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Barnes, M. J.

Paper Title Page
TUOAC01 Design and Measurements of a Damping Ring Kicker for the ILC 846
 
  • M. J. Barnes
    CERN, Geneva
  • G. D. Wait
    TRIUMF, Vancouver
 
  Funding: Work supported by a contribution from the National Research Council of Canada.

The International Linear Collider (ILC) requires ultra fast kickers for the damping ring. One option requires kickers which must produce pulses of 5 kV magnitude, with 6 ns rise and 6 ns fall time into a 50 Ohm, terminated, matched stripline deflector. The pulse must rise and fall within 12 ns. The pulse magnitude must be repeatable to a high accuracy. This paper describes a novel design for a suitable pulse generator for the damping ring kicker, in which 2 stacks of 1kV FETS are combined to generate the fast pulses. The design concept uses 2 parallel 100 Ω drivers combined to provide a 50 Ω driver. The need for 3 MHz burst mode operation for 1 ms at 5 Hz (or 10 Hz) gives an average rep rate of 15 kHz (or 30 kHz). Measurements and calculations are presented on the present state of the TRIUMF prototype pulse generator.

 
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TUPAN086 An Improved Beam Screen for the LHC Injection Kickers 1574
 
  • M. J. Barnes, F. Caspers, L. Ducimetiere, N. Garrel, T. Kroyer
    CERN, Geneva
 
  The two LHC injection kicker magnet systems must produce a kick of 1.3 T.m with a flattop duration variable up to 7860 ns, and rise and fall times of less than 900 ns and 3000 ns, respectively. Each system is composed of two resonant charging power supplies and four 5 Ω transmission line kicker magnets with matched terminating resistors and pulse forming networks. A beam screen is placed in the aperture of the magnets: the screen consists of a ceramic tube with conductors on the inner wall. The conductors provide a path for the image current of the, high intensity, LHC beam and screen the ferrite against Wake fields. The conductors initially used gave adequately low beam impedance however inter-conductor discharges occurred during pulsing of the magnet: an alternative design was discharge free at the nominal operating voltage but the beam impedance was too high for the ultimate LHC beam. This paper presents the results of a new development undertaken to meet the often conflicting requirements for low beam impedance, shielding of the ferrite, fast field rise time and good electrical behaviour. High voltage test results and thermal measurements are also presented.  
WEPMN068 Design of the Modulator for the CTF3 Tail Clipper Kicker 2185
 
  • M. J. Barnes, T. Fowler, G. Ravida
    CERN, Geneva
  • A. Ueda
    KEK, Ibaraki
 
  The goal of the present CLIC test facility (CTF3) is to demonstrate the technical feasibility of specific key issues in the CLIC scheme. The extracted beam from the combiner ring (CR), of 35 A in magnitude and 140 ns duration, is sent to the new CLic EXperimental area (CLEX) facility. A Tail Clipper (TC) is required, in the CR to CLEX transfer line, to allow the duration of the extracted beam pulse to be adjusted. It is proposed to use a stripline kicker for the tail clipper, with each of the deflector plates driven to equal but opposite potential. The tail clipper kick must have a fast rise-time, of not more than 5 ns, in order to minimize uncontrolled beam loss and operate at a rate of up to 50 Hz. Several different options are being investigated to meet the demanding specifications for the modulator of the tail clipper. This paper discusses options considered for the fast, high voltage, semiconductor switches and shows results of initial tests on the switches.  
WEPMN069 Low Power Measurements on an AGS Injection Kicker Magnet 2188
 
  • M. J. Barnes
    CERN, Geneva
  • G. D. Wait
    TRIUMF, Vancouver
 
  Funding: Work supported by a contribution from the Canada Foundation for Innovation.

The present AGS injection kickers at A5 location were designed for 1.5 GeV proton injection. Recent high intensity runs have pushed the transfer kinetic energy to 1.94 GeV, but with an imperfect matching in transverse phase space. Space charge forces result in both fast and slow beam size growth and beam loss as the size exceeds the AGS aperture. An increase in the AGS injection energy to 2 GeV with adequate kick strength would greatly reduce the beam losses making it possible to increase the intensity from 70 TP (70 * 1012 protons/s) to 100 TP. R&D studies* have been undertaken by TRIUMF, in collaboration with BNL, to design two new kicker magnets for the AGS A10 location to provide an additional kick of 1.5 mrad to 2 GeV protons. TRIUMF has designed and built a prototype 12.5 Ω transmission line kicker magnet with rise and fall times of 100 ns, 3% to 97% and field uniformity of (±)1% over 85% of the aperture, powered by matched 12.5 Ω pulse-forming lines. This paper describes the results of detailed capacitance and inductance measurements, on the prototype magnet, and compares these with predictions from 2D and 3D electromagnetic simulations.

*L. Ahrens, R. B. Armenta, M. J. Barnes, E. W Blackmore, C. J. Gardner, O. Hadary, G. D. Wait, W. Zhang, "Design Concept for AGS Injection Kicker Upgrade to 2 GeV", PAC 2005, Knoxville Tennessee.