IPAC2014 - Classification: 07 Accelerator Technology Main Systems / T27 Low Level RF

Paper	Title	Page
WEPME062	A New Digital LLRF System for a Fast Ramping Storage Ring	2418
	M. Schedler, F. Frommberger, W. Hillert, D. Proft, D. Sauerland ELSA, Bonn, Germany D. Teytelman Dimtel, San Jose, USA
	At the Electron Stretcher Facility ELSA of Bonn University, an upgrade 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 3.5 GeV and a slow extraction afterwards over a few seconds to the hadron physics experiments. The intended upgrade is mainly limited by the coupled-bunch instabilities and the ability of bunch-by-bunch feedback systems to suppress such instabilities. In order to achieve optimum bunch-by-bunch feedback performance, the beam phase with respect to the master oscillator and the synchrotron frequency have to stay constant. This paper reports on a new high performance low level RF (LLRF) system. The system stabilizes the cavity field and is capable of executing fast voltage and phase ramps. The LLRF uses FPGA-based digital signal processing and includes cavity tuner control as well as fast interlocks and extensive diagnostics.
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WEPME063	Pulsed Low Level Baseband RF Control of CH-Cavities for p-Linac at FAIR	2421
	P. Nonn, U. Bonnes, C. Burandt, F. Hug, N. Pietralla TU Darmstadt, Darmstadt, Germany H. Klingbeil, G. Schreiber, W. Vinzenz GSI, Darmstadt, Germany H. Klingbeil TEMF, TU Darmstadt, Darmstadt, Germany
	Funding: This project was supported by the BMBF under grant No. 05P09RDRB5 and by the Helmholtz International Center for FAIR (HIC for FAIR) funded by the State of Hesse within its LOEWE initiative. At the Facility for Antiproton and Ion Research (FAIR) in Darmstadt, Germany a high intensity antiproton beam will be produced. To provide the necessary 70 mA proton beam a dedicated proton linac (p-Linac) is under construction. The main acceleration will be provided by 9 novel CH-type cavities, of which 6 will be coupled in pairs to share the same klystron. To test the rf properties of these novel cavities, a test stand is under construction. An rf control system for the pulsed operation of these cavities has been developed at TU Darmstadt. It is based upon the digital cw rf control that is successfully in operation as part of the S-DALINAC at IKP Darmstadt. The latest developments will be presented.
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WEPME064	Comparison of an Analytical Model for Lossy Transmission Lines with Measurement Data	2424
SUSPSNE108	use link to see paper's listing under its alternate paper code
	N. Schmitt TEMF, TU Darmstadt, Darmstadt, Germany H. Klingbeil GSI, Darmstadt, Germany
	This paper deals with the analytical modeling of lossy coaxial transmission lines in the frequency range from 100 kHz to 50 MHz with focus on corrugated coaxial lines with polyethylene foam as dielectric. The considered transmission lines are used in low-level radio frequency (LLRF) systems (< 5 MHz) at GSI. These applications require a high precision in amplitude and phase for the transmitted signals where a detailed knowledge of the line properties is of significant interest. As the corresponding data sheets do not provide appropriate data, the necessary data have been computed. The obtained results from the purely analytical model were then compared with previous measurements for validation purposes.
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WEPME065	European XFEL RF Gun Commissioning and LLRF Linac Installation	2427
	J. Branlard, G. Ayvazyan, V. Ayvazyan, Ł. Butkowski, M.K. Grecki, M. Hoffmann, F. Ludwig, U. Mavrič, S. Pfeiffer, H. Schlarb, Ch. Schmidt, H.C. Weddig, B.Y. Yang DESY, Hamburg, Germany S. Bou Habib, K. Czuba, M. Grzegrzółka, E. Janas, J. Piekarski, I. Rutkowski, R. Rybaniec, D. Sikora, L.Z. Zembala, M. Żukociński Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland W. Cichalewski, D.R. Makowski, A. Mielczarek, P. Perek, A. Piotrowski, T. Pożniak TUL-DMCS, Łódź, Poland S. Korolczuk, I.M. Kudla, J. Szewiński NCBJ, Świerk/Otwock, Poland K. Oliwa, W. Wierba IFJ-PAN, Kraków, Poland
	The European x-ray free electron laser (XFEL) is based on a 17.5 GeV super conducting pulsed linac and is scheduled to deliver its first beam in 2016. The first component of its accelerator chain, the RF gun, was installed in fall of 2013 and its commissioning is underway. This contribution gives an update on the low level radio frequency (LLRF) system development and installation for the XFEL. In particular, the installation, performance and conditioning results of the RF gun are presented. The subsequent steps toward LLRF components mass-production, testing and installation for the XFEL linac are also explained.
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WEPME066	High Speed Digitial LLRF Feedbacks for Normal Conducting Cavity Operation	2430
	M. Hoffmann, Ł. Butkowski, H. Schlarb, Ch. Schmidt DESY, Hamburg, Germany W. Köhler DESY Zeuthen, Zeuthen, Germany A. Piotrowski TUL-DMCS, Łódź, Poland I. Rutkowski, R. Rybaniec Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland
	In the first half of the year 2014, the MTCA.4 based LLRF control system will be installed at several facilities (FLASH RF Gun, REGAE, PITZ, FLUTE/KIT). First tests during the last year show promising results in optimizing the system for high speed digital llrf feedbacks (reducing system latency, increase internal controller processing speed). In this contribution we will present further improvements in latency and performance optimization of the system, results and gained experience from the commisioning of the system at the metioned facilities.
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WEPME067	Performance of the MTCA.4 Based LLRF System at FLASH	2433
	Ch. Schmidt, V. Ayvazyan, J. Branlard, Ł. Butkowski, M.K. Grecki, M. Hoffmann, F. Ludwig, U. Mavrič, K.P. Przygoda, H. Schlarb, H.C. Weddig, B.Y. Yang DESY, Hamburg, Germany W. Cichalewski, D.R. Makowski, A. Piotrowski TUL-DMCS, Łódź, Poland K. Czuba, I. Rutkowski, D. Sikora, M. Żukociński Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland I.M. Kudla NCBJ, Świerk/Otwock, Poland K. Oliwa, W. Wierba IFJ-PAN, Kraków, Poland
	The Free Electron Laser in Hamburg (FLASH) is the first linac which is equipped with a MTCA.4 based low level RF control system. Precise regulation of RF fields is essential for stable and and reproducible photon generation. Flash benefits from the performance increase using the new developments like, accurate and precise field detection devices. Further enourmous increase of processing capabilities allow for more sophisticated controller applications which better the overall performance of the regulation.
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WEPME068	Mitigating Noise Sources in MTCA.4 Electronics for High Precision Measurements	2436
	U. Mavrič, M. Hoffmann, F. Ludwig, H. Schlarb DESY, Hamburg, Germany
	The RF field detection instrumentation plays a crucial role in modern accelerator performance. The most critical section is the transition from the analog signal processing to the digitalization. In this paper we present state of the art performance of COTS components and limitations imposed by crate-oriented solutions. We give recipes on how to optimize performance and present some of the recent results.
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WEPME069	Performance of a Compact LLRF System using Analog RF Backplane in MTCA.4 Crates	2438
	U. Mavrič, M. Fenner, M. Hoffmann, F. Ludwig, A.T. Rosner, H. Schlarb DESY, Hamburg, Germany K. Czuba, T.P. Leśniak Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland A. Rohlev Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
	In order to increase system compactness, mitigate cabling problems, increase rack space, minimize points of failure in the system and reduce digital distortion leakage into the sensitive analog signals, the concept of the RF backplane located in the rear section of the MTCA.4 crate has been introduced. Besides signal distribution, the concept includes a signal generation module and backplane management module. The generation and splitting of the analog signals is taking place in slots 15 and 14 on the rear side in theμLO generation module (uLOG). This module generates the local oscillator signal, the clocks and feeds through the master reference signal over the RF backplane to the slots. In this paper we present the recent results of such system.
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WEPME070	Plans for the Implementation of an Intra-pulse Feedback on the Fermi Linac LLRF System	2441
	M. Milloch, A. Fabris, F. Gelmetti, M. Predonzani Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
	FERMI is a single-pass linac-based FEL user-facility covering the wavelength range from 100 nm (12 eV) to 4 nm (310 eV) and is located next to the third generation synchrotron radiation facility Elettra in Trieste, Italy. The 1.5 GeV S-band linac is composed of fifteen 3 GHz 45 MW peak RF power plants powering the gun, sixteen accelerating sections and the RF deflectors. The requirements on beam quality impose tight specifications on the stability of the electromagnetic fields that can be achieved only installing high reliable and high performance state of the art LLRF systems. While these requirements are presently met by the system installed, the on-going upgrade of the processing board with the final one will allow to add new functionalities of the system. One of the possible developments is the implementation of an intra-pulse feedback that will allow to apply the corrections inside the RF pulse. This paper provides an overview of the additional benefits that could be achieved and discusses the requirements and the constraints for the implementation in the machine.
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WEPME071	Development and Construction Status of New LLRF Control System for SuperKEKB	2444
	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 2015. A new LLRF control system, which is an FPGA-based digital RF feedback control system on the MicroTCA platform, has been developed to satisfy the requirement for high current beam operation of the SuperKEKB. Then final refinements were applied, and now the quantity production is in progress. As a new function, klystron phase lock loop was additionally implemented within the cavity feedback control loop in the FPGA, and it was successfully worked in the low-level operation test. For the SuperKEKB, damping ring (DR) is required for the positron injection. Therefore another new LLRF control system is under development for the DR-RF system. It is operated at the same RF-frequency as the main ring, and vector sum control of three cavities is needed in the DR-LLRF control. In this report, the development status and progress from the previous report will be presented including the RF reference distribution system.
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WEPME072	Performance of the Digital LLRF System at the cERL	2447
	F. Qiu, D.A. Arakawa, H. Katagiri, T. Matsumoto, S. Michizono, T. Miura KEK, Ibaraki, Japan
	A digital low-level radio frequency (LLRF) system has been developed and evaluated at compact Energy Recovery Linac (cERL) in High Energy Accelerator Research Organization (KEK), Japan. A total of three two-cell cavities were installed for the injector, and two nine-cell cavities were installed for the main linac. The required RF stabilities for these cavities are 0.1% rms in amplitude and 0.1° rms in phase. To satisfy these requirements, we survey feedback parameters such as the proportional and integral (PI) gains. Furthermore, we evaluated the beam energy fluctuation due to the vector-sum controlling error between the cavities injectors 2 and 3. Finally, we present the performance of the LLRF system that was realized in the beam commissioning. This paper describes the current status of the LLRF system.
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WEPME073	Performance of RF System for Compact-ERL Main Linac at KEK	2450
	T. Miura, M. Akemoto, A. Akiyama, D.A. Arakawa, S. Fukuda, H. Honma, H. Katagiri, T. Matsumoto, H. Matsushita, S. Michizono, H. Nakajima, K. Nakao, F. Qiu, H. Sakai, T. Shidara, T. Takenaka, K. Umemori, Y. Yano KEK, Ibaraki, Japan
	The construction of compact ERL in the first stage has been completed in the end of 2013. The rf commissioning in main-linac has been started. The main-linac consists of two nine-cell cavities. The loaded Q is high, ~10⁷. As the rf power sources, a solid state power amplifier and an inductive output tube (IOT) has been used for two cavities, respectively. The RF field and tuner have been successfully controlled by using micro-TCA digital feedback board. This paper reports about the RF commissioning and the performance.
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WEPME074	Development of Digital Low Level Radio Frequency Controller at SSRF	2453
	Y.B. Zhao, J.F. Liu, K. Xu, Zh.G. Zhang, S.J. Zhao, X. Zheng SINAP, Shanghai, People's Republic of China
	Digital low level radio frequency technology has been adopted in the storage ring of SSRF and a controller based on commercial FPGA and DSP board has been developed and operated successfully which helps SSRF to satisfy its specification with beam high to 300mA. The second generation controller has been fabricated in house and used with 240mA beam current at beginning of this year. The stability of amplitude and phase reaches 0.089% (RMS) and 0.093 degree (RMS) respectively. The recent progress on digital LLRF for FEL will be also reported such as the development activities and test results on the local oscillation generation board and down converter board.
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WEPME075	Real-time Estimation of Superconducting Cavities Parameters	2456
	R. Rybaniec Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland V. Ayvazyan, J. Branlard, Ł. Butkowski, S. Pfeiffer, H. Schlarb, Ch. Schmidt DESY, Hamburg, Germany W. Cichalewski, K.P. Przygoda TUL-DMCS, Łódź, Poland
	Performance of accelerators based on the superconductive cavities including FLASH and XFEL facilities at DESY is affected by cavity parameters variation over time. High gradient electromagnetic field inside cavities causes detuning due to the Lorentz force. In addition the quality factor of cavities can change during the RF field pulse. Currently used method for estimation of those parameters is based on the post-processing of the data recorded during operation of the RF. External servers calculate cavity parameters using cavity equation, forward power and probe signals collected during previous pulse. A novel approach* based on the component implemented in FPGA is presented. In the new method loaded quality factor and detuning are estimated in real-time during the RF pulse for increased reliability and better exception handling. Modified firmware of the LLRF control system based on the Micro Telecommunications Computing Architecture (MTCA) platform has been used for the method verification. *”Development of Control System for Fast Frequency Tuners of Superconducting Resonant Cavities for FLASH and XFEL Experiments”, K. Przygoda, PhD thesis, Technical University of Łódź, Poland, 2010.
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WEPME077	Advanced Automatic Frequency Control System for a Dual Energy S-band RF Electron Linear Accelerator	2459
SUSPSNE107	use link to see paper's listing under its alternate paper code
	S.S. Cha UST, Daejeon City, Republic of Korea Y. Kim ISU, Pocatello, Idaho, USA B.C. Lee, B.N. Lee, H.D. Park, K.B. Song KAERI, Daejon, Republic of Korea
	Funding: This work was supported by a National Research Foundation of Korea (NRF) grant funded by the ministry of science ICT & future Planning (No. 2010-0026088), and MOTIE Korea (13-DU-EE-12). The Radiation Instrumentation Research Division of Korea Atomic Energy Research Institute is developing a 2856 MHz dual energy [9, 6 MeV] s-band RF electron linear accelerator for security inspection. The s-band dual energy electron accelerator generates dual x-ray energy by irradiating a bunched electron beam from the cavity to a tungsten target. By detecting an x-ray, the cargo security inspection system can distinguish between organic and inorganic materials. Synchronization of the resonant frequency between the cavity and RF driver is an important factor for the stable operation of an accelerator. With a low RF driver power using the AFC, stable accelerator operations and a uniform output beam power can be obtained. This indicates that an accurate cargo inspection is possible. We used phase a frequency detector that can detect a wide frequency band and synchronize the resonance frequency between the RF driver and cavity. In this paper, we introduce a more advanced AFC system than a conventional AFC system.
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WEPME078	Experimental Test of the Prototype LLRF Systems for PAL-XFEL	2462
	J. Hu, H. Heo, J.H. Hong, W.H. Hwang, H.-S. Kang, H.-S. Lee, C.-K. Min PAL, Pohang, Kyungbuk, Republic of Korea
	Two prototype LLRF systems were developed in collaboration with Pohang Accelerator Laboratory(PAL) and domestic companies. They are focused on the control of single klystron system to obtain mainly analogue performance. The low power test of the developed LLRF showed good performance previously. We experimentally tested LLRF in the klystron systems to see performance in the high power situation. They showed performance around the prototype specification for short time and relatively long time. During test some bugs are discovered and fixed.
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WEPME079	LLRF System for the ESS Proton Accelerator	2465
	A.J. Johansson, F. Kristensen, A.M. Svensson Lund University, Lund, Sweden R. Zeng ESS, Lund, Sweden
	The European Spallation Source is driven by a proton linear accelerator that will have an average beam power of 5 MW. The accelerator is pulsed at 14 Hz with a pulse length of 2.86 ms, and consists of both normal conduction and superconducting accelerating structures. The long pulse and the high goals of energy efficiency and availability create special challenges for the LLRF system.
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Paper

Title

Page

A New Digital LLRF System for a Fast Ramping Storage Ring

2418

M. Schedler, F. Frommberger, W. Hillert, D. Proft, D. Sauerland
ELSA, Bonn, Germany
D. Teytelman
Dimtel, San Jose, USA

At the Electron Stretcher Facility ELSA of Bonn University, an upgrade 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 3.5 GeV and a slow extraction afterwards over a few seconds to the hadron physics experiments. The intended upgrade is mainly limited by the coupled-bunch instabilities and the ability of bunch-by-bunch feedback systems to suppress such instabilities. In order to achieve optimum bunch-by-bunch feedback performance, the beam phase with respect to the master oscillator and the synchrotron frequency have to stay constant. This paper reports on a new high performance low level RF (LLRF) system. The system stabilizes the cavity field and is capable of executing fast voltage and phase ramps. The LLRF uses FPGA-based digital signal processing and includes cavity tuner control as well as fast interlocks and extensive diagnostics.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPME062

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WEPME063

Pulsed Low Level Baseband RF Control of CH-Cavities for p-Linac at FAIR

2421

P. Nonn, U. Bonnes, C. Burandt, F. Hug, N. Pietralla
TU Darmstadt, Darmstadt, Germany
H. Klingbeil, G. Schreiber, W. Vinzenz
GSI, Darmstadt, Germany
H. Klingbeil
TEMF, TU Darmstadt, Darmstadt, Germany

Funding: This project was supported by the BMBF under grant No. 05P09RDRB5 and by the Helmholtz International Center for FAIR (HIC for FAIR) funded by the State of Hesse within its LOEWE initiative.
At the Facility for Antiproton and Ion Research (FAIR) in Darmstadt, Germany a high intensity antiproton beam will be produced. To provide the necessary 70 mA proton beam a dedicated proton linac (p-Linac) is under construction. The main acceleration will be provided by 9 novel CH-type cavities, of which 6 will be coupled in pairs to share the same klystron. To test the rf properties of these novel cavities, a test stand is under construction. An rf control system for the pulsed operation of these cavities has been developed at TU Darmstadt. It is based upon the digital cw rf control that is successfully in operation as part of the S-DALINAC at IKP Darmstadt. The latest developments will be presented.

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WEPME064

Comparison of an Analytical Model for Lossy Transmission Lines with Measurement Data

2424

SUSPSNE108

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

N. Schmitt
TEMF, TU Darmstadt, Darmstadt, Germany
H. Klingbeil
GSI, Darmstadt, Germany

This paper deals with the analytical modeling of lossy coaxial transmission lines in the frequency range from 100 kHz to 50 MHz with focus on corrugated coaxial lines with polyethylene foam as dielectric. The considered transmission lines are used in low-level radio frequency (LLRF) systems (< 5 MHz) at GSI. These applications require a high precision in amplitude and phase for the transmitted signals where a detailed knowledge of the line properties is of significant interest. As the corresponding data sheets do not provide appropriate data, the necessary data have been computed. The obtained results from the purely analytical model were then compared with previous measurements for validation purposes.

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WEPME065

European XFEL RF Gun Commissioning and LLRF Linac Installation

2427

J. Branlard, G. Ayvazyan, V. Ayvazyan, Ł. Butkowski, M.K. Grecki, M. Hoffmann, F. Ludwig, U. Mavrič, S. Pfeiffer, H. Schlarb, Ch. Schmidt, H.C. Weddig, B.Y. Yang
DESY, Hamburg, Germany
S. Bou Habib, K. Czuba, M. Grzegrzółka, E. Janas, J. Piekarski, I. Rutkowski, R. Rybaniec, D. Sikora, L.Z. Zembala, M. Żukociński
Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland
W. Cichalewski, D.R. Makowski, A. Mielczarek, P. Perek, A. Piotrowski, T. Pożniak
TUL-DMCS, Łódź, Poland
S. Korolczuk, I.M. Kudla, J. Szewiński
NCBJ, Świerk/Otwock, Poland
K. Oliwa, W. Wierba
IFJ-PAN, Kraków, Poland

The European x-ray free electron laser (XFEL) is based on a 17.5 GeV super conducting pulsed linac and is scheduled to deliver its first beam in 2016. The first component of its accelerator chain, the RF gun, was installed in fall of 2013 and its commissioning is underway. This contribution gives an update on the low level radio frequency (LLRF) system development and installation for the XFEL. In particular, the installation, performance and conditioning results of the RF gun are presented. The subsequent steps toward LLRF components mass-production, testing and installation for the XFEL linac are also explained.

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WEPME066

High Speed Digitial LLRF Feedbacks for Normal Conducting Cavity Operation

2430

M. Hoffmann, Ł. Butkowski, H. Schlarb, Ch. Schmidt
DESY, Hamburg, Germany
W. Köhler
DESY Zeuthen, Zeuthen, Germany
A. Piotrowski
TUL-DMCS, Łódź, Poland
I. Rutkowski, R. Rybaniec
Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland

In the first half of the year 2014, the MTCA.4 based LLRF control system will be installed at several facilities (FLASH RF Gun, REGAE, PITZ, FLUTE/KIT). First tests during the last year show promising results in optimizing the system for high speed digital llrf feedbacks (reducing system latency, increase internal controller processing speed). In this contribution we will present further improvements in latency and performance optimization of the system, results and gained experience from the commisioning of the system at the metioned facilities.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPME066

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WEPME067

Performance of the MTCA.4 Based LLRF System at FLASH

2433

Ch. Schmidt, V. Ayvazyan, J. Branlard, Ł. Butkowski, M.K. Grecki, M. Hoffmann, F. Ludwig, U. Mavrič, K.P. Przygoda, H. Schlarb, H.C. Weddig, B.Y. Yang
DESY, Hamburg, Germany
W. Cichalewski, D.R. Makowski, A. Piotrowski
TUL-DMCS, Łódź, Poland
K. Czuba, I. Rutkowski, D. Sikora, M. Żukociński
Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland
I.M. Kudla
NCBJ, Świerk/Otwock, Poland
K. Oliwa, W. Wierba
IFJ-PAN, Kraków, Poland

The Free Electron Laser in Hamburg (FLASH) is the first linac which is equipped with a MTCA.4 based low level RF control system. Precise regulation of RF fields is essential for stable and and reproducible photon generation. Flash benefits from the performance increase using the new developments like, accurate and precise field detection devices. Further enourmous increase of processing capabilities allow for more sophisticated controller applications which better the overall performance of the regulation.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPME067

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WEPME068

Mitigating Noise Sources in MTCA.4 Electronics for High Precision Measurements

2436

U. Mavrič, M. Hoffmann, F. Ludwig, H. Schlarb
DESY, Hamburg, Germany

The RF field detection instrumentation plays a crucial role in modern accelerator performance. The most critical section is the transition from the analog signal processing to the digitalization. In this paper we present state of the art performance of COTS components and limitations imposed by crate-oriented solutions. We give recipes on how to optimize performance and present some of the recent results.

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WEPME069

Performance of a Compact LLRF System using Analog RF Backplane in MTCA.4 Crates

2438

U. Mavrič, M. Fenner, M. Hoffmann, F. Ludwig, A.T. Rosner, H. Schlarb
DESY, Hamburg, Germany
K. Czuba, T.P. Leśniak
Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland
A. Rohlev
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy

In order to increase system compactness, mitigate cabling problems, increase rack space, minimize points of failure in the system and reduce digital distortion leakage into the sensitive analog signals, the concept of the RF backplane located in the rear section of the MTCA.4 crate has been introduced. Besides signal distribution, the concept includes a signal generation module and backplane management module. The generation and splitting of the analog signals is taking place in slots 15 and 14 on the rear side in theμLO generation module (uLOG). This module generates the local oscillator signal, the clocks and feeds through the master reference signal over the RF backplane to the slots. In this paper we present the recent results of such system.

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WEPME070

Plans for the Implementation of an Intra-pulse Feedback on the Fermi Linac LLRF System

2441

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

FERMI is a single-pass linac-based FEL user-facility covering the wavelength range from 100 nm (12 eV) to 4 nm (310 eV) and is located next to the third generation synchrotron radiation facility Elettra in Trieste, Italy. The 1.5 GeV S-band linac is composed of fifteen 3 GHz 45 MW peak RF power plants powering the gun, sixteen accelerating sections and the RF deflectors. The requirements on beam quality impose tight specifications on the stability of the electromagnetic fields that can be achieved only installing high reliable and high performance state of the art LLRF systems. While these requirements are presently met by the system installed, the on-going upgrade of the processing board with the final one will allow to add new functionalities of the system. One of the possible developments is the implementation of an intra-pulse feedback that will allow to apply the corrections inside the RF pulse. This paper provides an overview of the additional benefits that could be achieved and discusses the requirements and the constraints for the implementation in the machine.

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WEPME071

Development and Construction Status of New LLRF Control System for SuperKEKB

2444

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 2015. A new LLRF control system, which is an FPGA-based digital RF feedback control system on the MicroTCA platform, has been developed to satisfy the requirement for high current beam operation of the SuperKEKB. Then final refinements were applied, and now the quantity production is in progress. As a new function, klystron phase lock loop was additionally implemented within the cavity feedback control loop in the FPGA, and it was successfully worked in the low-level operation test. For the SuperKEKB, damping ring (DR) is required for the positron injection. Therefore another new LLRF control system is under development for the DR-RF system. It is operated at the same RF-frequency as the main ring, and vector sum control of three cavities is needed in the DR-LLRF control. In this report, the development status and progress from the previous report will be presented including the RF reference distribution system.

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WEPME072

Performance of the Digital LLRF System at the cERL

2447

F. Qiu, D.A. Arakawa, H. Katagiri, T. Matsumoto, S. Michizono, T. Miura
KEK, Ibaraki, Japan

A digital low-level radio frequency (LLRF) system has been developed and evaluated at compact Energy Recovery Linac (cERL) in High Energy Accelerator Research Organization (KEK), Japan. A total of three two-cell cavities were installed for the injector, and two nine-cell cavities were installed for the main linac. The required RF stabilities for these cavities are 0.1% rms in amplitude and 0.1° rms in phase. To satisfy these requirements, we survey feedback parameters such as the proportional and integral (PI) gains. Furthermore, we evaluated the beam energy fluctuation due to the vector-sum controlling error between the cavities injectors 2 and 3. Finally, we present the performance of the LLRF system that was realized in the beam commissioning. This paper describes the current status of the LLRF system.

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WEPME073

Performance of RF System for Compact-ERL Main Linac at KEK

2450

T. Miura, M. Akemoto, A. Akiyama, D.A. Arakawa, S. Fukuda, H. Honma, H. Katagiri, T. Matsumoto, H. Matsushita, S. Michizono, H. Nakajima, K. Nakao, F. Qiu, H. Sakai, T. Shidara, T. Takenaka, K. Umemori, Y. Yano
KEK, Ibaraki, Japan

The construction of compact ERL in the first stage has been completed in the end of 2013. The rf commissioning in main-linac has been started. The main-linac consists of two nine-cell cavities. The loaded Q is high, ~10⁷. As the rf power sources, a solid state power amplifier and an inductive output tube (IOT) has been used for two cavities, respectively. The RF field and tuner have been successfully controlled by using micro-TCA digital feedback board. This paper reports about the RF commissioning and the performance.

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WEPME074

Development of Digital Low Level Radio Frequency Controller at SSRF

2453

Y.B. Zhao, J.F. Liu, K. Xu, Zh.G. Zhang, S.J. Zhao, X. Zheng
SINAP, Shanghai, People's Republic of China

Digital low level radio frequency technology has been adopted in the storage ring of SSRF and a controller based on commercial FPGA and DSP board has been developed and operated successfully which helps SSRF to satisfy its specification with beam high to 300mA. The second generation controller has been fabricated in house and used with 240mA beam current at beginning of this year. The stability of amplitude and phase reaches 0.089% (RMS) and 0.093 degree (RMS) respectively. The recent progress on digital LLRF for FEL will be also reported such as the development activities and test results on the local oscillation generation board and down converter board.

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WEPME075

Real-time Estimation of Superconducting Cavities Parameters

2456

R. Rybaniec
Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland
V. Ayvazyan, J. Branlard, Ł. Butkowski, S. Pfeiffer, H. Schlarb, Ch. Schmidt
DESY, Hamburg, Germany
W. Cichalewski, K.P. Przygoda
TUL-DMCS, Łódź, Poland

Performance of accelerators based on the superconductive cavities including FLASH and XFEL facilities at DESY is affected by cavity parameters variation over time. High gradient electromagnetic field inside cavities causes detuning due to the Lorentz force. In addition the quality factor of cavities can change during the RF field pulse. Currently used method for estimation of those parameters is based on the post-processing of the data recorded during operation of the RF. External servers calculate cavity parameters using cavity equation, forward power and probe signals collected during previous pulse. A novel approach* based on the component implemented in FPGA is presented. In the new method loaded quality factor and detuning are estimated in real-time during the RF pulse for increased reliability and better exception handling. Modified firmware of the LLRF control system based on the Micro Telecommunications Computing Architecture (MTCA) platform has been used for the method verification.
*”Development of Control System for Fast Frequency Tuners of Superconducting Resonant Cavities for FLASH and XFEL Experiments”, K. Przygoda, PhD thesis, Technical University of Łódź, Poland, 2010.

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WEPME077

Advanced Automatic Frequency Control System for a Dual Energy S-band RF Electron Linear Accelerator

2459

SUSPSNE107

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S.S. Cha
UST, Daejeon City, Republic of Korea
Y. Kim
ISU, Pocatello, Idaho, USA
B.C. Lee, B.N. Lee, H.D. Park, K.B. Song
KAERI, Daejon, Republic of Korea

Funding: This work was supported by a National Research Foundation of Korea (NRF) grant funded by the ministry of science ICT & future Planning (No. 2010-0026088), and MOTIE Korea (13-DU-EE-12).
The Radiation Instrumentation Research Division of Korea Atomic Energy Research Institute is developing a 2856 MHz dual energy [9, 6 MeV] s-band RF electron linear accelerator for security inspection. The s-band dual energy electron accelerator generates dual x-ray energy by irradiating a bunched electron beam from the cavity to a tungsten target. By detecting an x-ray, the cargo security inspection system can distinguish between organic and inorganic materials. Synchronization of the resonant frequency between the cavity and RF driver is an important factor for the stable operation of an accelerator. With a low RF driver power using the AFC, stable accelerator operations and a uniform output beam power can be obtained. This indicates that an accurate cargo inspection is possible. We used phase a frequency detector that can detect a wide frequency band and synchronize the resonance frequency between the RF driver and cavity. In this paper, we introduce a more advanced AFC system than a conventional AFC system.

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WEPME078

Experimental Test of the Prototype LLRF Systems for PAL-XFEL

2462

J. Hu, H. Heo, J.H. Hong, W.H. Hwang, H.-S. Kang, H.-S. Lee, C.-K. Min
PAL, Pohang, Kyungbuk, Republic of Korea

Two prototype LLRF systems were developed in collaboration with Pohang Accelerator Laboratory(PAL) and domestic companies. They are focused on the control of single klystron system to obtain mainly analogue performance. The low power test of the developed LLRF showed good performance previously. We experimentally tested LLRF in the klystron systems to see performance in the high power situation. They showed performance around the prototype specification for short time and relatively long time. During test some bugs are discovered and fixed.

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WEPME079

LLRF System for the ESS Proton Accelerator

2465

A.J. Johansson, F. Kristensen, A.M. Svensson
Lund University, Lund, Sweden
R. Zeng
ESS, Lund, Sweden

The European Spallation Source is driven by a proton linear accelerator that will have an average beam power of 5 MW. The accelerator is pulsed at 14 Hz with a pulse length of 2.86 ms, and consists of both normal conduction and superconducting accelerating structures. The long pulse and the high goals of energy efficiency and availability create special challenges for the LLRF system.

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