4.2 elegant2genesis

• description: elegant2genesis analyzes particle output data from elegant and prepares a “beamfile” for input to GENESIS[8], a 3-D time-dependent FEL code by S. Reiche. The beamfile contains slice analysis of the particle data, and may be useful in other applications as well.
• examples:
  elegant2genesis run.out beamfile.genesis  
  elegant2genesis run.out beamfile.gen -totalCharge=3e-9 -slices=100  
    

• synopsis:
  elegant2genesis inputfile outputfile  
    [-pipe=[in][,out]] [-textOutput]  
    [-totalCharge=coulombs | -chargeParameter=name]  
    [-wavelength=meters | -slices=integer]  
    [-steer] [-removePTails=deltaLimit=value[,fit][,beamOutput=filename]]  
    [-reverseOrder] [-localFit]  
    

• files:
  • inputfile — A particle output file from elegant or any other program that uses the same column names and units.
  • outputfile — Contains the slice analysis, suitable for use with SDDS-compliant GENESIS. The columns are as follows:
    • s, t — Location of slice in the bunch, in meters or seconds, respectively. s is defined so that the head of the bunch is a larger value, contrary to elegant’s convention.
    • gamma — The average value of γ for the slice.
    • dgamma — The standard deviation of γ for the slice.
    • xemit, yemit — The normalized slice emittances in the horizontal and vertical plane, respectively.
    • xrms, yrms — The slice rms beam sizes.
    • xavg, yavg — The slice centroid positions.
    • pxavg, pyavg — The slice centroids for x and y slopes.
    • alphax, alphay — The slice values of the Twiss parameter α.
    • current — The slice current.
    • wakez — Defined for convenience to be 0. See GENESIS manual for the meaning.
    • N — The number of particles in the slice.
• switches:
  • -pipe[=in][,out] — The standard SDDS toolkit pipe option.
  • -textOutput — Requests text output instead of SDDS output, which may be useful for input to non-SDDS-compliant versions of GENESIS.
  • -totalCharge=coulombs — Gives the total charge of the beam in Coulombs.
  • -chargeParameter=name — Gives the name of a parameter in inputfile where the total charge in the beam is given.
  • -wavelength=meters — This option is misnamed. It is actually the slice length in meters.
  • -slices=integer — The number of analysis slices to use.
  • -steer — If given, then the transverse centroids for the bulk beam are all set to zero. The relative centroid offsets of the slices are, of course, unchanged.
  • -removePTails=deltaLimit=value[,fit][,beamOutput=filename] — Removes the momentum tails from the beam. deltaLimit is the maximum absolute value of (p -⟨p⟩)∕⟨p⟩ that will be accepted. If fit is given, then a linear fit to p as a function of t is performed, and removal is based on the residuals from that fit. If beamOutput is given, then the filtered beam data is written to the named file for review.
  • -reverseOrder — By default, the data for the head of the beam comes first. This option causes elegant2genesis to put the data for the tail of the beam first.
  • -localFit — If given, then for each slice a local linear fit is used to remove any momentum chirp prior to computing the momentum spread. This produces a momentum spread that is more independent of the number of slices. Should not be used if the FEL cooperation length is greater than the slice length.
• author: R. Soliday, M. Borland, ANL/APS.