Global Orbit Feedback System for the SLS Storage Ring (original) (raw)

Design of a fast global orbit feedback system for the Advanced Light Source

PACS2001. Proceedings of the 2001 Particle Accelerator Conference (Cat. No.01CH37268), 2000

The fast stability of the closed orbit of the electron beam at the Advanced Light Source (ALS) at Lawrence Berkeley National Laboratory fulfills user requirements so far without any fast active correction system. In the range between 0.1 and 500 Hz the integrated rms closed orbit motion is significantly below one tenth of one sigma beamsizes. For the future there is some user demand to improve this stability further. Moreover, the expansion of the capabilities of the ALS creates new sources of closed orbit noise. Therefore the design of a fast, global orbit feedback system has been started in conjunction with a general upgrade of the ALS control system. It will initially operate with an update rate of 500 Hz-1 kHz, will include 24 beam position monitors and corrector magnets in each plane and will use standard computer and networking architecture. The system design, measurements of transfer functions and tests with small prototype systems will be presented.

A PRELIMINARY STUDY ON HIGH PRECISION PHOTON BEAM POSITION MONITOR DESIGN FOR LOCAL FEEDBACK SYSTEMS

In the last generation of SR sources, a great effort has been spent on beam stability improvements. For the incoming users' requests, also the photon beam position in each beamline is controlled in various facilities. Local bump orbit feedback systems are actually under development for improving the stability of the delivered radiation. Photon Beam Position Monitors (PBPM) are used to detect the beam motions at low and high frequency and their performance play a key role for a successful local feedback system. In this scenario the design of the PBPM becomes a great challenge for the high precision and sensitivity requested. A lot of real error sources, as bending magnet contamination, electrical noise, mechanical tolerances and crosstalks, affect and degrade the performances of the actual devices. Starting from a background of operational experience using these devices, a preliminary study for a new generation of photon beam position monitors is presented in this paper. Some possible solutions, suitable to overcome the actual PBPM problem, are proposed.

User Operation and Upgrades of the Fast Orbit Feedback at the SLS

Proceedings of the 2005 Particle Accelerator Conference, 2005

A report on the performance of the fast orbit feedback (FOFB) in its 2nd year of user operation is given. Photon beam position monitors (XBPM) have been included by means of a slow feedback which changes the reference settings of the FOFB. Users are permitted to change the XBPM references within certain limits while the feedback is running. A fast synchronous readout of the XBPMs allows their integration into the FOFB loop. The FOFB will be extended by an additional beam position monitor (BPM) in order to satisfy the requirements of the upcoming FEMTO project.

Design of a fast orbit feedback for SOLEIL

SOLEIL is a third generation light source under construction. Great care is taken at all levels of the machine design in order to reach beam stability at the micrometer level. In particular, a fast global closed-orbit feedback is foreseen for suppressing remaining beam vibrations up to 100 Hz.

Commissioning Results of Slow Orbit Feedback Using Pid Controller Method for Siam Photon Source

Presented at, 2012

A slow orbit feedback (SOFB) system has been developed to improve the orbit stability of the Siam Photon Source (SPS) storage ring. The SOFB uses a PID controller method utilizing LabVIEW channel to access 20 BPMs and 28 correctors of the ring. The first phase implementation of the feedback loops based on this method was operated at 0.05Hz sampling frequency, which reduces the fluctuation of both horizontal and vertical positions of the orbit from ~100-200 microns down to ~15-30 microns. The commissioning results indicate that further work and hardware upgrade are required. A higher sampling frequency up to 30-50Hz is strongly necessary for PID controller implementation. Upgrading of the existing 12-bit resolution corrector power supplies is also needed. The basic principle of PID algorithms, hardware, software and commissioning results of the current SOFB system, as well as future development plans, will be presented.

The ELETTRA Fast Digital Local Orbit Feedback

An overview is given of the ELETTRA Fast Digital Local Orbit Feedback system. The system has been developed to stabilize the electron orbit in the Insertion Device straight sections. It uses two Photon Beam Position Monitors as detectors and four corrector magnets to act on the electron beam. The controller relies on a Digital Signal Processor (DSP) system based on commercial VME boards and is completely integrated in the ELETTRA Control System. A powerful workbench based on Matlab has been developed and provides complete control of the DSP from any control room workstation. The performance of the closed loop using a Proportional Integral Derivative (PID) controller is in good agreement with the simulations carried out with the system model and shows an attenuation of the noise frequency components up to 150 Hz. A newly developed technique adopts dedicated selective filters to effectively suppress the persistent periodical components of the beam noise. First experiments have also be...

Integration of orbit control with real-time feedback

Proceedings of the 2003 Bipolar/BiCMOS Circuits and Technology Meeting (IEEE Cat. No.03CH37440), 2003

The Advanced Photon Source uses two distinct control programs for orbit control and stability-a full-featured workstation-based program for orbit control (sddscontrollaw) and an EPICS-based system, the Real-Time Fast Feedback System (RTFS), to reduce orbit motion. The sddscontrollaw program has been ported to EPICS and moved from the UNIX environment to an EPICS IOC attached to the RTFS. This EPICS-based program uses the RTFS's reflective memory to gather beam position information and write corrector power supplies, thus avoiding variable network latencies. This allows the orbit control to run at a correction rate 50 times that of the workstation implementation, which virtually eliminates orbit motion caused by insertion device gap changes. Issues raised by the integration of orbit control into the real-time feedback system and performance improvements are discussed.

Status of longitudinal feedback system for the PLS storage ring

Proceedings of the 1999 Particle Accelerator Conference (Cat. No.99CH36366), 1999

The Pohang Light Source (PLS) storage ring was originally designed to store the beam current up to 400 mA at 2.0 GeV. But owing to the interactions between the HOMs of RF cavities and bunched beams which make the coupled bunch mode instabilities (CBMIs) such as dipole, quadrupole, and sextupole modes, the beam current can be stored up to 200 mA. Thus, a longitudinal feedback system (LFS) using parallel digital signal processors has been installed to cure those CBMIs at the PLS storage ring. This programmable LFS is useful for various beam diagnostics as well as for the cure of the CBMIs. At present, via this LFS, we have obtained the various useful bunch-bybunch diagnostic information such as growth rates of the instabilities, beam pseudo spectra, HOM frequencies of R-F cavities which generate the CBMIs, the threshold beam currents, and the dependence on RF cavities temperatures.

Simulator of Global Orbit Feedback System for PLS

2001

We have carried out the basic research for the accelerator and tokamak control system based on the Experimental Physics and Industrial Control System (EPICS). The EPICS is used widely in the accelerator systems where the hard real-time field, wide range and large integrated facilities are required. We have used the process database and the state notation language (SNL) in the EPICS to develop the simulator which represents as a virtual machine. In this paper, we introduce the simulator of the global orbit feedback system as an example. This simulates the global orbit feedback system under the constraint conditions for Pohang Light Source (PLS) storage ring. We describe the details of the feedback algorithm and the realization of the simulator.

Architecture of the APS Real-Time Orbit Feedback System

The APS Real-Time Orbit Feedback System is designed to stabilize the orbit of the stored positron beam against low-frequency sources such as mechanical vibration and power supply ripple. A distributed array of digital signal processors is used to measure the orbit and compute corrections at a 1kHz rate. The system also provides extensive beam diagnostic tools. This paper describes the architectural aspects of the system and describes how the orbit correction algorithms are implemented. 1 Introduction The APS is the foremost third-generation synchrotron light source in the United States, delivering intense x-rays to as many as 35 insertion-device and 35 bending-magnet beamlines. As with other light sources, orbit stability is critical in order to achieve the optimum performance for the x-ray users. At APS the rms orbit motion must not exceed 5% of the beam size, translating to limits of 17m rms horizontally and 4.5m rms vertically. The APS real-time orbit feedback system provides rea...