Phase offset between field maps [SOLVED]

[wtam]

Dear Nicholas,

Thanks again!

Best regards,
Wai-Ming

[wtam]

Dear Didier,

Is there a handy way of extracting the "input phase" for all cavities? The closest is "Cav_set_point_res.dat" but it only contains the synchronous phase. Can you add a column to that file? Or is it recorded somewhere?

Best regards,
Wai-Ming

[Didier]

Dear Wai-Ming,

I added a culumn RF_phase

Regards,

Didier

[wtam]

Thanks, Didier.

Wai-Ming

[wtam]

Dear Didier and Nicholas,

A follow up question on the interpretation of the Input Phase (now called RF phase) for field maps at different frequencies. Please see attachment.

In the project, A1 is at 100MHz and A2 is at 200MHz. I believe the RF Phase reported for A1 is the wall clock phase counted at 100MHz, while the RF Phase for A2 is the wall clock phase counted at 200MHz. Is it correct?

In this particular example, A1 is leading A2 by:
71.2/2-(-3.1)=38.7 at 100MHz, or
71.2-(-3.1*2)=77.4 at 200MHz

Is it correct?

Best regards,
Wai-Ming

[npichoff]

Dear Wai-Ming,

The absolute phase of each cavity is the phase of the RF field in the cavity (oscillating with the RF frequency of the cavity) at the start of the simulation.
If you add a drift L at the start of the simulation:
- the absolute phase in A1 is reduced by: dphi_A1 = 360°*100MHz*L/(beta*c)
- the absolute phase in A2 is reduced by: dphi_A2 = 360°*200MHz*L/(beta*c) = 2*dphi_A1
for example : L = 1 mm --> dphi_A1 = 2.6° and dphi_A2 =5.2°.

I hope it is clear ?

Best regards.

Nicolas.

[wtam]

Dear Nicolas,

The 1mm test is great. I have the answer I wanted. Thanks.

Best regards,
Wai-Ming

[wtam]

Dear Didier,

I am working on a phase calculation which makes me review this post.

If you go to my post on Mar 1 and Mar 3, TraceWin gave the same "input phase" for the two models if parameter10=1 (absolute phase). You have changed the name "input phase" to "RF phase" in the Data tab after some discussions. The latest version of TraceWin is giving different results. Would you mind take a look into it?

Best regards,
Wai-Ming

[Didier]

Dear Wai-Ming,

Could you be more specific, as I've compared the latest version with the one from 6 months ago and I can't see any difference, except for the name of the RF phase.

Regards,

Didier

[wtam]

Dear Didier,

Please ignore the problem that I described.

I think I am confused by Nicholas's post on Mar 15:

Q3 : Again my mistake.
2- (the RF cavity vision) corresponds to Parameter10=0 (not 1); In this case, for a same acceleration in the cavity, the phase doesn't depend on the length of the drifts between the cavities.
3- (the linac vision) corresponds to Parameter10=1 (not 0); In this case, for a same acceleration in the cavity, the phase does depend on the length of the drifts between the cavities (due to longer transit time).

Testing again, when setting Parameter10=1, the "RF phase" does NOT depend on the length of the fieldmap. This contradicts with what Nicholas said in his post.

Best regards,
Wai-Ming