filter on particles appears to be asymmetric

[PrometheusPi]

When viewing particles (visualized from 0 to 1) the appearing structure looks asymmetric in x.

Is it possible that the filter applied to which particles are actually visualized is

• depending on just one vector component of the momentum
• is depending on the sign of the quantity (and not its absolute value (see issue #85 on why this could not be tested with a suitable functor)
  • or both ?

A plot showing this asymmetry is given below

The pink particles show:

• an ejection front only on the bottom - (due to symmetry reasons they should be in both directions)
• an asymmetric (higher energy) region inside the laser - (due to the rotational symetry of the laser and its linear polarization this should be approximately mirror-symmetric on the k-B plane)

This might be a unsuited default setup for particles - but with the missing lengthfunctor this can not be avoided.

[ax3l]

You should post the functor chain you are using as well together with the transfer function settings.

[PrometheusPi]

as mentioned - the simulation crashed which causes the client to shut down the simulation viewer and thus the functor chain 😞 - I can not exactly recreate the functor chain. It was something like

length(mul(2))
# or
mul(2) length

Either way - it should not crash.

[ax3l]

By default, if a "vector" value hits the end of the functor chain it's ".x()" value will be taken.

Functor chains are written as follows:

mul(2) | length

with a | pipe in between.

There is no need for

length | mul(x)

as the last "stretch" can simply be set in the transfer function.

I can not exactly recreate the functor chain.

I do not understand what this means. You don't remember what you typed in the textbox?

[PrometheusPi]

@ax3l : Yes I did apply the functor chain this morning after sitting the live sim for 12 hours - I do not remember the exact syntax. The green "OK" next to the pipeline suggested a syntax sanity check which allows to experiment and does not cause a total crash of the PIConGPU simulation.

As already mentioned via mail by @FelixTUD and as written above by @ax3l the correct absolute momentum approach would be:

length | mul(2.2) 

@FelixTUD can this be set as default for particle chains?

[ax3l]

I do not remember the exact syntax.

I understand your frustration, but how shall people help you if you can't give a reproducer? ;-)

No, there are unfortunately little defaults you can set. In the past, we used an experimental command-line tcp client such as iltis (storing and re-playing your last settings) or one might be able to hack it directly in the code.

For presentations, just connect two web clients, control and prepare it from one and let the main presentation PC just connect as well.