pySRU

Synchrotron Radiation Undulator emission in python

Main development website: https://github.com/oasys-kit/pySRU

A toolbox to calculate the emission of radiation by undulators in storage rings.

This software library implements formulas to calculate the emission of radiation by undulators in storage rings, and more generally, the emission of a relativistic electron in an arbitrary magnetic field.

The software is written in pure python, using standard packages as numpy and scipy. It uses matplotlib for plots, but it is not required for calculations.

License

This code is relased under the MIT license as detailed in the LICENSE file.

Installation

To build the library for python use, just use the pip install . in the pySRU directory. It is also available in http://pypi.python.org/pypi/pySRU/: pip install pySRU

Example

The file Simulations.py contains a number of simulations. For example the following code created the emission of an undulator like in fig 2.5 of the X-ray Data Booklet (http://xdb.lbl.gov/Section2/Sec_2-1.html)

This piece of Python code shows how the library can be used via its python binding.

from pySRU.ElectronBeam import ElectronBeam
from pySRU.MagneticStructureUndulatorPlane import MagneticStructureUndulatorPlane as Undulator
from pySRU.Simulation import create_simulation
from pySRU.TrajectoryFactory import TRAJECTORY_METHOD_ANALYTIC,TRAJECTORY_METHOD_ODE
from pySRU.RadiationFactory import RADIATION_METHOD_NEAR_FIELD, RADIATION_METHOD_APPROX_FARFIELD

print("======================================================================")
print("======      Undulator from X-ray data booklet                  =======")
print("====== fig 2.5 in  http://xdb.lbl.gov/Section2/Sec_2-1.html    =======")
print("======================================================================")

# note that the flux in the reference fig 2.6 is a factor 10 smaller than the calculated here.
# This factor comes from the units:
#     here: phot / s  / A / 0.1%bw / (mrad)^2
#     ref : phot / s  / A /   1%bw / (0.1 mrad)^2

undulator_test = Undulator(K=1.87, period_length=0.035, length=0.035 * 14)
electron_beam_test = ElectronBeam(Electron_energy=1.3, I_current=1.0)

simulation_test = create_simulation(magnetic_structure=undulator_test,electron_beam=electron_beam_test,
                    magnetic_field=None, photon_energy=None,
                    traj_method=TRAJECTORY_METHOD_ANALYTIC,Nb_pts_trajectory=None,
                    rad_method=RADIATION_METHOD_APPROX_FARFIELD, Nb_pts_radiation=101,
                    initial_condition=None, distance=None,XY_are_list=False,X=None,Y=None)


# simulation_test.print_parameters()

# simulation_test.trajectory.plot_3D(title="Electron Trajectory")

simulation_test.radiation.plot(title="Flux in far field vs angle")

Result link: https://github.com/SophieTh/und_Sophie_2016/blob/master/doc/radiation_xraybooklet.jpeg

Documentation

For using pySRU, start with prepared simulations in Simulation.py

A comparison of the pySRU results with other codes can be found at: https://github.com/oasys-kit/pySRU/blob/master/doc/pySRU_comparison.pdf

A document including the formulas and algorithms used is: https://github.com/oasys-kit/pySRU/blob/master/doc/report_thery_m1.pdf

Testing

• Travis CI status:

To do

• Quicker calculation of intensity spectrum
• Implement simplified formulas for calculating power density
• Add electron emittance via convolutions
• Implement the pi polarization
• Extend to helical undulators