Dear all,
The problem is already solved. We were trying to simulate a DC extraction in an Ion source Test Bench. In order to simulate a DC field we imposed a very low RF frequency. However, we used the same low value for the bunch frequency. In such conditions, the charge per bunch was huge, resulting in an unusual SC and consequently the beam virtually exploded.
Many thanks your help,
Best regards
Pedro Calvo and Conchi Oliver
El sáb, 11-02-2017 a las 16:15 +0000, Daniel Winklehner escribió:
Hi,
I don’t know the exact reason Jianjun decided to turn off SC calculation for <1000 particles, but it might have something to do with OPAL handling the distribution of particles onto different CPU cores back then. To be clear, you can always turn OFF space charge calculation by just using solver=NONE instead of solver=FFT or solver=SAAMG. But for <1000 particles there is currently no way of turning it ON. At least in OPAL-cycl.
These should give you the same results:
999 particles
1000 particles + solver=NONE
If that is not the case, then there is something wrong in the ParallelCyclotronTracker.cpp
These might give you different results depending on space charge (real physics), units/geometry errors (user mistake), or OPAL internal errors (bug in the field solver?) :
1000 particles + solver=FFT
1000 particles + solver=SAAMG
As to what’s going on in the field solver and whether or not there is a mistake in OPAL, I can only determine if you give me access to the input files. I need to know things like what field solver you are using, if there is a geometry, if you are going to energies where relativistic effects become important, etc…
The fact that only one particle survives the first step could be an indicator for a units problem. If OPAL thinks the surrounding geometry is 1000 smaller than it should be, then the bunch could be almost completely outside and would be terminated… Or maybe space charge is way too high for some reason and the bunch just explodes, leaving only the center particle inside the accelerator.
Best,
Daniel
P.S.: While writing this, I saw your other email with the Dropbox share, I’ll take a look now.
From: Concepción Oliver [mailto:concepcion.oliver AT ciemat.es]
Sent: Saturday, February 11, 2017 10:38
To: Daniel Winklehner <winklehn AT mit.edu>
Cc: Christof Metzger-Kraus <christof.j.kraus AT gmail.com>; Adelmann Andreas (PSI) <andreas.adelmann AT psi.ch>; Calvo Portela, Pedro <Pedro.Calvo AT ciemat.es>; opal <Opal AT lists.psi.ch>
Subject: RE: [Opal] Error OPAL
Dear all,
sorry but It's not clear for me. What we have seen is that simulations with particles >1000 gave wrong results. In fact only one particle survives after the first steps, even with very similar initial conditions. With a particle number <1000 the behavior is what we have expected. So, following your emails, I have different questions:
- Do you mean that with "macroparticles" <1000, the SC is off and when you move to simulations with a particle number >1000 the SC is automatically on? Is there any way to track a high number of particles with SC off? It could be interesting to analyze the SC effects
- If there were any wrong units somewhere we would have obtained some wrong results even with a low number of particles, wouldn't we?
Cheers
Conchi
El sáb, 11-02-2017 a las 14:58 +0000, Daniel Winklehner escribió:
I remember having similar errors when using the wrong units somewhere (geometry, particle distribution, …).
Could it be that simple? Can you send me the link to the Dropbox folder with the input files?
Best,
Daniel
From: opal-request AT lists.psi.ch [mailto:opal-request AT lists.psi.ch] On Behalf Of Christof Metzger-Kraus
Sent: Saturday, February 11, 2017 03:50
To: Adelmann Andreas (PSI) <andreas.adelmann AT psi.ch>
Cc: Oliver Amoros, Concepcion <concepcion.oliver AT ciemat.es>; Calvo Portela, Pedro <Pedro.Calvo AT ciemat.es>; opal <Opal AT lists.psi.ch>
Subject: Re: [Opal] Error OPAL
We now know why we have a different behavior when run with 999 particles than with 1000. But the main problem isn't solved: why does OPAL crash when SC is on? It looks to me like the mesh isn't adapted to the particle distribution when computing SC. boundp missing or not at the correct location?
cheers,
christof
On Sat, Feb 11, 2017 at 8:38 AM, Adelmann Andreas (PSI) <andreas.adelmann AT psi.ch> wrote:
Hi is the problem solved/understood?
Andreas
> On 10 Feb 2017, at 19:12, Oliver Amoros, Concepcion <concepcion.oliver AT ciemat.es> wrote:
>
> Hello,
> We use matlab by extracting the informatíon in the .h5 file.
> Conchi
> ________________________________________
> De: opal-request AT lists.psi.ch [opal-request AT lists.psi.ch] en nombre de Adelmann Andreas (PSI) [andreas.adelmann AT psi.ch]
> Enviado el: jueves, 09 de febrero de 2017 12:05
> Para: Calvo Portela, Pedro
> Cc: opal
> Asunto: Re: [Opal] Error OPAL
>
> How do you plot this?
>
> A
> ------
> Dr. sc. math. Andreas (Andy) Adelmann
> Staff Scientist
> Paul Scherrer Institut WBBA/219 CH-5232 Villigen PSI
> Phone Office: xx41 56 310 42 33 Fax: xx41 56 310 31 91
> Phone Home: xx41 62 891 91 44
> -------------------------------------------------------
> Friday: ETH CAB F37 or HPK G 28 +41 44 632 75 22
> ============================================
> The more exotic, the more abstract the knowledge,
> the more profound will be its consequences.
> Leon Lederman
> ============================================
>
> On 9 Feb 2017, at 11:47, Calvo Portela, Pedro <Pedro.Calvo AT ciemat.es<mailto:Pedro.Calvo AT ciemat.es>> wrote:
>
> Dear Andreas
>
> I've include the modification at the Field Solver, and now the error doesn't occur. But the tracking of the particles are absolutely unexpected. I attach two plots of the orbits with 1000 and 999 particles. You could see that the results are complete different.
>
> Best regards
> Pedro
>
> ________________________________
> De: Adelmann Andreas (PSI) [andreas.adelmann AT psi.ch<mailto:andreas.adelmann AT psi.ch>]
> Enviado el: miércoles, 08 de febrero de 2017 21:15
> Para: Calvo Portela, Pedro
> Asunto: Re: [Opal] Error OPAL
>
> Hi Pedro, try to change:
>
>
> FSTYPE=FFT, MX=32, MY=32, MT=64
>
> to
>
> FSTYPE=FFT, MX=16, MY=16, MT=32, ….
>
> You only have 1000 particles and apps. 65k grid cells.
>
> How many cores do you use?
>
> Andreas
>
>
>
> On 31 Jan 2017, at 08:58, Calvo Portela, Pedro <Pedro.Calvo AT ciemat.es<mailto:Pedro.Calvo AT ciemat.es>> wrote:
>
> Dear Andreas.
>
> I'm using the version 1.4.0 of OPAL.
> I share with you the input files in a dropbox folder.
>
> Cheers
> Pedro
>
> ________________________________
> De: Adelmann Andreas (PSI) [andreas.adelmann AT psi.ch<mailto:andreas.adelmann AT psi.ch>]
> Enviado el: viernes, 27 de enero de 2017 23:35
> Para: Calvo Portela, Pedro
> Cc: opal AT lists.psi.ch<mailto:opal AT lists.psi.ch>
> Asunto: Re: [Opal] Error OPAL
>
> Hi Pedro
>
> can you make all the input files available so we can reproduce the problem.
> Which version of OPAL are you using?
> Cheers Andreas
>
> On 27 Jan 2017, at 11:03, Calvo Portela, Pedro <Pedro.Calvo AT ciemat.es<mailto:Pedro.Calvo AT ciemat.es>> wrote:
>
> Dear OPAL users, I write you because we have some problems about the simulation of a big number of particles.
> We simulate without problems our machine with the correct electric and magnetic fields, including the geometry in the simulation. But when we increase the number of particles above 1000, we obtain the following error in the output:
>
> Error> Interpolator::getFieldIter: attempt to access non-local index{[-2147483648:-2147483648:1],[-2147483648:-2147483648:1],[-2147483648:-2147483648:1]} on node 0
> Error> Dumping local owned and allocated domains:
> Error> 0: owned = {[0:31:1],[0:31:1],[0:31:1]}, allocated = {[-1:32:1],[-1:32:1],[-1:32:1]}
> Error> Error occurred for BareField with layout = Domain = {[0:31:1],[0:31:1],[0:31:1]}
> Error> FieldLayoutUsers = 3
> Error> Total number of vnodes = 1
> Error> Local Vnodes = 1
> Error> vnode 0: Node = 0 ; vnode_m = -1 ; Domain = {[0:31:1],[0:31:1],[0:31:1]}
> Error> Remote Vnodes = 0
> Error>
> Error> Calling abort ...
>
> This error don't occur when the number of particles is lower than 1000.
> We have tried to solve this error changing the fieldsolver in the code for a 1000 particles, but the results are completly diferent if we compare with the simulation with a number of particles of 999. I
>
> I will appreciate any suggestion to solve this problem.
> Best Regards
> Pedro Calvo
>
>
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> <orbits_999part_161632.png><orbits_1000part_161632.png>
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