Elements/SEXT

SEXT †

A sextupole magnet.

DISFRIN: If nonzero, the nonlinear maxwellian fringe is suppressed. The effects of DISFRIN and FRINGE are summarized as

                   DISFRIN=0                   DISFRIN<>0
             Nonlinear      Linear       Nonlinear     Linear
FRINGE=0    entr & exit      none          none         none
FRINGE=1       entr          entr          none         entr
FRINGE=2       exit          exit          none         exit
FRINGE=3    entr & exit   entr & exit      none      entr & exit

DISRAD: If nonzero, the synchrotron radiation in the particle-tracking is inhibited.
DX: Horizontal displacement of magnet. This applied before the rotation by ROTATE.
DY: Vertical displacement of magnet. This applied before the rotation by ROTATE.

K2: The normal 6-pole magnetic field component (times the length L).
where L is the length of the component. Positive sign means horizontal focusing.

L: Effective length.
ROTATE: Rotation in x-y plane. After displacing the magnet by DX and DY, rotate the magnet around the local s-axis by -(amount given by ROTATE), then place the component. At the exit rotate back the magnet around the local s-axis at the exit, then take out displacement.

transformation: The transformation in a SEXT is given as
where L and H2 are Hamiltonians of a drift of length L and a thin sextupole kick of integrated strength K2:

respectively. The coeffients are a math image and . Terms and are transformations for entrance and exit nonlinear fringes. The term is a correction to adjust the third-order terms in L:

  V2 = (SUM over j=(x,y), k=(x,y)) [
             - beta/2 (H2,k)^2 
             + gamma (H2,j H2,k H2,j,k)] ,

where ,i represents the derivertive by x or y. We have also introduces two coefficients a math image and .

SEXT †

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