Keyword: FEL
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MOOB03 Upgrade and Status of Standard Diagnostic-Systems at FLASH and FLASHForward electron, diagnostics, electronics, cavity 13
 
  • N. Baboi, H.T. Duhme, O. Hensler, G. Kube, T. Lensch, D. Lipka, B. Lorbeer, Re. Neumann, P.A. Smirnov, T. Wamsat, M. Werner
    DESY, Hamburg, Germany
 
  Electron beam diagnostics plays a crucial role in the precise and reliable generation of ultra-short high bril-liance XUV and soft X-ray beams at the Free Electron Laser in Hamburg (FLASH). Most diagnostic systems monitor each of up to typically 600 bunches per beam, with a frequency of up to 1 MHz, a typical charge be-tween 0.1 and 1 nC and an energy of 350 to 1250 MeV. The diagnostic monitors have recently undergone a major upgrade. This process started several years ago with the development of monitors fulfilling the requirements of the European XFEL and of the FLASH2 undulator beamline and it continued with their installation and commissioning. Later they have been further improved and an upgrade was made in the old part of the linac. Also the FLASHForward plasma-wakefield acceleration experiment has been installed in the third beamline. This paper will give an overview of the upgrade of the BPM, Toroid and BLM systems, pointing out to their improved performance. Other systems underwent a partial upgrade, mainly by having their VME-based ADCs replaced with MTCA type. The overall status of the diagnostic will be reviewed.  
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-MOOB03  
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MOOC03 The Removal of Interference Noise of ICT using the PCA Method SRF, experiment, electron, Windows 22
 
  • J. Chen, Y.B. Leng, L.Y. Yu
    SINAP, Shanghai, People's Republic of China
  • N. Zhang
    SSRF, Shanghai, People's Republic of China
 
  The measurement of beam charge is a fundamental re-quirement to all particle accelerators facility. Shanghai soft X-ray free-electron laser (SXFEL) started construc-tion in 2015 and is now in the commission phase. Al-though integrated current transformer (ICT) were installed in the entire FEL for the measurement of the absolute beam charge, the accurate measurement becomes difficult in the injector and the main accelerator section due to the noise interference from external factors such as klystron modulator. The evaluation of the source of noise signals and the procession of noise reduction using the principal component analysis (PCA) are proposed in this paper. Experiment results show that PCA method can effectively remove the interference of lower frequency noise from the klystron modulator and it can also improve the resolution of the ICT system. Detailed experiment results and data analysis will be mentioned as well.  
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-MOOC03  
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MOPB10 A Study on the Influence of Bunch Longitudinal Distribution on the Cavity Bunch Length Measurement cavity, electron, free-electron-laser, laser 97
 
  • Q. Wang, Q. Luo, B.G. Sun, F.F. Wu
    USTC/NSRL, Hefei, Anhui, People's Republic of China
 
  Funding: Supported by National Key R&D Program of China (2016YFA0401900, 2016YFA0401903), NSFC (11375178, 11575181) and the Fundamental Research Funds for the Central Universities (WK2310000046)
Cavity bunch length measurement is used to obtain the bunch length depending on the eigenmodes exciting in-side the cavity. For today's FELs, the longitudinal distribution of particles in electron bunch (bunch shape) may be non-Gaussian, sometimes very novel. In this paper, the influence of bunch shape on the cavity bunch length measurement is analyzed, and some examples are given to verify the theoretical results. The analysis shows that the longitudinal distribution of particles in electron bunch has little influence on the cavity bunch length measure-ment when the bunch length is less than 1 ps and the eigenmodes used in measurement are below 10GHz.
 
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MOPC11 Data Acquisition System for Beam Instrumentation of SXFEL and DCLS controls, laser, data-acquisition, instrumentation 137
 
  • Y.B. Yan
    SINAP, Shanghai, People's Republic of China
  • J. Chen, L.W. Lai, Y.B. Leng, C.L. Yu, L.Y. Yu, H. Zhao, W.M. Zhou
    SSRF, Shanghai, People's Republic of China
 
  The high-gain free electron lasers have given scientists hopes for new scientific discoveries in many frontier research areas. The Shanghai X-Ray Free-Electron Laser (SXFEL) test facility is commissioning at the SSRF campus. The Dalian Coherent Light Source (DCLS) has successfully commissioned in the northeast of China, which is the brightest vacuum ultraviolet free electron laser facility. The data acquisition system for beam instrumentation is based on EPICS platform. The field programmable gate array (FPGA) and embedded controller are adopted for the signal processing and device control. The high-level applications are developed using Python. The details of the data acquisition system will be reported in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-MOPC11  
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MOPC16 The Development and Applications of Digital BPM Signal Processor on SSRF SRF, brilliance, controls, storage-ring 147
 
  • L.W. Lai, F.Z. Chen, Y.B. Leng, Y.B. Yan, N. Zhang, W.M. Zhou
    SSRF, Shanghai, People's Republic of China
 
  The development of Digital BPM Signal Processors (DBPM) for SSRF started from 2008. The first prototype for SSRF storage ring was completed in 2012, with turn-by-turn resolution better than 1μm. From 2016 to 2017, SSRF successively constructed two FEL facilities in China, DCLS and SXFEL test facilities. The second ver-sion DBPM was developed and used in large scale during this period to meet the requirements of signal processing for stripline BPMs and cavity BPMs. After that, we turned to the development of DBPM for SSRF storage ring based on the second version hardware, including FPGA firmware, EPICS IOC, EDM control panel. The development was completed and tests were carried out in early 2018. Test results showed that the position data is accurate and can monitor beam movement correctly, and online turn-by-turn position data resolution reaches 0.46μm. This paper will introduce the design of DBPM for the SSRF storage ring and the tests carried out to verify the data accuracy and evaluate the system performance.  
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-MOPC16  
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MOPC17 On-line Crosstalk Measurement and Compensation Algorithm Study of SXFEL Digital BPM System cavity, experiment, undulator, background 150
 
  • F.Z. Chen, L.W. Lai, Y.B. Leng, T. Wu, L.Y. Yu
    SSRF, Shanghai, People's Republic of China
  • J. Chen, R.X. Yuan
    SINAP, Shanghai, People's Republic of China
 
  Shanghai soft X-ray Free Electron Laser (SXFEL) has acquired the custom designed Digital BPM processor used for signal processing of cavity BPMs and stripline BPMs. In order to realize monitor the beam position accurately, it has high demand for DBPM system performance. Considering the crosstalk may introduce distortion and influence beam position resolution, it is important to analyze and compensate the crosstalk to improve the resolution. We choose the CBPM signal to study the crosstalk for its narrowband and sensitive for phase. The main experiment concept is successive accessing four channels to form a signal transfer matrix, which including amplitude frequency response and phase response information. And the compensation algorithm is acquire four channel readouts, then using the signal transfer matrix to reverse the true signal to ensure the accurate beam position measurement. This concept has already been tested at SXFEL and hopeful to compensate the crosstalk sufficiently.  
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TUOA01 The Diagnostic System at the European XFEL; Commissioning and First User Operation MMI, diagnostics, operation, electron 162
 
  • D. Nölle
    DESY, Hamburg, Germany
 
  The European XFEL is now commissioned and user operation has started. Long bunch trains up to 300 bunches are established. The role of and experience with the beam diagnostic will be reported. Highlights, problems and their solutions will be discussed.  
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TUPB05 Design of a Cavity Beam Position Monitor for the ARES Accelerator at DESY dipole, resonance, cavity, simulation 269
 
  • D. Lipka, M. Dohlus, M. Marx, S. Vilcins, M. Werner
    DESY, Hamburg, Germany
 
  The SINBAD facility (Short and INnovative Bunches and Accelerators at DESY) is foreseen to host various experiments in the field of production of ultra-short electron bunches and novel high gradient acceleration techniques. The SINBAD linac, also called ARES (Accelerator Research Experiment at SINBAD), will be a conventional S-band linear RF accelerator allowing the production of low charge (within a range between 0.5 pC and 1000 pC) ultra-short electron bunches. To detect the low charge bunches a cavity beam position monitor is designed based on the experience from the EU-XFEL. It will consist of a stainless steel body with low Q factor of 70, a resonance frequency of 3.3 GHz and a relative wide gap of 15 mm to reach a high peak position sensitivity of 4.25 V/(nC mm). The design considerations and simulation results will be presented.  
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TUPB09 The Evaluation of Beam Inclination Angle on the Cavity BPM Position Measurement cavity, simulation, experiment, electron 278
 
  • J. Chen, L.W. Lai, Y.B. Leng, L.Y. Yu, R.X. Yuan
    SINAP, Shanghai, People's Republic of China
 
  Cavity beam position monitor (CBPM) is widely used to measure the transverse position in free-electron laser (FEL) and international linear collider (ILC) facilities due to the characteristic of high sensitive. In order to study the limiting factors of the position resolution of cavity BPM, the influence of beam inclination angle on the measure-ment of CBPM position and the direction of beam deflec-tion was analyzed. The simulation results show that the beam inclination angle is an important factor limiting the superiority of CBPM with extremely high position resolu-tion. The relative beam experiments to change the relative inclination angle between the cavity and the electron beam based on a 4-dimension moveable platform were performed in Shanghai Soft X-ray FEL (SXFEL) facility, the experiment results will also be mentioned as well.  
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TUPC05 Influence of Sampling Rate and Passband on the Performance of Stripline BPM experiment, simulation, electron, data-acquisition 307
 
  • T. Wu, S.S. Cao, F.Z. Chen, Y.B. Leng, Y.M. Zhou
    SSRF, Shanghai, People's Republic of China
  • J. Chen, L.W. Lai
    SINAP, Shanghai, People's Republic of China
 
  It is obviously that the property of SBPM is influenced by data acquisition system, but how the procedure of data acquisition and processing takes effect is still room for enquiring into it. This paper will present some data simulation and experiment results to discuss the function between resolution and pass band, sampling rate or other influence factor. We hope that this paper would give some advice for building up data acquisition system of SBPM.  
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TUPC11 Design of an Ultrafast Stripline Kicker for Bunch-by-Bunch Feedback kicker, impedance, HOM, electron 322
 
  • J. Wang, P. Li, D. Wu, D.X. Xiao, L.G. Yan
    CAEP/IAE, Mianyang, Sichuan, People's Republic of China
 
  Funding: Work supported by China National Key Scientific Instrument and Equipment Development Project (2011YQ130018), National Natural Science Foundation of China (11475159, 11505173, 11575264 and 11605190)
The CAEP THz Free Electron Laser (CTFEL) will have a fast transverse bunch-by-bunch feedback system on its test beamline, which is used to correct the beam position differences of individual bunches with interval of about 2 ns. In this paper, we are proposing an ultrafast wideband stripline kicker, which is able to provide a kick to the bunch in a 2 ns time window. The structure design and simulation results of this kicker are also discussed.
 
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WEOA03 First Electro-Optical Bunch Length Measurements from the European XFEL laser, electron, optics, detector 338
 
  • B. Steffen, M.K. Czwalinna, C. Gerth, P. Peier
    DESY, Hamburg, Germany
 
  Three electro-optical bunch length detection systems based on spectral decoding have been installed and are being commissioned at the European XFEL. The systems are capable of recording individual longitudinal bunch profiles with sub-picosecond resolution at a bunch repetition rate 1.13 MHz. Bunch lengths and arrival times of entire bunch trains with single-bunch resolution have been measured as well as jitter and drifts for consecutive bunch trains. In this paper, we present first measurement results for the electro-optical detection system located after the second bunch compressor. A preliminary comparison with data from the bunch arrival-time monitor shows good agreement.  
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-WEOA03  
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WEOA04 The Application of Beam Arrival Time Measurement at SXFEL cavity, experiment, electron, laser 342
 
  • S.S. Cao, J. Chen, Y.B. Leng, R.X. Yuan
    SINAP, Shanghai, People's Republic of China
 
  Shanghai soft X-ray free electron laser (SXFEL) is able to generate high brightness and ultra-short light pulses. The generation of the light sources relies on the synchronization between seeded laser and electron bunch. Beam arrival time play an important role to keep the synchronization. For the SXFEL, a beam arrival time resolution under 100 fs is required. In this paper, the application of beam arrival time measurement scheme on SXFEL has been presented. The whole BAM system consists of four parts: beam arrival time monitor, electronic front-end, signal acquisition system, and high-level signal processing and presentation. Currently, four sets of beam arrival time monitors (BAMs) have been installed in the SXFEL and distributed in four different locations. The relevant beam arrival time experiment and beam flight time experiment based on the dual-cavities mixing method have also been performed so as to evaluate and analyze the beam status.  
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WEOB03 The European XFEL Beam Loss Monitor System electron, high-voltage, controls, undulator 357
 
  • T. Wamsat, T. Lensch
    DESY, Hamburg, Germany
 
  The European XFEL MTCA based Beam Loss Monitor System (BLM) is composed of about 470 monitors, which are part of the Machine Protection System (MPS). The BLMs detect losses of the electron beam, in order to protect accelerator components from damage and excessive activation, in particular the undulators, since they are made of permanent magnets. Also each cold accelerating module is equipped with a BLM to measure the sudden onset of field emission (dark current) in cavities. In addition some BLMs are used as detectors for wire- scanners. Experience from the already running BLM system in FLASH2 which is developed for XFEL and tested here, led to a fast implementation of the system in the XFEL. Further firmware and server developments related to alarm generation and handling are ongoing. The BLM systems structure, the current status and the different possibilities to trigger alarms which stop the electron beam will be presented.  
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WEOC03 A Simple Model to Describe Smoke Ring Shaped Beam Profile Measurements With Scintillating Screens at the European XFEL electron, diagnostics, scattering, ECR 366
 
  • G. Kube, S. Liu, A.I. Novokshonov, M. Scholz
    DESY, Hamburg, Germany
 
  Standard beam profile measurements of high-brightness electron beams based on OTR may be hampered by coherence effects. Therefore it was decided for the European XFEL to measure transverse beam profiles based on scintillating screen monitors using LYSO:Ce. While it is possible to resolve beam sizes down to a few micrometers with this scintillator, the experience during the XFEL commissioning showed that the measured emittance values were significantly larger than the expected ones. In addition, beam profiles measured at bunch charges of a few hundred pC showed a 'smoke ring' structure. While coherent OTR emission and beam dynamical influence can be excluded, it is assumed that the profile distortions are caused by effects from the scintillator material. Following the experience in high energy physics, a simple model was developed which takes into account quenching effects of excitonic carriers inside a scintillator in a heuristic way. Based on this model, the observed beam profiles can be understood qualitatively. Together with the model description, first comparisons with experiments will be presented, and new scintillators suitable for beam profile diagnostics will be discussed.  
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-WEOC03  
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WEPA09 Long Term Beam Phase Monitoring Based on HOM Signals in SC Cavities at FLASH HOM, cavity, controls, electron 388
 
  • J.H. Wei
    USTC/NSRL, Hefei, Anhui, People's Republic of China
  • N. Baboi
    DESY, Hamburg, Germany
  • L. Shi
    PSI, Villigen PSI, Switzerland
 
  The accelerating RF fields in superconducting cavities must be controlled precisely in FEL (Free Electron Laser) facilities to avoid beam energy spread and arrival time jitter. Otherwise the beam quality is degraded. The LLRF (Low Level Radio Frequency) system controls the RF field and provides a highly stable RF reference. A new type of beam phase determination technique based on beam-excited HOMs (Higher Order Modes) in cavities has been implemented. The two special couplers installed at both ends of each cavity, pick up the signals containing both the leakage of the accelerating field and the HOM signals. Therefore the signals can be used to calculate the beam phase directly with respect to the RF phase. We analysed the factors which may affect the result of the beam phase on a long-term based on an experimental platform at FLASH. Some phase drifts between the HOM-BPhM (Beam Phase Monitor) and the LLRF system phase measurement were observed and the reason will be further studied.  
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WEPA12 Differential Evolution Genetic Algorithm for Beam Bunch Temporal Reconstruction radiation, electron, laser, experiment 392
 
  • D. Wu, T.H. He, C.L. Lao, P. Li, J. Liu, X. Luo, Q. Pan, L.J. Shan, X. Shen, J. Wang, D.X. Xiao, L.G. Yan, P. Zhang, K. Zhou
    CAEP/IAE, Mianyang, Sichuan, People's Republic of China
  • Y. Liu
    CAEP/IFP, Mainyang, Sichuan, People's Republic of China
 
  Funding: Work supported by China National Natural Science Foundation of China with grant (11475159, 11505173, 11505174, 11575264, 11605190 and 11105019)
Coherent radiation, such as coherent transition radiation, coherent diffraction radiation, coherent synchrotron radiation, etc, can be used to measure the longitudinal distribution of the electron beam bunch of any length, as long as the coherent radiation spectrum can be measured. In many cases, the Kramers-Krönig relationship is used to reconstruct the temporal distribution of the beam from the coherent radiation spectrum. However, the extrapolation of the low frequency will introduce the uncertainty of the reconstruction. In this paper, an algorithm of differential evolution (DE) for temporal reconstruction is discussed. The DE reconstruction works well for the complex and ultrashort distribution. It will be an effectIve tool to accurately measure the femtosecond bunch temporal structure.
 
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WEPA13 Electro-Optic Modulator Based Beam Arrival Time Monitor for SXFEL* electron, pick-up, timing, laser 396
 
  • X.Q. Liu, L.F. Hua, L.W. Lai, Y.B. Leng, R.X. Yuan
    SINAP, Shanghai, People's Republic of China
  • N. Zhang
    SSRF, Shanghai, People's Republic of China
 
  Beam arrival time monitor (BAM) is an important tool to investigate the temporal characteristic of elec-tron bunch in free electron laser (FEL) like Shanghai soft X-ray Free Electron Laser (SXFEL). Since the timing jitter of electron bunch will affect the FEL's stability and the resolution of time-resolved experi-ment at FELs, it is necessary to precisely measure the electron bunch arrival time so as to reduce the timing jitter of the electron bunch with beam based feedback. The beam arrival time monitor based on electro-optic modulator (EOM) is already planned and will be de-veloped and tested at SXFEL in the next three years. Here the design and preliminary results of the EOM based beam arrival time monitor will be introduced in this paper.  
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WEPA15 Development of BAM Electronics in PAL-XFEL electron, electronics, pick-up, controls 400
 
  • D.C. Shin, J.H. Hong, H.-S. Kang, C. Kim, G. Kim, C.-K. Min
    PAL, Pohang, Republic of Korea
 
  We describe an electronics for electron bunch arrival time monitor (BAM) with a less than 10 femtosecond resolution, which was developed in 2017 and is currently in use at PAL-XFEL. When electron bunches go through an S-band monopole cavity, about 1 us long RF signal can be obtained to compare with a low phase noise RF reference. The differential phase jitter corresponds to the arrival time jitter of electron bunches. RF front-end (F/E) which converts the S-band pickup signal to intermediate frequency (IF) signal, is the essential part of a good time resolution. The digitizer and the signal processor of the BAM electronics are installed in an MTCA platform. This paper presents the design scheme, test results of the BAM electronics and future improvement plans.  
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WEPA20 First Results From the Bunch Arrival-Time Monitors at SwissFEL laser, pick-up, electron, MMI 420
 
  • V.R. Arsov, P. Chevtsov, S. Hunziker, M.G. Kaiser, D. Llorente Sancho, A. Romann, V. Schlott, M. Stadler, D.M. Treyer
    PSI, Villigen PSI, Switzerland
  • M. Dach
    Dach Consulting GmbH, Brugg, Switzerland
 
  Two Bunch Arrival-Time Monitors (BAM), based on fiber optical Mach-Zehnder intensity modulators, which encode the arrival-time information in the amplitude of the laser pulses delivered through a highly stable pulsed optical reference distribution system, have been commissioned and are operational at SwissFEL. The first BAM is at the RF-Gun, the second one is downstream the first bunch compressor. Both BAMs operate simultaneously and measure the arrival-time drift and jitter with less than 5 fs resolution. For the first time we have experimentally verified the excellent SwissFEL bunch stability. We have developed concepts and tested hardware, which enhance the commissioning and user operation. In particular we have successfully tested a tool for fast timing overlap between the electron bunch and the reference laser pulse, which allows fast system set-up and characterization. We have verified the capability for 2-bunch and 100 Hz operation. In comparison to the prototype detectors, which were operational at the SwissFEL test injector, we have achieved an improved BAM resolution in the range 10 pC - 200 pC.  
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WEPB09 Wire Scanner Measurements at the PAL-XFEL undulator, electron, emittance, controls 445
 
  • G. Kim, H.-S. Kang, C. Kim, B.G. Oh, D.C. Shin
    PAL, Pohang, Kyungbuk, Republic of Korea
 
  The PAL-XFEL, an X-ray Free electron laser user facility based on a 10 GeV normal conducting linear accelerator, have been operational at Pohang, South Korea. The wire scanners are installed for transverse beam profile measurement of the Linac and the Hard X-ray undulator section. The wire scanner is a useful device for emittance measurements in the Hard X-ray undulator section. In this paper, we describe the details of the wire scanner and the results of the measurements.  
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WEPB11 Spatial Resolution Improvement of OTR Monitors by Off-axis Light Collection radiation, electron, target, diagnostics 451
 
  • A. Potylitsyn, A.I. Novokshonov, L.G. Sukhikh
    TPU, Tomsk, Russia
  • G. Kube, A.I. Novokshonov
    DESY, Hamburg, Germany
 
  Funding: The work was partly supported by the program "Nauka" of the Russian Ministry of Education and Science, grant #3.1903.2017
The spatial resolution of an OTR monitor for electron beam profile diagnostics is determined by the resolution of the optical system and by the Point Spread Function (PSF) representing the single electron image. In the image plane, the PSF has a typical lobe-shape distribution with an inter-peak distance depending on wavelength and lens aperture ratio [*]. For a beam with a transverse rms size smaller than the distance, the reconstruction of the beam profile has several difficulties [**, ***]. We propose to reduce the PSF contribution and to improve the spatial resolution of an OTR monitor simply by rotating the lens optical axis with respect to the specular reflection direction. If the difference between the rotational angle and the lens aperture is much larger than the inverse Lorentz factor, the PSF has a Gaussian-like distribution which matches practically with the Airy distribution. Thus the resolution depends on wavelength and lens aperture. In principle, for lens apertures in the order of 0.1 rad such an approach should allow to measure beam sizes comparable to the wavelength of observation, using a simple deconvolution procedure for the measured image and the PSF.
* M. Castellano, V.Verzilov, Phys. Rev. ST-AB, 1 (1998).
** K.Kruchinin, S.T.Boogert, P.Karataev et al., Proc. IBIC 2013 (2013).
*** L.G. Sukhikh, A.P. Potylitsyn, G. Kube, Phys. Rev. AB 20 (2017).
 
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WEPC05 The European XFEL Wire Scanner System detector, optics, electron, undulator 498
 
  • T. Lensch, S. Liu, M. Scholz
    DESY, Hamburg, Germany
 
  The European-XFEL (E-XFEL) is an X-ray Free Electron Laser facility located in Hamburg (Germany). The superconducting accelerator for up to 17.5 GeV electrons will provide photons simultaneously to several user stations. Currently 12 Wire Scanner units are used to image transverse beam profiles in the high energy sections. These scanners provide a slow scan mode which is currently used to measure beam emittance and beam halo distributions. When operating with long bunch trains (>100 bunches) also fast scans are planned to measure beam sizes in an almost nondestructive manner. Scattered electrons can be detected with regular Beam Loss Monitors (BLM) as well as dedicated wire scanner detectors. Latter are installed in different variants at certain positions in the machine. Further developments are ongoing to optimize the sensitivity of the detectors to be able to measure both, beam halo and beam cores within the same measurement with the same detector. This paper describes the current status of the system and examples of different slow scan measurements.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-WEPC05  
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WEPC06 The New Diagnostic Suite for the Echo Enabled Harmonic Generation Experiment at FERMI laser, electron, diagnostics, bunching 501
 
  • M. Veronese, A. Abrami, E. Allaria, M. Bossi, I. Cudin, M.B. Danailov, R. De Monte, M. Ferianis, F. Giacuzzo, S. Grulja, G. Kurdi, P. Rebernik Ribič, R. Sauro, G. Strangolino
    Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
 
  The Echo Enabled Harmonic Generation (EEHG) experiment has been implemented on the FEL2 line of the FERMI FEL at Elettra (Italy). The main purpose is to validate the expected performance improvements at short wavelengths before a dedicated major upgrade is deployed. This paper describes the new diagnostics and the operational experience with them during the EEHG experiment. By means of a multi position vacuum vertical manipulator, different optical components are positioned on the electron and seed laser path. Both transverse and longitudinal measurements are performed. A YAG:Ce screen (e beam) and a terbium doped UV scintillator (laser) are imaged on a dedicated CMOS camera. For the temporal alignment, an OTR screen and a scattering surface are used to steer radiation from the e-beam and laser, onto a fast photodetector. Also coherent OTR radiation, due to micro-bunching, is acquired by means of a PbSe photodetector. Finally, for the normal EEHG operation, the laser beam is injected on the electron beam axis by means of a UV reflecting mirror. The results of the installed diagnostics commissioning are here presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-WEPC06  
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THOA02 High-Speed Direct Sampling FMC for Beam Diagnostic and Accelerator Protection Applications interface, controls, diagnostics, timing 534
 
  • J. Zink, M.K. Czwalinna, M. Fenner, S. Jabłoński, J. Marjanovic, H. Schlarb
    DESY, Hamburg, Germany
 
  The rapid development in the field of digitizers is leading to Analog-to-Digital Converters (ADC) with ever higher sampling rates. Nowadays many high-speed digitizers for RF applications and radio communication are available, which can sample broadband signals, without the need of down converters. These ADCs fit perfectly into beam instrumentation and diagnostic applications, e.g. Bunch Arrival time Monitor (BAM), klystron life-time management or continuous wave synchronization. To cover all these high-frequency diagnostic applications, DESY has developed a direct sampling FMC digitizer board based on a high-speed ADC with an analog input bandwidth of 2.7 GHz. A high-speed data acquisition system capable of acquiring 2 channels at 800 MSP/s will be presented. As first model application of the versatile digitizer board is the coarse bunch arrival time diagnostics in the free electron laser FLASH at DESY.  
slides icon Slides THOA02 [5.817 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-THOA02  
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