IPAC2019 - List of Keywords (LLRF)

Paper	Title	Other Keywords	Page
MOPTS106	Barrier Bucket Studies in the CERN PS	cavity, proton, ISOL, kicker	1128
	M. Vadai, A. Alomainy QMUL, London, United Kingdom H. Damerau CERN, Geneva, Switzerland
	Part of the residual beam loss during the Multi-Turn Extraction (MTE) of fixed target beams from the CERN Proton Synchrotron (PS) can be attributed to kicker magnets switching while the beam is coasting with the main RF systems off before extraction. Generating a barrier bucket to deplete the longitudinal line density of the coasting beam during the kicker rise time can reduce these losses. Beam tests have been performed with an existing Finemet cavity in the PS, which is normally operated as a wideband feedback kicker. To drive the cavity, a beam synchronous waveform synthesizer based on programmable logic has been developed. It produces a pre-distorted signal which ideally results in a single period sinusoidal voltage pulse with programmable parameters at the gap of the cavity, once or multiple times per revolution. The modelling of the behavior of the power amplifier and the cavity is essential to achieve an anti-symmetric voltage pulse with little pre- and post-pulse ripple. The design of the beam-synchronous waveform generator is presented together with results from initial beam studies with the created barrier buckets in the PS.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS106
About •	paper received ※ 18 April 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
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TUPRB059	Solid State Amplifier of SC Linac for Shine	cavity, linac, hardware, factory	1814
	Y.B. Zhao, Q. Chang, K. Xu, Zh.G. Zhang, S.J. Zhao, X. Zheng SINAP, Shanghai, People’s Republic of China
	Shanghai HIgh repetition rate XFEL aNd Extreme light facility （SHINE）is a platform for technique and science research which energy is 8GeV, operated in CW-mode and beam current is 0.2mA. It include a LINAC of 8GeV, three undulator lines, three beam lines and ten experiment stations. SHINE is located underground 30 meters. The lengths of facility is 3kM and the length of LINAC is 1.2km. The acceleration architecture of LINAC consists of six hundred 1.3GHz and sixteen 3.9GHz TELSA type cavities. The 5.2kW SSA will drive the 1.3GHz superconductive cavities and 2kW SSA will power the 3.9GHz superconductive cavities. Four 1.3GHz prototypes of SSA have already been produced, the design and performance are showed in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB059
About •	paper received ※ 14 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019
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WEPRB004	Sawtooth Generation and Regulation with a Single FPGA for TRIUMF’s ARIEL Prebuncher	controls, FPGA, cavity, pick-up	2801
	X.L. Fu, T. Au, K. Fong, Q. Zheng TRIUMF, Vancouver, Canada
	TRIUMF’s ARIEL prebuncher is powered by a sawtooth waveform which is the combination of an 11.79MHz, a 23.57MHz and a 35.36MHz components. The generation, control and regulation of these three components are all incorporated digitally inside a single FPGA. This FPGA can be standalone or inserted inside a VXI module. Commands and controls of these components can be directly through Ethernet, or indirectly through register-base or message-base VXI addresses.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB004
About •	paper received ※ 10 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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WEPRB007	RF Commissioning of the SPIRAL2 RFQ in CW Mode and Beyond Nominal Field	cavity, rfq, controls, vacuum	2804
	M. Di Giacomo, R. Ferdinand, H. Franberg, J.-M. Lagniel, G. Normand GANIL, Caen, France M. Desmons, P. Galdemard, Y. Lussignol, O. Piquet, S. Sube CEA-DRF-IRFU, France
	The SPIRAL2 RFQ was recently successfully commissioned at nominal voltage of 114 kV, corresponding to 1.65 Kilpatrick factor. The paper describes limitations of the RFQ main subsystems, cavity conditioning difficulties, as well as changes implemented in the LLRF and automatic procedures to simplify turn on and operation of the whole system.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB007
About •	paper received ※ 26 April 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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WEPRB016	Simulation of Quench Detection Algorithms for Helmholtz Zentrum Berlin SRF Cavities	cavity, SRF, FPGA, controls	2834
	P. Echevarria, A. Neumann, A. Ushakov HZB, Berlin, Germany B. Garcia UPV-EHU, Leioa, Spain J. Jugo University of the Basque Country, Faculty of Science and Technology, Bilbao, Spain
	The Helmholtz Zentrum Berlin is carrying out two accelerator projects which make use of high gradient SRF cavities: BERLinPro* and BESSY-VSR. In both projects, a prompt detection of a quench is crucial to avoid damages in the cryomodules and cavities themselves. In this paper, the response of real time estimation of the cavity parameters* using the transmitted and forward RF signals is simulated, in order to perform the quench detection. The time response of the estimated half bandwidth is compared with the dissipated power in the cavity walls for the different type of SRF cavities used in both projects, i.e., BERLinPro’s photoinjector, booster and linac, and BESSY-VSR 1.5 GHz and 1.75 GHz cavities. As an intermediate step prior to the implementation in an mTCA.4 system together with the LLRF control and test with a real cavity, the algorithm has been implemented using a National Instruments FPGA board to check the its proper behavior.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB016
About •	paper received ※ 16 April 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019
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WEPRB021	Commissioning of S-band Cavity Test Facility at Elettra for Conditioning of High Gradient Structures for the Fermi Linac Upgrade	cavity, FEL, hardware, linac	2846
	N. Shafqat, L. Giannessi, C. Masciovecchio, M. Milloch, C. Serpico, M. Svandrlik, M. Trovò Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy M. Bopp, R. Zennaro PSI, Villigen PSI, Switzerland T.G. Lucas The University of Melbourne, Melbourne, Victoria, Australia
	FERMI is the seeded Free Electron Laser (FEL) user facility at Elettra laboratory in Trieste, operating in the VUV to soft X-rays spectral range. In order to extend the FEL spectral range to shorter wavelengths, a feasibility study for increasing the Linac energy from 1.5 GeV to 1.8 GeV is actually going on. A short prototype of a new High Gradient (HG) S-band accelerating structure has been built in collaboration with Paul Scherrer Institute (PSI). The new structures are intended to replace the present Backward Travelling Wave (BTW) sections and tailored to be operated at a gradient of 30 MV/m. For RF conditioning and high power testing of prototype, a Cavity Test Facility (CTF) is commissioned at FERMI. The test facility is equipped with RF pulse compressor system and a dedicated diagnostic for breakdown rate (BDR) measurements and events localization. In this paper we present in detail cavity test facility of FERMI and high power testing of the first prototype.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB021
About •	paper received ※ 08 April 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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WEPRB022	RF System Upgrade for Elettra 2.0	cavity, storage-ring, HOM, klystron	2849
	C. Pasotti, M. Bocciai, M. Rinaldi Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
	The Elettra 2.0 low emittance light source project has triggered the review of the installed RF system’s performances and the analyses of the new machine requirement. This study includes the imperative revamp of the RF power sources. The trade off between the best theoretical RF system design and the available room for installation and budget for Elettra 2.0 has been translated into the operational plan reported here. The first planned step is the installation of 100 kW 500 MHz solid state based transmitters.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB022
About •	paper received ※ 13 May 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019
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WEPRB063	Connection of 12 GHz High Power RF from the XBOX 1 High Gradient Test Stand to the CLEAR Electron LINAC	klystron, linac, software, electron	2960
	A.V. Edwards Cockcroft Institute, Lancaster University, Lancaster, United Kingdom N. Catalán Lasheras, S. Gonzalez Anton, G. McMonagle, S. Pitman, B.J. Woolley, V. del Pozo Romano CERN, Meyrin, Switzerland
	A new RF system is being established at XBOX1 to drive two §I{100}{MV/m} CLIC structures in the CLEAR electron linac. In the past, these structures had been powered by RF from PET structures excited by a drive beam. This drive beam is no longer available. The upgrade will reroute power from the §I{50}{MW} klystron and pulse compressor which was previously used to power the structure in XBOX1. During the upgrade, the LLRF system will be optimised to improve the modulation of the output signals and down-mixing of the returning signals to obtain accurate phase and amplitude information. The design of the improved LLRF and software, along with phase noise measurements and comparisons with the old system are made in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB063
About •	paper received ※ 14 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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WEPRB078	RF Commissioning and Performance in the CBETA ERL	cavity, operation, controls, linac	3003
	N. Banerjee, K.E. Deitrick, J. Dobbins, G.H. Hoffstaetter, R.P.K. Kaplan, M. Liepe, C.W. Miller, P. Quigley, E.N. Smith, V. Veshcherevich Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Funding: This work was supported by the New York State Energy Research and Development Authority, Contract No. DE-SC0012704 with the U.S. Department of Energy and NSF award DMR-0807731. The Cornell-BNL ERL Test Accelerator (CBETA) is a new multi-turn energy recovery linac currently being commissioned at Cornell University. It uses a superconducting main linac to accelerate electrons by 36 MeV and recover their energy. The energy recovery process is sensitive to fluctuations in the accelerating field of all cavities. In this paper, we outline our semi-automated RF commissioning procedure, which starts from automatic coarse tuning of the cavity all the way to adjusting the field control loops. We show some results of using these tools and describe the recent performance of the RF system during our ongoing commissioning phase.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB078
About •	paper received ※ 14 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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WEPTS049	Flat-Bottom Instabilities in the CERN SPS	simulation, impedance, HOM, feedback	3224
	M. Schwarz, K. Iliakis, A. Lasheen, G. Papotti, J. Repond, E.N. Shaposhnikova, H. Timko CERN, Meyrin, Switzerland
	At beam intensities of 2.6·10¹¹ protons per bunch, required at SPS injection for the High Luminosity LHC beam, longitudinal instabilities can degrade the beam quality delivered by the SPS, the LHC injector at CERN. In this paper, we concentrate on beam instability at flat bottom. The dependence of the instability threshold on longitudinal emittance and LLRF system settings was measured, to help identify the impedance driving this instability. While reducing the longitudinal emittance reduces the losses at injection, it can drive the beam unstable. The LLRF system of the SPS (partially) compensates beam loading, but also affects the instability. The effect of the different LLRF systems (feedback, feedforward, phase loop and longitudinal damper) and fourth harmonic RF system on the instability was investigated. The measurements are compared with simulations performed with the longitudinal tracking code BLonD.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS049
About •	paper received ※ 10 May 2019 paper accepted ※ 19 May 2019 issue date ※ 21 June 2019
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THYPLS1	RF Controls Towards Femtosecond and Attosecond Precision	cavity, controls, detector, FEL	3414
	F. Ludwig, J. Branlard, L. Butkowski, M.K. Czwalinna, M. Hierholzer, M. Hoffmann, M. Killenberg, T. Lamb, J. Marjanovic, U. Mavrič, J.M. Müller, S. Pfeiffer, H. Schlarb, Ch. Schmidt, L. Springer DESY, Hamburg, Germany M. Kuntzsch, K. Zenker HZDR, Dresden, Germany
	In the past two decades, RF controls have improved by two orders in magnitude achieving meanwhile sub-10 fs phase stabilities and 10^-4 amplitude precision. Advances are through improved field detection methods and massive usage of digital signal procession on very powerful field programmable gate arrays (FPGAs). The question rise, what can be achieved in the next 10 years? In this talk, a review is given of existing systems and strategies, current stability limitations of RF control system and new technologies with the potential to achieve attosecond resolutions.
	Slides THYPLS1 [10.328 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THYPLS1
About •	paper received ※ 15 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
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THPMP007	MICROTCA TECHNOLOGY LAB AT DESY: CURRENT CASES IN TECHNOLOGY TRANSFER	controls, operation, hardware, electron	3459
	T. Walter, I. Mahns, H. Schlarb DESY, Hamburg, Germany
	Funding: The MicroTCA Technology Lab (A Helmholtz Innovation Lab) is supported by the Helmholtz Association under grant HIL-002. MicroTCA-based LLRF systems for beam control and beam diagnostics are gaining traction in many facilities around the world. Over the past decade, a comprehensive portfolio of hardware solutions (boards, crates, backplanes) has become available to cater for demanding signal processing applications in state-of-the-art facilities like the European XFEL. Gradually, industrial applications of MicroTCA also have become more common. In response various requests, DESY has opened the MicroTCA Technology Lab (A Helmholtz Innovation Lab) in April 2018 as a service unit for research and industry with a focus on: - Customer-specific developments in MicroTCA (hardware, firmware, software), - High-end test and measurement services, - Consulting and system integration. We report on intermediate results and emerging projects after one year of operation, with transfer examples from the industrial automation and medical technology sectors as well as overlapping developments for the physics research community.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPMP007
About •	paper received ※ 14 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
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THPRB024	Piezo Controls For The European XFEL	cavity, controls, FEL, linac	3856
	K.P. Przygoda, J. Branlard, L. Butkowski, M.K. Grecki, M. Hierholzer, M. Omet, H. Schlarb DESY, Hamburg, Germany
	The European X-Ray Free Electron Laser (E-XFEL) accelerator is a pulse machine. The typical time duration of a radio frequency (RF) pulse is about 1.3 ms. The RF power transmitted to the superconducting RF (SCRF) cavity as a set of successive pulses (10 Hz repetition rate), causes strong mechanical stresses inside the cavity. The mechanical deformations of the RF cavity are typically caused by the Lorentz force detuning (LFD). The cavity can be tuned to a 1.3 GHz resonance frequency during the RF pulse using fast piezo tuners. Since the E-XFEL will use around 800 cavities (each cavity with double piezos), a distributed architecture with multi-channel digital and analog control circuits seems to be essential. The most sought-after issue is high-voltage, high-current piezo driving circuit dedicated to multi-channel configuration. The driving electronics should allow a maximum piezo protection against any kind of failure. The careful automation of the piezo tuners control and its demonstration for the high gradient conditions a real challenge. The first demonstration of piezo controls applied for chosen RF stations of the E-XFEL linear accelerator (linac) are presented and obtained results are briefly discussed within this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB024
About •	paper received ※ 30 April 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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THPRB044	LLRF Control System for RF GUN at SXFEL Test Facility	gun, controls, FEL, FPGA	3912
	L. Li, Q. Gu, Y.J. Liu, C.C. Xiao, J.Q. Zhang SINAP, Shanghai, People’s Republic of China Y.F. Liu, Z. Wang SARI-CAS, Pudong, Shanghai, People’s Republic of China
	A Soft X-ray Free Electron Laser Test Facility (SXFEL-TF) based on normal conducting linear accelerator was constructed at the Shanghai Synchrotron Radiation Facility (SSRF) campus by a joint team of Shanghai Institute of Applied Physics and Tsinghua University. It consists of multiple Radio Frequency (RF) stations with standing wave cavity (RF Gun) and traveling wave accelerating structures working at different frequencies. Low Level Radio Frequency (LLRF) system is used to measure the RF field in the cavities or structures and correct the fluctuation in RF fields with pulse-to-pulse feedback controllers. This paper describes the hardware and architecture of the LLRF system for electromagnetic filed stabilization inside the radio frequency electron gun, in the SXFEL-TF. A complete control path has be presented, including RF front-end board, I/Q detector and feedback controller. Algorithms used to stabilize the RF field have been presented as well as the software environment used to provide remote access to the control device. Finally, the performance of the LLRF system that was realized in the beam commissioning is presented and meets the high accuracy requirements.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB044
About •	paper received ※ 23 April 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019
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THPRB045	A Novel Microwave Switch-Based LLRF System for Long-Term System Phase Drift Calibration	controls, coupling, ISOL, experiment	3915
	Z.Y. Lin, Y.-C. Du, W.-H. Huang, C.-X. Tang, J. Tang TUB, Beijing, People’s Republic of China G. Huang, Y.L. Xu LBNL, Berkeley, California, USA Z. Sun, D. Zhang HZCY Technologies Co., Ltd., Beijing, People’s Republic of China
	The long-term phase drift is one of the important issue for the stability of the Low level RF system. The signal crosstalk and temperature effect on the RF field detectors will significantly limited the performance of the phase detecting precise and the phase locking. A novel micro-wave switch-based LLRF system has been developed in Tsinghua accelerator lab. The microwave switch are ap-plied to in the chopper circuit to turn continuous signal into pulse signal in the time domain to avoid the mutual signal interference. In this paper the LLRF system based on microwave switch is present. The preliminary long-term experiments result shows the phase stability can achieve about 50fs RMS slow drift; and the peak-to-peak value of the slow drift was (~2°C p-p) over 4 days.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB045
About •	paper received ※ 22 April 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019
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THPRB046	The Preliminary Long-Term Slow Drift Calibration Study in Low-Level Rf System	experiment, monitoring, timing, controls	3918
	Z.Y. Lin, Y.-C. Du, W.-H. Huang, C.-X. Tang, J. Tang TUB, Beijing, People’s Republic of China G. Huang, Y.L. Xu LBNL, Berkeley, California, USA Z. Sun, D. Zhang HZCY Technologies Co., Ltd., Beijing, People’s Republic of China
	The phase drift of the RF signal in the low-level radio frequency (LLRF) system is observed in the long-term operation, which limits the performance and stability of the LLRF system. The long-term drift was reproduced in the lab. Its effect and sources of error were explored in the simple LLRF46 board and the simplest LLRF system. It is founded that the temperature will significantly lead to the phase distortion of the two signal channels, although with the same electron device. The distortion will finally cause the long-term drift with temperature floating. A fixed phase calibration signal (CAL signal) is applied to deal with the signal channels difference. The preliminary tests were conducted and the results were analysed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB046
About •	paper received ※ 22 April 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019
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THPRB050	LLRF System Modelling and Controller Design in UED	electron, cavity, controls, cathode	3924
	Y.Q. Li, K. Fan, Y. Song HUST, Wuhan, People’s Republic of China
	In the Ultrafast Electron Diffraction (UED) facility for investigating material structure, drifts of amplitude and phase in cavity have different effects on beam quality. So it is critical for pump-probe experiments in the UED to keep accurate synchronization between the laser and electron. To achieve the desired 50fs resolution, the Low Level Radio Frequency (LLRF) controller in S-band normal conducting cavity needs to satisfy the stability: ±0.01% (rms) for the amplitude and ±0.01° (rms) for the phase, respectively. Then we can study the performance of the RF control system by simulating the LLRF system. In the simulation program, feedback, feed-forward algorithms, and beam current variations can be simulated in a Matlab/Simulink environment. This paper shows that a model-based controller design can meet the necessary requirements of the field regulation and implement the algorithms.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB050
About •	paper received ※ 20 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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THPRB068	Upgrade of CERN’s PSB Digital Low-Level RF System	HLRF, controls, operation, proton	3958
	M.E. Angoletta, S.C.P. Albright, A. Findlay, M. Jaussi, J.C. Molendijk, N. Pittet CERN, Geneva, Switzerland
	The CERN PS Booster (PSB) is the first circular accelerator in the LHC proton injector chain. The upgrade of this four-ring machine is underway within the framework of the LHC Injectors Upgrade project. The existing digital Low-Level RF (LLRF) system will also be upgraded. This paper outlines the LLRF capabilities required, their implementation and the challenges involved. Results of tests carried out to prepare for the LLRF upgrade are given.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB068
About •	paper received ※ 13 May 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019
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THPRB069	The New Digital Low-Level RF System for CERN’s Extra Low Energy Antiproton Machine	proton, extraction, antiproton, operation	3962
	M.E. Angoletta, M. Jaussi, J.C. Molendijk CERN, Geneva, Switzerland
	CERN’s new Extra Low ENergy Antiproton accelerator/decelerator (ELENA) completed its initial commissioning in 2018. This machine is equipped with a new digital Low-Level RF (LLRF) system that implements beam and cavity loops as well as longitudinal diagnostics. ELENA’s LLRF was instrumental for machine commissioning by decelerating some 1 E7 antiprotons from 5.3 MeV to 100 keV. Commissioning with H⁻ ions took also place. Challenges faced included coping with low beam intensity and the wide frequency swing. This paper gives an overview of the LLRF system capabilities and operation. Beam results achieved with both H⁻ ions and antiprotons are also shown.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB069
About •	paper received ※ 13 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019
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THPRB070	A New Digital Low-Level RF and Longitudinal Diagnostic System for CERN’s AD	proton, diagnostics, antiproton, operation	3966
	M.E. Angoletta, S.C.P. Albright, A. Findlay, M. Jaussi, J.C. Molendijk, V.R. Myklebust CERN, Geneva, Switzerland
	The Antiproton Decelerator (AD) has been routinely providing 3 E7 antiprotons since July 2000 at 100 MeV/c from 3.5 GeV/c. It will be refurbished during the Long Shutdown 2 (LS2) to provide reliable operation for the new Extra Low ENergy Antiproton (ELENA) ring. AD will be equipped with a new digital Low-Level RF (LLRF) system before its restart in 2021. Diagnostics to measure beam intensity, Δp/p and Schottky spectra will also be developed. This paper is an overview of the planned capabilities and implementations, as well as of the challenges to overcome.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB070
About •	paper received ※ 13 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
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THPRB082	The CERN SPS Low Level RF upgrade Project	cavity, controls, feedback, acceleration	4005
	G. Hagmann, P. Baudrenghien, J.D. Betz, J. Egli, G. Kotzian, M. Rizzi, L. Schmid, A. Spierer, T. Włostowski CERN, Meyrin, Switzerland F.J. Galindo Guarch Universitat Politécnica de Catalunya, Barcelona, Spain
	The High Luminosity LHC project (HL-LHC) calls for the doubling of the beam intensity injected from the Super Proton Synchrotron (SPS). This is not possible with the present RF system consisting of four 200 MHz cavities. An upgrade was therefore launched, consisting of the installation of two more cavities during the machine shutdown in 2019-2020 (LS2). Installation of more cavities requires the installation of extra Low Level RF (LLRF) electronics. The present LLRF system consists of the original equipment installed in the 1970s, plus some additions dating from the late 1990s when the SPS was commissioned as LHC injector. The High-Power RF up-grade has motivated a complete renovation of the LLRF during LS2; use of a MicroTCA platform, use of a digital deterministic link for synchronization (the so-called White Rabbit), use of an absolute clock for the processing, new algorithms for reducing the cavity impedance, and a complete re-design of the beam control loops and slip-stacking.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB082
About •	paper received ※ 13 May 2019 paper accepted ※ 19 May 2019 issue date ※ 21 June 2019
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THPRB094	Study of the System Stability for the Digital Low Level RF System Operated at High Beam Currents	cavity, controls, feedback, simulation	4042
	Z.K. Liu, F.Y. Chang, L.-H. Chang, M.H. Chang, S.W. Chang, L.J. Chen, F.-T. Chung, Y.T. Li, M.-C. Lin, C.H. Lo, Ch. Wang, M.-S. Yeh, T.-C. Yu NSRRC, Hsinchu, Taiwan
	The purpose of a Low-Level Radio Frequency (LLRF) system is to control the amplitude and phase of the field in the accelerating cavity. A digital LLRF (DLLRF) system will be installed in the Taiwan Photon Source (TPS) storage ring in 2019. The system stability depends much on the feedback parameters. An instability of the cavity voltage controlled by a DLLRF was observed during machine tests with high beam current and low feedback gain. A simulation model for the digital LLRF system with beam-cavity interaction was developed to investigate this instability and simulations and machine test results will be presented here.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB094
About •	paper received ※ 07 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
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THPRB107	A Novel Design of a Laser Phase Monitor for AWA RF Photocathode Electron Gun	laser, electron, feedback, controls	4076
	W. Liu, M.E. Conde, D.S. Doran, G. Ha, J.G. Power, J.H. Shao, C. Whiteford, E.E. Wisniewski ANL, Argonne, Illinois, USA
	It is critical to maintain a stable laser phase for RF photocathode electron gun to achieve high beam stability. In order to achieve a higher beam stability for AWA(Argonne Wakefield Accelerator) beamline, a novel laser phase monitor has been designed to allow us to monitor and feedback on. Both the design and its applications at AWA are presented in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB107
About •	paper received ※ 13 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
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THPRB115	MicroTCA Based LLRF Control Systems for TARLA and NICA	cavity, controls, operation, electron	4089
	P. Nonn, C. Gümüş, C.K. Kampmeyer, H. Schlarb, Ch. Schmidt, T. Walter DESY, Hamburg, Germany
	The MicroTCA Technology Lab (A Helmholtz Innovation Lab) is preparing two turn-key Low Level RF control systems for facilities outside of DESY. The Turkish Accelerator and Radiation Laboratory in Ankara (TARLA) is a 40 MeV electron accelerator with continuous wave (CW) RF operation. The MicroTCA based LLRF control system is responsible for two normal conducting and four superconducting cavities, controlling the RF as well as cavity tuning via motors and piezos. The Light Ion Linac (LILAC) is one of the injectors for the Nuclotron-based Ion Collider Facility (NICA) in Dubna, Russia. It will provide a 7 MeV/u pulsed, polarized proton or deuteron beam. The MicroTCA based LLRF control system will control five normal conducting cavities, consisting of one RFQ, one buncher, one debuncher and two IH-cavities. MicroTCA Technology Lab is cooperating with BEVATECH GmbH, Frankfurt, Germany, who designed the cavities. This paper gives a brief overview of the design of both LLRF systems as well as the status of their assembly.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB115
About •	paper received ※ 15 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
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THPTS022	The Realization of Iterative Learning Control for J-PARC LINAC LLRF Control System	controls, linac, experiment, DTL	4155
	S. Li J-PARC, KEK & JAEA, Ibaraki-ken, Japan Z. Fang, Y. Fukui, K. Futatsukawa, F. Qiu KEK, Ibaraki, Japan Y. Sato, S. Shinozaki JAEA/J-PARC, Tokai-mura, Japan
	The beam current of j-parc linac was planned to increase to 60 mA. The stronger beam current will lead to higher beam loading effect. Due to the low Q factor of cavity in high β section of linac, the traditional PID feedback & feedforward control method may have to face huge challenges. In order to make the system run better at 60 mA, the iterative learning control (ILC) method was put forward to use in LLRF control system. All the ILC operations are done in EPICS-PC. By installing the PyEpics module, we can use python programs to realize the data interaction between EPICS system and PC and further realize the ILC algorithm. In this paper, the architecture of ILC methods will be introduced. The performance of ILC method will be reported.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS022
About •	paper received ※ 15 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
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THPTS060	Sirius Digital LLRF	cavity, controls, FPGA, booster	4244
	A. Salom, F. Pérez ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain R.H.A. Farias, F.K.G. Hoshino, A.P.B. Lima LNLS, Campinas, Brazil
	Sirius is a Synchrotron Light Source Facility based on a 4th generation low emittance storage ring. The facility is presently under construction in Campinas, Brazil, and comprises a 3 GeV electron storage ring, a full energy booster synchrotron and a 120 MeV linac. The booster RF system is based on a single 5-cell cavity driven by a 50 kW amplifier at 500MHz and is designed to operate at 2 Hz rate. The storage ring RF system will start with 1 normal conducting 7-cell cavity. In the final configuration, the system will comprise 2 superconducting cavities, each one driven by a 240 kW RF amplifier. A digital LLRF system based on ALBA LLRF has been designed and commissioned to control 3 different types of cavities: 2 normal conducting single cell cavities, one multi-cell cavity driven by 2 amplifiers and one superconducting cavity driven by 4 amplifiers. The first LLRF System was installed and commissioned in the Sirius Booster in 2019. The performance of the control loops with beam, together with other utilities of the system like automatic start-up, conditioning, fast interlocks and post-mortem analysis will be presented in this paper, as well as possible upgrades for the future
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS060
About •	paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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THPTS075	Performance Tests of a Digital Low-Level Rf-System at the TPS	beam-loading, cavity, storage-ring, controls	4292
	F.Y. Chang, L.-H. Chang, M.H. Chang, S.W. Chang, L.J. Chen, F.-T. Chung, Y.T. Li, M.-C. Lin, Z.K. Liu, C.H. Lo, Ch. Wang, M.-S. Yeh, T.-C. Yu NSRRC, Hsinchu, Taiwan
	A digital low-level RF (DLLRF) control system for the cavity gap voltage is now common throughout the world. At the Taiwan Photon Source (TPS) we installed and operated a DLLRF in the booster ring in 2018 successfully and plan to install it also in the storage ring in 2019. Operational and beam loading tests of the DLLRF at the storage ring are ongoing. The performance of the DLLRF in the presence of a large number of 60 Hz harmonics and its stability for gap voltage and phase will be discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS075
About •	paper received ※ 10 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
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Paper

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Other Keywords

Page

MOPTS106

Barrier Bucket Studies in the CERN PS

cavity, proton, ISOL, kicker

1128

M. Vadai, A. Alomainy
QMUL, London, United Kingdom
H. Damerau
CERN, Geneva, Switzerland

Part of the residual beam loss during the Multi-Turn Extraction (MTE) of fixed target beams from the CERN Proton Synchrotron (PS) can be attributed to kicker magnets switching while the beam is coasting with the main RF systems off before extraction. Generating a barrier bucket to deplete the longitudinal line density of the coasting beam during the kicker rise time can reduce these losses. Beam tests have been performed with an existing Finemet cavity in the PS, which is normally operated as a wideband feedback kicker. To drive the cavity, a beam synchronous waveform synthesizer based on programmable logic has been developed. It produces a pre-distorted signal which ideally results in a single period sinusoidal voltage pulse with programmable parameters at the gap of the cavity, once or multiple times per revolution. The modelling of the behavior of the power amplifier and the cavity is essential to achieve an anti-symmetric voltage pulse with little pre- and post-pulse ripple. The design of the beam-synchronous waveform generator is presented together with results from initial beam studies with the created barrier buckets in the PS.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS106

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paper received ※ 18 April 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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TUPRB059

Solid State Amplifier of SC Linac for Shine

cavity, linac, hardware, factory

1814

Y.B. Zhao, Q. Chang, K. Xu, Zh.G. Zhang, S.J. Zhao, X. Zheng
SINAP, Shanghai, People’s Republic of China

Shanghai HIgh repetition rate XFEL aNd Extreme light facility （SHINE）is a platform for technique and science research which energy is 8GeV, operated in CW-mode and beam current is 0.2mA. It include a LINAC of 8GeV, three undulator lines, three beam lines and ten experiment stations. SHINE is located underground 30 meters. The lengths of facility is 3kM and the length of LINAC is 1.2km. The acceleration architecture of LINAC consists of six hundred 1.3GHz and sixteen 3.9GHz TELSA type cavities. The 5.2kW SSA will drive the 1.3GHz superconductive cavities and 2kW SSA will power the 3.9GHz superconductive cavities. Four 1.3GHz prototypes of SSA have already been produced, the design and performance are showed in this paper.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB059

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paper received ※ 14 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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WEPRB004

Sawtooth Generation and Regulation with a Single FPGA for TRIUMF’s ARIEL Prebuncher

controls, FPGA, cavity, pick-up

2801

X.L. Fu, T. Au, K. Fong, Q. Zheng
TRIUMF, Vancouver, Canada

TRIUMF’s ARIEL prebuncher is powered by a sawtooth waveform which is the combination of an 11.79MHz, a 23.57MHz and a 35.36MHz components. The generation, control and regulation of these three components are all incorporated digitally inside a single FPGA. This FPGA can be standalone or inserted inside a VXI module. Commands and controls of these components can be directly through Ethernet, or indirectly through register-base or message-base VXI addresses.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB004

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paper received ※ 10 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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WEPRB007

RF Commissioning of the SPIRAL2 RFQ in CW Mode and Beyond Nominal Field

cavity, rfq, controls, vacuum

2804

M. Di Giacomo, R. Ferdinand, H. Franberg, J.-M. Lagniel, G. Normand
GANIL, Caen, France
M. Desmons, P. Galdemard, Y. Lussignol, O. Piquet, S. Sube
CEA-DRF-IRFU, France

The SPIRAL2 RFQ was recently successfully commissioned at nominal voltage of 114 kV, corresponding to 1.65 Kilpatrick factor. The paper describes limitations of the RFQ main subsystems, cavity conditioning difficulties, as well as changes implemented in the LLRF and automatic procedures to simplify turn on and operation of the whole system.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB007

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paper received ※ 26 April 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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WEPRB016

Simulation of Quench Detection Algorithms for Helmholtz Zentrum Berlin SRF Cavities

cavity, SRF, FPGA, controls

2834

P. Echevarria, A. Neumann, A. Ushakov
HZB, Berlin, Germany
B. Garcia
UPV-EHU, Leioa, Spain
J. Jugo
University of the Basque Country, Faculty of Science and Technology, Bilbao, Spain

The Helmholtz Zentrum Berlin is carrying out two accelerator projects which make use of high gradient SRF cavities: BERLinPro* and BESSY-VSR**. In both projects, a prompt detection of a quench is crucial to avoid damages in the cryomodules and cavities themselves. In this paper, the response of real time estimation of the cavity parameters*** using the transmitted and forward RF signals is simulated, in order to perform the quench detection. The time response of the estimated half bandwidth is compared with the dissipated power in the cavity walls for the different type of SRF cavities used in both projects, i.e., BERLinPro’s photoinjector, booster and linac, and BESSY-VSR 1.5 GHz and 1.75 GHz cavities. As an intermediate step prior to the implementation in an mTCA.4 system together with the LLRF control and test with a real cavity, the algorithm has been implemented using a National Instruments FPGA board to check the its proper behavior.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB016

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paper received ※ 16 April 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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WEPRB021

Commissioning of S-band Cavity Test Facility at Elettra for Conditioning of High Gradient Structures for the Fermi Linac Upgrade

cavity, FEL, hardware, linac

2846

N. Shafqat, L. Giannessi, C. Masciovecchio, M. Milloch, C. Serpico, M. Svandrlik, M. Trovò
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
M. Bopp, R. Zennaro
PSI, Villigen PSI, Switzerland
T.G. Lucas
The University of Melbourne, Melbourne, Victoria, Australia

FERMI is the seeded Free Electron Laser (FEL) user facility at Elettra laboratory in Trieste, operating in the VUV to soft X-rays spectral range. In order to extend the FEL spectral range to shorter wavelengths, a feasibility study for increasing the Linac energy from 1.5 GeV to 1.8 GeV is actually going on. A short prototype of a new High Gradient (HG) S-band accelerating structure has been built in collaboration with Paul Scherrer Institute (PSI). The new structures are intended to replace the present Backward Travelling Wave (BTW) sections and tailored to be operated at a gradient of 30 MV/m. For RF conditioning and high power testing of prototype, a Cavity Test Facility (CTF) is commissioned at FERMI. The test facility is equipped with RF pulse compressor system and a dedicated diagnostic for breakdown rate (BDR) measurements and events localization. In this paper we present in detail cavity test facility of FERMI and high power testing of the first prototype.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB021

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paper received ※ 08 April 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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WEPRB022

RF System Upgrade for Elettra 2.0

cavity, storage-ring, HOM, klystron

2849

C. Pasotti, M. Bocciai, M. Rinaldi
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy

The Elettra 2.0 low emittance light source project has triggered the review of the installed RF system’s performances and the analyses of the new machine requirement. This study includes the imperative revamp of the RF power sources. The trade off between the best theoretical RF system design and the available room for installation and budget for Elettra 2.0 has been translated into the operational plan reported here. The first planned step is the installation of 100 kW 500 MHz solid state based transmitters.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB022

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paper received ※ 13 May 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019

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WEPRB063

Connection of 12 GHz High Power RF from the XBOX 1 High Gradient Test Stand to the CLEAR Electron LINAC

klystron, linac, software, electron

2960

A.V. Edwards
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
N. Catalán Lasheras, S. Gonzalez Anton, G. McMonagle, S. Pitman, B.J. Woolley, V. del Pozo Romano
CERN, Meyrin, Switzerland

A new RF system is being established at XBOX1 to drive two §I{100}{MV/m} CLIC structures in the CLEAR electron linac. In the past, these structures had been powered by RF from PET structures excited by a drive beam. This drive beam is no longer available. The upgrade will reroute power from the §I{50}{MW} klystron and pulse compressor which was previously used to power the structure in XBOX1. During the upgrade, the LLRF system will be optimised to improve the modulation of the output signals and down-mixing of the returning signals to obtain accurate phase and amplitude information. The design of the improved LLRF and software, along with phase noise measurements and comparisons with the old system are made in this paper.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB063

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paper received ※ 14 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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WEPRB078

RF Commissioning and Performance in the CBETA ERL

cavity, operation, controls, linac

3003

N. Banerjee, K.E. Deitrick, J. Dobbins, G.H. Hoffstaetter, R.P.K. Kaplan, M. Liepe, C.W. Miller, P. Quigley, E.N. Smith, V. Veshcherevich
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: This work was supported by the New York State Energy Research and Development Authority, Contract No. DE-SC0012704 with the U.S. Department of Energy and NSF award DMR-0807731.
The Cornell-BNL ERL Test Accelerator (CBETA) is a new multi-turn energy recovery linac currently being commissioned at Cornell University. It uses a superconducting main linac to accelerate electrons by 36 MeV and recover their energy. The energy recovery process is sensitive to fluctuations in the accelerating field of all cavities. In this paper, we outline our semi-automated RF commissioning procedure, which starts from automatic coarse tuning of the cavity all the way to adjusting the field control loops. We show some results of using these tools and describe the recent performance of the RF system during our ongoing commissioning phase.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB078

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paper received ※ 14 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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WEPTS049

Flat-Bottom Instabilities in the CERN SPS

simulation, impedance, HOM, feedback

3224

M. Schwarz, K. Iliakis, A. Lasheen, G. Papotti, J. Repond, E.N. Shaposhnikova, H. Timko
CERN, Meyrin, Switzerland

At beam intensities of 2.6·10¹¹ protons per bunch, required at SPS injection for the High Luminosity LHC beam, longitudinal instabilities can degrade the beam quality delivered by the SPS, the LHC injector at CERN. In this paper, we concentrate on beam instability at flat bottom. The dependence of the instability threshold on longitudinal emittance and LLRF system settings was measured, to help identify the impedance driving this instability. While reducing the longitudinal emittance reduces the losses at injection, it can drive the beam unstable. The LLRF system of the SPS (partially) compensates beam loading, but also affects the instability. The effect of the different LLRF systems (feedback, feedforward, phase loop and longitudinal damper) and fourth harmonic RF system on the instability was investigated. The measurements are compared with simulations performed with the longitudinal tracking code BLonD.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS049

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paper received ※ 10 May 2019 paper accepted ※ 19 May 2019 issue date ※ 21 June 2019

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THYPLS1

RF Controls Towards Femtosecond and Attosecond Precision

cavity, controls, detector, FEL

3414

F. Ludwig, J. Branlard, L. Butkowski, M.K. Czwalinna, M. Hierholzer, M. Hoffmann, M. Killenberg, T. Lamb, J. Marjanovic, U. Mavrič, J.M. Müller, S. Pfeiffer, H. Schlarb, Ch. Schmidt, L. Springer
DESY, Hamburg, Germany
M. Kuntzsch, K. Zenker
HZDR, Dresden, Germany

In the past two decades, RF controls have improved by two orders in magnitude achieving meanwhile sub-10 fs phase stabilities and 10^-4 amplitude precision. Advances are through improved field detection methods and massive usage of digital signal procession on very powerful field programmable gate arrays (FPGAs). The question rise, what can be achieved in the next 10 years? In this talk, a review is given of existing systems and strategies, current stability limitations of RF control system and new technologies with the potential to achieve attosecond resolutions.

Slides THYPLS1 [10.328 MB]

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paper received ※ 15 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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THPMP007

MICROTCA TECHNOLOGY LAB AT DESY: CURRENT CASES IN TECHNOLOGY TRANSFER

controls, operation, hardware, electron

3459

T. Walter, I. Mahns, H. Schlarb
DESY, Hamburg, Germany

Funding: The MicroTCA Technology Lab (A Helmholtz Innovation Lab) is supported by the Helmholtz Association under grant HIL-002.
MicroTCA-based LLRF systems for beam control and beam diagnostics are gaining traction in many facilities around the world. Over the past decade, a comprehensive portfolio of hardware solutions (boards, crates, backplanes) has become available to cater for demanding signal processing applications in state-of-the-art facilities like the European XFEL. Gradually, industrial applications of MicroTCA also have become more common. In response various requests, DESY has opened the MicroTCA Technology Lab (A Helmholtz Innovation Lab) in April 2018 as a service unit for research and industry with a focus on: - Customer-specific developments in MicroTCA (hardware, firmware, software), - High-end test and measurement services, - Consulting and system integration. We report on intermediate results and emerging projects after one year of operation, with transfer examples from the industrial automation and medical technology sectors as well as overlapping developments for the physics research community.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPMP007

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paper received ※ 14 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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THPRB024

Piezo Controls For The European XFEL

cavity, controls, FEL, linac

3856

K.P. Przygoda, J. Branlard, L. Butkowski, M.K. Grecki, M. Hierholzer, M. Omet, H. Schlarb
DESY, Hamburg, Germany

The European X-Ray Free Electron Laser (E-XFEL) accelerator is a pulse machine. The typical time duration of a radio frequency (RF) pulse is about 1.3 ms. The RF power transmitted to the superconducting RF (SCRF) cavity as a set of successive pulses (10 Hz repetition rate), causes strong mechanical stresses inside the cavity. The mechanical deformations of the RF cavity are typically caused by the Lorentz force detuning (LFD). The cavity can be tuned to a 1.3 GHz resonance frequency during the RF pulse using fast piezo tuners. Since the E-XFEL will use around 800 cavities (each cavity with double piezos), a distributed architecture with multi-channel digital and analog control circuits seems to be essential. The most sought-after issue is high-voltage, high-current piezo driving circuit dedicated to multi-channel configuration. The driving electronics should allow a maximum piezo protection against any kind of failure. The careful automation of the piezo tuners control and its demonstration for the high gradient conditions a real challenge. The first demonstration of piezo controls applied for chosen RF stations of the E-XFEL linear accelerator (linac) are presented and obtained results are briefly discussed within this paper.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB024

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paper received ※ 30 April 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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THPRB044

LLRF Control System for RF GUN at SXFEL Test Facility

gun, controls, FEL, FPGA

3912

L. Li, Q. Gu, Y.J. Liu, C.C. Xiao, J.Q. Zhang
SINAP, Shanghai, People’s Republic of China
Y.F. Liu, Z. Wang
SARI-CAS, Pudong, Shanghai, People’s Republic of China

A Soft X-ray Free Electron Laser Test Facility (SXFEL-TF) based on normal conducting linear accelerator was constructed at the Shanghai Synchrotron Radiation Facility (SSRF) campus by a joint team of Shanghai Institute of Applied Physics and Tsinghua University. It consists of multiple Radio Frequency (RF) stations with standing wave cavity (RF Gun) and traveling wave accelerating structures working at different frequencies. Low Level Radio Frequency (LLRF) system is used to measure the RF field in the cavities or structures and correct the fluctuation in RF fields with pulse-to-pulse feedback controllers. This paper describes the hardware and architecture of the LLRF system for electromagnetic filed stabilization inside the radio frequency electron gun, in the SXFEL-TF. A complete control path has be presented, including RF front-end board, I/Q detector and feedback controller. Algorithms used to stabilize the RF field have been presented as well as the software environment used to provide remote access to the control device. Finally, the performance of the LLRF system that was realized in the beam commissioning is presented and meets the high accuracy requirements.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB044

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paper received ※ 23 April 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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THPRB045

A Novel Microwave Switch-Based LLRF System for Long-Term System Phase Drift Calibration

controls, coupling, ISOL, experiment

3915

Z.Y. Lin, Y.-C. Du, W.-H. Huang, C.-X. Tang, J. Tang
TUB, Beijing, People’s Republic of China
G. Huang, Y.L. Xu
LBNL, Berkeley, California, USA
Z. Sun, D. Zhang
HZCY Technologies Co., Ltd., Beijing, People’s Republic of China

The long-term phase drift is one of the important issue for the stability of the Low level RF system. The signal crosstalk and temperature effect on the RF field detectors will significantly limited the performance of the phase detecting precise and the phase locking. A novel micro-wave switch-based LLRF system has been developed in Tsinghua accelerator lab. The microwave switch are ap-plied to in the chopper circuit to turn continuous signal into pulse signal in the time domain to avoid the mutual signal interference. In this paper the LLRF system based on microwave switch is present. The preliminary long-term experiments result shows the phase stability can achieve about 50fs RMS slow drift; and the peak-to-peak value of the slow drift was (~2°C p-p) over 4 days.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB045

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paper received ※ 22 April 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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THPRB046

The Preliminary Long-Term Slow Drift Calibration Study in Low-Level Rf System

experiment, monitoring, timing, controls

3918

Z.Y. Lin, Y.-C. Du, W.-H. Huang, C.-X. Tang, J. Tang
TUB, Beijing, People’s Republic of China
G. Huang, Y.L. Xu
LBNL, Berkeley, California, USA
Z. Sun, D. Zhang
HZCY Technologies Co., Ltd., Beijing, People’s Republic of China

The phase drift of the RF signal in the low-level radio frequency (LLRF) system is observed in the long-term operation, which limits the performance and stability of the LLRF system. The long-term drift was reproduced in the lab. Its effect and sources of error were explored in the simple LLRF46 board and the simplest LLRF system. It is founded that the temperature will significantly lead to the phase distortion of the two signal channels, although with the same electron device. The distortion will finally cause the long-term drift with temperature floating. A fixed phase calibration signal (CAL signal) is applied to deal with the signal channels difference. The preliminary tests were conducted and the results were analysed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB046

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paper received ※ 22 April 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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THPRB050

LLRF System Modelling and Controller Design in UED

electron, cavity, controls, cathode

3924

Y.Q. Li, K. Fan, Y. Song
HUST, Wuhan, People’s Republic of China

In the Ultrafast Electron Diffraction (UED) facility for investigating material structure, drifts of amplitude and phase in cavity have different effects on beam quality. So it is critical for pump-probe experiments in the UED to keep accurate synchronization between the laser and electron. To achieve the desired 50fs resolution, the Low Level Radio Frequency (LLRF) controller in S-band normal conducting cavity needs to satisfy the stability: ±0.01% (rms) for the amplitude and ±0.01° (rms) for the phase, respectively. Then we can study the performance of the RF control system by simulating the LLRF system. In the simulation program, feedback, feed-forward algorithms, and beam current variations can be simulated in a Matlab/Simulink environment. This paper shows that a model-based controller design can meet the necessary requirements of the field regulation and implement the algorithms.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB050

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paper received ※ 20 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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THPRB068

Upgrade of CERN’s PSB Digital Low-Level RF System

HLRF, controls, operation, proton

3958

M.E. Angoletta, S.C.P. Albright, A. Findlay, M. Jaussi, J.C. Molendijk, N. Pittet
CERN, Geneva, Switzerland

The CERN PS Booster (PSB) is the first circular accelerator in the LHC proton injector chain. The upgrade of this four-ring machine is underway within the framework of the LHC Injectors Upgrade project. The existing digital Low-Level RF (LLRF) system will also be upgraded. This paper outlines the LLRF capabilities required, their implementation and the challenges involved. Results of tests carried out to prepare for the LLRF upgrade are given.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB068

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paper received ※ 13 May 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019

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THPRB069

The New Digital Low-Level RF System for CERN’s Extra Low Energy Antiproton Machine

proton, extraction, antiproton, operation

3962

M.E. Angoletta, M. Jaussi, J.C. Molendijk
CERN, Geneva, Switzerland

CERN’s new Extra Low ENergy Antiproton accelerator/decelerator (ELENA) completed its initial commissioning in 2018. This machine is equipped with a new digital Low-Level RF (LLRF) system that implements beam and cavity loops as well as longitudinal diagnostics. ELENA’s LLRF was instrumental for machine commissioning by decelerating some 1 E7 antiprotons from 5.3 MeV to 100 keV. Commissioning with H⁻ ions took also place. Challenges faced included coping with low beam intensity and the wide frequency swing. This paper gives an overview of the LLRF system capabilities and operation. Beam results achieved with both H⁻ ions and antiprotons are also shown.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB069

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paper received ※ 13 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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THPRB070

A New Digital Low-Level RF and Longitudinal Diagnostic System for CERN’s AD

proton, diagnostics, antiproton, operation

3966

M.E. Angoletta, S.C.P. Albright, A. Findlay, M. Jaussi, J.C. Molendijk, V.R. Myklebust
CERN, Geneva, Switzerland

The Antiproton Decelerator (AD) has been routinely providing 3 E7 antiprotons since July 2000 at 100 MeV/c from 3.5 GeV/c. It will be refurbished during the Long Shutdown 2 (LS2) to provide reliable operation for the new Extra Low ENergy Antiproton (ELENA) ring. AD will be equipped with a new digital Low-Level RF (LLRF) system before its restart in 2021. Diagnostics to measure beam intensity, Δp/p and Schottky spectra will also be developed. This paper is an overview of the planned capabilities and implementations, as well as of the challenges to overcome.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB070

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paper received ※ 13 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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THPRB082

The CERN SPS Low Level RF upgrade Project

cavity, controls, feedback, acceleration

4005

G. Hagmann, P. Baudrenghien, J.D. Betz, J. Egli, G. Kotzian, M. Rizzi, L. Schmid, A. Spierer, T. Włostowski
CERN, Meyrin, Switzerland
F.J. Galindo Guarch
Universitat Politécnica de Catalunya, Barcelona, Spain

The High Luminosity LHC project (HL-LHC) calls for the doubling of the beam intensity injected from the Super Proton Synchrotron (SPS). This is not possible with the present RF system consisting of four 200 MHz cavities. An upgrade was therefore launched, consisting of the installation of two more cavities during the machine shutdown in 2019-2020 (LS2). Installation of more cavities requires the installation of extra Low Level RF (LLRF) electronics. The present LLRF system consists of the original equipment installed in the 1970s, plus some additions dating from the late 1990s when the SPS was commissioned as LHC injector. The High-Power RF up-grade has motivated a complete renovation of the LLRF during LS2; use of a MicroTCA platform, use of a digital deterministic link for synchronization (the so-called White Rabbit), use of an absolute clock for the processing, new algorithms for reducing the cavity impedance, and a complete re-design of the beam control loops and slip-stacking.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB082

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paper received ※ 13 May 2019 paper accepted ※ 19 May 2019 issue date ※ 21 June 2019

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THPRB094

Study of the System Stability for the Digital Low Level RF System Operated at High Beam Currents

cavity, controls, feedback, simulation

4042

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

The purpose of a Low-Level Radio Frequency (LLRF) system is to control the amplitude and phase of the field in the accelerating cavity. A digital LLRF (DLLRF) system will be installed in the Taiwan Photon Source (TPS) storage ring in 2019. The system stability depends much on the feedback parameters. An instability of the cavity voltage controlled by a DLLRF was observed during machine tests with high beam current and low feedback gain. A simulation model for the digital LLRF system with beam-cavity interaction was developed to investigate this instability and simulations and machine test results will be presented here.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB094

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paper received ※ 07 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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THPRB107

A Novel Design of a Laser Phase Monitor for AWA RF Photocathode Electron Gun

laser, electron, feedback, controls

4076

W. Liu, M.E. Conde, D.S. Doran, G. Ha, J.G. Power, J.H. Shao, C. Whiteford, E.E. Wisniewski
ANL, Argonne, Illinois, USA

It is critical to maintain a stable laser phase for RF photocathode electron gun to achieve high beam stability. In order to achieve a higher beam stability for AWA(Argonne Wakefield Accelerator) beamline, a novel laser phase monitor has been designed to allow us to monitor and feedback on. Both the design and its applications at AWA are presented in this paper.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB107

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paper received ※ 13 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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THPRB115

MicroTCA Based LLRF Control Systems for TARLA and NICA

cavity, controls, operation, electron

4089

P. Nonn, C. Gümüş, C.K. Kampmeyer, H. Schlarb, Ch. Schmidt, T. Walter
DESY, Hamburg, Germany

The MicroTCA Technology Lab (A Helmholtz Innovation Lab) is preparing two turn-key Low Level RF control systems for facilities outside of DESY. The Turkish Accelerator and Radiation Laboratory in Ankara (TARLA) is a 40 MeV electron accelerator with continuous wave (CW) RF operation. The MicroTCA based LLRF control system is responsible for two normal conducting and four superconducting cavities, controlling the RF as well as cavity tuning via motors and piezos. The Light Ion Linac (LILAC) is one of the injectors for the Nuclotron-based Ion Collider Facility (NICA) in Dubna, Russia. It will provide a 7 MeV/u pulsed, polarized proton or deuteron beam. The MicroTCA based LLRF control system will control five normal conducting cavities, consisting of one RFQ, one buncher, one debuncher and two IH-cavities. MicroTCA Technology Lab is cooperating with BEVATECH GmbH, Frankfurt, Germany, who designed the cavities. This paper gives a brief overview of the design of both LLRF systems as well as the status of their assembly.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB115

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paper received ※ 15 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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THPTS022

The Realization of Iterative Learning Control for J-PARC LINAC LLRF Control System

controls, linac, experiment, DTL

4155

S. Li
J-PARC, KEK & JAEA, Ibaraki-ken, Japan
Z. Fang, Y. Fukui, K. Futatsukawa, F. Qiu
KEK, Ibaraki, Japan
Y. Sato, S. Shinozaki
JAEA/J-PARC, Tokai-mura, Japan

The beam current of j-parc linac was planned to increase to 60 mA. The stronger beam current will lead to higher beam loading effect. Due to the low Q factor of cavity in high β section of linac, the traditional PID feedback & feedforward control method may have to face huge challenges. In order to make the system run better at 60 mA, the iterative learning control (ILC) method was put forward to use in LLRF control system. All the ILC operations are done in EPICS-PC. By installing the PyEpics module, we can use python programs to realize the data interaction between EPICS system and PC and further realize the ILC algorithm. In this paper, the architecture of ILC methods will be introduced. The performance of ILC method will be reported.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS022

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paper received ※ 15 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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THPTS060

Sirius Digital LLRF

cavity, controls, FPGA, booster

4244

A. Salom, F. Pérez
ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
R.H.A. Farias, F.K.G. Hoshino, A.P.B. Lima
LNLS, Campinas, Brazil

Sirius is a Synchrotron Light Source Facility based on a 4th generation low emittance storage ring. The facility is presently under construction in Campinas, Brazil, and comprises a 3 GeV electron storage ring, a full energy booster synchrotron and a 120 MeV linac. The booster RF system is based on a single 5-cell cavity driven by a 50 kW amplifier at 500MHz and is designed to operate at 2 Hz rate. The storage ring RF system will start with 1 normal conducting 7-cell cavity. In the final configuration, the system will comprise 2 superconducting cavities, each one driven by a 240 kW RF amplifier. A digital LLRF system based on ALBA LLRF has been designed and commissioned to control 3 different types of cavities: 2 normal conducting single cell cavities, one multi-cell cavity driven by 2 amplifiers and one superconducting cavity driven by 4 amplifiers. The first LLRF System was installed and commissioned in the Sirius Booster in 2019. The performance of the control loops with beam, together with other utilities of the system like automatic start-up, conditioning, fast interlocks and post-mortem analysis will be presented in this paper, as well as possible upgrades for the future

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS060

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paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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THPTS075

Performance Tests of a Digital Low-Level Rf-System at the TPS

beam-loading, cavity, storage-ring, controls

4292

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

A digital low-level RF (DLLRF) control system for the cavity gap voltage is now common throughout the world. At the Taiwan Photon Source (TPS) we installed and operated a DLLRF in the booster ring in 2018 successfully and plan to install it also in the storage ring in 2019. Operational and beam loading tests of the DLLRF at the storage ring are ongoing. The performance of the DLLRF in the presence of a large number of 60 Hz harmonics and its stability for gap voltage and phase will be discussed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS075

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paper received ※ 10 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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