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Di Monte, N. P.

Paper Title Page
MOPAN113 The P0 Feedback Control System Blurs the Line between IOC and FPGA 431
 
  • N. P. Di Monte
    ANL, Argonne, Illinois
  
  Funding: Work supported by U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.

The P0 Feedback System is a new design at the APS with the main intent to stabilize a single bunch in order to operate at a higher accumulated charge. The algorithm for this project required a high-speed DSP solution for a single channel that would make adjustments on a turn-by-turn basis. An FPGA solution was selected that not only met the requirements of the project, but far exceeded the requirements. By using a single FPGA, we were able to adjust up to 324 bunches on two separate channels with a total computational time of ~6x109 multiply-accumulate operations per second. The IOC is a Coldfire CPU tightly coupled to the FPGA, providing a dedicated control and monitoring of the system through EPICS process variables. One of the benefits of this configuration is having a four-channel scope in the FPGA that can be monitored on a continuous basis.

 
MOPAN116 An FPGA-Based Bunch-to-Bunch Feedback System at the Advanced Photon Source 440
 
  • C. Yao, N. P. Di Monte, W. E. Norum
    ANL, Argonne, Illinois
  
  Funding: Work supported by U. S. Department of Energy, Office of Basic Energy Sciences, under Contract No. W-31-109-ENG-38.

The Advanced Photon Source storage ring has several bunch fill patterns for user operation. The hybrids fill pattern consists of a single bunch with a charge of 16 mA and a bunch train of 56 bunches. Both horizontal and vertical instabilities are observed. Currently chromaticity correction is the only method available to overcome the instability. Beamlife time and injection efficiency suffer because of high sextupole currents. A bunch-to-bunch feedback system is designed to overcome beam instability and reduce the required chromaticity correction. The feedback system is based on an FPGA DSP processor. The signal filtering algorithm is based on the time-domain-least-square method developed at SPring-8. We have just completed the integration of the system. We report the system design and some test results.

 
WEPMN085 The Advanced Photon Source Pulsed Deflecting Cavity RF System 2224
 
  • A. E. Grelick, A. R. Cours, N. P. Di Monte, A. Nassiri, T. Smith, G. J. Waldschmidt
    ANL, Argonne, Illinois
  
  Funding: Work supported by the U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.

The Phase I Advanced Photon Source Deflecting Cavity System for producing short X-ray pulses uses one multi-cell, S-band cavity to apply a deflecting voltage to the stored electron beam ahead of an undulator that supports a beamline utilizing short picosecond X-rays. Two additional multi-cell cavities are then used to cancel out the perturbation and redirect the electron beam along the path of its nominal orbit. The pulsed rf system driving the deflecting cavities is described. Design tradeoffs are discussed with emphasis on topology considerations and digital control loops making use of sampling technology in a manner consistent with the present state of the art.