improved energy distribution

src/openmc_plasma_source/fuel_types.py

@@ -1,37 +1,92 @@
-"""fuel_types.py
+import NeSST as nst
+import numpy as np
+import openmc
 
-Defines dictionary for determining mean energy and mass of reactants
-for a given fusion fuel type.
-"""
+def get_neutron_energy_distribution(
+        ion_temperature: float,
+        fuel: dict = {'D':0.5, 'T':0.5},
+) -> openmc.stats.Discrete:
+    """Finds the energy distribution
 
+    Parameters
+    ----------
+    ion_temperature : float
+        temperature of plasma ions in eV
+    fuel : dict
+        isotopes as keys and atom fractions as values
 
-class Fuel:
-    def __init__(self, mean_energy, mass_of_reactants):
-        self.mean_energy = mean_energy
-        self.mass_of_reactants = mass_of_reactants
+    Returns
+    -------
+    openmc.stats.Discrete
+        energy distribution
+    """
 
-    @property
-    def mean_energy(self):
-        return self._mean_energy
+    ion_temperature = ion_temperature / 1e3  # convert eV to keV
 
-    @mean_energy.setter
-    def mean_energy(self, value):
-        if value <= 0:
-            raise (ValueError("mean_energy needs to be strictly positive"))
-        self._mean_energy = value
+    sum_fuel_isotopes = sum(fuel.values())
+    if sum_fuel_isotopes > 1.:
+        raise ValueError(f'isotope fractions within the fuel must sum to be below 1. Not {sum_fuel_isotopes}')
 
-    @property
-    def mass_of_reactants(self):
-        return self._mass_of_reactants
+    if sum_fuel_isotopes < 0.:
+        raise ValueError(f'isotope must sum to be above 0. Not {sum_fuel_isotopes}')
 
-    @mass_of_reactants.setter
-    def mass_of_reactants(self, value):
-        if value <= 0:
-            raise (ValueError("mass_of_reactants needs to be strictly positive"))
-        self._mass_of_reactants = value
+    for k, v in fuel.dict:
+        if k not in ['D', 'T']:
+            raise ValueError(f'Fuel dictionary keys must be either "D" or "T" not "{k}".')
+        if v < 0:
+            raise ValueError(f'Fuel dictionary values must be above 0 not "{k}".')
+        if v > 1:
+            raise ValueError(f'Fuel dictionary values must be below 1 not "{k}".')
 
+    #Set atomic fraction of D and T in scattering medium and source
+    if 'D' in fuel.keys():
+        nst.frac_D_default = fuel['D']
+        max_energy_mev=5
+    else:
+        nst.frac_D_default = 0
 
-fuel_types = {
-    "DD": Fuel(mean_energy=2450000.0, mass_of_reactants=4),
-    "DT": Fuel(mean_energy=14080000.0, mass_of_reactants=5),
-}
+    if 'T' in fuel.keys():
+        nst.frac_T_default = fuel['T']
+        max_energy_mev=12
+    else:
+        nst.frac_T_default = 0
+
+    if 'T' in fuel.keys() and 'D' in fuel.keys():
+        max_energy_mev=20
+
+    # 1.0 neutron yield, all reactions scaled by this value
+    num_of_vals = 500
+    # single grid for DT, DD and TT grid
+    E_pspec = np.linspace(0, max_energy_mev, num_of_vals)  # accepts MeV units
+
+    dNdE_DT_DD_TT = np.zeros(num_of_vals)
+    if 'D' in fuel.keys() and 'T' in fuel.keys():
+        DTmean, DTvar = nst.DTprimspecmoments(ion_temperature)
+        DDmean, DDvar = nst.DDprimspecmoments(ion_temperature)
+
+        Y_DT = 1.0
+        Y_DD = nst.yield_from_dt_yield_ratio("dd", Y_DT, ion_temperature)
+        Y_TT = nst.yield_from_dt_yield_ratio("tt", Y_DT, ion_temperature)
+
+        dNdE_DT = Y_DT * nst.Qb(E_pspec, DTmean, DTvar)  # Brysk shape i.e. Gaussian
+        dNdE_DD = Y_DD * nst.Qb(E_pspec, DDmean, DDvar)  # Brysk shape i.e. Gaussian
+        dNdE_TT = Y_TT * nst.dNdE_TT(E_pspec, ion_temperature)
+        dNdE_DT_DD_TT= dNdE_DT + dNdE_DD + dNdE_TT
+
+    if 'D' in fuel.keys() and 'T' not in fuel.keys():
+        DTmean, DTvar = nst.DTprimspecmoments(ion_temperature)
+        DDmean, DDvar = nst.DDprimspecmoments(ion_temperature)
+
+        Y_DD = 1.0
+
+        dNdE_DD = Y_DD * nst.Qb(E_pspec, DDmean, DDvar)  # Brysk shape i.e. Gaussian
+        dNdE_DT_DD_TT= dNdE_DD
+
+    if 'D' not in fuel.keys() and 'T' in fuel.keys():
+
+        Y_TT = 1.0
+
+        dNdE_TT = Y_TT * nst.dNdE_TT(E_pspec, ion_temperature)
+        dNdE_DT_DD_TT= dNdE_TT
+
+    return openmc.stats.Discrete(E_pspec * 1e6, dNdE_DT_DD_TT)

src/openmc_plasma_source/point_source.py

@@ -1,7 +1,7 @@
 import openmc
 from typing import Tuple
 
-from .fuel_types import fuel_types
+from .fuel_types import get_neutron_energy_distribution
 
 
 class FusionPointSource(openmc.IndependentSource):
@@ -21,7 +21,7 @@ def __init__(
         self,
         coordinate: Tuple[float, float, float] = (0.0, 0.0, 0.0),
         temperature: float = 20000.0,
-        fuel: str = "DT",
+        fuel: dict = {"D": 0.5, "T": 0.5},
     ):
         # Set local attributes
         self.coordinate = coordinate
@@ -35,11 +35,7 @@ def __init__(
         # performed after the super init as these are Source attributes
         self.space = openmc.stats.Point(self.coordinate)
         self.angle = openmc.stats.Isotropic()
-        self.energy = openmc.stats.muir(
-            e0=self.fuel.mean_energy,
-            m_rat=self.fuel.mass_of_reactants,
-            kt=self.temperature,
-        )
+        self.energy = get_neutron_energy_distribution(ion_temperature=temperature, fuel=fuel)
 
     @property
     def coordinate(self):

src/openmc_plasma_source/ring_source.py

@@ -2,7 +2,7 @@
 import numpy as np
 from typing import Tuple
 
-from .fuel_types import fuel_types
+from .fuel_types import get_neutron_energy_distribution
 
 
 class FusionRingSource(openmc.IndependentSource):
@@ -25,15 +25,14 @@ def __init__(
         angles: Tuple[float, float] = (0, 2 * np.pi),
         z_placement: float = 0,
         temperature: float = 20000.0,
-        fuel: str = "DT",
+        fuel: dict = {"D": 0.5, "T": 0.5},
     ):
         # Set local attributes
         self.radius = radius
         self.angles = angles
         self.z_placement = z_placement
         self.temperature = temperature
-        self.fuel_type = fuel
-        self.fuel = fuel_types[self.fuel_type]
+        self.fuel = fuel
 
         # Call init for openmc.Source
         super().__init__()
@@ -46,11 +45,7 @@ def __init__(
             origin=(0.0, 0.0, 0.0),
         )
         self.angle = openmc.stats.Isotropic()
-        self.energy = openmc.stats.muir(
-            e0=self.fuel.mean_energy,
-            m_rat=self.fuel.mass_of_reactants,
-            kt=self.temperature,
-        )
+        self.energy = get_neutron_energy_distribution(ion_temperature=temperature, fuel=fuel)
 
     @property
     def radius(self):

src/openmc_plasma_source/tokamak_source.py

@@ -2,6 +2,8 @@
 import numpy as np
 from typing import Tuple
 
+from .fuel_types import get_neutron_energy_distribution
+
 
 class TokamakSource:
     """Plasma neutron source sampling.
@@ -68,6 +70,7 @@ def __init__(
         shafranov_factor: float,
         angles: Tuple[float, float] = (0, 2 * np.pi),
         sample_size: int = 1000,
+        fuel: dict = {"D": 0.5, "T": 0.5},
     ) -> None:
         # Assign attributes
         self.major_radius = major_radius
@@ -88,6 +91,7 @@ def __init__(
         self.shafranov_factor = shafranov_factor
         self.angles = angles
         self.sample_size = sample_size
+        self.fuel = fuel
 
         # Perform sanity checks for inputs not caught by properties
         if self.minor_radius >= self.major_radius:
@@ -385,9 +389,7 @@ def make_openmc_sources(self):
             )
 
             my_source.angle = openmc.stats.Isotropic()
-            my_source.energy = openmc.stats.muir(
-                e0=14080000.0, m_rat=5.0, kt=self.temperatures[i]
-            )
+            my_source.energy = get_neutron_energy_distribution(ion_temperature=self.temperature[i], fuel=self.fuel)
 
             # the strength of the source (its probability) is given by
             # self.strengths