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Re: [Opal] charge per macroparticle for long emission times

Chronological Thread 
  • From: "Adelmann Andreas (PSI)" <andreas.adelmann AT>
  • To: Dragos Constantin <dragos.constantin AT>
  • Cc: "opal AT" <opal AT>
  • Subject: Re: [Opal] charge per macroparticle for long emission times
  • Date: Tue, 28 Jul 2020 18:32:47 +0000
  • Accept-language: en-US, de-CH

Hello Constantin with the next version the beam attribute BUNCHED will not be 
available anymore. 
Therefore, I think you need to adjust the BFREQ for example as you sugested
to 1/emission_time. 

Cheers A
Dr. sc. math. Andreas (Andy) Adelmann
Head a.i. Labor for Scientific Computing and Modelling 
Paul Scherrer Institut OHSA/ CH-5232 Villigen PSI
Phone Office: xx41 56 310 42 33 Fax: xx41 56 310 31 91
Zoom ID: 470-582-4086 Password: AdA
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 Jul 2020, at 18:32, Dragos Constantin <dragos.constantin AT> wrote:

Dear colleagues,
I am using the AWAGun-1 as a toy model. In there I have modified the emission
time to be several times longer than 1/f0 to mimic a non-pulsed cathode. As a
consequence the bunching is performed by the RF-field.

Regarding current and charge, normally one will specify the charge/bunch for
really short bunches and multiply that with f0 to get the current. In that
situation the bunch is no longer than 1/f0, i.e. it is spatially contained in
one RF period..

When the emission time is longer than 1/f0, how is the beam current, the
number of macroparticles, and their associated charge related? Normally one
would do

macroparticle_charge = (beam_current * emission_time) /

but I suspect 1/fo is involved (because BFREQ=f0 in the BEAM command), and I
will have to scale the beam current to have the correct charge/macroparticle.

Conversely, to eliminate f0 from the equation, should I specify the following


in the BEAM command?

What is the correct and consistent way of dealing with this issue?


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