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IBSCATTER

A simulation of intra-beam scattering.
Parallel capable? : no
Parameter Name Units Type Default Description
FACTOR   double 1 factor by which to multiply growth rates before using
CHARGE $C$ double 0.0 beam charge (or use CHARGE element)
DO_X   long 1 do x-plane scattering?
DO_Y   long 1 do y-plane scattering?
DO_Z   long 1 do z-plane scattering?
NSLICE   long 1 The number of slices per bunch
SMOOTH   long 1 Use smooth method instead of random numbers?
FORCE_MATCHED_TWISS   long 0 Force computations to be done with twiss parameters of the beamline, not the beam.
ISRING   long 1 Is it storage ring?
INTERVAL   long 1 Interval in passes at which to update output file.
FILENAME   STRING NULL Output filename.
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 is used for simulating intra-beam scattering (IBS) effect. The IBS algorithm is based on the Bjorken and Mtingwa's [15] formula, and with an extension of including vertical dispersion. It can be used for both storage ring and Linac.

To initialize IBS calculation, one or more IBSCATTER elements must be inserted into the beamline. elegant calculates the integrated IBS growth rates between IBSCATTERs (or from beginning of the beamline to the first IBSCATTER), then scatter particles at each IBSCATTER element. Beam's parameters are updated for use in downstream elements.

This method requires that IBSCATTER can not be installed at the beginning of beamline. The number of other elements between IBSCATTERs or from the beginning of beamline to the first IBSCATTER has to be 2 or more. For storage ring, an IBSCATTER must be installed at the end of beamline.

Because the IBS growth rates are energy dependent, special caution is needed for calculations with accelerating beam. The user needs to split their accelerating cavity into several pieces, so that $\gamma$ has no large changes between elements.

The user can examine the calculation through an optional SDDS output file - filename. The file has a multiple page structure. Each slice at pass $i$ at each IBSCATTER element occupies one page. Each page contains integrated IBS growth rates between IBSCATTERs (or from beginning of the beamline to first IBSCATTER) as parameters, and local rates for elements in between as tabular data.


next up previous
Next: ILMATRIX Up: Element Dictionary Previous: HMON
Robert Soliday 2014-03-21