A. Brauch, M. Arnold, J. Enders, L.E. Jürgensen, N. Pietralla, S. Weih
TU Darmstadt, Darmstadt, Germany
Funding:*Work supported by DFG (GRK 2128) and the State of Hesse within the Research Cluster ELEMENTS (Project ID 500/10.006). A high-quality beam is necessary for electron scattering experiments at the superconducting Darmstadt electron linear accelerator S-DALINAC. An optimization of the bunch length to typical values of < 2 ps is performed to reach a high energy resolution of 1e-4. Currently, this is accomplished by inducing a linear momentum spread on the bunch in one of the accelerating cavities. The bunch length can then be measured with a target downstream. This method is time consuming and provides only an upper limit of the bunch length. Two new setups for bunch length measurements will improve the optimization process significantly. On the one hand, a new diagnostic beam line is set up in the low energy beam area. It includes a deflecting copper cavity used for measuring the bunch length by shearing the bunch and projecting its length on a target. On the other hand, a streak camera placed at different positions downstream the injector and the main linac will be used to measure the bunch length. Optical transition radiation from an aluminium coated kapton target is used to perform this measurement. The present layout of both systems and their current status will be presented in this contribution.
Design Considerations of the Corrugated Structures in a Vacuum Chamber for Impedance Studies at KARA
100
S. Maier, M. Brosi, H.J. Cha, A. Mochihashi, A.-S. Müller, M.J. Nasse, P. Schreiber, M. Schwarz
KIT, Karlsruhe, Germany
Funding:Supported by the DFG project 431704792 in the ANR-DFG collaboration project ULTRASYNC and by the Doctoral School KSETA. Two parallel, corrugated plates will be installed at the KIT storage ring KARA (KArlsruhe Research Accelerator). This impedance manipulation structure can be used to study and eventually control the electron beam dynamics and the emitted coherent synchrotron radiation (CSR) at KARA. In this contribution, we present the design of the impedance manipulation structure with corrugated plates, simulation results showing the influence of different corrugation parameters on its impedance, and the impact of this additional impedance source on the temporal changes in the emitted CSR in the presence of the microbunching instability.
Improvements in Longitudinal Phase Space Tomography at PITZ
105
N. Aftab, Z. Aboulbanine, P. Boonpornprasert, G.Z. Georgiev, J. Good, M. Groß, A. Hoffmann, M. Krasilnikov, X.-K. Li, A. Lueangaramwong, R. Niemczyk, A. Oppelt, H.J. Qian, C.J. Richard, F. Stephan, G. Vashchenko
DESY Zeuthen, Zeuthen, Germany
W. Hillert
University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
A.J. Reader
KCL, London, United Kingdom
Methodical studies to improve the longitudinal phase space (LPS) tomography of space-charge dominated electron beams were carried out at the Photo Injector Test facility at DESY in Zeuthen (PITZ). An analytical model was developed to quantify mean momentum, RMS energy spread, bunch length and phase advance. Phase advance analysis determined the booster phase scan range and step size to be used for obtaining momentum projections. A slit was introduced before the booster to truncate the beam in transverse plane to strongly reduce the space charge effects. The signal resolution of this truncated beam was improved by careful beta function control at the reference screen of the momentum measurements. The reconstruction algorithm was changed from Algebraic Reconstruction Technique (ART) to Image Space Reconstruction Algorithm (ISRA) owing to its assurance of non-negative solutions. In addition, the initial physically justified assumption of LPS, based on low-energy section measurements, was established to clear out noise-like artefacts. This paper will highlight the improvements made in the LPS tomography and compare the simulated and experimental results.
Low Gain Avalanche Detector Application for Beam Monitoring
109
V. Kedych, T. Galatyuk, W. Krüger
TU Darmstadt, Darmstadt, Germany
T. Galatyuk, S. Linev, J. Pietraszko, C.J. Schmidt, M. Träger, M. Traxler, F. Ulrich-Pur
GSI, Darmstadt, Germany
J. Michel
Goethe Universität Frankfurt, Frankfurt am Main, Germany
A. Rost
FAIR, Darmstadt, Germany
V. Svintozelskyi
Taras Shevchenko National University of Kyiv, Kyiv, Ukraine
Funding:This work has been supported by DFG under GRK 2128 The S-DALINAC is a superconductive linear electron accelerator operating at 3 GHz and allows operation in energy recovery mode (ERL). For the operation in the ERL mode accelerated and decelerated beams travel inside the same beamline but not necessarily share the same orbit. That leads to a bunch rate of 6 GHz. Non-destructive monitoring tools that allow optimization of acceleration and deceleration processes and achieve high recovery efficiency are important for operation in the ERL mode. The Low Gain Avalanche Detector (LGAD) is a silicon detector with internal gain layer optimized for 4-D tracking with timing resolution below 50 ps* which makes it a promising candidate for beam time structure monitoring. In this contribution we present the status of the first proof of principle beam time structure measurement with LGAD sensors at S-DALINAC in normal operation mode together with future activities overview. * J.Pietraszko, et al., Low Gain Avalanche Detectors for the HADES reaction time (T0) detector upgrade, Eur. Phys. J. A 56, 183 (2020)
N. Milas, G.S. Fedel, A.A. Gorzawski, J.J. Jamróz, J.P.S. Martins
ESS, Lund, Sweden
The European Spallation Source (ESS), currently under construction and initial commissioning in Lund, Sweden, will be the brightest spallation neutron source in the world, when its driving proton linac achieves the design power of 5 MW at 2 GeV. Such a high power requires production, efficient acceleration, and almost no-loss transport of a high current beam, thus making design and beam commissioning of this machine challenging. The commissioning runs of 2021 and early 2022 were the first where the master timing system for the linac was fully available. As a consequence of that, the beam actuators and beam monitoring equipment relied fully on timing events sent accross the machine, not only to be triggered to act but also to get the configuration. In this paper, we describe the timing system as available today, present how we define and create the beam pulses using the available parameters. We also present planned future upgrades and other outlook for the system.
Simulation and Measurements of the Fast Faraday Cups at GSI UNILAC
286
R. Singh, P. Forck, T. Reichert, A. Reiter
GSI, Darmstadt, Germany
S. Klaproth
THM, Friedberg, Germany
G.O. Rodrigues
IUAC, New Delhi, India
Funding:This work is supported by the German Federal Ministry of Education and Research (BMBF) under contract no. 05P21RORB2. Joint Project 05P2021 - R&D Accelerator (DIAGNOSE) The longitudinal charge profiles of the high intensity heavy ion beam accelerated at the GSI UNILAC upto 11.4 MeV/u can differ significantly in consecutive macro-pulses. Variations in bunch shape and mean energy were also observed within a single macro-pulse. In order to have an accurate and fast determination of bunch shape and its evolution within a macro-pulse, a study of fast Faraday Cup designs is underway at GSI. In this contribution, we present CST particle in cell (PIC) simulations of radially coupled co-axial Fast Faraday Cup (RCFFC) and conventional axially coupled FFC (ACFFC) design. The simulation results are compared to the measurements performed under comparable beam conditions primarily with RCFFCs. A rather large impact of secondary electron emission is observed in simulations and experiments. The biasing of the FFC central electrode as a mitigation mechanism on the measured profiles is discussed.
Study on Beam Length Measurement Technique Using Highspeed Oscilloscope
HS. Wang
SSRF, Shanghai, People’s Republic of China
In order to study the nonlinear beam dynamics in the storage ring, the SSRF BI group developed the software package HOTPCAP, which is used to extract the bunch-by-bunch 3D beam position information from the BPM electrode signal. In order to enhance the function of this software, we studied the beam length extraction method from digitized BPM electrodes signal. By analyzing the signal spectrum distribution for each bunch and each turn and gaussian fitting in frequency domain, bunch length information be extracted. Compared with the traditional longitudinal diagnostic tool streak camera, this method can obtain and store measurement data as long as ten ms while maintaining the time resolution of ps level, which is a powerful diagnostics tool for study of injection transient stage and longitudinal instability. In this paper, the hardware and software architecture of the system and the beam experimental results obtained during the third harmonic cavity commissioning are introduced.
Coherent Difraction Radiation for Longitudinal Electron Beam Characteristics
291
R. Panaś
NSRC SOLARIS, Kraków, Poland
A. Curcio
CLPU, Villamayor, Spain
K. Łasocha
Jagiellonian University, Kraków, Poland
For the needs of diagnostics of the longitudinal electron beam characteristics at the first Polish free electron laser (PolFEL) project, a Coherent Diffraction Radiation (CDR) system is being developed and tested. It will allow for nondestructive bunch length measurement based on the power balance of CDR radiation collected by Schottky diodes in different ranges of sub-THz radiation. The first tests and measurements will be performed at the end of the Solaris synchrotron injector linac, where the beam profile is already known from previous studies. In addition the camera system with automatic focus was developed and tested. In this contribution the theoretical background of the measurement, calculations and first experimental steps will be presented.
Modeling and Experimental Evaluation of a Bunch Arrival-Time Monitor with Rod-Shaped Pickups and a Low-Pi-Voltage Ultra-Wideband Traveling Wave Electro-Optic Modulator for X-Ray Free-Electron Lasers
447
K. Kuzmin, E. Bründermann, A.-S. Müller, G. Niehues
KIT, Karlsruhe, Germany
W. Ackermann, H. De Gersem
TEMF, TU Darmstadt, Darmstadt, Germany
M.K. Czwalinna, H. Schlarb
DESY, Hamburg, Germany
C. Eschenbaum, C. Koos, A. Kotz, A. Schwarzenberger
IPQ KIT, Karlsruhe, Germany
A. Penirschke, B.E.J. Scheible
THM, Friedberg, Germany
X-ray Free-Electron Laser (XFEL) facilities, such as the 3.4-km European XFEL, use all-optical links with electro-optic bunch arrival-time monitors (BAM) for a long-range synchronization. The current BAM systems achieve a resolution of 3.5 fs for 250 pC bunches. Precise bunch arrival timing is essential for experiments, which study ultra-fast dynamical phenomena with highest temporal resolution. These experiments will crucially rely on femtosecond pulses from bunch charges well below 20 pC. The state-of-the-art BAMs are not allowing accurate timing for operation with such low bunch charges. Here we report on the progress in development of an advanced BAM (system) based on rod-shaped pickups mounted on a printed circuit board and ultra-wideband travelling-wave electro-optic modulators with low operating voltages. We perform modeling and experimental evaluation for the fabricated pickups and electro-optic modulators and analytically estimate timing jitter for the advanced BAM system. We discuss an experimental setup to demonstrate joint operation of new pickups and wideband EO modulators for low bunch charges less than 5 pC.
Installation and Commissioning of the Pulsed Optical Timing System Extension
451
F. Rossi, M. Ferianis
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
At the FERMI FEL user facility, a fully optical timing system has been operated, to synchronize it, since the start of machine commissioning, back in 2009. In the past years the system has been progressively extended to support more clients. The latest upgrade is focusing on the pulsed subsystem which provides the phase reference to remote lasers and the bunch arrival monitor diagnostic stations. In origin the pulsed subsystem had a capacity to feed simultaneously six stabilized fiber links. The upgrade to the original layout makes it possible to install up to eight new additional links. Here we will describe the new setup and the results achieved in terms of short- and long-term stability.
Status of a Monitor Design for Single-Shot Electro-Optical Bunch Profile Measurements at FCC-ee
455
M. Reißig, E. Bründermann, S. Funkner, B. Härer, A.-S. Müller, G. Niehues, M.M. Patil, R. Ruprecht, C. Widmann
KIT, Eggenstein-Leopoldshafen, Germany
Funding:Supported by the Doctoral School KSETA. C. W. achnowledges funding by BMBF contract number 05K19VKD. FCCIS is funded by the EU’s Horizon 2020 research and innovation programme under grant No 951754. At the KIT electron storage ring KARA (Karlsruhe Research Accellerator) an electro-optical (EO) near-field monitor is in operation performing single-shot, turn-by-turn measurements of the longitudinal bunch profile using electro-optical spectral decoding (EOSD). In context of the Future Circular Collider Innovation Study (FCCIS), a similar setup is investigated with the aim to monitor the longitudinal bunch profile of each bunch for dedicated top-up injection at the future electron-positron collider FCC-ee. This contribution presents the status of a monitor design adapted to cope with the high-current and high-energy lepton beams foreseen at FCC-ee.
Studies on Radially Coupled Fast Faraday Cups to Minimize Field Dilution and Secondary Electron Emission at Low Intensities of Heavy Ions
460
G.O. Rodrigues, S. Kumar, K. Mal, R. Mehta, C.P. Safvan
IUAC, New Delhi, India
R. Singh
GSI, Darmstadt, Germany
Fast Faraday Cups (FFCs) are interceptive beam diagnostic devices used to measure fast signals from sub-nanosecond bunched beams and the operation of these devices is a well-established technique. However, for short bunch length measurements in non-relativistic regimes with ion beams, the measured profile is diluted due to field elongation and distortion by the emission of secondary electrons. Additionally, for short bunches with the expected intensities envisaged in the High Current Injector at the Inter University Accelerator Centre, the impedance matching of the EM structure puts severe design constraints. This work presents a detailed study on the modification of a radially-coupled coaxial FFC [1]. The field dilution and secondary electron emission aspects are modelled through EM simulations and techniques to minimise these effects are explored. This has resulted in a new design, which has a better signal to noise ratio and benefits from a more accurate bunched beam measurement. [1] Carneiro, J.-P., et al. ’Longitudinal Beam Dynamics Studies at the Pip-II Injector Test Facility.’ International Journal of Modern Physics A, vol. 34, no. 36, 2019, p.1942013
Optimization Study of Beam Position and Angular Jitter Independent Bunch Length Monitor for Awake Run 2
465
C. Davut
The University of Manchester, Manchester, United Kingdom
Ö. Apsimon
The University of Liverpool, Liverpool, United Kingdom
P. Karataev
Royal Holloway, University of London, Surrey, United Kingdom
T. Lefèvre, S. Mazzoni
CERN, Meyrin, Switzerland
G.X. Xia
UMAN, Manchester, United Kingdom
In this paper, a study using the Polarization Current Approach (PCA) model is performed to optimize the design of a short bunch length monitor using two dielectric radiators that produce coherent Cherenkov Diffraction Radiation (ChDR). The electromagnetic power emitted from each radiator is measuring a different part of the bunch spectrum using Schottky diodes. For various bunch lengths, the coherent ChDR spectrums are calculated to find the most suitable frequency bands for the detection system. ChDR intensities measured by each detector are estimated for different impact parameters to explore the dependence of bunch length monitor on beam position and angular jitter. It is found that, in the present configuration, the effects of beam position and angular jitter are negligibly small for bunch length measurement. * Shevelev, M. V., & Konkov, A. S. (2014). Journal of Experimental and Theoretical Physics, 118(4), 501-511. ** Curcio, A. et al. (2020). Physical Review Accelerators and Beams, 23(2), 022802.
First Measurement of Longitudinal Profile of High-Power and Low-Energy H− Beam by Using Bunch Shape Monitor with Graphite Target
532
R. Kitamura
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
At J-PARC Linac, bunch shape monitors (BSMs) have been used to measure a longitudinal profile of high power H− beam. Operational principle of the monitor is similar to that of the streak-camera. The BSM inserts a biased-solid target into H− beam to extract and accelerate secondary electrons. These electrons are then modulated with synchronized RF. After passing through dipole B field, a longitudinal profile is converted to a transverse one. For the BSM, a choice of target material is essential to reduce beam loss and to have sufficient tolerance for breakage by the interaction with high power beams. The BSM with graphite target realized the measurement of high-power 3 MeV beam for the first time.
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Experimental Verification and Analysis of Beam Loading Effect Based on Precise Bunch-by-Bunch 3d Position Measurement (remote contribution)
Y.M. Zhou
SSRF, Shanghai, People’s Republic of China
Y.M. Zhou
SARI-CAS, Pudong, Shanghai, People’s Republic of China
Beam loading effect is one of the main bottlenecks of synchrotron radiation light source to further improve performance. The theoretical analysis and numerical simulation of beam loading effect had been done very well, but the corresponding diagnostics tools relatively poor, usually only streak camera is used to observe the synchronous phase distribution and the intensity distribution in bunch train. SSRF developed precise bunch-by-bunch 3D beam position measurement system. Equipped with this system not only steady-state beam parameters (filling pattern, synchronous phase, bunch lifetime), can be accurately measured and recorded, but also transient stage data can be perfectly captured and recorded. Therefore, the beam loading effect can be more comprehensive and accurate experimental verification and analysis. In this paper, the measurement results of synchronous phase, synchronous tune, synchronous oscillation damping time and other parameters with and without third harmonic cavity are introduced and discussed.
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Single-Shot Electro-Optic Detection of Bunch Shapes and THz Pulses: Fundamental Temporal Resolution Limitations and Cures Using the DEOS Strategy
536
C. Szwaj, S. Bielawski, C. Evain, E. Roussel
PhLAM/CERLA, Villeneuve d’Ascq, France
C. Gerth, B. Steffen
DESY, Hamburg, Germany
B. Jalali
UCLA, Los Angeles, California, USA
Funding:ULTRASYNC ANR-DFG project, CPER Photonics for Society, CEMPI LABEX Recording electric field evolutions in single-shot and with sub-picosecond resolution is required in electron bunch diagnostics, and THz applications. A popular strategy consists of transferring the unknown electric field shape onto a chirped laser pulse, which is eventually analyzed. The technique has been investigated and/or been used as routine diagnostics at FELIX, DESY, PSI, Eu-XFEL, KARA, SOLEIL, etc. However fundamental time-resolution limitations have been strongly limiting the potential of these methods. We review recent results on a strategy designed for overcoming this limit: DEOS [1] (Diversity Electro-Optic Sampling). A special experimental design enables to reconstruct numerically the input electric signal with unprecedented temporal resolution. As a result, 200 fs temporal resolution over more than 10 ps recording length could be obtained at European XFEL - a performance that could not be realized using classical spectrally-decoded electro-optic detection. Although DEOS uses a radically novel conceptual approach, its implementation requires few hardware modifications of currently operating chirped pulse electro-optic detection systems. [1] E. Roussel, C. Szwaj, C. Evain, B. Steffen, C. Gerth, B. Jalali and S. Bielawski, Light: Science & Applications 11, 14 (2022). https://www.nature.com/articles/s41377-021-00696-2
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Advancing the Steady State Microbunching Experiment at the MLS With an Enhanced Detection Scheme
A. Kruschinski, J. Feikes
HZB, Berlin, Germany
A. Hoehl, R. Klein, J. Puls
PTB, Berlin, Germany
The Steady State Microbunching (SSMB) Proof-of-Principle experiment at the Metrology Light source (MLS) has shown the viability of the concept and investigates the physics behind the mechanism of microbunching, which is envisioned to provide very high power coherent synchrotron radiation at a storage ring facility. In the initial stages of the experiment, it was not possible to detect the coherent radiation of interest directly. A new detection scheme that overcomes this difficulty using fast optical switches is presented, as well as newest results obtained.
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