This is the line description of quadrupoles available in TRACK.
1D Quadrupole
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n quad Bf phy_len eff_len rap nstep
n : Quadrupole type;
n = 0: Internal TRACK Quadrupole models
If eff_len = phy_len --> Hard-Edge Model.
If nstep=0, a transfer matrix is used without SC calculation.
If nstep>0, a uniform field is used for integration with SC.
If eff_len < phy_len --> Fringe-Field Model.
If nstep=0, iint in "track.dat" is used nstep=iint.
If nstep>0, nstep is used as an integration step.
The internal fringe field model uses Enge coefficients for the
fall-off of edge fields.
The parameters of the model (Enge coefficients) can be adjusted
using the "enge" element in "sclinac.dat" file just before the
"quad" line. If not specified, the internal default Enge
coefficients will be used for both the entrance and exit of the
quadrupole.
To input your own values of Enge coefficients, insert these
two lines before the "quad" line in "sclinac.dat":
1 enge quad EC1 EC2 EC3 EC4 EC5 EC6
2 enge quad EC1 EC2 EC3 EC4 EC5 EC6
Where "1" is for the quadrupole entrance and "2" is for the
quadrupole exit. EC1-6 are the new values for the 6 Enge
coefficients to be used instead of the default internal values
given in the line below:
1 enge quad -0.00004 4.518219 0. 0. 0. 0.
If only one "enge" line is entered it will be used for both the
entrance and exit of the quadrupole.
n > 0: Quadrupole with External 1D field profile.
This option is not yet available, it is treated as n=0.
Bf [G]: Field strength at the aperture: Gradient = Bf/Rap.
Bf > 0 provides focusing in the horizontal plane.
len [cm]: Element/Field length
eff_len [cm]: Effective length
rap [cm]: Aperture radius
nstep : (optional) Number of integration steps.
For n=0 and eff_len=phy_len (-> Hard-Edge Model), nstep should be
non 0 to include space charge effects with integration. If nstep=0
or not specified, a transfer matrix is used without SC calculation.
1/2 Quadrupole
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n quad Bf phy_len eff_len rap iquad nstep
All other parameters are the same as the full quadrupole above.
The new parameter is "iquad" inserted before "nstep"
iquad : First (upstream) or Second (downstream) half of a quadrupole
iquad = 1, first half
iquad = 2, second half
3D Quadrupole
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n qua3d Bf len rap nstep
n : Quadrupole Type; it is also the external EMS field file number
eh_EMS.#nn which sould exist.
Bf [G]: Field strength
len [cm]: Solenoid/Field length
rap [cm]: Aperture radius
nstep : (optional) Number of integration steps.