Hi Tadzio,

you are probably talking about the virtual point of the "maximum" of the
laser that is for a long laser pulse further in the middle of the
simulation.

That is correct, we define the "start the moving window" point from a
photon that starts moving at the lower end of the simulation to be sure
no information (field solver) is cut off on the upper end that
originated at the lower end (laser pulse).

Nevertheless, independent of the pulse length you will notice that the
window starts moving at the same time step (if number of cells and grid
cells are unchanged).

See also the documentation in the param file:

https://github.com/ComputationalRadiationPhysics/picongpu/blob/ac82b4c96d5659380042b0e61f14092961e36120/src/picongpu/include/simulation_defines/param/gridConfig.param#L60-L70


Best,
Axel

On 13.08.2015 12:30, René Widera wrote:
> Dear Tadzio,
>
> can you please post your simulation output from the file "output" or
> "stdout"
>
> best,
> René
>
> Am 13. August 2015 19:40:25 MESZ, schrieb Tadzio Levato
> <tadzio.levato@eli-beams.eu>:
>
>     Dear René,
>
>     thanks!
>
>     About the starting point:
>     I see that it change increasing the laser pulse lenght, its normal ?
>     In particular using a 5fs pulse, it start aroun 0.9 of the sim box (lwfa
>     example),
>     increasing to 20fs, the starting point decrease to about 0.4.
>
>     Cheers
>     Tadzio
>
>
>     Il 13/08/2015 15:35, René Widera ha scritto:
>
>         Dear Tadzo,
>
>         currently there is no option to set the moving window velocity
>         :-( see
>         open issu:
>         https://github.com/ComputationalRadiationPhysics/picongpu/issues/377
>         )
>
>         The moving window point can changed in `gridConfig.param`
>         (https://github.com/ComputationalRadiationPhysics/picongpu/blob/master/src/picongpu/include/simulation_defines/param/gridConfig.param#L70
>
>         )
>
>         best,
>
>         René
>
>         On 13.08.2015 15:30, Tadzio Levato wrote:
>
>             Hi all,
>
>             how to choose the moving window starting point and the
>             velocity of the
>             window?
>
>             Cheers
>             Tadzio
>
>
>
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--

Axel Huebl
Phone +49 351 260 3582
https://www.hzdr.de/crp
Computational Radiation Physics
Laser Particle Acceleration Division
Helmholtz-Zentrum Dresden - Rossendorf e.V.

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