S. Y. Hsu

Commissioning of FPGA‐based Transverse and Longitudinal Bunch‐by‐Bunch Feedback System for the TLS

Multi‐bunch instabilities deteriorate beam quality, increasing beam emittance, or even causing beam loss in the synchrotron light source. The feedback system is essential to suppress multi‐bunch instabilities caused by the impedances of beam ducts, and trapped ions. A new FPGA based transverse and longitudinal bunch‐by‐bunch feedback system have been commissioned at the Taiwan Light Source recently, A single feedback loop is used to simultaneously suppress the horizontal and the vertical multi‐bunch instabilities. Longitudinal instabilities caused by cavity‐like structures are suppressed by the longitudinal feedback loop. The same FPGA processor is employed in the transverse feedback and the longitudinal feedback system respectively. Diagnostic memory is included in the system to capture the bunch oscillation signal, which supports various studies.

Updating the Synchrotron Radiation Monitor at TLS

The synchrotron radiation monitor provides useful information to support routine operation and physics experiments using the beam. Precisely knowing the profile of the beam helps to improve machine performance. The synchrotron radiation monitor at the Taiwan Light Source (TLS) was recently upgraded. The optics and modeling were improved to increase the accuracy of measurement in the small beam size. A high‐performance IEEE‐1394 digital CCD camera was used to improve the quality of images and extend the dynamic range of measurement. The image analysis is also improved. This report summarizes status and results.

Status of the Superconducting Insertion Device Control at TLS

Superconducting insertion devices are installed at Taiwan Light Source to meet the rapidly growing demand of X‐ray users. A control system supports the operation of all these superconducting insertion devices. Control system coordinates the operation of the main power supply and the trimming power supply to charge/discharge the magnet and provide essential interlock protection for the coils and vacuum ducts. Quench protection and various cryogenic interlocks are designed to prevent damage to the magnet. A friendly user interface supports routine operation. Various applications are also developed to aid the operation of these insertion devices. Design consideration and details of the implementation will be summarized in this report.

New Transverse Bunch-by-Bunch Feedback System at TLS

An FPGA based transverse bunch‐by‐bunch feedback system was implemented and commissioned to replace the existing analog transverse feedback system in order to suppress more effectively multi‐bunch instabilities caused by the resistive wall of the vacuum chamber, cavity‐like structures and ions related instability. This system replaces existing analog transverse feedback system to enlarge the tunability of the working point. Lower chromaticity is possible with feedback system that is very helpful for injection efficiency improvement. Top‐up and high current operation is benefit for this upgrade. One feedback loop suppresses horizontal and vertical multi‐bunch instabilities simultaneously. The clean and simple structure makes the system simple and reliable. This study also presents the preliminary result of commissioning the new transverse feedback system.

Current Status of the Beam Position Monitoring System at TLS

The beam position monitoring system is an important part of a synchrotron light source that supports its routine operation and studies of beam physics. The Taiwan light source is equipped with 59 BPMs. Highly precise closed orbits are measured by multiplexing BPMs. Data are acquired using multi‐channel 16‐bit ADC modules. Orbit data are sampled every millisecond. Fast orbit data are shared in a reflective memory network to support fast orbit feedback. Averaged data were updated to control database at a rate of 10 Hz. A few new generation digital BPMs were tested to evaluate their performance and functionality. This report summarizes the system structure, the software environment and the preliminary beam test of the BPM system.

Integration of the Longitudinal Feedback System in NSRRC

An operation version of longitudinal feedback baseband processing electronics was implemented. The system consists of a bunch phase detector, a 500‐MS/s analog‐to‐digital converter and demultiplexer module (ADC/DEMUX), DSP modules, a digital‐to‐analog converter and multiplexer module (DAC/MUX), and an RF modulator. The ADC/DEMUX unit has a fast ADC that digitizes the bunch phase signal. The down‐sampled phase error data of each bunch are then distributed to the DSP boards to perform filtering and applied control rule. In the DAC/MUX, bunch kick signals are converted into analog signals for bunch phase feedback. Design and implementation of the system will be summarized in this report.

Applications of the IEEE-1394 CCD Camera for Beam Diagnostics in NSRRC

A new generation digital CCD camera with IEEE‐1394 interface has been adopted for the diagnostics purpose recently. The applications include synchrotron radiation monitor of the booster synchrotron, synchrotron radiation monitor of the storage ring, and the intensified digital camera for transient profile measurement. Wider dynamic range and the flexibility of the digital camera provide various functional enhancements for the diagnostics purpose. The effort and achievement will be summarized in this report.

Control system for the superconducting insertion devices of NSRRC

To enhance hard X-ray production in the 1.5 GeV storage ring of NSRRC to serve the rapidly growing X-ray user community in Taiwan, the storage ring are planed to install up to five superconducting insertion devices. A 6 Tesla superconducting wavelength shifter was installed in mid-2002. A 3.2 Tesla superconducting multipole wiggler will be installed in the fall of 2003. The project for the other three multipole wigglers is launched. The control system had been implemented to support the operation of the superconducting insertion devices. The control system play a role to coordinate the operation of the main power supply and the trimming power supplies to charge/discharge the magnet and provide interlock protection for the magnet coils and vacuum ducts. A friendly user interface and various application programs are used to support routine operation. Design considerations and details of the implementation are also presented.