10.77 RBEN—A rectangular dipole, implemented as a SBEND with edge angles, up to 2nd order. Use CSBEND for symplectic tracking.

A rectangular dipole, implemented as a SBEND with edge angles, up to 2nd order. Use CSBEND for symplectic tracking.
Parallel capable? : yes
GPU capable? : yes
Back-tracking capable? : yes






Parameter Name UnitsType Default

Description






L M double0.0

magnet (straight) length






ANGLE RADdouble0.0

bend angle






K1 1∕M2double0.0

geometric focusing strength






E1 RADdouble0.0

entrance edge angle






E2 RADdouble0.0

exit edge angle






TILT RADdouble0.0

rotation about incoming longitudinal axis






K2 1∕M3double0.0

geometric sextupole strength






H1 1∕M double0.0

entrance pole-face curvature






H2 1∕M double0.0

exit pole-face curvature






HGAP M double0.0

half-gap between poles






FINT double0.5

edge-field integral






DX M double0.0

misaligment of entrance






DY M double0.0

misalignment of entrance






DZ M double0.0

misalignment of entrance






FSE double0.0

fractional strength error of all components






FSE_DIPOLE double0.0

fractional strength error of dipole component






FSE_QUADRUPOLE double0.0

fractional strength error of quadrupole component






ETILT RADdouble0.0

error rotation about incoming longitudinal axis






ETILT_SIGN short 1

Sign of ETILT relative to TILT. -1 is the old convention prior to 2020.5






EDGE1_EFFECTS short 1

include entrance edge effects?






EDGE2_EFFECTS short 1

include exit edge effects?






ORDER short 0

matrix order






EDGE_ORDER short 0

edge matrix order






TRANSPORT short 0

use (incorrect) TRANSPORT equations for T436 of edge?






USE_BN short 0

use B1 and B2 instead of K1 and K2 values?






RBEN continued

A rectangular dipole, implemented as a SBEND with edge angles, up to 2nd order. Use CSBEND for symplectic tracking.






Parameter NameUnitsType Default

Description






B1 1∕M double0.0

K1 = B1/rho, where rho is bend radius






B2 1∕M2double0.0

K2 = B2/rho






GROUP string NULL

Optionally used to assign an element to a group, with a user-defined name. Group names will appear in the parameter output file in the column ElementGroup






When adding errors, care should be taken to choose the right parameters. The FSE and ETILT parameters are used for assigning errors to the strength and alignment relative to the ideal values given by ANGLE and TILT. One can also assign errors to ANGLE and TILT, but this has a different meaning: in this case, one is assigning errors to the survey itself. The reference beam path changes, so there is no orbit/trajectory error. The most common thing is to assign errors to FSE and ETILT. Note that when adding errors to FSE, the error is assumed to come from the power supply, which means that multipole strengths also change.

Special note about splitting dipoles: when dipoles are long, it is common to want to split them into several pieces, to get a better look at the interior optics. When doing this, care must be exercised not to change the optics. elegant has some special features that are designed to reduce or manage potential problems. At issue is the need to turn off edge effects between the portions of the same dipole.

First, one can simply use the divide_elements command to set up the splitting. Using this command, elegant takes care of everything.

Second, one can use a series of dipoles with the same name. In this case, elegant automatically turns off interior edge effects. This is true when the dipole elements directly follow one another or are separated by a MARK element.

Third, one can use a series of dipoles with different names. In this case, you must also use the EDGE1_EFFECTS and EDGE2_EFFECTS parameters to turn off interior edge effects.

RCOL