wave caculation and coherence analysis issue

[kklmn]

wave caculation and coherence analysis issue

[kklmn]

plot.field3D is a stack of 2D fields per electron (repeat). It has a shape (repeats, nx, ny) and is supposed to be fed to xrt.backends.raycing.coherence.calc_eigen_modes_PCA().

Filament beam is a single electron emission, where the electron has random lateral and angular shifts within the given emittance distributions ε_x and ε_z and an energy shift within the given energy spread. If filamentBeam is False, each ray in the beam has its own set of those random samples; you can't do wave propagation then. If you propagate in rays then yes, the results with and without filamentBeam will be equal at many repeats.

Please also read the section Coherence analysis and related plotting. It refers to SoftiMAX examples and also to a test ...\tests\raycing\test_coherent_fraction_stack.py that you may want to scrutinize.

[yangfg-bsrf]

I got it, yes, I found that if the repeats is as large as enough, 1000 in my case. The coherence feature is same with the theoretical value.
In addtion, I found some examples use a inner repeat inside the run_processm. For the filamentBeam, I found that only one spot source was shown for this series of repeated computation, eventhough I did not set accuBeam. I dont get the meanning of this inner-repeat, would you please comment it for me? thanks

[kklmn]

This is an attempt to optimize wave propagation. Frequently, only the last few diffraction events need more samples (repeats) whereas the intermediate wave distributions may remain at lower quality. By increasing the internal repeats and decreasing the global ones you may save some computation time with almost the same quality at the final screen. In reality, this saving is little, so I typically go without internal repeats.

[yangfg-bsrf]

thanks for your suggestion.