07 Accelerator Technology

T23 Timing and Synchronization

Paper Title Page
MOOCRA03 Femtosecond Synchronization of Laser Systems for the LCLS 58
 
  • J.M. Byrd, L.R. Doolittle, G. Huang, J.W. Staples, R.B. Wilcox
    LBNL, Berkeley, California
  • J. Arthur, J.C. Frisch, W.E. White
    SLAC, Menlo Park, California
 
 

The scientific potential of femtosecond x-ray pulses at linac-driven FELs such as the LCLS is tremendous. Time-resolved pump-probe experiments require a measure of the relative arrival time of each x-ray pulse with respect to the experimental pump laser. In order to achieve this, precise synchronization is required between the arrival time diagnostic and the laser which are often separated by hundreds of meters. We describe an optical timing system based on stabilized fiber links which has been developed for the LCLS to provide this synchronization. Preliminary results show stability of the timing distribution at the sub-10 fsec level and overall synchronization of the x-rays and pump laser of less than 40 fsec. We present details of the implementation and LCLS and potential for future development.

 

slides icon

Slides

 
TUPEA029 Synchronized Clock System for Acceleration Pattern Generation and its Beam Tests in HIMAC Synchrotron 1387
 
  • M. Kanazawa, Y. Iwata
    NIRS, Chiba-shi
  • T. Fujimoto
    AEC, Chiba
  • K. Watanabe
    Toshiba Medical Systems Corporation, Tochigi
 
 

In the routine operation of HIMAC synchrotron, a pulse system of field change with 0.2 Gauss in the monitor dipole magnet (B-clock) is used to generate pattern data in the acceleration system. To eliminate error pulse due to noise in analogue field signal, a clock system locked to a 1.2kHz clock for a power supplies was developed, which can be used to generate pattern data of an acceleration system with maximum frequency of 192kHz. This 1.2kHz clock is synchronized to a power line frequency of 50Hz that will fluctuate about 0.1%, so the clock of 192kHz must also follow this frequency fluctuation. To demonstrate the performance of new clock system, we have tested beam acceleration, and compared with the conventional B-clock system. Acceleration efficiencies were checked with changing these clock rates in the both systems. With these tests, we have found that the relatively low clock rate in the newly developed system is enough to get good acceleration performance. In this paper the clock system, and their beam tests will be presented.

 
TUPEA030 Transmission of Reference RF Signals Through Optical Fiber at XFEL/SPring-8 1390
 
  • T. Ohshima, N. Hosoda, H. Maesaka, S. Matsubara, Y. Otake
    RIKEN/SPring-8, Hyogo
 
 

The pulse width of an X-ray laser at XFEL/SPring-8 is several tens femto-seconds, which requires reference rf signals to have the same time-stability. The reference signals with a low phase-noise oscillator are sent to instruments in 19" racks developed along an accelerator by an optical fiber system. The temperature drift of the fiber makes phase shifts of the reference signals. Therefore, the fiber is put in a thermal-insulated duct. By feeding temperature-controlled water (26.1 ± 0.1 deg. C) in a pipe attached to the duct, the fiber temperature was kept to be 26.2 ± 0.08 deg. C at the ambient temperature change of 29.1 ± 1.7 deg. C. From this temperature controllability, the phase shifts of the signals through a 400 m fiber of a thermal coefficient of 5 ps/km/K are 160 fs. Further reduction of the shifts is required and will be achieved by a fiber-length feedback control in a future plan. Vibration of the fiber also degrades the quality of the signals. The fiber is embedded on a vibration buffer material. A test to evaluate the effect of the vibration to the transmitted signal phase was carried out. The test result will be also shown in this paper.

 
TUPEA031 Synchronization and Control System for Tsinghua Thomson Scattering X-ray Source 1393
 
  • D. Qiang, Y.-C. Du, W.-H. Huang, C.-X. Tang, L.X. Yan
    TUB, Beijing
 
 

The Tsinghua Thomson scattering X-ray source (TTX) has a strict laser-electron synchronization requirement and a comprehensive system structure including dual high-power laser system, RF system and beam diagnostic instruments, etc. Recently, a synchronization and control system is developed to meet these requirements, which includes a laser-RF synchronizer with 100fs time jitter, a FPGA based event generator for laser and RF systems with 250ps time resolution, and an EPICS based control system for system integration and remote monitor and control. The electron bunch arrival time jitter is carefully measured and analyzed with the help of a RF deflecting cavity. This paper reports the development status, technical implementation, and measurement results of the synchronization and control system.

 
TUPEA032 A New Timing System: the Real-time Synchronized Data Bus 1396
 
  • M. Liu, D.K. Liu, C.X. Yin, L.Y. Zhao
    SINAP, Shanghai
 
 

Currently, the real-time data transfer system is widely implemented in the accelerator control system. If timing system and real-time data transfer system could be combined into one uniform system, it would be convenient to build distributed feedback system, fast interlock system and so on. So, a new timing system, the real-time synchronized data bus is developed to realize this idea. The architecture of the system and the hardware prototype design are introduced in the paper. The data exchange mechanism and system specification, including timing trigger synchronization accuracy, timing jitter relative to RF clock, data transfer rate and latency are described in detail. Redundant topology structure and fiber length compensation are specially considered. In the end, the results of testing in lab are presented.

 
TUPEA033 Stable Transmission of RF Signals on Optical Fiber Links 1399
 
  • J.M. Byrd, L.R. Doolittle, G. Huang, J.W. Staples, R.B. Wilcox
    LBNL, Berkeley, California
 
 

Stabilized optical fiber links have been under development for several years for high precision transmission of timing signals for remote synchronization of accelerator and laser systems. In our approach, a master clock signal is modulated on an optical carrier over a fiber link. The optical carrier is also used as the reference in a heterodyne interferometer which is used to precisely measure variations, mainly thermal, in the fiber length. The measured variations are used to correct the phase of the transmitted clock signal. We present experimental results showing sub-10 fsec relative stability of a 200 m link a sub-20 fsec stability of a 2.2 km link.