CWIGGLER

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CWIGGLER

Tracks through a wiggler using canonical integration routines of Y. Wu (Duke University).
Parallel capable? : yes

Parameter Name	Units	Type	Default	Description
L		double	0.0	Total length
BMAX		double	0.0	Maximum magnetic field.
DX		double	0.0	Misaligment.
DY		double	0.0	Misaligment.
DZ		double	0.0	Misaligment.
TILT		double	0.0	Rotation about beam axis.
PERIODS		long	`0`	Number of wiggler periods.
STEPS_PER_PERIOD		long	10	Integration steps per period.
INTEGRATION_ORDER		long	4	Integration order (2 or 4).
BY_FILE		STRING	NULL	Name of SDDS file with By harmonic data.
BX_FILE		STRING	NULL	Name of SDDS file with Bx harmonic data.

This element simulates a wiggler or undulator using Ying Wu's canonical integration code for wigglers. To use the element, one must supply an SDDS file giving harmonic analysis of the wiggler field. The field expansion used by the code for a horizontally-deflecting wiggler is (Y. Wu, Duke University, private communication).

$\begin{displaymath} B_y = -\left\vert B_0\right\vert \sum_{m,n} C_{mn}\cos(k_{xl} x) \cosh (k_{ym} y) \cos(k_{zn} z + \theta_{zn}), \end{displaymath}$

(3)

where $\left\vert B_0\right\vert$ is the peak value of the on-axis magnetic field, the $C_{mn}$ give the relative amplitudes of the harmonics, the wavenumbers statisfy $k^2_{ym} = k^2_{xl} + k^2_{zn}$ , and $\theta_{zn}$ is the phase.

The file must contain the following columns:

The harmonic amplitude, $C_{mn}$ , in column Cmn.
The phase, in radians, in column Phase. The phase of the first harmonic should be 0 or $\pi$ in order to have matched dispersion.
The three wave numbers, normalized to $k_w = 2\pi/\lambda_w$ , where $\lambda_w$ is the wiggler period. These are given in columns KxOverKw, KyOverKw, and KzOverKw.

For matrix and radiation integral computations, elegant uses a WIGGLER element when it encounters a CWIGGLER. The effective bending radius is $B\rho/B_0/\sqrt{\sum C_{mn}^2}$ (L. Emery, private communication). Tests show that this gives good agreement in the tunes from tracking and Twiss parameter calculations.

Next: DRIF Up: Element Dictionary Previous: CSRDRIFT

Robert Soliday 2007-04-02