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Re: [Opal] Cavity Benchmark against Elegant/Parmela

From: Christof Metzger-Kraus <christof.j.kraus AT gmail.com>
To: "Taubert, Sebastian" <taubert AT uni-mainz.de>
Cc: "opal AT lists.psi.ch" <opal AT lists.psi.ch>
Subject: Re: [Opal] Cavity Benchmark against Elegant/Parmela
Date: Tue, 8 Mar 2022 18:18:59 +0100
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Hi Sebastian,

sorry for the late answer, I was sick last week. It seems that the radial electrical field is much higher than what one would expect in the field maps. If I set the radial component in TESLA_FULL_CELL.T7 to zero then I don't get any additional defocusing.

Christof

On Tue, Mar 1, 2022 at 5:49 PM Taubert, Sebastian <taubert AT uni-mainz.de> wrote:

Hi,

For some time now, I fail to reproduce Elegant simulations in OPAL regarding an electron beam passing a module of two cavities. Attached to this mail, you can find the inputfile for OPAL including fieldmaps (the input distribution was too big to attach to this mail).

Also attached are two pictures of beta distributions. One was created with the above mentioned OPAL simulation and the other one is the same cryomodule with the same input distribution in Elegant. You can see that the electron beam in OPAL is quite strongly focussed by the cavities (the focus is shifted from the mid to the front) and as a consequence blows up.

Also included is a parmela code which produces the same result as the elegant simulation and uses the same fieldmaps as the opal inputfile. Also, here you can see where I got the structure for the OPAL cryomodule from.

I fail to understand what causes the different behaviour. We tried to think about every difference in elegant/parmela to OPAL. Space Charge was "turned off" in all simulations. Can someone please check my input file? Maybe you can see if I have made some obvious mistakes in setting up the beam/distribution/fieldsolver etc. Anything that could explain the strange focussing behaviour.

Also I'm happy to present my thoughts and what we already tried out in a short Zoom Meeting.

Thanks in advance, have a nice evening,

Sebastian

Doctoral Student

Accelerator Physics

Institut für Kernphysik
Johannes Gutenberg-Universität Mainz
Johann-Joachim-Becher-Weg 45
D - 55128 Mainz

E-Mail: taubert AT uni-mainz.de
Office: Due to Covid-19, temporarily not in office
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[Opal] Cavity Benchmark against Elegant/Parmela, Taubert, Sebastian, 03/01/2022
- Re: [Opal] Cavity Benchmark against Elegant/Parmela, Christof Metzger-Kraus, 03/08/2022