DESY, Hamburg
PETRA III is a new hard x-ray synchrotron radiation source which will be operated at 6 GeV with an extremely low horizontal emittance of 1 nmrad. This new facility is the result of a conversion of the existing storage ring PETRA II into a light source. The conversion comprises the complete rebuilding of one eighth of the 2304 m long storage ring, which will then house 14 undulator beam lines, the optical and experimental hutches, and the modernization and refurbishment of the remaining seven eighths. In addition two 100 m long damping wiggler sections have been installed which are required to achieve the small design emittance. Construction, installation and technical commissioning have been finished middle of March and then the commissioning with beam started. In this paper we present the results that have been achieved during commissioning with special emphasis on the role of diagnostic systems.
SSRF, Shanghai
SSRF is a 432 m-circumference synchrotron light source with a 150MeV linac, a 3.5GeV full energy booster, and a 3.5GeV storage ring. Principal diagnostics systems have been installed and nearly all have been commissioned during past two years. Data have been obtained on beam position, beam profile, current, and synchrotron radiation diagnostics beamline on the storage ring. Multi bunch transverse feedback system has been applied on the ring. Results for the 150MeV electron beams in the linac, up to 3.5GeV in the booster, and 3.5GeV in the ring will be presented.
SOLEIL, Gif-sur-Yvette
Beam orbit stability is a crucial parameter for 3rd generation light sources in order to achieve their optimum performance. Sub-micron stability is now a common requirement for vertical beam position. To reach such performance, Global Orbit Feedback Systems are mandatory. This paper describes the different design approaches for Global Orbit Feedback Systems. A few machines can use a single set of strong correctors. Most machines have their strong corrector bandwidth limited by eddy currents in aluminium vacuum chamber, or power-supplies speed or digitization granularity. Then, a second set of fast correctors is required for high frequency correction. But Fast and Slow Orbit Feedback Systems cannot work together with a common frequency range, they fight each other. An earlier solution has been to separate fast and slow systems by a frequency deadband. This approach does not allow correcting efficiently the orbit shift due to the gap movements of the increasingly sophisticated insertion devices that are installed on new machines. The different solutions that have been recently implemented are reviewed.
ESRF, Grenoble
The ESRF Storage Ring has, in the period of the last 3 winter months, been fully equiped with new electronics for its BPM system while causing a minimum disturbance to its large community of X-ray beam-line users. The Libera-Brillance is now actively doing the treatment of the weak RF signals on all of the 224 BPM stations, and has replaced the old RF-Multiplexing system that had served reliably for nearly 17 years. This paper will describe the precautions that had been taken to make the whole transition as smooth and fluid as possible, with regards to both the reliability for the SR operation and the positional stability of the X-ray beams for the users of more than 40 beamlines. Information will be given on the structure of the network and computer control, based on the Tango distributed control system and its associated device-servers and tools. Results obtained will be presented to demonstrate the strongly improved performance and functionality in every field of application, and that will make this new BPM system the key component in the near future’s upgraded orbit stabilization system.
KEK, Ibaraki
A transverse bunch by bunch feedback system using iGp feedback processors has been tested at the KEK-PF. The system consists of a bunch position detection system using 1.5 GHz components of the beam (3 x fRF), iGp feedback signal processors, and a transverse feedback kicker with a high power amplifier. It shows sufficient performance to suppress instabilities completely up to a beam current of 450mA. Results of the mode analysis of the instabilities using the grow-damp function of the iGp are also shown.
DELTA, Dortmund
The beam orbit of the 1.5GeV electron storage ring DELTA showed a variety of beam distortions with a pronounced frequency spectrum mostly caused by girder movements and ripples of the magnet power supplies. In order to enhance the orbit stability at least up to 300 Hz bandwidth a global fast orbit feedback is under consideration. As a prototype an FPGA based local fast orbit feedback at a 10 kHz data acquisition rate has been developed. The digitized orbit data are distributed from I-Tech Libera and Bergoz MX-BPMs to an FPGA board via a fibre interconnected network based on the Diamond Communication Controller [*]. The correction algorithm is written in VHDL and the corrections are applied with digital power supplies connected to the FPGA board through RS485 links. The first operational tests of the system achieved an effective damping of orbit distortions up to 350 Hz. The paper will give an overview on the layout of the FPGA based local orbit feedback system, will report on the results of the measured uncorrected orbit distortions at DELTA and the stability enhancements that could be achieved by the local feedback system.
* I. S. Uzun et al., "Initial Design of the Fast Orbit Feedback System for
Diamond Light Source", Proc. 10th ICALEPCS
CELLS-ALBA Synchrotron, Cerdanyola del Vallès
The design of the stripline kickers shall be adapted to match the line impedance, maximize the effective beam kick, reduce the heat load and minimize the transverse coupling impedance. These kickers are used for either tune measurements or transverse feedback. We describe the ALBA design of these kickers for both Booster and Storage Ring.
CERN, Geneva
The fast beam intensity measurements for the LHC are provided by eight Fast Beam Current Transformers (FBCT). Four FBCTs installed in the LHC rings are capable of providing both bunch-by-bunch and total turn-by-turn beam intensity information. A further four FBCTs, two in each of the LHC dump lines, are used to measure the total extracted beam intensity. In addition to providing intensity information the ring FBCTs also send signals to the machine protection system. This increases the complexity of both the RF front-end and the digital acquisition parts of the signal processing chain. The aim of this paper is to discuss the implemented hardware solution for the FBCT system, in particular with respect to the signal distribution, FPGA signal processing, calibration, and interaction of the FBCTs with the machine protection chain.
CERN, Geneva
The LHC circulating beam current measurement is provided by 8 current transformers, i.e. 2 DC current transformers (DCCT) and 2 fast beam current transformers (FBCT) per ring. This paper presents the DCCT, designed and built at CERN, including the sensor, the electronics and the front-end instrumentation software. The more challenging requirements are the needed resolution, of the order of 1μA rms at 1s average, and the wide dynamic range of the circulating beam intensity from the pilot bunch (8μA) to the ultimate beam (860mA). Another demanding condition is the high level of reliability and availability requested for the operation and machine protection of this highly complex accelerator. The measurement of the first RF captured beam in ring 2 is close to meet the specifications in term of resolution (1.3μA rms at 1s average) and stability over a period of a few hours (drift less than 3μA). Finally elements intended to be installed in the near future are presented.
CERN, Geneva
The LHC Beam Loss Monitoring (BLM) system is one of the most complex instrumentation systems deployed in the LHC. As well as protecting the machine, the system is also used as a means of diagnosing machine faults, and providing feedback of losses to the control room and several systems such as the Collimation, the Beam Dump and the Post-Mortem. The system has to transmit and process signals from over 4'000 monitors, and has approaching 3 million configurable parameters. This paper describes the types of configuration data needed, the means used to store and deploy all the parameters in such a distributed system and how operators are able to alter the operating parameters of the system, particularly with regard to the loss threshold values. The various security mechanisms put in place, both at the hardware and software level, to avoid accidental or malicious modification of these BLM parameters are also shown for each case.
CERN, Geneva
A discrete components design of a current digitizer based on the current-to-frequency converter (CFC) principle is currently under development at CERN. The design targets at rather high input current compared to similar designs, with a maximum equal to 200mA and a minimum of 1nA, as required by the ionization chamber that will be employed in the Proton Synchrotron and Booster accelerators as well as in the LINAC. It allows the acquisition of currents of both polarities without requiring any configuration and provides fractional counts through an ADC to increase the resolution. Several architectural choices are being considered for the front-end circuit, including charge balance integrators, dual-integrator input stages, integrators with switchable-capacitor, in both synchronous and asynchronous versions. The signal is processed by an FPGA and transmitted over a VME64x bus. Design, simulations and measurements are discussed in this article.
PSI, Villigen
This contribution gives an overview of transverse sub-micron beam position measurement systems and techniques for 3rd and 4th generation light sources and collider projects. Topics discussed include mechanical, electrical and digital design aspects, environmental influences, machine operation and design considerations, as well as system- and beam-based measurement and calibration techniques.
DESY, Hamburg
PETRA III, a new high-brilliance synchrotron radiation source, is under commissioning at DESY. Its beam position measurement system is based on the Libera Brilliance electronics. BPM system is used for machine starting up and development. The system will also be used for the beam observation and orbit feedback. This paper presents the infrastructure, features of the BPM system and experience with the commissioning of the BPM electronics.
DELTA, Dortmund
TU Dortmund University, Dortmund
Orbit stability at the 1.5 GeV electron storage ring DELTA is currently achieved via a global slow orbit feedback system at a data acquisition rate of 10 Hz. The system is based on analog Bergoz MX-BPMs and I-Tech Libera digital BPMs. In order to enhance the precision of the slow position measurement and in preparation for a global fast orbit feedback at a 10 kHz data acquisition rate we developed an FPGA based digital frontend for the MX-BPMs. The prototype module is taking orbit data from 4 Bergoz MX-BPMs, clocked to 40 kHz, at a rate of 10 kHz while averaging over 4 samples per clock cycle. The digitized data is distributed via the Diamond Communication Controller [*] formerly only available for Libera BPMs. Precision, fault tolerance and easy maintenance are the key aspects of this system. First operational tests in the storage ring showed that the system reveals the desired capabilities. The paper will give an overview on the layout of the FPGA-based system, will report on the results with beam and will show prospects for the further use at DELTA.
*I. S. Uzun et al., "Initial Design of the Fast Orbit Feedback System for Diamond Light Source", Proc. 10th ICALEPCS
NSRRC, Hsinchu
The BPM electronics of the Taiwan Light Source (TLS) have been upgraded to the Libera Brilliance in August 2008 to improve performance and functionality. Orbit feedback system is also migrated into fast orbit feedback system to enhance orbit stability. Infrastructure of the orbit acquisition system and orbit feedback system has been reconstructed to accommodate with new BPM electronics and satisfy requirements of fast orbit feedback loops. Gigabit Ethernet grouping was adopted for the data transfer rate of 10 kHz between BPM and the orbit feedback system. A summary of the efforts and performance of this upgrade will be presented in this report.
SINAP, Shanghai
KEK, Ibaraki
SR monitor for the measurements of beam profile, sizes, and bunch length has been designed and constructed at the Shanghai synchrotron radiation Facility (SSRF). A water-cooled beryllium mirror is installed to extract the visible SR. This beryllium mirror was designed via thermal analysis based on ANSYS. The extracted visible SR is relayed to dark room by three mirrors. The measurement system includes, imaging system, SR interferometers (SRI), streak camera and fast-gated camera etc are set in the dark room. Both the horizontal and the vertical beam sizes are monitored by SRI, and bunch length and temporal profile of the beam are measured by streak camera. The existed system suffers with dynamic problem for beam physics studies. The commissioning of synchrotron radiation monitor system has been performed in SSRF since December, 2007. The results obtained at SSRF will be presented.
ANL, Argonne, Illinois
This paper will give a general overview of active and passive stabilization systems, which are mainly required for future X-FEL and high energy linear colliders. Key physics requirements for beam stability for X-FELs and linear colliders will be introduced and resulting technical implications discussed. New and innovative approaches to the design and development of state-of-the-art linear accelerator components and stabilization systems will be reviewed, and recent results shown from selected prototypes and new machine installations.