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LRWAKE

Long-range (inter-bunch and inter-turn) longitudinal and transverse wake
Parallel capable? : yes
Parameter Name Units Type Default Description
INPUTFILE   STRING NULL name of file giving Green function
TCOLUMN   STRING NULL column in INPUTFILE containing time data
WXCOLUMN   STRING NULL column in INPUTFILE containing longitudinal Green function
WYCOLUMN   STRING NULL column in INPUTFILE containing horizontal Green function
WZCOLUMN   STRING NULL column in INPUTFILE containing vertical Green function
FACTOR   double 1 factor to multiply wakes by
XFACTOR   double 1 factor by which to multiply longitudinal
YFACTOR   double 1 factor by which to multiply horizontal
ZFACTOR   double 1 factor by which to multiply vertical
TURNS_TO_KEEP   long 128 number of turns of data to retain
RAMP_PASSES   long 0 Number of passes over which to linearly ramp up the wake to full strength.
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 provides serial and parallel modeling of long range, multi-bunch, multi-pass, non-resonant wakes. Resonant wakes can be modeled using the *RFMODE elements, while short-range wakes are modeled with WAKE, TRWAKE, ZLONGIT, ZTRANSVERSE, and RFCW.

For the LRWAKE element, the beam is assumed to be bunched and wakes are computed bunch-to-bunch. The long-range wake is assumed to be constant within any single bunch.

To use this element, the beam has to be prepared in a special way so that elegant can recognize which particles belong to which bunches. See Section 6 for details. Given a properly prepared beam, the algorithm works as follows.

To use LRWAKE, the user provides the wakes (functions of t) in an SDDS file. These wakes may extend over an arbitrary number of turns, with the user declaring how many turns to actually use as part of the element definition. However, they should be zero within the region occupied by a single bunch, to avoid double-counting with the true short-range wake. (Note that the above sums include the self-wake.) Similarly, the short-range should be zero for times comparable to the bunch spacing.


next up previous
Next: LSCDRIFT Up: Element Dictionary Previous: LMIRROR
Robert Soliday 2014-03-21