1. L. Giannessi – M. Quattromini
TREDI test for CSR
L. Giannessi – M. Quattromini
Presented at

2. TREDI : SELF FIELDS & Retarded Potentials
R(t’)
Target
Source
TREDI
Trajectories are stored and the fields evaluation requires bracketing of
the retarded condition.
Cpu – memory consuming
Non trivial field reglarization by grid assignement (Parmela mode)
“extended particles” requires careful treatment of ret. condition

3. TREDI Features 15000 lines in C language; Scalar & Parallel (MPI 2.0);
Unix & Windows versions;
Tcl/Tk Gui (pre-processing);
Mathematica & MathCad frontends (post-processing);
Output format in NCSA HDF5 format (solve endian-ness/alignement problems)

4. Conclusions of Zehuten workshop
The noise suppression method has reduced the effects of SF on longitudinal phase space, without being completely effective in the transverse phase space
A rigorous model of fields regularization, relying on a realistic momentum dispersion of macroparticles will be soon implemented
The low number of macroparticles in severely limiting the reliability of the results
Diagnostic on fields will be implemented to improve insight on the smoothing procedure
The reason of the slow down of the code must be understood
Before the end of the workshop the 1000 particles case will be finished - we will see.

5. Effect of Noise (1st bend - no screening)

6. six months after Zehuten, Chia Laguna…
Introduced radiative energy loss (ISR)
Now use HDF5 data format support to fix endianess/alignments problems (output portability to different platforms)
?? Improved acceleration fields smothness (more work required, no manifestly covariant, CPU consuming)
Fields blow up when we have collinear divergencies –
Solution: target macro particles are given a finite extension in space
Big speed up (improved retarded time condition routine):
six months ago: very few particles (300 particles  4h on an IBM SP3/16 nodes MHz each)
Now: 1000 particles  35m on an equivalent platform
10000 particles in 27h on a 32CPUs platform
improvements and bug fixes; recently introduced a “Parmela-like” mode (instantaneous interactions,MUCH faster still experimental)

7. In Zehuten: Phase space at exit  still noisy !

8. After changes to field regularization
Ex=2.3 mm-mrad
Ex=1.8 mm-mrad

9. 5 GeV – 1 nC Gaussian

10. 5 GeV – 1 nC Gaussian

11. 5 GeV - 1 nC Gaussian

12. 5 GeV – 0.5 nC Gaussian

13. 5 GeV – 0.5 nC Gaussian

14. 5 GeV – 0.5 nC Gaussian

15. 5 GeV – 1.0 nC Uniform

16. 5 GeV – 1.0 nC Uniform

17. 5 GeV – 1.0 nC Uniform

18. 500 MeV 1.0nC Gaussian

19. 500 MeV 1.0nC Gaussian

20. 500 MeV 1.0nC Gaussian

21. ICFA Beam Dynamics mini workshop Coherent Synchrotron Radiation and its impact on the dynamics of high brightness electron beams January 14-18, 2002 at DESY-Zeuthen (Berlin, GERMANY) 3D E E 
TRAFIC4
-0.058
-0.002
1.4
TREDI*
-0.041
0.017
2.3 2D
Program by R.LI
-0.056
-0.006
1.32 1D
Elegant
-0.045
1.55
CSR_CALC
-0.043
-0.004
1.52
Program by M. Dohlus
-0.011
1.62
-0.018
-0.001
1.85
* 15% cut of charge to reduce noise

22. Conclusions
The agreement with other codes is improved with the new macroparticles model
The cpu time is greatly reduced, this allows to run a larger number of macroparticles, but not yet sufficient to simulate microbunching.
Fields regularization requires more work (still time consuming, not covariant)
The code provides reasonable results in a wide range of conditions … start to FEL simulations ?