IPAC2018 - List of Keywords (LLRF)

Paper	Title	Other Keywords	Page
MOPMF022	Luminosity Reduction Caused by the Full-Detuning LLRF Scheme on the HL-LHC Crab Cavities	luminosity, cavity, simulation, proton	129
	E. Yamakawa, R. Apsimon, A.C. Dexter Cockcroft Institute, Lancaster University, Lancaster, United Kingdom P. Baudrenghien, R. Calaga, F.J. Galindo Guarch CERN, Geneva, Switzerland
	The High-Luminosity LHC (HL-LHC) crab cavities (CCs) will be installed on both sides of IP1 (ATLAS) and IP5 (CMS) to compensate for the geometric luminosity reduction due to the crossing angle. To cope with the increased beam current (0.55 A DC for LHC, 1.1 A for HL-LHC), the operation of the LLRF system has been changed: rather than fully compensating the transient beam loading, we allow the phase to vary along the turn (100 ps peak-peak with 1.1 A DC). This has been implemented at LHC since July 2017. The CCs have high loaded Q (5e5) and the available RF power is insufficient to follow the bunch phase modulation. The crabbing voltage is not modulated, causing a phase error w.r.t. the individual bunch centroids, leading to transverse kicks of the centroids and an asymmetric crabbing of the bunch cores. We present an analytical model for the resulting luminosity reduction and validate with particle tracking simulations. Due to the symmetry of the bunch filling patterns for the counter-rotating beams, the peak luminosity is reduced by only 2% for nominal HL-LHC parameters at IPs 1 and 5, which is within tolerable limits.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF022
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MOPML034	Development Status of Superconducting RF Transmission Electron Microscope	cavity, acceleration, gun, SRF	481
	N. Higashi, A. Enomoto, Y. Funahashi, T. Furuya, X.J. Jin, Y. Kamiya, S. Michizono, F. Qiu, M. Yamamoto KEK, Ibaraki, Japan S. Yamashita University of Tokyo, Tokyo, Japan
	Now we are developing a new type of transmission electron microscope (TEM) employing the accelerator technologies. In place of a DC thermal gun generally used in conventional TEMs, we apply a photocathode gun and a special-shaped superconducting cavity, named two-mode cavity. The two-mode cavity has two resonant modes of TM010 (1.3 GHz) and TM020 (2.6 GHz). To superimpose these, we can suppress the increase of the energy spread, which is needed for the high-spatial-resolution TEMs. We have already developed some prototypes of the photocathode gun and two-mode cavity, and now in the middle of the performance tests. In this presentation, we will show the latest status of the development.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML034
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TUPAF068	Functional Integration of the RFQ in the ESS Systems	rfq, cavity, controls, vacuum	890
	J.S. Schmidt, E. Bargalló, T. Fay, G. Hulla, B. Lagoguez, R. Montaño, E. Sargsyan, S. Scolari, H. Spoelstra ESS, Lund, Sweden A.C. Chauveau, M. Desmons, O. Piquet CEA/IRFU, Gif-sur-Yvette, France A.J. Johansson Lund University, Lund, Sweden W. Ledda Vitrociset s.p.a, Roma, Italy
	The 352 MHz Radio Frequency Quadrupole (RFQ) for the European Spallation Source ERIC (ESS) will be delivered during 2018. After delivery, installation and tuning of the cavity, the high power RF conditioning will be performed. At this point all the different systems that are needed to condition and operate the RFQ have to be in place and operational. This paper will give an overview of the system analysis that has been performed for the RFQ. The RFQ requirements for the RF system, including the RF distribution system (RFDS), the Low Level RF (LLRF) and the local RF protection system (RFLPS) will be presented. In addition, the paper covers the system integration of the structure in the ESS control and vacuum systems as well as the outcome of a machine protection analysis.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF068
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WEXGBF3	RF System for FRIB Accelerator	controls, cavity, rfq, linac	1765
	D.G. Morris, J. Brandon, N.K. Bultman, K.D. Davidson, A. Facco, P.E. Gibson, L. Hodges, M.G. Konrad, T.L. Larter, H. Maniar, P. Morrison, P.N. Ostroumov, J.T. Popielarski, G. Pozdeyev, H.T. Ren, T. Russo, K. Schrock, R. Walker, J. Wei, T. Xu, Y. Xu, S. Zhao FRIB, East Lansing, USA A. Facco INFN/LNL, Legnaro (PD), Italy
	The RF system of the FRIB driver accelerator includes solid state amplifiers up to 18 kW operating at frequencies from 80.5 MHz to 322 MHz. Much higher power is required for the normal conducting RFQ, ~100 kW, and it is based on vacuum tubes. This invited talk presents the performance of solid state amplifiers and LLRF in off-line testing and on-line testing of the RFQ amplifier.
	Slides WEXGBF3 [14.107 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEXGBF3
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WEPAF051	LLRF Operation and Performance at the European XFEL	electron, FEL, operation, MMI	1934
	M. Omet, V. Ayvazyan, J. Branlard, L. Butkowski, M. Hierholzer, M. Killenberg, D. Kostin, L. Lilje, S. Pfeiffer, H. Schlarb, Ch. Schmidt, V. Vogel, N. Walker DESY, Hamburg, Germany
	The European X-ray Free-Electron Laser (XFEL) at Deutsches Elektronen-Synchrotron (DESY), Hamburg, Germany is a user facility providing ultrashort hard and soft X-ray flashes with a high brilliance. All LLRF stations of the injector, covering the normal conducting RF gun, A1 (8 1.3 GHz superconducting cavities (SCs)) and AH1 (8 3.9 GHz SCs), were successfully commissioned by the end of 2015. The commissioning of LLRF stations A2 to A23 (32 1.3 GHz SCs each) in the XFEL accelerator tunnel (XTL) was concluded in June 2017. SASE light was produced in SASE undulator section SA1 and delivered to the first users in September 2017, marking the beginning of regular user operation. The current state of the LLRF systems, the experience gained during operation and the performance achieved in terms of stability and energy reach are presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF051
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WEPAK012	Developing Kalman Filter Based Detuning Control with a Digital SRF CW Cavity Simulator	cavity, controls, SRF, FPGA	2114
	A. Ushakov, P. Echevarria, A. Neumann HZB, Berlin, Germany
	Funding: Work supported by German Bundesministerium für Bildung und Forschung, Land Berlin, and grants of the Helmholtz Association Continuous wave operated superconducting cavities experiencing small net beam loading and thus operate potentially at narrow bandwidth require precise detuning control to reach the high stability requirements for RF fields within facilities as FEL or ERL based photon sources. Especially microphonics compensation down to sub-hertz detuning regime besides improving stability reduces the risk of rise of Lorentz force detuning driven ponderomotive instabilities. Usually the complex and second order nature of the mechanical to RF detuning transfer functions of cavity and cavity-tuner system require for more advanced control schemes. In this paper we will show the application of a Kalman filter based detuning estimator algorithm first introduced during IPAC2017 [1] to the SRF cavity simulator developed at Helmholtz Zentrum Berlin [2]. Results using the algorithm in observer mode to detuning compensation attempts in closed loop mode are presented. * A. Ushakov, P. Echevarria, A. Neumann, Proc. of IPAC 2017, Copenhagen, Denmark
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WEPAK013	SRF Cavity Simulator for LLRF Algorithms Debugging	cavity, controls, SRF, FPGA	2118
	P. Echevarria, J. Knobloch, A. Neumann, A. Ushakov HZB, Berlin, Germany E. Aldekoa, J. Jugo University of the Basque Country, Faculty of Science and Technology, Bilbao, Spain
	Funding: Work supported by German Bundesministerium für Bildung und Forschung, Land Berlin, and grants of Helmholtz Association The availability of niobium superconducting cavities, ei-ther due to a lack of a real cavity or due to the time needed for the experiment set up (vacuum, cryogenics, cabling, etc.), is limited, and thus it can block or delay the develop-ment of new algorithms such as low level RF control. Hardware-in-the-loop simulations, where an actual cavity is replaced by an electronics system, can help to solve this issue. In this paper we present a Cavity Simulator imple-mented in a National Instruments PXI equipped with an FPGA module. This module operates with one intermedi-ate frequency input which is IQ-demodulated and fed to the electrical cavity's model, where the transmitted and re-flected voltages are calculated and IQ-modulated to gener-ate two intermediate frequency outputs. Some more ad-vanced features such as mechanical vibration modes driven by Lorentz-force detuning or external microphonics have also been implemented. This Cavity Simulator is planned to be connected to an mTCA chassis to close the loop with a LLRF control system.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAK013
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WEPAK018	LLRF Control Unit for SuperKEKB Injector Linac	controls, linac, klystron, timing	2134
	T. Miura, M. Akemoto, D.A. Arakawa, H. Katagiri, T. Matsumoto, F. Qiu, Y. Yano KEK, Ibaraki, Japan N. Liu Sokendai, Ibaraki, Japan
	The low-level RF (LLRF) control unit based on the digital system has been developed for a stable and high precision pulse modulation for the SuperKEKB. The RF pulse is changed at a 50-Hz repetition rate for the top-up injection to four different rings by the event system. The LLRF control unit has not only the pulse modulator, but also other functions: VSWR meter, RF monitor, event receiver (EVR), and pulse-shortening detection.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAK018
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WEPAL001	LLRF Control and Master Oscillator System for Damping Ring at SuperKEKB	controls, cavity, injection, linac	2137
	T. Kobayashi, K. Akai, A. Kabe, K. Nakanishi, M. Nishiwaki, J.-I. Odagiri KEK, Ibaraki, Japan H. Deguchi, K. Hayashi, J. Mizuno Mitsubishi Electric TOKKI Systems, Amagasaki, Hyogo, Japan K. Hirosawa Sokendai, Ibaraki, Japan
	For SuperKEKB, new low level RF (LLRF) control systems has ben developed and they worked successfully in the first beam commissioning (Phase-1) of SuperKEKB, which was accomplished in 2016. Damping ring (DR) was newly constructed for positron beam injection, in order to make significantly emittance smaller for SuperKEKB. The beam commissioning of DR will be conducted in JFY2017 for the Phase-2 commissioning. Phase-2 is scheduled in the last quater of JFY2017. DR has an RF station, and two cavities (or three cavities in future) are driven by a klystron. New LLRF control system for DR (DR-LLRF) was also developed and installed. RF frequency of DR operation is common with the main storage rings (MR) of SuperKEKB. The good performance of DR-LLRF was demonstrated in test operation, and RF conditioning of the pair of two cavities was successfully completed in June 2017. This paper reports the detail of the performance results of DR-LLRF controls, and also the other some relevant issues in LLRF controls for DR, including the master oscillator system (synchronization with the injection linac), are introduced.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL001
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WEPAL008	Low-level RF System for The Chinese ADS Front-end Demo Linac	controls, cavity, linac, interface	2159
	J.Y. Ma, Z. Gao, G. Huang, L.P. Sun IMP/CAS, Lanzhou, People's Republic of China
	The Chinese ADS Front-end Demo Linac (FDL) is constructed to demonstrate the technology of superconducting linac with high proton beam loading of CW 10mA. The low-level RF (LLRF) control system for the ADS FDL is developed by IMP, and the cooperation with TRIUMF. In the normal conducting (NC) section, the normal RF feedback control loop is used. In order to stable the superconducting (SC) cavity with loaded high RF power, the self excited loop with phase locked mode was used on the SC linac. This paper introduces the LLRF control system for buncher, SC linac, and the structures of hardware and the functions of software of these LLRF systems. The operating status of the LLRF systems is also reported.
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WEPAL010	Review of the ELI-NP-GBS Low Level RF and Synchronization Systems	laser, linac, electron, timing	2162
	L. Piersanti, D. Alesini, M. Bellaveglia, F. Cardelli, M. Diomede, A. Gallo, V. Martinelli INFN/LNF, Frascati (Roma), Italy B.B. Baricevic, R. Cerne, G. Jug I-Tech, Solkan, Slovenia M. Diomede Sapienza University of Rome, Rome, Italy P.N. Dominguez Menlo Systems GmbH, Martinsried, Germany
	ELI-NP is a linac based gamma-source in construction at Magurele (RO) by the European consortium EuroGammaS led by INFN. Photons with tunable energy and with intensity and brilliance well beyond the state of the art, will be produced by Compton back-scattering between a high quality electron beam (up to 740 MeV) and a 515 nm intense laser pulse. Production of very intense photon flux with narrow bandwidth requires multi-bunch operation at 100 Hz repetition rate. A total of 13 klystrons, 3 S-band (2856 MHz) and 10 C-band (5712 MHz) will power a total of 14 Travelling Wave accelerating sections (2 S-band and 12 C-band) plus 3 S-band Standing Wave cavities (a 1.6 cell RF gun and 2 RF deflectors). Each klystron is individually driven by a temperature stabilized LLRF module for a maximum flexibility in terms of accelerating gradient, arbitrary pulse shaping (e.g. to compensate beam loading effects in multi-bunch regime) and compensation of long-term thermal drifts. In this paper, the whole LLRF system architecture and bench test results, the RF reference generation and distribution together with an overview of the synchronization system will be described.
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WEPAL017	Adaptive Feedforward Control Design Based on Simulink for the J-PARC LINAC LLRF System	controls, cavity, linac, simulation	2187
	S. Li J-PARC, KEK & JAEA, Ibaraki-ken, Japan Z. Fang, Y. Fukui, K. Futatsukawa, F. Qiu KEK, Ibaraki, Japan S. Mizobata, Y. Sato, S. Shinozaki JAEA/J-PARC, Tokai-mura, Japan
	In j-parc linac, for dealing with high beam loading effect, an adaptive feedforward control method which based on iterative learning control was put forward. At the same time, in order to verify its effectiveness before it is officially put into use, an llrf system simulation model was built in simulink, matlab. In this paper, the architecture of llrf system simulation model will be introduced. The result of iterative learning control (ILC) is summarized.
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WEPAL031	RF Interlock Implementation Using Digital LLRF System for 100 MeV Proton Linac at KOMAC	pick-up, cavity, controls, proton	2233
	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 Multi-purpose Accelerator Complex) operation fund of KAERI by MSIT (Ministry of Science and ICT) KOMAC (Korea Multi-purpose Accelerator Complex) already has operated 100 MeV proton linear accelerator with high availability since 2013. This accelerator is composed of Ion source, LEBT, RFQ and DTL systems to transport proton particles to the target. Total 9 klystrons with 1.6 MWpeak are used to provide controlled RF power to the accelerator cavities with 350 MHz of operating frequency. These klystrons are driven by LLRF systems that the LLRF systems should control the RF and protect the amplifiers and cavities from the abnormal RF. In this article, the RF interlock using cavity pickup signal introduced. When the cavity pickup amplitude breaks away from the adjustable upper or lower limit window, the digital LLRF system interrupts the LLRF output. These implementations were conducted by upgrading the FPGA (Field Programmable Gate Array) logics of the existing digital LLRF system.
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WEPAL039	LCLS-II Gun/Buncher LLRF System Design	gun, cavity, SRF, controls	2258
	G. Huang, K.S. Campbell, L.R. Doolittle, J.A. Jones, Q. Qiang, C. Serrano LBNL, Berkeley, California, USA S. Babel, A.L. Benwell, M. Boyes, G.W. Brown, D. Cha, J.H. De Long, J.A. Diaz Cruz, B. Hong, A. McCollough, A. Ratti, C.H. Rivetta, D. Rogind, F. Zhou SLAC, Menlo Park, California, USA R. Bachimanchi, C. Hovater, D.J. Seidman JLab, Newport News, Virginia, USA B.E. Chase, E. Cullerton, J. Einstein-Curtis, D.W. Klepec Fermilab, Batavia, Illinois, USA J.A. Diaz Cruz CSU, Fort Collins, Colorado, USA
	Funding: This work was supported by the LCLS-II Project and the U.S. Department of Energy, Contract n. DE-AC02-05CH11231. For a free electron laser, the stability of injector is critical to the final electron beam parameters, e.g., beam energy, beam arrival time, and eventually it determines the photon quality. The LCLS-II project's injector contains a VHF copper cavity as the gun and a two-cell L-band copper cavity as its buncher. The cavity designs are inherited from the APEX design, but requires more field stability than demonstrated in APEX operation. The gun LLRF system design uses a connectorized RF front end and low noise digitizer, together with the same general purpose FPGA carrier board used in the LCLS-II SRF LLRF system. The buncher LLRF system directly adopts the SRF LLRF chassis design, but programs the controller to run the normal conducting cavities. In this paper, we describe the gun/buncher LLRF system design, including the hardware design, the firmware design and bench test.
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WEPAL040	High Precision Synchronization Development for HiRES, the Ultrafast Electron Diffraction Beamline at LBNL	laser, controls, electron, gun	2262
	Y. Yang, K.M. Baptiste, M. Betz, L.R. Doolittle, Q. Du, D. Filippetto, G. Huang, F. Ji LBNL, Berkeley, California, USA
	Precise synchronization between the laser and electron is critical for the pump-probe experiments in the HiRES Ultrafast Electron Diffraction facility. We are upgrading the LLRF and laser control system, which ultimately aims at a synchronization below 50 fs RMS between the pump laser pulse and electron probe at the sample plane. Such target poses tight requirements on the RF field stability both in amplitude and phase, and on the synchronization between the RF field and the laser repetition rate. We are presently developing a new LLRF system that has the potential to decrease the overall noise, reaching the required stability of tens of ppm on RF amplitude and phase. For the laser control side, we are replacing the long coaxial cables with fibers for both control signal transmission and laser signal reception. The control transmission side has been implemented, and the timing jitter has been reduced.
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WEPAL046	A New Digital Feedback and Feedforward Controller for Cavity Field Control of the LANSCE Accelerator	controls, cavity, feedback, FPGA	2277
	S. Kwon, L.J. Castellano, D.J. Knapp, J.T.M. Lyles, M.S. Prokop, A. Scheinker, P.A. Torrez LANL, Los Alamos, New Mexico, USA
	Funding: Work Supported by DOE A new digital low-level RF system was designed and has been deployed on the drift-tube-linac section of the Los Alamos Neutron Science Center(LANSCE) proton accelerator. This new system is part of a modernization of the existing analog cavity-field controls that were originally developed and put into service forty-five years ago. For stabilization of the cavity field amplitude and phase during beam loading, a proportional-integral feedback controller, a static beam feedforward controller, and an iterative learning controller working in parallel have been implemented. In this paper, the controller architecture is described, and the performances of the three controllers when beam is being actively accelerated is presented.
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WEPAL053	Dynamic Signal Analysis Based on FPGA for NSRRC DLLRF	cavity, FPGA, controls, feedback	2295
	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
	As DLLRF control system designs for SRF cavities have greatly matured and the FPGA technology has im-proved as well, it is possible now to think about incorporating dynamic signal analysis (DSA). Implementation of a DSA in the FPGA is desired to study the frequency response of the open/closed loop gain in a SRF system. Open loop gain is useful to observe the stability of a SRF system while closed loop gain can be applied to investi-gate the operational bandwidth of the system feedback and also to configure the performance of a PID controller. The DSA function was confirmed by analyzing the frequency response of a digital filter and the results of the analysis will be compared with MATLAB simulations.
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WEPAL054	Digital Low Level Radio Frequency System for the Booster Ring of the Taiwan Photon Source	controls, cavity, operation, booster	2298
	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 accelerating cavity field amplitude and phase. For the Taiwan Photon Source (TPS) at NSRRC, the currently operating LLRF systems are based on analog technology. To have better RF field stability, precise con-trol and high noise reduction, a digital LLRF control sys-tems based on Field Programmable Gate Arrays (FPGA) was developed. We replaced the analog LLRF system with the digital version for the TPS booster ring at the beginning of 2018, and we will replace those in the storage rings in the future. Test results and operational performance of the TPS booster DLLRF system are reported here.
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WEPMF011	Design and Status of Sirius Light Source RF Systems	cavity, storage-ring, booster, lattice	2391
	R.H.A. Farias, A.P.B. Lima, L. Liu, F.S. Oliveira LNLS, Campinas, Brazil
	Sirius is the new synchrotron light source currently under construction at the site of the Brazilian Synchro-tron Light Laboratory (LNLS) in Campinas, Brazil. The facility comprises a 3 GeV electron storage ring, a full energy booster and a 150 MeV linac. This work provides a brief description of the RF system of the booster and storage ring, presenting their main characteristics and specification goals.
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WEPMF054	Design and Status of the MicroTCA.4 Based LLRF System for TARLA	controls, cavity, hardware, operation	2490
	Gumus, C. Gumus, M. Hierholzer, K.P. Przygoda, H. Schlarb, Ch. Schmidt DESY, Hamburg, Germany A.A. Aksoy, A. Aydin Ankara University, Accelerator Technologies Institute, Golbasi / Ankara, Turkey
	The Turkish Accelerator and Radiation Laboratory in Ankara (TARLA) is constructing a 40 MeV Free Electron Laser with continuous wave (CW) RF operation. In order to control and monitor the four superconducting (SC) TESLA type cavities as well as the two normal conducting (NC) buncher cavities, a MicroTCA.4 based LLRF system is foreseen. This highly modular system is further used to control the mechanical tuning of the SC cavities by control of piezo actuators and mechanical motor tuners. This paper focuses on giving brief overview on hardware and software components of LLRF control of TARLA, as well as updates on the ongoing integration tests at DESY.
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WEPML004	Production Tuner Testing for LCLS-II Cryomodule Production	cavity, cryomodule, interface, SRF	2678
	J.P. Holzbauer, Y.M. Pischalnikov, W. Schappert, J.C. Yun Fermilab, Batavia, Illinois, USA C. Contreras-Martinez FRIB, East Lansing, USA
	Funding: This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics. LCLS-II 1.3 GHz cryomodule production is well underway at Fermilab. Several dozen cavity/tuner systems have been tested, including tuning to 1.3 GHz, cold landing frequency, range/sensitivity of the slow tuner, and range/sensitivity of the fast tuner. All this testing information as well as lessons learned from tuner installation will be presented.
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WEPML007	Active Microphonics Compensation for LCLS-II	cavity, controls, resonance, cryomodule	2687
	J.P. Holzbauer, B.E. Chase, J. Einstein-Curtis, Y.M. Pischalnikov, W. Schappert Fermilab, Batavia, Illinois, USA L.R. Doolittle, C. Serrano LBNL, Berkeley, California, USA
	Funding: This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics. Testing of early LCLS-II cryomodules showed microphonics-induced detuning levels well above specification. As part of a risk-mitigation effort, a collaboration was formed between SLAC, LBNL, and Fermilab to develop and implement active microphonics compensation into the LCLS-II LLRF system. Compensation was first demonstrated using a Fermilab FPGA-based development system compensating on single cavities, then with the LCLS-II LLRF system on single and multiple cavities simultaneously. The primary technique used for this effort is a bank of narrowband filter set using the piezo-to-detuning transfer function. Compensation automation, optimization, and stability studies were done. Details of the techniques used, firmware/software implementation, and results of these studies will be presented.
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THYGBE3	RF Controls for High-Q Cavities for the LCLS-II	controls, cavity, cryomodule, EPICS	2929
	C. Serrano, K.S. Campbell, L.R. Doolittle, G. Huang, A. Ratti LBNL, Berkeley, California, USA R. Bachimanchi, C. Hovater JLab, Newport News, Virginia, USA A.L. Benwell, M. Boyes, G.W. Brown, D. Cha, G. Dalit, J.A. Diaz Cruz, J. Jones, R.S. Kelly, A. McCollough SLAC, Menlo Park, California, USA B.E. Chase, E. Cullerton, J. Einstein-Curtis, J.P. Holzbauer, D.W. Klepec, Y.M. Pischalnikov, W. Schappert Fermilab, Batavia, Illinois, USA L.R. Dalesio, M.A. Davidsaver Osprey DCS LLC, Ocean City, USA
	Funding: This work was supported by the LCLS-II Project and the U.S. Department of Energy, Contract n. DE-AC02-76SF00515. The SLAC National Accelerator Laboratory is building LCLS-II, a new 4 GeV CW superconducting (SCRF) Linac as a major upgrade of the existing LCLS. The LCLS-II Low-Level Radio Frequency (LLRF) collaboration is a multi-lab effort within the Department of Energy (DOE) accelerator complex. The necessity of high longitudinal beam stability of LCLS-II imposes tight amplitude and phase stability requirements on the LLRF system (up to 0.01% in amplitude and 0.01° in phase RMS). This is the first time such requirements are expected of superconducting cavities operating in continuous-wave (CW) mode. Initial measurements on the Cryomodule test stands at partner labs have shown that the early production units are able to meet the extrapolated hardware requirements to achieve such levels of performance. A large effort is currently underway for system integration, Experimental Physics and Industrial Control System (EPICS) controls, transfer of knowledge from the partner labs to SLAC and the production and testing of 76 racks of LLRF equipment.
	Slides THYGBE3 [14.383 MB]
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THPAK106	400 MHz Frequency/phase Detector and Counter	detector, controls, FPGA, TRIUMF	3481
	X.L. Fu, B. Ji, Z.G. Yin, T.J. Zhang CIAE, Beijing, People's Republic of China G. Dennison UBC & TRIUMF, Vancouver, British Columbia, Canada K. Fong, M.P. Laverty, Q. Zheng TRIUMF, Vancouver, Canada
	To enhance the performance and precision of TRIUMF Low Level RF system, a frequency/phase detector and counter based on FPGA is developed. The frequency/phase detector and counter is designed as a daughter board of the low level RF control system, and is connected to the mother board with mixed signal connectors. It sends the frequency error data to the PC though VXI databus, and provides two analog phase errors outputs. In current design, one single unit supports four channel discriminations of RF frequencies/phases. Preliminary tests show that the reported phase detector has a bandwidth of 400MHz. A unique implementation of frequency discrimination was carefully carried out to ensure the resolution can reach as high as 1Hz. The phase-frequency detector has been successfully applied to the Accelerator Cryo Module (ACM) system and the requirement of the low level RF control system is satisfied. After a long-term running test, the stability and reliability of the phase-frequency detector are verified.
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THPAL002	RF System Operation of High Current RFQ in ADS Project	rfq, cavity, operation, coupling	3613
	L.P. Sun, R. Huang, C.X. Li, L. Lu, A. Shi, L.B. Shi, W.B. Wang, X.B. Xu, H.W. Zhao IMP/CAS, Lanzhou, People's Republic of China Y. Hu TUB, Beijing, People's Republic of China
	Funding: Work supported by Natural Science Foundation of China， No.11505253 New RF system has been upgraded several times for high-current operation, especially for extra beam power and detuning angle. The current was increased gradually resulting in more and more frequency detuning, and an effective method is to tune the temperature of cavity to compromise detuning. Of course, the power dissipated in cavity and high intensity beam are approximately 120kW resulting in too many power modules operated in the high risk of failure. The specific analysis and simulation were introduced in detail.
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THPAL004	Research and Development of RF System for SC200 Cyclotron	cavity, cyclotron, simulation, acceleration	3616
	G. Chen, C. Chao, G. Liu, X.Y. Long, Z. Peng, Y. Song, Y.S. Wang, C.S. Wei, M. Xu, Q. Yang, X. Zhang, Y. Zhao ASIPP, Hefei, People's Republic of China L. Calabretta, A.C. Caruso INFN/LNS, Catania, Italy O. Karamyshev, G.A. Karamysheva, N.A. Morozov, E. Samsonov, G. Shirkov JINR, Dubna, Moscow Region, Russia
	A 200MeV compact isochronous superconducting cyclotron, named SC200, for proton therapy is under development by collaboration of ASIPP (Hefei, China) and JINR (Dubna, Russia). The radio frequency (RF) system as one of most significant subsystems in cyclotron consists of acceleration cavity, low level RF, RF source and transmission network. SC200 has two cavities connected in the centre, which are operated at 91.5 MHz with second harmonic. To meet the required acceleration voltage, the cavities have been carefully designed with comprised choices between several aspects, such as Q factor, mechanic stability and so on. The low-level RF (LLRF) system has been implemented by using the FPGA to achieve the significant accelerating voltage with an amplitude stability of <0.2% and a phase stability of < 0.1 degree. The cavity and LLRF system have been tested outside of cyclotron, the results will be presented. For future, the commissioning of whole RF system will be started after the assembly of SC200 at the end of 2019.
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THPAL025	New Drift-Tube Linac RF Systems at LANSCE	DTL, controls, detector, cavity	3680
	J.T.M. Lyles, R.E. Bratton, M.S. Prokop, D. Rees LANL, Los Alamos, New Mexico, USA
	Funding: Work supported by the United States Department of Energy, National Nuclear Security Agency, under contract DE-AC52-06NA25396. LANSCE has restored the proton drift-tube linac (DTL) to high-power capability after the original RF-power tube manufacturer could no longer supply devices that consistently met our high-average power requirement. Thales TH628L Diacrodes® now supply RF power to three of the four DTL tanks. These tetrodes reused the existing infrastructure including water-cooling systems, coaxial transmission lines, high-voltage power supplies and capacitor banks. Each transmitter uses a combined pair of power amplifiers to produce up to 3- MW peak and 360- kW of mean power. A new intermediate power amplifier was simultaneously developed using a TH781 tetrode. Design and prototype testing of the high-power stages was completed in 2012, with commercialization following in 2013. Each installation was accomplished during a 4 to 5 month beam outage each year from 2014-2016. A new digital low-level RF control system was designed, built and placed into operation in 2016. The interaction of the dual power amplifiers, the I/Q LLRF, and the DTL cavities provided many challenges that were overcome. The replacement RF systems have completely met our accelerator requirements.
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THPMF007	Commissioning of the Hybrid Superconducting/Normal Conducting RF System in the Diamond Storage Ring	cavity, storage-ring, operation, HOM	4042
	C. Christou, A.G. Day, P. Gu, P.J. Marten, S.A. Pande, D. Spink, A. Tropp DLS, Oxfordshire, United Kingdom
	Two 500 MHz HOM damped normal conducting cavities have been installed in the Diamond storage ring to ensure continuity of operation of Diamond in the event of a failure of one of the two existing superconducting cavities. Following receipt from the manufacturer, the cavities were incorporated into an assembly including vacuum pumping, cooling and interlocked diagnostics and then tested for vacuum integrity and RF performance. Both cavities were then conditioned up to high power in Diamond's RF test facility before being installed in the storage ring in August and November 2017. Conditioning and operation has been carried out using a new digital LLRF system. Results of acceptance tests and commissioning with power and beam are presented, together with the current status of the hybrid RF system and options for further improvement of the system in the near future.
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THPMK064	RF System for SXFEL: C-band, X-band and S-band	FEL, linac, klystron, operation	4446
	W. Fang, Q. Gu, X.X. Huang, L. Li, Z.B. Li, J.H. Tan, C.C. Xiao, J.Q. Zhang, Z.T. Zhao SINAP, Shanghai, People's Republic of China
	Shanghai Soft X-ray FEL facility is under commissioning now, which linac is compased of one S-band injector, C-band main linac and X-band linearizer. In SXFEL S-band injector could provide 200MeV beam energy based on 4 RF power unit, and then 6 C-band RF units boost beam energy to 840MeV based on 33MV/m at least, which will be ramped to 40MV/m in the ungrading. In the middle of S-band and C-band RF system, a X-band RF unit is used as linearizer to make energy spread of electron beam linear distribution, which is important for bunch compressor and FEL radiation. In this paper, details of RF system design and status of SXFEL is introduced, and some operation results are presented.
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THPML100	A High Voltage Feedforward Subsystem of Low Level RF System for the High Power RF System	high-voltage, low-level-rf, experiment, controls	4898
	Z.Y. Lin, Y. C. Du, H.Q. Feng, W.-H. Huang, CY. Song, C.-X. Tang, Y.L. Xu, J. Yang TUB, Beijing, People's Republic of China G. Huang LBNL, Berkeley, California, USA
	The Low Level Radio Frequency control (LLRF) system measures the RF signals from the accelerator tube, compares it with the phase reference received from the timing distribution system, and provides the drive signal to the high power RF system to provide synchronized RF voltage to the electron beam. Usually, the LLRF system can achieve a ~50 fs RMS phase jitter which is limited by the microwave devices. The phase noise arise from the high voltage variation of the high power system will significantly increase phase noise from low level RF signal to high power RF. A high voltage feed forward subsystem is proposed to deal with the phase noise caused by the high voltage jitter of the modulator. The demo system is depolyed in Thomson scattering X-ray source (TTX).and the primary experiment result anaylse is discussed.
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THPML101	A Novel Double Sideband-Based Phase Averaging Line for Phase Reference Distribution System	experiment, laser, FPGA, pick-up	4901
	Z.Y. Lin, Y.-C. Du, W.-H. Huang, Z. Pan, C.-X. Tang, C.-X. Tang, Y.L. Xu, J. Yang TUB, Beijing, People's Republic of China G. Huang LBNL, Berkeley, California, USA
	Coaxial cable based solution is one of the most important scheme in Phase Reference Distribution System. A novel double sideband-based phase averaging line has been developed in Tsinghua accelerator lab. The sender chassis generates the 2856 MHz signal as the forward signal and receives the 2856 MHz signal and the reflected double sideband signal from the receiver. The forward signal is phase-locked with the reference signal, and the forward signal and the sideband signal are adjusted by the FPGA virtual delay line. The preliminary experiments result shows the phase stability can achieve about 1% by signal distorted by the phase shifter.
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THPML121	Compensation of Transient Beam Loading in Ramping Synchrotrons Using a Fixed Frequency Processing Clock	FPGA, cavity, feedback, synchrotron	4957
	F.J. Galindo Guarch, J.M.M.A. Moreno Arostegui Universitat Politécnica de Catalunya, Barcelona, Spain P. Baudrenghien, F.J. Galindo Guarch CERN, Geneva, Switzerland
	Transient beam loading compensation schemes, such as One-Turn-FeedBack (OTFB), require beam synchronous processing (BSP). Swept clocks derived from the RF, and therefore harmonic to the revolution frequency, are widely used in CERN synchrotrons; this simplifies implementation with energy ramping, where the revolution frequency changes. It is however not optimal for state-of-the-art digital hardware that prefers fixed frequency clocks. An alternative to the swept clocking is the use of a deterministic protocol, for example, White Rabbit (WR): a fixed reference clock can be extracted from its data stream, while enabling digital distribution of the RF frequency among other data. New algorithms must be developed for BSP using this fixed clock and the digital data transmitted on the WR link. This is the strategy adopted for the SPS Low Level RF (LLRF) upgrade. The paper gives an overview of the technical, technological and historical motivations for such a paradigm evolution. It lists the problems of fixed clock BSP, and presents an innovative solution based on a real-time variable ratio re-sampler for implementing an OTFB with the new fixed clock scheme.
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THPML123	The ESR Barrier-Bucket LLRF System - Design and First Results	cavity, controls, experiment, synchrotron	4964
	J. Harzheim, D. Domont-Yankulova, K. Groß, H. Klingbeil TEMF, TU Darmstadt, Darmstadt, Germany M. Frey, H. Klingbeil, D.E.M. Lens GSI, Darmstadt, Germany
	At GSI, Darmstadt, Germany, a Barrier-Bucket (BB) RF System is currently under development for the Experimental Storage Ring (ESR). The system consists of two broadband RF cavities, each driven by a solid state amplifier, with the purpose to produce two voltage pulses per beam revolution. This will enable highly sophisticated longitudinal beam manipulations like longitudinal capture, compression and decompression or stacking of the beam. For the LLRF System, several requirements have to be fulfilled. Besides high standards concerning the pulsed gap signal quality (e.g. ringing <2.5%), the system has to provide the flexibility for adiabatic voltage ramp-up and adiabatic pulse shifting with high timing accuracy. A connection to the FAIR Central Control System (CCS) is necessary, as amplitude and phase ramp data will be provided by the CCS. In this contribution, the structure of the ESR BB LLRF system is presented together with experimental results from the first version of the system, which will be installed in the ESR in March 2018.
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Paper

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MOPMF022

Luminosity Reduction Caused by the Full-Detuning LLRF Scheme on the HL-LHC Crab Cavities

luminosity, cavity, simulation, proton

129

E. Yamakawa, R. Apsimon, A.C. Dexter
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
P. Baudrenghien, R. Calaga, F.J. Galindo Guarch
CERN, Geneva, Switzerland

The High-Luminosity LHC (HL-LHC) crab cavities (CCs) will be installed on both sides of IP1 (ATLAS) and IP5 (CMS) to compensate for the geometric luminosity reduction due to the crossing angle. To cope with the increased beam current (0.55 A DC for LHC, 1.1 A for HL-LHC), the operation of the LLRF system has been changed: rather than fully compensating the transient beam loading, we allow the phase to vary along the turn (100 ps peak-peak with 1.1 A DC). This has been implemented at LHC since July 2017. The CCs have high loaded Q (5e5) and the available RF power is insufficient to follow the bunch phase modulation. The crabbing voltage is not modulated, causing a phase error w.r.t. the individual bunch centroids, leading to transverse kicks of the centroids and an asymmetric crabbing of the bunch cores. We present an analytical model for the resulting luminosity reduction and validate with particle tracking simulations. Due to the symmetry of the bunch filling patterns for the counter-rotating beams, the peak luminosity is reduced by only 2% for nominal HL-LHC parameters at IPs 1 and 5, which is within tolerable limits.

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MOPML034

Development Status of Superconducting RF Transmission Electron Microscope

cavity, acceleration, gun, SRF

481

N. Higashi, A. Enomoto, Y. Funahashi, T. Furuya, X.J. Jin, Y. Kamiya, S. Michizono, F. Qiu, M. Yamamoto
KEK, Ibaraki, Japan
S. Yamashita
University of Tokyo, Tokyo, Japan

Now we are developing a new type of transmission electron microscope (TEM) employing the accelerator technologies. In place of a DC thermal gun generally used in conventional TEMs, we apply a photocathode gun and a special-shaped superconducting cavity, named two-mode cavity. The two-mode cavity has two resonant modes of TM010 (1.3 GHz) and TM020 (2.6 GHz). To superimpose these, we can suppress the increase of the energy spread, which is needed for the high-spatial-resolution TEMs. We have already developed some prototypes of the photocathode gun and two-mode cavity, and now in the middle of the performance tests. In this presentation, we will show the latest status of the development.

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TUPAF068

Functional Integration of the RFQ in the ESS Systems

rfq, cavity, controls, vacuum

890

J.S. Schmidt, E. Bargalló, T. Fay, G. Hulla, B. Lagoguez, R. Montaño, E. Sargsyan, S. Scolari, H. Spoelstra
ESS, Lund, Sweden
A.C. Chauveau, M. Desmons, O. Piquet
CEA/IRFU, Gif-sur-Yvette, France
A.J. Johansson
Lund University, Lund, Sweden
W. Ledda
Vitrociset s.p.a, Roma, Italy

The 352 MHz Radio Frequency Quadrupole (RFQ) for the European Spallation Source ERIC (ESS) will be delivered during 2018. After delivery, installation and tuning of the cavity, the high power RF conditioning will be performed. At this point all the different systems that are needed to condition and operate the RFQ have to be in place and operational. This paper will give an overview of the system analysis that has been performed for the RFQ. The RFQ requirements for the RF system, including the RF distribution system (RFDS), the Low Level RF (LLRF) and the local RF protection system (RFLPS) will be presented. In addition, the paper covers the system integration of the structure in the ESS control and vacuum systems as well as the outcome of a machine protection analysis.

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WEXGBF3

RF System for FRIB Accelerator

controls, cavity, rfq, linac

1765

D.G. Morris, J. Brandon, N.K. Bultman, K.D. Davidson, A. Facco, P.E. Gibson, L. Hodges, M.G. Konrad, T.L. Larter, H. Maniar, P. Morrison, P.N. Ostroumov, J.T. Popielarski, G. Pozdeyev, H.T. Ren, T. Russo, K. Schrock, R. Walker, J. Wei, T. Xu, Y. Xu, S. Zhao
FRIB, East Lansing, USA
A. Facco
INFN/LNL, Legnaro (PD), Italy

The RF system of the FRIB driver accelerator includes solid state amplifiers up to 18 kW operating at frequencies from 80.5 MHz to 322 MHz. Much higher power is required for the normal conducting RFQ, ~100 kW, and it is based on vacuum tubes. This invited talk presents the performance of solid state amplifiers and LLRF in off-line testing and on-line testing of the RFQ amplifier.

Slides WEXGBF3 [14.107 MB]

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WEPAF051

LLRF Operation and Performance at the European XFEL

electron, FEL, operation, MMI

1934

M. Omet, V. Ayvazyan, J. Branlard, L. Butkowski, M. Hierholzer, M. Killenberg, D. Kostin, L. Lilje, S. Pfeiffer, H. Schlarb, Ch. Schmidt, V. Vogel, N. Walker
DESY, Hamburg, Germany

The European X-ray Free-Electron Laser (XFEL) at Deutsches Elektronen-Synchrotron (DESY), Hamburg, Germany is a user facility providing ultrashort hard and soft X-ray flashes with a high brilliance. All LLRF stations of the injector, covering the normal conducting RF gun, A1 (8 1.3 GHz superconducting cavities (SCs)) and AH1 (8 3.9 GHz SCs), were successfully commissioned by the end of 2015. The commissioning of LLRF stations A2 to A23 (32 1.3 GHz SCs each) in the XFEL accelerator tunnel (XTL) was concluded in June 2017. SASE light was produced in SASE undulator section SA1 and delivered to the first users in September 2017, marking the beginning of regular user operation. The current state of the LLRF systems, the experience gained during operation and the performance achieved in terms of stability and energy reach are presented.

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WEPAK012

Developing Kalman Filter Based Detuning Control with a Digital SRF CW Cavity Simulator

cavity, controls, SRF, FPGA

2114

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

Funding: Work supported by German Bundesministerium für Bildung und Forschung, Land Berlin, and grants of the Helmholtz Association
Continuous wave operated superconducting cavities experiencing small net beam loading and thus operate potentially at narrow bandwidth require precise detuning control to reach the high stability requirements for RF fields within facilities as FEL or ERL based photon sources. Especially microphonics compensation down to sub-hertz detuning regime besides improving stability reduces the risk of rise of Lorentz force detuning driven ponderomotive instabilities. Usually the complex and second order nature of the mechanical to RF detuning transfer functions of cavity and cavity-tuner system require for more advanced control schemes. In this paper we will show the application of a Kalman filter based detuning estimator algorithm first introduced during IPAC2017 [1] to the SRF cavity simulator developed at Helmholtz Zentrum Berlin [2]. Results using the algorithm in observer mode to detuning compensation attempts in closed loop mode are presented.
* A. Ushakov, P. Echevarria, A. Neumann, Proc. of IPAC 2017, Copenhagen, Denmark

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WEPAK013

SRF Cavity Simulator for LLRF Algorithms Debugging

cavity, controls, SRF, FPGA

2118

P. Echevarria, J. Knobloch, A. Neumann, A. Ushakov
HZB, Berlin, Germany
E. Aldekoa, J. Jugo
University of the Basque Country, Faculty of Science and Technology, Bilbao, Spain

Funding: Work supported by German Bundesministerium für Bildung und Forschung, Land Berlin, and grants of Helmholtz Association
The availability of niobium superconducting cavities, ei-ther due to a lack of a real cavity or due to the time needed for the experiment set up (vacuum, cryogenics, cabling, etc.), is limited, and thus it can block or delay the develop-ment of new algorithms such as low level RF control. Hardware-in-the-loop simulations, where an actual cavity is replaced by an electronics system, can help to solve this issue. In this paper we present a Cavity Simulator imple-mented in a National Instruments PXI equipped with an FPGA module. This module operates with one intermedi-ate frequency input which is IQ-demodulated and fed to the electrical cavity's model, where the transmitted and re-flected voltages are calculated and IQ-modulated to gener-ate two intermediate frequency outputs. Some more ad-vanced features such as mechanical vibration modes driven by Lorentz-force detuning or external microphonics have also been implemented. This Cavity Simulator is planned to be connected to an mTCA chassis to close the loop with a LLRF control system.

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WEPAK018

LLRF Control Unit for SuperKEKB Injector Linac

controls, linac, klystron, timing

2134

T. Miura, M. Akemoto, D.A. Arakawa, H. Katagiri, T. Matsumoto, F. Qiu, Y. Yano
KEK, Ibaraki, Japan
N. Liu
Sokendai, Ibaraki, Japan

The low-level RF (LLRF) control unit based on the digital system has been developed for a stable and high precision pulse modulation for the SuperKEKB. The RF pulse is changed at a 50-Hz repetition rate for the top-up injection to four different rings by the event system. The LLRF control unit has not only the pulse modulator, but also other functions: VSWR meter, RF monitor, event receiver (EVR), and pulse-shortening detection.

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WEPAL001

LLRF Control and Master Oscillator System for Damping Ring at SuperKEKB

controls, cavity, injection, linac

2137

T. Kobayashi, K. Akai, A. Kabe, K. Nakanishi, M. Nishiwaki, J.-I. Odagiri
KEK, Ibaraki, Japan
H. Deguchi, K. Hayashi, J. Mizuno
Mitsubishi Electric TOKKI Systems, Amagasaki, Hyogo, Japan
K. Hirosawa
Sokendai, Ibaraki, Japan

For SuperKEKB, new low level RF (LLRF) control systems has ben developed and they worked successfully in the first beam commissioning (Phase-1) of SuperKEKB, which was accomplished in 2016. Damping ring (DR) was newly constructed for positron beam injection, in order to make significantly emittance smaller for SuperKEKB. The beam commissioning of DR will be conducted in JFY2017 for the Phase-2 commissioning. Phase-2 is scheduled in the last quater of JFY2017. DR has an RF station, and two cavities (or three cavities in future) are driven by a klystron. New LLRF control system for DR (DR-LLRF) was also developed and installed. RF frequency of DR operation is common with the main storage rings (MR) of SuperKEKB. The good performance of DR-LLRF was demonstrated in test operation, and RF conditioning of the pair of two cavities was successfully completed in June 2017. This paper reports the detail of the performance results of DR-LLRF controls, and also the other some relevant issues in LLRF controls for DR, including the master oscillator system (synchronization with the injection linac), are introduced.

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WEPAL008

Low-level RF System for The Chinese ADS Front-end Demo Linac

controls, cavity, linac, interface

2159

J.Y. Ma, Z. Gao, G. Huang, L.P. Sun
IMP/CAS, Lanzhou, People's Republic of China

The Chinese ADS Front-end Demo Linac (FDL) is constructed to demonstrate the technology of superconducting linac with high proton beam loading of CW 10mA. The low-level RF (LLRF) control system for the ADS FDL is developed by IMP, and the cooperation with TRIUMF. In the normal conducting (NC) section, the normal RF feedback control loop is used. In order to stable the superconducting (SC) cavity with loaded high RF power, the self excited loop with phase locked mode was used on the SC linac. This paper introduces the LLRF control system for buncher, SC linac, and the structures of hardware and the functions of software of these LLRF systems. The operating status of the LLRF systems is also reported.

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WEPAL010

Review of the ELI-NP-GBS Low Level RF and Synchronization Systems

laser, linac, electron, timing

2162

L. Piersanti, D. Alesini, M. Bellaveglia, F. Cardelli, M. Diomede, A. Gallo, V. Martinelli
INFN/LNF, Frascati (Roma), Italy
B.B. Baricevic, R. Cerne, G. Jug
I-Tech, Solkan, Slovenia
M. Diomede
Sapienza University of Rome, Rome, Italy
P.N. Dominguez
Menlo Systems GmbH, Martinsried, Germany

ELI-NP is a linac based gamma-source in construction at Magurele (RO) by the European consortium EuroGammaS led by INFN. Photons with tunable energy and with intensity and brilliance well beyond the state of the art, will be produced by Compton back-scattering between a high quality electron beam (up to 740 MeV) and a 515 nm intense laser pulse. Production of very intense photon flux with narrow bandwidth requires multi-bunch operation at 100 Hz repetition rate. A total of 13 klystrons, 3 S-band (2856 MHz) and 10 C-band (5712 MHz) will power a total of 14 Travelling Wave accelerating sections (2 S-band and 12 C-band) plus 3 S-band Standing Wave cavities (a 1.6 cell RF gun and 2 RF deflectors). Each klystron is individually driven by a temperature stabilized LLRF module for a maximum flexibility in terms of accelerating gradient, arbitrary pulse shaping (e.g. to compensate beam loading effects in multi-bunch regime) and compensation of long-term thermal drifts. In this paper, the whole LLRF system architecture and bench test results, the RF reference generation and distribution together with an overview of the synchronization system will be described.

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WEPAL017

Adaptive Feedforward Control Design Based on Simulink for the J-PARC LINAC LLRF System

controls, cavity, linac, simulation

2187

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

In j-parc linac, for dealing with high beam loading effect, an adaptive feedforward control method which based on iterative learning control was put forward. At the same time, in order to verify its effectiveness before it is officially put into use, an llrf system simulation model was built in simulink, matlab. In this paper, the architecture of llrf system simulation model will be introduced. The result of iterative learning control (ILC) is summarized.

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WEPAL031

RF Interlock Implementation Using Digital LLRF System for 100 MeV Proton Linac at KOMAC

pick-up, cavity, controls, proton

2233

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 Multi-purpose Accelerator Complex) operation fund of KAERI by MSIT (Ministry of Science and ICT)
KOMAC (Korea Multi-purpose Accelerator Complex) already has operated 100 MeV proton linear accelerator with high availability since 2013. This accelerator is composed of Ion source, LEBT, RFQ and DTL systems to transport proton particles to the target. Total 9 klystrons with 1.6 MWpeak are used to provide controlled RF power to the accelerator cavities with 350 MHz of operating frequency. These klystrons are driven by LLRF systems that the LLRF systems should control the RF and protect the amplifiers and cavities from the abnormal RF. In this article, the RF interlock using cavity pickup signal introduced. When the cavity pickup amplitude breaks away from the adjustable upper or lower limit window, the digital LLRF system interrupts the LLRF output. These implementations were conducted by upgrading the FPGA (Field Programmable Gate Array) logics of the existing digital LLRF system.

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WEPAL039

LCLS-II Gun/Buncher LLRF System Design

gun, cavity, SRF, controls

2258

G. Huang, K.S. Campbell, L.R. Doolittle, J.A. Jones, Q. Qiang, C. Serrano
LBNL, Berkeley, California, USA
S. Babel, A.L. Benwell, M. Boyes, G.W. Brown, D. Cha, J.H. De Long, J.A. Diaz Cruz, B. Hong, A. McCollough, A. Ratti, C.H. Rivetta, D. Rogind, F. Zhou
SLAC, Menlo Park, California, USA
R. Bachimanchi, C. Hovater, D.J. Seidman
JLab, Newport News, Virginia, USA
B.E. Chase, E. Cullerton, J. Einstein-Curtis, D.W. Klepec
Fermilab, Batavia, Illinois, USA
J.A. Diaz Cruz
CSU, Fort Collins, Colorado, USA

Funding: This work was supported by the LCLS-II Project and the U.S. Department of Energy, Contract n. DE-AC02-05CH11231.
For a free electron laser, the stability of injector is critical to the final electron beam parameters, e.g., beam energy, beam arrival time, and eventually it determines the photon quality. The LCLS-II project's injector contains a VHF copper cavity as the gun and a two-cell L-band copper cavity as its buncher. The cavity designs are inherited from the APEX design, but requires more field stability than demonstrated in APEX operation. The gun LLRF system design uses a connectorized RF front end and low noise digitizer, together with the same general purpose FPGA carrier board used in the LCLS-II SRF LLRF system. The buncher LLRF system directly adopts the SRF LLRF chassis design, but programs the controller to run the normal conducting cavities. In this paper, we describe the gun/buncher LLRF system design, including the hardware design, the firmware design and bench test.

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WEPAL040

High Precision Synchronization Development for HiRES, the Ultrafast Electron Diffraction Beamline at LBNL

laser, controls, electron, gun

2262

Y. Yang, K.M. Baptiste, M. Betz, L.R. Doolittle, Q. Du, D. Filippetto, G. Huang, F. Ji
LBNL, Berkeley, California, USA

Precise synchronization between the laser and electron is critical for the pump-probe experiments in the HiRES Ultrafast Electron Diffraction facility. We are upgrading the LLRF and laser control system, which ultimately aims at a synchronization below 50 fs RMS between the pump laser pulse and electron probe at the sample plane. Such target poses tight requirements on the RF field stability both in amplitude and phase, and on the synchronization between the RF field and the laser repetition rate. We are presently developing a new LLRF system that has the potential to decrease the overall noise, reaching the required stability of tens of ppm on RF amplitude and phase. For the laser control side, we are replacing the long coaxial cables with fibers for both control signal transmission and laser signal reception. The control transmission side has been implemented, and the timing jitter has been reduced.

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WEPAL046

A New Digital Feedback and Feedforward Controller for Cavity Field Control of the LANSCE Accelerator

controls, cavity, feedback, FPGA

2277

S. Kwon, L.J. Castellano, D.J. Knapp, J.T.M. Lyles, M.S. Prokop, A. Scheinker, P.A. Torrez
LANL, Los Alamos, New Mexico, USA

Funding: Work Supported by DOE
A new digital low-level RF system was designed and has been deployed on the drift-tube-linac section of the Los Alamos Neutron Science Center(LANSCE) proton accelerator. This new system is part of a modernization of the existing analog cavity-field controls that were originally developed and put into service forty-five years ago. For stabilization of the cavity field amplitude and phase during beam loading, a proportional-integral feedback controller, a static beam feedforward controller, and an iterative learning controller working in parallel have been implemented. In this paper, the controller architecture is described, and the performances of the three controllers when beam is being actively accelerated is presented.

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WEPAL053

Dynamic Signal Analysis Based on FPGA for NSRRC DLLRF

cavity, FPGA, controls, feedback

2295

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

As DLLRF control system designs for SRF cavities have greatly matured and the FPGA technology has im-proved as well, it is possible now to think about incorporating dynamic signal analysis (DSA). Implementation of a DSA in the FPGA is desired to study the frequency response of the open/closed loop gain in a SRF system. Open loop gain is useful to observe the stability of a SRF system while closed loop gain can be applied to investi-gate the operational bandwidth of the system feedback and also to configure the performance of a PID controller. The DSA function was confirmed by analyzing the frequency response of a digital filter and the results of the analysis will be compared with MATLAB simulations.

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WEPAL054

Digital Low Level Radio Frequency System for the Booster Ring of the Taiwan Photon Source

controls, cavity, operation, booster

2298

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 accelerating cavity field amplitude and phase. For the Taiwan Photon Source (TPS) at NSRRC, the currently operating LLRF systems are based on analog technology. To have better RF field stability, precise con-trol and high noise reduction, a digital LLRF control sys-tems based on Field Programmable Gate Arrays (FPGA) was developed. We replaced the analog LLRF system with the digital version for the TPS booster ring at the beginning of 2018, and we will replace those in the storage rings in the future. Test results and operational performance of the TPS booster DLLRF system are reported here.

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WEPMF011

Design and Status of Sirius Light Source RF Systems

cavity, storage-ring, booster, lattice

2391

R.H.A. Farias, A.P.B. Lima, L. Liu, F.S. Oliveira
LNLS, Campinas, Brazil

Sirius is the new synchrotron light source currently under construction at the site of the Brazilian Synchro-tron Light Laboratory (LNLS) in Campinas, Brazil. The facility comprises a 3 GeV electron storage ring, a full energy booster and a 150 MeV linac. This work provides a brief description of the RF system of the booster and storage ring, presenting their main characteristics and specification goals.

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WEPMF054

Design and Status of the MicroTCA.4 Based LLRF System for TARLA

controls, cavity, hardware, operation

2490

Gumus, C. Gumus, M. Hierholzer, K.P. Przygoda, H. Schlarb, Ch. Schmidt
DESY, Hamburg, Germany
A.A. Aksoy, A. Aydin
Ankara University, Accelerator Technologies Institute, Golbasi / Ankara, Turkey

The Turkish Accelerator and Radiation Laboratory in Ankara (TARLA) is constructing a 40 MeV Free Electron Laser with continuous wave (CW) RF operation. In order to control and monitor the four superconducting (SC) TESLA type cavities as well as the two normal conducting (NC) buncher cavities, a MicroTCA.4 based LLRF system is foreseen. This highly modular system is further used to control the mechanical tuning of the SC cavities by control of piezo actuators and mechanical motor tuners. This paper focuses on giving brief overview on hardware and software components of LLRF control of TARLA, as well as updates on the ongoing integration tests at DESY.

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WEPML004

Production Tuner Testing for LCLS-II Cryomodule Production

cavity, cryomodule, interface, SRF

2678

J.P. Holzbauer, Y.M. Pischalnikov, W. Schappert, J.C. Yun
Fermilab, Batavia, Illinois, USA
C. Contreras-Martinez
FRIB, East Lansing, USA

Funding: This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics.
LCLS-II 1.3 GHz cryomodule production is well underway at Fermilab. Several dozen cavity/tuner systems have been tested, including tuning to 1.3 GHz, cold landing frequency, range/sensitivity of the slow tuner, and range/sensitivity of the fast tuner. All this testing information as well as lessons learned from tuner installation will be presented.

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WEPML007

Active Microphonics Compensation for LCLS-II

cavity, controls, resonance, cryomodule

2687

J.P. Holzbauer, B.E. Chase, J. Einstein-Curtis, Y.M. Pischalnikov, W. Schappert
Fermilab, Batavia, Illinois, USA
L.R. Doolittle, C. Serrano
LBNL, Berkeley, California, USA

Funding: This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics.
Testing of early LCLS-II cryomodules showed microphonics-induced detuning levels well above specification. As part of a risk-mitigation effort, a collaboration was formed between SLAC, LBNL, and Fermilab to develop and implement active microphonics compensation into the LCLS-II LLRF system. Compensation was first demonstrated using a Fermilab FPGA-based development system compensating on single cavities, then with the LCLS-II LLRF system on single and multiple cavities simultaneously. The primary technique used for this effort is a bank of narrowband filter set using the piezo-to-detuning transfer function. Compensation automation, optimization, and stability studies were done. Details of the techniques used, firmware/software implementation, and results of these studies will be presented.

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THYGBE3

RF Controls for High-Q Cavities for the LCLS-II

controls, cavity, cryomodule, EPICS

2929

C. Serrano, K.S. Campbell, L.R. Doolittle, G. Huang, A. Ratti
LBNL, Berkeley, California, USA
R. Bachimanchi, C. Hovater
JLab, Newport News, Virginia, USA
A.L. Benwell, M. Boyes, G.W. Brown, D. Cha, G. Dalit, J.A. Diaz Cruz, J. Jones, R.S. Kelly, A. McCollough
SLAC, Menlo Park, California, USA
B.E. Chase, E. Cullerton, J. Einstein-Curtis, J.P. Holzbauer, D.W. Klepec, Y.M. Pischalnikov, W. Schappert
Fermilab, Batavia, Illinois, USA
L.R. Dalesio, M.A. Davidsaver
Osprey DCS LLC, Ocean City, USA

Funding: This work was supported by the LCLS-II Project and the U.S. Department of Energy, Contract n. DE-AC02-76SF00515.
The SLAC National Accelerator Laboratory is building LCLS-II, a new 4 GeV CW superconducting (SCRF) Linac as a major upgrade of the existing LCLS. The LCLS-II Low-Level Radio Frequency (LLRF) collaboration is a multi-lab effort within the Department of Energy (DOE) accelerator complex. The necessity of high longitudinal beam stability of LCLS-II imposes tight amplitude and phase stability requirements on the LLRF system (up to 0.01% in amplitude and 0.01° in phase RMS). This is the first time such requirements are expected of superconducting cavities operating in continuous-wave (CW) mode. Initial measurements on the Cryomodule test stands at partner labs have shown that the early production units are able to meet the extrapolated hardware requirements to achieve such levels of performance. A large effort is currently underway for system integration, Experimental Physics and Industrial Control System (EPICS) controls, transfer of knowledge from the partner labs to SLAC and the production and testing of 76 racks of LLRF equipment.

Slides THYGBE3 [14.383 MB]

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THPAK106

400 MHz Frequency/phase Detector and Counter

detector, controls, FPGA, TRIUMF

3481

X.L. Fu, B. Ji, Z.G. Yin, T.J. Zhang
CIAE, Beijing, People's Republic of China
G. Dennison
UBC & TRIUMF, Vancouver, British Columbia, Canada
K. Fong, M.P. Laverty, Q. Zheng
TRIUMF, Vancouver, Canada

To enhance the performance and precision of TRIUMF Low Level RF system, a frequency/phase detector and counter based on FPGA is developed. The frequency/phase detector and counter is designed as a daughter board of the low level RF control system, and is connected to the mother board with mixed signal connectors. It sends the frequency error data to the PC though VXI databus, and provides two analog phase errors outputs. In current design, one single unit supports four channel discriminations of RF frequencies/phases. Preliminary tests show that the reported phase detector has a bandwidth of 400MHz. A unique implementation of frequency discrimination was carefully carried out to ensure the resolution can reach as high as 1Hz. The phase-frequency detector has been successfully applied to the Accelerator Cryo Module (ACM) system and the requirement of the low level RF control system is satisfied. After a long-term running test, the stability and reliability of the phase-frequency detector are verified.

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THPAL002

RF System Operation of High Current RFQ in ADS Project

rfq, cavity, operation, coupling

3613

L.P. Sun, R. Huang, C.X. Li, L. Lu, A. Shi, L.B. Shi, W.B. Wang, X.B. Xu, H.W. Zhao
IMP/CAS, Lanzhou, People's Republic of China
Y. Hu
TUB, Beijing, People's Republic of China

Funding: Work supported by Natural Science Foundation of China， No.11505253
New RF system has been upgraded several times for high-current operation, especially for extra beam power and detuning angle. The current was increased gradually resulting in more and more frequency detuning, and an effective method is to tune the temperature of cavity to compromise detuning. Of course, the power dissipated in cavity and high intensity beam are approximately 120kW resulting in too many power modules operated in the high risk of failure. The specific analysis and simulation were introduced in detail.

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THPAL004

Research and Development of RF System for SC200 Cyclotron

cavity, cyclotron, simulation, acceleration

3616

G. Chen, C. Chao, G. Liu, X.Y. Long, Z. Peng, Y. Song, Y.S. Wang, C.S. Wei, M. Xu, Q. Yang, X. Zhang, Y. Zhao
ASIPP, Hefei, People's Republic of China
L. Calabretta, A.C. Caruso
INFN/LNS, Catania, Italy
O. Karamyshev, G.A. Karamysheva, N.A. Morozov, E. Samsonov, G. Shirkov
JINR, Dubna, Moscow Region, Russia

A 200MeV compact isochronous superconducting cyclotron, named SC200, for proton therapy is under development by collaboration of ASIPP (Hefei, China) and JINR (Dubna, Russia). The radio frequency (RF) system as one of most significant subsystems in cyclotron consists of acceleration cavity, low level RF, RF source and transmission network. SC200 has two cavities connected in the centre, which are operated at 91.5 MHz with second harmonic. To meet the required acceleration voltage, the cavities have been carefully designed with comprised choices between several aspects, such as Q factor, mechanic stability and so on. The low-level RF (LLRF) system has been implemented by using the FPGA to achieve the significant accelerating voltage with an amplitude stability of <0.2% and a phase stability of < 0.1 degree. The cavity and LLRF system have been tested outside of cyclotron, the results will be presented. For future, the commissioning of whole RF system will be started after the assembly of SC200 at the end of 2019.

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THPAL025

New Drift-Tube Linac RF Systems at LANSCE

DTL, controls, detector, cavity

3680

J.T.M. Lyles, R.E. Bratton, M.S. Prokop, D. Rees
LANL, Los Alamos, New Mexico, USA

Funding: Work supported by the United States Department of Energy, National Nuclear Security Agency, under contract DE-AC52-06NA25396.
LANSCE has restored the proton drift-tube linac (DTL) to high-power capability after the original RF-power tube manufacturer could no longer supply devices that consistently met our high-average power requirement. Thales TH628L Diacrodes® now supply RF power to three of the four DTL tanks. These tetrodes reused the existing infrastructure including water-cooling systems, coaxial transmission lines, high-voltage power supplies and capacitor banks. Each transmitter uses a combined pair of power amplifiers to produce up to 3- MW peak and 360- kW of mean power. A new intermediate power amplifier was simultaneously developed using a TH781 tetrode. Design and prototype testing of the high-power stages was completed in 2012, with commercialization following in 2013. Each installation was accomplished during a 4 to 5 month beam outage each year from 2014-2016. A new digital low-level RF control system was designed, built and placed into operation in 2016. The interaction of the dual power amplifiers, the I/Q LLRF, and the DTL cavities provided many challenges that were overcome. The replacement RF systems have completely met our accelerator requirements.

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THPMF007

Commissioning of the Hybrid Superconducting/Normal Conducting RF System in the Diamond Storage Ring

cavity, storage-ring, operation, HOM

4042

C. Christou, A.G. Day, P. Gu, P.J. Marten, S.A. Pande, D. Spink, A. Tropp
DLS, Oxfordshire, United Kingdom

Two 500 MHz HOM damped normal conducting cavities have been installed in the Diamond storage ring to ensure continuity of operation of Diamond in the event of a failure of one of the two existing superconducting cavities. Following receipt from the manufacturer, the cavities were incorporated into an assembly including vacuum pumping, cooling and interlocked diagnostics and then tested for vacuum integrity and RF performance. Both cavities were then conditioned up to high power in Diamond's RF test facility before being installed in the storage ring in August and November 2017. Conditioning and operation has been carried out using a new digital LLRF system. Results of acceptance tests and commissioning with power and beam are presented, together with the current status of the hybrid RF system and options for further improvement of the system in the near future.

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THPMK064

RF System for SXFEL: C-band, X-band and S-band

FEL, linac, klystron, operation

4446

W. Fang, Q. Gu, X.X. Huang, L. Li, Z.B. Li, J.H. Tan, C.C. Xiao, J.Q. Zhang, Z.T. Zhao
SINAP, Shanghai, People's Republic of China

Shanghai Soft X-ray FEL facility is under commissioning now, which linac is compased of one S-band injector, C-band main linac and X-band linearizer. In SXFEL S-band injector could provide 200MeV beam energy based on 4 RF power unit, and then 6 C-band RF units boost beam energy to 840MeV based on 33MV/m at least, which will be ramped to 40MV/m in the ungrading. In the middle of S-band and C-band RF system, a X-band RF unit is used as linearizer to make energy spread of electron beam linear distribution, which is important for bunch compressor and FEL radiation. In this paper, details of RF system design and status of SXFEL is introduced, and some operation results are presented.

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THPML100

A High Voltage Feedforward Subsystem of Low Level RF System for the High Power RF System

high-voltage, low-level-rf, experiment, controls

4898

Z.Y. Lin, Y. C. Du, H.Q. Feng, W.-H. Huang, CY. Song, C.-X. Tang, Y.L. Xu, J. Yang
TUB, Beijing, People's Republic of China
G. Huang
LBNL, Berkeley, California, USA

The Low Level Radio Frequency control (LLRF) system measures the RF signals from the accelerator tube, compares it with the phase reference received from the timing distribution system, and provides the drive signal to the high power RF system to provide synchronized RF voltage to the electron beam. Usually, the LLRF system can achieve a ~50 fs RMS phase jitter which is limited by the microwave devices. The phase noise arise from the high voltage variation of the high power system will significantly increase phase noise from low level RF signal to high power RF. A high voltage feed forward subsystem is proposed to deal with the phase noise caused by the high voltage jitter of the modulator. The demo system is depolyed in Thomson scattering X-ray source (TTX).and the primary experiment result anaylse is discussed.

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THPML101

A Novel Double Sideband-Based Phase Averaging Line for Phase Reference Distribution System

experiment, laser, FPGA, pick-up

4901

Z.Y. Lin, Y.-C. Du, W.-H. Huang, Z. Pan, C.-X. Tang, C.-X. Tang, Y.L. Xu, J. Yang
TUB, Beijing, People's Republic of China
G. Huang
LBNL, Berkeley, California, USA

Coaxial cable based solution is one of the most important scheme in Phase Reference Distribution System. A novel double sideband-based phase averaging line has been developed in Tsinghua accelerator lab. The sender chassis generates the 2856 MHz signal as the forward signal and receives the 2856 MHz signal and the reflected double sideband signal from the receiver. The forward signal is phase-locked with the reference signal, and the forward signal and the sideband signal are adjusted by the FPGA virtual delay line. The preliminary experiments result shows the phase stability can achieve about 1% by signal distorted by the phase shifter.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML101

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THPML121

Compensation of Transient Beam Loading in Ramping Synchrotrons Using a Fixed Frequency Processing Clock

FPGA, cavity, feedback, synchrotron

4957

F.J. Galindo Guarch, J.M.M.A. Moreno Arostegui
Universitat Politécnica de Catalunya, Barcelona, Spain
P. Baudrenghien, F.J. Galindo Guarch
CERN, Geneva, Switzerland

Transient beam loading compensation schemes, such as One-Turn-FeedBack (OTFB), require beam synchronous processing (BSP). Swept clocks derived from the RF, and therefore harmonic to the revolution frequency, are widely used in CERN synchrotrons; this simplifies implementation with energy ramping, where the revolution frequency changes. It is however not optimal for state-of-the-art digital hardware that prefers fixed frequency clocks. An alternative to the swept clocking is the use of a deterministic protocol, for example, White Rabbit (WR): a fixed reference clock can be extracted from its data stream, while enabling digital distribution of the RF frequency among other data. New algorithms must be developed for BSP using this fixed clock and the digital data transmitted on the WR link. This is the strategy adopted for the SPS Low Level RF (LLRF) upgrade. The paper gives an overview of the technical, technological and historical motivations for such a paradigm evolution. It lists the problems of fixed clock BSP, and presents an innovative solution based on a real-time variable ratio re-sampler for implementing an OTFB with the new fixed clock scheme.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML121

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THPML123

The ESR Barrier-Bucket LLRF System - Design and First Results

cavity, controls, experiment, synchrotron

4964

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

At GSI, Darmstadt, Germany, a Barrier-Bucket (BB) RF System is currently under development for the Experimental Storage Ring (ESR). The system consists of two broadband RF cavities, each driven by a solid state amplifier, with the purpose to produce two voltage pulses per beam revolution. This will enable highly sophisticated longitudinal beam manipulations like longitudinal capture, compression and decompression or stacking of the beam. For the LLRF System, several requirements have to be fulfilled. Besides high standards concerning the pulsed gap signal quality (e.g. ringing <2.5%), the system has to provide the flexibility for adiabatic voltage ramp-up and adiabatic pulse shifting with high timing accuracy. A connection to the FAIR Central Control System (CCS) is necessary, as amplitude and phase ramp data will be provided by the CCS. In this contribution, the structure of the ESR BB LLRF system is presented together with experimental results from the first version of the system, which will be installed in the ESR in March 2018.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML123

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