CEA Codes forum

Dear URIOT

I was trying to run Toutatis, but its manual does not explain what are these terms which are given below ??...Can you please send me full manual of Toutatis so that i can build up input file.

RHO 0.85
linac 1 0.045 352.21 1.00837361135 1

input -6 100000 121.1 3.118 0.153237767251 1.214 3.123 0.153237767251 180. 0.
scheff 50
exit
ffl 0.4
vfac 1.00

Thanks
Sarvesh

Also one more question, how to generate survivor ellipse from a Toutatis run?

Hi

These commands are addressed in page 8 of the manual and the instructions refer to the file example.inp that adds explanations. For your information, we are revisiting the doc to limit such situations in the future. Anyhow:

RHO 0.85 => this is the ratio between rho/R0. Historically for the whole RFQ but nowadays it is only relevant in the RMS if you decide to keep this ratio constant when the R0 is decreasing along this section.

linac 1 0.045 352.21 1.00837361135 1
=> linac 1 <<input energy in MeV>> << frequency in MHz>> <<paticle mass in uma>> << charge state in e or Z>>

input -6 100000 121.1 3.118 0.153237767251 1.214 3.123 0.153237767251 180. 0.

=> input -6 << number of particles>> <<Twiss alpha in X>> <<Twiss beta in cm/rad in X>> <<geometrical emittance in pi.cm.rad in X>> <<Twiss alpha in Y>> <<Twiss beta in cm/rad in Y>> <<geometrical emittance in pi.cm.rad in Y>> <<phase extend half width, so 180 means continuous beam>> <<energy spread in MeV>>

scheff 50

=> scheff <<beam current in mA>>

exitffl 0.4 => length of fringe field section in cm

vfac 1.00 => factor multiplying the voltage. Useful when you want to simulate a decreased amplitude when fields ramp up in our cavity for instance.

Best,

Romuald

Could you elaborate on "survivor ellipse" please?

R

Thanks URIOT
Survivor ellipse means the particles at the input of RFQ which survived at the end of RFQ.

I understand you would like to plot the acceptance of the RFQ. Well, I would do as for any other part of a linac, set no space charge and simulate a large beam (large transverse emittances) and activate the output rfq.plt with the command:

COMPRESSION_FACTOR 0

At the end of the run you should get a file rfq.plt that you can plot with PlotWin. The file contains the history of the particles at each RFQ cell and PlotWin allows you to tag the survivors at the end and look back where they were at input.

PlotWin is free.

I hope it helps,

Romuald

and not URIOT

The toutatis run of RFQ shows 91% transmission and 87.5 accelerated window transmission but when generated tracewin file from Toutatis, is run by Tracewin then it shows 85% transmission. What may be possible reason of not matching in TRACEWIN and Toutatis ?

Thanks Romuald, Just one more general question, Is there any benchmarking of RFQGEN with PARMTEQM ? Do both converge to same RFQ geometry for given constraints and optimization criteria?

About the transmission discrepancy, be sure you use the last version of Toutatis and TraceWin. The part of the Tracewin code simulating RFQs is actually Toutatis as a library. So you should get exctaly the same results. Also take care of the new commands:

DW_FILTER dW => make that Toutatis will use a moving window Wref+/-dW along the simulation for filtering particles taken into account for statistic estimates like emittances

DW_LIMIT dW => Particles outside the moving window Wref+/-dW will be declared lost at the moment they get out of the window.

About RFQGen and PARMTEQM, these are Los Alamos codes that I am not so familiar with. Anyhow, are you asking if there is a benchmark between Los Alamos codes and Saclay codes?

For a comparison between PARMTEQM and Toutatis, the answer is definitely yes. This was my PhD thesis. I attached it. Between RFQGen and RFQ Designer, I do not think that such comparison exists.

Best,

Romuald

Hi URIOT

We have a scaling factor for voltage in RFQs, Is there any way to declare it as variable and search for maximum transmission out of RFQ in toutatis or Tracewin?

Thanks
Sarvesh