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LSCDRIFT

Longitudinal space charge impedance
Parallel capable? : yes
Parameter Name Units Type Default Description
L $M$ double 0.0 length
LEFFECTIVE $M$ double 0.0 effective length (used if L=0)
BINS   long 0 number of bins for current histogram
SMOOTHING   long 0 Use Savitzky-Golay filter to smooth current histogram?
SG_HALFWIDTH   long 1 Savitzky-Golay filter half-width for smoothing current histogram
SG_ORDER   long 1 Savitzky-Golay filter order for smoothing current histogram
INTERPOLATE   long 1 Interpolate wake?
LOW_FREQUENCY_CUTOFF0   double -1 Highest spatial frequency at which low-frequency cutoff filter is zero. If not positive, no low-frequency cutoff filter is applied. Frequency is in units of Nyquist (0.5/binsize).
LOW_FREQUENCY_CUTOFF1   double -1 Lowest spatial frequency at which low-frequency cutoff filter is 1. If not given, defaults to LOW_FREQUENCY_CUTOFF1.
HIGH_FREQUENCY_CUTOFF0   double -1 Spatial frequency at which smoothing filter begins. If not positive, no frequency filter smoothing is done. Frequency is in units of Nyquist (0.5/binsize).
HIGH_FREQUENCY_CUTOFF1   double -1 Spatial frequency at which smoothing filter is 0. If not given, defaults to HIGH_FREQUENCY_CUTOFF0.

Longitudinal space charge impedance
Parameter Name Units Type Default Description
RADIUS_FACTOR   double 1.7 LSC radius is (Sx+Sy)/2*RADIUS_FACTOR
LSC   long 1 Include longitudinal space-charge impedance? If zero, acts like ordinary drift.
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 longitudinal space charge in a drift space using the method described in [22]. This is based on the longitudinal space charge impedance per unit length

\begin{displaymath}
Z_{lsc}(k) = \frac{i Z_0}{\pi k r_b^2} \left[ 1 - \frac{kr_b}{\gamma}K_1 \left(\frac{kr_b}{\gamma}\right)\right]
\end{displaymath} (28)

If L is 0 and LEFFECTIVE is not, then the element provides a LSC kick with impedance given by $Z_{lsc} L_{effective}$. This can be used to insert an LSC kick that integrates the longitudinal space charge effect of a section of a lattice. This should be used only for cases where there is very little relative longitudinal motion of particles.


next up previous
Next: LSRMDLTR Up: Element Dictionary Previous: LRWAKE
Robert Soliday 2014-06-26