Keyword: LLRF
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MOC3O07 Low Level RF Control Implementation and Simultaneous Operation of Two FEL Undulator Beamlines at FLASH operation, controls, laser, undulator 1
  • V. Ayvazyan, S. Ackermann, J. Branlard, B. Faatz, M.K. Grecki, O. Hensler, S. Pfeiffer, H. Schlarb, Ch. Schmidt, M. Scholz, S. Schreiber
    DESY, Hamburg, Germany
  • A. Piotrowski
    FastLogic Sp. z o.o., Łódź, Poland
  The Free-Electron Laser in Hamburg (FLASH) is a user facility delivering femtosecond short radiation pulses in the wavelength range between 4.2 and 45 nm using the SASE principle. The tests performed in the last few years have shown that two FLASH undulator beamlines can deliver FEL radiation simultaneously to users with a large variety of parameters such as radiation wavelength, pulse duration, intra-bunch spacing etc. FLASH has two injector lasers on the cathode of the gun to deliver different bunch trains with different charges, needed for different bunch lengths. Because the compression settings depend on the charge of bunches the low level RF system needs to be able to supply different compression for both beamlines. The functionality of the controller has been extended to provide intra-pulse amplitude and phase changes while maintaining the RF field amplitude and the phase stability requirements. The RF parameter adjustment and tuning for RF gun and accelerating modules can be done independently for both laser systems. Having different amplitudes and phases within the RF pulse in several RF stations simultaneous lasing of both systems has been demonstrated.  
slides icon Slides MOC3O07 [4.640 MB]  
MOPGF014 LLRF Controls Upgrade for the LCLS XTCAV project at SLAC controls, linac, klystron, software 1
  • S. Condamoor, Y. Ding, P. Krejcik, H. Loos, T.J. Maxwell, J.J. Olsen
    SLAC, Menlo Park, California, USA
  Funding: This work was performed in support of the LCLS project at SLAC. Work supported by the U.S. Department of Energy under contract number DE-AC02-76SF00515.
SLAC's Low Level Radio Frequency (LLRF) controls software for the S-Band deflecting structures needed to be upgraded significantly when a new X-Band transverse deflecting cavity (XTCAV) was installed downstream of the LCLS undulators in Spring 2013 to assist in FEL diagnostics such as characterizing the temporal profile of X-ray pulses that vary shot-to-shot. The unique location of the XTCAV in the beamline posed several challenges. A new design of the Modulator and Klystron control Support Unit (MKSU-II) for interlocking was added at the XTCAV controls station that required new software development. The timing setup was also different from the rest of the Linac. This paper outlines the LLRF controls layout for the XTCAV and discusses the manner in which the challenges were addressed. XTCAV has now become a successful tool for gathering data that enables reconstruction of X-ray FEL power profiles with greater resolution.
SLAC Publication Number: SLAC-PUB-16414
poster icon Poster MOPGF014 [3.646 MB]  
MOPGF079 European XFEL Cavities Piezoelectric Tuners Control Range Optimization cavity, operation, controls, linac 1
  • W. Cichalewski, A. Napieralski
    TUL-DMCS, Łódź, Poland
  • J. Branlard, Ch. Schmidt
    DESY, Hamburg, Germany
  The piezo based control of the superconducting cavity tuning has been under the development over last years. Automated compensation of Lorentz force detuning of FLASH and European X-FEL resonators allowed to maintain cavities in resonance operation even for high acceleration gradients (in range of 30 MV/m). It should be emphasized that cavity resonance control consists of two independent subsystems. First of all the slow motor tuner based system can be used for slow, wide range mechanical tuning (range of hundreds of kHz). Additionally the piezo tuning system allows for fine, dynamic compensation in a range of ~1 kHz. In mentioned pulse mode experiments (like FLASH), the piezo regulation budget should be preserved for in-pulse detuning control. In order to maintain optimal cavity frequency adjustment capabilities slow motor tuners should automatically act on the static detuning component at the same time. This paper presents work concerning development, implementation and evaluation of automatic superconducting cavity frequency control towards piezo range optimization. FLASH and X-FEL dedicated cavities tuning control experiences are also summarized.  
poster icon Poster MOPGF079 [0.932 MB]  
MOPGF093 Real-time Beam Loading Compensation for Single SRF Cavity LLRF Regulation real-time, cavity, detector, electron 1
  • I. Rutkowski, M. Grzegrzólka
    Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland
  • Ł. Butkowski, Ch. Schmidt
    DESY, Hamburg, Germany
  • M. Kuntzsch
    HZDR, Dresden, Germany
  Stable and reproducible generation of a photon beam at Free Electron Lasers (FELs) necessitates a low energy spread of the electron beam. A low level radio frequency (LLRF) control system stabilizes the RF field inside accelerating modules. An electron beam passing through the cavity induces a drop in the actual stored field proportional to the charge, the cavity shunt impedance, and the bunch repetition rate. The feedback loop compensates for the perturbation after the accelerating gradient drops. Due to the digital loop delay and limited bandwidth of the closed loop system, this disturbance induces control errors which can increase beam energy spread. An open-loop controller uses information obtained from the beam diagnostic systems accounting in real-time for fluctuations of the beam current. This paper describes the bunch charge detection scheme, its implementation, as well as results of the tests performed on the ELBE (Electron Linac for beams with high Brilliance and low Emittance) radiation source at the HZDR (Helmholtz-Zentrum Dresden-Rossendorf) facility.  
poster icon Poster MOPGF093 [4.046 MB]  
MOPGF114 Controls Interface into the Low-Level RF System in the ARIEL e-Linac at TRIUMF controls, ISAC, interface, linac 1
  • J.J. Pon, K. Ezawa, R. Keitel, R.B. Nussbaumer, J.E. Richards, M. Rowe, P.J. Yogendran
    TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada
  Phase 1 of TRIUMF Advanced Rare Isotope Laboratory (ARIEL) was completed in September 2014. At phase 1, the Low-Level RF (LLRF) system of ARIEL's electron linear accelerator (e-Linac) consists of a buncher and a deflector, one single-cavity injector cryomodule and the first cavity of two dual-cavity accelerating cryomodules. The model for the e-Linac LLRF system is largely based on the experience gained from the fully-commissioned TRIUMF ISAC-II linear accelerator (linac). Similarly, the EPICS-based Controls for the e-Linac LLRF builds on the lessons learned with the linac LLRF Controls. This paper describes the interface between the ARIEL Control System (ACS) and the e-Linac LLRF using EPICS ASYN/StreamDevice and a SCPI-like protocol. Also discussed are the ACS EDM displays and future plans for LLRF Controls.  
poster icon Poster MOPGF114 [3.428 MB]  
WEPGF014 A Data Acquisition System for Abnormal RF Waveform at SACLA GUI, controls, cavity, data-acquisition 1
  • M. Ishii, M. Kago
    JASRI/SPring-8, Hyogo-ken, Japan
  • T. Fukui
    RIKEN SPring-8 Center, Innovative Light Sources Division, Hyogo, Japan
  • T. Hasegawa, M. Yoshioka
    SES, Hyogo-pref., Japan
  • T. Inagaki, H. Maesaka, T. Ohshima, Y. Otake
    RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
  • T. Maruyama
    RIKEN/SPring-8, Hyogo, Japan
  At the X-ray Free Electron Laser (XFEL) facility, SACLA, an event-synchronized data acquisition system has been utilized for the XFEL operation. This system collects every shot-by-shot data, such as point data of the phase and amplitude of the RF cavity pickup signals, in synchronization with the beam operation cycle. This system also acquires RF waveform data every 10 minutes. In addition to the periodic waveform acquisition, an abnormal RF waveform that suddenly occurs should be collected for failure diagnostics. Therefore, we developed an abnormal RF waveform data acquisition (DAQ) system, which consists of the VME systems, a cache server, and a NoSQL database system, Apache Cassandra. When the VME system detects an abnormal RF waveform, it collects all related waveforms of the same shot. The waveforms are stored in Cassandra through the cache server. Before the installation to SACLA, we ensured the performance with a prototype system. In 2014, we installed the DAQ system into the injection part with five VME systems. In 2015, we will acquire waveforms from the low-level RF control system configured by 74 VME systems at the SACLA accelerator.  
poster icon Poster WEPGF014 [0.974 MB]  
WEPGF029 High Level Software Structure for the European XFEL LLRF System controls, FPGA, electron, software 1
  • Ch. Schmidt, V. Ayvazyan, J. Branlard, L. Butkowski, O. Hensler, M. Killenberg, M. Omet, S. Pfeiffer, K.P. Przygoda, H. Schlarb
    DESY, Hamburg, Germany
  • W. Cichalewski, F. Makowski
    TUL-DMCS, Łódź, Poland
  • A. Piotrowski
    FastLogic Sp. z o.o., Łódź, Poland
  The Low level RF system for the European XFEL is controlling the accelerating RF fields in order to meet the specifications of the electron bunch parameters. A hardware platform based on the MicroTCA.4 standard has been chosen, to realize a reliable, remotely maintainable and high performing integrated system. Fast data transfer and processing is done by field programmable gate arrays (FPGA) within the crate, controlled by a CPU via PCIe communication. In addition to the MTCA system, the LLRF comprises external supporting modules also requiring control and monitoring software. In this paper the LLRF system high level software used in E-XFEL is presented. It is implemented as a semi-distributed architecture of front end server instances in combination with direct FPGA communication using fast optical links. Miscellaneous server tasks have to be executed, e.g. fast data acquisition and distribution, adaptation algorithms and updating controller parameters. Furthermore the inter-server data communication and integration within the control system environment as well as the interface to other subsystems are described.  
WEPGF074 FPGA Firmware Framework for MTCA.4 AMC Modules interface, hardware, framework, FPGA 1
  • Ł. Butkowski, T. Kozak, B.Y. Yang
    DESY, Hamburg, Germany
  • P. Prędki
    TUL-DMCS, Łódź, Poland
  • R. Rybaniec
    Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland
  Many of the modules in specific hardware architectures use the same or similar communication interfaces and IO connectors. MicroTCA (MTCA.4) is one example of such a case. All boards: communicate with the central processing unit (CPU) over PCI Express (PCIe), send data to each other using Multi-Gigabit Transceivers (MGT), use the same backplane resources and have the same Zone3 IO or FPGA mezzanine card (FMC) connectors. All those interfaces are connected and implemented in Field Programmable Gate Array (FPGA) chips. It makes possible to separate the interface logic from the application logic. This structure allows to reuse already done firmware for one application and to create new application on the same module. Also, already developed code can be reused in new boards as a library. Proper structure allows the code to be reused and makes it easy to create new firmware. This paper will present structures of firmware framework and scripting ideas to speed up firmware development for MTCA.4 architecture. European XFEL control systems firmware, which uses the described framework, will be presented as example.  
poster icon Poster WEPGF074 [0.702 MB]