The OPAL Discussion Forum

[Simon Friederich <sifriede AT uni-mainz.de>]

Good evening Dragos,

Yes indeed. I am using python + pandas to convert the fieldmaps.

Using df_reordered=df.sort_values(by=['x','y','z']) results exactly in the order you've mentioned (in the example y=0 as this is the cylindrical 2DDynamic fieldmap)

[In the next step I write the headlines (e.g. 2DDynamics, zmin zmax Nz-1, FREQ, xmin xmax Nx-1) and only the needed columns into the resulting opal-fieldmap file according to the manual]

I hope, that I've not overseen something here. At least for the reference particle I can assume, that it sees the correct field (Ex_ref, Ey_ref, Ez_ref).

Best regards
Simon

Am 11.09.2020 um 18:00 schrieb Dragos Constantin:

Hi Simon,

I supposed you have checked that the points inside the field maps are correctly ordered, e.g. for 3D field maps the z coordinate is the fastest and, y is next , and x is the slowest.

 

Did you try to normalize the field map?

 

Thanks,

Dragos

 

 

Dragos Constantin, PhD
Sr. Research Scientist

 

Varian Medical Systems
3120 Hansen Way, MS G201, Palo Alto, CA 94304 United States
dragos.constantin AT varian.com
T +650.424.5914 | F +650.842.5035
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From: opal-request AT lists.psi.ch <opal-request AT lists.psi.ch> On Behalf Of Simon Friederich
Sent: Friday, September 11, 2020 1:36 AM
To: Adelmann Andreas (PSI) <andreas.adelmann AT psi.ch>
Cc: opal AT lists.psi.ch
Subject: Re: [Opal] DC gun simulation: Unexpected longitudinal phase spaces

 

Good morning Andreas,

Please follow this link to the fieldmaps (named cst2opal_100keV_xyz_3DDynamic.t7 and cst2opal_100keV_xz_2DDynamic.t7)

https://seafile.rlp.net/d/0b482f64c9c84e339dc5/

Best regards,

Simon

Am 11.09.2020 um 10:24 schrieb Adelmann Andreas (PSI):

Hello Simon, I can not see an obvious mistake. Please share the 

field maps then I can have  detailed look at the problem.

 

 

Thanks & 

Cheers A

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Paul Scherrer Institut OHSA/ CH-5232 Villigen PSI
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On 10 Sep 2020, at 15:40, Simon Friederich <sifriede AT uni-mainz.de> wrote:

 

Dear OPAL-Team, I am trying to simulate a DC electron source. I implemented a 2DDynamics fieldmap into OPAL, that I've exported from CST. Furthermore I've set the frequency to 1 Hz as shown in the DC Gun example. Unfortunately the longitudinal phase spaces look unexpected. Here I've plotted the h5-output for the gun simulation as well as a pure drift simulation of a 100keV electron beam (same bunch sizes and parameters but the energy is fixed) as comparison. <flaghcfdkllelgbc.png> One can see a strange saw-tooth like pattern convoluted with another almost trident-like one. This is my emitted gaussian distribution (nothing special, I'd say): distr_gauss:
    DISTRIBUTION,
    TYPE = GAUSS,
    SIGMAR = 0.5e-3, CUTOFFR = 3,
    CUTOFFLONG = 3; distr_debug:
    distr_gauss,
    EMITTED=true,
    SIGMAT = 10.0e-12,
    NBIN = 0,  // This I've varied
    EMISSIONSTEPS=10,  // this I've varied too
    EMISSIONMODEL = NONE; Maybe you see something obvious, that I did wrong? (I've also put my input file in the attachement, the fieldmaps are quite large, if you want them I'll add a seafile link) I've compared the Ez-field of the reference particle. It looks exactly like the one I've exported from CST. (My next idea was to dumb all E-fields and plot this, but this could be a lot of work and might not bring up the source of the problem). And I've also imported a 3DDynamics field, but there is also no difference to be seen (the source has a cylindrical symmetry, so both should work). Best regards and thank you very much as always in advance Simon

-- 

-----------------------------------

Dr. Simon Friederich

Helmholtz-Institut Mainz

Kollaboration B/ACID

Johannes Gutenberg-Universität Mainz

Staudingerweg 18

55128 Mainz, Deutschland

Tel.: +49 (0)6131 39-23160

E-Mail: sifriede AT uni-mainz.de

----------------------------------------

<dc_gun.in>

 

-- 

-----------------------------------

Dr. Simon Friederich

Helmholtz-Institut Mainz

Kollaboration B/ACID

Johannes Gutenberg-Universität Mainz

Staudingerweg 18

55128 Mainz, Deutschland

Tel.: +49 (0)6131 39-23160

E-Mail: sifriede AT uni-mainz.de

----------------------------------------

-- 
-----------------------------------
Dr. Simon Friederich
Helmholtz-Institut Mainz
Kollaboration B/ACID
Johannes Gutenberg-Universität Mainz
Staudingerweg 18
55128 Mainz, Deutschland

Tel.: +49 (0)6131 39-23160
E-Mail: sifriede AT uni-mainz.de
----------------------------------------