IPAC2017 - Classification: 06 Beam Instrumentation, Controls, Feedback and Operational Aspects / T27 Low Level RF

Paper	Title	Page
THOAA1	Development of a DLLRF Using Commercial uTCA Platform	3631
	A. Salom, E. Morales, F. Pérez ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
	The Digital LLRF of ALBA has been implemented using commercial cPCI boards with Virtex-4 FPGA, fast ADCs and fast DACs. The firmware of the FPGA is based on IQ demodulation technique and the main feed-back loops adjust the phase and amplitude of the cavity voltage and also the resonance frequency of the cavity. But the evolution of the market is moving towards uTCA technology and due to the interest of this technology by several labs, we have developed at ALBA a DLLRF using a HW platform based on uTCA commercial boards and Virtex-6 FPGA. The paper will present the development done and will compare it with respect the cPCI one.
	Slides THOAA1 [1.381 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THOAA1
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THOAA3	Installation and First Commissioning of the LLRF System for the European XFEL	3638
	J. Branlard, G. Ayvazyan, V. Ayvazyan, Ł. Butkowski, M. Fenner, M.K. Grecki, M. Hierholzer, M. Hoffmann, M. Killenberg, D. Kostin, D. Kühn, F. Ludwig, D.R. Makowski, U. Mavrič, M. Omet, S. Pfeiffer, H. Pryschelski, K.P. Przygoda, A.T. Rosner, R. Rybaniec, H. Schlarb, Ch. Schmidt, N. Shehzad, B. Szczepanski, G. Varghese, H.C. Weddig, R. Wedel, M. Wiencek, B.Y. Yang DESY, Hamburg, Germany W. Cichalewski, F. Makowski, A. Mielczarek, P. Perek TUL-DMCS, Łódź, Poland K. Czuba, P.K. Jatczak, T.P. Leśniak, K. Oliwa, D. Sikora, M. Urbański, W. Wierba Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland A.S. Nawaz TUHH, Hamburg, Germany
	The installation phase of the European X-ray free laser electron laser (XFEL) is finished, leaving place for its commissioning phase. This contribution summarizes the low-level radio frequency (LLRF) installation steps, illustrated with examples of its challenges and how they were addressed. The commissioning phase is also presented, with a special emphasis on the effort placed into developing LLRF automation tools to support the commissioning of such a large scale accelerator. The first results of the LLRF commissioning of the XFEL injector and first RF stations in the main linac are also given.
	Slides THOAA3 [15.800 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THOAA3
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THPAB095	Detuning Compensation in SC Cavities Using Kalman Filters	3938
	A. Ushakov, P. Echevarria, A. Neumann HZB, Berlin, Germany
	For CW driven superconducting cavities operating at small bandwidth, like in ERL or FEL light sources, it is mandatory to precisely control any source of detuning. Therefore, a Kalman [1] filter based approach was developed and implemented as FPGA firmware to act as the core part of a detuning compensation algorithm. It relies on a fit by a second order model to a measured transfer function of cavity's forced oscillations with damping, caused by piezo drives and data about observed current phase with some adjustable confidence rate. The initial data for this core is taken from field detection firmware on mTCA.4's SIS8300-L2 digitizer, transferred by low latency links to a carrier board equipped by piezo drive controller where the DSP processing by the Kalman algorithm performed. The processing is characterized by a 550 kHz rate in pipeline mode and occupies almost all DSP resources of the Spartan 6 FPGA chip. The experimental results of detuning compensating technique applied to a SC photoinjector cavity are presented in this contribution. Kalman, R. E. (1960): A New Approach to Linear Filtering and Prediction Problems, Transaction of the ASME, Journal of Basic Engineering, Pages 35-45.
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THPAB097	Phase Calibration of Synchrotron RF Signals	3945
	A. Andreev, H. Klingbeil TEMF, TU Darmstadt, Darmstadt, Germany H. Klingbeil, D.E.M. Lens GSI, Darmstadt, Germany
	In the scope of FAIR's scientific program higher beam intensities will be achieved and several new synchrotrons (including storage rings) are being built. The low-level RF (LLRF) systems of FAIR have to support multi-harmonic operations, barrier bucket generation and bunch compression in order to meet the desired beam quality requirements. All this imposes several requirements on the LLRF systems. For example the phase error of the gap voltage of a specific RF cavity must be less than 3 degrees. Thus, each individual component must have a better accuracy. The RF reference signals for the FAIR synchrotron RF cavity systems are generated by direct digital synthesis (DDS). Four so-called Group DDS modules are mounted in one crate. In the supply rooms, the reference signals of such a crate are then distributed to local cavity LLRF systems. Therefore, the precise phase calibration of Group DDS modules is of importance. A phase calibration method with respect to the absolute phases of DDS modules defined by means of the FAIR Bunch Phase Timing System (BuTiS) is developed, and its precision is under evaluation.
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THPAB098	Test Setup for Automated Barrier Bucket Signal Generation	3948
	K. Groß, D. Domont-Yankulova, J. Harzheim, H. Klingbeil TEMF, TU Darmstadt, Darmstadt, Germany M. Frey, H. Klingbeil GSI, Darmstadt, Germany
	Funding: Work supported by the German Federal Ministry of Education and Research (BMBF) under the project 05P15RDRBA. For sophisticated beam manipulation several ring accelerators at FAIR and GSI like the main synchrotron SIS100 and the ESR will be equipped with barrier bucket systems. Hence, the associated LLRF has to be applicable to different RF systems, with respect to the cavity layout and the power amplifier used, as well as to variable repetition rates and amplitudes. Since already the first barrier bucket pulse of a long sequence has to meet certain minimum demands, an open-loop control on the basis of calibration data is foreseen. Closed-loop control is required to improve the signal quality during a sequence of pulses and to adapt to changing conditions like temperature drifts. A test setup was realized that allows controlling the signal generator, reading out the oscilloscope as well as processing the collected data. Frequency and time domain methods can be implemented to approach the dynamics of the RF system successively and under operating conditions, i.e. generating single sine pulses. The setup and first results from measurements are presented as a step towards automated acquisition of calibration data and iterative improvement of the same.
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THPAB099	Challenges of a Stable ERL Operation Concerning the Digital RF Control System of the S-DALINAC	3951
	M. Steinhorst, M. Arnold, U. Bonnes, C. Burandt, N. Pietralla TU Darmstadt, Darmstadt, Germany T. Kürzeder HIM, Mainz, Germany
	Funding: Supported by the DFG through RTG 2128. The superconducting recirculating electron linear accelerator S-DALINAC is the central large-scale research device of the institute for nuclear physics at the TU Darmstadt in Germany. In 2015/2016 the S-DALINAC received an upgrade to three recirculations. The new beam line enables in addition to higher maximum energies the possibility to operate the S-DALINAC as an Energy Recovery Linac (ERL). Therefore the current rf control system encounters new requirements for ERL operation. Since 2010 a digital rf control system is successfully used for the control of the superconducting cavities. This system was not built and optimized for the control of an ERL. This contribution is discussing the expected challenges of an ERL operation regarding the existing digital rf control system.
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THPAB100	On the Impact of Empty Buckets on the Ferrite Cavity Control Loop Dynamics in High Intensity Hadron Synchrotrons	3954
	D. Mihailescu Stoica, D. Domont-Yankulova Technische Universität Darmstadt (TU Darmstadt, RMR), Darmstadt, Germany D. Domont-Yankulova, H. Klingbeil TEMF, TU Darmstadt, Darmstadt, Germany H. Klingbeil, D.E.M. Lens GSI, Darmstadt, Germany
	Funding: Supported by the Helmholtz Graduate School for Hadron and Ion Research Due to technical reasons two of ten buckets have to stay empty in the planned SIS100 synchrotron at the GSI Helmholtzzentrum für Schwerionenforschung. The planned low level RF control systems consist of linear P and PI type controllers. These are responsible to maintain a desired phase and amplitude of the gap voltage. In addition the cavity is controlled to follow a prescribed resonance frequency ramp. In SIS100 the acceleration will be performed by ferrite cavities with comparatively small quality factors. Therefore, effects resulting from transient beam loading have to be expected. Influences due to empty buckets are analysed in the frequency domain and particle tracking simulations are carried out to estimate the effect on the overall system with particular consideration of emittance growth and particle loss.
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THPAB103	On-Line RF Amplitude and Phase Calibration	3957
	M.K. Grecki, V. Ayvazyan, J. Branlard, M. Hoffmann, M. Omet, H. Schlarb, Ch. Schmidt DESY, Hamburg, Germany
	The accelerating RF field has crucial importance on the beam properties. It is not only used just to accelerate particles but also to shape the bunches at bunch compressors. It is really important to control and measure the field as seen by the beam while usually only indirect (not using the beam) field measurements are available*. Since they are affected by many contributions the measurements must be always calibrated to the beam. Usually this calibration is performed at special operating conditions that prevents normal operation of the accelerator. During normal operation the calibrations is assumed to not drift which is certainly not perfectly true and introduce some control errors. The paper shows how to extract the RF-beam calibration from RF signals during normal operating condition (when RF feed-back, beam loading compensation, learning feed-forward etc. are active). All the algorithms and computations were performed on signals recorded at FLASH accelerator but the main idea is general and can be used at other locations as well.
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THPAB106	Experience with Single Cavity and Piezo Controls for Short, Long Pulse and CW Operation	3966
	K.P. Przygoda, V. Ayvazyan, R. Rybaniec, H. Schlarb, Ch. Schmidt, J.K. Sekutowicz DESY, Hamburg, Germany P. Echevarria HZB, Berlin, Germany
	We present a compact RF control system for SCRF single cavities based on MicroTCA.4 equipped with specialized advanced mezzanine cards (AMCs) and rear transition modules (RTMs). To sense the RF signals from the cavity and to drive the high power source, a DRTM-DWC8VM1 module is used equipped with 8 analog field detectors and one RF vector modulator. Fast cavity frequency tuning is achieved by piezo-actuators attached to the cavity and a RTM piezo-driver module (DRTM-PZT4). Data processing of the RF signals and the real-time control algorithms are implemented on a Virtex-6 FPGA and a Spartan FPGAs within two AMCs (SIS8300-L2V2 and DAMC-FMC20). The compact single cavity control system was tested at Cryo Module Test Bench (CMTB) at DESY. Software and firmware were developed to support all possible modes, the short pulse (SP), the long pulse (LP) and CW operation mode with duty cycles ranging from 1 % to 100%. The SP mode used a high power multi-beam klystron at low QL ~3·10⁶. For the LP mode (up to 50% duty cycle) and the CW mode a 120 kW IOT tube was used at QL up to 1.5·10⁷. Within this paper we present the achieved performance and report on the operation experience on such system.
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THPAB114	Operation of LLRF Control Systems in SuperKEKB Phase-1 Commissioning	3986
	T. Kobayashi, K. Akai, K. Ebihara, A. Kabe, K. Nakanishi, M. Nishiwaki, J.-I. Odagiri, S.I. Yoshimoto KEK, Ibaraki, Japan K. Hirosawa Sokendai, Ibaraki, Japan
	First beam commissioning of SuperKEKB (Phase-1), which had started in February 2016 and continued until the end of June, has been successfully accomplished. Target beam current for Phase-1 needed for sufficient vacuum scrubbing was achieved in both 7-GeV electron and 4-GeV positron rings. This presentation summarize the operation results related to low level RF (LLRF) control issues during the Phase-1 commissioning, including the system tuning, the coupled bunch instability and the bunch gap transient effect. RF system of SuperKEKB consists of about thirty klystron stations in both rings. Newly developed LLRF control system, which is composed of recent digital technique, is applied to the nine stations among the thirty for Phase-1. The RF reference signal distribution system has been also upgraded for SuperKEKB. These new systems worked well without serious problem and they contributed to smooth progress of the commissioning. The old existing systems, which had been used in the KEKB operation, were still reused for the most stations, and they also worked as soundly as performed in the KEKB operation.
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THPAB115	Development of a Longitudinal Feedback System for Coupled Bunch Instabilities Caused by the Accelerating Mode at Superkekb	3989
	K. Hirosawa, K. Akai, E. Ezura, T. Kobayashi, K. Nakanishi, M. Nishiwaki, S.I. Yoshimoto KEK, Ibaraki, Japan
	SuperKEKB is an asymmetric energy electron-positron circular collider. Phase-I commissioning was operated from February to June in 2016. The purpose of this accelerator is to aim at the higher luminosity than KEKB, so a larger beam current is made for it. In the future plan, beam currents in the electron and positron rings will be increased to 2.6A and 3.6A, respectively. As we consider beam dynamics in the storage ring, higher mode instability associated with the accelerating mode will be caused by a large beam current. Especially the target instability of this study is called μ=-2 mode Coupled Bunch Instability. To suppress it, we developed new feedback components for longitudinal coupled bunch instability. We have same mechanism feedback components for KEKB, but it supports only μ=-1 mode instability. Since a large current makes μ=-1 mode instability big, there is a possibility that suppression is difficult only by using KEKB components. In order to deal with this problem, new components we developed support μ=-1, -2, and -3 mode instabilities, and we improved the performance and usability as compared to existing components. We schedule studies using a beam at Phase-II.
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THPAB116	Evaluation of Digital LLRF Control System Performance at STF in KEK	3992
SUSPSIK087	use link to see paper's listing under its alternate paper code
	S.B. Wibowo, N. Liu Sokendai, Ibaraki, Japan T. Matsumoto, S. Michizono, T. Miura, F. Qiu KEK, Ibaraki, Japan
	The Superconducting RF Test Facility (STF) at the High Energy Accelerator Research Organization (KEK) was built for research and development of the International Linear Collider (ILC). Several digital low-level radio frequency (LLRF) control systems were developed at the STF. The purposes of these developments are to construct a minimal configuration of the ILC LLRF system and achieve the amplitude and phase stability of the accelerating field in the superconducting accelerator. Evaluations of digital LLRF control systems were conducted during the conditioning of eight superconducting cavities performed between October and November 2016. The digital LLRF control system configured for ILC was demonstrated and the performance fulfilled the required stability criteria of the accelerating field in the ILC. These evaluations are reported in this paper.
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THPAB117	Development of a New LLRF System Based on MicroTCA.4 for the SPring-8 Storage Ring	3996
	T. Ohshima, H. Ego, N. Hosoda, H. Maesaka RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan T. Fukui RIKEN SPring-8 Center, Innovative Light Sources Division, Hyogo, Japan M. Ishii JASRI/SPring-8, Hyogo-ken, Japan
	SPring-8 is a 3rd generation synchrotron radiation facility, which has been operated since 1997. The analog-circuit-based rf modules now in use at the storage ring are obsolete and hard to be maintained. The renewal of them with modern digital ones is underway and the developed LLRF system will be used for the operation of SPring-8-II. We built an amplitude and phase stabilizing system with commercial MicroTCA.4 modules. A motor driver controlled through EtherCAT was newly adapted to the cavity tuner. The system was implemented to the high power rf test stand which consists of a 1 MW klystron, a circulator, and a 508.58 MHz cavity. The rf power was successfully regulated to keep the cavity voltage with an amplitude deviation of less than 0.1% and a phase stability of less than 0.1 degree in rms. We are also developing new MTCA.4 modules: a digitizer AMC having sampling rate of 370 MHz and 16bit resolution, and a signal conditioning RTM. These modules are used for under-sampling rf detection achieving simple composition and more robustness to the ambient parameter changes. We will start installation of the digital system to one of four rf stations in the storage ring in summer 2017.
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THPAB123	Low Level RF Control System Architecture OF IR-FEL	4014
	B. Du, G. Huang, L. Lin, W. Liu, Z.R. Zhou USTC/NSRL, Hefei, Anhui, People's Republic of China
	Infrared free electron laser (IR-FEL) is one type of laser driven by accelerator and generated by undulator. It is built by National Synchrotron Radiation Laboratory (NSRL). Compared to synchrotron radiation light source, it have much higher demand of beam quality. Low level RF control system (LLRF) need to reach higher controlled accuracy corresponded to the demand. Accelerating structure which contains one pre-buncher, one buncher and two accelerating tube can accelerate beam to 60MeV. Frequency distribution system use direct digital synthesizer technology to generate 5 signal of different frequency. LLRF system detect 8 channels signal, one for control loop, and the others for monitor and interlock. The hardware contain MTCA.4 architecture which is advanced in global; RF board for downconverter and IQ modulation output; DSP board for sampling, controller and transmission.
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THPAB124	DSP Frame and Algorithm of LLRF of IR-FEL	4017
	B. Du, G. Huang, L. Lin, W. Liu, Z.R. Zhou USTC/NSRL, Hefei, Anhui, People's Republic of China
	Infrared Free Electron Laser (IR-FEL) use linear accelerator to accelerate electron to relative speed and then generate simulated radiation of infrared wavelength by periodic magnetic field of undulator. The amplitude and phase of microwave field need to be controlled precisely by low level RF control system (LLRF) to meet the high quality demand of electron from undulator. This paper mainly introduce the digital signal processing frame and feedback algorithm. Four times frequency sampling can realize IQ demodulation precisely and reduce DC offset, amplitude sampling error is less than 0.075% and phase sampling error is less than 0.1°. Pipeline CORDIC can calculate amplitude and phase by parallel processing and shift operation. Phase calculating accuracy reach 0.0005° when iteration count is 18. FIR filter is used to improve frequency selected performance. Feedback loop use digital PI controller to adjust system output.
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THPAB129	Contribution to the ESS LLRF System by Polish Electronic Group	4026
	J. Szewiński, M. Gosk, Z. Gołębiewski, P. Krawczyk, I.M. Kudla NCBJ, Świerk/Otwock, Poland A. Abramowicz, K. Czuba, M.G. Grzegrzolka, I. Rutkowski Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland W. Cichalewski, D.R. Makowski, A. Napieralski TUL-DMCS, Łódź, Poland
	Funding: Described work will be done as a part of polish in-kind contribution, granted by the Polish Ministry of Science and Higher Education in the decision number DIR/WK/2016/03. Development of the LLRF system at ESS is coordinated by the Lund University, but part of it, LLRF systems for M-Beta and H-Beta sections, will be delivered within in-kind contribution from Poland. This document will describe the scope of work, work plan, and technical details of the selected components of the M-Beta and H-Beta LLRF systems sections. Described contribution will be made by the Polish Electronic Group (PEG), a consortium of three scientific units. LLRF system for ESS will be made of both, commercially available components and components designed specially for this project, and those last ones will be presented and described here. Except the technical details, the organizational aspects, such as schedule, project management or quality control, will be presented as well.
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THPAB131	Test of the Feedback and Feedforward Control Loop for Digital LLRF System of 1 MeV/n RFQ	4028
	H.S. Jeong, Y.-S. Cho, H.S. Kim, J.H. Kim, S.G. Kim, H.-J. Kwon, Y.G. Song Korea Atomic Energy Research Institute (KAERI), Gyeongbuk, Republic of Korea
	Funding: This work has been supported through KOMAC (Korea of Multi-purpose Accelerator Complex) operation fund of KAERI by MSIP (Ministry of Science, ICT and Future Planning) KOMAC (Korea Multi-purpose Accelerator Complex) has a plan to develop the multipurpose ion irradiation system. This system includes the ion source, LEBT, RFQ and MEBT systems to transport ion particles to the target. In particular, the RFQ (Radio Frequency Quadrupole) system should receive 200 MHz RF within 1 % amplitude error stability. To supply stable 200 MHz RF signal to the RFQ cavity, the LLRF (Low-Level Radio Frequency) system should be controlled through a control system which implemented using commercial digital board. This 1 MeV/n RFQ LLRF system has a concept to minimize the number of the analog components for minimizing the control error. For this, the FPGA (Field Programmable Gate Array) in the digital board will control the frequency of the output sinusoidal signal. In addition, this LLRF system applied the direct sampling, Non-IQ sampling, direct RF generation and fast IQ set update rate algorithm. In this presentation, the LLRF PI control and feed-forward control logic test using 200 MHz dummy cavity will be described. LLRF, direct sampling, Non-IQ, RFQ, control loop, feedback, feedforward
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THPAB134	Latest Development of the ALBA DLLRF	4034
	A. Salom, B. Bravo, M. Broseta, E. Morales, J.R. Ocampo, F. Pérez, P. Solans ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
	The Digital LLRF of ALBA has been implemented using commercial cPCI boards with Virtex-4 FPGA, fast ADCs and fast DACs. The firmware of the FPGA is based on IQ demodulation technique and the main feed-back loops adjust the phase and amplitude of the cavity voltage and also the resonance frequency of the cavity. This paper summarizes the latest LLRF developments done to improve performance of the RF systems and beam stability, including feed-forward loops based on phase modulation to compensate disturbances due to RF trip, beam loading compensation and Power Unbalance Compensation Loop for RF amplifiers Combination.
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THPAB135	Digital LLRF for MAX IV	4037
	A. Salom, F. Pérez ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain Å. Andersson, R. Lindvall, L. Malmgren, A.M. Milan, A.M. Mitrovic MAX IV Laboratory, Lund University, Lund, Sweden
	The MAX IV facility consists of a 3 GeV Storage Ring(SR), a 1.5 GeV SR, and a linear accelerator (fed by two guns) that serves as a full-energy injector to the rings, but also as a driver for the Short Pulse Facility. The RF systems of the two SRs work at 100MHz. There are 6 normal conducting capacity loaded accelerating cavities and three Landau passive cavities in the 3GeV SR. In the 1.5GeV SR there are two accelerating cavities and two Landau cavities with the same characteristics. Each of these cavities is fed by a modular 60kW SSA. In the 3 GeV SR the power will be doubled by adding a second SSA when required. A digital Low Level RF system has been developed using commercial uTCA boards, with a Virtex-6 FPGA mother board (Perseus 601X) and two double stack FMC boards with fast ADCs and DACs. The large capabilities of state-of-the-art FPGAs allowed including the control of two normal conducing cavities and two landau cavities in one single LLRF system, reducing the development costs. Other utilities like the handling of fast interlocks and post-mortem analysis were also added to this system. This paper summarizes the main capabilities and performance of this DLLRF.
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THPAB141	Control and Operation of a Wideband RF System in CERN's PS Booster	4050
	M.E. Angoletta, S.C.P. Albright, A. Findlay, M. Haase, M. Jaussi, J.C. Molendijk, M.M. Paoluzzi, J. Sanchez-Quesada CERN, Geneva, Switzerland
	A prototype wideband High-Level RF (HLRF) sys-tem based on Finemet metal alloy has been installed in CERN's PS Booster (PSB) Ring 4 in 2012, within the frame of the LHC Injectors Upgrade (LIU) project. A digital Low-Level RF (LLRF) system was used to control the HLRF system to ascertain the capabilities of the combined system, especially under heavy beam loading. The testing campaign was satisfactory and in 2015 the CERN management decided to replace all ferrite-based systems with Finemet ones for the PS Booster restart in 2020. This paper describes the LLRF features implemented for operating the wideband HLRF system and the main beam results obtained. Hints on the LLRF evolution in view of the PSB HLRF renovation are also given.
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THPAB142	Initial Beam Results of CERN ELENA's Digital Low-Level RF System	4054
	M.E. Angoletta, S.C.P. Albright, S. Energico, S. Hancock, M. Jaussi, A.J. Jones, J.C. Molendijk, M.M. Paoluzzi, J. Sanchez-Quesada CERN, Geneva, Switzerland
	The Extra Low ENergy Antiproton (ELENA) decelerator is under commissioning at CERN. This decelerator is equipped with a new digital low-level RF (LLRF) system, in-house developed and belonging to the LLRF family already deployed in CERN's PS Booster and Low Energy Ion Ring (LEIR) synchrotrons. New features to adapt it to the demanding requirements of ELENA's operation include new, low noise ADC daughtercards and a fixed-frequency clocking scheme. This paper gives an overview of the LLRF system; initial beam results are also shown together with hints on the future system upgrade.
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THPAB143	Operational Experience With the New Digital Low-Level RF System for CERN's PS Booster	4058
	M.E. Angoletta, S.C.P. Albright, A. Findlay, S. Hancock, M. Jaussi, J.C. Molendijk, J. Sanchez-Quesada CERN, Geneva, Switzerland
	The four rings of CERN's PS Booster have been equipped in 2014 with a new digital low-level RF (LLRF) system based upon a new, in-house developed LLRF family. This is a second-generation LLRF family that has been since then deployed on other synchrotrons. The paper provides an overview of the system's commissioning and first years of operation. In particular, an overview is given of the main system features and capabilities, such as beam loops and longitudinal beam blowup implementation. Operational improvements with respect to the previous, analogue digital LLRF are also mentioned, together with the planned system evolution to satisfy new requirements.
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THPAB144	The New LEIR Digital Low-Level RF System	4062
	M.E. Angoletta, S.C.P. Albright, A. Findlay, M. Haase, S. Hancock, M. Jaussi, J.C. Molendijk, M.M. Paoluzzi, J. Sanchez-Quesada CERN, Geneva, Switzerland
	CERN's Low Energy Ion Ring (LEIR) low-level RF (LLRF) system has been successfully upgraded in 2016 to the new digital, LLRF family for frequency-sweeping synchrotrons developed at CERN. For LEIR it implements not only beam loops but also the voltage and phase loops required for the control of two Finemet-based High-Level RF (HLRF) systems. This paper gives an overview of the system and of new requirements implemented, such as the parallel operation of two HLRF systems. Beam results for the 2016 lead ions run are also shown.
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THPAB148	DIGITAL LOW LEVEL RF CONTROL SYSTEM FOR THE TAIWAN PHOTON SOURCE	4077
	F.Y. Chang, L.-H. Chang, M.H. Chang, L.J. Chen, F.-T. Chung, M.-C. Lin, Z.K. Liu, C.H. Lo, C.L. Tsai, Ch. Wang, M.-S. Yeh, T.-C. Yu NSRRC, Hsinchu, Taiwan
	The Taiwan Photon Source (TPS) is a 3 GeV, 500 mA, 499.65 MHz, 3rd generation synchrotron light source at NSRRC. To achieve the requirements of system flexibil-ity, fault diagnosis, precise control and high noise reduc-tion, a digital low level RF (DLLRF) control system based on Field Programmable Gate Array (FPGA) was developed. The communication interface is based on Raspberry Pi. The feedback loop performance of the control system was tested on the booster of the Taiwan Photon Source (TPS) with 950 kV gap voltage.
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THPAB150	Input Output Controller of Digital Low Level RF System in NSRRC	4083
	Z.K. Liu, F.Y. Chang, L.-H. Chang, M.H. Chang, L.J. Chen, F.-T. Chung, M.-C. Lin, C.H. Lo, C.L. Tsai, Ch. Wang, M.-S. Yeh, T.-C. Yu NSRRC, Hsinchu, Taiwan
	Low Level Radio Frequency (LLRF) systems operating at NSRRC are based on analog technology and are used both at the Taiwan Light Source and the Taiwan Photon Source. In order to have better RF field stability, a new digital LLRF system based on Field Programmable Gate Array (FPGA) was developed. A card-sized single-board computer is used as the input/output controller of the digital LLRF system and its design and implementation with EPICS applications are reported here.
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THPAB152	Digital Low Level RF Systems for Diamond Light Source	4089
	P. Gu, C. Christou, P. Hamadyk, D. Spink, I.S. Uzun DLS, Oxfordshire, United Kingdom E. Morales, F. Pérez, A. Salom ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
	Analogue low level RF (LLRF) systems have been used to date for both Diamond storage ring and booster RF cavities. They have been in operation for nearly ten years without a major problem. However, digital LLRF can offer new desirable functionalities such as fast data logging, 'probe blip' blockage and automation of routine tasks. Better performance is also envisaged with up to date hardware. A digital LLRF system has been developed with Alba Synchrotron as a common platform for the storage ring and booster, including superconducting and normal conducting RF cavities. The new digital LLRF is based on Virtex6 FPGA and fast ADCs and DACs. One system has been built and verified in the Diamond booster with beam. The design will be implemented for all other Diamond RF cavities.
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THPVA152	Performance of ATCA LLRF System at LCLS	4817
	J.M. D'Ewart, J.C. Frisch, B. Hong, K.H. Kim, J.J. Olsen, D. Van Winkle SLAC, Menlo Park, California, USA
	Funding: Work supported by Department of Energy contract DE-AC02-76SF00515. The low level RF control for the SLAC LINAC is being upgraded to provide improved performance and maintainability. The new LLRF system is based on the SLAC ATCA common platform hardware. RF control is achieved through a high performance FPGA based DDS/DDC system. The signal processing is designed to be phase insensitive, allowing the use of modest performance on-board digitizer clock and LO. The prototype LLRF control system was installed and used to operate RF station 28-2 in LCLS-I. Design details and prototype performance results will be presented.
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THPVA154	LLRF Hardware Testbench	4821
	J.A. Diaz Cruz, S. Biedron, S.V. Milton CSU, Fort Collins, Colorado, USA A.L. Benwell, A. Ratti SLAC, Menlo Park, California, USA
	With continual advances and the development of new technologies, such as superconducting cavities, particle accelerators have become more complex. New accelerator designs have more demanding stability requirements for the cavity RF fields, up to 0.01% in amplitude and 0.01' in phase for hundreds of cavities in Continuous Wave (CW) operation. Compensating for disturbances from mechanical resonances, microphonics, natural couplings and unwanted channel crosstalk is a challenge for the Low Level Radio Frequency (LLRF) control systems. For the upgrade to the Linac Coherent Light Source (LCLS-II) at SLAC, a high performance LLRF control system is being designed and developed to drive the Solid State Amplifiers (SSA) and control the cavity fields within specifications. The different components of the LLRF hardware have been designed, constructed and tested separately. Here, we describe a test environment, still under development, for integration, characterization and qualification of the LLRF system with all the LLRF hardware integrated in a single prototype rack.
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Paper

Title

Page

Development of a DLLRF Using Commercial uTCA Platform

3631

A. Salom, E. Morales, F. Pérez
ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain

The Digital LLRF of ALBA has been implemented using commercial cPCI boards with Virtex-4 FPGA, fast ADCs and fast DACs. The firmware of the FPGA is based on IQ demodulation technique and the main feed-back loops adjust the phase and amplitude of the cavity voltage and also the resonance frequency of the cavity. But the evolution of the market is moving towards uTCA technology and due to the interest of this technology by several labs, we have developed at ALBA a DLLRF using a HW platform based on uTCA commercial boards and Virtex-6 FPGA. The paper will present the development done and will compare it with respect the cPCI one.

Slides THOAA1 [1.381 MB]

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THOAA3

Installation and First Commissioning of the LLRF System for the European XFEL

3638

J. Branlard, G. Ayvazyan, V. Ayvazyan, Ł. Butkowski, M. Fenner, M.K. Grecki, M. Hierholzer, M. Hoffmann, M. Killenberg, D. Kostin, D. Kühn, F. Ludwig, D.R. Makowski, U. Mavrič, M. Omet, S. Pfeiffer, H. Pryschelski, K.P. Przygoda, A.T. Rosner, R. Rybaniec, H. Schlarb, Ch. Schmidt, N. Shehzad, B. Szczepanski, G. Varghese, H.C. Weddig, R. Wedel, M. Wiencek, B.Y. Yang
DESY, Hamburg, Germany
W. Cichalewski, F. Makowski, A. Mielczarek, P. Perek
TUL-DMCS, Łódź, Poland
K. Czuba, P.K. Jatczak, T.P. Leśniak, K. Oliwa, D. Sikora, M. Urbański, W. Wierba
Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland
A.S. Nawaz
TUHH, Hamburg, Germany

The installation phase of the European X-ray free laser electron laser (XFEL) is finished, leaving place for its commissioning phase. This contribution summarizes the low-level radio frequency (LLRF) installation steps, illustrated with examples of its challenges and how they were addressed. The commissioning phase is also presented, with a special emphasis on the effort placed into developing LLRF automation tools to support the commissioning of such a large scale accelerator. The first results of the LLRF commissioning of the XFEL injector and first RF stations in the main linac are also given.

Slides THOAA3 [15.800 MB]

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THPAB095

Detuning Compensation in SC Cavities Using Kalman Filters

3938

A. Ushakov, P. Echevarria, A. Neumann
HZB, Berlin, Germany

For CW driven superconducting cavities operating at small bandwidth, like in ERL or FEL light sources, it is mandatory to precisely control any source of detuning. Therefore, a Kalman [1] filter based approach was developed and implemented as FPGA firmware to act as the core part of a detuning compensation algorithm. It relies on a fit by a second order model to a measured transfer function of cavity's forced oscillations with damping, caused by piezo drives and data about observed current phase with some adjustable confidence rate. The initial data for this core is taken from field detection firmware on mTCA.4's SIS8300-L2 digitizer, transferred by low latency links to a carrier board equipped by piezo drive controller where the DSP processing by the Kalman algorithm performed. The processing is characterized by a 550 kHz rate in pipeline mode and occupies almost all DSP resources of the Spartan 6 FPGA chip. The experimental results of detuning compensating technique applied to a SC photoinjector cavity are presented in this contribution.
Kalman, R. E. (1960): A New Approach to Linear Filtering and Prediction Problems, Transaction of the ASME, Journal of Basic Engineering, Pages 35-45.

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THPAB097

Phase Calibration of Synchrotron RF Signals

3945

A. Andreev, H. Klingbeil
TEMF, TU Darmstadt, Darmstadt, Germany
H. Klingbeil, D.E.M. Lens
GSI, Darmstadt, Germany

In the scope of FAIR's scientific program higher beam intensities will be achieved and several new synchrotrons (including storage rings) are being built. The low-level RF (LLRF) systems of FAIR have to support multi-harmonic operations, barrier bucket generation and bunch compression in order to meet the desired beam quality requirements. All this imposes several requirements on the LLRF systems. For example the phase error of the gap voltage of a specific RF cavity must be less than 3 degrees. Thus, each individual component must have a better accuracy. The RF reference signals for the FAIR synchrotron RF cavity systems are generated by direct digital synthesis (DDS). Four so-called Group DDS modules are mounted in one crate. In the supply rooms, the reference signals of such a crate are then distributed to local cavity LLRF systems. Therefore, the precise phase calibration of Group DDS modules is of importance. A phase calibration method with respect to the absolute phases of DDS modules defined by means of the FAIR Bunch Phase Timing System (BuTiS) is developed, and its precision is under evaluation.

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THPAB098

Test Setup for Automated Barrier Bucket Signal Generation

3948

K. Groß, D. Domont-Yankulova, J. Harzheim, H. Klingbeil
TEMF, TU Darmstadt, Darmstadt, Germany
M. Frey, H. Klingbeil
GSI, Darmstadt, Germany

Funding: Work supported by the German Federal Ministry of Education and Research (BMBF) under the project 05P15RDRBA.
For sophisticated beam manipulation several ring accelerators at FAIR and GSI like the main synchrotron SIS100 and the ESR will be equipped with barrier bucket systems. Hence, the associated LLRF has to be applicable to different RF systems, with respect to the cavity layout and the power amplifier used, as well as to variable repetition rates and amplitudes. Since already the first barrier bucket pulse of a long sequence has to meet certain minimum demands, an open-loop control on the basis of calibration data is foreseen. Closed-loop control is required to improve the signal quality during a sequence of pulses and to adapt to changing conditions like temperature drifts. A test setup was realized that allows controlling the signal generator, reading out the oscilloscope as well as processing the collected data. Frequency and time domain methods can be implemented to approach the dynamics of the RF system successively and under operating conditions, i.e. generating single sine pulses. The setup and first results from measurements are presented as a step towards automated acquisition of calibration data and iterative improvement of the same.

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THPAB099

Challenges of a Stable ERL Operation Concerning the Digital RF Control System of the S-DALINAC

3951

M. Steinhorst, M. Arnold, U. Bonnes, C. Burandt, N. Pietralla
TU Darmstadt, Darmstadt, Germany
T. Kürzeder
HIM, Mainz, Germany

Funding: Supported by the DFG through RTG 2128.
The superconducting recirculating electron linear accelerator S-DALINAC is the central large-scale research device of the institute for nuclear physics at the TU Darmstadt in Germany. In 2015/2016 the S-DALINAC received an upgrade to three recirculations. The new beam line enables in addition to higher maximum energies the possibility to operate the S-DALINAC as an Energy Recovery Linac (ERL). Therefore the current rf control system encounters new requirements for ERL operation. Since 2010 a digital rf control system is successfully used for the control of the superconducting cavities. This system was not built and optimized for the control of an ERL. This contribution is discussing the expected challenges of an ERL operation regarding the existing digital rf control system.

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THPAB100

On the Impact of Empty Buckets on the Ferrite Cavity Control Loop Dynamics in High Intensity Hadron Synchrotrons

3954

D. Mihailescu Stoica, D. Domont-Yankulova
Technische Universität Darmstadt (TU Darmstadt, RMR), Darmstadt, Germany
D. Domont-Yankulova, H. Klingbeil
TEMF, TU Darmstadt, Darmstadt, Germany
H. Klingbeil, D.E.M. Lens
GSI, Darmstadt, Germany

Funding: Supported by the Helmholtz Graduate School for Hadron and Ion Research
Due to technical reasons two of ten buckets have to stay empty in the planned SIS100 synchrotron at the GSI Helmholtzzentrum für Schwerionenforschung. The planned low level RF control systems consist of linear P and PI type controllers. These are responsible to maintain a desired phase and amplitude of the gap voltage. In addition the cavity is controlled to follow a prescribed resonance frequency ramp. In SIS100 the acceleration will be performed by ferrite cavities with comparatively small quality factors. Therefore, effects resulting from transient beam loading have to be expected. Influences due to empty buckets are analysed in the frequency domain and particle tracking simulations are carried out to estimate the effect on the overall system with particular consideration of emittance growth and particle loss.

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THPAB103

On-Line RF Amplitude and Phase Calibration

3957

M.K. Grecki, V. Ayvazyan, J. Branlard, M. Hoffmann, M. Omet, H. Schlarb, Ch. Schmidt
DESY, Hamburg, Germany

The accelerating RF field has crucial importance on the beam properties. It is not only used just to accelerate particles but also to shape the bunches at bunch compressors. It is really important to control and measure the field as seen by the beam while usually only indirect (not using the beam) field measurements are available*. Since they are affected by many contributions the measurements must be always calibrated to the beam. Usually this calibration is performed at special operating conditions that prevents normal operation of the accelerator. During normal operation the calibrations is assumed to not drift which is certainly not perfectly true and introduce some control errors. The paper shows how to extract the RF-beam calibration from RF signals during normal operating condition (when RF feed-back, beam loading compensation, learning feed-forward etc. are active). All the algorithms and computations were performed on signals recorded at FLASH accelerator but the main idea is general and can be used at other locations as well.

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THPAB106

Experience with Single Cavity and Piezo Controls for Short, Long Pulse and CW Operation

3966

K.P. Przygoda, V. Ayvazyan, R. Rybaniec, H. Schlarb, Ch. Schmidt, J.K. Sekutowicz
DESY, Hamburg, Germany
P. Echevarria
HZB, Berlin, Germany

We present a compact RF control system for SCRF single cavities based on MicroTCA.4 equipped with specialized advanced mezzanine cards (AMCs) and rear transition modules (RTMs). To sense the RF signals from the cavity and to drive the high power source, a DRTM-DWC8VM1 module is used equipped with 8 analog field detectors and one RF vector modulator. Fast cavity frequency tuning is achieved by piezo-actuators attached to the cavity and a RTM piezo-driver module (DRTM-PZT4). Data processing of the RF signals and the real-time control algorithms are implemented on a Virtex-6 FPGA and a Spartan FPGAs within two AMCs (SIS8300-L2V2 and DAMC-FMC20). The compact single cavity control system was tested at Cryo Module Test Bench (CMTB) at DESY. Software and firmware were developed to support all possible modes, the short pulse (SP), the long pulse (LP) and CW operation mode with duty cycles ranging from 1 % to 100%. The SP mode used a high power multi-beam klystron at low QL ~3·10⁶. For the LP mode (up to 50% duty cycle) and the CW mode a 120 kW IOT tube was used at QL up to 1.5·10⁷. Within this paper we present the achieved performance and report on the operation experience on such system.

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THPAB114

Operation of LLRF Control Systems in SuperKEKB Phase-1 Commissioning

3986

T. Kobayashi, K. Akai, K. Ebihara, A. Kabe, K. Nakanishi, M. Nishiwaki, J.-I. Odagiri, S.I. Yoshimoto
KEK, Ibaraki, Japan
K. Hirosawa
Sokendai, Ibaraki, Japan

First beam commissioning of SuperKEKB (Phase-1), which had started in February 2016 and continued until the end of June, has been successfully accomplished. Target beam current for Phase-1 needed for sufficient vacuum scrubbing was achieved in both 7-GeV electron and 4-GeV positron rings. This presentation summarize the operation results related to low level RF (LLRF) control issues during the Phase-1 commissioning, including the system tuning, the coupled bunch instability and the bunch gap transient effect. RF system of SuperKEKB consists of about thirty klystron stations in both rings. Newly developed LLRF control system, which is composed of recent digital technique, is applied to the nine stations among the thirty for Phase-1. The RF reference signal distribution system has been also upgraded for SuperKEKB. These new systems worked well without serious problem and they contributed to smooth progress of the commissioning. The old existing systems, which had been used in the KEKB operation, were still reused for the most stations, and they also worked as soundly as performed in the KEKB operation.

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THPAB115

Development of a Longitudinal Feedback System for Coupled Bunch Instabilities Caused by the Accelerating Mode at Superkekb

3989

K. Hirosawa, K. Akai, E. Ezura, T. Kobayashi, K. Nakanishi, M. Nishiwaki, S.I. Yoshimoto
KEK, Ibaraki, Japan

SuperKEKB is an asymmetric energy electron-positron circular collider. Phase-I commissioning was operated from February to June in 2016. The purpose of this accelerator is to aim at the higher luminosity than KEKB, so a larger beam current is made for it. In the future plan, beam currents in the electron and positron rings will be increased to 2.6A and 3.6A, respectively. As we consider beam dynamics in the storage ring, higher mode instability associated with the accelerating mode will be caused by a large beam current. Especially the target instability of this study is called μ=-2 mode Coupled Bunch Instability. To suppress it, we developed new feedback components for longitudinal coupled bunch instability. We have same mechanism feedback components for KEKB, but it supports only μ=-1 mode instability. Since a large current makes μ=-1 mode instability big, there is a possibility that suppression is difficult only by using KEKB components. In order to deal with this problem, new components we developed support μ=-1, -2, and -3 mode instabilities, and we improved the performance and usability as compared to existing components. We schedule studies using a beam at Phase-II.

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THPAB116

Evaluation of Digital LLRF Control System Performance at STF in KEK

3992

SUSPSIK087

use link to see paper's listing under its alternate paper code

S.B. Wibowo, N. Liu
Sokendai, Ibaraki, Japan
T. Matsumoto, S. Michizono, T. Miura, F. Qiu
KEK, Ibaraki, Japan

The Superconducting RF Test Facility (STF) at the High Energy Accelerator Research Organization (KEK) was built for research and development of the International Linear Collider (ILC). Several digital low-level radio frequency (LLRF) control systems were developed at the STF. The purposes of these developments are to construct a minimal configuration of the ILC LLRF system and achieve the amplitude and phase stability of the accelerating field in the superconducting accelerator. Evaluations of digital LLRF control systems were conducted during the conditioning of eight superconducting cavities performed between October and November 2016. The digital LLRF control system configured for ILC was demonstrated and the performance fulfilled the required stability criteria of the accelerating field in the ILC. These evaluations are reported in this paper.

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THPAB117

Development of a New LLRF System Based on MicroTCA.4 for the SPring-8 Storage Ring

3996

T. Ohshima, H. Ego, N. Hosoda, H. Maesaka
RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
T. Fukui
RIKEN SPring-8 Center, Innovative Light Sources Division, Hyogo, Japan
M. Ishii
JASRI/SPring-8, Hyogo-ken, Japan

SPring-8 is a 3rd generation synchrotron radiation facility, which has been operated since 1997. The analog-circuit-based rf modules now in use at the storage ring are obsolete and hard to be maintained. The renewal of them with modern digital ones is underway and the developed LLRF system will be used for the operation of SPring-8-II. We built an amplitude and phase stabilizing system with commercial MicroTCA.4 modules. A motor driver controlled through EtherCAT was newly adapted to the cavity tuner. The system was implemented to the high power rf test stand which consists of a 1 MW klystron, a circulator, and a 508.58 MHz cavity. The rf power was successfully regulated to keep the cavity voltage with an amplitude deviation of less than 0.1% and a phase stability of less than 0.1 degree in rms. We are also developing new MTCA.4 modules: a digitizer AMC having sampling rate of 370 MHz and 16bit resolution, and a signal conditioning RTM. These modules are used for under-sampling rf detection achieving simple composition and more robustness to the ambient parameter changes. We will start installation of the digital system to one of four rf stations in the storage ring in summer 2017.

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THPAB123

Low Level RF Control System Architecture OF IR-FEL

4014

B. Du, G. Huang, L. Lin, W. Liu, Z.R. Zhou
USTC/NSRL, Hefei, Anhui, People's Republic of China

Infrared free electron laser (IR-FEL) is one type of laser driven by accelerator and generated by undulator. It is built by National Synchrotron Radiation Laboratory (NSRL). Compared to synchrotron radiation light source, it have much higher demand of beam quality. Low level RF control system (LLRF) need to reach higher controlled accuracy corresponded to the demand. Accelerating structure which contains one pre-buncher, one buncher and two accelerating tube can accelerate beam to 60MeV. Frequency distribution system use direct digital synthesizer technology to generate 5 signal of different frequency. LLRF system detect 8 channels signal, one for control loop, and the others for monitor and interlock. The hardware contain MTCA.4 architecture which is advanced in global; RF board for downconverter and IQ modulation output; DSP board for sampling, controller and transmission.

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THPAB124

DSP Frame and Algorithm of LLRF of IR-FEL

4017

B. Du, G. Huang, L. Lin, W. Liu, Z.R. Zhou
USTC/NSRL, Hefei, Anhui, People's Republic of China

Infrared Free Electron Laser (IR-FEL) use linear accelerator to accelerate electron to relative speed and then generate simulated radiation of infrared wavelength by periodic magnetic field of undulator. The amplitude and phase of microwave field need to be controlled precisely by low level RF control system (LLRF) to meet the high quality demand of electron from undulator. This paper mainly introduce the digital signal processing frame and feedback algorithm. Four times frequency sampling can realize IQ demodulation precisely and reduce DC offset, amplitude sampling error is less than 0.075% and phase sampling error is less than 0.1°. Pipeline CORDIC can calculate amplitude and phase by parallel processing and shift operation. Phase calculating accuracy reach 0.0005° when iteration count is 18. FIR filter is used to improve frequency selected performance. Feedback loop use digital PI controller to adjust system output.

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THPAB129

Contribution to the ESS LLRF System by Polish Electronic Group

4026

J. Szewiński, M. Gosk, Z. Gołębiewski, P. Krawczyk, I.M. Kudla
NCBJ, Świerk/Otwock, Poland
A. Abramowicz, K. Czuba, M.G. Grzegrzolka, I. Rutkowski
Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland
W. Cichalewski, D.R. Makowski, A. Napieralski
TUL-DMCS, Łódź, Poland

Funding: Described work will be done as a part of polish in-kind contribution, granted by the Polish Ministry of Science and Higher Education in the decision number DIR/WK/2016/03.
Development of the LLRF system at ESS is coordinated by the Lund University, but part of it, LLRF systems for M-Beta and H-Beta sections, will be delivered within in-kind contribution from Poland. This document will describe the scope of work, work plan, and technical details of the selected components of the M-Beta and H-Beta LLRF systems sections. Described contribution will be made by the Polish Electronic Group (PEG), a consortium of three scientific units. LLRF system for ESS will be made of both, commercially available components and components designed specially for this project, and those last ones will be presented and described here. Except the technical details, the organizational aspects, such as schedule, project management or quality control, will be presented as well.

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THPAB131

Test of the Feedback and Feedforward Control Loop for Digital LLRF System of 1 MeV/n RFQ

4028

H.S. Jeong, Y.-S. Cho, H.S. Kim, J.H. Kim, S.G. Kim, H.-J. Kwon, Y.G. Song
Korea Atomic Energy Research Institute (KAERI), Gyeongbuk, Republic of Korea

Funding: This work has been supported through KOMAC (Korea of Multi-purpose Accelerator Complex) operation fund of KAERI by MSIP (Ministry of Science, ICT and Future Planning)
KOMAC (Korea Multi-purpose Accelerator Complex) has a plan to develop the multipurpose ion irradiation system. This system includes the ion source, LEBT, RFQ and MEBT systems to transport ion particles to the target. In particular, the RFQ (Radio Frequency Quadrupole) system should receive 200 MHz RF within 1 % amplitude error stability. To supply stable 200 MHz RF signal to the RFQ cavity, the LLRF (Low-Level Radio Frequency) system should be controlled through a control system which implemented using commercial digital board. This 1 MeV/n RFQ LLRF system has a concept to minimize the number of the analog components for minimizing the control error. For this, the FPGA (Field Programmable Gate Array) in the digital board will control the frequency of the output sinusoidal signal. In addition, this LLRF system applied the direct sampling, Non-IQ sampling, direct RF generation and fast IQ set update rate algorithm. In this presentation, the LLRF PI control and feed-forward control logic test using 200 MHz dummy cavity will be described.
LLRF, direct sampling, Non-IQ, RFQ, control loop, feedback, feedforward

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THPAB134

Latest Development of the ALBA DLLRF

4034

A. Salom, B. Bravo, M. Broseta, E. Morales, J.R. Ocampo, F. Pérez, P. Solans
ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain

The Digital LLRF of ALBA has been implemented using commercial cPCI boards with Virtex-4 FPGA, fast ADCs and fast DACs. The firmware of the FPGA is based on IQ demodulation technique and the main feed-back loops adjust the phase and amplitude of the cavity voltage and also the resonance frequency of the cavity. This paper summarizes the latest LLRF developments done to improve performance of the RF systems and beam stability, including feed-forward loops based on phase modulation to compensate disturbances due to RF trip, beam loading compensation and Power Unbalance Compensation Loop for RF amplifiers Combination.

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THPAB135

Digital LLRF for MAX IV

4037

A. Salom, F. Pérez
ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
Å. Andersson, R. Lindvall, L. Malmgren, A.M. Milan, A.M. Mitrovic
MAX IV Laboratory, Lund University, Lund, Sweden

The MAX IV facility consists of a 3 GeV Storage Ring(SR), a 1.5 GeV SR, and a linear accelerator (fed by two guns) that serves as a full-energy injector to the rings, but also as a driver for the Short Pulse Facility. The RF systems of the two SRs work at 100MHz. There are 6 normal conducting capacity loaded accelerating cavities and three Landau passive cavities in the 3GeV SR. In the 1.5GeV SR there are two accelerating cavities and two Landau cavities with the same characteristics. Each of these cavities is fed by a modular 60kW SSA. In the 3 GeV SR the power will be doubled by adding a second SSA when required. A digital Low Level RF system has been developed using commercial uTCA boards, with a Virtex-6 FPGA mother board (Perseus 601X) and two double stack FMC boards with fast ADCs and DACs. The large capabilities of state-of-the-art FPGAs allowed including the control of two normal conducing cavities and two landau cavities in one single LLRF system, reducing the development costs. Other utilities like the handling of fast interlocks and post-mortem analysis were also added to this system. This paper summarizes the main capabilities and performance of this DLLRF.

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THPAB141

Control and Operation of a Wideband RF System in CERN's PS Booster

4050

M.E. Angoletta, S.C.P. Albright, A. Findlay, M. Haase, M. Jaussi, J.C. Molendijk, M.M. Paoluzzi, J. Sanchez-Quesada
CERN, Geneva, Switzerland

A prototype wideband High-Level RF (HLRF) sys-tem based on Finemet metal alloy has been installed in CERN's PS Booster (PSB) Ring 4 in 2012, within the frame of the LHC Injectors Upgrade (LIU) project. A digital Low-Level RF (LLRF) system was used to control the HLRF system to ascertain the capabilities of the combined system, especially under heavy beam loading. The testing campaign was satisfactory and in 2015 the CERN management decided to replace all ferrite-based systems with Finemet ones for the PS Booster restart in 2020. This paper describes the LLRF features implemented for operating the wideband HLRF system and the main beam results obtained. Hints on the LLRF evolution in view of the PSB HLRF renovation are also given.

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THPAB142

Initial Beam Results of CERN ELENA's Digital Low-Level RF System

4054

M.E. Angoletta, S.C.P. Albright, S. Energico, S. Hancock, M. Jaussi, A.J. Jones, J.C. Molendijk, M.M. Paoluzzi, J. Sanchez-Quesada
CERN, Geneva, Switzerland

The Extra Low ENergy Antiproton (ELENA) decelerator is under commissioning at CERN. This decelerator is equipped with a new digital low-level RF (LLRF) system, in-house developed and belonging to the LLRF family already deployed in CERN's PS Booster and Low Energy Ion Ring (LEIR) synchrotrons. New features to adapt it to the demanding requirements of ELENA's operation include new, low noise ADC daughtercards and a fixed-frequency clocking scheme. This paper gives an overview of the LLRF system; initial beam results are also shown together with hints on the future system upgrade.

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THPAB143

Operational Experience With the New Digital Low-Level RF System for CERN's PS Booster

4058

M.E. Angoletta, S.C.P. Albright, A. Findlay, S. Hancock, M. Jaussi, J.C. Molendijk, J. Sanchez-Quesada
CERN, Geneva, Switzerland

The four rings of CERN's PS Booster have been equipped in 2014 with a new digital low-level RF (LLRF) system based upon a new, in-house developed LLRF family. This is a second-generation LLRF family that has been since then deployed on other synchrotrons. The paper provides an overview of the system's commissioning and first years of operation. In particular, an overview is given of the main system features and capabilities, such as beam loops and longitudinal beam blowup implementation. Operational improvements with respect to the previous, analogue digital LLRF are also mentioned, together with the planned system evolution to satisfy new requirements.

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THPAB144

The New LEIR Digital Low-Level RF System

4062

M.E. Angoletta, S.C.P. Albright, A. Findlay, M. Haase, S. Hancock, M. Jaussi, J.C. Molendijk, M.M. Paoluzzi, J. Sanchez-Quesada
CERN, Geneva, Switzerland

CERN's Low Energy Ion Ring (LEIR) low-level RF (LLRF) system has been successfully upgraded in 2016 to the new digital, LLRF family for frequency-sweeping synchrotrons developed at CERN. For LEIR it implements not only beam loops but also the voltage and phase loops required for the control of two Finemet-based High-Level RF (HLRF) systems. This paper gives an overview of the system and of new requirements implemented, such as the parallel operation of two HLRF systems. Beam results for the 2016 lead ions run are also shown.

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THPAB148

DIGITAL LOW LEVEL RF CONTROL SYSTEM FOR THE TAIWAN PHOTON SOURCE

4077

F.Y. Chang, L.-H. Chang, M.H. Chang, L.J. Chen, F.-T. Chung, M.-C. Lin, Z.K. Liu, C.H. Lo, C.L. Tsai, Ch. Wang, M.-S. Yeh, T.-C. Yu
NSRRC, Hsinchu, Taiwan

The Taiwan Photon Source (TPS) is a 3 GeV, 500 mA, 499.65 MHz, 3rd generation synchrotron light source at NSRRC. To achieve the requirements of system flexibil-ity, fault diagnosis, precise control and high noise reduc-tion, a digital low level RF (DLLRF) control system based on Field Programmable Gate Array (FPGA) was developed. The communication interface is based on Raspberry Pi. The feedback loop performance of the control system was tested on the booster of the Taiwan Photon Source (TPS) with 950 kV gap voltage.

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THPAB150

Input Output Controller of Digital Low Level RF System in NSRRC

4083

Z.K. Liu, F.Y. Chang, L.-H. Chang, M.H. Chang, L.J. Chen, F.-T. Chung, M.-C. Lin, C.H. Lo, C.L. Tsai, Ch. Wang, M.-S. Yeh, T.-C. Yu
NSRRC, Hsinchu, Taiwan

Low Level Radio Frequency (LLRF) systems operating at NSRRC are based on analog technology and are used both at the Taiwan Light Source and the Taiwan Photon Source. In order to have better RF field stability, a new digital LLRF system based on Field Programmable Gate Array (FPGA) was developed. A card-sized single-board computer is used as the input/output controller of the digital LLRF system and its design and implementation with EPICS applications are reported here.

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THPAB152

Digital Low Level RF Systems for Diamond Light Source

4089

P. Gu, C. Christou, P. Hamadyk, D. Spink, I.S. Uzun
DLS, Oxfordshire, United Kingdom
E. Morales, F. Pérez, A. Salom
ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain

Analogue low level RF (LLRF) systems have been used to date for both Diamond storage ring and booster RF cavities. They have been in operation for nearly ten years without a major problem. However, digital LLRF can offer new desirable functionalities such as fast data logging, 'probe blip' blockage and automation of routine tasks. Better performance is also envisaged with up to date hardware. A digital LLRF system has been developed with Alba Synchrotron as a common platform for the storage ring and booster, including superconducting and normal conducting RF cavities. The new digital LLRF is based on Virtex6 FPGA and fast ADCs and DACs. One system has been built and verified in the Diamond booster with beam. The design will be implemented for all other Diamond RF cavities.

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THPVA152

Performance of ATCA LLRF System at LCLS

4817

J.M. D'Ewart, J.C. Frisch, B. Hong, K.H. Kim, J.J. Olsen, D. Van Winkle
SLAC, Menlo Park, California, USA

Funding: Work supported by Department of Energy contract DE-AC02-76SF00515.
The low level RF control for the SLAC LINAC is being upgraded to provide improved performance and maintainability. The new LLRF system is based on the SLAC ATCA common platform hardware. RF control is achieved through a high performance FPGA based DDS/DDC system. The signal processing is designed to be phase insensitive, allowing the use of modest performance on-board digitizer clock and LO. The prototype LLRF control system was installed and used to operate RF station 28-2 in LCLS-I. Design details and prototype performance results will be presented.

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THPVA154

LLRF Hardware Testbench

4821

J.A. Diaz Cruz, S. Biedron, S.V. Milton
CSU, Fort Collins, Colorado, USA
A.L. Benwell, A. Ratti
SLAC, Menlo Park, California, USA

With continual advances and the development of new technologies, such as superconducting cavities, particle accelerators have become more complex. New accelerator designs have more demanding stability requirements for the cavity RF fields, up to 0.01% in amplitude and 0.01' in phase for hundreds of cavities in Continuous Wave (CW) operation. Compensating for disturbances from mechanical resonances, microphonics, natural couplings and unwanted channel crosstalk is a challenge for the Low Level Radio Frequency (LLRF) control systems. For the upgrade to the Linac Coherent Light Source (LCLS-II) at SLAC, a high performance LLRF control system is being designed and developed to drive the Solid State Amplifiers (SSA) and control the cavity fields within specifications. The different components of the LLRF hardware have been designed, constructed and tested separately. Here, we describe a test environment, still under development, for integration, characterization and qualification of the LLRF system with all the LLRF hardware integrated in a single prototype rack.

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