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

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

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)

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.

Effect of Noise (1st bend - no screening)

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 - 400 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)

In Zehuten: Phase space at exit  still noisy !

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

5 GeV – 1 nC Gaussian

5 GeV – 1 nC Gaussian

5 GeV - 1 nC Gaussian

5 GeV – 0.5 nC Gaussian

5 GeV – 0.5 nC Gaussian

5 GeV – 0.5 nC Gaussian

5 GeV – 1.0 nC Uniform

5 GeV – 1.0 nC Uniform

5 GeV – 1.0 nC Uniform

500 MeV 1.0nC Gaussian

500 MeV 1.0nC Gaussian

500 MeV 1.0nC Gaussian

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) http://www.desy.de/csr 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 -0.0043 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

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 ?