CEA Codes forum

Dear Bruce, You are right. TraceWin (and PICNIC) are natively written for bunched beam. The way we "simulate" cw beam (as described before) is a little bit tricky (not perfect) and then can produce unexpected effets on beam border. (~-180° and ~+180°). The effect shown here is small (<1% (30eV) and ...

Dear Rajni, Using visualisation of (r, r') is my sugestion. In a solenoid channel, it has a physical meaning and is "equivalent" of working in "Larmor" frame. The (r, r') distribution has some sort of "uncoupled continuity" in this axialy-symetrique dynamics. In a solenoid channel, (x, x) and (y, y'...

Dear Rajni,

TraceWIN allows following the particle r = sqrt(x^2+y^2) and r' = dr/ds coordinates.
You can plot the (r, r') phase-space evolution, including visualising (r,r') emittance.
It might correspond to your need ?

Best regards.

Nicolas.

Dear Wai-Ming, The absolute phase of each cavity is the phase of the RF field in the cavity (oscillating with the RF frequency of the cavity) at the start of the simulation . If you add a drift L at the start of the simulation: - the absolute phase in A1 is reduced by: dphi_A1 = 360°*100MHz*L/(beta*...

Dear Wai-Ming, Q1 : Correct. Q2 : Correct, my mistake ! Q3 : Again my mistake. 2- (the RF cavity vision) corresponds to Parameter10=0 (not 1); In this case, for a same acceleration in the cavity, the phase doesn't depend on the length of the drifts between the cavities. 3- (the linac vision) corresp...

Dear Wai-Ming, Didier asked me to try to explain the principle of TraceWIN RF phase management. In traceWIN, the linac is generated with the help of a synchronous particle. At the start of the simulation, a global clock, oscillating at the Bunch Frequency f_bunch (given on "Main" page) starts at 0°....

Dear Max, The model implemented in TraceWIN is the Compton elastic scattering on nucleus of residual gas as explained here : https://accelconf.web.cern.ch/e96/PAPERS/MOPL/MOP017L.PDF It is well appropriated with particles whose velocity is much higher than the electron velocity in atoms (a few eV/51...

Dear Warson, 1- if (dx, dy, dz) is the signed distance with respect to the closest cell (in fact the cell where the particle stands). In fraction of mesh size (Xc, Yc and Zc), it means that -0.5 < dx/Xc, dy/Yc, dz/Zc < 0.5). The particle charge is deposited in the eight closest cells, with weights w...

Dear msh3069, May I suggest that you coudl use the gas command with density as high as solid followed by a very short drift with the length of the foil ? I believe that, in theses conditions, you might have to reduce the step in the drift/foil to consider properly multiple scattering. Best regards. ...

Dear Francesco,
I transmit your question to Didier who is more competent than me for this type of question (use of TraceWIN).
Best regards.
Nicolas