A   B   C   D   E   F   G   H   I   J   K   L   M   N   O   P   Q   R   S   T   U   V   W   X   Y   Z  

Eddy, N. E.

Paper Title Page
MOPAS011 Uniform Longitudinal Beam Profiles in the Fermilab Recycler Using Adaptive RF Correction 458
  • M. Hu, D. R. Broemmelsiek, B. Chase, J. L. Crisp, N. E. Eddy, P. W. Joireman, K. Y. Ng
    Fermilab, Batavia, Illinois
  Non-uniformity in longitudinal beam profiles due to potential well distortion have been observed in the Fermilab Recycler Ring. The main source of distortion, the analysis, and the experimental verification of a solution are presented. An adaptive algorithm has been developed to remove the distortion. This algorithm has been implemented in a custom FPGA-based module, which has been integrated into the current Low Level RF system.  
THOAC03 Measurement of the Beam's Trajectory Using the Higher Order Modes it Generates in a Superconducting Accelerating Cavity 2642
  • S. Molloy, J. C. Frisch, J. May, D. J. McCormick, M. C. Ross, T. J. Smith
    SLAC, Menlo Park, California
  • N. Baboi, O. Hensler, R. Paparella, L. M. Petrosyan
    DESY, Hamburg
  • N. E. Eddy, L. Piccoli, R. Rechenmacher, M. Wendt
    Fermilab, Batavia, Illinois
  • O. Napoly, C. Simon
    CEA, Gif-sur-Yvette
  Funding: US DOE Contract #DE-AC02-76SF00515

It is well known that an electron beam excites Higher Order Modes (HOMs) as it passes through an accelerating cavity~[panofsky68]. The properties of the excited signal depend not only on the cavity geometry, but on the charge and trajectory of the beam. It is, therefore, possible to use these signals as a monitor of the beam's position. Electronics were installed on all forty cavities present in the FLASH~[flashref] linac in DESY. These electronics filter out a mode known to have a strong dependence on the beam's position, and mix this down to a frequency suitable for digitisation. An analysis technique based on Singular Value Decomposition (SVD) was developed to calculate the beam's trajectory from the output of the electronics. The entire system has been integrated into the FLASH control system.

slides icon Slides  
THPMS049 Investigations of the Wideband Spectrum of Higher Order Modes Measured on TESLA-style Cavities at the FLASH Linac 3100
  • S. Molloy, C. Adolphsen, K. L.F. Bane, J. C. Frisch, Z. Li, J. May, D. J. McCormick, T. J. Smith
    SLAC, Menlo Park, California
  • N. Baboi
    DESY, Hamburg
  • N. E. Eddy, L. Piccoli, R. Rechenmacher
    Fermilab, Batavia, Illinois
  • R. M. Jones
    UMAN, Manchester
  Funding: US DOE Contract #DE-AC02-76SF00515

Higher Order Modes (HOMs) excited by the passage of the beam through an accelerating cavity depend on the properties of both the cavity and the beam. It is possible, therefore, to draw conclusions on the inner geometry of the cavities based on observations of the properties of the HOM spectrum. A data acquisition system based on two 20 GS/s, 6 GHz scopes has been set up at the FLASH facility, DESY, in order to measure a significant fraction of the HOM spectrum predicted to be generated by the TESLA cavities used for the acceleration of its beam. The HOMs from a particular cavity at FLASH were measured under a range of known beam conditions. The dipole modes have been identified in the data. 3D simulations of different manufacturing errors have been made, and it has been shown that these simulations can predict the measured modes.