding: BMBF under contract No. 05 ES7GU1 - DFG GrK 1355 - Joachim Herz Stiftung During the shutdown in 2009/2010 the Free-Electron Laser in Hamburg (FLASH) was upgraded with an experiment to study the high-gain-FEL amplification of a laser ‘‘seed'' from a high harmonic generation (HHG) source in the XUV wavelength range-sFLASH. For an optimal FEL-performance knowledge of the electron bunch transverse phase-space as well as control on the electron optics parameters is required. In this contribution the technical design, the present status and the commissioning results of the sFLASH diagnostic stations will be presented. The possible options for transverse phase space characterization will be discussed. An emphasis will be put on the error analysis and the tolerance estimations. Analysis of experimental data from both OTR-screens and wire scanners will be presented and discussed.

WEPA20	Designing a Pulse-resolved Photon Diagnostic System for Shanghai SXFEL	FEL, photon, laser, synchrotron	374
	Y.Q. Wu, J.H. Chen, J.N. Liu, R.Z. Tai, D. Wang, R. Wang, C.F. Xue, G.F. Zhao SINAP, Shanghai, People's Republic of China
	It is presented the design of photon diagnostic system for SSRF-XFEL, the X-ray Free Electron Laser facility in Shanghai Synchrotron Radiation Facility. The system mainly includes a diagnostic beamline with two branches and some diagnostic devices. In the direct passing branch, the intensity distribution of the spot is measured. A set of multi-slit plates are applied for measuring the spatial coherence of a single FEL pulse; In the deflecting branch, a high-resolution VLS-PGM type monochromator, with a simple manual adjusting system, is set up for detecting spectrum of single FEL pulse. The measuring range of wavelength is 45nm-3nm. A fast responding EUV CCD ensures a high pulse resolution to 100Hz.

WEPB14	Ultra-short Electron Bunch and X-ray Temporal Diagnostics with an X-band Transverse Deflector	FEL, electron, undulator, radiation	405
	C. Behrens DESY, Hamburg, Germany Y.T. Ding, P. Emma, J.C. Frisch, Z. Huang, P. Krejcik, H. Loos, M.-H. Wang SLAC, Menlo Park, California, USA
	The measurement of ultra-short electron bunches on the femtosecond time scale constitutes a very challenging problem. In X-ray free-electron laser facilities such as the Linac Coherent Light Source (LCLS), generation of sub-ten femtosecond X-ray pulses is possible, and some efforts have been put into both ultra-short electron and X-ray beam diagnostics. Here we propose a single-shot method using a transverse deflector (X-band) after the undulator to reconstruct both the electron bunch and X-ray temporal profiles. Simulation studies show that about 1 fs (rms) time resolution may be achievable in the LCLS and is applicable to a wide range of FEL wavelengths and pulse lengths. The jitter, resolution and other related issues will be discussed.

THPA25	Standard Electron Beam Diagnostics for the European XFEL	electron, cavity, undulator, dipole	527
	D. Lipka DESY, Hamburg, Germany
	The European XFEL under construction in Hamburg needs to control the electron beam parameters for reliable machine and FEL operation. Due to the flexible bunch pattern, a minimum bunch spacing of 222 ns and large beam charge range a high dynamic range of the monitors is necessary. Furthermore the high average beam power enforces an elaborated machine protection system. This paper presents an overview of the planned standard electron beam diagnostics. The status of the main systems is presented, as well as the results from prototype tests with beam at FLASH.

THPB16	Beam Profile Measurements Using a Fast Gated CCD Camera and a Scintillation Screen to Suppress COTR	electron, radiation, FEL, photon	590
	M. Yan Uni HH, Hamburg, Germany C. Behrens, C. Gerth, G. Kube, B. Schmidt, S. Wesch DESY, Hamburg, Germany
	For standard beam profile measurements of high-brightness electron beams using optical transition radiation (OTR) screens, coherence effects induced by microbunching instabilities render direct imaging of the beam impossible. A technique of using a scintillation screen with a fast gated CCD camera has been demonstrated to successfully suppress coherent OTR (COTR) in transverse beam diagnostics at FLASH. The fast gated CCD camera has been installed next to a standard CCD camera setup and images the same viewing screens. The results of transverse beam profile measurements under operating conditions without COTR are compared for both setups. The fast gated camera has also been employed for longitudinal bunch profile measurements with a transverse deflecting structure (TDS). Results obtained under operating conditions with COTR are compared to those from longitudinal phase space measurements in a dispersive arm, where no coherence effects have been observed so far. In this paper, we examine the performance of the fast gated CCD camera for beam profile measurements and present further studies on the use of scintillation screens for high-energy electron beam diagnostics.

FROA4	Response Matrix of Longitudinal Instrumentation in SwissFEL	laser, feedback, instrumentation, electron	652
	R. Ischebeck, B. Beutner, R. Kalt, P. Peier, S. Reiche, T. Schilcher, V. Schlott Paul Scherrer Institut, Villigen, Switzerland
	Several sources of jitter and drift affect the longitudinal phase space dynamics of SwissFEL. To evaluate how drifts can be identified and corrected through appropriate diagnostics and beam-based feedbacks, the response matrix of possible longitudinal diagnostics on laser and RF stability is modeled. To this intent, photocathode laser intensity, laser arrival time, RF phases and RF amplitudes are individually varied in an ELEGANT model, and the expected response of on-line diagnostics on the simulated bunches is evaluated. By comparing the slope of the response to the expected resolution of the instrumentation, suitable monitors can be selected for a feedback.
	Slides FROA4 [2.837 MB]

Paper

Title

Other Keywords

Page

MOPC28

Fine Tuning of the K-parameter of Two Segments of the European XFEL Undulator Systems

undulator, radiation, electron, simulation

144

Y. Li, J. Pflüger
European XFEL GmbH, Hamburg, Germany
E. Gluskin
ANL, Argonne, USA
N. Vinokurov
BINP SB RAS, Novosibirsk, Russia

For large and segmented undulator systems as needed for the European XFEL a non-destructive, in situ, radiation diagnostics method would strongly compliment e-beam diagnostics. If such method would allow to fine tune the K parameter of individual undulator segments with an accuracy set by the Pierce parameter ρ, which is on the order of 2~3×10^-4, this would provide a very helpful tool for FEL commissioning. This paper provides a first analysis of a strategy of tuning the K parameter of two adjacent undulator segments. The spontaneous, monochromatized, on axis intensity is analyzed as a function of the phase delay set by the phase shifter in between. It makes use of diagnostic equipment which will be available at the European XFEL anyway. First results are demonstrated and limitations will be discussed.

TUPA18

Considerations about Optics-Based Phase-Space Measurements at Linac-Based FEL Facilities

optics, quadrupole, lattice, emittance

231

B. Beutner, E. Prat
Paul Scherrer Institut, Villigen, Switzerland

Transverse phase-space measurements are an essential issue for FEL facilities. After acceleration in the injector the energy is sufficiently high to bring the beam out of the space-charge dominated regime, thus optics based techniques are favored. The beam moments at a given point in the machine are fitted to beam size values downstream with different phase advances between the reconstruction and the measurement point. Two principle methods are possible. Beam sizes can be measured at different positions in the beam line keeping the lattice unchanged. The other possibility is to actively change quadrupoles and use only one screen. These two techniques are compared in this paper including monte-carlo studies on systematic errors using the SwissFEL Injector Test Facility as an example. On the other hand beam size measurements, which are done with OTR screens at SwissFEL Injector Test Facility, are critical for such measurements. An analysis of these images can be an issue, especially if the signal-to-noise is compromised for example by low bunch charges. This study on the phase-space measurement techniques will be completed by a discussion of the image post-processing procedures.

TUPA31

Transverse Phase-space Studies for the Electron Optics at the Direct XUV-seeding Experiment at FLASH (DESY)

undulator, electron, simulation, emittance

263

S. Ackermann, V. Miltchev, J. Roßbach
Uni HH, Hamburg, Germany

Funding: BMBF under contract No. 05 ES7GU1 - DFG GrK 1355 - Joachim Herz Stiftung
During the shutdown in 2009/2010 the Free-Electron Laser in Hamburg (FLASH) was upgraded with an experiment to study the high-gain-FEL amplification of a laser ‘‘seed'' from a high harmonic generation (HHG) source in the XUV wavelength range-sFLASH. For an optimal FEL-performance knowledge of the electron bunch transverse phase-space as well as control on the electron optics parameters is required. In this contribution the technical design, the present status and the commissioning results of the sFLASH diagnostic stations will be presented. The possible options for transverse phase space characterization will be discussed. An emphasis will be put on the error analysis and the tolerance estimations. Analysis of experimental data from both OTR-screens and wire scanners will be presented and discussed.

WEPA20

Designing a Pulse-resolved Photon Diagnostic System for Shanghai SXFEL

FEL, photon, laser, synchrotron

374

Y.Q. Wu, J.H. Chen, J.N. Liu, R.Z. Tai, D. Wang, R. Wang, C.F. Xue, G.F. Zhao
SINAP, Shanghai, People's Republic of China

It is presented the design of photon diagnostic system for SSRF-XFEL, the X-ray Free Electron Laser facility in Shanghai Synchrotron Radiation Facility. The system mainly includes a diagnostic beamline with two branches and some diagnostic devices. In the direct passing branch, the intensity distribution of the spot is measured. A set of multi-slit plates are applied for measuring the spatial coherence of a single FEL pulse; In the deflecting branch, a high-resolution VLS-PGM type monochromator, with a simple manual adjusting system, is set up for detecting spectrum of single FEL pulse. The measuring range of wavelength is 45nm-3nm. A fast responding EUV CCD ensures a high pulse resolution to 100Hz.

WEPB14

Ultra-short Electron Bunch and X-ray Temporal Diagnostics with an X-band Transverse Deflector

FEL, electron, undulator, radiation

405

C. Behrens
DESY, Hamburg, Germany
Y.T. Ding, P. Emma, J.C. Frisch, Z. Huang, P. Krejcik, H. Loos, M.-H. Wang
SLAC, Menlo Park, California, USA

The measurement of ultra-short electron bunches on the femtosecond time scale constitutes a very challenging problem. In X-ray free-electron laser facilities such as the Linac Coherent Light Source (LCLS), generation of sub-ten femtosecond X-ray pulses is possible, and some efforts have been put into both ultra-short electron and X-ray beam diagnostics. Here we propose a single-shot method using a transverse deflector (X-band) after the undulator to reconstruct both the electron bunch and X-ray temporal profiles. Simulation studies show that about 1 fs (rms) time resolution may be achievable in the LCLS and is applicable to a wide range of FEL wavelengths and pulse lengths. The jitter, resolution and other related issues will be discussed.

THPA25

Standard Electron Beam Diagnostics for the European XFEL

electron, cavity, undulator, dipole

527

D. Lipka
DESY, Hamburg, Germany

The European XFEL under construction in Hamburg needs to control the electron beam parameters for reliable machine and FEL operation. Due to the flexible bunch pattern, a minimum bunch spacing of 222 ns and large beam charge range a high dynamic range of the monitors is necessary. Furthermore the high average beam power enforces an elaborated machine protection system. This paper presents an overview of the planned standard electron beam diagnostics. The status of the main systems is presented, as well as the results from prototype tests with beam at FLASH.

THPB16

Beam Profile Measurements Using a Fast Gated CCD Camera and a Scintillation Screen to Suppress COTR

electron, radiation, FEL, photon

590

M. Yan
Uni HH, Hamburg, Germany
C. Behrens, C. Gerth, G. Kube, B. Schmidt, S. Wesch
DESY, Hamburg, Germany

For standard beam profile measurements of high-brightness electron beams using optical transition radiation (OTR) screens, coherence effects induced by microbunching instabilities render direct imaging of the beam impossible. A technique of using a scintillation screen with a fast gated CCD camera has been demonstrated to successfully suppress coherent OTR (COTR) in transverse beam diagnostics at FLASH. The fast gated CCD camera has been installed next to a standard CCD camera setup and images the same viewing screens. The results of transverse beam profile measurements under operating conditions without COTR are compared for both setups. The fast gated camera has also been employed for longitudinal bunch profile measurements with a transverse deflecting structure (TDS). Results obtained under operating conditions with COTR are compared to those from longitudinal phase space measurements in a dispersive arm, where no coherence effects have been observed so far. In this paper, we examine the performance of the fast gated CCD camera for beam profile measurements and present further studies on the use of scintillation screens for high-energy electron beam diagnostics.

FROA4

Response Matrix of Longitudinal Instrumentation in SwissFEL

laser, feedback, instrumentation, electron

652

R. Ischebeck, B. Beutner, R. Kalt, P. Peier, S. Reiche, T. Schilcher, V. Schlott
Paul Scherrer Institut, Villigen, Switzerland

Several sources of jitter and drift affect the longitudinal phase space dynamics of SwissFEL. To evaluate how drifts can be identified and corrected through appropriate diagnostics and beam-based feedbacks, the response matrix of possible longitudinal diagnostics on laser and RF stability is modeled. To this intent, photocathode laser intensity, laser arrival time, RF phases and RF amplitudes are individually varied in an ELEGANT model, and the expected response of on-line diagnostics on the simulated bunches is evaluated. By comparing the slope of the response to the expected resolution of the instrumentation, suitable monitors can be selected for a feedback.

Slides FROA4 [2.837 MB]