Re: [ibsimu-forum] Too small step size exception

[Ornella L. <orn...@ln...>]

Dear Taneli,

Thank you for your answer.

After 10 iteration the meniscus is quite convex.

I'll have to review the electrodes configuration.

Regards.

Ornella


Il 16/04/2019 19:57, Kalvas, Taneli ha scritto:
> Dear Ornella,
>
> This looks ok. Please note that you do not define a beam with 880 uA, but you define a plasma flux which corresponds to 880 uA for a r=3 mm aperture. This would be exactly a beam with 880 uA current if there was no focusing effects before the collimating plasma electrode. But as you are calculating a plasma extraction system the plasma meniscus is formed and there are electric fields in the plasma sheath which affect the current being extracted. If you have a convex shape in the plasma meniscus there will be a focusing force at the sheath region, which increases the extracted current. This is what is happening here.
>
> Taneli
>
> --
> Taneli Kalvas
> Ph.D., Senior researcher
> Department of Physics, room FL114
> P.O. Box 35 (YFL)
> 40014 University of Jyväskylä, Finland
> Mobile: +358-44-314-1602
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>
> ________________________________________
> From: Ornella Leonardi <orn...@ln...>
> Sent: Tuesday, April 16, 2019 7:21:05 PM
> To: ibs...@li...
> Subject: [ibsimu-forum] Too small step size exception
>
> Dear all,
> I’m working with IBSimu from some weeks.
> I’m running a simulation on a positive Ion Source.
> I have a Mode_CYL geometry where I add a pexp_plasma at -3mm from the plasma electrode.
> The simulation converges and complete all iterations, but on the console I see bad value concerning total beam current.
> I add a beam of 880 micro Amp and during the iterations I get a total current on boundary 2 greater than the initial one.
> At  Major cycle 0 I can read "Total beam current 0.00679A"
> I report the total current (@boundary 2) trend vs. # interaction:
> 0) 0.000946 A
> 1) 0.000974 A
> 2) 0.000969A
> 3) 0.000975 A
> 4) 0.001176 A
> 5) 0.000961A
> 6) 0.001096 A
> 7) 0.00103 A
> 8) 0.001031 A
> 9) 0.001027 A
> 10)0.001035A
>
> What am I doing wrong?
> I attached my source code to allow you to check if I made any mistakes.
> Thanks in advance.
> Regards.
> Ornella
>
> --
>
> Ornella Leonardi, Ph.D
>
> Istituto Nazionale di Fisica Nucleare
> Laboratori Nazionali del Sud
> Via S. Sofia 62
> 95123 Catania (Italy)
> office:   +39 095 542642
> e-mail:   orn...@ln...<mailto:orn...@ln...>
>
-- 

Ornella Leonardi, Ph.D

Istituto Nazionale di Fisica Nucleare
Laboratori Nazionali del Sud
Via S. Sofia 62
95123 Catania (Italy)
office:   +39 095 542642
e-mail:   orn...@ln...