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Stray field reduction of ALS eddy current septum magnets

  • Author(s): Shuman, D
  • Barry, W
  • Prestemon, S
  • Schlueter, R
  • Steier, C
  • Stover, G
  • et al.
Abstract

Stray field from an eddy current septum magnet adversely affects the circulating beam and can be reduced using several techniques. The stray field time history typically has a fast rise section followed by a long exponential decay section when pulsed with a half sine drive current. Changing the drive current pulse to a full sine has the effect of both reducing peak stray field magnitude by ∼ 3x and producing a quick decay from this peak to a lower field level which then has a similar long decay time constant as that from the half sine drive current pulse. A method for tuning the second half-sine (reverse) current pulse to eliminate the long exponential decay section is given. A method for halving the remaining brief peak is also given. © 2005 IEEE.

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