Author: Day, H.A.
Paper Title Page
MOPS078 Coaxial Wire Measurements of Ferrite Kicker Magnets 784
 
  • H.A. Day, R.M. Jones
    UMAN, Manchester, United Kingdom
  • M.J. Barnes, F. Caspers, H.A. Day, E. Métral, B. Salvant, C. Zannini
    CERN, Geneva, Switzerland
 
  Fast kicker magnets are used to inject beam into and eject beam out of the CERN accelerator rings. These kickers are generally transmission line type magnets with a rectangular shaped aperture through which the beam passes. Unless special precautions are taken the impedance of the yoke can provoke significant beam induced heating, especially for high intensities. In addition the impedance may contribute to beam instabilities. The results of longitudinal and transverse impedance measurements, for various kicker magnets, are presented and compared with analytical calculations: in addition predictions from a numerical analysis are discussed.  
 
MOPS079 Simulations of Coaxial Wire Measurements of the Impedance of Asymmetric Structures 787
 
  • H.A. Day, R.M. Jones
    UMAN, Manchester, United Kingdom
  • F. Caspers, H.A. Day, E. Métral
    CERN, Geneva, Switzerland
 
  Coaxial wire measurements have provided a simple and effective way to measure the beam coupling impedance of accelerator structures for a number of years. It has been known how to measure the longitudinal and dipolar transverse impedance using one and two wires for some time. Recently the ability to measure the quadrupolar impedance of structures exhibiting top/bottom and left/right symmetry has been demonstrated. A method for measuring the beam coupling impedance of asymmetric structures using displaced single wires and two wire measurements is proposed. Simulations of the measurement system are presented with further work proposed.  
 
MOPS080 Comparison of the Current LHC Collimators and the SLAC Phase 2 Collimator Impedances 790
 
  • H.A. Day, R.M. Jones
    UMAN, Manchester, United Kingdom
  • F. Caspers, H.A. Day, E. Métral, B. Salvant
    CERN, Geneva, Switzerland
 
  One of the key sources of transverse impedance in the LHC has been the secondary graphite collimators that sit close to the beam at all energies. This limits the stable bunch intensity due to transverse coupled-bunch instabilities and transverse mode coupling instability. To counteract this, new secondary collimators have been proposed for the phase II upgrade of the LHC collimation system. A number of designs based on different jaw materials and mechanical designs have been proposed. A comparison of the beam coupling impedance of these different designs derived from simulations are presented, with reference to the existing phase I secondary collimator design.  
 
MOPS079 Simulations of Coaxial Wire Measurements of the Impedance of Asymmetric Structures 787
 
  • H.A. Day, R.M. Jones
    UMAN, Manchester, United Kingdom
  • F. Caspers, H.A. Day, E. Métral
    CERN, Geneva, Switzerland
 
  Coaxial wire measurements have provided a simple and effective way to measure the beam coupling impedance of accelerator structures for a number of years. It has been known how to measure the longitudinal and dipolar transverse impedance using one and two wires for some time. Recently the ability to measure the quadrupolar impedance of structures exhibiting top/bottom and left/right symmetry has been demonstrated. A method for measuring the beam coupling impedance of asymmetric structures using displaced single wires and two wire measurements is proposed. Simulations of the measurement system are presented with further work proposed.  
 
MOPS080 Comparison of the Current LHC Collimators and the SLAC Phase 2 Collimator Impedances 790
 
  • H.A. Day, R.M. Jones
    UMAN, Manchester, United Kingdom
  • F. Caspers, H.A. Day, E. Métral, B. Salvant
    CERN, Geneva, Switzerland
 
  One of the key sources of transverse impedance in the LHC has been the secondary graphite collimators that sit close to the beam at all energies. This limits the stable bunch intensity due to transverse coupled-bunch instabilities and transverse mode coupling instability. To counteract this, new secondary collimators have been proposed for the phase II upgrade of the LHC collimation system. A number of designs based on different jaw materials and mechanical designs have been proposed. A comparison of the beam coupling impedance of these different designs derived from simulations are presented, with reference to the existing phase I secondary collimator design.