# this example shows users how to make a mesh source using a cylindrical mesh and a source term for each voxel.
# this is a minimal example but a more realistic example could use the voxel location to look up properties
# of the plasma at each coordinate and customize the source energy and strength at each mesh voxel location
from pathlib import Path
import numpy as np
import openmc
from openmc_source_plotter import plot_source_position
# 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'
# making a minimal geometry
sphere_surf_1 = openmc.Sphere(r=2000)
sphere_cell_1 = openmc.Cell(region=-sphere_surf_1)
my_geometry = openmc.Geometry([sphere_cell_1])
# creating the mesh used for the mesh source
cylindrical_mesh = openmc.CylindricalMesh.from_domain(
my_geometry, # the corners of the mesh are being set automatically to surround the geometry
dimension=[10,10,10]
)
# empty list that will contain one source for each mesh voxel
all_sources = []
for i in cylindrical_mesh.indices:
mesh_index = (i[0]-1, i[1]-1, i[2]-1)
# this minimal example sets the same source for each voxel
# to create a realistic plasma source the mesh centroid could be used to
# find source strength, temperature and make a location specific source
# a function could be called that returns the temperature and relative source
# strength for each x,y,z or r, phi, z location
# voxel centroid can be obtained like this
# centroid = cylindrical_mesh.centroids[mesh_index]
# voxel cylindrical_coords (z, phi, r) can be obtained like this
cylindrical_coords = cylindrical_mesh.vertices_cylindrical[mesh_index]
volume = cylindrical_mesh.volumes[mesh_index]
# making a source for each voxel
my_source = openmc.IndependentSource()
my_source.energy = openmc.stats.Discrete([14.1e6], [1])
my_source.angle = openmc.stats.Isotropic()
if cylindrical_coords[2] > 1000: # filtering out sources below radius of 1000
my_source.strength = volume # uniform source
else:
my_source.strength = 0
all_sources.append(my_source)
# creating the mesh source from the mesh and the list of sources
# the main difference between MeshSpatial (previous example) and MeshSource is that in
# MeshSpatial each mesh element has the same source with potentially a different
# strength while in MeshSource the elements can have a different source.
# Having a different source would allow a different energy distribution and therefore
# MeshSources are useful for shut down dose rate simulations where each active element
# results in a different photon emission
mesh_source = openmc.MeshSource(
mesh=cylindrical_mesh,
sources=np.array(all_sources).reshape(cylindrical_mesh.dimension)
)
# Update all element source strengths such that they sum to 1.0.
# this makes post processing the results easier if the total source strength is 1
mesh_source.normalize_source_strengths()
# plotting the mesh source
plot = plot_source_position([mesh_source], n_samples=10000)
plot.show()
