IBIC2019 - List of Keywords (free-electron-laser)

Paper	Title	Other Keywords	Page
TUPP002	Direct-Sampling Coarse Bunch Arrival Time Monitor in the Free Electron Laser FLASH Based on the Fast Digitizer Implemented in the FMC VITA 57.1 Standard	FEL, electron, pick-up, timing	275
	J. Zink, M.K. Czwalinna, M. Fenner, S. Jabłoński, J. Marjanovic, H. Schlarb DESY, Hamburg, Germany F. Gerfers Technische Universität Berlin, Berlin, Germany
	At the free-electron lasers FLASH and European-XFEL bunch arrival times are monitored with a high-accuracy electro-optical based data acquisition system (BAM). Due to only a couple of picoseconds time measurement range of this system, large timing changes might cause the monitor to fail. To remove any ambiguity and for health status monitoring a high-speed direct-sampling FPGA mezzanine card (FMC) and an analogue RF front-end was added. The circuitry has lower precision than the electro-optical based BAM, but it can determine bunch arrival time with respect to a reference signal over a large time range, i.e. of the order of 1 ms. After restarts or larger energy changes during operation, the electron bunch arrival time may have been changed by tens or even hundreds of picoseconds, which causes that the BAM is out of its operation range and needs to be recalibrated. With the solution developed, the BAM gets the coarse bunch timing from the digitizer and adjusts its optical delay lines accordingly. This allows for finding the operation point fast and automatically. Performance data of the fast direct-sampling digitizer FMC and first measurement data from FLASH will be presented.
	Poster TUPP002 [3.810 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-TUPP002
About •	paper received ※ 04 September 2019 paper accepted ※ 10 September 2019 issue date ※ 10 November 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPP011	Observation of Scintillators Charging Effects at the European XFEL	FEL, electron, diagnostics, operation	308
	A.I. Novokshonov, B. Beutner, G. Kube DESY, Hamburg, Germany S.A. Strokov TPU, Tomsk, Russia
	Scintillating screens are widely used for beam profile diagnostics at various kinds of particle accelerators. At modern linac based electron machines with ultrashort bunches as the European XFEL in Hamburg (Germany), scintillators help to overcome the limitation of standard OTR based monitors imposed by the emission of coherent radiation. The XFEL injector section is equipped with four off-axis screens allowing to perform online beam profile diagnostics, i.e. a single bunch out of a bunch train is kicked onto the screen and the profile is analyzed. However, during user operation a decrease of the SASE level was observed in cases that one of the of-axis screens was used. The observation is explained by charging of the scintillator screen: each deflected bunch hitting the screens causes ionization and charging of the screen. The scintillator as good insulator keeps the charge for some time such that the non-deflected part of the bunch-train feels their Coulomb force and experiences a kick, resulting in a drop of the SASE level. This report summarizes the observations at the European XFEL and introduces a simple model for quantification of this effect.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-TUPP011
About •	paper received ※ 04 September 2019 paper accepted ※ 07 September 2019 issue date ※ 10 November 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPP022	A Method of Correcting the Beam Transverse Offset for the Cavity Bunch Length Monitor	cavity, simulation, dipole, impedance	572
	Q. Wang, Q. Luo, B.G. Sun USTC/NSRL, Hefei, Anhui, People’s Republic of China
	Funding: Supported by National Key R&D Program of China (Grant No. 2016YFA0401900 and No. 2016YFA0401903) and The National Natural Science Foundation of China (Grant No. U1832169 and No. 11575181) Cavity bunch length monitor uses monopole modes excited by bunches within the cavities to measure the bunch longitudinal root mean square (rms) length. It can provide a very high accuracy and high resolution. However, when the bunch passes through the cavities with transverse offset (that is, the bunch moves off the cavity axis), the amplitude of the monopole modes will change and cannot reflect the bunch length precisely. In this paper, a method of correcting the beam transverse offset is proposed. Simulation results show that the method can reduce the error of the bunch length measurement significantly.
	Poster WEPP022 [0.735 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-WEPP022
About •	paper received ※ 03 September 2019 paper accepted ※ 10 September 2019 issue date ※ 10 November 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Other Keywords

Page

Direct-Sampling Coarse Bunch Arrival Time Monitor in the Free Electron Laser FLASH Based on the Fast Digitizer Implemented in the FMC VITA 57.1 Standard

FEL, electron, pick-up, timing

275

J. Zink, M.K. Czwalinna, M. Fenner, S. Jabłoński, J. Marjanovic, H. Schlarb
DESY, Hamburg, Germany
F. Gerfers
Technische Universität Berlin, Berlin, Germany

At the free-electron lasers FLASH and European-XFEL bunch arrival times are monitored with a high-accuracy electro-optical based data acquisition system (BAM). Due to only a couple of picoseconds time measurement range of this system, large timing changes might cause the monitor to fail. To remove any ambiguity and for health status monitoring a high-speed direct-sampling FPGA mezzanine card (FMC) and an analogue RF front-end was added. The circuitry has lower precision than the electro-optical based BAM, but it can determine bunch arrival time with respect to a reference signal over a large time range, i.e. of the order of 1 ms. After restarts or larger energy changes during operation, the electron bunch arrival time may have been changed by tens or even hundreds of picoseconds, which causes that the BAM is out of its operation range and needs to be recalibrated. With the solution developed, the BAM gets the coarse bunch timing from the digitizer and adjusts its optical delay lines accordingly. This allows for finding the operation point fast and automatically. Performance data of the fast direct-sampling digitizer FMC and first measurement data from FLASH will be presented.

Poster TUPP002 [3.810 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-TUPP002

About •

paper received ※ 04 September 2019 paper accepted ※ 10 September 2019 issue date ※ 10 November 2019

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPP011

Observation of Scintillators Charging Effects at the European XFEL

FEL, electron, diagnostics, operation

308

A.I. Novokshonov, B. Beutner, G. Kube
DESY, Hamburg, Germany
S.A. Strokov
TPU, Tomsk, Russia

Scintillating screens are widely used for beam profile diagnostics at various kinds of particle accelerators. At modern linac based electron machines with ultrashort bunches as the European XFEL in Hamburg (Germany), scintillators help to overcome the limitation of standard OTR based monitors imposed by the emission of coherent radiation. The XFEL injector section is equipped with four off-axis screens allowing to perform online beam profile diagnostics, i.e. a single bunch out of a bunch train is kicked onto the screen and the profile is analyzed. However, during user operation a decrease of the SASE level was observed in cases that one of the of-axis screens was used. The observation is explained by charging of the scintillator screen: each deflected bunch hitting the screens causes ionization and charging of the screen. The scintillator as good insulator keeps the charge for some time such that the non-deflected part of the bunch-train feels their Coulomb force and experiences a kick, resulting in a drop of the SASE level. This report summarizes the observations at the European XFEL and introduces a simple model for quantification of this effect.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-TUPP011

About •

paper received ※ 04 September 2019 paper accepted ※ 07 September 2019 issue date ※ 10 November 2019

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPP022

A Method of Correcting the Beam Transverse Offset for the Cavity Bunch Length Monitor

cavity, simulation, dipole, impedance

572

Q. Wang, Q. Luo, B.G. Sun
USTC/NSRL, Hefei, Anhui, People’s Republic of China

Funding: Supported by National Key R&D Program of China (Grant No. 2016YFA0401900 and No. 2016YFA0401903) and The National Natural Science Foundation of China (Grant No. U1832169 and No. 11575181)
Cavity bunch length monitor uses monopole modes excited by bunches within the cavities to measure the bunch longitudinal root mean square (rms) length. It can provide a very high accuracy and high resolution. However, when the bunch passes through the cavities with transverse offset (that is, the bunch moves off the cavity axis), the amplitude of the monopole modes will change and cannot reflect the bunch length precisely. In this paper, a method of correcting the beam transverse offset is proposed. Simulation results show that the method can reduce the error of the bunch length measurement significantly.

Poster WEPP022 [0.735 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-WEPP022

About •

paper received ※ 03 September 2019 paper accepted ※ 10 September 2019 issue date ※ 10 November 2019

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)