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Re: [Opal] wakefield from Green's function in OPAL-t

Chronological Thread 
  • From: Philippe Piot <philippe.piot AT>
  • To: "Snuverink Jochem (PSI)" <jochem.snuverink AT>
  • Cc: Christof Metzger-Kraus <christof.j.kraus AT>, opal <opal AT>
  • Subject: Re: [Opal] wakefield from Green's function in OPAL-t
  • Date: Wed, 15 Jul 2020 07:26:59 -0500
  • Authentication-results: localhost; iprev=pass ( smtp.remote-ip=; spf=pass; dkim=pass header.s=20161025 header.a=rsa-sha256; dmarc=pass

  No worries, I am actually working on it (I thought it would be a good exercise). I found a couple of bugs already. One very simple, I think the itsAttr[FNAME] should be Attributes::makeString and not Attributes::makeStringArray. I am going through the GreenWakeFunction.cpp code as I seems to be losing the beam when I turn on the wake (while my wake is "benign" and should just modulate the beam). As a benchmark, I am focusing on the LONG-SHORT-RANGE type for now. Also, the way the sdds file are read is not robust: it seems like the code assume there are two columns and just count the head of the file to get the number of points (assuming the header is 6 lines) and then assume the variable tabulated are z and the wake, and a dummy column (why?). But let me figure out what is wrong with the wake first.  All the best,  -- Philippe.

On Wed, Jul 15, 2020 at 7:14 AM Snuverink Jochem (PSI) <jochem.snuverink AT> wrote:

Dear Philippe,


Thanks for reporting. Very sorry to see that not even a message was printed :-( .. I opened an issue to follow this up:


Best, Jochem


From: Philippe Piot <philippe.piot AT>
Sent: Dienstag, 14. Juli 2020 18:16
To: Snuverink Jochem (PSI) <jochem.snuverink AT>
Cc: Christof Metzger-Kraus <christof.j.kraus AT>; Nicole R Neveu <nneveu AT>; opal <opal AT>
Subject: Re: [Opal] wakefield from Green's function in OPAL-t



  It turns out, according to the source, that the wake module I am using "LONG-SHORT-RANGE" is not implemented if I am not misunderstanding...  So I will try to separate implement the LONG-SHORT-RANGE and TRANSV-SHORT-RANGE which seems to be implemented. I should have catch this earlier (may there should be some message like "Feature unavailable" for LONG-TRANSV-SHORT-RANGE or it should be removed from the manual to avoid confusion). 

  If somebody has example of the LONG-SHORT-RANGE or TRANSV-SHORT-RANGE I am still interested though! All the best,  -- Philipe. 


OpalWake.cpp ln 233: 

    } else if (Attributes::getString(itsAttr[TYPE]) == "LONG-TRANSV-SHORT-RANGE") {




On Thu, Jul 9, 2020 at 8:58 AM Snuverink Jochem (PSI) <jochem.snuverink AT> wrote:

Hi Philippe,


That issue was unrelated I am afraid.


Some additional simple examples would definitely be great!


Thanks, Jochem


From: opal-request AT <opal-request AT> On Behalf Of Philippe Piot
Sent: Donnerstag, 9. Juli 2020 15:51
To: Christof Metzger-Kraus <christof.j.kraus AT>
Cc: Nicole R Neveu <nneveu AT>; opal <opal AT>
Subject: Re: [Opal] wakefield from Green's function in OPAL-t


Sorry, I meant Jochem; see  .  But let me look at Nicole's file and maybe contribute by preparing some simple examples to share with others. Best, -- Philippe. 


On Thu, Jul 9, 2020 at 8:40 AM Christof Metzger-Kraus <christof.j.kraus AT> wrote:

Hi Philippe,


I guess you mean this ticket (?). Unfortunately it is quite old and I won't have the time to implement it any time soon. I hope Nicole has all the information you need!


Best regards,



On Thu, Jul 9, 2020 at 2:33 PM Philippe Piot <philippe.piot AT> wrote:

Hi Nicole, 

  No, nobody replied to me but I saw Christof opened an issue and was playing with a Wakefield regression test so I suspect he is looking into this. I just wanted to implement the longitudinal and transverse wake, if you have a file handy I would be grateful if you could share it so can see if I am doing something wrong (I use the same adds format as elegant as mentioned in the user manual). 

  By the way, do you have an example of optimization setup for OPAL (I think you did many of the bunch length-emittance) but I cannot recall if you were using OPAL or the external optimizer you developed (I am interested in the internal OPAL optimizer)? 

  I hope all is well with you. All the best,  -- Philippe. 


On Thu, Jul 9, 2020 at 7:25 AM Nicole R Neveu <nneveu AT> wrote:

Hi Philip,


Did anyone get back to you on the wakefields?

I used them a while ago while at AWA, but  in version 1.9.

I can dig up those files….


I agree this needs some attention in the manual.






From: <opal-request AT> on behalf of Philippe Piot <philippe.piot AT>
Reply-To: "philippe.piot AT" <philippe.piot AT>
Date: Wednesday, June 24, 2020 at 6:30 AM
To: opal <opal AT>
Subject: [Opal] wakefield from Green's function in OPAL-t


Dear All,

  Could somebody share an example on the use of external sdds file to model the effet of wakefields in OPAL-t. I would like to account for both the longitudinal and transverse (dipole) wakefield -- I assume I have to use 2 WAKE elements with the  LONG-SHORT-RANGE, TRANSV-SHORT-RANGE or does the LONG-TRANSV-SHORT-RANGE enable the simultaneous modeling of both types of wake? Section 18 on wakefield does not have a lot of details. Thank you very much for your help. All the best, -- Philippe.

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