Author: Farnsworth, R.I.
Paper Title Page
TUOAB01 Timing and Synchronization for the APS Short Pulse X-ray Project 1077
  • F. Lenkszus, N.D. Arnold, T.G. Berenc, G. Decker, E.M. Dufresne, R.I. Farnsworth, Y.L. Li, R.M. Lill, H. Ma
    ANL, Argonne, USA
  • J.M. Byrd, L.R. Doolittle, G. Huang, R.B. Wilcox
    LBNL, Berkeley, California, USA
  Funding: Work supported by U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
The Short-Pulse X-ray (SPX) project, which is part of the APS upgrade, will provide intense, tunable, high-repetition-rate picosecond x-ray pulses through the use of deflecting cavities operating at the 8th harmonic of the storage-ring rf. Achieving this picosecond capability while minimizing the impact to other beamlines outside the SPX zone imposes demanding timing and synchronization requirements. For example, the mismatch between the upstream and downstream deflecting cavities' rf field phase is specified to be less than 0.077 degrees root mean squared (rms) at 2815 MHz (~77 femtoseconds). Another stringent requirement is to synchronize beamline pump-probe lasers to the SPX x-ray pulse to 400 femtoseconds rms. To achieve these requirements we have entered into a collaboration with the Beam Technology group at LBNL. They have developed and demonstrated a system for distributing stable rf signals over optical fiber capable of achieving less than 20 femtoseconds rms drift and jitter over 2.2 km over 60 hours*. This paper defines the overall timing/synchronization requirements for the SPX and describes the plan to achieve them.
* R. Wilcox et al. Opt. Let. 34(20), Oct 15, 2009
slides icon Slides TUOAB01 [2.515 MB]  
WEPPP069 Performance Enhancements for the Transverse Feedback System at the Advanced Photon Source 2867
  • N.P. Di Monte, R.I. Farnsworth, A.J. Scaminaci
    ANL, Argonne, USA
  With the success of the transverse feedback system at the Advanced Photon Source (APS), an upgrade to this system is being developed. The current system is operating at a third of the storage ring bunch capacity, or 324 of the available 1296 bunches. This upgrade will allow the sampling of all 1296 bunches and make corrections for all selected bunches in a single storage ring turn. To facilitate this upgrade, a new analog I/O board capable of 352-MHz operation is being developed along with a P0 bunch cleaning circuit. The clock cleaning circuit is also needed for the high speed analog output circuit, which is transmitted about 200 m to a separate DAC unit in real time. This remote DAC will have its transceiver data rate triple from 2.3 Gb to about 7 Gb on a fiber optic link. This paper will discuss some of the challenges in reducing the clock jitter from the system P0 bunch clock along with the necessary FPGA hardware upgrades and algorithm changes, all of which are required for the success of this upgrade.  
WEPPP070 Simulation of the APS Storage Ring Orbit Real-Time Feedback System Upgrade Using MATLAB 2870
  • S. Xu, G. Decker, R.I. Farnsworth, F. Lenkszus, H. Shang, X. Sun
    ANL, Argonne, USA
  Funding: Work supported by U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
The Advanced Photon Source (APS) storage ring orbit real-time feedback (RTFB) system plays an important role in stabilizing the orbit of the stored beam. An upgrade is planned that will improve beam stability by increasing the correction bandwidth to 200 Hz or higher. To achieve this, the number of available steering correctors and beam position monitors (BPMs) will be increased, and the sample rate will be increased by an order of magnitude. An additional benefit will be the replacement of aging components. Simulations have been performed to quantify the effects of different system configurations on performance.