different result of Patran and envelope

[JieLi]

Dear Didier,

Sorry to trouble you. Tracewin is a powerful tool for my study. Thank you very much. But I have some trouble with the different result of "Patran or from file" and "Envelope". For example, the envelope curve may focus in "Envelope"but defocus in "Patran or from file" . Could you please clarify their difference? And which one is more convincing when I use the simulation results?

Looking forward to your reply.

Kind regards,
Jie Li

[Didier]

Hi Jie lI,

First of all, you are not disturbing anyone on this forum, which is dedicated to your questions or suggestions.
Normally, except for very strong non-linearity, both methods should show the same results. Now, without the files of your project I can't really help you more.

Regards,

Didier

[JieLi]

Dear Didier,

Here is my file. I have two questions in the file:

1. my idea solenoid fiedlmap does not match the "solenoid element"
2. the difference of "Patran or from file" and "Envelope" in "chart"

Kind regards,
Jie Li

[Didier]

Dear Jie Li,

Please test my own project attached here.
First, I remove beam current and reduce emittance to avoid losses, because in tracking your lost most of the beam, so didn't expect see the same behavoir than linear envelope mode.
Secondly I cut your 2 meter drfits in 10 parts, because in tracking only input and ouptut beam are saved in output envelope plot making sometime complicated to see the real beam behavior between input and ouput of very long element.
Now, concerning your solenoid, if you replace its 800 mm lenght by 400 mm as the field map, that seems much more similar, no ?

Regards,

Didier

askForHelp_new.zip

(2.69 KiB) Downloaded 94 times

[JieLi]

Dear Didier,
I just make a idea solenoid field map to check the feasibility. It seems that 800mm solenoid field map does not match the "Solenoid element". You say I should check 400 mm. But it also does not match the 400mm "Solenoid element" perfectly. And I use two 400mm solenoid field map, the result is the same as the 800mm solenoid field map. Could you please tell me why my fieldmap "idea_sole" does not work? If my field map is 800mm, what should I do?

Kind regards,
Jie Li

[Didier]

Dear Jie Li,

In your project solenoid field map length is 400 mm, so I suggest you to have a single hard-edge SOLENOID element of 400 mm too. Yours is 800 mm why ?

Regards,

Didier

[JieLi]

Dear Didier,

Sorry I make a mistake. My field map "idea_sole" is 800mm long. It seems that my field map "idea_sole" results does not match the "SOLENOID" Element.
Could you please show me why this happen?

Kind regards,
Jie Li

[Didier]

Dear Jie Li,

The problem is that your field_map does not correspond to a realistic solenoid and if you look at the emittance you see it is multiplied by 300.
Instead, use the MULTIPOLE type 0 element to create a field map of a realistic solenoid. But then you have to adjust its parameters and also drift lengths to make the two fit, see example below at roughly equivalent.
You can use also field map tools from "charts" page to visualise and compare magnetic field shape for your field map and multipole element.

Code: Select all

DRIFT 40 50
MULTIPOLE 0 1400 20 4.94 100 800 100
DRIFT 1700 60
end

Code: Select all

DRIFT 340 50
SOLENOID 800 4.6436 80
DRIFT 2000 60
end

Regards,

Didier

[JieLi]

Dear Didier,

In my field map, I just set Bz to be 1T, and Bx, By is equal to 0T, just like a hard-edge model. But it does not match the result of "SOLENOID" element. However, the "SOLENOID" element is a hard-edge model, and it does not consider the real field in the edge. Is that right ? It is so confusing. I just want to check the feasibility of my field map. But it does not work.

Looking forward to your reply.

Thank you very much.

Kind regards,
Jie Li

[Didier]

Dear Jie Li,

I think your're wrong, hard-edge element include effect of field in the real

Regards,

Didier