C. J. Wang

Digital global orbit feedback system developing in SRRC

The digital global orbit feedback system for the storage ring of SRRC has been upgraded in terms of its feedback bandwidth extension by increasing its data acquisition sampling rate and compensating eddy current effect of vacuum chamber with filter. This orbit feedback system has been applied incorporate with the insertion devices operation, such as U5 undulator and engineering model adjustable phase undulator. Elimination of orbit drift and low frequency oscillation is a continuing effort.

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.

The design schemes of graphic user interface database and intelligent local controller in the SRRC control system

Abstract The control system of the SRRC has been utilized to facilitate commisioning since the beginning, and it provides operators an easy to use environment. Hence, we would like to discuss the design schemes and relationships between the users interface, the database and the ILC (Intelligent Local Controller) levels. The whole control system in SRRC is a two-level design connected by Ethernet. From operators view, the upper level is the CONSOLE level and the lower one is the ILC level. Those signals from, or to, equipment are connected to ILCs through analog/digital interfaces, GPIB buses, RS232 serial links, etc.; the ILC is an IEEE 1014 bus (VMEbus) based system running PSOS + real-time multi-tasking kernel and PNA + (TCP/IP protocols) communication software. The control software of CONSOLE level is developed in the VMS operating system on DEC workstations, and The Graphic User Interfaces are built on the X-Window/Motif environment. The control system has fulfilled the expectations of the facility commissioning group. It has also proved to be a simple, stable, accurate, easily maintained system.

Forensic Analysis of Popular Chinese Internet Applications

When the Digital Evidence Search Kit (DESK) was first used in Mainland China, it was found to be inadequate because it did not support criminal investigations involving popular Internet applications such as QQ, MSN and Foxmail. This paper discusses the enhancements made to DESK to conduct forensic analyses of QQ, MSN and Foxmail.

Virtual instrumentation interface for SRRC control system

Virtual instrumentation system has been developed for the control system of SRRC. Almost of the measurement instruments are to provide IEEE-488 interface, they are distributed around the accelerator facilities, the virtual instrumentation system connects these instruments by local area network, Ethernet, to GPIB adapter. The man-machine interface developed by using LabVIEW, which is running at Suns workstation. The workstation to be played as an instrument server, the operator can access remote instruments simply by point and click operation. The information provided by instruments can be analyzed and extracted the desire machine parameters at workstation. The main control system can access these parameters by standard network protocol. The major goals of the virtual instrumentation interface are to provide the automatic measurement of the machine parameters and to minimize the interlude of the machine physicists and operators. Machine parameters, such as tune, beam spectrum, filling pattern, bunch length, can be online displayed at main control panel or archived for various applications.

Study of the White circuit tracking performance in the booster synchrotron of SRRC

Tracking performance of the White circuit is very important for the operation of booster synchrotron. An intensive White circuit tracking performance study in the upgraded SRRC booster synchrotron was performed. Tune is the most sensitive parameter that relative to the White circuit tracking. Tune variation during energy ramping reflects the tracking condition. We investigate tracking performance by observed tune variation and perform tune correction. The tracking performance and its improvement will be summarized in this report.

Performance of the rejuvenated injector control system in SRRC

The original injector control system is a turnkey design and it was separated from the storage ring control system. It is not easy to maintain and install new devices. The control system of injector has been rejuvenated recently. There are two basic requirements for this plan, to provide more efficient and stable light source operation, and to reduce the maintenance resource need. Its implementation will also be helpful for improvement on reliability and control response time. Upgrade injector from 1.3 GeV to 1.5 GeV will be done before the end of 1999. The renewed injector control system will be able to provide improved environment for application program development and new devices installation. Automatic control operation for full energy injection will be implemented in SRRC.

Beam position monitoring system for the 1.5 GeV transport line of NSRRC

The extracted 1.5 GeV electron beams from the booster synchrotron are transported via a transport line and injected into the storage ring. This booster-to-storage ring transport line equipped with seven stripline beam positions monitors. Commercial log-ratio BPM electronics were adopted to process the 500 MHz bunch signal directly. The position of the passing beam is digitized by VME analog interface. This report addresses the system architecture, software tools, and performance of the BTS trajectory measurement. This system will provide an elegant tool for optimizing the performance of the transport line. Preliminary results and possible applications are included.

Control issues of insertion devices

Insertion devices play crucial roles in new generation light source. Magnetic performance is the most important consideration factor during the design and construction phase. However, control performance is also an important issue from operation point of view. Motion control performance, residual field compensation scheme and control response time for continuous change in gap or phase during energy scan scenario is typical consideration to evaluate control performance of insertion devices. How to eliminate orbit excursion due to gap or phase change is also an important issue. Various methods have been used to address the problems. Detailed of these issues about insertion devices control are discussed.

New control system for the 50 MeV linear accelerator of TLS

The pre-injector of the Taiwan Light Source (TLS) is consists of a 140 kV thermionic gun and a 50 MeV travelling wave type linear accelerator (linac) system. A linac control system has been renewed to avoid obsolescence. It is also utilized to improve performance, decouple the vacuum interlock logic from the linac control system, and provide a better control functionality for top-up operation. One VME crate system is dedicated for the linac control, the new hardware equipped with high resolution of analogue interface to provide better control. Vacuum interlock logic will be done via a dedicated programmable logic controller (PLC). The remained linac devices, which are necessary for sequential control such as door access interlock, klystron warm up, gun warm up, trigger interlock, gun high voltage interlock, klystron modulator high voltage interlock, water flow interlock, will be done by another PLC. Both interlock and sequential control of PLC will be controlled by the VME crate. All of the other functions without interlock or sequence requirement will be controlled by the VME crate directly as well. New control system is expected to provide better control functionality, better performance, easy for maintenance, and useful easy to add new hardware equipments.