FBPIC does not start with mode m=0 about fbpic HOT 2 OPEN

Dear @Sculpdure, the parameter Nm refers to the total number of azimuthal modes that are simulated. For Nm = 1, only the mode m=0 is simulated.

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Dear Manuel,
Thanks a lot for this explanation. So mode = Nm -1.

FBPIC is a wonderful and super fast LWFA 2D code!
OpenPMD gives a super efficient way to analyse/visualize data once we get used to it.
The thing is I have difficulties in finding detailed information on the diagnostics.

The tutorials did not work for me over the last weeks but I could reach it lately. I learned a lot. I figured out that 'rho' isn’t macroparticles density but is actually charge density in C/m-3 (openPMD don’t give units).
I still have questions:

• What provides ParticleChargeDensityDiagnostic() in addition to ParticleDiagnostic()?
  I ask because I could have access to electrons data (position and momentum per mc)

• What is “w” called weight?
  Is it number of particles per cell (electrons) What unit?
  I found that some guys calculate electron charge from it:
  x,z,w = ts.get_particle(['x', 'z', 'w'], iteration=ts.iterations[-1])
  Does it get the particles in the (x,z) plane only?
  np.sum(w) * 1.602e-19 # calculate the charge, in C

print('weight dim', w.shape) gives :(339265,)
I’m very confused.
get_particle(t=ts.t[iter_nb], var_list=['w'],plot=True, vmax=1e7), gives this graph:
(What is vmax?)

• What does “ ts.get_charge” calculate from LpaDiagnostics?
  I got exact same values (in C) from get.charge and from np.sum(w).

• How do we get the list of diagnostics from LpaDiagnostics (similarly as laser diagnostics)?
  I know: get_charge, get_current, get_spectrum.

Thank you for your time.
Sincerely, Fred

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