IPAC2015 - List of Keywords (LLRF)

Paper	Title	Other Keywords	Page
MOPHA021	Bunch-by-Bunch Longitudinal RF Feedback for Beam Stabilization at FAIR	feedback, controls, cavity, synchrotron	820
	K. Groß, H. Klingbeil TEMF, TU Darmstadt, Darmstadt, Germany U. Hartel, H. Klingbeil, U. Laier, D.E.M. Lens, K.-P. Ningel, S. Schäfer, B. Zipfel GSI, Darmstadt, Germany
	Funding: Work supported by the German Federal Ministry of Education and Research (BMBF) under the project 05P12RDRBF. To damp undesired longitudinal oscillations of bunched beams, the main synchrotron SIS100 of FAIR (Facility for Antiproton and Ion Research) will be equipped with a bunch-by-bunch feedback system. This helps to stabilize the beam, to keep longitudinal emittance blow-up low and to minimize beam losses. The proposed LLRF (low level radio frequency) topology of the closed loop feedback system is described. In some aspects, it is similar to the beam phase control system* developed at GSI Helmholtzzentrum für Schwerionenforschung GmbH. The differences and challenges are pointed out, which are mainly the bunch-by-bunch signal processing followed by the generation of a correction voltage in dedicated feedback cavities. The adapted topology was verified at SIS18 during beam time in 2014 using LLRF prototype subsystems and the two existing ferrite-loaded acceleration cavities. The experimental setup to damp coherent longitudinal dipole oscillations is presented and evaluated with focus on the realized modifications, including ongoing and pending investigations. Finally, the current status of the longitudinal feedback system for FAIR is summarized. * Klingbeil et al., IEEE Trans. Nuc. Sci., Vol. 54, No. 6, 2007.
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MOPHA028	Operation of Normal Conducting RF Guns with MicroTCA.4	gun, cavity, feedback, operation	841
	M. Hoffmann, V. Ayvazyan, J. Branlard, L. Butkowski, M.K. Grecki, U. Mavrič, M. Omet, S. Pfeiffer, H. Schlarb, Ch. Schmidt DESY, Hamburg, Germany W. Fornal, R. Rybaniec Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland A. Piotrowski FastLogic Sp. z o.o., Łódź, Poland
	During the last half year, the MicroTCA.4 based single cavity LLRF control system was installed and commissioned at several normal conducting facilities at DESY (FLASH RF gun, REGAE, PITZ RF gun, and XFEL RF gun). First tests during the last year show promising results in optimizing the system for high speed digital LLRF feedbacks, i.e. reducing system latency, increasing the internal controller processing speed, testing new control schemes, and optimizing controller parameters. In this contribution we will present results and gained experience from the commissioning phase and the first time period of real operation.
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MOPHA029	Operation Experiences with the MICROTCA.4-based LLRF Control System at FLASH	operation, electron, radiation, laser	844
	M. Omet, V. Ayvazyan, J. Branlard, L. Butkowski, M.K. Grecki, M. Hoffmann, F. Ludwig, U. Mavrič, S. Pfeiffer, K.P. Przygoda, H. Schlarb, Ch. Schmidt, H.C. Weddig, B.Y. Yang DESY, Hamburg, Germany W. Cichalewski, D.R. Makowski TUL-DMCS, Łódź, Poland K. Czuba, K. Oliwa, I. Rutkowski, R. Rybaniec, D. Sikora, W. Wierba, M. Żukociński Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland A. Piotrowski FastLogic Sp. z o.o., Łódź, Poland
	The Free-Electron Laser in Hamburg (FLASH) at Deutsches Elektronen-Synchrotron (DESY), Hamburg Germany is a user facility providing ultra-short, femtosecond laser pulses up to the soft X-ray wavelength range. For the precise regulation of the radio frequency (RF) fields within the 60 superconducting cavities, which are organized in 5 RF stations, digital low level RF (LLRF) control systems based on the MTCA.4 standard were implemented in 2013. Until now experiences with failures potentially due to radiation, overheating, and ageing as well as with the general operation of the control systems have been gained. These have a direct impact on the operation and on the performance of FLASH and will allow future improvements. The lessons learned are not only important for FLASH but also in the scope of European X-ray Free-Electron Laser (X-FEL), which will be operated with the same LLRF control system.
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MOPHA032	All-Optical Synchronization of Pulsed Laser Systems at FLASH and XFEL	laser, timing, FEL, controls	854
	J.M. Müller, M.K. Czwalinna, M. Felber, M. Schäfer, H. Schlarb, B. Schmidt, S. Schulz, C. Sydlo, F. Zummack DESY, Hamburg, Germany
	The all-optical laser synchronization at FLASH and XFEL provides femtosecond-stable timing of the FEL X-ray photon pulses and associated optical laser pulses (photo-injector laser, seed laser, pump-probe laser, etc.). Based on a two-color balanced optical cross-correlation scheme a high-precision measure of the laser pulse arrival time is delivered, which is used for diagnostic purposes as well as for the active stabilization of the laser systems. In this paper, we present the latest installations of our all-optical synchronization systems at FLASH and the recent developments for the upcoming European XFEL that will ensure a reliable femtosecond-stable timing of FEL and related pulsed laser systems.
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MOPHA045	Developments and Performance of the LLRF System of the S-Band FERMI Linac	klystron, cavity, feedback, controls	891
	A. Fabris, F. Gelmetti, M. Milloch, M. Predonzani Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
	The requirements on beam quality on the FERMI Free Electron Laser (FEL) linac impose challenging specifications on the stability of the RF fields that can only be met by using high reliable and high performance state of the art LLRF systems. The system installed in FERMI has met these requirements and is routinely operational for the machine on a 24/7 basis. The completion of the deployment of the LLRF units in 2015 increases the capabilities of the system, adding further measurement channels and monitoring, and allowing new functionalities. This paper provides an overview of the results achieved with the LLRF system of FERMI and an outlook of the further developments that are being implemented or planned.
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MOPHA047	RF System Design for the TOP-IMPLART Accelerator	controls, proton, klystron, linac	897
	V. Surrenti, G. Bazzano, P. Nenzi, L. Picardi, C. Ronsivalle ENEA C.R. Frascati, Frascati (Roma), Italy F. Ambrosini Università di Roma "La Sapienza", SAPIENZA-DIET, Roma, Italy
	In the ENEA-Frascati research center a linear accelerator for proton therapy is under development in the framework of TOP-IMPLART Project carried out by ENEA in collaboration with ISS and IRE-IFO. The machine is based on a 7 MeV injector operating at a frequency of 425 MHz followed by a sequence of 2997.92 MHz accelerating modules. Five 10 MW klystrons will be used to power all high frequency structures up to a beam energy of 150 MeV. The maximum repetition frequency is 100 Hz and the pulse duration is 4 μs. The RF amplitude and phase stability requirements of the accelerating field are within ±2% and ±2 degrees respectively. For therapeutic use the beam energy will be varied between 85 and 150 MeV by switching off the last modules and varying the electric field amplitude in the last module switched on. Fast control of the RF power supplied to the individual structures allows an energy variation on a pulse by pulse basis; furthermore the system must be able to control the RF phase between accelerating structures. This work describes the RF power distribution scheme and the RF phase and amplitude monitoring system implemented into an embedded control system.
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MOPHA056	Status of LLRF Control System for SuperKEKB Commissioning	controls, cavity, beam-loading, klystron	924
	T. Kobayashi, K. Akai, K. Ebihara, A. Kabe, K. Nakanishi, M. Nishiwaki, J.-I. Odagiri KEK, Ibaraki, Japan H. Deguchi, K. Hayashi, T. Iwaki, M. Ryoshi Mitsubishi Electric TOKKI Systems, Amagasaki, Hyogo, Japan
	Beam commissioning of the SuperKEKB will be started in JFY2015. A new LLRF control system, which is an FPGA-based digital RF feedback control system on the MicroTCA platform, has been developed for high current beam operation of the SuperKEKB. The mass production and installation of the new systems has been completed as scheduled. The new LLRF control systems are applied to nine RF stations (klystron driving units) among existing thirty stations. As a new function, klystron phase lock loop was digitally implemented within the cavity FB control loop in the FPGA, and in the high power test it worked successfully to compensate for the klystron phase change. Beam loading was also simulated in the high power test by using an ARES cavity simulator, and then good performance in the cavity-voltage feedback control and the cavity tuning control was demonstrated to compensate the large beam loading for the SuperKEKB parameters. Fabrication of another new LLRF control system for damping ring which is required for low-emittance positron injection is scheduled in JFY2015.
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MOPTY012	Design and Test of Prototype of LLRF System for KIPT Neutron Source LINAC	controls, linac, EPICS, FPGA	959
	X.P. Ma, Y.L. Chi, R.L. Liu IHEP, Beijing, People's Republic of China S. Shu Institute of High Energy Physics (IHEP), Chinese Academy of Sciences, Beijing, People's Republic of China
	A 100 MeV/100 kW electron LINAC is being constructed by IHEP, China for the NSC KIPT Neutron Source project in Ukraine. A LLRF system is required to produce the driver RF input of the klystron and maintain the accelerating phase and amplitude stability of the machine. The LLRF system consists of an RF reference distribution system, six identical control units, and the fast RF interlock module. The main part of control unit is the PXI-bus crate implemented with PXI9846 - 4 ADC digitizer board and ICS572 - high speed 2 ADC/2 DAC signal process board. An EPICS IOC based on WinDriver as the PCI device driver is developed and tested. Preliminary results show phase detect resolution of 0.03 degree (rms) of 2856 MHz signal has been achieved. *Mail Address: maxp@ihep.ac.cn
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MOPTY013	Control System for DC-SRF Photo-Injector at Peking University	controls, laser, SRF, cryomodule	962
	L.W. Feng, J.K. Hao, S. Huang, L. Lin, K.X. Liu, S.W. Quan, F. Wang, B.C. Zhang PKU, Beijing, People's Republic of China
	A control system has been designed and constructed to full-fill the operation requirement of the DC-SRF photo injector developed at Peking University. The system includes FPGA based low level radio frequency (LLRF) control system, PLC based machine protection system, VME based magnet power control, and PC based EPICS IOC. All these systems were integrated to support the stable operation of the DC-SRF photo injector and has shown their robustness. The LLRF system was optimized and tuned for 2K CW/Pulse operation and the stability of amplitude and phase achieves 0.1% and 0.1° respectively.
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MOPTY042	ALBA LLRF Upgrades to Improve Beam Availability	cavity, beam-loading, operation, synchrotron	1022
	A. Salom, B. Bravo, J. Marcos, F. Pérez ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
	ALBA is a 3GeV synchrotron light source located in Barcelona and operating with users since May 2012. The RF system of the SR is composed of six cavities, each one powered by combining the power of two 80 kW IOTs through a Cavity Combiner (CaCo). At present, there are several RF interlocks per week. The redundancy given by the six cavities makes possible the survival of the beam after one of these trips. In these cases, the cavity has to be recovered with the circulating beam. An autorecovery process has been implemented in the digital LLRF system in order to recover the faulty RF plant after a trip. But these trips also create perturbations to the beam stability. In order to minimize the beam perturbations induced by these RF interlock, an additional feed-forward loop is being implemented. The functionally, main parameters and test results of these new algorithms will be presented.
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MOPTY061	Beam-Based Power Distribution Over Multiple Klystrons in a Linear Accelerator	klystron, high-voltage, linac, controls	1079
	A. Řežaeizadeh, R. Kalt, T. Schilcher PSI, Villigen PSI, Switzerland R. Smith Automatic Control Laboratory, ETH Zurich, Zurich, Switzerland
	A linear accelerator including several klystron driver RF stations can be viewed as a single virtual RF station with a certain accelerating RF voltage (in amplitude and phase). This paper develops an optimization scheme that, for a specified beam energy gain, determines the klystrons output powers and the modulators high voltages optimally. The algorithm employs the klystron nonlinear static characteristics curves to calculate the input RF amplitude of the drive chain. A. Řežaeizadeh, et al, Model-based klystron linearization in the SwissFEL test facility, 36th International Free Electron Laser Conference, Basel, Switzerland
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MOPWI021	The LCLS-II LLRF System	cavity, controls, cryomodule, linac	1195
	C. Hovater, R. Bachimanchi JLab, Newport News, Virginia, USA S. Babel, B. Hong, D. Van Winkle SLAC, Menlo Park, California, USA B.E. Chase, E. Cullerton, P. Varghese Fermilab, Batavia, Illinois, USA L.R. Doolittle, G. Huang, A. Ratti, C. Serrano LBNL, Berkeley, California, 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 (SCRF) linac. The SCRF linac consists of 35 ILC style cryomodules (eight cavities each) for a total of 280 cavities. Expected cavity gradients are 16 MV/m with a loaded QL of ~ 4x10⁷. The RF system will have 3.8 kW solid state amplifiers driving single cavities. To ensure optimum field stability a single source single cavity control system has been chosen. It consists of a precision four channel cavity receiver and RF stations (Forward, Reflected and Drive signals). In order to regulate the resonant frequency variations of the cavities due to He pressure, the tuning of each cavity is controlled by a Piezo actuator and a slow stepper motor. In addition the system (LLRF-amplifier-cavity) is being modeled and cavity microphonic testing has started. This paper describes the LLRF system under consideration, including recent modeling and cavity tests.
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TUAD3	LLRF Commissioning of the European XFEL RF Gun and Its First Linac RF Station	linac, cryomodule, gun, electronics	1377
	J. Branlard, G. Ayvazyan, V. Ayvazyan, L. Butkowski, M.K. Grecki, M. Hoffmann, F. Ludwig, U. Mavrič, M. Omet, S. Pfeiffer, K.P. Przygoda, H. Schlarb, Ch. Schmidt, H.C. Weddig, B.Y. Yang DESY, Hamburg, Germany S. Bou Habib, K. Czuba, M. Grzegrzółka, E. Janas, K. Oliwa, J. Piekarski, K.T. Pozniak, I. Rutkowski, R. Rybaniec, D. Sikora, W. Wierba, L.Z. Zembala, M. Żukociński Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland W. Cichalewski, D.R. Makowski, A. Mielczarek, P. Perek TUL-DMCS, Łódź, Poland A. Piotrowski FastLogic Sp. z o.o., Łódź, Poland
	The European X-ray free electron laser (XFEL) at the Deutsches Elektronen-Synchrotron (DESY), Hamburg Germany is in its construction phase. Approximately a third of the super-conductive cryomodules have been produced and tested. The RF gun is installed since 2013; periods of commissioning are regularly scheduled between installation phases of the rest of the injector. The first linac, L1, consisting of 4 cryomodules powered by one 10 MW klystron is installed and being commissioned. This contribution reports on the installation and preparation work of the low-level radio frequency system (LLRF) to perform the commissioning of the XFEL first components. The commissioning plans, schedule and first results are presented.
	Slides TUAD3 [14.016 MB]
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WEPMA016	A New RF station for the ELSA Stretcher Ring	klystron, cavity, electron, synchrotron	2783
	M. Schedler, A. Dieckmann, P. Hänisch, W. Hillert ELSA, Bonn, Germany
	At the Electron Stretcher Facility ELSA of Bonn University, an increase of the maximum stored beam current from 20 mA to 200 mA is planned. The storage ring operates applying a fast energy ramp of 6 GeV/s from 1.2 GeV to 3.2 GeV and afterwards a slow extraction over a few seconds to the hadron physics experiments. The beam current is mainly limited due to missing RF power at highest energies in order to compensate for synchrotron radiation losses. The current stretcher ring's RF station is based on a single 200 kW klystron driving two 5-cell PETRA type cavities. To achieve the desired beam current at maximum energy two additional 7-cell PETRA type cavities, drivin by a second klystron, will be installed. With this upgrade, sufficient beam lifetime for slow beam extraction will be provided and thus ensure an adequate duty cycle of the external beam current. The general setup of the new RF station as well as the changes in operation when switching from one to two stations will be presented.
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WEPMA024	System Design for a Deterministic Bunch-to-Bucket Transfer	synchrotron, simulation, ion, timing	2809
	T. Ferrand TEMF, TU Darmstadt, Darmstadt, Germany J.N. Bai IAP, Frankfurt am Main, Germany
	Funding: Supported by GSI and the Technical University Darmstadt in the frame of the cooperation for FAIR. A deterministic bunch to bucket transfer system is currently under development in the frame of the FAIR project at GSI. To achieve our accuracy and stability requirements, a set of hardware modules will be implemented. These hardware modules are expected to provide values such as the relative phase advance between the RF systems of both, the source and the target synchrotron according to an external timing system. These values are exchanged via optical fibers between different supply rooms, and the considered RF signals are re-synthesized locally. These re-synthesized signals are synchronized to enable a precise phase advance control between the synchrotrons’ RF systems. The first step of the development consists in modeling the actual DDS and DSP-based LLRF environment of the SIS18 under Ptolemy-II. Measurements on real devices will be performed concurrently to the simulation. We expect to use this simulation to refine our timing expectations regarding the synchronization process and the inter-module communication protocols and design the synchronization function, which will be implemented on the hardware modules.
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WEPMA047	MHI's Production Activities of Accelerator Components	network, status, coupling, vacuum	2873
	N. Shigeoka, S. Miura MHI, Hiroshima, Japan
	Mitsubishi Heavy Industries (MHI) is manufacturing various types of accelerator components. Recent production activities, mainly in a field of a normal conducting RF, will be reported in this presentation.
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WEPMA054	A Disturbance-Observer-based Controller for LLRF Systems	controls, beam-loading, cavity, experiment	2895
	F. Qiu, D.A. Arakawa, Y. Honda, H. Katagiri, T. Matsumoto, S. Michizono, T. Miura, T. Obina KEK, Ibaraki, Japan S.B. Wibowo Sokendai, Ibaraki, Japan
	Digital low-level radio frequency (LLRFs) systems have been developed and evaluated in the compact energy recovery linac (cERL) at KEK. The required RF stabilities are 0.1% rms in amplitude and 0.1° rms in phase. These requirements are satisfied by applying digital LLRF systems. To further enhance the control system and make it robust to disturbances such as large power supply (PS) ripples and high-intensity beams, we have designed and developed a disturbance observer (DOB)-based control method. This method utilizes the RF system model, which can be acquired using modern system identification methods. Experiments show that the proposed DOB-based controller is more effective in the presence of high disturbances compared with the conventional proportional and integral (PI) controller. In this paper, we present the preliminary results based on the experiments with DOB-based controller.
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WEPMA060	The Development of Cavity Frequency Tracking Type RF Control System for SRF-TEM	cavity, SRF, acceleration, electron	2914
	N. Higashi The University of Tokyo, Graduate School of Science, Tokyo, Japan A. Enomoto, Y. Funahashi, T. Furuya, X.J. Jin, Y. Kamiya, S. Michizono, M. Nishiwaki, H. Sakai, M. Sawabe, K. Ueno, M. Yamamoto KEK, Ibaraki, Japan M. Kuriki HU/AdSM, Higashi-Hiroshima, Japan S. Yamashita ICEPP, Tokyo, Japan
	Superconducting accelerating cavities used in high-energy accelerators can generate high electric fields of several 10 MV/m by supplying radio frequency waves (RF) with frequencies matched with resonant frequencies of the cavities. Generally, frequencies of input RFs are fixed, and resonant frequencies of cavities that are fluctuated by Lorentz force detuning and Microphonics are corrected by feedbacks of cavity frequency tuners and input RF power. Now, we aim to develop the cavity frequency tracking type RF control system where the frequency of input RF is not fixed and consistently modulated to match the varying resonant frequency of the cavity. In KEK (Tsukuba, Japan), we are developing SRF-TEM that is a new type of transmission electron microscope using special-shaped superconducting cavity. By applying our new RF control system to the SRF-TEM, it is expected to obtain stable accelerating fields so that we can acquire good spatial resolution. In this presentation, we will explain the required stabilities of accelerating fields for SRF-TEM and the feasibility of SRF-TEM in the case of applying the cavity frequency tracking type RF control system.
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WEPMN030	Testing Procedures for Fast Frequency Tuners of XFEL Cavities	cavity, controls, operation, cryomodule	2991
	K.P. Przygoda, W. Cichalewski, T. Pożniak TUL-DMCS, Łódź, Poland J. Branlard, O. Hensler, H. Schlarb, Ch. Schmidt DESY, Hamburg, Germany K. Kasprzak IFJ-PAN, Kraków, Poland
	The XFEL accelerator will be equipped with 100 accelerating modules. Each accelerating module will host 8 superconducting cavities. Every single cavity will be equipped with a mechanical tuner. Coarse tuning will be supported by a step motor; fine tuning will be handled by double piezoelectric elements installed inside a single mechanical support, providing actuator and sensor functionality or redundancy. Before the main linac installation, all its subcomponents need to be tested and verified. The AMTF (Accelerator Module Test Facility) has been built at DESY to test all XFEL cryomodules. In total 1600 piezos need to be tested. Test procedures for fast frequency tuners have been developed to check their basic performance in cryogenic conditions (tuning range, polarity, acting and sensing abilities). High level applications perform fully automated tests including report generation. After the successful completion of the acceptance tests, the cryomodules will be prepared for tunnel installation.
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WEPMN039	RF Accelerating Voltage of PLS-II Superconducting RF System for Stable Top-up Operation with Beam Current of 400 mA	vacuum, operation, cavity, injection	3015
	Y.D. Joo, M.-H. Chun, T. Ha, I. Hwang, B.-J. Lee, I.S. Park, S. Shin, Y.U. Sohn, I.H. Yu PAL, Pohang, Kyungbuk, Republic of Korea
	During the beam store test up to 400 mA in the storage ring, it was observed that the vacuum pressure around the RF window of the superconducting cavity rapidly increases over the interlock level limiting the availability of the maximum beam current storing. We investigated the cause of the window vacuum pressure increment by studying the changes in the electric field distribution at the superconducting cavity and waveguide according to the beam current. An equivalent physical modeling was developed using a finite-difference time-domain (FDTD) simulation and it revealed that the electric field amplitude at the RF window is exponentially increased as the beam current increases, thus this high electric field amplitude causes a RF breakdown at the RF window.
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WEPMN043	The RF Stability of PLS-II Storage Ring RF System	cavity, controls, EPICS, storage-ring	3024
	I.H. Yu, M.-H. Chun, M.H. Jeong, Y.D. Joo, H.-S. Kang, H.-G. Kim, H.J. Park, I.S. Park, Y.U. Sohn PAL, Pohang, Kyungbuk, Republic of Korea Y.S. Lee SKKU, Suwon, Republic of Korea
	Funding: Minister of Science, ICT and Future Planing The RF system for the Pohang Light Source (PLS) storage ring was greatly upgraded for PLS-II project of 400mA, 3.0GeV from 200mA, 2.5GeV. Three superconducting RF cavities with each 300kW maximum klystron amplifier were commissioned with electron beam in way of one by one during the last 3 years for beam current of 400mA to until March 2014. The RF system is designed to provide stable beam through precise RF phase and amplitude requirements to be less than 0.3% in amplitude and 0.3° in phase deviations. This paper describes the RF system configuration, design details and test results.
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WEPHA045	Design and Construction of the RF Electronic System at Taiwan Photon Source	cavity, booster, controls, detector	3215
	F.-T. Chung, L.-H. Chang, M.H. Chang, L.J. Chen, PY. Chen, M.-C. Lin, Z.K. Liu, C.H. Lo, C.L. Tsai, M.H. Tsai, Ch. Wang, M.-S. Yeh, T.-C. Yu NSRRC, Hsinchu, Taiwan
	The RF electronic system at NSRRC was made fully in house by the RF group from design through construction to completion. The first RF electronic system includes an analogue LLRF system, a step motor, and an ARC module of a Petra cavity. It was successfully integrated with a 100-kW RF transmitter, high-power RF transfer system, and a cooling system and applied to the booster of TPS. Two duplicated RF electronic system were then applied to the storage ring but integrated with the 300-KW transmitters. With these RF systems, the TPS storage ring achieved beam current 100 mA on 2015 March 26.
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MOPHA021

Bunch-by-Bunch Longitudinal RF Feedback for Beam Stabilization at FAIR

feedback, controls, cavity, synchrotron

820

K. Groß, H. Klingbeil
TEMF, TU Darmstadt, Darmstadt, Germany
U. Hartel, H. Klingbeil, U. Laier, D.E.M. Lens, K.-P. Ningel, S. Schäfer, B. Zipfel
GSI, Darmstadt, Germany

Funding: Work supported by the German Federal Ministry of Education and Research (BMBF) under the project 05P12RDRBF.
To damp undesired longitudinal oscillations of bunched beams, the main synchrotron SIS100 of FAIR (Facility for Antiproton and Ion Research) will be equipped with a bunch-by-bunch feedback system. This helps to stabilize the beam, to keep longitudinal emittance blow-up low and to minimize beam losses. The proposed LLRF (low level radio frequency) topology of the closed loop feedback system is described. In some aspects, it is similar to the beam phase control system* developed at GSI Helmholtzzentrum für Schwerionenforschung GmbH. The differences and challenges are pointed out, which are mainly the bunch-by-bunch signal processing followed by the generation of a correction voltage in dedicated feedback cavities. The adapted topology was verified at SIS18 during beam time in 2014 using LLRF prototype subsystems and the two existing ferrite-loaded acceleration cavities. The experimental setup to damp coherent longitudinal dipole oscillations is presented and evaluated with focus on the realized modifications, including ongoing and pending investigations. Finally, the current status of the longitudinal feedback system for FAIR is summarized.
* Klingbeil et al., IEEE Trans. Nuc. Sci., Vol. 54, No. 6, 2007.

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MOPHA028

Operation of Normal Conducting RF Guns with MicroTCA.4

gun, cavity, feedback, operation

841

M. Hoffmann, V. Ayvazyan, J. Branlard, L. Butkowski, M.K. Grecki, U. Mavrič, M. Omet, S. Pfeiffer, H. Schlarb, Ch. Schmidt
DESY, Hamburg, Germany
W. Fornal, R. Rybaniec
Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland
A. Piotrowski
FastLogic Sp. z o.o., Łódź, Poland

During the last half year, the MicroTCA.4 based single cavity LLRF control system was installed and commissioned at several normal conducting facilities at DESY (FLASH RF gun, REGAE, PITZ RF gun, and XFEL RF gun). First tests during the last year show promising results in optimizing the system for high speed digital LLRF feedbacks, i.e. reducing system latency, increasing the internal controller processing speed, testing new control schemes, and optimizing controller parameters. In this contribution we will present results and gained experience from the commissioning phase and the first time period of real operation.

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MOPHA029

Operation Experiences with the MICROTCA.4-based LLRF Control System at FLASH

operation, electron, radiation, laser

844

M. Omet, V. Ayvazyan, J. Branlard, L. Butkowski, M.K. Grecki, M. Hoffmann, F. Ludwig, U. Mavrič, S. Pfeiffer, K.P. Przygoda, H. Schlarb, Ch. Schmidt, H.C. Weddig, B.Y. Yang
DESY, Hamburg, Germany
W. Cichalewski, D.R. Makowski
TUL-DMCS, Łódź, Poland
K. Czuba, K. Oliwa, I. Rutkowski, R. Rybaniec, D. Sikora, W. Wierba, M. Żukociński
Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland
A. Piotrowski
FastLogic Sp. z o.o., Łódź, Poland

The Free-Electron Laser in Hamburg (FLASH) at Deutsches Elektronen-Synchrotron (DESY), Hamburg Germany is a user facility providing ultra-short, femtosecond laser pulses up to the soft X-ray wavelength range. For the precise regulation of the radio frequency (RF) fields within the 60 superconducting cavities, which are organized in 5 RF stations, digital low level RF (LLRF) control systems based on the MTCA.4 standard were implemented in 2013. Until now experiences with failures potentially due to radiation, overheating, and ageing as well as with the general operation of the control systems have been gained. These have a direct impact on the operation and on the performance of FLASH and will allow future improvements. The lessons learned are not only important for FLASH but also in the scope of European X-ray Free-Electron Laser (X-FEL), which will be operated with the same LLRF control system.

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MOPHA032

All-Optical Synchronization of Pulsed Laser Systems at FLASH and XFEL

laser, timing, FEL, controls

854

J.M. Müller, M.K. Czwalinna, M. Felber, M. Schäfer, H. Schlarb, B. Schmidt, S. Schulz, C. Sydlo, F. Zummack
DESY, Hamburg, Germany

The all-optical laser synchronization at FLASH and XFEL provides femtosecond-stable timing of the FEL X-ray photon pulses and associated optical laser pulses (photo-injector laser, seed laser, pump-probe laser, etc.). Based on a two-color balanced optical cross-correlation scheme a high-precision measure of the laser pulse arrival time is delivered, which is used for diagnostic purposes as well as for the active stabilization of the laser systems. In this paper, we present the latest installations of our all-optical synchronization systems at FLASH and the recent developments for the upcoming European XFEL that will ensure a reliable femtosecond-stable timing of FEL and related pulsed laser systems.

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MOPHA045

Developments and Performance of the LLRF System of the S-Band FERMI Linac

klystron, cavity, feedback, controls

891

A. Fabris, F. Gelmetti, M. Milloch, M. Predonzani
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy

The requirements on beam quality on the FERMI Free Electron Laser (FEL) linac impose challenging specifications on the stability of the RF fields that can only be met by using high reliable and high performance state of the art LLRF systems. The system installed in FERMI has met these requirements and is routinely operational for the machine on a 24/7 basis. The completion of the deployment of the LLRF units in 2015 increases the capabilities of the system, adding further measurement channels and monitoring, and allowing new functionalities. This paper provides an overview of the results achieved with the LLRF system of FERMI and an outlook of the further developments that are being implemented or planned.

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MOPHA047

RF System Design for the TOP-IMPLART Accelerator

controls, proton, klystron, linac

897

V. Surrenti, G. Bazzano, P. Nenzi, L. Picardi, C. Ronsivalle
ENEA C.R. Frascati, Frascati (Roma), Italy
F. Ambrosini
Università di Roma "La Sapienza", SAPIENZA-DIET, Roma, Italy

In the ENEA-Frascati research center a linear accelerator for proton therapy is under development in the framework of TOP-IMPLART Project carried out by ENEA in collaboration with ISS and IRE-IFO. The machine is based on a 7 MeV injector operating at a frequency of 425 MHz followed by a sequence of 2997.92 MHz accelerating modules. Five 10 MW klystrons will be used to power all high frequency structures up to a beam energy of 150 MeV. The maximum repetition frequency is 100 Hz and the pulse duration is 4 μs. The RF amplitude and phase stability requirements of the accelerating field are within ±2% and ±2 degrees respectively. For therapeutic use the beam energy will be varied between 85 and 150 MeV by switching off the last modules and varying the electric field amplitude in the last module switched on. Fast control of the RF power supplied to the individual structures allows an energy variation on a pulse by pulse basis; furthermore the system must be able to control the RF phase between accelerating structures. This work describes the RF power distribution scheme and the RF phase and amplitude monitoring system implemented into an embedded control system.

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MOPHA056

Status of LLRF Control System for SuperKEKB Commissioning

controls, cavity, beam-loading, klystron

924

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

Beam commissioning of the SuperKEKB will be started in JFY2015. A new LLRF control system, which is an FPGA-based digital RF feedback control system on the MicroTCA platform, has been developed for high current beam operation of the SuperKEKB. The mass production and installation of the new systems has been completed as scheduled. The new LLRF control systems are applied to nine RF stations (klystron driving units) among existing thirty stations. As a new function, klystron phase lock loop was digitally implemented within the cavity FB control loop in the FPGA, and in the high power test it worked successfully to compensate for the klystron phase change. Beam loading was also simulated in the high power test by using an ARES cavity simulator, and then good performance in the cavity-voltage feedback control and the cavity tuning control was demonstrated to compensate the large beam loading for the SuperKEKB parameters. Fabrication of another new LLRF control system for damping ring which is required for low-emittance positron injection is scheduled in JFY2015.

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MOPTY012

Design and Test of Prototype of LLRF System for KIPT Neutron Source LINAC

controls, linac, EPICS, FPGA

959

X.P. Ma, Y.L. Chi, R.L. Liu
IHEP, Beijing, People's Republic of China
S. Shu
Institute of High Energy Physics (IHEP), Chinese Academy of Sciences, Beijing, People's Republic of China

A 100 MeV/100 kW electron LINAC is being constructed by IHEP, China for the NSC KIPT Neutron Source project in Ukraine. A LLRF system is required to produce the driver RF input of the klystron and maintain the accelerating phase and amplitude stability of the machine. The LLRF system consists of an RF reference distribution system, six identical control units, and the fast RF interlock module. The main part of control unit is the PXI-bus crate implemented with PXI9846 - 4 ADC digitizer board and ICS572 - high speed 2 ADC/2 DAC signal process board. An EPICS IOC based on WinDriver as the PCI device driver is developed and tested. Preliminary results show phase detect resolution of 0.03 degree (rms) of 2856 MHz signal has been achieved.
*Mail Address: maxp@ihep.ac.cn

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MOPTY013

Control System for DC-SRF Photo-Injector at Peking University

controls, laser, SRF, cryomodule

962

L.W. Feng, J.K. Hao, S. Huang, L. Lin, K.X. Liu, S.W. Quan, F. Wang, B.C. Zhang
PKU, Beijing, People's Republic of China

A control system has been designed and constructed to full-fill the operation requirement of the DC-SRF photo injector developed at Peking University. The system includes FPGA based low level radio frequency (LLRF) control system, PLC based machine protection system, VME based magnet power control, and PC based EPICS IOC. All these systems were integrated to support the stable operation of the DC-SRF photo injector and has shown their robustness. The LLRF system was optimized and tuned for 2K CW/Pulse operation and the stability of amplitude and phase achieves 0.1% and 0.1° respectively.

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MOPTY042

ALBA LLRF Upgrades to Improve Beam Availability

cavity, beam-loading, operation, synchrotron

1022

A. Salom, B. Bravo, J. Marcos, F. Pérez
ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain

ALBA is a 3GeV synchrotron light source located in Barcelona and operating with users since May 2012. The RF system of the SR is composed of six cavities, each one powered by combining the power of two 80 kW IOTs through a Cavity Combiner (CaCo). At present, there are several RF interlocks per week. The redundancy given by the six cavities makes possible the survival of the beam after one of these trips. In these cases, the cavity has to be recovered with the circulating beam. An autorecovery process has been implemented in the digital LLRF system in order to recover the faulty RF plant after a trip. But these trips also create perturbations to the beam stability. In order to minimize the beam perturbations induced by these RF interlock, an additional feed-forward loop is being implemented. The functionally, main parameters and test results of these new algorithms will be presented.

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MOPTY061

Beam-Based Power Distribution Over Multiple Klystrons in a Linear Accelerator

klystron, high-voltage, linac, controls

1079

A. Řežaeizadeh, R. Kalt, T. Schilcher
PSI, Villigen PSI, Switzerland
R. Smith
Automatic Control Laboratory, ETH Zurich, Zurich, Switzerland

A linear accelerator including several klystron driver RF stations can be viewed as a single virtual RF station with a certain accelerating RF voltage (in amplitude and phase). This paper develops an optimization scheme that, for a specified beam energy gain, determines the klystrons output powers and the modulators high voltages optimally. The algorithm employs the klystron nonlinear static characteristics curves to calculate the input RF amplitude of the drive chain.
A. Řežaeizadeh, et al, Model-based klystron linearization in the SwissFEL test facility, 36th International Free Electron Laser Conference, Basel, Switzerland

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MOPWI021

The LCLS-II LLRF System

cavity, controls, cryomodule, linac

1195

C. Hovater, R. Bachimanchi
JLab, Newport News, Virginia, USA
S. Babel, B. Hong, D. Van Winkle
SLAC, Menlo Park, California, USA
B.E. Chase, E. Cullerton, P. Varghese
Fermilab, Batavia, Illinois, USA
L.R. Doolittle, G. Huang, A. Ratti, C. Serrano
LBNL, Berkeley, California, 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 (SCRF) linac. The SCRF linac consists of 35 ILC style cryomodules (eight cavities each) for a total of 280 cavities. Expected cavity gradients are 16 MV/m with a loaded QL of ~ 4x10⁷. The RF system will have 3.8 kW solid state amplifiers driving single cavities. To ensure optimum field stability a single source single cavity control system has been chosen. It consists of a precision four channel cavity receiver and RF stations (Forward, Reflected and Drive signals). In order to regulate the resonant frequency variations of the cavities due to He pressure, the tuning of each cavity is controlled by a Piezo actuator and a slow stepper motor. In addition the system (LLRF-amplifier-cavity) is being modeled and cavity microphonic testing has started. This paper describes the LLRF system under consideration, including recent modeling and cavity tests.

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TUAD3

LLRF Commissioning of the European XFEL RF Gun and Its First Linac RF Station

linac, cryomodule, gun, electronics

1377

J. Branlard, G. Ayvazyan, V. Ayvazyan, L. Butkowski, M.K. Grecki, M. Hoffmann, F. Ludwig, U. Mavrič, M. Omet, S. Pfeiffer, K.P. Przygoda, H. Schlarb, Ch. Schmidt, H.C. Weddig, B.Y. Yang
DESY, Hamburg, Germany
S. Bou Habib, K. Czuba, M. Grzegrzółka, E. Janas, K. Oliwa, J. Piekarski, K.T. Pozniak, I. Rutkowski, R. Rybaniec, D. Sikora, W. Wierba, L.Z. Zembala, M. Żukociński
Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland
W. Cichalewski, D.R. Makowski, A. Mielczarek, P. Perek
TUL-DMCS, Łódź, Poland
A. Piotrowski
FastLogic Sp. z o.o., Łódź, Poland

The European X-ray free electron laser (XFEL) at the Deutsches Elektronen-Synchrotron (DESY), Hamburg Germany is in its construction phase. Approximately a third of the super-conductive cryomodules have been produced and tested. The RF gun is installed since 2013; periods of commissioning are regularly scheduled between installation phases of the rest of the injector. The first linac, L1, consisting of 4 cryomodules powered by one 10 MW klystron is installed and being commissioned. This contribution reports on the installation and preparation work of the low-level radio frequency system (LLRF) to perform the commissioning of the XFEL first components. The commissioning plans, schedule and first results are presented.

Slides TUAD3 [14.016 MB]

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WEPMA016

A New RF station for the ELSA Stretcher Ring

klystron, cavity, electron, synchrotron

2783

M. Schedler, A. Dieckmann, P. Hänisch, W. Hillert
ELSA, Bonn, Germany

At the Electron Stretcher Facility ELSA of Bonn University, an increase of the maximum stored beam current from 20 mA to 200 mA is planned. The storage ring operates applying a fast energy ramp of 6 GeV/s from 1.2 GeV to 3.2 GeV and afterwards a slow extraction over a few seconds to the hadron physics experiments. The beam current is mainly limited due to missing RF power at highest energies in order to compensate for synchrotron radiation losses. The current stretcher ring's RF station is based on a single 200 kW klystron driving two 5-cell PETRA type cavities. To achieve the desired beam current at maximum energy two additional 7-cell PETRA type cavities, drivin by a second klystron, will be installed. With this upgrade, sufficient beam lifetime for slow beam extraction will be provided and thus ensure an adequate duty cycle of the external beam current. The general setup of the new RF station as well as the changes in operation when switching from one to two stations will be presented.

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WEPMA024

System Design for a Deterministic Bunch-to-Bucket Transfer

synchrotron, simulation, ion, timing

2809

T. Ferrand
TEMF, TU Darmstadt, Darmstadt, Germany
J.N. Bai
IAP, Frankfurt am Main, Germany

Funding: Supported by GSI and the Technical University Darmstadt in the frame of the cooperation for FAIR.
A deterministic bunch to bucket transfer system is currently under development in the frame of the FAIR project at GSI. To achieve our accuracy and stability requirements, a set of hardware modules will be implemented. These hardware modules are expected to provide values such as the relative phase advance between the RF systems of both, the source and the target synchrotron according to an external timing system. These values are exchanged via optical fibers between different supply rooms, and the considered RF signals are re-synthesized locally. These re-synthesized signals are synchronized to enable a precise phase advance control between the synchrotrons’ RF systems. The first step of the development consists in modeling the actual DDS and DSP-based LLRF environment of the SIS18 under Ptolemy-II. Measurements on real devices will be performed concurrently to the simulation. We expect to use this simulation to refine our timing expectations regarding the synchronization process and the inter-module communication protocols and design the synchronization function, which will be implemented on the hardware modules.

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WEPMA047

MHI's Production Activities of Accelerator Components

network, status, coupling, vacuum

2873

N. Shigeoka, S. Miura
MHI, Hiroshima, Japan

Mitsubishi Heavy Industries (MHI) is manufacturing various types of accelerator components. Recent production activities, mainly in a field of a normal conducting RF, will be reported in this presentation.

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WEPMA054

A Disturbance-Observer-based Controller for LLRF Systems

controls, beam-loading, cavity, experiment

2895

F. Qiu, D.A. Arakawa, Y. Honda, H. Katagiri, T. Matsumoto, S. Michizono, T. Miura, T. Obina
KEK, Ibaraki, Japan
S.B. Wibowo
Sokendai, Ibaraki, Japan

Digital low-level radio frequency (LLRFs) systems have been developed and evaluated in the compact energy recovery linac (cERL) at KEK. The required RF stabilities are 0.1% rms in amplitude and 0.1° rms in phase. These requirements are satisfied by applying digital LLRF systems. To further enhance the control system and make it robust to disturbances such as large power supply (PS) ripples and high-intensity beams, we have designed and developed a disturbance observer (DOB)-based control method. This method utilizes the RF system model, which can be acquired using modern system identification methods. Experiments show that the proposed DOB-based controller is more effective in the presence of high disturbances compared with the conventional proportional and integral (PI) controller. In this paper, we present the preliminary results based on the experiments with DOB-based controller.

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WEPMA060

The Development of Cavity Frequency Tracking Type RF Control System for SRF-TEM

cavity, SRF, acceleration, electron

2914

N. Higashi
The University of Tokyo, Graduate School of Science, Tokyo, Japan
A. Enomoto, Y. Funahashi, T. Furuya, X.J. Jin, Y. Kamiya, S. Michizono, M. Nishiwaki, H. Sakai, M. Sawabe, K. Ueno, M. Yamamoto
KEK, Ibaraki, Japan
M. Kuriki
HU/AdSM, Higashi-Hiroshima, Japan
S. Yamashita
ICEPP, Tokyo, Japan

Superconducting accelerating cavities used in high-energy accelerators can generate high electric fields of several 10 MV/m by supplying radio frequency waves (RF) with frequencies matched with resonant frequencies of the cavities. Generally, frequencies of input RFs are fixed, and resonant frequencies of cavities that are fluctuated by Lorentz force detuning and Microphonics are corrected by feedbacks of cavity frequency tuners and input RF power. Now, we aim to develop the cavity frequency tracking type RF control system where the frequency of input RF is not fixed and consistently modulated to match the varying resonant frequency of the cavity. In KEK (Tsukuba, Japan), we are developing SRF-TEM that is a new type of transmission electron microscope using special-shaped superconducting cavity. By applying our new RF control system to the SRF-TEM, it is expected to obtain stable accelerating fields so that we can acquire good spatial resolution. In this presentation, we will explain the required stabilities of accelerating fields for SRF-TEM and the feasibility of SRF-TEM in the case of applying the cavity frequency tracking type RF control system.

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WEPMN030

Testing Procedures for Fast Frequency Tuners of XFEL Cavities

cavity, controls, operation, cryomodule

2991

K.P. Przygoda, W. Cichalewski, T. Pożniak
TUL-DMCS, Łódź, Poland
J. Branlard, O. Hensler, H. Schlarb, Ch. Schmidt
DESY, Hamburg, Germany
K. Kasprzak
IFJ-PAN, Kraków, Poland

The XFEL accelerator will be equipped with 100 accelerating modules. Each accelerating module will host 8 superconducting cavities. Every single cavity will be equipped with a mechanical tuner. Coarse tuning will be supported by a step motor; fine tuning will be handled by double piezoelectric elements installed inside a single mechanical support, providing actuator and sensor functionality or redundancy. Before the main linac installation, all its subcomponents need to be tested and verified. The AMTF (Accelerator Module Test Facility) has been built at DESY to test all XFEL cryomodules. In total 1600 piezos need to be tested. Test procedures for fast frequency tuners have been developed to check their basic performance in cryogenic conditions (tuning range, polarity, acting and sensing abilities). High level applications perform fully automated tests including report generation. After the successful completion of the acceptance tests, the cryomodules will be prepared for tunnel installation.

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WEPMN039

RF Accelerating Voltage of PLS-II Superconducting RF System for Stable Top-up Operation with Beam Current of 400 mA

vacuum, operation, cavity, injection

3015

Y.D. Joo, M.-H. Chun, T. Ha, I. Hwang, B.-J. Lee, I.S. Park, S. Shin, Y.U. Sohn, I.H. Yu
PAL, Pohang, Kyungbuk, Republic of Korea

During the beam store test up to 400 mA in the storage ring, it was observed that the vacuum pressure around the RF window of the superconducting cavity rapidly increases over the interlock level limiting the availability of the maximum beam current storing. We investigated the cause of the window vacuum pressure increment by studying the changes in the electric field distribution at the superconducting cavity and waveguide according to the beam current. An equivalent physical modeling was developed using a finite-difference time-domain (FDTD) simulation and it revealed that the electric field amplitude at the RF window is exponentially increased as the beam current increases, thus this high electric field amplitude causes a RF breakdown at the RF window.

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WEPMN043

The RF Stability of PLS-II Storage Ring RF System

cavity, controls, EPICS, storage-ring

3024

I.H. Yu, M.-H. Chun, M.H. Jeong, Y.D. Joo, H.-S. Kang, H.-G. Kim, H.J. Park, I.S. Park, Y.U. Sohn
PAL, Pohang, Kyungbuk, Republic of Korea
Y.S. Lee
SKKU, Suwon, Republic of Korea

Funding: Minister of Science, ICT and Future Planing
The RF system for the Pohang Light Source (PLS) storage ring was greatly upgraded for PLS-II project of 400mA, 3.0GeV from 200mA, 2.5GeV. Three superconducting RF cavities with each 300kW maximum klystron amplifier were commissioned with electron beam in way of one by one during the last 3 years for beam current of 400mA to until March 2014. The RF system is designed to provide stable beam through precise RF phase and amplitude requirements to be less than 0.3% in amplitude and 0.3° in phase deviations. This paper describes the RF system configuration, design details and test results.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMN043

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WEPHA045

Design and Construction of the RF Electronic System at Taiwan Photon Source

cavity, booster, controls, detector

3215

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

The RF electronic system at NSRRC was made fully in house by the RF group from design through construction to completion. The first RF electronic system includes an analogue LLRF system, a step motor, and an ARC module of a Petra cavity. It was successfully integrated with a 100-kW RF transmitter, high-power RF transfer system, and a cooling system and applied to the booster of TPS. Two duplicated RF electronic system were then applied to the storage ring but integrated with the 300-KW transmitters. With these RF systems, the TPS storage ring achieved beam current 100 mA on 2015 March 26.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPHA045

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reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)