| Paper |
Title |
Page |
| TUPCH186 |
Low Level RF System Development for SOLEIL
|
1447 |
| |
- P. Marchand, M.D. Diop, F. Ribeiro, R.S. Sreedharan
SOLEIL, Gif-sur-Yvette
- M. Luong, O. Piquet
CEA, Gif-sur-Yvette
|
|
| |
The Low Level RF system that is used in the SOLEIL storage ring consists in fully analog "slow" amplitude, phase and frequency loops, complemented with a direct RF feedback. A fast digital FPGA-based I/Q feedback, currently under development, will be implemented later on. The performance of both systems has been evaluated using a Matlab-Simulink-based simulation tool. The computed and first experimental results are reported.
|
|
| TUPCH187 |
DSP-based Low Level RF Control as an Integrated Part of DOOCS Control System
|
1450 |
| |
- V. Ayvazyan, A. Brandt, O. Hensler, G.M. Petrosyan, L.M. Petrosyan, K. Rehlich, S. Simrock, P. Vetrov
DESY, Hamburg
|
|
| |
The Distributed Object Oriented Control System (DOOCS) has been developed at DESY as a control system for TTF/VUV-FEL. The DSP based low level RF control system is one of the main subsystems of the linac. Several DOOCS device servers and client applications have been developed to integrate low level RF control into the TTF/VUV-FEL control system. The DOOCS approach defines each hardware device as a separate object and this object is represented in a network by a device server, which handles all device functions. A client application can have access to the server data using the DOOCS application programming interface. A set of generic and specially devoted programs provide the tools for the operators to control the RF system. The RF operation at the linac is being automated by the implementation of DOOCS finite state machine servers.
|
|
| TUPCH188 |
Phase Stability of the Next Generation RF Field Control for VUV- and X-ray Free Electron Laser
|
1453 |
| |
- F. Ludwig, M. Hoffmann, H. Schlarb, S. Simrock
DESY, Hamburg
|
|
| |
For pump and probe experiments at VUV- and X-ray free electron lasers the stability of the electron beam and timing reference must be guaranteed in phase for the injector and bunch compression section within a resolution of 0.01 degree (rms) and in amplitude within 1 10-4 (rms). The performance of the field detection and regulation of the acceleration RF directly influences the phase and amplitude stability. In this paper we present the phase noise budget for a RF-regulation system including the noise characterization of all subcomponents, in detail down-converter, ADC sampling, vector-modulator, master oscillator and klystron. We study the amplitude to phase noise conversion for a detuned cavity. In addition we investigate the beam jitter induced by these noise sources within the regulation and determine the optimal controller gain. We acknowledge financial support by DESY Hamburg and the EUROFEL project.
|
|
| TUPCH189 |
FPGA-based RF Field Control at the Photocathode RF Gun of the DESY VUV-FEL
|
1456 |
| |
- E. Vogel, W. Koprek, P. Pucyk
DESY, Hamburg
|
|
| |
At the DESY Vacuum Ultraviolet Free Electron Laser (VUV-FEL) bunch peak current and the SASE effect are (amongst other parameters) sensitive to beam energy and beam phase variations. The electron bunches are created in an rf gun, which does not have field probes. Variations of the gun rf field cause beam energy and phase variations. They have a significant influence on the overall performance of the facility. DSP based rf field control used previously was only able to stabilize the rf output of the klystron. This was due to the lack of processing power and the over-all loop delay. The controller was not able to provide satisfactory rf field stability in the gun. Replacing the DSP hardware by the new FPGA-based hardware Simulation Controller (SimCon), we are able to reduce the latency within the digital part significantly allowing for higher loop gain. Furthermore SimCon provides sufficient processing power for calculating a probe signal from the forward and reflected power as input for PI and adaptive feed forward (AFF) control. In this paper we describe the algorithms implemented and the gun rf field stability obtained.
|
|
| TUPCH190 |
Universal Controller for Digital RF Control
|
1459 |
| |
- S. Simrock
DESY, Hamburg
- W. Cichalewski, M.K. Grecki, G.W. Jablonski
TUL-DMCS, Lodz
- W.J. Jalmuzna
Warsaw University of Technology, Institute of Electronic Systems, Warsaw
|
|
| |
Digital RF control systems allow to change the type of controller by programming of the algorithms executed in FPGAs and/or DSPs. It is even possible to design a universal controller where the controller mode is selected by change of parameters. The concept of a universal controller includes the self-excited-loop (SEL) and generator driven resonator (GDR) concept, the choice of I/Q and amplitude or phase control, and allows for different filters (including Kalman filter and method of optimal controller synthesis) to be applied. Even time-varying mixtures of these modes are possible. Presented is the implementation of such a controller and the operational results with a superconducting cavity.
|
|
| TUPCH191 |
Considerations for the Choice of the Intermediate Frequency and Sampling Rate for Digital RF Control
|
1462 |
| |
- S. Simrock, M. Hoffmann, F. Ludwig
DESY, Hamburg
- M.K. Grecki, T. Jezynski
TUL-DMCS, Lodz
|
|
| |
Modern FPGA-based rf control systems employ digital field detectors where an intermediate frequency (IF) in the range of 10 to more than 100 MHz is sampled with a synchronized clock. Present ADC technology with 14-16 bit resolution allows for maximum sampling rates up to 250 MHz. While higher IF's increase the sensitivity to clock jitter, lower IF frequencies are more susceptible to electromagnetic noise. The choice of intermediate frequency and sampling rate should minimize the overall detector noise, provide high measurement bandwidth and low latency in field detection, and support algorithms for optimal field estimation.
|
|
| TUPCH193 |
Low Level RF Control System Modules for J-PARC RCS
|
1465 |
| |
- A. Schnase, M. Nomura, F. Tamura, M. Yamamoto
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
- S. Anami, E. Ezura, K. Hara, C. Ohmori, A. Takagi, M. Yoshii
KEK, Ibaraki
|
|
| |
After completing the design phase, the VME modules for the Low Level RF Control (LLRF) of the Rapid Cycling Synchrotron of J-PARC are now in the production and debugging phase. First all modules are tested for basic functionality, for example dual harmonic signal generation. Then sets of modules are connected together to check higher-level functions and feedback. Finally, the LLRF modules are interfaced to high voltage components like amplifiers and cavities. We present the results of these tests, the test methods and test functions on several levels. This way we simulate beam operation working conditions and gain experience in controlling all parameters.
|
|
| TUPCH194 |
Analogue and Digital Low Level RF for the ALBA Synchrotron
|
1468 |
| |
- F. Pérez, H. Hassanzadegan, A. Salom
ALBA, Bellaterra
|
|
| |
ALBA is a 3 GeV, 400 mA, 3rd generation Synchrotron Light Source that is in the construction phase in Cerdanyola, Spain. The RF System will have to provide 3.6 MV of accelerating voltage and restore up to 540 kW of power to the electron beam. Two LLRF prototypes are being developed in parallel, both following the IQ modulation/demodulation technique. One is fully based on analogue technologies; the other is based on digital FPGA processing. The advantages of the IQ technique will be summarised and the control loop logic described. The hardware implementation in analogue as well as in digital format will be presented and first test results shown. The implementation of the same logic with both technologies will give us a perfect bench to compare, and use the better of them, for the final LLRF of the ALBA synchrotron.
|
|
| TUPCH195 |
The LHC Low Level RF
|
1471 |
| |
- P. Baudrenghien, G. Hagmann, J.C. Molendijk, R. Olsen, A. Rohlev, V. Rossi, D. Stellfeld, D. Valuch, U. Wehrle
CERN, Geneva
|
|
| |
The LHC RF consists in eight 400 MHz superconducting cavities per ring, with each cavity independently powered by a 300 kW klystron, via a circulator. The challenge for the Low Level is to cope with both very high beam current (more than 1A RF component) and excellent beam lifetime (emittance growth time in excess of 25 hours). For each cavity we have a Cavity Controller rack with two VME crates implementing a strong RF Feedback, a Tuner Loop with a new algorithm, a Klystron Ripple Loop and a Conditioning system. In addition each ring has a Beam Control system (four VME crates) including Frequency Program, Phase Loop, Radial Loop and Synchronization Loop. A Longitudinal Damper (dipole and quadrupole mode) acting via the 400 MHz cavities is included to reduce emittance blow-up due to filamentation following phase and energy errors at injection. Finally an RF Synchronization system implements the bunch into bucket transfer from the SPS into each LHC ring. When fully installed in 2007 the whole system will count over three hundreds home-designed VME cards of twenty-three different models installed in fourty-five VME crates.
|
|
| TUPCH196 |
Digital Design of the LHC Low Level RF: the Tuning System for the Superconducting Cavities
|
1474 |
| |
- J.C. Molendijk, P. Baudrenghien, A. Butterworth, E. Ciapala, R. Olsen, F. Weierud
CERN, Geneva
- R. Sorokoletov
JINR, Dubna, Moscow Region
|
|
| |
The low level RF systems for the LHC are based extensively on digital technology, not only to achieve the required performance and stability but also to provide full remote control and diagnostics facilities needed in a machine where most of the RF system is inaccessible during operation. The hardware is based on modular VME but with additional low noise linear power supplies and a specially designed P2 backplane for timing distribution and fast data interchange. Extensive design re-use and the use of graphic FPGA design tools have streamlined the design process. A milestone was the test of the tuning system for the superconducting cavities. The tuning control module is based on a 2M gate FPGA with on-board DSP. Its design and functionality are described, including features such as automatic measurements of cavity characteristics and transient response of the tuning system. The tuner control is used as a test bed for LHC standard software components. A full 'vertical slice' from remote application down to the hardware has been tested. Work is ongoing on the completion of other modules and building up the software and diagnostics facilities needed for RF system commissioning.
|
|
| TUPCH200 |
Amplitude Linearizers for PEP-II 1.2 MW Klystrons and LLRF Systems
|
1480 |
| |
- D. Van Winkle, J. Browne, J.D. Fox, T. Mastorides, C.H. Rivetta, D. Teytelman
SLAC, Menlo Park, California
|
|
| |
The PEP-II B-factory has aggressive current increases planned for luminosity through 2008. At 2.2 A (HER) on 4 A (LER) currents, longitudinal growth rates will exceed the damping rates achievable in the existing low level RF and longitudinal low mode feedback systems. Klystron gain non-linearity has been shown to be a key contributor to these increased growth rates through time domain non-linear modeling and machine measurements. Four prototype klystron amplitude modulation linearizers have been developed to explore improved linearity in the LLRF system. The linearizers operate at 475 MHz with 15 dB dynamic range and 1 MHz linear control bandwidth. Results from lab measurements and high current beam tests are presented. Future development progress and production designs are detailed.
|
|
| WEXPA03 |
Digital Low Level RF
|
1847 |
| |
- M.-E. Angoletta
CERN, Geneva
|
|
| |
The demand on high stability and precision on the RF voltage for modern accelerators, as well as better diagnostics, maintenance and flexibility is driving the community to develop Digital Low Level RF systems (DLLRF) for the new linear accelerators, but also for synchrotrons. An overview of the state of the art in digital technologies applied to DLLRF systems and an overview of the different designs developed or in development at the different labs will be presented.
|
|
|
Transparencies
|