The OPAL Discussion Forum

["Snuverink Jochem (PSI)" <jochem.snuverink AT psi.ch>]

Hi Tom,

I don't know if someone already answered you. I am not an expert at all on the travelling wave element, but you can find the code implementation here:

https://gitlab.psi.ch/OPAL/src/-/blob/master/src/Classic/AbsBeamline/TravelingWave.cpp

Hope that helps,

Cheers, Jochem

---

From: opal-request AT lists.psi.ch <opal-request AT lists.psi.ch> on behalf of Lucas Thomas Geoffrey (PSI) <thomas.lucas AT psi.ch>
Sent: Tuesday, September 20, 2022 12:24 PM
To: Adelmann Andreas (PSI) <andreas.adelmann AT psi.ch>
Cc: opal AT lists.psi.ch <Opal AT lists.psi.ch>
Subject: RE: [Opal] OPAL treatment of travelling wave structures

 

Hi Andy,

 

I’m trying to completely replicate and therefore benchmark my injector simulations against the results of you/Gardar’s and also those performed in ASTRA so I don’t have an OPAL file working example (which is what I think you meant). However, here is the reconstructed 1D Ez fieldmap (blue real and red imaginary) I made using the maths from the OPAL manual with the idea that the input/output couplers are treated as standing waves and the inner cells are treated as travelling wave (both pretty valid assumptions however the actual place where they become TW from SW is more complicated as it is a gradual transition).

 

You can see the sharp edge on the fieldmap around the coupler-cell transitions. These will be of course smoothed internally in the code (well I assume). Just asking about what style of smoothing you use?

 

The reason this is a new issue is that I previously used the full 1D fieldmap from the ANSYS calculation of the TW structures however I wasn’t able to completely reconstruct your/the ASTRA results with this. I got very similar results but not as close as other benchmark studies therefore I thought to use this TWS approximation which is performed in your code as well as ASTRA rather than using the full 1D fieldmap.

Cheers,

Tom

 

__________________________________________
Paul Scherrer Institut
Dr. Thomas Geoffrey Lucas
WMHA/B17
Forschungsstrasse 111
5232 Villigen PSI
Schweiz

Telefon: +41 56 310 50 81
E-Mail: thomas.lucas AT psi.ch

 

From: Adelmann Andreas (PSI) <andreas.adelmann AT psi.ch>
Sent: Dienstag, 20. September 2022 12:06
To: Lucas Thomas Geoffrey (PSI) <thomas.lucas AT psi.ch>
Cc: opal AT lists.psi.ch
Subject: Fwd: OPAL treatment of travelling wave structures

 

Hi Tom I am forwarding this to the OPAL mailing list. Can you also add a fully working example?

Cheers A

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Paul Scherrer Institut OHSA/ CH-5232 Villigen PSI
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Begin forwarded message:

 

From: "Lucas Thomas Geoffrey (PSI)" <thomas.lucas AT psi.ch>

Subject: OPAL treatment of travelling wave structures

Date: 20 September 2022 at 11:02:52 CEST

To: "Adelmann Andreas (PSI)" <andreas.adelmann AT psi.ch>

 

Dear Andy,

 

I am looking at the OPAL manual at the section of the travelling wave structures: http://amas.web.psi.ch/opal/Documentation/master/OPAL_Manual.html#sec.elements.travelingwave

 

Using this method we achieve a nice TWS field however on the edges of the fringe field and middle cells we have a discontinuity which needs to be smoothed for the derivatives. May I ask how this is smoothed inside OPAL?

 

Best,

Tom

__________________________________________
Paul Scherrer Institut 
Dr. Thomas Geoffrey Lucas
WMHA/B17
Forschungsstrasse 111
5232 Villigen PSI
Schweiz

Telefon: +41 56 310 50 81
E-Mail: thomas.lucas AT psi.ch