Pelegant and elegant give different results

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Qin
Posts: 11
Joined: 22 Apr 2015, 07:48

Pelegant and elegant give different results

Post by Qin » 07 May 2019, 08:05

Hi Michael,

I had a linac simulation which compresses 10pC charge, 1.5ps bunch to only about 2fs in two-stage compression. The beam is accelearted from 100 MeV to 3GeV. I have both space charge and CSR on. Using elegant and Pelegant I got different beam phase space. My elegant version is 34.4.1( Aug 17 2018) on centOS 7 (compiled from source) and I ran 8 cores with Pelegant. I also checked on a Windows machine where I used Pelegant with 4 cores. The difference still showed up.

I attached the phase space and current profile for these two cases.

Do you have any idea where this difference might come from?

Thanks
Qin
Attachments
LongPS-parallelElegant.png
current-parallelElegant.png
current-parallelElegant.png (6.1 KiB) Viewed 2472 times
current-nonparallelElegant.png
current-nonparallelElegant.png (6.06 KiB) Viewed 2472 times

michael_borland
Posts: 1452
Joined: 19 May 2008, 09:33
Location: Argonne National Laboratory
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Re: Pelegant and elegant give different results

Post by michael_borland » 22 May 2019, 14:36

Qin,

CSR tends to amplify small differences, so it is quite sensitive to any changes in the simulation. One difference between elegant and Pelegant will come in the random number generators, so synchrotron radiation (ISR=1 on CSRCSBEND) will be different. I'm surprised by the magnitude of the difference, though. You may want to trying using more particles.

It that doesn't solve the problem, please send the input files and I'll look at it in more detail.

--Michael

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