Jenny Chen

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.

Improvements to the injection efficiency at the Taiwan Light Source

The Taiwan light source began top-up operation in October 2005 with an initial beam current of 200 mA. This was subsequently raised to 300 mA. In the early phase of top-up operation, the injection efficiency varied markably under different machine operating conditions. A procedure to optimize and maintain the injection efficiency is presented. Future improvements and the prospects for a 400 mA top-up operation are discussed.

Beam position monitoring system upgrade for the TLS

Taiwan light source (TLS) is equipped with 59 beam position monitors (BPM). The existing Bergoss multiplexing BPM electronics are working well during the last decade. To improve the functionality of the BPM system, Libera electron will be employed to replace some existing multiplexing BPM electronics to enhance system functionalities. Reflective memory is also applied to seamlessly integrate two kinds of electronics in the meanwhile. The high precision closed orbits were measured by multiplexing BPM via multi-channel PMC form factor 16-bits ADC modules and gigabit Ethernet fast access channels of Libera electron. Turn-by-turn beam position measurement is also supported by new BPM electronics. Tune measurement is also possible by spectra analysis of the turn-by-turn beam position data. The preliminary version of the orbit data was sampled every millisecond. Fast orbit data were shared by reflective memory network for fast orbit feedback application. Averaged data were updated to control database at a rate of 10 Hz. The system structure, software environment and preliminary beam test of the BPM system are summarized in this report.

Operation experiences of the bunch-by-bunch feedback system for TLS

Severe multi-bunch instabilities have deteriorated the performance of Taiwan light source (TLS) during the operation since SRF system upgrade in 2004. FPGA-based bunch-by-bunch feedback system was commissioning during late 2005 and early 2006. Multi-bunch instabilities in both transverse and longitudinal are damped effectively. Delivery up to 400 mA stored beam was demonstrated. Transverse feedback system makes low chromaticity operation possible; this is very helpful to improve injection efficiency which is essential for routine top-up operation. Operation experiences of the bunch-by-bunch feedback system will be summarized in this report.

Diagnostic and timing supports for top-up injection operation for the TLS

Routine top-up operation of Taiwan light source (TLS) was to commence from October 2005 after high efficiency multi-bunch instabilities suppression system put into service. Long-term 360 mA top-up operation has been tested and proven its successful and steady performance. Short-term 400 mA top-up run is also demonstrated. The TLS is current operated at 300 mA top-up mode to compromise various requirements of users at this moment. Higher current is possible in future. To support the top-up operation, various diagnostics and timing control are needed. These include diagnostics for injection efficiency, filling pattern of the storage ring, tune, instability, loss pattern measurement. Timing control of the injection process is also necessary. Further possible improvement will be also discussed.

Application of the IEEE-1394 and the GigE Vision digital cameras for diagnostics in Taiwan Light Source

Digital camera has been adopted for the booster, storage ring and transport-line diagnostic at the Taiwan Light Source. The system provides low image distortion and lossless image transmission over long distance. The system is integrated with commercial software in the control system. The fully remote control supports to various operations and functional applications. These applications include of screen monitors equipped in the booster and storage ring, wider dynamic range sensors and highly flexibility control for the emittance measurement in the transport line, the booster synchrotron and the linear accelerator. System configuration and present status will be summarized in this report.

Beam trip event diagnostics for the TLS

Analyzing the reasons of various trip events is essential for improvement of system reliability. To identity the causes of trip at Taiwan light source (TLS), various diagnostics tool were employed. These diagnostic tools can capture beam trip, interlock signals of superconducting RF system, waveform of the injection kickers, quench and interlock signals of the superconducting insertion device, and instability signals of the stored beam. These diagnostics can be routine monitor signal and record beam trip event. Features of trip diagnostic tools are available now and future plan will be summarized in this report.