CEA Codes forum

Dear Didier,
'TraceWin provides the following command to minimize the emittance,

MIN_EMIT_GROW k, N, ex, ey, ez, f

I tried using this command with the help of the manual but it does not work. May you please suggest how to use this command ?

I have the following issue,
1. What k is?
2. I believe N is the number of elements after which the emittance has to be minimized.
3. I am using 0 for ex, ey, ez, and f, is it correct?
4. I using the match_fam command with this MIN_EMIT_GROW command, is it alright?

I will be really grateful for your help.

Thank you

With Regards
Abhishek

Dear Abhishek,

Some examples may be easier to explain:

MIN_EMIT_GROW 1.0 63 0 0 1 1 ; The growth of the relative transverse emittance (emittance at the command position) will be minimised 63rd element after the command position.

MIN_EMIT_GROW 10.0 63 0 0 1 1 ; Same minimization but with a weight in the different other minimizations requested 10 times stronger

MIN_EMIT_GROW 1.0 63 1 1 0 0 ; Here only the longitudinal emittance will be minimised

And yes that work only when match_fam_command are used.
If it still doesn't work send me your example

Regards,

Didier

Dear Didier,
It works, thanks very much!

With Regards
Abhishek Pathak

Dear Didier,
Is it possible to change the field and/or phase of the cavity in a given range while using the MATCH_FAM commands with MIN_EMIT_GROW command? The problem is after minimization of the emittance, the solenoid fields, cavity field, and cavity phase that is obtained is very high or very low for some of the mentioned elements and therefore if we can specify the range in which the values should be varied, it will be very useful.

Thank you

With Regards
Abhishek

Dear Abhishek,

This is clearly not possible with the MATCH_FAM_XXX based system, you will have to use the ADJUST commands which allow the definition of ranges associated with DIAG_XXX elements. In general this second way is much more powerful than the first one and I always suggest users to use it preferably.

Regards,

Didier