IPAC2016 - List of Keywords (LLRF)

Paper	Title	Other Keywords	Page
MOPMB058	Bunch Arrival Time Monitor Test at PAL-XFEL ITF	pick-up, cavity, simulation, resonance	223
	J.H. Hong, J.H. Han, C. Kim, H. Yang PAL, Pohang, Kyungbuk, Republic of Korea
	Femtosecond resolution electron bunch arrival time monitor (BAM) will be required for the beam-based RF phase feedback during PAL-XFEL operation. Two S-band cavity-type BAMs were manufactured for the test at the PAL-XFEL injector test facility (ITF). The resonance frequencies of the cavities are 2856 MHz and 2826.25 MHz. Electron beam induced signal from the cavities was digitized using a low level RF (LLRF) module. In this paper, the resolution of these cavities are analyzed and a possible improvement for better resolution are discussed.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMB058
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MOPMW006	The RF System of the ELI-NP Gamma Beam Source	linac, electron, klystron, network	407
	L. Piersanti, F. Cardelli, L. Palumbo INFN-Roma1, Rome, Italy D. Alesini, M. Bellaveglia, R. Boni, A. Gallo, A. Variola INFN/LNF, Frascati (Roma), Italy F. Cardelli, L. Palumbo, L. Piersanti University of Rome La Sapienza, Rome, Italy G. D'Auria Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
	ELI-NP is a linac based gamma-source under construction in Magurele (RO) by the European consortium EuroGammaS led by INFN. Photons with tunable energy (from 0.2 to 19.5 MeV) and with unprecedented intensity and brilliance will be produced by Compton back-scattering between a high quality electron beam (up to 740 MeV), and a 515 nm intense laser pulse. In order to increase the gamma photon flux, the accelerator will operate in multi-bunch at 100 Hz repetition rate, with 32 bunches separated by 16 ns. Three S-band (2856 MHz) RF power plants will feed two room temperature Travelling Wave (TW) structures, a 1.6 cell Standing Wave (SW) S-band gun (which has been manufactured by means of a new technique based on clamped gaskets without brazing) and two SW RF deflectors for longitudinal beam diagnostics. Ten C-band (5712 MHz) RF power plants will feed 12 TW high-order-modes (HOM) damped structures. In this paper, we review the whole ELI-NP RF architecture including the Low Level RF (LLRF) system.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMW006
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MOPMW009	RF System of the SPring-8 Upgrade Project	storage-ring, klystron, linac, synchrotron	414
	H. Ego, T. Fujita, N. Hosoda, K. Kobayashi, T. Masuda, S. Matsubara, T. Sugimoto JASRI/SPring-8, Hyogo-ken, Japan T. Asaka, T. Fukui, T. Inagaki, C. Kondo, H. Maesaka, T. Ohshima, T. Sakurai RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
	The RF system of the SPring-8 storage ring has stably generated an accelerating voltage of 16 MV at a frequency of 508.58 MHz since 1997. In the upgrade of the SPring-8, a beam energy is lowered from 8 to 6 GeV and a needed voltage is 7 MV. The upgrade employs multi-bending optics, and shortens the straight sections available for RF accelerating cavities by 30%. On account of the space, the RF system is to be so rearranged that the number of cavities can be reduced to half. The analog low-level RF (LLRF) system in use controls the voltage with sufficiently small deviations of less than 0.1 % in amplitude and less than 0.1 degree in phase, but becomes out-of-dates and hard to be maintained. We plan to replace them with a compact digital LLRF system in the MTCA.4 standard and based on under-sampling scheme. The SACLA linac is used for injecting a low-emittance beam to the ring. Because we have to balance the FEL operation and the beam injection on demand, pulse-by-pulse control of beam parameters is going to be implemented to the SACLA LLRF modules. Furthermore, we build a timing system for injection to a target bucket-position in the ring within a time deviation of 3 ps.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMW009
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MOPMW019	Resonant Frequency Control with RCCS for the KOMAC Proton Linac	controls, DTL, linac, proton	435
	D.H. Seo, Y.-S. Cho, H.S. Kim, H.-J. Kwon, K.T. Seol, Y.G. Song Korea Atomic Energy Research Institute (KAERI), Gyeongbuk, Republic of Korea
	Funding: This work is supported by the Ministry of Science, ICT & Future Planning of the Korean Government. The Resonance control cooling systems (RCCS) of 100 MeV proton linac at the Korea multi-purpose accelerator complex (KOMAC) have been operated for cooling the drift tubes (DT) and controlling the resonant frequency of the drift tube linac (DTL). The RCCS can maintain the cooling water temperature within ±0.1 °C by controlling 3-way valve opening. The RCCS has two types of control mode, the constant cooling water temperature control mode and the resonant frequency control mode. In the case of the resonant frequency control, the error frequency is measured in the low-level RF (LLRF) control system and the RCCS compensates the error frequency by controlling the cooling water temperature of DT with PID algorithm. In this paper, the operation results of the resonant frequency control with the RCCS as well as some modification of the LLRF system are presented.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMW019
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MOPMY002	Simulation and Experimental Studies of a 2.45GHz Magnetron Source for an SRF Cavity with Field Amplitude and Phase Controls	controls, cavity, injection, SRF	514
	H. Wang, T. E. Plawski, R.A. Rimmer JLab, Newport News, Virginia, USA A. Dudas, M.L. Neubauer Muons, Inc, Illinois, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177 and NP STTR Grant DE-SC0013203. Phase lock to an SRF cavity by using injection signal through output waveguide of a magnetron has been demonstrated [1, 3]. Amplitude control using magnetic field trimming and anode voltage modulation has been studied using MATLAB/Simulink simulations [2]. Based on these, we are planning to use an FPGA based digital LLRF system, which allows applying various types of control algorithms in order to achieve the required accelerating field stability. Since the 1497 MHz magnetron is still in the design stage, the proof of principle measurements of a commercial 2450 MHz magnetron are carried out to characterize the anode I-V curve, output power (the tube electronic efficiency), frequency dependence on the anode current (frequency pushing) and the Rieke diagram (frequency pulling by the reactive load). Based on early Simulink simulation, experimental data and extension of the Adler equation governing injection phase stability by Chen's model, the specification of the new LLRF control chassis for both 2450 and 1497MHz systems are presented in this paper.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMY002
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MOPMY011	LLRF System Performance during SC Cavity Conditioning at STF KEK	cavity, controls, feedback, FPGA	536
	S.B. Wibowo Sokendai, Ibaraki, Japan T. Matsumoto, S. Michizono, T. Miura, F. Qiu KEK, Ibaraki, Japan
	High Energy Accelerator Research Organization (KEK) is now developing a digital low-level radio frequency (LLRF) control system based on digital feedback control at superconducting RF test facility (STF). The goal is to achieve the amplitude and phase stability of the accelerating field in the superconducting accelerator. Testing and evaluation of the digital LLRF system were conducted during the cavity conditioning performed between October and December 2015 to determine the level of performance. To enable cavity signal monitoring, direct sampling system was constructed and evaluated.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMY011
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MOPMY023	High Power Test of the RF System for the KOMAC MEBT	controls, DTL, FPGA, proton	552
	S.G. Kim, Y.-S. Cho, H.S. Kim, H.-J. Kwon Korea Atomic Energy Research Institute (KAERI), Gyeongbuk, Republic of Korea Y.G. Song KAERI, Gyeongbuk, Republic of Korea
	Funding: This work has been supported through KOMAC (Korea Multi-purpose Accelerator Complex) operation fund of KAERI by MSIP (Ministry of Science, ICT and Future Planning) A 100 MeV proton linac of the Korea multi-purpose accelerator complex (KOMAC) has been operated for providing a proton beam to users. RF systems of two medium energy beam transports (MEBT) have been designed to improve a beam quality. An operating frequency of the MEBT RF system is 350 MHz, and the required RF power is 44 kW for MEBT-1 and 18 kW for MEBT-2. The RF duty is 9% (1.5 ms, 60 Hz), and an RF stability of ±1% in amplitude and ±1° in phase is required. The RF system includes a low-level RF (LLRF) control system, a solid state RF amplifier (SSPA) as a 60 kW SSPA for MEBT-1 and a 30 kW SSPA for MEBT-2, a coaxial circulator, and 3-1/8" coaxial line components. A RF power test to the MEBT has been performed with 4 kW SSPA before the full power operation. The configuration and high power test results of the MEBT RF system are presented in this paper.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMY023
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MOPMY026	Development of an X-Band Linearizer System for PAL-XFEL	klystron, electron, acceleration, wakefield	554
	H. Heo, J. Hu, H.-S. Kang, K.H. Kim, S.H. Kim, H.-S. Lee, B.G. Oh, S.S. Park, Y.J. Park, Y.J. Suh PAL, Pohang, Kyungbuk, Republic of Korea
	We developed an X-band RF system for the linear bunch compression in the PAL-XFEL. We installed a SLAC X-band accelerating structure on a precise mover stage and applied RF power by using a SLAC XL-4 11.424 GHz klystron driven by an inverter charging type modulator. We are developing a solid state amplifier controlled by an X-band LLRF system instead of using a TWTA as a driving RF source for the klystron. We present and discuss the recent test results of the system.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMY026
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MOPMY033	Effect of Bandwidth of Low Level Radio Frequency System on the Instability of an Electron Beam	feedback, cavity, synchrotron, electron	570
	Z.K. Liu, L.-H. Chang, M.H. Chang, L.J. Chen, PY. Chen, F.-T. Chung, M.-C. Lin, C.H. Lo, C.L. Tsai, M.H. Tsai, Ch. Wang, M.-S. Yeh, T.-C. Yu NSRRC, Hsinchu, Taiwan
	The analog Low Level Radio Frequency (LLRF) system is used at Taiwan Photon Source (TPS) RF system. It is composed of three feedback loops to control the amplitude and phase of accelerating field and the frequency of RF cavity. Instability of electron beam and accelerating field due to the bandwidth of LLRF system were observed during the TPS commissioning. This effect was studied and the results will be presented in this paper.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMY033
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MOPOY030	Superconducting Cavity Phase and Amplitude Measurement in Low Energy Accelerating Section	cavity, linac, beam-transport, superconducting-cavity	919
	C. Meng, H. Geng, F. Yan, Y.L. Zhao IHEP, Beijing, People's Republic of China
	Superconducting linear accelerator is the tendency in linac design with the development of superconducting RF technology. Superconducting cavities used as accelerating section in low energy Hadron linac are more and more common. The 5MeV test stand of CADS accelerator Injector I is composed of an ion source, a LEBT, a 325MHz RFQ, a MEBT, a cryogenic module (CM1) of seven SC spoke cavities (β=0.12) , seven SC solenoids, seven cold BPMs and a beam dump. The phase and amplitude setting of superconducting cavity are very important at the operation of accelerator, so beam based measurement of cavity phase and amplitude is necessary. Beam based phase scan is the most simple and effective method. Because the significant velocity changes in superconducting cavity at low energy section, the effective voltage is changing with cavity phase, meanwhile the synchronous phase is non-linear with LLRF phase. Above two problem make the cavity phase determination difficult. New date fitting method is proposed to solve these problem in this paper. Some measurements of spoke cavities in the CADS CM1 are also presented.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOY030
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MOPOY051	Manufacturing and the LLRF Tests of the SANAEM RFQ	rfq, cavity, vacuum, simulation	964
	G. Turemen, Y. Akgun, A. Alacakir, A.S. Bolukdemir, I. Kilic, B. Yasatekin TAEK - SANAEM, Ankara, Turkey G. Unel UCI, Irvine, California, USA H. Yildiz Istanbul University, Istanbul, Turkey
	Funding: Turkish Atomic Energy Authority Turkish Atomic Energy Authority is working on building an experimental proton beamline with local resources at the Saraykoy Nuclear Research and Training Center (SANAEM). Manufacturing of the radio frequency quadrupole (RFQ) was started after the beam dynamics and 3D electromagnetic simulation studies were performed. The vanes were machined with a three axis CNC machine. A CMM was used for the acceptance tests of the vanes and also for assembling. Production and assembly results were found acceptable for this cavity, the very first one developed in Turkey. Copper plating was performed by electroplating the aluminum vanes. The plated vanes were bolted and bonded with eight screws, eight pins and two different adhesives. A silver paste was used for RF sealing and a low vapor pressure epoxy was used for vacuum isolation. First LLRF tests of the RFQ were done with a bead-pull setup and a VNA. A N-type RF coupler and a pick-up were used for the LLRF tests. Phase shift method was used for the bead-pull tests. Cavity quality factor was measured with 3dB method for different RF sealing stages. This study summarizes the machining, assembling and the first LLRF tests of the SANAEM RFQ.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOY051
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TUPOR028	Excitation of Longitudinal Coupled-bunch Oscillations with the Wide-band Cavity in the CERN PS	cavity, feedback, synchrotron, proton	1724
	L. Ventura, M. Migliorati INFN-Roma1, Rome, Italy H. Damerau, M. Migliorati, G. Sterbini CERN, Geneva, Switzerland M. Migliorati University of Rome "La Sapienza", Rome, Italy
	Longitudinal coupled-bunch oscillations in the CERN Proton Synchrotron have been studied in the past years and they have been recognized as one of the major challenges to reach the high brightness beam required by the High Luminosity LHC project. In the frame of the LHC Injectors Upgrade project in 2014 a new wide-band Finemet cavity has been installed in the Proton Synchrotron as a part of the coupled-bunch feedback system. To explore the functionality of the Finemet cavity during 2015 a dedicated measurement campaign has been performed. Coupled-bunch oscillations have been excited with the cavity around each harmonic of the revolution frequency with both a uniform and nominal filling pattern. In the following the measurements procedure and results are presented.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOR028
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WEPOR033	Progress in the Work on the Tuner Control System of the cERL at KEK	controls, feedback, linac, FPGA	2742
	F. Qiu, T. Matsumoto, S. Michizono, T. Miura KEK, Ibaraki, Japan S.B. Wibowo Sokendai, Ibaraki, Japan
	A compact energy recovery linac (cERL), which is a test machine for future 3 GeV ERL project, was constructed at KEK. Five superconducting (SC) cavities were installed in the injector and main linac of the cERL. The SC cavities in cERL are prone to detuning by disturbances such as microphonics. Therefore, a piezo-based tuner system was used to compensate for the detuning of the SC cavity in the cERL. We have proposed advanced control methods that aim at improving the performance of the cERL tuner systems. In this paper, we present the progress in our work on the cERL tuner systems. The preliminary results of the beam-commissioning are also presented.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOR033
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WEPOR034	Design and Evaluation of a Broad Band microTCA.4 Based Downconverter	controls, radio-frequency, laser, electron	2746
	N. Gan, Y.L. Chi, R.L. Liu, X. Ma IHEP, Beijing, People's Republic of China
	Modern low-level RF (LLRF) control systems of particle accelerators are designed to achieve extremely precise field amplitude and phase regulation inside the accelerating cavities, the RF field signal is usually converted to an intermediate frequency (IF) before being sampled by ADC. As the down-conversion is an important procedure of the digital signal processing in LLRF system, designing a high performance and broad band downconverter compatible with various accelerators will be significant. In this paper, the design of a MicroTCA based downconverter is presented, the major design objective of this module is wider operating frequency range and more flexibility in application. Several performance evaluations on different frequency points of this module have been conducted and the module presents a good performance in the operating frequency range.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOR034
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WEPOR035	MicroTCA.4-Based LLRF System for Spoke Cavities of C-ADS Injector I	cavity, operation, controls, cryomodule	2749
	X. Ma, N. Gan, X. Huang, N. Liu, R.L. Liu, G.W. Wang, Q.Y. Wang IHEP, Beijing, People's Republic of China H.Y. Lin Institute of High Energy Physics (IHEP), Chinese Academy of Sciences, Beijing, People's Republic of China
	The C-ADS Injector I is being built in IHEP, which includes 14 β=0.12 superconducting single spoke cavities enclosed with two cryomodules under 2 K. The MicroTCA.4-based Low Level RF (LLRF) system provides GDR mode for the operation of the cavities. The LLRF system supports both CW and duty-adjustable pulsed operation modes for the high power source and the cavities. The firmware of the FPGA controller and the EPICS IOC software has been upgraded during the last half year adding feedforward and abnormal detection. The operator interface (OPI) software and automatic operation script are also described. The MicroTCA.4 platform runs well for the beam commissioning of the Injector I. Some gained experiences with stable beam operation are also shown.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOR035
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WEPOR036	Design and Commissioning of LLRF System for ADS Project in China	controls, cavity, operation, proton	2752
	R.L. Liu, Y.L. Chi, N. Gan, X. Huang, N. Liu, X. Ma, Z.H. Mi, G.W. Wang, Q.Y. Wang, S.Z. Wang, Z.S. Zhou IHEP, Beijing, People's Republic of China H.Y. Lin Institute of High Energy Physics (IHEP), Chinese Academy of Sciences, Beijing, People's Republic of China
	This article describes a low-level RF control system for the ADS project at IHEP, which includes control units for an RFQ, 2 Bunchers and 14 spoke superconducting cavities with the reference line distribution. The paper covers system design consideration and implementation for those units. we will also presented some experience and results for the last one year operation of these LLRF systems.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOR036
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WEPOR037	Beam Loading Effects in SSRF Storage Ring	feedback, cavity, storage-ring, beam-loading	2755
	Y. Xia, Q. Chang, Z. Li, K. Xu, Zh.G. Zhang, S.J. Zhao, Y.B. Zhao, X. Zheng SINAP, Shanghai, People's Republic of China
	The beam current in the storage ring of Shanghai Synchrotron Radiation Facility (SSRF) is now normally 240 mA and projected to be raised to 300 mA. Heavy beam loading will be serious and associated Robinson instability needs to be compressed. In this paper, the beam loading effects in SSRF storage ring and methods to increase current limit will be discussed. .
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOR037
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WEPOR039	Development of 200 MHz Digital LLRF System for the 1 MeV/n RFQ at KOMAC	controls, rfq, cavity, FPGA	2758
	H.S. Jeong, T.S. Ahn, Y.-S. Cho, H.S. Kim, S.G. Kim, H.-J. Kwon Korea Atomic Energy Research Institute (KAERI), Gyeongbuk, Republic of Korea Y.G. Song KAERI, Daejon, Republic of Korea
	KOMAC (Korea Multi-purpose Accelerator Complex) has a plan to develop the multipurpose ion irradiation system. This system includes the ion source, LEBT, RFQ and MEBT systems to transport ion particles to the target. In particular, the RFQ (Radio Frequency Quadrupole) system should receive 200 MHz RF within 1% amplitude error stability. To supply stable 200 MHz RF signal to the RFQ cavity, the LLRF (Low-Level Radio Frequency) system should be controlled through a control system which implemented using commercial digital board. This 1 MeV/n RFQ LLRF system has a concept to minimize the number of the analog components for minimizing the control error. For this, the FPGA (Field Programmable Gate Array) in the digital board will control the frequency of the output sinusoidal signal. In addition, this LLRF system applied the direct sampling, Non-IQ sampling, direct RF generation and fast IQ set update rate algorithm. In this presentation, the FPGA control logics of the LLRF digital board will be introduced. Also, the LLRF PI control logic test using 200 MHz dummy cavity will be described.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOR039
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WEPOR040	LLRF Development for PAL-XFEL	operation, klystron, electron, feedback	2761
	J. Hu, W.H. Hwang, H.-S. Kang, H.-S. Lee, C.-K. Min, G. Mun PAL, Pohang, Kyungbuk, Republic of Korea J.H. Chang, J.S. Han, Y.S. Kim RFPT, Gyeonggi-do, Republic of Korea O.J. Kim, H.S. Lee Mobiis Co., Ltd., Seoul, Republic of Korea
	PAL-XFEL construction is completed. Now, beam commissioning is ongoing after RF conditioning. The LLRF and SSA systems installed and in normal operation are presented. Those structures, features, characteristics, and performances are described.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOR040
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WEPOR042	LLRF Control of High Loaded-Q Cavities for the LCLS-II	cavity, controls, feedback, linac	2765
	C. Serrano, L.R. Doolittle, G. Huang, A. Ratti LBNL, Berkeley, California, USA S. Babel, M. Boyes, B. Hong SLAC, Menlo Park, California, USA R. Bachimanchi, C. Hovater JLab, Newport News, Virginia, USA B.E. Chase, E. Cullerton, J. Einstein Fermilab, Batavia, Illinois, USA
	Funding: This work was supported by the LCLS-II Project and the U.S. Department of Energy, Contract DE-AC02-76SF00515 The SLAC National Accelerator Laboratory is planning an upgrade (LCLS-II) to the Linear Coherent Light Source with a 4 GeV CW Superconducting Radio Frequency (SCRF) linac. The nature of the machine places stringent requirements in the Low-Level RF (LLRF) system, expected to control the cavity fields within 0.01 degrees in phase and 0.01% in amplitude, which is equivalent to a longitudinal motion of the cavity structure in the nanometer range. This stability has been achieved in the past but never for hundreds of superconducting cavities in Continuous-Wave (CW) operation. The difficulty resides in providing the ability to reject disturbances from the cryomodule, which is incompletely known as it depends on the cryomodule structure itself (currently under development at JLab and Fermilab) and the harsh accelerator environment. Previous experience in the field and an extrapolation to the cavity design parameters (relatively high Q_Lc≈ 4×10⁷ , implying a half-bandwidth of around 16 Hz) suggest the use of strong RF feedback to reject the projected noise disturbances, which in turn demands careful engineering of the entire system.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOR042
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WEPOR044	Fpga Implementation of a Control System for the LANSCE Accelerator	controls, feedback, cavity, FPGA	2771
	S. Kwon, L.J. Castellano, D.J. Knapp, J.T.M. Lyles, M.S. Prokop, D. Rees, A. Scheinker, P.A. Torrez LANL, Los Alamos, New Mexico, USA
	As part of the modernization of the Los Alamos Neutron Science Center (LANSCE), a digital low level RF (LLRF) system was designed. The LLRF control system was implemented in a Field Programmable Gate Array (FPGA) using embedded Experimental Physics and Industrial Control System (EPICS) Input Output Controller (IOC) under the Real-Time Executive for Multiprocessor Systems (RTEMS). Proportional-Integral (PI) feedback controller, static beam feedforward controller, and iterative learning controller are implemented on the FPGA. The closed loop system performance was tested with a 10mA peak current proton beam.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOR044
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WEPOY002	A Time Domain Analysis Method for RF Noise	simulation, cavity, experiment, beam-loading	2994
	L. Lin, B. Du, G. Huang, Y.T. Liu USTC/NSRL, Hefei, Anhui, People's Republic of China
	A time domain analysis method is developed for the calculation of the longitudinal oscillations caused by the RF noise in the storage ring. This method is based on the impulse response model, and it could calculates the change of transient field caused by beam oscillation and RF noise turn by turn. By means of discrete spectrum analysis, the spectrum of the beam is obtained. According to this analysis method, we developed a simulation pro-gram. The synchronous oscillation of the excited by high RF source with a phase modulation is predicted in this program, and the corresponding experimental measure-ments are carried out on HLS II. The fitting results are in agreed with the experimental measurements.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOY002
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THOBA01	RF Pinger Commissioning and Beam Dynamics Studies at NSLS-II	cavity, synchrotron, dynamic-aperture, controls	3161
	G.M. Wang, B. Holub, Y. Li, J. Rose, T.V. Shaftan, V.V. Smaluk BNL, Upton, Long Island, New York, USA
	Funding: DOE contract DE-SC0012704 NSLS II storage ring RF system has the digital ramp control function, enabling rapid change of the cavity phase and amplitude. This, together with largely overcoupled RF cavity and transmitter geometry, enables the possibility to "ping" the beam in longitudinal phase space. Similar to the pinger commonly used for transverse beam dynamic studies, the RF jump presents with a powerful tool for investigation of the machine longitudinal beam dynamics. During our beam studies, RF phase was jumped within a short interval of time (less than synchrotron period). Using turn-by-turn data from BPMs we measured the machine energy acceptance with and without damping wigglers. This paper presents the beam study results.
	Slides THOBA01 [4.365 MB]
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THOBA01
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THPOY057	RF Timing Distribution and Laser Synchronization Commissioning of PAL-XFEL	timing, laser, linac, FEL	4234
	C.-K. Min, S.H. Jung, H.-S. Kang, C. Kim, I.S. Ko, S.J. Park PAL, Pohang, Kyungbuk, Republic of Korea
	PAL-XFEL requires <100 fs synchronization of LLRF systems and optical lasers for stable operation and even lower jitter is favorable in higher performance and pump-probe experiments. The RF timing distribution system is based on a 476 MHz reference line, which is converted to 2.856 GHz at 16 locations over 1.5 km distance using phase-locked DRO. The 2.856 GHz signals are amplified and split to 10 outputs, which is connected to LLRFs, BAMs, and DCMs through low timing drift cables. The jitter between two different PLDRO units is estimated to ~1 fs from 1 Hz to 1 MHz. The synchronization jitter between a Ti:sapphire laser and the 2.856 GHz signal is measured less than 20 fs.
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THPOY059	Synchronization System for Tsinghua Thomson Scattering X-ray Source	laser, controls, scattering, low-level-rf	4237
	J. Yang, Y.-C. Du, W.-H. Huang, D. Wang, L.X. Yan TUB, Beijing, People's Republic of China J.M. Byrd, L.R. Doolittle, Q. Du, G. Huang, R.B. Wilcox, Y.L. Xu LBNL, Berkeley, California, USA
	Tsinghua Thomson scattering X-ray Source (TTX) generates X-ray based on inverse thomson scattering method. The synchronization system for TTX includes reference distribution, normal conducting cavity Low Level RF control and Laser-RF synchronization. In collaboration with LBNL, we're working on a prototype synchronization system for TTX. Some test result based on Tsinghua Thomson scattering X-ray Source were obtained. In this paper we will show the synchronization system design and preliminary test result.
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Paper

Title

Other Keywords

Page

MOPMB058

Bunch Arrival Time Monitor Test at PAL-XFEL ITF

pick-up, cavity, simulation, resonance

223

J.H. Hong, J.H. Han, C. Kim, H. Yang
PAL, Pohang, Kyungbuk, Republic of Korea

Femtosecond resolution electron bunch arrival time monitor (BAM) will be required for the beam-based RF phase feedback during PAL-XFEL operation. Two S-band cavity-type BAMs were manufactured for the test at the PAL-XFEL injector test facility (ITF). The resonance frequencies of the cavities are 2856 MHz and 2826.25 MHz. Electron beam induced signal from the cavities was digitized using a low level RF (LLRF) module. In this paper, the resolution of these cavities are analyzed and a possible improvement for better resolution are discussed.

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MOPMW006

The RF System of the ELI-NP Gamma Beam Source

linac, electron, klystron, network

407

L. Piersanti, F. Cardelli, L. Palumbo
INFN-Roma1, Rome, Italy
D. Alesini, M. Bellaveglia, R. Boni, A. Gallo, A. Variola
INFN/LNF, Frascati (Roma), Italy
F. Cardelli, L. Palumbo, L. Piersanti
University of Rome La Sapienza, Rome, Italy
G. D'Auria
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy

ELI-NP is a linac based gamma-source under construction in Magurele (RO) by the European consortium EuroGammaS led by INFN. Photons with tunable energy (from 0.2 to 19.5 MeV) and with unprecedented intensity and brilliance will be produced by Compton back-scattering between a high quality electron beam (up to 740 MeV), and a 515 nm intense laser pulse. In order to increase the gamma photon flux, the accelerator will operate in multi-bunch at 100 Hz repetition rate, with 32 bunches separated by 16 ns. Three S-band (2856 MHz) RF power plants will feed two room temperature Travelling Wave (TW) structures, a 1.6 cell Standing Wave (SW) S-band gun (which has been manufactured by means of a new technique based on clamped gaskets without brazing) and two SW RF deflectors for longitudinal beam diagnostics. Ten C-band (5712 MHz) RF power plants will feed 12 TW high-order-modes (HOM) damped structures. In this paper, we review the whole ELI-NP RF architecture including the Low Level RF (LLRF) system.

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MOPMW009

RF System of the SPring-8 Upgrade Project

storage-ring, klystron, linac, synchrotron

414

H. Ego, T. Fujita, N. Hosoda, K. Kobayashi, T. Masuda, S. Matsubara, T. Sugimoto
JASRI/SPring-8, Hyogo-ken, Japan
T. Asaka, T. Fukui, T. Inagaki, C. Kondo, H. Maesaka, T. Ohshima, T. Sakurai
RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan

The RF system of the SPring-8 storage ring has stably generated an accelerating voltage of 16 MV at a frequency of 508.58 MHz since 1997. In the upgrade of the SPring-8, a beam energy is lowered from 8 to 6 GeV and a needed voltage is 7 MV. The upgrade employs multi-bending optics, and shortens the straight sections available for RF accelerating cavities by 30%. On account of the space, the RF system is to be so rearranged that the number of cavities can be reduced to half. The analog low-level RF (LLRF) system in use controls the voltage with sufficiently small deviations of less than 0.1 % in amplitude and less than 0.1 degree in phase, but becomes out-of-dates and hard to be maintained. We plan to replace them with a compact digital LLRF system in the MTCA.4 standard and based on under-sampling scheme. The SACLA linac is used for injecting a low-emittance beam to the ring. Because we have to balance the FEL operation and the beam injection on demand, pulse-by-pulse control of beam parameters is going to be implemented to the SACLA LLRF modules. Furthermore, we build a timing system for injection to a target bucket-position in the ring within a time deviation of 3 ps.

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MOPMW019

Resonant Frequency Control with RCCS for the KOMAC Proton Linac

controls, DTL, linac, proton

435

D.H. Seo, Y.-S. Cho, H.S. Kim, H.-J. Kwon, K.T. Seol, Y.G. Song
Korea Atomic Energy Research Institute (KAERI), Gyeongbuk, Republic of Korea

Funding: This work is supported by the Ministry of Science, ICT & Future Planning of the Korean Government.
The Resonance control cooling systems (RCCS) of 100 MeV proton linac at the Korea multi-purpose accelerator complex (KOMAC) have been operated for cooling the drift tubes (DT) and controlling the resonant frequency of the drift tube linac (DTL). The RCCS can maintain the cooling water temperature within ±0.1 °C by controlling 3-way valve opening. The RCCS has two types of control mode, the constant cooling water temperature control mode and the resonant frequency control mode. In the case of the resonant frequency control, the error frequency is measured in the low-level RF (LLRF) control system and the RCCS compensates the error frequency by controlling the cooling water temperature of DT with PID algorithm. In this paper, the operation results of the resonant frequency control with the RCCS as well as some modification of the LLRF system are presented.

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MOPMY002

Simulation and Experimental Studies of a 2.45GHz Magnetron Source for an SRF Cavity with Field Amplitude and Phase Controls

controls, cavity, injection, SRF

514

H. Wang, T. E. Plawski, R.A. Rimmer
JLab, Newport News, Virginia, USA
A. Dudas, M.L. Neubauer
Muons, Inc, Illinois, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177 and NP STTR Grant DE-SC0013203.
Phase lock to an SRF cavity by using injection signal through output waveguide of a magnetron has been demonstrated [1, 3]. Amplitude control using magnetic field trimming and anode voltage modulation has been studied using MATLAB/Simulink simulations [2]. Based on these, we are planning to use an FPGA based digital LLRF system, which allows applying various types of control algorithms in order to achieve the required accelerating field stability. Since the 1497 MHz magnetron is still in the design stage, the proof of principle measurements of a commercial 2450 MHz magnetron are carried out to characterize the anode I-V curve, output power (the tube electronic efficiency), frequency dependence on the anode current (frequency pushing) and the Rieke diagram (frequency pulling by the reactive load). Based on early Simulink simulation, experimental data and extension of the Adler equation governing injection phase stability by Chen's model, the specification of the new LLRF control chassis for both 2450 and 1497MHz systems are presented in this paper.

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MOPMY011

LLRF System Performance during SC Cavity Conditioning at STF KEK

cavity, controls, feedback, FPGA

536

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

High Energy Accelerator Research Organization (KEK) is now developing a digital low-level radio frequency (LLRF) control system based on digital feedback control at superconducting RF test facility (STF). The goal is to achieve the amplitude and phase stability of the accelerating field in the superconducting accelerator. Testing and evaluation of the digital LLRF system were conducted during the cavity conditioning performed between October and December 2015 to determine the level of performance. To enable cavity signal monitoring, direct sampling system was constructed and evaluated.

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MOPMY023

High Power Test of the RF System for the KOMAC MEBT

controls, DTL, FPGA, proton

552

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

Funding: This work has been supported through KOMAC (Korea Multi-purpose Accelerator Complex) operation fund of KAERI by MSIP (Ministry of Science, ICT and Future Planning)
A 100 MeV proton linac of the Korea multi-purpose accelerator complex (KOMAC) has been operated for providing a proton beam to users. RF systems of two medium energy beam transports (MEBT) have been designed to improve a beam quality. An operating frequency of the MEBT RF system is 350 MHz, and the required RF power is 44 kW for MEBT-1 and 18 kW for MEBT-2. The RF duty is 9% (1.5 ms, 60 Hz), and an RF stability of ±1% in amplitude and ±1° in phase is required. The RF system includes a low-level RF (LLRF) control system, a solid state RF amplifier (SSPA) as a 60 kW SSPA for MEBT-1 and a 30 kW SSPA for MEBT-2, a coaxial circulator, and 3-1/8" coaxial line components. A RF power test to the MEBT has been performed with 4 kW SSPA before the full power operation. The configuration and high power test results of the MEBT RF system are presented in this paper.

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MOPMY026

Development of an X-Band Linearizer System for PAL-XFEL

klystron, electron, acceleration, wakefield

554

H. Heo, J. Hu, H.-S. Kang, K.H. Kim, S.H. Kim, H.-S. Lee, B.G. Oh, S.S. Park, Y.J. Park, Y.J. Suh
PAL, Pohang, Kyungbuk, Republic of Korea

We developed an X-band RF system for the linear bunch compression in the PAL-XFEL. We installed a SLAC X-band accelerating structure on a precise mover stage and applied RF power by using a SLAC XL-4 11.424 GHz klystron driven by an inverter charging type modulator. We are developing a solid state amplifier controlled by an X-band LLRF system instead of using a TWTA as a driving RF source for the klystron. We present and discuss the recent test results of the system.

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MOPMY033

Effect of Bandwidth of Low Level Radio Frequency System on the Instability of an Electron Beam

feedback, cavity, synchrotron, electron

570

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

The analog Low Level Radio Frequency (LLRF) system is used at Taiwan Photon Source (TPS) RF system. It is composed of three feedback loops to control the amplitude and phase of accelerating field and the frequency of RF cavity. Instability of electron beam and accelerating field due to the bandwidth of LLRF system were observed during the TPS commissioning. This effect was studied and the results will be presented in this paper.

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MOPOY030

Superconducting Cavity Phase and Amplitude Measurement in Low Energy Accelerating Section

cavity, linac, beam-transport, superconducting-cavity

919

C. Meng, H. Geng, F. Yan, Y.L. Zhao
IHEP, Beijing, People's Republic of China

Superconducting linear accelerator is the tendency in linac design with the development of superconducting RF technology. Superconducting cavities used as accelerating section in low energy Hadron linac are more and more common. The 5MeV test stand of CADS accelerator Injector I is composed of an ion source, a LEBT, a 325MHz RFQ, a MEBT, a cryogenic module (CM1) of seven SC spoke cavities (β=0.12) , seven SC solenoids, seven cold BPMs and a beam dump. The phase and amplitude setting of superconducting cavity are very important at the operation of accelerator, so beam based measurement of cavity phase and amplitude is necessary. Beam based phase scan is the most simple and effective method. Because the significant velocity changes in superconducting cavity at low energy section, the effective voltage is changing with cavity phase, meanwhile the synchronous phase is non-linear with LLRF phase. Above two problem make the cavity phase determination difficult. New date fitting method is proposed to solve these problem in this paper. Some measurements of spoke cavities in the CADS CM1 are also presented.

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MOPOY051

Manufacturing and the LLRF Tests of the SANAEM RFQ

rfq, cavity, vacuum, simulation

964

G. Turemen, Y. Akgun, A. Alacakir, A.S. Bolukdemir, I. Kilic, B. Yasatekin
TAEK - SANAEM, Ankara, Turkey
G. Unel
UCI, Irvine, California, USA
H. Yildiz
Istanbul University, Istanbul, Turkey

Funding: Turkish Atomic Energy Authority
Turkish Atomic Energy Authority is working on building an experimental proton beamline with local resources at the Saraykoy Nuclear Research and Training Center (SANAEM). Manufacturing of the radio frequency quadrupole (RFQ) was started after the beam dynamics and 3D electromagnetic simulation studies were performed. The vanes were machined with a three axis CNC machine. A CMM was used for the acceptance tests of the vanes and also for assembling. Production and assembly results were found acceptable for this cavity, the very first one developed in Turkey. Copper plating was performed by electroplating the aluminum vanes. The plated vanes were bolted and bonded with eight screws, eight pins and two different adhesives. A silver paste was used for RF sealing and a low vapor pressure epoxy was used for vacuum isolation. First LLRF tests of the RFQ were done with a bead-pull setup and a VNA. A N-type RF coupler and a pick-up were used for the LLRF tests. Phase shift method was used for the bead-pull tests. Cavity quality factor was measured with 3dB method for different RF sealing stages. This study summarizes the machining, assembling and the first LLRF tests of the SANAEM RFQ.

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TUPOR028

Excitation of Longitudinal Coupled-bunch Oscillations with the Wide-band Cavity in the CERN PS

cavity, feedback, synchrotron, proton

1724

L. Ventura, M. Migliorati
INFN-Roma1, Rome, Italy
H. Damerau, M. Migliorati, G. Sterbini
CERN, Geneva, Switzerland
M. Migliorati
University of Rome "La Sapienza", Rome, Italy

Longitudinal coupled-bunch oscillations in the CERN Proton Synchrotron have been studied in the past years and they have been recognized as one of the major challenges to reach the high brightness beam required by the High Luminosity LHC project. In the frame of the LHC Injectors Upgrade project in 2014 a new wide-band Finemet cavity has been installed in the Proton Synchrotron as a part of the coupled-bunch feedback system. To explore the functionality of the Finemet cavity during 2015 a dedicated measurement campaign has been performed. Coupled-bunch oscillations have been excited with the cavity around each harmonic of the revolution frequency with both a uniform and nominal filling pattern. In the following the measurements procedure and results are presented.

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WEPOR033

Progress in the Work on the Tuner Control System of the cERL at KEK

controls, feedback, linac, FPGA

2742

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

A compact energy recovery linac (cERL), which is a test machine for future 3 GeV ERL project, was constructed at KEK. Five superconducting (SC) cavities were installed in the injector and main linac of the cERL. The SC cavities in cERL are prone to detuning by disturbances such as microphonics. Therefore, a piezo-based tuner system was used to compensate for the detuning of the SC cavity in the cERL. We have proposed advanced control methods that aim at improving the performance of the cERL tuner systems. In this paper, we present the progress in our work on the cERL tuner systems. The preliminary results of the beam-commissioning are also presented.

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WEPOR034

Design and Evaluation of a Broad Band microTCA.4 Based Downconverter

controls, radio-frequency, laser, electron

2746

N. Gan, Y.L. Chi, R.L. Liu, X. Ma
IHEP, Beijing, People's Republic of China

Modern low-level RF (LLRF) control systems of particle accelerators are designed to achieve extremely precise field amplitude and phase regulation inside the accelerating cavities, the RF field signal is usually converted to an intermediate frequency (IF) before being sampled by ADC. As the down-conversion is an important procedure of the digital signal processing in LLRF system, designing a high performance and broad band downconverter compatible with various accelerators will be significant. In this paper, the design of a MicroTCA based downconverter is presented, the major design objective of this module is wider operating frequency range and more flexibility in application. Several performance evaluations on different frequency points of this module have been conducted and the module presents a good performance in the operating frequency range.

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WEPOR035

MicroTCA.4-Based LLRF System for Spoke Cavities of C-ADS Injector I

cavity, operation, controls, cryomodule

2749

X. Ma, N. Gan, X. Huang, N. Liu, R.L. Liu, G.W. Wang, Q.Y. Wang
IHEP, Beijing, People's Republic of China
H.Y. Lin
Institute of High Energy Physics (IHEP), Chinese Academy of Sciences, Beijing, People's Republic of China

The C-ADS Injector I is being built in IHEP, which includes 14 β=0.12 superconducting single spoke cavities enclosed with two cryomodules under 2 K. The MicroTCA.4-based Low Level RF (LLRF) system provides GDR mode for the operation of the cavities. The LLRF system supports both CW and duty-adjustable pulsed operation modes for the high power source and the cavities. The firmware of the FPGA controller and the EPICS IOC software has been upgraded during the last half year adding feedforward and abnormal detection. The operator interface (OPI) software and automatic operation script are also described. The MicroTCA.4 platform runs well for the beam commissioning of the Injector I. Some gained experiences with stable beam operation are also shown.

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WEPOR036

Design and Commissioning of LLRF System for ADS Project in China

controls, cavity, operation, proton

2752

R.L. Liu, Y.L. Chi, N. Gan, X. Huang, N. Liu, X. Ma, Z.H. Mi, G.W. Wang, Q.Y. Wang, S.Z. Wang, Z.S. Zhou
IHEP, Beijing, People's Republic of China
H.Y. Lin
Institute of High Energy Physics (IHEP), Chinese Academy of Sciences, Beijing, People's Republic of China

This article describes a low-level RF control system for the ADS project at IHEP, which includes control units for an RFQ, 2 Bunchers and 14 spoke superconducting cavities with the reference line distribution. The paper covers system design consideration and implementation for those units. we will also presented some experience and results for the last one year operation of these LLRF systems.

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WEPOR037

Beam Loading Effects in SSRF Storage Ring

feedback, cavity, storage-ring, beam-loading

2755

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

The beam current in the storage ring of Shanghai Synchrotron Radiation Facility (SSRF) is now normally 240 mA and projected to be raised to 300 mA. Heavy beam loading will be serious and associated Robinson instability needs to be compressed. In this paper, the beam loading effects in SSRF storage ring and methods to increase current limit will be discussed. .

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WEPOR039

Development of 200 MHz Digital LLRF System for the 1 MeV/n RFQ at KOMAC

controls, rfq, cavity, FPGA

2758

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

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

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WEPOR040

LLRF Development for PAL-XFEL

operation, klystron, electron, feedback

2761

J. Hu, W.H. Hwang, H.-S. Kang, H.-S. Lee, C.-K. Min, G. Mun
PAL, Pohang, Kyungbuk, Republic of Korea
J.H. Chang, J.S. Han, Y.S. Kim
RFPT, Gyeonggi-do, Republic of Korea
O.J. Kim, H.S. Lee
Mobiis Co., Ltd., Seoul, Republic of Korea

PAL-XFEL construction is completed. Now, beam commissioning is ongoing after RF conditioning. The LLRF and SSA systems installed and in normal operation are presented. Those structures, features, characteristics, and performances are described.

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WEPOR042

LLRF Control of High Loaded-Q Cavities for the LCLS-II

cavity, controls, feedback, linac

2765

C. Serrano, L.R. Doolittle, G. Huang, A. Ratti
LBNL, Berkeley, California, USA
S. Babel, M. Boyes, B. Hong
SLAC, Menlo Park, California, USA
R. Bachimanchi, C. Hovater
JLab, Newport News, Virginia, USA
B.E. Chase, E. Cullerton, J. Einstein
Fermilab, Batavia, Illinois, USA

Funding: This work was supported by the LCLS-II Project and the U.S. Department of Energy, Contract DE-AC02-76SF00515
The SLAC National Accelerator Laboratory is planning an upgrade (LCLS-II) to the Linear Coherent Light Source with a 4 GeV CW Superconducting Radio Frequency (SCRF) linac. The nature of the machine places stringent requirements in the Low-Level RF (LLRF) system, expected to control the cavity fields within 0.01 degrees in phase and 0.01% in amplitude, which is equivalent to a longitudinal motion of the cavity structure in the nanometer range. This stability has been achieved in the past but never for hundreds of superconducting cavities in Continuous-Wave (CW) operation. The difficulty resides in providing the ability to reject disturbances from the cryomodule, which is incompletely known as it depends on the cryomodule structure itself (currently under development at JLab and Fermilab) and the harsh accelerator environment. Previous experience in the field and an extrapolation to the cavity design parameters (relatively high Q_Lc≈ 4×10⁷ , implying a half-bandwidth of around 16 Hz) suggest the use of strong RF feedback to reject the projected noise disturbances, which in turn demands careful engineering of the entire system.

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WEPOR044

Fpga Implementation of a Control System for the LANSCE Accelerator

controls, feedback, cavity, FPGA

2771

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

As part of the modernization of the Los Alamos Neutron Science Center (LANSCE), a digital low level RF (LLRF) system was designed. The LLRF control system was implemented in a Field Programmable Gate Array (FPGA) using embedded Experimental Physics and Industrial Control System (EPICS) Input Output Controller (IOC) under the Real-Time Executive for Multiprocessor Systems (RTEMS). Proportional-Integral (PI) feedback controller, static beam feedforward controller, and iterative learning controller are implemented on the FPGA. The closed loop system performance was tested with a 10mA peak current proton beam.

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reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOR044

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WEPOY002

A Time Domain Analysis Method for RF Noise

simulation, cavity, experiment, beam-loading

2994

L. Lin, B. Du, G. Huang, Y.T. Liu
USTC/NSRL, Hefei, Anhui, People's Republic of China

A time domain analysis method is developed for the calculation of the longitudinal oscillations caused by the RF noise in the storage ring. This method is based on the impulse response model, and it could calculates the change of transient field caused by beam oscillation and RF noise turn by turn. By means of discrete spectrum analysis, the spectrum of the beam is obtained. According to this analysis method, we developed a simulation pro-gram. The synchronous oscillation of the excited by high RF source with a phase modulation is predicted in this program, and the corresponding experimental measure-ments are carried out on HLS II. The fitting results are in agreed with the experimental measurements.

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reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOY002

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THOBA01

RF Pinger Commissioning and Beam Dynamics Studies at NSLS-II

cavity, synchrotron, dynamic-aperture, controls

3161

G.M. Wang, B. Holub, Y. Li, J. Rose, T.V. Shaftan, V.V. Smaluk
BNL, Upton, Long Island, New York, USA

Funding: DOE contract DE-SC0012704
NSLS II storage ring RF system has the digital ramp control function, enabling rapid change of the cavity phase and amplitude. This, together with largely overcoupled RF cavity and transmitter geometry, enables the possibility to "ping" the beam in longitudinal phase space. Similar to the pinger commonly used for transverse beam dynamic studies, the RF jump presents with a powerful tool for investigation of the machine longitudinal beam dynamics. During our beam studies, RF phase was jumped within a short interval of time (less than synchrotron period). Using turn-by-turn data from BPMs we measured the machine energy acceptance with and without damping wigglers. This paper presents the beam study results.

Slides THOBA01 [4.365 MB]

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reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THOBA01

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THPOY057

RF Timing Distribution and Laser Synchronization Commissioning of PAL-XFEL

timing, laser, linac, FEL

4234

C.-K. Min, S.H. Jung, H.-S. Kang, C. Kim, I.S. Ko, S.J. Park
PAL, Pohang, Kyungbuk, Republic of Korea

PAL-XFEL requires <100 fs synchronization of LLRF systems and optical lasers for stable operation and even lower jitter is favorable in higher performance and pump-probe experiments. The RF timing distribution system is based on a 476 MHz reference line, which is converted to 2.856 GHz at 16 locations over 1.5 km distance using phase-locked DRO. The 2.856 GHz signals are amplified and split to 10 outputs, which is connected to LLRFs, BAMs, and DCMs through low timing drift cables. The jitter between two different PLDRO units is estimated to ~1 fs from 1 Hz to 1 MHz. The synchronization jitter between a Ti:sapphire laser and the 2.856 GHz signal is measured less than 20 fs.

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reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOY057

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THPOY059

Synchronization System for Tsinghua Thomson Scattering X-ray Source

laser, controls, scattering, low-level-rf

4237

J. Yang, Y.-C. Du, W.-H. Huang, D. Wang, L.X. Yan
TUB, Beijing, People's Republic of China
J.M. Byrd, L.R. Doolittle, Q. Du, G. Huang, R.B. Wilcox, Y.L. Xu
LBNL, Berkeley, California, USA

Tsinghua Thomson scattering X-ray Source (TTX) generates X-ray based on inverse thomson scattering method. The synchronization system for TTX includes reference distribution, normal conducting cavity Low Level RF control and Laser-RF synchronization. In collaboration with LBNL, we're working on a prototype synchronization system for TTX. Some test result based on Tsinghua Thomson scattering X-ray Source were obtained. In this paper we will show the synchronization system design and preliminary test result.

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reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOY059

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