IBIC2013 - List of Keywords (FEL)

Paper	Title	Other Keywords	Page
MOPC04	Electron Beam Collimation for Slice Diagnostics and Generation of Femtosecond Soft X-Ray Pulses from a Free Electron Laser	emittance, electron, diagnostics, collimation	49
	S. Di Mitri, M. Bossi, D. Castronovo, I. Cudin, M. Ferianis, L. Fröhlich Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
	We present the experimental results of femtosecond slicing an ultra-relativistic, high brightness electron beam with a collimator. We demonstrate that the collimation process preserves the slice beam quality, in agreement with our theoretical expectations, and that the collimation is compatible with the operation of a linear accelerator. Thus, it turns out to be a more compact and cheaper solution for electron slice diagnostics than commonly used radiofrequency deflecting cavities and having minimal impact on the machine design. The collimated beam can also be used for the generation of stable femtosecond soft x-ray pulses of tunable duration from a free electron laser. S. Di Mitri et al., Phys. Rev. Special Topics - Accel. Beams 16, 042801 (2013).

MOPC22	A New High-Dynamic Range BPM for ELBE with Integrated Differential Current Monitor (DCM)	BPM, ELBE, electron, single-bunch	104
	A. Büchner, B. Lange HZDR, Dresden, Germany
	ELBE is a LINAC electron accelerator for small energies (12 to 50 MeV). It serves as a beam source for many quite different experiments. The recent ELBE upgrade allows electron beams with bunches in the range of single electrons to 1 nC. The maximum beam current is 1.6 mA CW and the repetition rates covering the range from one shot single bunch pulses to 26 MHz CW. The existing BPMs and especially the DCMs which are used for the Machine Protection System cannot handle this wide parameter range. To improve this situation the development of new BPMs / DCMs was necessary. The DCMs measure the difference of the beam current between two stripline sensors and produce an interlock for differences greater 10 microamps. The new BPM electronics system has been designed including the DCM functionality because both BPMs and DCMs use the same stripline sensor signals at 1.3 GHz.

MOPC33	Status of the Fiber Link Stabilization Units at FLASH	laser, electron, free-electron-laser, polarization	139
	F. Zummack, M.K. Czwalinna, M. Felber, T. Lamb, H. Schlarb, S. Schulz, C. Sydlo DESY, Hamburg, Germany S. Jabłoński Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland
	State-of-the-art X-ray photon science with modern free-electron lasers (FEL) like FLASH and the upcoming European X-ray Free-Electron Laser Facility (XFEL) requires timing with femtosecond accuracy. For this purpose a sophisticated pulsed optical synchronization system distributes precise timing via length-stabilized fiber links throughout the entire FEL. Stations to be synchronized comprise bunch arrival time monitors, RF stations and optical cross-correlators for external lasers. The different requirements of all those stations have to be met by one optical link-stabilization-unit (LSU) design, compensating drifts and jitter in the distribution system down to a fs-level. Five years of LSU operation at FLASH have led to numerous enhancements resulting in an elaborate system. This paper presents these enhancements, their impact on synchronization performance and the latest state of the LSUs.

TUAL2	Commissioning the New LCLS X-band Transverse Deflecting Cavity with Femtosecond Resolution	LCLS, undulator, electron, linac	308
	P. Krejcik, F.-J. Decker, Y. Ding, J.C. Frisch, Z. Huang, J.R. Lewandowski, H. Loos, J.L. Turner, J.W. Wang, M.-H. Wang, J.J. Welch SLAC, Menlo Park, California, USA C. Behrens DESY, Hamburg, Germany
	Funding: This work was supported by Department of Energy Contract No. DE-AC0276SF00515 The new X-band transverse deflecting cavity began operation in May 2013 and is installed downstream of the LCLS undulator. It is operated at the full 120 Hz beam rate without interfering with the normal FEL operation for the photon users. The deflected beam is observed on the electron beam dump profile monitor, which acts as an energy spectrometer in the vertical plane. We observe, on a pulse by pulse basis, the time resolved energy profile of the spent electron beam from the undulator. The structure is powered from a 50 MW X-band klystron, giving a 48 MV kick to the beam which yields a 1 fs rms time resolution on the screen. We have measured the longitudinal profile of the electron bunches both with the FEL operating and with the lasing suppressed, allowing reconstruction of both the longitudinal profile of the incoming electron beam and the time-resolved profile of the X-ray pulse generated in the FEL. We are immediately able to see whether the bunch is chirped and which parts of the bunch are lasing, giving us new insight into tuning the machine for peak performance. The performance of the system will be presented along with examples of measurements taken during LCLS operation.
	Slides TUAL2 [9.210 MB]

TUPC36	First Realization and Performance Study of a Single-Shot Longitudinal Bunch Profile Monitor Utilizing a Transverse Deflecting Structure	longitudinal, feedback, kicker, electron	456
	M. Yan, C. Behrens, C. Gerth, R. Kammering, A. Langner, F. Obier, V. Rybnikov DESY, Hamburg, Germany J. Wychowaniak TUL-DMCS, Łódź, Poland
	For the control and optimization of electron beam parameters at modern free-electron lasers (FEL), transverse deflecting structures (TDS) in combination with imaging screens have been widely used as robust longitudinal diagnostics with single-shot capability, high resolution and large dynamic range. At the free-electron laser in Hamburg (FLASH), a longitudinal bunch profile monitor utilizing a TDS has been realized. In combined use with a fast kicker magnet and an off-axis imaging screen, selection and measurement of a single bunch out of the bunch train with bunch spacing down to 1us can be achieved without affecting the remaining bunches which continue to generate FEL radiation during user operation. Technical obstacles have been overcome such as suppression of coherent transition radiation from the imaging screen, the continuous image acquisition and processing with the bunch train repetition rate of 10Hz. The monitor, which provides the longitudinal bunch profile and length, has been used routinely at FLASH. In this paper, we present the setup and operation of the longitudinal bunch profile monitor as well as the performance during user operation.

TUPF33	Electron Beam Diagnostics Using Radiation from a Free Electron Laser	electron, radiation, space-charge, plasma	593
	M. Arbel H.I.T., Holon, Israel A. Eichenbaum Ariel University Center of Samaria, Faculty of Engineering, Ariel, Israel
	In most devices based on a high energy electron beam, which used for electromagnetic radiation production, great efforts are focused on the electron beam quality improvement. This is the case in a Free-Electron Laser (FEL) where electron beam with a low normalized emittance is required. Thus, diagnostic tools are required to investigate e-beam properties, such as beam emittance, longitudinal space charge, energy spread and velocity spread. In this paper we present analysis of radiation measurements obtained from a pre-bunched e-beam FEL. The measurements were made for a wide range of frequencies and for beam currents from low currents to high currents, where space charge effects can not neglected. We apply a frequency domain formulation to analyze the measured radiation. The spectral signature of the radiation emission obtained from a pre-bunched e-beam can provide vital information on e-beam properties. We show that a rigorous analysis of the measured radiation, allows characterization of the e-beam parameters. This analysis can provide some insights to the development of e-beam accelerators and radiation sources devices and to help physicists interpreting radiated signals.

WEPC32	Past, Present and Future Aspects of Laser-Based Synchronization at FLASH	laser, electron, controls, DESY	753
	S. Schulz, M. Bousonville, M.K. Czwalinna, M. Felber, M. Heuer, T. Lamb, J.M. Müller, P. Peier, S. Ruzin, H. Schlarb, B. Steffen, C. Sydlo, F. Zummack DESY, Hamburg, Germany T. Kozak, P. Predki TUL-DMCS, Łódź, Poland A. Kuhl Uni HH, Hamburg, Germany
	Free-electron lasers, like FLASH and the upcoming European XFEL, are capable of producing XUV and X-ray pulses of a few femtoseconds duration. For time-resolved pump-probe experiments and the externally seeded operation mode it is crucial not only to stabilize the arrival time of the electron bunches, but also to achieve a synchronization accuracy of external lasers on the same timescale. This can only be realized with a laser-based synchronization infrastructure. At FLASH, a periodic femtosecond laser pulse train is transmitted over actively stabilized optical fibers to the critical subsystems. In this paper we report on the present status and performance of the system, as well as its imminent upgrades and new installations. These include the connection of FLASH2, electron bunch arrival time monitors for low charges, a new master laser pulse distribution scheme, all-optical synchronization of the pump-probe laser and arrival time measurements of the UV pulses on the e-gun photocathode. Along with the coming connection of the acceleration modules to the master laser and the switch of the low-level hardware to the uTCA platform, an outlook to improved feedback strategies is given.

WEPC38	Current Status of Development of Optical Synchronization System for PAL XFEL	XFEL, laser, feedback, LCLS	772
	C.-K. Min, I. Eom, H.-S. Kang, B.R. Park, S.J. Park PAL, Pohang, Kyungbuk, Republic of Korea K. Jung, J. Kim, J. Lim KAIST, Daejeon, Republic of Korea
	Optical synchronization system has been developed for higher quality PAL XFEL with low timing jitter since 2011. In last two years, laboratory test was successfully performed, and test in our accelerator environment is ongoing. In laboratory, we tested the synchronization of RF master oscillator and optical master oscillator, the stabilization of 610 m optical fiber link, and the remote optical-to-RF conversion. We report recent our development results and summarize on-going optical timing project.
	Poster WEPC38 [3.366 MB]

WEPF27	Coherent Ultraviolet Radiation Measurements of Laser Induced Bunching in a Seeded FEL	radiation, laser, bunching, electron	879
	M. Veronese, A. Abrami, E. Allaria, M. Ferianis, E. Ferrari, M. Trovò Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy F. Cianciosi ESRF, Grenoble, France
	Optimization of the bunching process in a seeded FEL like FERMI@Elettra is an important aspect for machine operation. In this paper we discuss about the power detection of coherent radiation in the UV range as a valuable method for optimizing the bunching induced by the seeding process on the electron beam. Experimental results obtained at FERMI@Elettra are presented here. Measurements of UV coherent transition and diffraction radiation have been used to quantify the bunching produced by the seed laser at lower laser harmonics. The dependence of the laser induced CUVTR signal on various parameters is experimentally studied. Future upgrades and possibilities for bunching measurements at shortest wavelengths are also discussed.

Paper

Title

Other Keywords

Page

Electron Beam Collimation for Slice Diagnostics and Generation of Femtosecond Soft X-Ray Pulses from a Free Electron Laser

emittance, electron, diagnostics, collimation

49

S. Di Mitri, M. Bossi, D. Castronovo, I. Cudin, M. Ferianis, L. Fröhlich
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy

We present the experimental results of femtosecond slicing an ultra-relativistic, high brightness electron beam with a collimator*. We demonstrate that the collimation process preserves the slice beam quality, in agreement with our theoretical expectations, and that the collimation is compatible with the operation of a linear accelerator. Thus, it turns out to be a more compact and cheaper solution for electron slice diagnostics than commonly used radiofrequency deflecting cavities and having minimal impact on the machine design. The collimated beam can also be used for the generation of stable femtosecond soft x-ray pulses of tunable duration from a free electron laser.
* S. Di Mitri et al., Phys. Rev. Special Topics - Accel. Beams 16, 042801 (2013).

MOPC22

A New High-Dynamic Range BPM for ELBE with Integrated Differential Current Monitor (DCM)

BPM, ELBE, electron, single-bunch

104

A. Büchner, B. Lange
HZDR, Dresden, Germany

ELBE is a LINAC electron accelerator for small energies (12 to 50 MeV). It serves as a beam source for many quite different experiments. The recent ELBE upgrade allows electron beams with bunches in the range of single electrons to 1 nC. The maximum beam current is 1.6 mA CW and the repetition rates covering the range from one shot single bunch pulses to 26 MHz CW. The existing BPMs and especially the DCMs which are used for the Machine Protection System cannot handle this wide parameter range. To improve this situation the development of new BPMs / DCMs was necessary. The DCMs measure the difference of the beam current between two stripline sensors and produce an interlock for differences greater 10 microamps. The new BPM electronics system has been designed including the DCM functionality because both BPMs and DCMs use the same stripline sensor signals at 1.3 GHz.

MOPC33

Status of the Fiber Link Stabilization Units at FLASH

laser, electron, free-electron-laser, polarization

139

F. Zummack, M.K. Czwalinna, M. Felber, T. Lamb, H. Schlarb, S. Schulz, C. Sydlo
DESY, Hamburg, Germany
S. Jabłoński
Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland

State-of-the-art X-ray photon science with modern free-electron lasers (FEL) like FLASH and the upcoming European X-ray Free-Electron Laser Facility (XFEL) requires timing with femtosecond accuracy. For this purpose a sophisticated pulsed optical synchronization system distributes precise timing via length-stabilized fiber links throughout the entire FEL. Stations to be synchronized comprise bunch arrival time monitors, RF stations and optical cross-correlators for external lasers. The different requirements of all those stations have to be met by one optical link-stabilization-unit (LSU) design, compensating drifts and jitter in the distribution system down to a fs-level. Five years of LSU operation at FLASH have led to numerous enhancements resulting in an elaborate system. This paper presents these enhancements, their impact on synchronization performance and the latest state of the LSUs.

TUAL2

Commissioning the New LCLS X-band Transverse Deflecting Cavity with Femtosecond Resolution

LCLS, undulator, electron, linac

308

P. Krejcik, F.-J. Decker, Y. Ding, J.C. Frisch, Z. Huang, J.R. Lewandowski, H. Loos, J.L. Turner, J.W. Wang, M.-H. Wang, J.J. Welch
SLAC, Menlo Park, California, USA
C. Behrens
DESY, Hamburg, Germany

Funding: This work was supported by Department of Energy Contract No. DE-AC0276SF00515
The new X-band transverse deflecting cavity began operation in May 2013 and is installed downstream of the LCLS undulator. It is operated at the full 120 Hz beam rate without interfering with the normal FEL operation for the photon users. The deflected beam is observed on the electron beam dump profile monitor, which acts as an energy spectrometer in the vertical plane. We observe, on a pulse by pulse basis, the time resolved energy profile of the spent electron beam from the undulator. The structure is powered from a 50 MW X-band klystron, giving a 48 MV kick to the beam which yields a 1 fs rms time resolution on the screen. We have measured the longitudinal profile of the electron bunches both with the FEL operating and with the lasing suppressed, allowing reconstruction of both the longitudinal profile of the incoming electron beam and the time-resolved profile of the X-ray pulse generated in the FEL. We are immediately able to see whether the bunch is chirped and which parts of the bunch are lasing, giving us new insight into tuning the machine for peak performance. The performance of the system will be presented along with examples of measurements taken during LCLS operation.

Slides TUAL2 [9.210 MB]

TUPC36

First Realization and Performance Study of a Single-Shot Longitudinal Bunch Profile Monitor Utilizing a Transverse Deflecting Structure

longitudinal, feedback, kicker, electron

456

M. Yan, C. Behrens, C. Gerth, R. Kammering, A. Langner, F. Obier, V. Rybnikov
DESY, Hamburg, Germany
J. Wychowaniak
TUL-DMCS, Łódź, Poland

For the control and optimization of electron beam parameters at modern free-electron lasers (FEL), transverse deflecting structures (TDS) in combination with imaging screens have been widely used as robust longitudinal diagnostics with single-shot capability, high resolution and large dynamic range. At the free-electron laser in Hamburg (FLASH), a longitudinal bunch profile monitor utilizing a TDS has been realized. In combined use with a fast kicker magnet and an off-axis imaging screen, selection and measurement of a single bunch out of the bunch train with bunch spacing down to 1us can be achieved without affecting the remaining bunches which continue to generate FEL radiation during user operation. Technical obstacles have been overcome such as suppression of coherent transition radiation from the imaging screen, the continuous image acquisition and processing with the bunch train repetition rate of 10Hz. The monitor, which provides the longitudinal bunch profile and length, has been used routinely at FLASH. In this paper, we present the setup and operation of the longitudinal bunch profile monitor as well as the performance during user operation.

TUPF33

Electron Beam Diagnostics Using Radiation from a Free Electron Laser

electron, radiation, space-charge, plasma

593

M. Arbel
H.I.T., Holon, Israel
A. Eichenbaum
Ariel University Center of Samaria, Faculty of Engineering, Ariel, Israel

In most devices based on a high energy electron beam, which used for electromagnetic radiation production, great efforts are focused on the electron beam quality improvement. This is the case in a Free-Electron Laser (FEL) where electron beam with a low normalized emittance is required. Thus, diagnostic tools are required to investigate e-beam properties, such as beam emittance, longitudinal space charge, energy spread and velocity spread. In this paper we present analysis of radiation measurements obtained from a pre-bunched e-beam FEL. The measurements were made for a wide range of frequencies and for beam currents from low currents to high currents, where space charge effects can not neglected. We apply a frequency domain formulation to analyze the measured radiation. The spectral signature of the radiation emission obtained from a pre-bunched e-beam can provide vital information on e-beam properties. We show that a rigorous analysis of the measured radiation, allows characterization of the e-beam parameters. This analysis can provide some insights to the development of e-beam accelerators and radiation sources devices and to help physicists interpreting radiated signals.

WEPC32

Past, Present and Future Aspects of Laser-Based Synchronization at FLASH

laser, electron, controls, DESY

753

S. Schulz, M. Bousonville, M.K. Czwalinna, M. Felber, M. Heuer, T. Lamb, J.M. Müller, P. Peier, S. Ruzin, H. Schlarb, B. Steffen, C. Sydlo, F. Zummack
DESY, Hamburg, Germany
T. Kozak, P. Predki
TUL-DMCS, Łódź, Poland
A. Kuhl
Uni HH, Hamburg, Germany

Free-electron lasers, like FLASH and the upcoming European XFEL, are capable of producing XUV and X-ray pulses of a few femtoseconds duration. For time-resolved pump-probe experiments and the externally seeded operation mode it is crucial not only to stabilize the arrival time of the electron bunches, but also to achieve a synchronization accuracy of external lasers on the same timescale. This can only be realized with a laser-based synchronization infrastructure. At FLASH, a periodic femtosecond laser pulse train is transmitted over actively stabilized optical fibers to the critical subsystems. In this paper we report on the present status and performance of the system, as well as its imminent upgrades and new installations. These include the connection of FLASH2, electron bunch arrival time monitors for low charges, a new master laser pulse distribution scheme, all-optical synchronization of the pump-probe laser and arrival time measurements of the UV pulses on the e-gun photocathode. Along with the coming connection of the acceleration modules to the master laser and the switch of the low-level hardware to the uTCA platform, an outlook to improved feedback strategies is given.

WEPC38

Current Status of Development of Optical Synchronization System for PAL XFEL

XFEL, laser, feedback, LCLS

772

C.-K. Min, I. Eom, H.-S. Kang, B.R. Park, S.J. Park
PAL, Pohang, Kyungbuk, Republic of Korea
K. Jung, J. Kim, J. Lim
KAIST, Daejeon, Republic of Korea

Optical synchronization system has been developed for higher quality PAL XFEL with low timing jitter since 2011. In last two years, laboratory test was successfully performed, and test in our accelerator environment is ongoing. In laboratory, we tested the synchronization of RF master oscillator and optical master oscillator, the stabilization of 610 m optical fiber link, and the remote optical-to-RF conversion. We report recent our development results and summarize on-going optical timing project.

Poster WEPC38 [3.366 MB]

WEPF27

Coherent Ultraviolet Radiation Measurements of Laser Induced Bunching in a Seeded FEL

radiation, laser, bunching, electron

879

M. Veronese, A. Abrami, E. Allaria, M. Ferianis, E. Ferrari, M. Trovò
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
F. Cianciosi
ESRF, Grenoble, France

Optimization of the bunching process in a seeded FEL like FERMI@Elettra is an important aspect for machine operation. In this paper we discuss about the power detection of coherent radiation in the UV range as a valuable method for optimizing the bunching induced by the seeding process on the electron beam. Experimental results obtained at FERMI@Elettra are presented here. Measurements of UV coherent transition and diffraction radiation have been used to quantify the bunching produced by the seed laser at lower laser harmonics. The dependence of the laser induced CUVTR signal on various parameters is experimentally studied. Future upgrades and possibilities for bunching measurements at shortest wavelengths are also discussed.