RFQ cell definition

[Vyacheslav]

Hello,
please help me to tune my Project (see in an attachment

RFQ.ZIP

Project files. Contains a few structure periods.

(110.62 KiB) Downloaded 303 times

) for the correct run of the calculations.
Why Phase advance error does appear?
What is the radius of the wall aperture and how small can it be?
What do system error mean?

[Didier]

Dear Vyacheslav,

Th first message is not an error. It only means that it is not possible to calculate the kox, koy using the transfer matrix of this first period. Now before to make traking simulation, I had a first look in envelope mode and I see that the envelope explodes and there is no acceleration at all.

envelope_and_energy.png (63.27 KiB) Viewed 2506 times

I don't know exactly what this RFQ is supposed to do, but I'm surprised to see that the first cells are 9 mm long when theoretically they should be equal to beta*lambda/2 = 290 mm, according to the parameters of your input beam.
There is no chance that such a beam can be transported in this RFQ!

Regards,

Didier

[Vyacheslav]

Dear Didier, this is just an example of buncher part of RFQ. It is not suggested to accelerate particles in this section.
It is not clear for me from the Manual what is a problem with phase advance error message.
What about wall aperture and segmentation error?

[Didier]

Dear Vyacheslav,

Phase advance is calculated along the structure at each period using the trace from the transfer matrix of the period. That includes an arcos(...) function which is not alway possible to calculate, making impossible to have the phase advance. Anyway, I added a new option allowing to cancel this message (see “Simulation options” box in “Main” tab-sheet)

Toutatis code is not very resilian, some crasches could ofen occur when you tried to transport beam not at all relevant considering the RFQ structure. I've also improved the last TraceWin version to try to reduce still more this kind of problem.

For mesh reason, your wallaperture have to be bigger than Ro of the first cell. See bellow.

wallaper.png (22.07 KiB) Viewed 2494 times

So, you can upgrade your TraceWin code.

Regards,

Didier