Local feedback experiment in the Taiwan Light Source (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.

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...

Global Orbit Feedback System for the SLS Storage Ring

Experiments at the SLS (Swiss Light Source) require a highly stabilized photon beam spot with high brilliance. In order to achieve this goal orbit oscillations due to ground motion amplified by girder resonances have to be reduced. The beam motion has to be kept below 1 µm at the insertion devices. A fast closed orbit feedback will be implemented to suppress these oscillations over a frequency range of up to 100 Hz. Digital signal processors will read the digitized beam positions and apply the data to a feedback algorithm using Singular Value Decomposition (SVD) and PID controller algorithms. The computing power of the global orbit feedback system is distributed around the storage ring and therefore requires data exchange of beam positions from one sector to another with high speed. Theoretical studies on the feedback loop have shown that a sampling rate of 4 kS/sec is needed. The proposed layout of the global orbit feedback system will be presented.

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.

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.

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...

The design of the ELETTRA fast local feedback system

Proceedings of the 1997 Particle Accelerator Conference (Cat. No.97CH36167), 1998

The stability of the electron beam position is one of the main issues for third generation synchrotron radiation sources. A fast local feedback system based on digital signal processing techniques has been designed and installed on ELETTRA. After a characterization of the main system components, the design choices are presented. The software environment used for system development and measurements is described.

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.

Overview of Some Feedback & Control Systems at Synchrotron Soleil

2016

This paper gives an overview of some feedback & control systems at Synchrotron SOLEIL that are in use or in development today. Beam stability is crucial and adressed in all SOLEIL aspects; Fast Orbit Feedback is a multi-input multi-output control system made to stabilize beam position perturbations in the low- & high frequency band. In addition, active RF cavities are used to maintain stable beam energy & spread as well as keeping electron density even throughout the storage ring. Beam stability also comes from feedforward non-linear control in particle trajectory compensation on both sides of electromagnetic undulators. On some beamlines, multi-actuator piezos or pneumatics are used to regulate photon flux to keep within detector operating range; a method to maximize the photon flux while still keeping below detector damage thresholds. Currently in development & at the sample stage level, the Nanoprobe Project collaboration (MAXIV & SOLEIL) focuses on sample stabilization during st...