Part 2 - Ring source plotting

This python notebook shows users how to make a simple ring source in OpenMC and plot the position of source particles.

We will make use of the CylindricalIndependent source as described in the docs https://docs.openmc.org/en/stable/pythonapi/generated/openmc.stats.CylindricalIndependent.html

The CylindricalIndependent source can make makes a ring shaped source with the corect inputs.

• The r value (distribution of radius values)

• The phi value (distribution of azimuthal angle values)

• The z value (distribution of z values on the z axis)

Each of these inputs must be a univariate probability disitribution.

OpenMC has several built in distributions for popular distributions such as Normal, Maxwell and others.

See the full list here https://docs.openmc.org/en/stable/pythonapi/stats.html#univariate-probability-distributions

In this example we are going to make use of the Uniform disitrbution by feel free to tinker with the differnt distributions an make your own source.

First import OpenMC and configure the nuclear data path

import openmc
from pathlib import Path
# Setting the cross section path to the correct location in the docker image.
# If you are running this outside the docker image you will have to change this path to your local cross section path.
openmc.config['cross_sections'] = Path.home() / 'nuclear_data' / 'cross_sections.xml'

# This package provides simple source plotting functions
# for more details here is a link to the package repository
# https://github.com/fusion-energy/openmc_source_plotter
from openmc_source_plotter import plot_source_position

# initialises a new source object
my_source = openmc.IndependentSource()

# the distribution of radius is just a single value
radius = openmc.stats.Discrete([10], [1])

# the distribution of source z values is just a single value
z_values = openmc.stats.Discrete([0], [1])

# the distribution of source azimuthal angles values is a uniform distribution between 0 and 2 Pi
angle = openmc.stats.Uniform(a=0., b=2* 3.14159265359)

# this makes the ring source using the three distributions and a radius
my_source.space = openmc.stats.CylindricalIndependent(r=radius, phi=angle, z=z_values, origin=(0.0, 0.0, 0.0))

# sets the direction to isotropic
my_source.angle = openmc.stats.Isotropic()

# sets the energy distribution to a Muir distribution neutrons
my_source.energy = openmc.stats.muir(e0=14080000.0, m_rat=5.0, kt=20000.0)

this next code block runs openmc and creates a file containing information on the initial particles. The position information is the extracted and plotted

plot_source_position(my_source)

This is closer to looking like a plasma compared to a point source but the distribution of spatial distribution can be improved in the next task

# these plotting methods can also be run if you are interested in energy or direction
# they will need importing from the openmc_source_plotter package
# plot_source_energy(my_source)
# plot_source_direction(my_source)

For convenience a plasma source package has been made that wraps openmc.IndependentSource and provides easy creation of ring (and other) fusion sources. fusion-energy/openmc-plasma-source you could try plotting the position of this source