Wiggler Simulation using SRW

[lyp114514]

This is my first time using SRW. I would like to simulate the far-field radiation flux for a Wiggler insertion device. Initially, I based my work on Example 6, modifying the parameters of the Undulator to achieve a large K value. However, the simulated flux turned out to be zero. I would like to ask whether SRW provides dedicated functions specifically designed for Wiggler simulations (I have not been able to find any). If such functions exist, could you kindly point me to an example that I could refer to in order to meet my simulation requirements? Below are the parameters of the electron beam and the insertion device that I used.

#***********Undulator
harmB = SRWLMagFldH()
harmB.n = 1
harmB.h_or_v = 'v'
harmB.B = 1.8
und = SRWLMagFldU([harmB])
und.per = 1.392
und.nPer = 1
magFldCnt = SRWLMagFldC([und], array('d', [0]), array('d', [0]), array('d', [0]))

#***********Electron Beam
eBeam = SRWLPartBeam()
eBeam.partStatMom1.gamma = 2.5/0.51099890221e-03
eBeam.Iavg = 0.25
eBeam.partStatMom1.x = 0.
eBeam.partStatMom1.y = 0.
eBeam.partStatMom1.z = 0.
eBeam.partStatMom1.xp = 0
eBeam.partStatMom1.yp = 0
sigEperE = 7e-4
sigX = 1.026e-3
sigXp = 0.175e-3
sigY = 0.957e-3
sigYp = 0.081e-3
eBeam.arStatMom2[0] = sigXsigX
eBeam.arStatMom2[1] = 0
eBeam.arStatMom2[2] = sigXpsigXp
eBeam.arStatMom2[3] = sigYsigY
eBeam.arStatMom2[4] = 0
eBeam.arStatMom2[5] = sigYpsigYp
eBeam.arStatMom2[10] = sigEperE*sigEperE

[ochubar]

You are probably trying to calculate wiggler spectrum using this method:
srwl.CalcStokesUR(stkF, eBeam, und, arPrecF)
(?)
If so, please note that this is an approximate method, developed for undulators. It can be used to get some approximate information about wiggler spectra, but for this one has to define precision parameters accordingly (arPrecF), in particular this one (in line ~68):
arPrecF[1] = 21 #final UR harmonic to take into account
For a wiggler, this number may need to be very large (100s or even 1000s - you can estimate this yourself from the fundamental photon energy). The calculation will be slow; you can test by gradually increasing the spectral range (stkF.mesh.eFin value).

In SRW for Igor Pro, there are several other (also approximate) methods available for wigglers. You can also use bending magnet magnet spectral calculations in many cases.
When I need to calculate wiggler emission and wavefront propagation ~accurately, I try to use the general method for electric field calculation (srwl.CalcElecFieldSR) and integrate over the phase space volume of electron beam. This is even more tricky, but doable.

[lyp114514]

Thank you for your suggestion. Following a similar approach to Example 13, I used a bending magnet instead of a Wiggler, and the situation has improved. Attachment 1(Left figure) shows the spectral distribution obtained from my SRW simulation, while Attachment 2(Right figure) shows the synchrotron radiation spectrum provided by the experimental beamline. It can be seen that although the two spectra exhibit similar trends, there remains a discrepancy in magnitude. Attachment 3 is my code. I would like to know whether there are any aspects of the simulation that could still be optimized?

BSRF_4W1_sim.py