LLRF 2011

17 Oct 2011, 09:00 → 20 Oct 2011, 16:50 Europe/Berlin

Auditorium (DESY)

Sophisticated Low-Level RF systems are essential to control RF structures and their power sources in modern particle accelerators for producing high-quality beams. The goals of the LLRF workshop are to share our experiences, to present the status of our work, and to discuss recent developments and future prospects in this field. For further information please visit http://llrf2011.desy.de

Monday, 17 October

Session 1

Convener: Dr Mariusz Grecki (DESY)

1 Accelerator Activities at DESY

Welcome talk

Speaker: Dr Reinhard Brinkmann (DESY)

2 LLRF: A History

Low level Radio Frequency (LLRF) control systems have been used for a long time and while their purpose has not changed greatly over time their architecture has. This paper will highlight the history of RF systems from the past looking toward the future, covering the initial systems where controls have been extremely crude to the modern digital controls systems used to maintain the tight amplitude and phase requirements needed in today’s systems. This is planned to be presented as an entertaining talk showing some of the highlights of the LLRF history.

Speaker: Mr Mark Crofford (Oak Ridge National Laboratory)

Slides LLRF_-_A_History.ppt

3 DESY Laboratory Talk

Speaker: Holger Schlarb (DESY)

movie bbf3.avi

Slides LLRF2011_WS_Schlarb_v1.ppt

11:20 Coffee break

Session 2

Convener: Alexander Gamp (DESY)

4 KEK LLRF Systems

The status of LLRF systems at KEK accelerators will be reported, including the J-PARC, KEKB, STF, and ERL. The recent progress in the past two years will be presented, and the future plan will also be discussed.

Speaker: Dr Zhigao Fang (KEK)

Slides LLRF_2011_Fang_2011_10_17_KEK_Lab_Talk.ppt

5 LLRF system performance at S1-Global in KEK

In S1-Global on 2010 and 2011, we have tested total 8 SC cavities (2 cav. from DESY, 2 from FNAL and 4 from KEK) aiming for ILC. The digital FB system using cPCI or uTCA are adopted for vector-sum field regulation. The RF stabilities of 0.007% in amplitude and 17 mdeg. in phase were obtained. Various diagnostics such as on-line quench pulse detector, dynamic detuning monitor were also implemented. The detail of the performance of LLRF system in S1-Global will be reported.

Speaker: Takako Miura (KEK)

Slides LLRF_S1-Global_miura.pdf

6 Jefferson Lab Laboratory talk

Slides LLRF_2011_JLAB_Talk.pptx

7 Cornell Laboratory Talk

Speaker: Dr Vivian Ka Mun HO (Cornell)

Slides LLRF_talk_-_Vivian_Ho_Cornell_University.pdf

13:00 Lunch

Session 3

Convener: Mr Mark Crofford (Oak Ridge National Laboratory)

8 Overview of CERN LLRF activities 2010-2011

CERN LLRF activities of the past two years are reviewed. This includes the first two years of LHC Physics running and in particular how the LLRF systems in the injector chain have contributed to the steep luminosity increase in LHC. Major upgrade projects for the future are also reviewed, along with new activities that started in the area of control of super-conducting RF cavities.

Speaker: Dr Wolfgang HOEFLE (CERN)

Slides WH_Lab_Talk_LLRF_2011.ppt

9 The LHC RF: Experience with Beam Operation

The LHC commissioning with beam and the first two years of physics operation, 2010 and 2011 as seen by the RF system are presented with particular emphasis on the encountered problems and solutions. It became clear in early 2010 that RF noise was well under control: the crossing of the much feared 50 Hz line for the synchrotron frequency did not affect the beam. The LHC RF noise is reduced to a level that makes its contribution to beam diffusion in physics well below that of Intra Beam Scattering. Capture losses are also under control, at well below 0.5 %. Longitudinal emittance blow-up, needed for stability, was rapidly commissioned. In 2011, 3.5 TeV/beam physics has been done with above 1380 bunches at 50 ns spacing, corresponding to 55% nominal current. The intensity per bunch (1.3E11 p) is significantly above the nominal 1.15E11. By August 2011 the LHC has accumulated more than 2 fb-1 integrated luminosity well in excess of the 1 fb-1 target for 2011.

Speaker: Dr Baudrenghien Philippe (CERN)

Slides LHCRFv2.pptx

10 Fermilab Laboratory Talk

Speaker: Mr Brian Chase (FNAL)

Slides fermi_lab_talk_chase2.pptx.pdf

16:00 Hamburg visit

18:10 Welcome Reception

Tuesday, 18 October

Session 4

Convener: Mr Larry Doolittle

11 Control System Fundamentals

Speaker: Tomasz Plawski

Slides llrf11_plawski10.pptx

12 LLRF SYSTEM REQUIREMENTS FOR SRF DRIVEN NEXT GENERATION LIGHT SOURCES

Abstract A number of next generation light sources have been proposed which make use of superconducting radio frequency (SRF) cavities as the primary accelerating elements. The cavities are used in injectors, standard linac configurations and energy recovered linac configurations. We will describe the general requirements for the low level RF systems used in next generation light sources which are driven by SRF linacs. The talk will describe the general schemes used for each of these types of machines. It will describe the general requirements for the LLRF systems for operations as well as for commissioning the cavities once they are installed in the accelerator. Operational issues and challenges will also be discussed. Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. The U.S. Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce this manuscript for U.S. Government purposes. # powers@jlab.org

Speaker: Mr Tom Powers (Jefferson Lab)

Slides LLRF_systems_for_next_generation_light_sources_v2.pptx

13 A Review of Fast and Slow Tuners for Superconducting Cavities

SRF cavities required slow tuner to statically tune cavities after cool down. To compensate for dynamic detuning SRF cavities equipped with fast tuner. Review of varieties of slow/fast tuners developed for SRF cavities at different laboratories will be presented.

Speaker: Dr Yuriy Pischalnikov (FNAL)

Slides LLRF2011-Tuners-Review-final.pptx

14 Active Disturbance Rejection Control of Superconducting Cavities

In the past few years, the NSCL has tested several techniques to reduce the effects of microphonics on superconducting cavities. One of these techniques is to replace the standard RF PID control with an ADRC (active disturbance rejection control). This type of controller uses a state observer to estimate the portion of the cavity feedback caused by disturbances. The control is then split into two parts, and the disturbances are directly cancelled using the RF drive, allowing higher gain to be used to control the cavity. The performance of the LLRF controller showed significant improvement when using ADRC compared to the PID controller. This talk will show the control statistics for both types of control used at NSCL. The talk will also cover some implementation challenges in implementing ADRC on the NSCL LLRF systems.

Speaker: Nathan Usher (National Superconducting Cyclotron Laboratory)

Slides LLRF-2011_Usher.pdf

15 ADAPTIVE COMPENSATION FOR LORENTZ FORCE DETUNING IN SUPERCONDUCTING RF CAVITIES

The Lorentz force can dynamically detune pulsed Superconducting RF cavities. Considerable additional RF power can be required to maintain the accelerating gradient if no effort is made to compensate for this detuning. An adaptive feed-forward Lorentz Force Detuning (LFD) compensation algorithm developed at Fermilab is described. Systems based on this approach have been used to successfully reduce LFD from several hundred Hz to several 10s of Hz or better.

Speaker: Warren Schappert (Fermilab)

movie Adaptive_LFD_Compensation.avi

Slides LLRF2011_Adaptive_lfd.pptx

11:10 Coffee break

Session 5

Convener: Dr Alexander Schnase (JAEA J-PARC Center)

16 Precision regulation of radio frequency fields at FLASH

Highly precise regulation of accelerator RF fields is a prerequisite for a stable and reproducible photon generation at Free Electron Lasers such as FLASH. Due to major improvements of the RF field controls during 2010 and 2011 the FEL performance and the beam stability was significantly improved. This includes beside achieved RF field stabilities in amplitude below the 0.01% (rms) level and in phase below 0.01 (rms) degrees, a higher reproducibility and degree of automation. The cascaded control loop concept will be presented as well as an outlook for further improvements in the regulation and automation strategy.

Speaker: Dr Christian Schmidt (DESY)

Slides 1_prec_reg_LLRF_workshop2011.pptx

17 LLRF Firmware of Fermi@Elettra

FERMI@Elettra is the soft X-ray, fourth generation light source facility at the Elettra Laboratory in Trieste, Italy. It is based on a seeded FEL, driven by a normal conducting linac that is presently expected to operate up to 1.5 GeV. To meet the requirements on phase and amplitude stabilitiy of the RF fields, state of the art technology must be adopted for the LLRF of the machine. The LLRF system is developed in the frame of a collaboration agreement between Sincrotrone Trieste and Lawrence Berkeley National Lab. This paper describes the LLRF firmware developed for Fermi to achieve those constraints. The main characteristics of this firmware are: non-IQ demodulation of the IF inputs, CIC filtering, amplitude and phase loops, PLL loop, calibration cables loop, reference phase drift compensation, phase modulation for Sled operation, Ethernet communications and diagnostics of the system. Further developments are still foreseen like intrapulse feedback, iterative learning and real time Ethernet communications between different LLRF systems to implement a global feedback system. This firmware has been integrated in two different hardware platforms based on FPGAs, fast ADCs and DACs: the LLRF4 Board (Spartan-3 FPGA and USB communications) and the FERMI AD Board (Virtex-5 FPGA Ethernet communications). The former board was installed to provide an “intermediate system” for the machine to perform the basic functionalities, while the latter has been specifically developed to attain the ultimate performances.

Speaker: Mr Larry Doolittle (Lawrence Berkeley National Laboratory)

Slides 2fermi_firmware.pdf

18 LHC Matlab Tools and 1-turn Feedback commissioning

Following the PEP-II experience, Matlab based tools have been used at the LHC for multiple configuration, machine development, and diagnostic purposes. These include the remote setting and optimization of the cavity controller, monitoring of beam, RF, and LLRF parameters, as well as synchronous excitations and acquisitions of system parameters. A synopsis of these applications is presented, with an emphasis on the 1-turn feedback implementation. The 1-turn feedback is an FPGA based feedback system part of the LHC cavity controller, which produces gain only around the revolution frequency harmonics. As such, it helps reduce the transient beam loading and effective cavity impedance. Consequently, it increases the stability margin for Longitudinal Coupled Bunch Instabilities driven by the cavity impedance at the fundamental and allows reliable operation at higher beam currents. The 1-turn feedback commissioning tools and the resulting performance improvements are presented.

Speaker: Dr Themistoklis Mastoridis (CERN)

Slides Mastoridis_2.pdf

19 Feedback Strategies for longitudinal Beam Stabilization

Stabilization of the bunch arrival time and compression is the main goal for the LLRF control system, which can be optimized by using beam information in additional feedback loops. Therefore a beam based feedback strategy is presented, distributing the control into three different time domains.    First a fast intra-train feedback loop acting on a us level during the macro-pulse reducing the arrival-time and compression jitter. This is further supported by a pulse to pulse feedback which minimizes residual control errors from the fast feedback by changes of the set-point trajectory. Finally a slow feedback loop acting in ranges of 1-10s, compensating slow drifts in the machine by modifying the set-point values. Measurement results will be presented to discuss advantages of different methods. Finally the combination of beam and field feedbacks will be given.

Speaker: Mr Sven Pfeiffer (DESY)

Slides SP_LLRF_2011_BBF_strategies.pdf

20 RF Gun Operation with Alternating RF Pulse Structure (Pulses inside the Pulse Mode)

V. Ayvazyan, B.Faatz, K. Floettmann, O.Hensler, W.Jalmuzna, D. Lipka, P. Morozov, H. Schlarb, S. Schreiber, V.Vogel The Free-Electron Laser in Hamburg (FLASH) is a user facility since 2005, delivering femtosecond short radiation pulses in the wavelength range between 4.1 and 44 nm using the SASE principle. In FLASH, the electron beam is accelerated to 1.25 GeV with L-band superconducting cavities. The electron source is a normal conducting RF-gun photoinjector. The L-band standing wave RF gun has one and a half cells. The gun is operated in burst mode with an RF pulse length of up to 900 microseconds and a repetition rate of 10 Hz. Several hundreds to thousands of bunches are accelerated per second. With 5 MW of pulsed forward power, the dissipated power inside the RF gun is 45 kW. We are proposing an operational mode which allows us to reduce the dissipated power to ease operation or to increase the effective duty cycle in the gun by pulsing the gun within one burst. We report on first experimental results at FLASH.

Speaker: Dr Vladimir Vogel (DESY)

Slides Flash_pip_LLWS.pdf

21 Q&A

13:20 Lunch break

Session 6

Convener: Mr Brian Chase (FNAL)

22 Receiver Fundamentals

Speaker: Dr Frank Ludwig (DESY)

Slides LLRF11_Receiver_Fundamentals_18_10_11_FLudwig_P1_final.pdf

23 Prototype Performance of Digital LLRF Control System for the SuperKEKB

SuperKEKB is a new project to upgrade the luminosity to 40 times higher than that of the KEKB accelerator. In order to obtain this high luminosity, the nano-beam scheme will be adopted at the interaction point, accordingly, low-emittance beam will be required. Furthermore, the stored beam current should be approximately twice as high as the KEKB. Therefore, for the high-current and high-quality beam acceleration without instability, accuracy and flexibility in accelerating field control are very significant. For the SuperKEKB project, a new LLRF control system has been developed to realize high accuracy and flexibility. It is an FPGA-based digital RF feedback control system using 16-bit ADC's, which works on the µTCA platform. In this µTCA-module, the Linux-OS runs then it performs as the EPICS-IOC. This LLRF system is available to both of normal-conducting cavity and super-conducting cavity. A prototype of the LLRF control system for the SuperKEKB was produced. Its basic performance of the RF control was evaluated by using a simulant cavity. The evaluation results and future issue for the operation will be presented in this report. The amplitude and phase stability in the feedback control is 0.03% and 0.02 degrees, respectively. It is sufficiently stable for the SuperKEKB.

Speaker: Dr Tetsuya Kobayashi (KEK)

Slides Kobayashi_SuperKEKB-LLRF.pdf

24 An Extended Baseband Network Analyzer Embedded in the Digital LLRF

The embedded baseband network analyzer in digital LLRF systems has been around for over 10 years as developed at SLAC for PEP-II. These systems allow creation of very efficient tools to configure and verify the loop settings in LLRF systems, even in closed loop. They operate by injecting a burst of baseband noise into the digital section of the regulation loop while acquiring the loop reactions at a selected point in the loop. The resulting transfer function is fitted to a model to extract descriptive parameters of the system. When precise measurements are required further away from the central RF carrier the precision of this basic method is limited by the available length of the excitation and acquisition buffers. The extended baseband network analyzer architecture overcomes these problems by means of a digital up-modulation of the baseband noise and a subsequent digital down-modulation prior to the acquisition recording. The injected noise file contains as before only narrow band, low frequency noise, but it is now transposed to the desired frequency offset by a digital modulator. On the acquisition side a similar (de)modulator is used to transpose the measured signal back down to baseband prior to a low-pass filter stage and the data recorder. By performing successive measurements at different frequency offsets a wideband response can be evaluated through a succession of narrowband measurements with greater precision over the entire loop bandwidth. Such an architecture has been implemented in the FPGA of the LHC 1-turn feedback and has demonstrated the possibility to precisely measure the narrow 58 Hz notches of the 1-turn feedback comb filter response more than 1 MHz away from the carrier, well beyond the LHC cavity controller 3dB bandwidth.

Speaker: Mr John Molendijk (CERN)

Slides An_Extended_Base-band_Network_Analyzer_Embedded_in_the_Digital_LLRF.ppt

25 System Architecture and Hardware Development for the LLRF System for EU-XFEL using MTCA.4

The Low-Level RF (LLRF) control system for EU-XFEL in each RF station requiers simultaneous data acquisition of up to 100 fast ADC channels at sampling rates of around 100 MHz and real time signal processing within a few hundred nanoseconds. At the same time the standardization of all systems are common objectives for DESY for cost reduction, performance optimization and machine reliability. A new MTCA.4 specification is an extention of the telco MTCA basic specifications. MTCA.4 defines analog IOs, Rear Transition Modules, high speed serial communication, precision clock and trigger distribution, and full management based od IPMI. A architecture of the LLRF system based on MTCA.4 allows for modular designs with highly integrated backplane interfaces and custom RF signal distribution. Presentation will cover boards development at DESY and presents the LLRF system architecture.

Speaker: Dr Tomasz Jezynski (DESY)

Slides tjezynski_LLRF_18.10.2011.pdf

16:20 Coffee break

Session 7

Convener: Dr Dmitry Teytelman (Dimtel, Inc.)

26 Upgrade of the RF Reference System at J-PARC LINAC

In J-PARC, the accelerator systems are controlled using the master clock of 12 MHz made in Computer/Network Equipment Room (CER) of the central control building. The low-level radio frequency (LLRF) system of LINAC is based on the reference signal of 312 MHz synchronized with the 12 MHz clock. The reference signal was made by a module, which is called “RF&CLK board”, in the upstream part of Klystron Gallery and then the reference signal is distributed to each RF control station. However, this “RF&CLK board” became the significant source of the instability in phase. Therefore a new RF reference signal oscillator was installed at J-PARC LINAC for improvement of the phase stability. This module has the 80 MHz Oven Controlled Xtal Oscillator (OCEO) and the Phase Looked Loop (PLL) under temperature control by Peltier module. The phase noise of the output signal in this module was measured by the signal source analyzer. The jitter of the output signal, which was estimated from the integration of phase noise from 10 Hz to 1 MHz, becomes about 240 fsec and was one order smaller than that of the old system (about 1700 fsec). However, the original performance of this module is expected to be better. It’s thought to be due to the 12 MHz input signal in this module. Therefore, the path of the 12 MHz master clock was optimized except for unnecessary modules. In addition, necessary modules, the O/E and E/O modules, were selected for the less phase noise in some kind of modules with the same features. Then, the jitter of the output signal in the RF reference signal oscillator improved to be about 41 fsec, which is less than one fifth that before the optimization. This value satisfies the required phase stability (+/-0.3 deg.) for the distribution system of the LLRF reference signals. For the installation of the new RF reference signal oscillator and the optimization of the distribution system, the accelerating RF power with more stable can be provided. It can be expected to improve the operating ratio in J-PARC LINAC and to suppress the activation in each device can be expected. I will introduce the new RF reference oscillator and talk about the performance of this system.

Speaker: Dr Kenta Futatsukawa (Japan Atomic Energy Agency (JAEA))

Slides LLRF2011_FutatsukawaKenta.pptx

27 1.3 GHz Phase Averaging Reference Line for Fermilab’s NML

A 1.3 GHz phase averaging reference line is being developed for Fermilab’s NML accelerator. The reference line is composed of directional couplers and 7/8” cable. The reference line is shorted at one end of the line to provide reflected signals that are summed and phase averaged with the forward signals at each directional coupler. The phase drifts of the 7/8” cable are compensated for by the phase averaging at each coupler. A method is also outlined to minimize the effects of VSWR mismatches and directivity of the directional couplers. Simulations results of the reference line are presented along with results of a scaled version of the reference line built in the lab.

Speaker: Mr Ed Cullerton (Fermilab)

Slides Reference_Line_Presentation.pptx

28 FPGA based LLRF Systems for Fermilab’s High Intensity Neutrino Source

Two LLRF systems were designed and built for the HINS program at Fermilab. The first system is used in Horizontal Test Stand for commissioning and testing of 325 MHz SRF spoke resonators. The second one is for HINS 6-cavity test accelerator with ferrite vector modulators used in a high power distribution scheme from a single klystron. In addition to standard LLRF functions, each of the systems is characterized by some unique capabilities. The HTS system has a novel resonance frequency tracking system, which may be operated in both CW and pulsed modes. And it also has built-in a real-time cavity simulator with parameterized resonance frequency and loaded Q. HINS6 LLRF provides ferrite vector modulator control on each of six cavities in the system. The nonlinear control space and initial results will be described.

Speaker: Mr Vitali Tupikov (Fermilab)

Slides HINS_LLRFs.ppt

29 RF Synchronization System Plans for The European XFEL

The European XFEL will require synchronization of RF, optical and digital subsystems with accuracies reaching levels down to 10 fs. The entire synchronization system will consist of both RF coax cable and optical distrubution links working complementary to assure the required performance and availability. The plans for the RF part of the synchronization system will be covered by this contribution. The RF synchronization system will consist of the Master Oscillator and coax cable signal distribution system. The basic ideas for the Master Oscillator design and the planned layout of the distribution links will be presented together with estimated performance.

Speaker: Dr Krzysztof Czuba (ISE, Warsaw University of Technology)

Slides KCzuba_RF_Synchr.pdf

30 Q&A

Wednesday, 19 October

Session 8

Convener: Mr Tomasz Plawski (Jefferson Lab)

31 FPGA Programming

Speaker: Dr Wojciech JALMUZNA (TUL, DMCS)

Slides WojciechJalmuzna_FPGATutorial.pdf

32 The Tevatron Years, a Retrospective

Speaker: David McGINNIS (ESS)

Slides LLRF2011McGinnis.pptx

33 First Results of the SwissFEL Injector Test Facility LLRF System

The first stage of the SwissFEL injector test facility is presently under commissioning at the Paul Scherrer Institut (PSI) in Switzerland. The injector is part of the SwissFEL project, a facility to deliver coherent, ultra-bright, and ultrafast XFEL photon beams down to the 0.1 nm wavelength ranges. The commissioning in this first phase was focused on the operation of a 2.5 cell normal conducting RF gun and two S-band travelling wave structures. In a second stage, the injector will be completed by two more S-band and one X-band (4th harmonic) travelling wave structures to boost the energy up to 250 MeV and linearize the longitudinal phase space before entering a magnetic bunch compressor. The most challenging task for the LLRF system is to maintain the tough RF tolerances in the order of 0.03 deg (rms) in S-band phase and 0.04 deg (rms) in X-band phase. A digital LLRF system has been designed and implemented with emphasis on low drift and high resolution performance in order to gain experience for the future SwissFEL LLRF system. This presentation will address the current status of the LLRF systems, present operational experiences and discuss further commissioning plans.

Speaker: Dr Thomas Schilcher (Paul Scherrer Institut)

Slides SwissFEL_LLRF.ppt

34 ITER RF Systems and diagnostics

The operation of the ITER fusion machine will rely heavily on the performance of the plasma heating systems and diagnostics system both being essential pre-requisites for the plasma control system. An extensive diagnostic system will be installed on the ITER machine to provide the measurements necessary to control, evaluate and optimize plasma performance in ITER and to further the understanding of plasma physics. These include measurements of temperature, density, impurity concentration, and particle and energy confinement times. The measurement technologies include magnetics, neutron systems, optical, spectroscopic, bolometry, and microwave systems. The microwave systems operate in the frequency range from a 5 GHz to 200 GHz and include electron-cyclotron-emission measurements for the main plasma, microwave reflectometers for for plasma position, the divertor plasma, and for the main plasma, as well as the fast wave reflectometry. These diagnostics require microwave sources, transmission systems and receiver covering the whole frequency range. The ITER Tokamak will rely on three sources of external heating that work in concert to provide the input heating power of 50 MW required to bring the plasma to the temperature necessary for fusion. These are neutral beam injection and three sources of radio frequency heating. RF heating and current drive techniques include ion cyclotron resonance frequency (ICRF, 30-65 MHz), electron cyclotron resonance frequency (ECRF, 170 GHz) and lower hybrid current drive (LHCD, 5GHz) system. The role of RF is not only for bulk plasma heating, but is now essential to optimize both the reference scenario (MHD stabilisation) and the advanced scenarios (current profile control) in ITER. The "unit" power of all the RF systems is 20 MW.

Speaker: Dr Stefan Simrock (ITER)

Slides ITER_RF_Systems_Microwave_Diagnostics_short.pdf

35 High Speed Direct Sampling Analog to Digital Converters

Speaker: Derek Redmayne (Linear Technology Corporation)

Slides crashcoursedesy.pptx

36 Q&A

11:30 Coffee break

Session 9

Convener: Dr Stefan Simrock (ITER)

37 RF system models and longitudinal beam dynamics

Speaker: Dr Themistoklis MASTORIDIS (CERN)

Slides Mastoridis_1.pdf

38 The DESY-ILC '9mA experiment' at FLASH

The corner stone of the TESLA superconducting linear accelerator technology is the ability to accelerate long bunch-trains at relatively high currents in pulsed operation with low emittance growth and low beam loss. The reference design for the International Linear Collider main linacs uses some 600 10MW klystron that each feed 26 cavities housed in three cryomodules. Two other high level rf configurations are also under consideration, namely the klystron cluster scheme (KCS) and distributed RF scheme (DRFS). We will give an overview of the three systems and consider their relative merits. Beam tests of the baseline rf configuration are the subject of the TTF/FLASH '9mA programme', led by DESY in collaboration with the ILC-GDE, and which has the goal of demonstrating and characterising operation with 800us beam pulses at 9mA average current and at the limits of gradient and rf power. Following a successful demonstration in 2009 of FLASH operation with long pulses and high average current, the programme has shifted to establishing operation close to cavity quench limits under heavy beam loading conditions. With each klystron feeding many cavities, the challenge is to achieve not just a stable vector sum but also stable gradient profiles on individual cavities. We will report on recent activities and discuss plans for future studies.

Speaker: Mr John Carwardine (Argonne National Laboratory)

Slides Carwardine_9mAexpt_LLRF2011-posted.pdf

39 Q&A

40 Industry partners presentations

13:20 Lunch / PC Lunch

Poster Session and Industrial Exhibition

41 Design and Implementation of Automatic Cavity Resonance Frequency Measurement and Tuning Procedure for FLASH and European XFEL Cryogenic Modules

Speaker: Dr Valeri Ayvazyan (DESY)

Poster Freq_Meas_VA.pdf

42 FLASH II Project: LLRF Options and Tests

Speaker: Dr Valeri Ayvazyan (DESY)

Poster LLRF_FLASH2_VA.pdf

43 Klystron Lifetime Management system. Installation at klystron test stand

Speaker: Mr Łukasz Butkowski (ISE)

Poster KLM_POSTER_2011.pdf

44 LLRF controls based on DOOCS

Speaker: Olaf Hensler (DESY)

Poster LLRFws-Poster-OlafHensler.pdf

45 Software support for PCIExpress bus for uTCA-based LLRF control system

Speaker: Mr Adam Piotrowski (Technical University of Lodz, DMCS)

Poster Poster-LLRF2011.pdf

46 LLRF Controller Implementation for uTCA based LLRF System

Speaker: Mr Wojciech Jalmuzna (DESY)

Poster poster.pdf

47 FPGA architecture of the Spiral 2 digital LLRF

Speaker: Mr Yannick Mariette (CEA Saclay)

Poster Poster_Hamburg_Spiral2_LLRF_FPGA_Architecture.pdf

48 Embedded diagnostics in the LEIR and PSB digital LLRF systems

Speaker: Dr Andrew Butterworth (CERN, Geneva)

Poster Poster_LLRF_OASIS.pdf

49 Closed loop performance of the LLRF Vector Control System for Cryo-Module 1 at the SRF test facility at Fermilab

Speaker: Dr Philip Varghese (Fermilab)

Poster LLRF2011_PhilipV_Poster.pdf

50 Superconducting Cavity Model and Simulation for Fermilab's NML

Speaker: Mr Ed Cullerton (Fermilab)

51 1.3 GHz 8 Channel Receiver with Single Channel Transmitter for Fermilab's NML

Speaker: Mr Ed Cullerton (Fermilab)

52 An electronic circuit for the protection of the Spiral-2 RF power couplers

Speaker: Mr Philippe De Antoni (CEA IRFU)

Slides PosterPkUpe_ConfLLRF_2011_Format_A0.pdf

53 ThomX LLRF

Speaker: Mr Rajesh SREEDHARAN (Synchrotron SOLEIL)

Poster ThomX_LLRF2011_v3.pdf

54 Refining narrow-band noise signals for transversal beam excitation to improve J-PARC MR slow extraction

Speaker: Dr Alexander Schnase (JAEA J-PARC Center)

Poster Poster_LLRF2011oct19_schnase.ppt

55 SELF EXCITED OPERATION FOR A 1.3 GHz 5-CELL SUPERCONDUCTING CAVITY

Speaker: Mr Michael Laverty (TRIUMF)

Poster 1.3GHzmulticell.pdf

56 200 MHz DDS RF Source for the CERN PS

Speaker: Dr Heiko Damerau (CERN)

Poster LLRF11Poster200MHzDDS.pdf

57 LLRF system for DC-SC photocathode injector at Peking University

Speaker: Dr Fang Wang (Peking University)

Poster LLRF_system_for_DC-SC_photocathode_injector_at_Peking_University.pdf

58 LLRF Commissioning of the new CEBAF 100 MeV Cryomodule

Speaker: Mr Ramakrishna Bachimanchi (Thomas Jefferson National Accelerator Facility)

59 Eight-channel Fast ADC card for Direct Sampling of GHz Signals

Speaker: Mr Samer Bou Habib (ISE, Warsaw University of Technology)

Poster Samer_Bou_Habib_LLRF2011.pdf

60 Drift Calibration Module for RF field detectors for FELs.

Speaker: Mr Jan Piekarski (Warsaw University of Technology - Institute of Electronic Systems)

Poster Drift_Calibration_Module.pdf

61 Reflectometer system for active phase drift compensation in coaxial cables

Speaker: Mr Przemyslaw Kownacki (ISE, WUT)

Poster PKownacki_Poster_DESY_10.2011.pdf

62 Vector Modulator card for the uTCA based LLRF control system

Speaker: Dr Krzysztof Czuba (ISE, Warsaw University of Technology)

Poster VM_Poster_dm_kc_.pdf

63 Hardware for LLRF Control System in MTCA Standards

Speaker: Dr Dariusz Makowski (Tech. Univ. of Lodz, DMCS)

Poster D.Makowski_poster_v10.pdf

64 Coax cable drift measurements for LLRF system

Speaker: Mr Dominik Sikora (ISE, Warsaw University of Technology)

Poster Poster_LLRF_2011.pdf

65 uTCA fast ADC board for Bunch Arrival Time Monitor signals processing

Speaker: Mr Stefan Korolczuk (The Andrzej Soltan Institute for Nuclear Studies (IPJ))

Poster skorolcz.pdf

66 LLRF Hardware architecture and performance of Fermi@Elettra

Speaker: Mr Anton Rohlev (Elettra)

Slides LLRF11_TSR.pdf

67 RF generation from optical pulse trains for the LLRF at FLASH

Speaker: Mr Thorsten Lamb (DESY)

Poster LLRF11_4.pdf

68 LLRF system for the X-band high power test stand at CERN

Speaker: Mr Luca Timeo (CERN)

Poster LLRF_system_for_the_X-band_high_power_test_stand_at_CERN.pdf

69 Introducing the multi-harmonic RF feedforward to the J-PARC synchrotrons

Speaker: Dr Masahito Yoshii (KEK/J-PARC)

Poster LLRF11_J-PARC_RCS_FF_poster.pdf

70 Error correction of IQ demodulator used at XFEL/SPRING-8 SACLA

Speaker: Dr takashi ohshima (RIKEN)

Poster iq-corr-ohshima.pdf

71 Digital LLRF for Max-IV

Speaker: Ms Angela Salom (Sincrotrone Trieste)

Poster LLRF2011_-_Poster_-_Digital_LLRF_for_Max-IV.pdf

72 An Equivalent Circuit Model for the ANL APS-U SPX Deflecting Cavities

Speaker: Tim Berenc (Argonne National Laboratory)

73 A Small-Signal Baseband Transfer Function Model for Superconducting Deflecting Cavities

Speaker: Tim Berenc (Argonne National Laboratory)

74 Normalized Small-Signal Baseband Transfer Functions for an RF Cavity

Speaker: Tim Berenc (Argonne National Laboratory)

75 INITIAL APPLICATION OF THE RHIC LLRF UPGRADE PLATFORM AT THE BNL COLLIDER-ACCELERATOR DEPARTMENT

Speaker: Mr Kevin Smith (Brookhaven National Laboratory)

Poster LLRF11_2_Initial_Application_KSS.pptx

76 DESIGN AND APPLICATION OF A FOUR CHANNEL RF ADC FOR THE RHIC LLRF UPGRADE PLATFORM

Speaker: Mr Kevin Smith (Brookhaven National Laboratory)

Poster LLRF11_3_DAC_Design_and_App_KSS.pptx

77 A DETERMINISTIC GIGABIT SERIAL TIMING, SYNCHRONIZATION AND DATA LINK FOR THE RHIC LLRF UPGRADE PLATFORM

Speaker: Mr Kevin Smith (Brookhaven National Laboratory)

Poster LLRF11_1_Update_Link_KSS.pptx

78 A New Digital Low-Level Radio Frequency Control System Implementation Based on Multi-carrier Frequency Division Multiplexing Communication Model with Pilot-Tone Channel Compensation

Speaker: Mr Hengjie Ma (ANL)

Poster SPX_LLRF_OFDM_Model_Ma_poster.pdf

79 Improvement of Bunch Arrival Time Monitor readout electronics by upgrade to uTCA

Speaker: Mr Jaroslaw Szewinski (Soltan Institute for Nuclear Studies)

Poster jszewins.pdf

80 Piezo operation experience at FLASH

Speaker: Dr Mariusz Grecki (DESY)

Poster FLASH_piezo.pdf

81 Conceptual Piezo Control System Design for European XFEL

Speaker: Mr Konrad Przygoda (TUL)

Poster LLRF2011_KP.pdf

82 The LLRF System for REGAE

Speaker: Dr Matthias Hoffmann (DESY)

Poster REGAE_LLRF_Poster.pdf

83 A Field Monitoring System of the LANSCE DTL Systems

Speaker: Mr Sungil Kwon (AOT-RFE, LANL)

Poster WEPMS022_poster_format_v2.pdf

84 Modeling Longitudinal Beam Dynamics by Combining Fourier Coefficients and Moments for Controller Design Including Beam Loading in Synchrotrons

Speaker: Ms Kerstin Gross (Technische Universität Darmstadt, Institute of Automatic Control and Mechatronics, Department of Control Theory and Robotics)

Poster GrossKerstin_PosterLLRF2011.pdf

85 Experimental results and last improvements for the LLRF superconducting cavity control system at IPNO

Speaker: Mr CHRISTOPHE JOLY (CNRS-IN2P3-IPNO)

Poster LLRF11_poster.pdf

86 Analysis of Coupling Effects observed during the February 2011 9ma run at FLASH

Speaker: Julien Branlard (DESY)

Poster 2011_10_19_-_J.Branlard_-_LLRF11_poster.pptx

87 LLRF Performance Results in Fermi@Elettra

Speaker: Mr Massimo Milloch (Sincrotrone Trieste)

Poster ID48_-_LLRF_Performance_Results_in_Fermi@Elettra_-_V6.pdf

88 Modelling, control design and simulation of a klystron amplifier at ESS-Bilbao

Speaker: Dr Tomaso Poggi (ESS-Bilbao)

Poster poster_Tomaso_Poggi.pdf

89 Digital LLRF Improvements for the NSCL Reaccelerator

Speaker: Nathan Usher (National Superconducting Cyclotron Laboratory)

Poster MSU_Poster.pdf

90 The near to continuous wave operation preparation and first test at CMTB

Speaker: Wojciech Cichalewski (TUL-DMCS)

Slides LLRF2011_nearCW_pics.pdf

18:20 Workshop Diner

Thursday, 20 October

Session 10

Convener: Dr Wolfgang HOEFLE (CERN)

91 Embedded system development

Speaker: Freddy SEVERINO (Brookhaven National Laboratory)

Slides LLRF2011_Embedded_Systems_Tutorial.pptx

92 CONCEPT AND ARCHITECTURE OF THE RHIC LLRF UPGRADE PLATFORM

The goal of the RHIC LLRF upgrade has been the development of a stand alone, generic, high performance, modular LLRF control platform, which can be configured to replace existing systems and serve as a common platform for all new RF systems with the Collider-Accelerator Department at BNL. The platform is designed to integrate seamlessly into a distributed network based controls infrastructure, be easy to deploy, and to be useful in a variety of digital signal processing and data acquisition roles. Reuse of hardware, software and firmware has been emphasized to minimize development effort and maximize commonality of system components. System interconnection, synchronization and scaling are facilitated by a deterministic, high speed serial timing and data link, while standard intra and inter chassis communications utilize high speed, non-deterministic protocol based serial links. System hardware configuration is modular and flexible, based on a combination of a main carrier board which can host up to six custom or commercial daughter modules as required to implement desired functionality. This paper will provide an overview of the platform concept, its architecture, features and benefits.

Speaker: Mr Kevin S. Smith (Brookhaven National Laboratory)

Slides LLRF11_Concept_Talk.pptx

93 A method for removal of the measurement noise caused by clock jitter in RF digital demodulation techniques.

Modern LLRF systems make use of RF sampling techniques (I/Q or non-I/Q) to feed digital processing circuits with amplitude and phase measurements of the RF signals of interest. The control of RF accelerator fields must often be performed with a high degree of precision, and the control algorithms must react with low latencies (microseconds). For these reasons, the raw measurement precision is crucial. One of the main limitations of the measurement precision in I/Q or non-I/Q sampling techniques, is the noise generated by the sampling clock jitter. To limit its effect, a high purity sampling clock generation hardware is commonly involved, in conjunction with frequency down-conversion stages. This paper discloses an easy-to-implement method which allows lowering or cancelling the contribution of the sampling clock jitter to the measurement noise. It shows modeling results, as well as experimental results obtained with the direct sampling of 700 MHz signals.

Speaker: Mr Philippe GALDEMARD (C.E.A. / Saclay , DSM/Irfu/SIS)

Slides LLRF_2011_P_Galdemard.pdf

94 Longitudinal dynamic analysis for Project X LINACs

The longitudinal dynamic analysis for Project X is very challenging. Project X has 2 LINACs with warm and cold sections, one CW and one pulsed RF LINAC. The CW LINAC has cavities operating at 3 or 4 RF frequencies, high loaded Qs of up to 3 10^7 and 20Hz bandwidths. The 3 to 8 GeV LINAC has ILC type 1.3 GHz cavities with a gradient amplitude of 25 MV/m. 13 RF Stations: 2 cryomodules with 8 cavities/cryomodule for a total of 16 cavities/RF-ST. Total Energy gain ~5 GeV. Beam current of 1 mA or 2 mA. Beam phase: -10 degrees. Minimum RF pulse of 4.3 ms flattop but also 20 to 30 ms are being considered and Qload in the order of 1e7. This work analyzes and simulates the longitudinal dynamics in the presence of major disturbances such as Lorentz force detuning, microphonics, beam loading, beam phase, etc.

Speaker: Dr Gustavo Cancelo (Fermilab)

Slides LLRF2011_Longitudinal_dynamic_analysis_for_the_3-8_GeV_pulsed_v2.pdf LLRF2011_Longitudinal_dynamic_analysis_for_the_3-8_GeV_pulsed_v2.pptx

11:00 Coffee break

Session 11

Convener: Mr Kevin Smith (Brookhaven National Laboratory)

95 One-turn delay filters in LLRF feedback controllers applied to circular accelerators: Impact on the RF station and beam dynamics and optimal configuration

High beam currents in circular accelerators lead to stability and performance limits associated with static and dynamic beam loading. Sophisticated techniques in the feedback control system of the RF stations are necessary to mitigate these effects. One-turn delay filters have been commonly included in the low-level RF feedback loops, to reduce the impedance presented to the beam by the closed loop RF station. This paper analyzes different configurations for the one-turn delay filters and evaluates the impact in both the impedance reduction and the beam dynamic characteristics of the parameters of the comb filter and LLRF feedback system. With the introduction of narrow band comb filters, small changes in LLRF parameters can have significant effects on the stability and performance of both the RF station and beam dynamics. This work summarizes previous designs, including comb filters in the PEP-II LLRF system, and addresses the optimal settings of LLRF parameters and configuration tools for the CERN LHC LLRF system including one-turn delay filers. In particular, for the LHC RF stations, it justifies the resolution in the measurement techniques to identify the parameters of the LLRF stations and presents algorithms developed to maximize the phase margin, taking into consideration the phase behavior of the closed loop system. Results from simulations and measurements are presented to validate the procedure followed. Predictions for operation and performance limitations on the RF station and beam dynamics at high beam current operation will be analyzed.

Speaker: Dr Themistoklis Mastoridis (CERN)

Slides OTDF_LLRF11_VF.pdf

96 Low-level RF consolidation of the CERN PS Complex machines

The CERN PS complex comprises machines belonging to the Large Hadron Collider (LHC) injection chain, such as the Proton Synchrotron Booster (PSB), the Proton Synchrotron (PS) and the Low Energy Ion Ring (LEIR), as well as the Antiproton Decelerator (AD). These machines share several characteristics, such as a wide frequency swing between injection and extraction, mostly low-frequency cavities (few MHz) and large synchrotron tunes. In addition, a high dynamic range (over 60 dB) in the cavity voltage control loops is often required, as well as full system configurability to allow for complex RF gymnastics, whose requirements evolve with time. The RF group has chosen to consolidate the low-level RF (LLRF) systems of these machines to improve the machine operation whilst reducing the maintenance effort. To this aim, a dedicated LLRF family based upon digital technology and digital signal processing has been deployed in 2005 in the LEIR machine. A mightier version of the family is currently under development and will be deployed in the PSB from 2012 onwards. This will also allow test and control of new cavity types, included in the high-level RF consolidation program. Last but not least, it will be applied to the recently-approved Extra Low ENergy Antiproton (ELENA) ring. We describe here the main building blocks of this LLRF family. Beam results obtained over the years in the LEIR and PSB machines are also shown, together with hints on the future challenges and plans.

Speaker: Maria Elena Angoletta (CERN)

Slides LLRF11_CERNsInjectorsRenovation_MEAngoletta.ppt

97 CW Measurements of TESLA and SC Gun Cavities with the Cornell LLRF System at HoBiCaT

In Energy Recovery Linacs, such as the Cornell ERL or BERLinPro, the main linac cavities are operated in CW at low beam-loading. The choice of the loaded Q is driven by two opposing factors. Limited RF power favors for a high external Q to allow operation at the desired field level, while a higher Q and such a narrow bandwidth leads to increasing field instability in presence of microphonics detuning or even ponderomotive instabilities. To determine the optimum coupling for ERL main Linac operation, LLRF measurements with the Cornell system were performed at HoBiCaT to study the field stability at given microphonics detuning of a TESLA cavity for different gain settings and external Q values. Stable operation at external Q up to 2e8 was demonstrated with field's phase stability of 0.02 degrees. Further, the same system was used to operate a SC 1.6 cell gun cavity in CW mode. Results of the measured field stability, microphonics detuning and first studies of beam parameters will be presented as well.

Speaker: Dr Axel Neumann (Helmholtz-Zentrum Berlin)

Slides Neumann_LLRF2011.pptx

98 ANL APS-U SPX LLRF System*

The Short-Pulse X-ray (SPX) system within Argonne National Laboratory’s (ANL) Advanced Photon Source Upgrade (APS-U) project will use Zholents’ transverse radio-frequency (rf) chirp scheme to produce picosecond time-scale x-ray pulses at the APS. This scheme will utilize two sets of superconducting rf deflecting cavities installed in the APS storage ring: one set to produce transverse beam motion and the second set to cancel the motion. The requirements, plans, and status of the SPX LLRF system will be presented. *Work supported by U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.

Speaker: Tim Berenc (Argonne National Laboratory)

Slides LLRF2011_SPX_Final.pptx

99 Requirements and parameters for LLRF system at ESS

The LLRF design is undergoing at ESS where about 200 LLRF stations are expected to be built by the year 2019 for a variety of RF cavities such as RFQ, DTL, spoke and elliptical superconducting cavities, which are planned to be individually powered, i.e.one klystron per cavity in current design. It is essential to identify and recognize the requirement, issues and challenges to be addressed in LLRF system, as well as to define the interface parameters. In this presentation, we will describe the strigent demands of ESS on LLRF system and the proposed solutions, and the key parameters to be identified. Moreover, we are keen to look for the suggestions and comments from LLRF community.

Speaker: Mr Rihua Zeng (European Spallation Source ESS AB)

Slides LLRF_Requirement_and_parameters_at_ESS.pdf

100 Q&A

Closure

13:20 Lunch break

101 DESY visits