RFCA/ RFCW

[olivia.karlberg]

Hi Michael and collaborators,

I am a new user of ELEGANT and I think I need some help/ advice.
I am tracking particles in a linac and I want to apply an error/ a misalignment to EVERY cavity in a linac structure. To do that, I changed the line of RFCA-cavities (case1) into RFCW-cavities (case 2). In this way every "lin"-structure can be misaligned randomly with the help of the error_element in a later process. But something is wrong here, the case1 and case2 doesn't give the same result at all (without the error elements)!? What am I missing? Could you give me some comments? (please, see attached txt-file).

Thanks,
Best Regards,

Olivia

[michael_borland]

Olivia,

Can you also post a .ele file that illustrates how you are using this lattice?

--Michael

[olivia.karlberg]

Hi Micheal,

Here is the .ele file that I used. (see attached file)

Thanks, Best Regards

Olivia

[michael_borland]

Olivia,

Sorry, I'll need the daresburyastrain.sdds, wakefieldlong.sdds, and wakefieldtran.sdds files as well.

--Michael

[olivia.karlberg]

Hi Michael,

I'll attached the other three files. Unfortunately, I didn't manage to compress one of the files which was quite large, so I divided it into three pieces. I'm sorry for the inconvenience!!
Thank you for your help,

Best Regards

-Olivia

[olivia.karlberg]

The two last files...

[michael_borland]

Olivia,

There are two problems I see:

1. The VOLT parameter is set to the same value in both element definitions. However, they should have a ratio of the number of cells (156), since VOLT value is the total voltage, not the gradient.

2. When splitting linac cavities, it is advisable to tell elegant that they are linked in phase. By default, elegant phases any cavity to the first beam that comes past. However, since the beam is not traveling at v=c, this will result in the phases not being quite right. The error will be small in your case, but it doesn't hurt to make it right. You can do this by setting PHASE_REFERENCE=<id> on the definition of the RFCA cells, where <id> is a number you pick that is unique to that linac structure.

I noticed in your input file that a namelist "emittance_output" is given. Is this an extension you are adding to elegant? If so, I'd like to hear more about it.

--Michael

[olivia.karlberg]

Hi Michael,

Thank you so much for your help. It works perfectly now!
I will ask my supervisor (Sara Thorin from MAX-lab) what the input file "emittance_out" is about.

Best Regards,
Olivia