3D codes: TraFiC4 and CSRtrack

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3D codes TraFiC4 and CSRtrack

• Torsten Limberg
• DESY
• Zeuthen 2003

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As an introduction a few slides fromCSR code
benchmarking3-D vs. 1-D models(M. Dohlus)
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Simulation Models
projected model (Borland, Emma, ...)
phase space (eg. particle tracking)
1d charge density, 1d self-field
neglect transverse forces neglect transverse beam
dimensions neglect deformation of retarded
distribution (?(s,t) ? ?(s-c0t)
local rigid bunch approximation) extract 1d
singularity
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?-bunch instability (Borland, Emma, Saldin,
Schneidmiller, Yurkov, Kim, Stupakov ...)
initial shape and energy distortions are
amplified transverse emittance uncorrelated
enegy spread are counteracting
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Simulation Models
sub-bunch models (trafic4, R.Li, tredi...)
field generating sub-bunches with fixed shape (so
far) sampling particles (field monitors) selfconsi
stent calculation of generating sub-bunches and
sampling particles
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reasons to mistrust the projected model
transverse bunch shape neglected transverse
cross-section of bunch neglected transverse
dependence of longitudinal forces neglected no
space charge fields no compression work no
transverse forces
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charge distribution at end of magnet 3
retarded charge distribution at end of magnet
3 (observer is center particle)
retarded projected distribution
head is neglected !
retarded 2d charge distribution
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500 MeV case longitudinal profile
projected model
tilted 4x10001
conditions for non-selfconsistent model are not
fulfilled for q gt 0.2nC
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Conclusions
projected model

• fast efficient
• misses important physical effects
• some results seem to be correct (eg. ?-bunch
  instab.,
• 
  benchmark bc transv. phase space)
• it is not clear under what conditions

trafic4-like tilted models

• complete field calculation for generating
  distribution
• transverse dimensions forces are not
  negligible
• modeling of slice dimensions not quite satisfying

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First Version of 3D CSR Tracking Code Wake
Simple Input Deck
3D-CSR Solver from first principles With 1-3 D
distributed sub-bunches M. Dohlus
Fortran Tracking Code (no quads...)
Plot Beam Parameters with GNUPLOT
Output file
T. Limberg
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TraFiC4 (A. Kabel)
http//www.stanford.edu/akabel
Readable Input Deck (Bison Parser) Variable Bunch
Set Up
3D-CSR Solver from first principles With 2-3 D
distributed sub-bunches M. Dohlus
Self-consistent C Tracking Code (parallel
processing with MPI)
Plot Beam Parameters with GNUPLOT T4P2 (P. Piot)
Big structuredOutput file containing phase
space, fields, RMS values etc.
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CSRtrack
Simple Input Files for Calculation
Parameters,Lattice, Mesh, Initial Particle
Distribution
1D projected method 3D-CSR Solver With variable
sub-bunch length Greens-function method
Self-consistent Fortran Tracking Code (parallel
processing with MPI)
Separate File for Fields and Phase Space at each
Mesh Point
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CSRtrack Interfaces

• Provide Matlab (or Octave) routines to interface
  the simple CSRtrack files and to other codes like
  elegant and ASTRA

F. Stulle
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Status

• All necessary Interface routines exist in a basic
  form
• First calculations for S2E done. Performance on a
  linux cluster with 20 cpus (900 MHz)
• XFEL bc-3 with 50 mesh points, 200 field
  generating particles, 200 test particles
  distributed transversely to calculate slice
  emittance growth and optics mismatch ca.5min
• 200 field generating particles, 5000 test
  particles ca.2.5h

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To be done

• Introduce Quadrupole Magnets
• Track vertical plane
• Improve Interface routines for comfortable S2E
  simulations
• ...