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Hoffstaetter, G.

Paper Title Page
MOPKF077 Reducing the Synchrotron Radiation on RF Cavity Surfaces in an Energy-recovery Linac 494
 
  • G. Hoffstaetter, M. Liepe, T. Tanabe
    Cornell University, Laboratory for Elementary-Particle Physics, Ithaca, New York
  
  In Energy Recovery Linac (ERL) light sources, a high energy, high current beam has to be bend into a superconducting linac to be decelerated. The synchrotron radiation produced in the last bending magnet before the linac shines into the superconducting structures if not collimated appropriately. Due to the length of the linac, the radiation cannot be completely guided through the superconducting structure, as in existing SRF storage rings. For the example of an ERL extension to the existing CESR storage ring at Cornell we estimate the magnitude of this problem by quantifying the heat load that can be accepted on a superconducting surface and by analyzing how much radiation is deposited on the cavity surfaces for different collimation schemes.  
MOPKF078 ERL Upgrade of an Existing X-ray Facility: CHESS at CESR 497
 
  • G. Hoffstaetter, M. Liepe, R.M. Talman, M. Tigner
    Cornell University, Laboratory for Elementary-Particle Physics, Ithaca, New York
  • I. Bazarov, H. Bilderback, M. Billing, S. Gruner, D. Sagan, C.K. Sinclair
    Cornell University, Department of Physics, Ithaca, New York
  
  CORNELL has proposed an Energy-Recovery Linac (ERL) based synchrotron-light facility which can provide improved x-ray radiation due to the high beam quality that can be available from a linac. To additionally utilize beam currents that are competitive with ring-based light sources, the linac has to operate with the novel technique of energy recovery, the feasibility of which CORNELL plans to demonstrate in a downscaled prototype ERL. Here we present an ERL upgrade of the existing 2nd generation light source CHESS at CESR. This proposed upgrade suggests how existing storage rings can be extended to ERL light sources with much improved beam qualities.  
WEPLT153 Multi-pass Beam-breakup: Theory and Calculation 2194
 
  • I. Bazarov
    Cornell University, Department of Physics, Ithaca, New York
  • G. Hoffstaetter
    Cornell University, Laboratory for Elementary-Particle Physics, Ithaca, New York
  
  Multi-pass, multi-bunch beam-breakup (BBU) has been long known to be a potential limiting factor for the current in linac-based recirculating accelerators. New understanding of theoretical and computational aspects of the phenomenon are presented here. We also describe a detailed simulation study of BBU in the proposed 5 GeV Energy Recovery Linac light source at Cornell University which is presented in a separate contribution to this conference.  
THPLT150 Results from Orbit and Optics Improvement by Evaluating the Nonlinear Beam Position Monitor Response in CESR 2804
 
  • R.W. Helms, G. Hoffstaetter
    Cornell University, Laboratory for Elementary-Particle Physics, Ithaca, New York
  
  In the Cornell Electron/positron Storage Ring (CESR), pretzel orbits with large horizontal oscillations are used to keep electron and positron beams out of collision except at the interaction point. Since a beam position monitor's (BPM's) response is only linear near the center of the beam pipe, the assumption of linearity does not allow for accurate orbit and phase measurements under colliding beam conditions. Using a numerical model of the BPMs' response to large offsets of the beam position, and an enhanced algorithm for real-time inversion of this nonlinear response function, we have extended our orbit and betatron phase measurements to beams with large pretzel amplitudes. Several measurements demonstrate the applicability, accuracy, and usefulness of this method.  
THPLT151 Evaluation of Beam Position Monitors in the Nonlinear Regime 2807
 
  • R.W. Helms, G. Hoffstaetter
    Cornell University, Laboratory for Elementary-Particle Physics, Ithaca, New York
  
  Here we present a new algorithm for processing BPM signals and extracting orbit and phase data for very large beam excursion where the BPM response function changes nonlinearly with the beam position. Using two dimensional models of each BPM geometry, we calculate the button response using numerical solution of Laplace's equation and Green's reciprocity theorem. The difference between the calculated signals and the measured signals is minimized in real time to calculate the beam position and measurement errors. Using the derivatives of the response functions, we model the effect of beam shaking, and from it, calculate the betatron phase.