R. Panaś, A.I. Wawrzyniak
NSRC SOLARIS, Kraków, Poland
A. Curcio
LNF-INFN, Frascati, Italy
K. Łasocha
CERN, Meyrin, Switzerland
This paper presents a natural extension of prior theoretical investigations regarding the utilization of coherent diffraction radiation for assessing longitudinal characteristics of electron beams at Solaris. The study focuses on the measurement results obtained at the linac injector of the Solaris synchrotron and their analysis through a theoretical model. The findings are compared with previous estimates of the electron beam longitudinal profile. This paper contributes to the future diagnostics at the first Polish free electron laser (PolFEL) project, where it will be used for the optimization of particle accelerator performance.
B. Lorbeer, H.T. Duhme, I. Krouptchenkov, T. Lensch, D. Lipka, M. Werner
DESY, Hamburg, Germany
The European X-ray free-electron laser (E-XFEL) and the FLASH2020+ project for the free electron laser Hamburg (FLASH) at DESY in Hamburg, Germany foresee several machine upgrades in the years to come. At FLASH a whole undulator section in a shutdown starting in summer 2024 and finishing in autumn 2025 is going to be rebuild. Existing button beam position monitors installed in this section of the machine do not deliver sufficient signal strength for future required resolution specification and orbit feedback optimization for machine operation. The resolution limitations will be overcome by replacing the button-based beam position monitors with in-house developed cavity beam position monitors and compact microTCA based radio frequency receiver read-out electronics. The measurement system has been tested and evaluated in a test setup at FLASH.
T. Lensch, D. Lipka, Re. Neumann, M. Werner
DESY, Hamburg, Germany
The SINBAD (Short and INnovative Bunches and Ac-celerators at DESY) facility, also called ARES (Acceler-ator Research Experiment at SINBAD), is a conventional S-band linear RF accelerator allowing the production of lowcharge ultra-short electron bunches within a range of currently 0.01 pC to 250 pC. The R&D accelerator also hosts various experiments. Especially for the medical eFLASH experiment an absolute, non-destructive charge measurement is needed. Therefore different types of monitors are installed along the 45 m long machine: A new Faraday Cup design had been simulated and realized. Further two resonant cavities (Dark Current monitors) and two beam charge transfomers (Toroids) are installed. Both, Dark Current Monitors and Toroids are calibrated independently with laboratory setups. At the end of the accelerator a Bergoz Turbo-ICT is installed. This paper will give an overview of the current installations of charge monitors at ARES and compare their measured linearity and resolution.
S. Klaproth, A. Penirschke
THM, Friedberg, Germany
H. De Gersem
TEMF, TU Darmstadt, Darmstadt, Germany
R. Singh
GSI, Darmstadt, Germany
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) GHz transition radiation monitors (GTRs) can be used to measure longitudinal beam profiles even for low ß beams. In comparison to traditional methods e.g., Fast Faraday Cups (FFCs) and Feschenko monitors, GTRs are a non-destructive measurement method and are able to resolve bunch-by-bunch longitudinal profiles at the same time. In our case, we plan to measure the transition radiation outside the beam line through an RF-window with an 8 GHz broad band antenna. At the border of the RF-window the transition radiation is partially reflected propagating in the beam line backwards. In this contribution, we show a study of different geometries to suppress reflections generated at the transition to the RF-window. For higher permittivity the strength of these reflections becomes stronger, simultaneously reducing the measurable signal strength at the antenna. Secondly the RF-window material must be UHV usable and should be durable like Alumina or Peek.
B.E.J. Scheible, A. Penirschke
THM, Friedberg, Germany
W. Ackermann, H. De Gersem
TEMF, TU Darmstadt, Darmstadt, Germany
M.K. Czwalinna, T.A. Nazer, H. Schlarb, S. Vilcins
DESY, Hamburg, Germany
M. Freitag, M. Kuntzsch
HZDR, Dresden, Germany
Funding:This work is supported by the German Federal Ministry of Education and Research (BMBF) under Contract No. 05K19RO1 and 05K22RO2. A vacuum sealed prototype of an electro-optical bunch-arrival-time monitor has been commissioned in 2023. It comprises of a pickup-structure and a low-pi-voltage ultra-wideband traveling wave electro-optical modulator. The stainless-steel body of the pickup structure is partially produced by additive manufacturing and comprises four pickups as well as an integrated combination network on a printed circuit board. This novel design aims to enable single-shot bunch-arrival-time measurements for electron beams in free-electron lasers with single-digit fs precision for low bunch charges down to 1 pC. The theoretical jitter charge product has been estimated by simulation and modeling to be in the order of 9 fs pC. The new prototype is tailored for validation experiments at the ELBE accelerator beamline. In this contribution first measurement results are presented.
D.C. Shin, H.-S. Kang, G. Kim, C.-K. Min, G. Mun
PAL, Pohang, Republic of Korea
We introduce the RF Phase Shifter (RPS) developed in the Pohang Accelerator Laboratory X-ray Free-Electron Laser (PAL-XFEL) to control the timing of optical laser system. This equipment is designed to finely adjust the timing of laser pulses with femtosecond scale by manipulating the phase of the RF reference using a couple of Direct Digital Synthesizer (DDS) devices. Furthermore, it is designed with low phase noise and low phase drift features in order to minimize the impact on the system in an open-loop operation. Currently these units are installed at the Injection site, Hard X-ray and Soft X-ray Beamline. They are implemented for the feedback control of the photocathode gun phase at the Injector and for the use in pump-probe experiments at the Beamlines. This paper describes the design, fabrication, and experimental results of the RPS, as well as its usage status at PAL-XFEL.
The lasing performance of a Free Electron Laser (FEL) strongly relies on a precise characterization of the electron bunch length and on the control and stabilization of the bunch compression settings of the machine under normal user operations. In a FEL driver linac, the so-called Bunch Compressor Monitors (BCMs) normally ensure the non-invasive monitoring of the electron bunch length. BCMs, being sensitive to the temporal coherent threshold of the radiation energy emitted by the electron beam crossing the last dipole of a magnetic chicane or a holed diffraction screen just downstream, can provide a bunch length dependent signal resulting from the integration of the detected radiation pulse energy over the acceptance frequency band of the detector. Thanks to the non-invasiveness, BCMs are primary diagnostics in a FEL to stabilize the bunch compression by feeding back the RF settings of the accelerating structure. In this contribution, we present a formal method to determine an absolute measurement of the electron bunch length from the analysis of a BCM signal (*). (*) G.L. Orlandi, Absolute and non-invasive determination of the electron bunch length in a Free Electron Laser using a Bunch Compressor Monitor, https://doi.org/10.48550/arXiv.2305.17042, https://doi.org/10.21203/rs.3.rs-3228455/v1
L.W. Lai, S.S. Cao, X.Q. Liu, Y.M. Zhou
SARI-CAS, Pudong, Shanghai, People’s Republic of China
J. Chen
SSRF, Shanghai, People’s Republic of China
R. Meng
SINAP, Shanghai, People’s Republic of China
Funding:Work supported by The National Science Foundation of China (Grant No.12175293). Youth Innovation Promotion Association, CAS (Grant No. 2019290) A RF direct sampling beam signal processor has been developed in SSRF. It mainly consists of four channels RF direct sampling ADCs and a SoC FPGA. The ADC is 9GHz bandwidth and 2.6GHz sampling rate. A prototype of RF module contains band pass filter, low noise ampli-fier and step attenuator has been designed for SHINE cavity BPM system. Then a novel cavity BPM electronic including the processor and the RF module has been built for SHINE. The performance of the electronic has been analyzed and evaluated in lab. The amplitude relative error is 2.0×10-4,which is better than the required 1×10-3 on cavity BPM system. The phase error is 14fs, also bet-ter than the requirement of RF BAM system. The algorithm and the implementation in FPGA have been introduced. Corresponding author: lailw@sari.ac.cn
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