KSEXT

A canonical kick sextupole, which differs from the MULT element with ORDER=2 in that it can be used for chromaticity correction.

Parameter Name	Units	Type	Default	Description
L	$M$	double	0.0	length
K2	$1/M^{3}$	double	0.0	geometric strength
TILT	$RAD$	double	0.0	rotation about longitudinal axis
BORE	$M$	double	0.0	bore radius
B	$T$	double	0.0	field at pole tip (used if bore nonzero)
DX	$M$	double	0.0	misalignment
DY	$M$	double	0.0	misalignment
DZ	$M$	double	0.0	misalignment
FSE	$M$	double	0.0	fractional strength error
N_KICKS		long	4	number of kicks
SYNCH_RAD		long	0	include classical synchrotron radiation?
SYSTEMATIC_MULTIPOLES		STRING	NULL	input file for systematic multipoles
RANDOM_MULTIPOLES		STRING	NULL	input file for random multipoles
INTEGRATION_ORDER		long	4	integration order (2 or 4)
SQRT_ORDER		long	0	Order of expansion of square-root in Hamiltonian. 0 means no expansion.

This element simulates a sextupole using a kick method based on symplectic integration. The user specifies the number of kicks and the order of the integration. For computation of twiss parameters, chromaticities, and response matrices, this element is treated like a standard thick-lens sextuupole; i.e., the number of kicks and the integration order become irrelevant.

Specification of systematic and random multipole errors is supported through the SYSTEMATIC_MULTIPOLES and RANDOM_MULTIPOLES fields. These fields give the names of SDDS files that supply the multipole data. The files are expected to contain a single page of data with the following elements:

1. Floating point parameter referenceRadius giving the reference radius for the multipole data.
2. An integer column named order giving the order of the multipole. The order is defined as $(N_{poles}-2)/2$, so a quadrupole has order 1, a sextupole has order 2, and so on.
3. Floating point columns an and bn giving the values for the normal and skew multipole strengths, respectively. These are defined as a fraction of the main field strength measured at the reference radius, R: $a_n = \frac{K_n r^n / n!}{K_m r^m / m!}$, where $m=2$ is the order of the main field and $n$ is the order of the error multipole. A similar relationship holds for the skew multipoles. For random multipoles, the values are interpreted as rms values for the distribution.