Gallery of plots and scripts 1. Synchrotron sources

Synchrotron sources

The images below are produced by \tests\raycing\test_sources.py and by \examples\withRaycing\01_SynchrotronSources\synchrotronSources.py.

Bending magnet

On a transversal screen the image is unlimited horizontally (practically limited by the front end). The energy distribution is red-shifted for off-plane photons. The polarization is primarily horizontal. The off-plane radiation has non-zero projection to the vertical polarization plane.

source total flux horiz. pol. flux vert. pol. flux
using WS
internal xrt

The off-plane radiation is in fact left and right polarized:

source circular polarization rate
using WS
internal xrt

The horizontal phase space projected to a transversal plane at the origin is parabolic:

zero electron beam size σx = 49 µm

Multipole wiggler

The horizontal image size is determined by the parameter K. The energy distribution is red-shifted for off-plane photons. The polarization is primarily horizontal. The off-plane radiation has non-zero projection to the vertical polarization plane.

source total flux horiz. pol. flux vert. pol. flux
using WS
internal xrt

The horizontal longitudinal cross-section reveals a sinusoidal shape of the source. The horizontal phase space projected to the transversal plane at the origin has individual branches for each pole.

zero electron beam size σx = 49 µm

Undulator

The module test_sources has functions for visualization of the angular and energy distributions of the implemented sources in 2D and 3D. This is especially useful for undulators because they have sharp peaks, which requires a proper selection of angular and energy meshes.

The ray traced images of an undulator source (produced by \examples\withRaycing\01_SynchrotronSources\synchrotronSources.py) are feature-rich. The polarization is primarily horizontal. The off-plane radiation has non-zero projection to the vertical polarization plane.

source total flux hor. pol. flux ver. pol. flux deg. of pol.
using Urgent
internal xrt

Custom field undulator

A custom magnetic field can be specified by an Excel file or a column text file. The example below is based on a table supplied by Hamed Tarawneh [Tarawneh]. The idea of introducing quasi-periodicity is to shift the n-th harmonics down in energy relative to the exact n-fold multiple of the 1st harmonic energy. This trick eliminates higher monochromator harmonics that are situated at the exact n-fold energies, which is a safer solution compared to a gas absorption filter.

Compare the harmonic energies (half-maximum position at the higher energy side) of the 3rd harmonic with the triple energy of the 1st harmonic.

[Tarawneh]Quasi-periodic undulator field for ARPES beamline at MAX IV 1.5 GeV ring, (2016) unpublished.

Note

The definition of xyz coordinate system differs for the tabulated field and for xrt screens: z is along the beam direction in the tabulation and as a vertical axis in xrt.

  periodic quasi-periodic
tabulated field
trajectory top view
wide band image and spectrum
1st harmonic image and spectrum
3rd harmonic image and spectrum

For validation, our calculations are compared here with those by Spectra for a particular case — quasi-periodic undulator defined by the same tabulated field, the 3rd harmonic, at E=20.5 eV. Notice again that Spectra provides either a spectrum or a transverse image while xrt can combine both by using colors and brightness. Notice also that on the following pictures the p-polarized flux is only ~3% of the total flux.

  SPECTRA xrt
total flux
p-pol flux