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Re: [Opal] Space charge effect in photoinjectors

From: Adelmann Andreas <andreas.adelmann AT psi.ch>
To: Dr Oznur Apsimon <omete.phys AT gmail.com>, "can.davut AT manchester.ac.uk" <can.davut AT manchester.ac.uk>
Cc: "opal AT lists.psi.ch" <Opal AT lists.psi.ch>
Subject: Re: [Opal] Space charge effect in photoinjectors
Date: Sun, 2 Jul 2023 08:24:19 +0000
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Hi in case you need to change the charge of your bunch you need to modify

REAL beam_bunch_charge = xxx; // Charge of bunch. (C)

and NOT bcurrent.

Cheers A
------
Dr. sc. math. Andreas (Andy) Adelmann
Paul Scherrer Institut OHSA/D17 CH-5232 Villigen PSI
Phone Office: xx41 56 310 42 33 Fax: xx41 56 310 31 91
Zoom ID: 470-582-4086 Password: AdA
Zoom Link: https://ethz.zoom.us/j/4705824086?pwd=dFcvT1pMMGY0bHg0dTNncUNZZTJkZz09

-------------------------------------------------------
Friday: ETH HPK G 28 +41 44 633 3076
============================================
The more exotic, the more abstract the knowledge,
the more profound will be its consequences.
Leon Lederman
============================================

On 29 Jun 2023, at 08:32, Adelmann Andreas <andreas.adelmann AT psi.ch> wrote:

please send us a reproducer. What version of OPAL do you use?

Cheers A
------
Dr. sc. math. Andreas (Andy) Adelmann
Paul Scherrer Institut OHSA/D17 CH-5232 Villigen PSI
Phone Office: xx41 56 310 42 33 Fax: xx41 56 310 31 91
Zoom ID: 470-582-4086 Password: AdA
Zoom Link: https://ethz.zoom.us/j/4705824086?pwd=dFcvT1pMMGY0bHg0dTNncUNZZTJkZz09

-------------------------------------------------------
Friday: ETH HPK G 28 +41 44 633 3076
============================================
The more exotic, the more abstract the knowledge,
the more profound will be its consequences.
Leon Lederman
============================================

On 28 Jun 2023, at 12:02, Dr Oznur Apsimon <omete.phys AT gmail.com> wrote:

Hello,

From the example input files, it seems that we are not able to enter the bunch
charge directly but through beam current which is calculated as

bcurrent = charge*RF_freq

I also tried,

bcurrent = charge/(sqrt(2*pi) sigma_z)

for a Gaussian single bunch.

However, even an order of magnitude increase in charge does not create a
change in emittance unlike expected. I am trying Nbin to optimise space charge
impact calculation and using different emission models with no success.

Does anyone study low-energy electrons with space charge? Any help will be
appreciated!

Best wishes,
Oznur

Re: [Opal] Space charge effect in photoinjectors, Adelmann Andreas, 07/02/2023