CEA Codes forum

Hi Didier,

I have a couple of questions regarding the synchronous phase:

1. I've noticed that there is a tiny difference between the set input synchronous phase (-45°) and the actual synchronous phase of the first cavity (44°).
This is not immediately a problem, but I'm wondering where the difference comes from.

2. Secondly, I've noticed that the second cavity in my period always has a slightly higher synchronous phase,e.g. -44° for cav1 and -44.3° for cav2. Why is that? which rule in your algorithm causes this? I'd expect that following the const. longitudinal/phase acceptance would result in a continuous decreasing sync. phase...

3. When I apply the equation for const. longitudinal acceptance myself I get slightly different sync. phases for subsequent cavities, e.g. for the first cavity in the second period, I find -42.8°, while GLW finds -43.3°. (Proton energy at the LINAC entrance = 16.6 MeV, and at the entrance of period2 = 17.2 MeV).

If needed, I can send you the project files in a private message.

Cheers,

Lennert

Dear Lennert,

Points 1 and 2 were definitely caused by a bug that I recently introduced by mistake and have now fixed. You can upgrade your software. This will probably fix point 3 as well, but you'll have to let me know.

Regards,

Didier

Dear Didier,

Yes, that does the trick! Thanks a lot.
Is there a particular reason why you don't update the subsequent cavities in a period with the acceptance law, and instead use the same sync. phase as the first cavity?

Cheers,

Lennert

Dear Lennert,

This is because the synchronous phase is adjusted at the beginning of each period only once, so all cavities in the same period have the same synchronous phase. Honestly, it wouldn't change much in the final result.

Regards,

Didier