Add DivertorNumberModels enum and refactor i_single_null usage across…

process/core/init.py

@@ -58,6 +58,7 @@
 )
 from process.data_structure.tfcoil_variables import init_tfcoil_variables
 from process.data_structure.times_variables import init_times_variables
+from process.models.build import DivertorNumberModels
 from process.models.stellarator.initialization import st_init
 from process.models.superconductors import (
     SuperconductorMaterial,
@@ -618,8 +619,8 @@ def check_process(inputs, data):  # noqa: ARG001
                 "REINKE IMPURITY MODEL: The Martin LH threshold scale is not being used and is recommended for the Reinke model",
                 stacklevel=2,
             )
-
-    if data_structure.physics_variables.i_single_null == 0:
+    i_single_null = DivertorNumberModels(data_structure.physics_variables.i_single_null)
+    if i_single_null == DivertorNumberModels.DOUBLE_NULL:
         data_structure.divertor_variables.n_divertors = 2
         data_structure.build_variables.dz_fw_plasma_gap = (
             data_structure.build_variables.dz_xpoint_divertor
@@ -631,7 +632,7 @@ def check_process(inputs, data):  # noqa: ARG001
             data_structure.build_variables.dz_vv_lower
         )
         warn("Double-null: Upper vertical build forced to match lower", stacklevel=2)
-    else:  # i_single_null == 1
+    else:  # i_single_null == DivertorNumberModels.SINGLE_NULL
         data_structure.divertor_variables.n_divertors = 1
 
     #  Tight aspect ratio options (ST)
@@ -736,7 +737,7 @@ def check_process(inputs, data):  # noqa: ARG001
             )
 
         # Check if a single null divertor is used in double null machine
-        if data_structure.physics_variables.i_single_null == 0 and (
+        if i_single_null == DivertorNumberModels.DOUBLE_NULL and (
             data_structure.physics_variables.f_p_div_lower in {1.0, 0.0}
         ):
             warn("Operating with a single null in a double null machine", stacklevel=2)
@@ -818,7 +819,7 @@ def check_process(inputs, data):  # noqa: ARG001
             raise ProcessValidationError(
                 "More than 2 divertor coils (i_pf_location = 2) is not a valid configuration"
             )
-        if data_structure.physics_variables.i_single_null == 1 and j < 2:
+        if i_single_null == DivertorNumberModels.SINGLE_NULL and j < 2:
             raise ProcessValidationError(
                 "If i_single_null=1, use 2 individual divertor coils (i_pf_location = 2, 2; n_pf_coils_in_group = 1, 1)"
             )

process/models/build.py

@@ -28,6 +28,13 @@
 logger = logging.getLogger(__name__)
 
 
+class DivertorNumberModels(IntEnum):
+    """Enum for divertor number models. `i_single_null` is the index for this enum."""
+
+    DOUBLE_NULL = 0
+    SINGLE_NULL = 1
+
+
 class FwBlktVVShape(IntEnum):
     """Enum for first wall, blanket, and vacuum vessel shape options."""
 
@@ -178,7 +185,8 @@ def calculate_vertical_build(self, output: bool):
                 physics_variables.i_single_null,
             )
 
-            if physics_variables.i_single_null == 0:
+            i_single_null = DivertorNumberModels(physics_variables.i_single_null)
+            if i_single_null == DivertorNumberModels.DOUBLE_NULL:
                 po.ocmmnt(self.outfile, "Double null case")
 
                 # Start at the top and work down.
@@ -810,7 +818,7 @@ def calculate_vertical_build(self, output: bool):
         )
 
         #  Vertical locations of divertor coils
-        if physics_variables.i_single_null == 0:
+        if i_single_null == DivertorNumberModels.DOUBLE_NULL:
             build_variables.z_tf_top = (
                 build_variables.z_tf_inside_half + build_variables.dr_tf_inboard
             )
@@ -1691,7 +1699,8 @@ def calculate_radial_build(self, output: bool):
             build_variables.dr_blkt_inboard + build_variables.dr_blkt_outboard
         )
 
-        if physics_variables.i_single_null == 1:
+        i_single_null = DivertorNumberModels(physics_variables.i_single_null)
+        if i_single_null == DivertorNumberModels.SINGLE_NULL:
             #  Check if build_variables.dz_fw_plasma_gap has been set too small
             build_variables.dz_fw_plasma_gap = max(
                 0.5e0

process/models/divertor.py

@@ -11,6 +11,7 @@
 from process.data_structure import fwbs_variables as fwbs
 from process.data_structure import physics_variables as pv
 from process.data_structure import tfcoil_variables as tfv
+from process.models.build import DivertorNumberModels
 
 
 class Divertor(Model):
@@ -181,10 +182,10 @@ def divtart(
         #  Total divertor area
 
         # Single null case
-        if i_single_null == 1:
+        if i_single_null == DivertorNumberModels.SINGLE_NULL:
             areadv = a1 + a2 + a3
         # Double null case
-        elif i_single_null == 0:
+        elif i_single_null == DivertorNumberModels.DOUBLE_NULL:
             areadv = 2.0 * (a1 + a2 + a3)
 
         if dv.i_div_heat_load == 1:

process/models/geometry/plasma.py

@@ -7,6 +7,7 @@
 
 import numpy as np
 
+from process.models.build import DivertorNumberModels
 from process.models.physics.plasma_geometry import PlasmaShapeModelType
 
 
@@ -77,7 +78,7 @@ def plasma_geometry(
         theta2 = np.arcsin((kappa * rminor) / r2)
         inang = 1.0 / r1
         outang = 1.5 / r2
-        if i_single_null == 0:
+        if i_single_null == DivertorNumberModels.DOUBLE_NULL:
             angs1 = np.linspace(
                 -(inang + theta1) + np.pi, (inang + theta1) + np.pi, 500, endpoint=True
             )

process/models/tfcoil/base.py

@@ -26,6 +26,7 @@
     tfcoil_variables,
 )
 from process.data_structure import build_variables as bv
+from process.models.build import DivertorNumberModels
 from process.models.superconductors import SuperconductorModel
 
 if TYPE_CHECKING:
@@ -498,7 +499,7 @@ def tf_coil_shape_inner(
             r_tf_arc[3] = r_tf_arc[1]
             r_tf_arc[4] = r_tf_arc[0]
 
-            if i_single_null == 0:
+            if i_single_null == DivertorNumberModels.DOUBLE_NULL:
                 z_tf_arc[0] = FSTRAIGHT * z_tf_inside_half
                 z_tf_arc[1] = z_tf_inside_half
                 z_tf_arc[2] = 0