MC6: Beam Instrumentation, Controls, Feedback and Operational Aspects
T27 Low Level RF
Paper Title Page
THYPLS1 RF Controls Towards Femtosecond and Attosecond Precision 3414
 
  • F. Ludwig, J. Branlard, Ł. Butkowski, M.K. Czwalinna, M. Hierholzer, M. Hoffmann, M. Killenberg, T. Lamb, J. Marjanovic, U. Mavrič, J.M. Müller, S. Pfeiffer, H. Schlarb, Ch. Schmidt, L. Springer
    DESY, Hamburg, Germany
  • M. Kuntzsch, K. Zenker
    HZDR, Dresden, Germany
 
  In the past two decades, RF controls have improved by two orders in magnitude achieving meanwhile sub-10 fs phase stabilities and 10-4 amplitude precision. Advances are through improved field detection methods and massive usage of digital signal procession on very powerful field programmable gate arrays (FPGAs). The question rise, what can be achieved in the next 10 years? In this talk, a review is given of existing systems and strategies, current stability limitations of RF control system and new technologies with the potential to achieve attosecond resolutions.  
slides icon Slides THYPLS1 [10.328 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THYPLS1  
About • paper received ※ 15 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
THYYPLS1 On-Demand Beam Route and RF Parameter Switching System for Time-Sharing of a Linac for X-ray Free-Electron Laser as an Injector to a 4th-Generation Synchrotron Radiation Source 3427
 
  • H. Maesaka, T. Fukui, T. Hara, T. Inagaki, H. Tanaka
    RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
  • T. Hasegawa, O. Morimoto, Y. Tajiri, S. Tanaka, M. Yoshioka
    SES, Hyogo-pref., Japan
  • N. Hosoda, S. Matsubara, T. Ohshima
    JASRI/SPring-8, Hyogo-ken, Japan
  • C. Kondo, K. Okada, M. Yamaga
    JASRI, Hyogo, Japan
 
  We have an upgrade plan of the SPring-8 storage ring to provide much more brilliant X-rays with a low-emittance electron beam. Since the upgraded ring requires a low-emittance injection beam, we are planning to timeshare the linac of the X-ray free electron laser (XFEL) facility, SACLA, as an injector for the upgraded ring. The SACLA linac delivers low-emittance and short-bunch electron beams to two XFEL beamlines with a 60 Hz repetition rate. The beam route is right now equally changed by a kicker magnet at a switchyard. The beam parameter is also optimized for each XFEL beamline by changing RF parameters pulse-by-pulse with simple software at this moment*. Since the number of beam injection shots to the storage ring is much less frequent than XFEL shots, one of the XFEL shots must be overridden by an injection with on-demand basis. In addition, the beam quality, such as 1 mm mrad normalized emittance, 10 fs bunch length and 10 kA peak current, must be maintained not to deteriorate the XFEL performance. Therefore, we have developed an on-demand beam route and RF parameter switching system with sufficient speed, precision and reliability. A beam route data is transmitted to each accelerator unit by a reflective memory network, and special software changes the parameters of each accelerator unit pulse-by-pulse according to the received data. We tested the on-demand switching system at a test bench and the SACLA linac. The beam parameters were appropriately controlled with a negligible failure rate. The user service of the beam injection from SACLA to SPring-8 is scheduled in 2020 and the on-demand switching system is almost ready for the time-sharing operation of multiple XFEL beamlines and a SPring-8 injection.
* T. Hara et al., Phys. Rev. Accel. Beams 21, 040701 (2018).
 
slides icon Slides THYYPLS1 [8.519 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THYYPLS1  
About • paper received ※ 16 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
THPRB007 Ponderomotive Instability of Self-Excited Cavity 3808
 
  • S.R. Koscielniak
    TRIUMF, Vancouver, Canada
 
  The electro-magnetic fields within a super-conducting radio frequency (SRF) cavity can be sufficiently strong to deform the cavity shape, which may lead to a ponderomotive instability. Stability criteria for the self-excited mode of cavity operation were given in 1978 by Delayen. The treatment was based on the Routh-Hurwitz analysis of the characteristic polynomial. With the Wolfram modern analytical tool, "Mathematica", we revisit the criteria for an SRF cavity equipped with amplitude and phase loops and a single microphonic mechanical mode.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB007  
About • paper received ※ 14 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
THPRB008 Ponderomotive Instability of Two Self-Excited Cavities 3812
 
  • S.R. Koscielniak
    TRIUMF, Vancouver, Canada
 
  We consider the ponderomotive instability of two superconducting RF cavities self-driven from a single RF source with vector-sum control.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB008  
About • paper received ※ 14 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
THPRB009 Vector Sum & Diffference Control of SRF Cavities 3816
 
  • S.R. Koscielniak
    TRIUMF, Vancouver, Canada
 
  We consider the ponderomotive instability of multiple superconducting RF cavities driven from a single RF source. We add vector difference control to the usual the technique of vector sum control, in order to increase the accelerating gradient threshold for ponderomotive instability.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB009  
About • paper received ※ 14 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
THPRB010 Ponderomotive Instability of Generator-Driven Cavity 3820
 
  • S.R. Koscielniak
    TRIUMF, Vancouver, Canada
 
  The electro-magnetic fields within a super-conducting radio frequency (SRF) cavity can be sufficiently strong to deform the cavity shape, which may lead to a ponderomotive instability. Stability criteria for the generator-driven mode of cavity operation were given in 1971 by Schulze. The treatment side-stepped the Routh-Hurwitz analysis of the characteristic polynomial. With the Wolfram modern analytical tool, ’Mathematica’, we revisit the criteria for an SRF cavity equipped with amplitude and phase loops and a single microphonic mechanical mode.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB010  
About • paper received ※ 14 May 2019       paper accepted ※ 18 May 2019       issue date ※ 21 June 2019  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
THPRB011 Norm-optimal Iterative Learning Control to Cancel Beam Loading Effect on the Accelerating Field 3824
SUSPFO005   use link to see paper's listing under its alternate paper code  
 
  • Z. Shahriari, K. Fong
    TRIUMF, Vancouver, Canada
  • G.A. Dumont
    UBC, Vancouver, Canada
 
  Iterative learning control (ILC) is an open loop control strategy that improves the performance of a repetitive system through learning from previous iterations. ILC can be used to compensate for a repetitive disturbance like the beam loading effect in resonators. In this work, we aim to use norm-optimal ILC to cancel beam loading effect. Norm-optimal ILC updates the control signal with the goal of minimizing a performance index, which results in monotonic convergence. Simulation results show that this controller improves beam loading compensation compared to a PI controller.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB011  
About • paper received ※ 14 May 2019       paper accepted ※ 19 May 2019       issue date ※ 21 June 2019  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
THPRB021 Automatic Loop for Carrier Suppression in Attosecond RF Receivers 3847
 
  • U. Mavrič, M. Hoffmann, F. Ludwig, H. Schlarb, L. Springer
    DESY, Hamburg, Germany
 
  The carrier suppression interferometer method can be used as a radio receiver architecture which allows for detection of RF signals in the attosecond range. The carrier suppression scheme requires an automatic carrier suppression circuit which provides stable operation of the RF receiver in the best operating point. In the poster we investigate the requirements for such an algorithm, evaluate the achievable closed loop bandwidth and the side effects on the overall-performance. In addition we apply the carrier tracking to simplify and automate the characterization of various electronic phase shifters and attenuators in the as-range  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB021  
About • paper received ※ 13 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
THPRB022 Sensitivity Analysis of Feedforward Beam Current Compensation for Improved Beam Loading Robustness 3850
 
  • D. Mihailescu Stoica, D. Domont-Yankulova
    RMR, TU Darmstadt, Darmstadt, Germany
  • D. Domont-Yankulova, H. Klingbeil
    TEMF, TU Darmstadt, Darmstadt, Germany
  • H. Klingbeil, D.E.M. Lens
    GSI, Darmstadt, Germany
 
  The planned SIS100 heavy ion synchrotron at the Facility for Antiproton and Ion Research (FAIR) in Darmstadt, Germany will possess twenty ferrite accelerating cavities in its final stage of extension. During the intended acceleration cycles, the cavities will encounter significant beam loading effects, which have to be handled by the control systems. As both the generator- and beam-current act on the same system input, a feedforward disturbance compensation can be a promising approach to improve beam qualities and suppress instabilities induced by the beam current. Particle tracking simulations, incorporating twenty ferrite cavities and their attached LLRF control systems, are performed to analyse the sensitivity of the beam quality with respect to errors in the feedforward beam current compensation. The main focus lies on the time after injection from a pre-accelerator, where most cavities in the SIS100 do not provide any gap voltage and thus are particularly sensitive to induced voltages by beam currents if the cavities are not or only partly short-circuited.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB022  
About • paper received ※ 10 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
THPRB024 Piezo Controls For The European XFEL 3856
 
  • K.P. Przygoda, J. Branlard, Ł. Butkowski, M.K. Grecki, M. Hierholzer, M. Omet, H. Schlarb
    DESY, Hamburg, Germany
 
  The European X-Ray Free Electron Laser (E-XFEL) accelerator is a pulse machine. The typical time duration of a radio frequency (RF) pulse is about 1.3 ms. The RF power transmitted to the superconducting RF (SCRF) cavity as a set of successive pulses (10 Hz repetition rate), causes strong mechanical stresses inside the cavity. The mechanical deformations of the RF cavity are typically caused by the Lorentz force detuning (LFD). The cavity can be tuned to a 1.3 GHz resonance frequency during the RF pulse using fast piezo tuners. Since the E-XFEL will use around 800 cavities (each cavity with double piezos), a distributed architecture with multi-channel digital and analog control circuits seems to be essential. The most sought-after issue is high-voltage, high-current piezo driving circuit dedicated to multi-channel configuration. The driving electronics should allow a maximum piezo protection against any kind of failure. The careful automation of the piezo tuners control and its demonstration for the high gradient conditions a real challenge. The first demonstration of piezo controls applied for chosen RF stations of the E-XFEL linear accelerator (linac) are presented and obtained results are briefly discussed within this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB024  
About • paper received ※ 30 April 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
THPRB025 New MicroTCA Piezo Driver (PZT4) 3860
 
  • K.P. Przygoda, Ł. Butkowski, M. Fenner, M. Hierholzer, R. Rybaniec, H. Schlarb, Ch. Schmidt
    DESY, Hamburg, Germany
  • R. Rybaniec
    PSI, Villigen PSI, Switzerland
 
  In the paper we would like to present a new Micro Telecommunication Computing Architecture (MicroTCA) piezo driver (PZT4). The piezo driver module is capable of driving of 4 piezo actuators with high voltages up to 160 Vpp. It is also possible to measure cavity mechanical vibrations using 4 analog to digital converters (ADC) ported to the driver electronics. The new piezo driver can be supplied using internal 12 V payload power provided by the MicroTCA standard. For the applications that need more than 30 W of the input power, the external power supply module can be provided. In order to protect the piezo driver electronics against output short condition a dedicated supervision circuit is designed. The piezo driver module has been setup at Cryo Module Test Bench (CMTB) facility in Deutsches-Elektronen Synchrotron (DESY) as a part of the single cavity low-level radio frequency (LLRF) controls. The LLRF control system has been used to demonstrate the radio frequency (RF) field stabilization and cavity tuning capabilities for continuous (CW) and pulse modes of operation of 1.3 GHz superconducting resonant RF (SCRF) cavity. The preliminary results are demonstrated and briefly discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB025  
About • paper received ※ 08 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
THPRB044 LLRF Control System for RF GUN at SXFEL Test Facility 3912
 
  • L. Li, Q. Gu, Y.J. Liu, C.C. Xiao, J.Q. Zhang
    SINAP, Shanghai, People’s Republic of China
  • Y.F. Liu, Z. Wang
    SARI-CAS, Pudong, Shanghai, People’s Republic of China
 
  A Soft X-ray Free Electron Laser Test Facility (SXFEL-TF) based on normal conducting linear accelerator was constructed at the Shanghai Synchrotron Radiation Facility (SSRF) campus by a joint team of Shanghai Institute of Applied Physics and Tsinghua University. It consists of multiple Radio Frequency (RF) stations with standing wave cavity (RF Gun) and traveling wave accelerating structures working at different frequencies. Low Level Radio Frequency (LLRF) system is used to measure the RF field in the cavities or structures and correct the fluctuation in RF fields with pulse-to-pulse feedback controllers. This paper describes the hardware and architecture of the LLRF system for electromagnetic filed stabilization inside the radio frequency electron gun, in the SXFEL-TF. A complete control path has be presented, including RF front-end board, I/Q detector and feedback controller. Algorithms used to stabilize the RF field have been presented as well as the software environment used to provide remote access to the control device. Finally, the performance of the LLRF system that was realized in the beam commissioning is presented and meets the high accuracy requirements.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB044  
About • paper received ※ 23 April 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
THPRB049 MODELING AND SIMULATION FOR MULTI-FEEDING CAVITY WITHOUT BEAM LOADING 3921
 
  • K. Liu, Q. Gu, L. Li, Ch. Wang, M.H. Zhao
    SINAP, Shanghai, People’s Republic of China
  • Q. Gu
    SSRF, Shanghai, People’s Republic of China
 
  The Multi-feeding cavity usually be applied in super-conducting and normal-conducting RF cavity. The differences between multiple input couplers in coupler coefficient, incident power and phase will cause the cavity field stabilities can not meet the requirements. For explore the influences of these differences and develop equations for measurement, a multi-feeding LCR transient model was developed. As two-feeding cavity, the VHF photocathode electron gun was model and simulated in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB049  
About • paper received ※ 06 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
THPRB050 LLRF System Modelling and Controller Design in UED 3924
 
  • Y.Q. Li, K. Fan, Y. Song
    HUST, Wuhan, People’s Republic of China
 
  In the Ultrafast Electron Diffraction (UED) facility for investigating material structure, drifts of amplitude and phase in cavity have different effects on beam quality. So it is critical for pump-probe experiments in the UED to keep accurate synchronization between the laser and electron. To achieve the desired 50fs resolution, the Low Level Radio Frequency (LLRF) controller in S-band normal conducting cavity needs to satisfy the stability: ±0.01% (rms) for the amplitude and ±0.01° (rms) for the phase, respectively. Then we can study the performance of the RF control system by simulating the LLRF system. In the simulation program, feedback, feed-forward algorithms, and beam current variations can be simulated in a Matlab/Simulink environment. This paper shows that a model-based controller design can meet the necessary requirements of the field regulation and implement the algorithms.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB050  
About • paper received ※ 20 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
THPRB063 Field Control Challenges for Different LINAC Types 3946
SUSPFO095   use link to see paper's listing under its alternate paper code  
 
  • O. Troeng, A.J. Johansson
    Lund University, Lund, Sweden
  • M. Eshraqi
    ESS, Lund, Sweden
  • S. Pfeiffer
    DESY, Hamburg, Germany
 
  Linacs for free-electron lasers typically require cavity field stabilities of 0.01\% and 0.01 degree, while the requirements for high-intensity proton linacs are on the order of 0.1–1\% and 0.1–1 degrees. From these numbers it is easy to believe that the field control problem for proton linacs is many times easier than for free-electron lasers linacs. In this contribution we explain why this is not necessarily the case, and discuss the factors that make field control challenging. We also discuss the drivers for field stability, and how high-level decisions on the linac design affect the difficulty of the field control problem.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB063  
About • paper received ※ 15 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
THPRB066 Beam Based Measurements of Relative RF Phase 3950
 
  • S.C.P. Albright
    CERN, Geneva, Switzerland
  • M.D. Kuczynski
    LPCT, Vandoeuvre-lès-Nancy Cedex, France
 
  The ferrite loaded RF cavities of the CERN Proton Synchrotron Booster will be replaced with FinemetTM loaded cavities during Long Shutdown 2 2019-2020). To fully realise the potential of the new cavities, the relative RF phases must be aligned along the acceleration ramp, where the revolution frequency changes by nearly a factor of 2. A beam based method of measuring the relative phase between the cavities is desired to give the best possible compensation for the frequency dependent phase shift. In this paper we present an operationally viable method to measure the phase shift as a function of RF frequency. The relative phase of the RF cavities can be aligned to within a few degrees, giving an error on the voltage seen by the beam of less than 1%.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB066  
About • paper received ※ 08 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
THPRB067 Time Varying RF Phase Noise for Longitudinal Emittance Blow-Up 3954
 
  • S.C.P. Albright
    CERN, Geneva, Switzerland
  • D. Quartullo
    Sapienza University of Rome, Rome, Italy
 
  RF phase noise was shown to be effective for controlled longitudinal emittance blow-up in the Proton Synchrotron Booster (PSB) at CERN during beam tests in 2017, with further developments in 2018. At CERN, RF phase noise is used operationally in the Super Proton Synchrotron (SPS) and Large Hadron Collider (LHC). In this paper we show that it is suitable for operation with a variety of beam types in the PSB. In the PSB the synchrotron frequency changes by approximately a factor 4 during the 500 ms acceleration ramp, requiring large changes in the frequency band of the noise. During 2018, a new method of calculating the noise parameters has been demonstrated, which gives upper and lower bounds to the noise frequency band that are smoothly varying through the ramp. The new calculation method has been applied to operational beams accelerated in both single and double RF harmonics, the final results are presented here.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB067  
About • paper received ※ 29 April 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
THPRB068 Upgrade of CERN’s PSB Digital Low-Level RF System 3958
 
  • M.E. Angoletta, S.C.P. Albright, A. Findlay, M. Jaussi, J.C. Molendijk, N. Pittet
    CERN, Geneva, Switzerland
 
  The CERN PS Booster (PSB) is the first circular accelerator in the LHC proton injector chain. The upgrade of this four-ring machine is underway within the framework of the LHC Injectors Upgrade project. The existing digital Low-Level RF (LLRF) system will also be upgraded. This paper outlines the LLRF capabilities required, their implementation and the challenges involved. Results of tests carried out to prepare for the LLRF upgrade are given.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB068  
About • paper received ※ 13 May 2019       paper accepted ※ 18 May 2019       issue date ※ 21 June 2019  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
THPRB069 The New Digital Low-Level RF System for CERN’s Extra Low Energy Antiproton Machine 3962
 
  • M.E. Angoletta, M. Jaussi, J.C. Molendijk
    CERN, Geneva, Switzerland
 
  CERN’s new Extra Low ENergy Antiproton accelerator/decelerator (ELENA) completed its initial commissioning in 2018. This machine is equipped with a new digital Low-Level RF (LLRF) system that implements beam and cavity loops as well as longitudinal diagnostics. ELENA’s LLRF was instrumental for machine commissioning by decelerating some 1 E7 antiprotons from 5.3 MeV to 100 keV. Commissioning with H ions took also place. Challenges faced included coping with low beam intensity and the wide frequency swing. This paper gives an overview of the LLRF system capabilities and operation. Beam results achieved with both H ions and antiprotons are also shown.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB069  
About • paper received ※ 13 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
THPRB070 A New Digital Low-Level RF and Longitudinal Diagnostic System for CERN’s AD 3966
 
  • M.E. Angoletta, S.C.P. Albright, A. Findlay, M. Jaussi, J.C. Molendijk, V. R. Myklebust
    CERN, Geneva, Switzerland
 
  The Antiproton Decelerator (AD) has been routinely providing 3 E7 antiprotons since July 2000 at 100 MeV/c from 3.5 GeV/c. It will be refurbished during the Long Shutdown 2 (LS2) to provide reliable operation for the new Extra Low ENergy Antiproton (ELENA) ring. AD will be equipped with a new digital Low-Level RF (LLRF) system before its restart in 2021. Diagnostics to measure beam intensity, Δp/p and Schottky spectra will also be developed. This paper is an overview of the planned capabilities and implementations, as well as of the challenges to overcome.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB070  
About • paper received ※ 13 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
THPRB082 The CERN SPS Low Level RF upgrade Project 4005
 
  • G. Hagmann, P. Baudrenghien, J.D. Betz, J. Egli, G. Kotzian, M. Rizzi, L. Schmid, A. Spierer, T. Włostowski
    CERN, Meyrin, Switzerland
  • F.J. Galindo Guarch
    Universitat Politécnica de Catalunya, Barcelona, Spain
 
  The High Luminosity LHC project (HL-LHC) calls for the doubling of the beam intensity injected from the Super Proton Synchrotron (SPS). This is not possible with the present RF system consisting of four 200 MHz cavities. An upgrade was therefore launched, consisting of the installation of two more cavities during the machine shutdown in 2019-2020 (LS2). Installation of more cavities requires the installation of extra Low Level RF (LLRF) electronics. The present LLRF system consists of the original equipment installed in the 1970s, plus some additions dating from the late 1990s when the SPS was commissioned as LHC injector. The High-Power RF up-grade has motivated a complete renovation of the LLRF during LS2; use of a MicroTCA platform, use of a digital deterministic link for synchronization (the so-called White Rabbit), use of an absolute clock for the processing, new algorithms for reducing the cavity impedance, and a complete re-design of the beam control loops and slip-stacking.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB082  
About • paper received ※ 13 May 2019       paper accepted ※ 19 May 2019       issue date ※ 21 June 2019  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
THPRB094 Study of the System Stability for the Digital Low Level RF System Operated at High Beam Currents 4042
 
  • Z.K. Liu, F.Y. Chang, L.-H. Chang, M.H. Chang, S.W. Chang, L.J. Chen, F.-T. Chung, Y.T. Li, M.-C. Lin, C.H. Lo, Ch. Wang, M.-S. Yeh, T.-C. Yu
    NSRRC, Hsinchu, Taiwan
 
  The purpose of a Low-Level Radio Frequency (LLRF) system is to control the amplitude and phase of the field in the accelerating cavity. A digital LLRF (DLLRF) system will be installed in the Taiwan Photon Source (TPS) storage ring in 2019. The system stability depends much on the feedback parameters. An instability of the cavity voltage controlled by a DLLRF was observed during machine tests with high beam current and low feedback gain. A simulation model for the digital LLRF system with beam-cavity interaction was developed to investigate this instability and simulations and machine test results will be presented here.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB094  
About • paper received ※ 07 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
THPRB097 Analysis of RF System Stability on CLARA 4053
 
  • N.Y. Joshi, J.K. Jones, A.J. Moss, E.W. Snedden, A.E. Wheelhouse
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • A.C. Dexter, J. Henderson
    Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
  • J.K. Jones
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
 
  The Compact Linear Accelerator for Research and Applications (CLARA) facility at STFC Daresbury Laboratory will test underpinning concepts and technology for a next generation X-ray free electron laser (FEL). CLARA will use four S-band normal conducting traveling wave linacs to accelerate electron bunches to a maximum energy of 250 MeV. The amplitude and phase stability of the collected RF systems is critical in enabling CLARA to achieve low (10 fs) shot-to-shot timing jitter of the photon output. Here we present initial measurements and model of the amplitude and phase jitter of the CLARA RF systems, achieved by experimentally correlating the klystron output with controls from modulator, driver, and other environment parameters. The effect of the RF jitter on the CLARA beam momentum is also integrated in the model.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB097  
About • paper received ※ 10 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
THPTS022 The Realization of Iterative Learning Control for J-PARC LINAC LLRF Control System 4155
 
  • S. Li
    J-PARC, KEK & JAEA, Ibaraki-ken, Japan
  • Z. Fang, Y. Fukui, K. Futatsukawa, F. Qiu
    KEK, Ibaraki, Japan
  • Y. Sato, S. Shinozaki
    JAEA/J-PARC, Tokai-mura, Japan
 
  The beam current of j-parc linac was planned to increase to 60 mA. The stronger beam current will lead to higher beam loading effect. Due to the low Q factor of cavity in high β section of linac, the traditional PID feedback & feedforward control method may have to face huge challenges. In order to make the system run better at 60 mA, the iterative learning control (ILC) method was put forward to use in LLRF control system. All the ILC operations are done in EPICS-PC. By installing the PyEpics module, we can use python programs to realize the data interaction between EPICS system and PC and further realize the ILC algorithm. In this paper, the architecture of ILC methods will be introduced. The performance of ILC method will be reported.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS022  
About • paper received ※ 15 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
THPTS060 Sirius Digital LLRF 4244
 
  • A. Salom, F. Pérez
    ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
  • R.H.A. Farias, F.K.G. Hoshino, A.P.B. Lima
    LNLS, Campinas, Brazil
 
  Sirius is a Synchrotron Light Source Facility based on a 4th generation low emittance storage ring. The facility is presently under construction in Campinas, Brazil, and comprises a 3 GeV electron storage ring, a full energy booster synchrotron and a 120 MeV linac. The booster RF system is based on a single 5-cell cavity driven by a 50 kW amplifier at 500MHz and is designed to operate at 2 Hz rate. The storage ring RF system will start with 1 normal conducting 7-cell cavity. In the final configuration, the system will comprise 2 superconducting cavities, each one driven by a 240 kW RF amplifier. A digital LLRF system based on ALBA LLRF has been designed and commissioned to control 3 different types of cavities: 2 normal conducting single cell cavities, one multi-cell cavity driven by 2 amplifiers and one superconducting cavity driven by 4 amplifiers. The first LLRF System was installed and commissioned in the Sirius Booster in 2019. The performance of the control loops with beam, together with other utilities of the system like automatic start-up, conditioning, fast interlocks and post-mortem analysis will be presented in this paper, as well as possible upgrades for the future  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS060  
About • paper received ※ 15 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
THPTS075 Performance Tests of a Digital Low-Level Rf-System at the TPS 4292
 
  • F.Y. Chang, L.-H. Chang, M.H. Chang, S.W. Chang, L.J. Chen, F.-T. Chung, Y.T. Li, M.-C. Lin, Z.K. Liu, C.H. Lo, Ch. Wang, M.-S. Yeh, T.-C. Yu
    NSRRC, Hsinchu, Taiwan
 
  A digital low-level RF (DLLRF) control system for the cavity gap voltage is now common throughout the world. At the Taiwan Photon Source (TPS) we installed and operated a DLLRF in the booster ring in 2018 successfully and plan to install it also in the storage ring in 2019. Operational and beam loading tests of the DLLRF at the storage ring are ongoing. The performance of the DLLRF in the presence of a large number of 60 Hz harmonics and its stability for gap voltage and phase will be discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS075  
About • paper received ※ 10 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)