CEA Codes forum

Dear Fancesco, Interesting work. I focused my analysis on your pdf file. In the first set of simulations (pages 1-5), the beam generated by TW is CW. The results of the simulation are "as expected" : when frequency is low, the longitudinal mesh is bigger and each macro-particle is representing a big...

Dear Francesco, The frequency given in main page is the beam repetition frequency (RF is an harmonic of it). In one sense, this frequency has no importance for a CW beam. Nevertheless, it has just an importance for the space charge routine calculation, as it defines the longitudinal size of the mesh...

Dear Francesco, Intrinsically, TraceWIN (and its space-charge routine) is dealing with bunched beams. Nevertheless, it considers that beam is periodic with the frequency (fbeam [Hz=/s]) given in TraceWIN. The beam spacial period [m] is then beta*lambda, where : - beta is the beam reduced speed, - la...

For a better understanding of Hoffman chart, may I suggest that you read Ingo's (Hoffmann) paper ? I forget to mention that it is plot for RFQ only. OK. this explain the reason why you have a lot of dots with kz<<kw (during the bunching process). Can we also say that there is fast crossing of four l...

Dear Sarvesh, Can we say also that it is plot of σT/σ0T versus σz/σT? You are right : w is for x or y, then w=T=transverse (generaly, in linac, the focusing is the same in both transverse directions). Can you please correlate the X and Y axis in this way. This is a specific development. Nevertheless...

Yes, it is possible, nevertheless, don't forget that a beam is a plasma with a preferential direction and some of the calculations (especially envelops) consider assumptions like dx/ds^2/dy/dz^2 << 1 (x' and y' << 1).

Dear Jie Li, In field maps, the reference trajectory is calculated by transportation with time of the reference particle* in the field map (in X, Y, Z, pX, pY, pZ). The beam particles are also transported in time in the field map (in X, Y, Z, pX, pY, pZ) and they position (x, x', y, y', phase, Energ...

Dear Wai-Ming, I also did this recently on my laptop (Windows) and observe no overhead (maybe to short to be significant in my calculation. I used the instruction : "dos('TraceWin_noGUI xxx.ini >res.dat');" Note that the TraceWin_noGUI is in the same directory as the matlab file. Best regards. Nicol...

My pleasure.
Have fun with beam dynamics !

Dear QiXinimp, When the beam bunch is longer than 180° (based on a RMS calculation), PICNIC does 2 things: - It puts temporary (just for the SC calculation) each particle that is out of +/-180° main window by -/+360° until it comes back to the main window, - It adds neighboor bunchs on each side (+/...