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

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

A canonical kick sextupole, which differs from the MULT element with ORDER=2 in that it can be used for chromaticity correction.
Parallel capable? : yes
GPU capable? : yes
Back-tracking capable? : yes


Parameter Name	Units	Type	Default	Description

L	M	double	0.0	length

K2	1∕M³	double	0.0	geometric strength

K1	1∕M²	double	0.0	geometric quadrupole strength error. See notes below!

J1	1∕M²	double	0.0	geometric skew quadrupole strength error. See notes below!

TILT	RAD	double	0.0	rotation about longitudinal axis

PITCH	RAD	double	0.0	rotation about horizontal axis. Ignored if MALIGN_METHOD=0

YAW	RAD	double	0.0	rotation about vertical axis. Ignored if MALIGN_METHOD=0

BORE	M	double	0.0	bore radius

B	T	double	0.0	field at pole tip (used if bore nonzero)

N_KICKS		long	0	number of kicks (rounded up to next multipole of 4 if INTEGRATION_ORDER=4. Deprecated. Use N_SLICES.)

N_SLICES		long	1	Number of slices (full integrator steps).

DX	M	double	0.0	misalignment

DY	M	double	0.0	misalignment

DZ	M	double	0.0	misalignment

FSE		double	0.0	fractional strength error

HKICK	RAD	double	0.0	horizontal correction kick

VKICK	RAD	double	0.0	vertical correction kick

HCALIBRATION		double	1	calibration factor for horizontal correction kick

VCALIBRATION		double	1	calibration factor for vertical correction kick

HSTEERING		short	0	use for horizontal correction?

KSEXT continued

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

VSTEERING		short	0	use for vertical correction?

SYNCH_RAD		short	0	include classical, single-particle synchrotron radiation?

SYSTEMATIC_MULTIPOLES		STRING	NULL	input file for systematic multipoles

EDGE_MULTIPOLES		STRING	NULL	input file for systematic edge multipoles

RANDOM_MULTIPOLES		STRING	NULL	input file for random multipoles

STEERING_MULTIPOLES		STRING	NULL	input file for multipole content of steering kicks

SYSTEMATIC_MULTIPOLE_FACTOR		double	1	Factor by which to multiply systematic and edge multipoles

RANDOM_MULTIPOLE_FACTOR		double	1	Factor by which to multiply random multipoles

STEERING_MULTIPOLE_FACTOR		double	1	Factor by which to multiply steering multipoles

MIN_NORMAL_ORDER		short	-1	If nonnegative, minimum order of systematic and random normal multipoles to use from data files.

MIN_SKEW_ORDER		short	-1	If nonnegative, minimum order of systematic and random skew multipoles to use from data files.

MAX_NORMAL_ORDER		short	-1	If nonnegative, maximum order of systematic and random normal multipoles to use from data files.

MAX_SKEW_ORDER		short	-1	If nonnegative, maximum order of systematic and random skew multipoles to use from data files.

KSEXT continued

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

INTEGRATION_ORDER		short	4	integration order (2, 4, or 6)

SQRT_ORDER		short	0	Ignored, kept for backward compatibility only.

ISR		short	0	include incoherent synchrotron radiation (quantum excitation)?

ISR1PART		short	1	Include ISR for single-particle beam only if ISR=1 and ISR1PART=1

EXPAND_HAMILTONIAN		short	0	If 1, Hamiltonian is expanded to leading order.

MALIGN_METHOD		short	0	0=original, 1=new entrace-centered, 2=new body-centered

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

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.

Multipole errors

Specification of systematic and random multipole errors is supported through the SYSTEMATIC_MULTIPOLES, EDGE_MULTIPOLES, and RANDOM_MULTIPOLES fields. These specify, respectively, fixed multipole strengths for the body of the element, fixed multipole strengths for the edges of the element, and random multipole strengths for the body of the element. 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:

Floating point parameter referenceRadius giving the reference radius for the multipole data.
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.
Floating point columns normal and skew giving the values for the normal and skew multipole strengths, respectively. (N.B.: previous versions used the names an and bn, respectively. This is still accepted but deprecated) These are defined as a fraction of the main field strength measured at the reference radius, R: f_n = , 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 multipole fractional strengths. For random multipoles, the values are interpreted as rms values for the distribution.

Specification of systematic higher multipoles due to steering fields is supported through the STEERING_MULTIPOLES field. This field gives the name of an SDDS file that supplies the multipole data. The file is expected to contain a single page of data with the following elements:

Floating point parameter referenceRadius giving the reference radius for the multipole data.
An integer column named order giving the order of the multipole. The order is defined as (N_poles - 2)∕2. The order must be an even number because of the quadrupole symmetry.
Floating point column normal giving the values for the normal multipole strengths, which are driven by the horizontal steering field. (N.B.: previous versions used the name an for this data. This is still accepted but deprecated) normal is specifies the multipole strength as a fraction f_n of the steering field strength measured at the reference radius, R: f_n = , where m = 0 is the order of the steering field and n is the order of the error multipole. The skew values (for vertical steering) are deduced from the normal values, specifically, g_n = f_n * (-1)^n∕2.

Another way of introducing errors is via the K1 and J1 parameters, which allow introducing a normal and skew quadrupole error term. For tracking, the strength of these values can be arbitrarily high without introducing errors. However, the matrix analysis (e.g., for determination of tunes and beta functions) assumes that these are weak effects and high accuracy should not be expected if this is not true. If K1 is significant, then use of the KQUSE element is preferred.

Apertures

Apertures specified via an upstream MAXAMP element or an aperture_input command will be imposed inside this element.

Misalignments

There are three modes for implementing alignment errors. Which is used is controlled by the value of the MALIGN_METHOD parameter:

MALIGN_METHOD=0 — This selects the original method, which was the only one available before version 2021.1. The misalignment is referenced to the entrance face. The YAW and PITCH parameters are ignored.
MALIGN_METHOD=1 — This selects a linearized method based on M. Venturini’s work [58], with misalignment referenced to the entrance face. The YAW and PITCH parameters are implemented.
MALIGN_METHOD=2 — This selects a linearized method based on M. Venturini’s work [58], with misalignment referenced to the magnet center. The YAW and PITCH parameters are implemented.
MALIGN_METHOD=3 — This selects an exact method based on M. Venturini’s work [58], with misalignment referenced to the entrance face. The YAW and PITCH parameters are implemented.
MALIGN_METHOD=4 — This selects an exact method based on M. Venturini’s work [58], with misalignment referenced to the magnet center. The YAW and PITCH parameters are implemented.

For elements with non-zero TILT, error displacements and rotations are performed in the lab frame.

LGBEND

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