From 8be1b337b66eef413536dfc86483da1c00c7c68f Mon Sep 17 00:00:00 2001
From: mn3981 <christopher.ashe@ukaea.uk>
Date: Thu, 9 Jul 2026 09:17:25 +0100
Subject: [PATCH 1/3] Add PlasmaIgnitionModel enum and refactor plasma ignition
 checks

---
 process/core/solver/constraints.py          | 22 ++++++++++++---------
 process/data_structure/physics_variables.py |  7 +++++++
 process/models/physics/confinement_time.py  |  7 ++++---
 process/models/physics/current_drive.py     |  5 +++--
 process/models/physics/physics.py           |  9 +++++----
 process/models/stellarator/heating.py       |  3 ++-
 process/models/stellarator/stellarator.py   |  5 +++--
 7 files changed, 37 insertions(+), 21 deletions(-)

diff --git a/process/core/solver/constraints.py b/process/core/solver/constraints.py
index 5187004e2d..14eb920146 100644
--- a/process/core/solver/constraints.py
+++ b/process/core/solver/constraints.py
@@ -11,7 +11,11 @@
 from process.data_structure.build_variables import TFCSRadialConfiguration
 from process.models.physics.density_limit import DensityLimitModel
 from process.models.physics.exhaust import PlasmaExhaust
-from process.models.physics.physics import BetaComponentLimits, PlasmaBeta
+from process.models.physics.physics import (
+    BetaComponentLimits,
+    PlasmaBeta,
+    PlasmaIgnitionModel,
+)
 from process.models.tfcoil.base import TFConductorModel
 
 ConstraintSymbolType = Literal["=", ">=", "<="]
@@ -270,14 +274,14 @@ def constraint_equation_2(constraint_registration, data):
         pnumerator = pscaling
 
     # if plasma not ignited include injected power
-    if data.physics.i_plasma_ignited == 0:
+    if data.physics.i_plasma_ignited == PlasmaIgnitionModel.NON_IGNITED:
         pdenom = (
             data.physics.f_p_alpha_plasma_deposited * data.physics.pden_alpha_total_mw
             + data.physics.pden_non_alpha_charged_mw
             + data.physics.pden_plasma_ohmic_mw
             + data.current_drive.p_hcd_injected_total_mw / data.physics.vol_plasma
         )
-    else:
+    elif data.physics.i_plasma_ignited == PlasmaIgnitionModel.IGNITED:
         # if plasma ignited
         pdenom = (
             data.physics.f_p_alpha_plasma_deposited * data.physics.pden_alpha_total_mw
@@ -303,7 +307,7 @@ def constraint_equation_3(constraint_registration, data):
     vol_plasma: plasma volume (m3)
     """
     # No assume plasma ignition:
-    if data.physics.i_plasma_ignited == 0:
+    if data.physics.i_plasma_ignited == PlasmaIgnitionModel.NON_IGNITED:
         return eq(
             (
                 data.physics.pden_ion_transport_loss_mw
@@ -363,14 +367,14 @@ def constraint_equation_4(constraint_registration, data):
         pnumerator = pscaling
 
     # if plasma not ignited include injected power
-    if data.physics.i_plasma_ignited == 0:
+    if data.physics.i_plasma_ignited == PlasmaIgnitionModel.NON_IGNITED:
         pdenom = (
             data.physics.f_p_alpha_plasma_deposited
             * data.physics.f_pden_alpha_electron_mw
             + data.physics.pden_ion_electron_equilibration_mw
             + data.current_drive.p_hcd_injected_electrons_mw / data.physics.vol_plasma
         )
-    else:
+    elif data.physics.i_plasma_ignited == PlasmaIgnitionModel.IGNITED:
         # if plasma ignited
         pdenom = (
             data.physics.f_p_alpha_plasma_deposited
@@ -453,7 +457,7 @@ def constraint_equation_7(constraint_registration, data):
     nd_beam_ions_out: hot beam ion density from calculation (/m³)
     nd_beam_ions: hot beam ion density, variable (/m³)
     """
-    if data.physics.i_plasma_ignited == 1:
+    if data.physics.i_plasma_ignited == PlasmaIgnitionModel.IGNITED:
         raise ProcessValueError("Do not use constraint equation 7 if i_plasma_ignited=1")
 
     return eq(
@@ -1739,12 +1743,12 @@ def constraint_equation_91(constraint_registration, data):
     te0_ecrh_achievable: Max. achievable electron temperature at ignition point
     """
     # Achievable ECRH te needs to be larger than needed te for igntion
-    if data.physics.i_plasma_ignited == 0:
+    if data.physics.i_plasma_ignited == PlasmaIgnitionModel.NON_IGNITED:
         value = (
             data.stellarator.powerht_constraint
             + data.current_drive.p_hcd_primary_extra_heat_mw
         )
-    else:
+    elif data.physics.i_plasma_ignited == PlasmaIgnitionModel.IGNITED:
         value = data.stellarator.powerht_constraint
 
     return geq(
diff --git a/process/data_structure/physics_variables.py b/process/data_structure/physics_variables.py
index 52ee70a627..0cafda166e 100644
--- a/process/data_structure/physics_variables.py
+++ b/process/data_structure/physics_variables.py
@@ -13,6 +13,13 @@
 import numpy as np
 
 
+class PlasmaIgnitionModel(IntEnum):
+    """Enum for plasma ignition models."""
+
+    NON_IGNITED = 0
+    IGNITED = 1
+
+
 class DivertorNumberModels(IntEnum):
     """Enum for divertor number models. `i_single_null` is the index for this enum."""
 
diff --git a/process/models/physics/confinement_time.py b/process/models/physics/confinement_time.py
index 78d6eca7ad..1bca3073e8 100644
--- a/process/models/physics/confinement_time.py
+++ b/process/models/physics/confinement_time.py
@@ -14,6 +14,7 @@
     ConfinementMode,
     ConfinementRadiationLossModel,
     ConfinementTimeModel,
+    PlasmaIgnitionModel,
 )
 from process.models.physics.plasma_geometry import PlasmaGeom
 
@@ -143,7 +144,7 @@ def calculate_confinement_time(
         )
 
         # If the device is not ignited, add the injected auxiliary power
-        if i_plasma_ignited == 0:
+        if i_plasma_ignited == PlasmaIgnitionModel.NON_IGNITED:
             p_plasma_loss_mw += p_hcd_injected_total_mw
 
         # Include the radiation as a loss term based on radiation model
@@ -1101,7 +1102,7 @@ def fhz(hfact: float) -> float:
 
             # Take into account whether injected power is included in tau_e calculation
             # (i.e. whether device is ignited)
-            if self.data.physics.i_plasma_ignited == 0:
+            if self.data.physics.i_plasma_ignited == PlasmaIgnitionModel.NON_IGNITED:
                 fhz_value -= (
                     self.data.current_drive.p_hcd_injected_total_mw
                     / self.data.physics.vol_plasma
@@ -1128,7 +1129,7 @@ def output_confinement_time_info(self):
         """
         po.oheadr(self.outfile, "Plasma Energy Confinement")
 
-        if self.data.physics.i_plasma_ignited == 1:
+        if self.data.physics.i_plasma_ignited == PlasmaIgnitionModel.IGNITED:
             po.ocmmnt(
                 self.outfile,
                 "Device is assumed to be ignited for the calculation of confinement "
diff --git a/process/models/physics/current_drive.py b/process/models/physics/current_drive.py
index 8ff08d57ac..cf66c5619f 100644
--- a/process/models/physics/current_drive.py
+++ b/process/models/physics/current_drive.py
@@ -12,6 +12,7 @@
 )
 from process.core.exceptions import ProcessError, ProcessValueError
 from process.core.model import Model
+from process.data_structure.physics_variables import PlasmaIgnitionModel
 from process.models.physics.plasma_profiles import PlasmaProfile
 
 logger = logging.getLogger(__name__)
@@ -2290,7 +2291,7 @@ def current_drive(self):
             )
 
             # Reset injected power to zero for ignited plasma (fudge)
-            if self.data.physics.i_plasma_ignited == 1:
+            if self.data.physics.i_plasma_ignited == PlasmaIgnitionModel.IGNITED:
                 self.data.heat_transport.p_hcd_electric_total_mw = 0.0e0
 
             # Ratio of fusion to input (injection+ohmic) power
@@ -2394,7 +2395,7 @@ def output(self):
             "(i_plasma_ignited)",
             self.data.physics.i_plasma_ignited,
         )
-        if self.data.physics.i_plasma_ignited == 1:
+        if self.data.physics.i_plasma_ignited == PlasmaIgnitionModel.IGNITED:
             po.ocmmnt(
                 self.outfile,
                 "Ignited plasma; injected power only used for start-up phase",
diff --git a/process/models/physics/physics.py b/process/models/physics/physics.py
index 17e9a0bec7..d5739d8049 100644
--- a/process/models/physics/physics.py
+++ b/process/models/physics/physics.py
@@ -18,6 +18,7 @@
 from process.core.exceptions import ProcessValueError
 from process.core.model import Model
 from process.data_structure.impurity_radiation_variables import N_IMPURITIES
+from process.data_structure.physics_variables import PlasmaIgnitionModel
 from process.models.physics import impurity_radiation
 from process.models.physics.profiles import (
     DensityProfilePedestalType,
@@ -601,7 +602,7 @@ def run(self):
         # Calculate neutral beam slowing down effects
         # If ignited, then ignore beam fusion effects
         if (self.data.current_drive.c_beam_total != 0.0e0) and (  # noqa: RUF069
-            self.data.physics.i_plasma_ignited == 0
+            self.data.physics.i_plasma_ignited == PlasmaIgnitionModel.NON_IGNITED
         ):
             (
                 self.data.physics.beta_beam,
@@ -773,7 +774,7 @@ def run(self):
         # which is assumed to be absorbed by the first wall
         pinj = (
             self.data.current_drive.p_hcd_injected_total_mw
-            if self.data.physics.i_plasma_ignited == 0
+            if self.data.physics.i_plasma_ignited == PlasmaIgnitionModel.NON_IGNITED
             else 0.0
         )
 
@@ -1176,7 +1177,7 @@ def plasma_composition(self):
 
         # Beam hot ion component
         # If ignited, prevent beam fusion effects
-        if self.data.physics.i_plasma_ignited == 0:
+        if self.data.physics.i_plasma_ignited == PlasmaIgnitionModel.NON_IGNITED:
             self.data.physics.nd_beam_ions = (
                 self.data.physics.nd_plasma_electrons_vol_avg
                 * self.data.physics.f_nd_beam_electron
@@ -2295,7 +2296,7 @@ def outplas(self):
             self.data.current_drive.p_hcd_injected_electrons_mw,
             "OP ",
         )
-        if self.data.physics.i_plasma_ignited == 1:
+        if self.data.physics.i_plasma_ignited == PlasmaIgnitionModel.IGNITED:
             po.ocmmnt(self.outfile, "  (Injected power only used for start-up phase)")
 
         self.exhaust.output()
diff --git a/process/models/stellarator/heating.py b/process/models/stellarator/heating.py
index 302c63fd6f..349c1bd1f7 100644
--- a/process/models/stellarator/heating.py
+++ b/process/models/stellarator/heating.py
@@ -3,6 +3,7 @@
 from process.core import process_output as po
 from process.core.exceptions import ProcessValueError
 from process.core.model import DataStructure
+from process.data_structure.physics_variables import PlasmaIgnitionModel
 
 logger = logging.getLogger(__name__)
 
@@ -142,7 +143,7 @@ def output(stellarator, data: DataStructure, f_p_beam_injected_ions=None):
     elif data.stellarator.isthtr == 3:
         po.ocmmnt(stellarator.outfile, "Neutral Beam Injection Heating")
 
-    if data.physics.i_plasma_ignited == 1:
+    if data.physics.i_plasma_ignited == PlasmaIgnitionModel.IGNITED:
         po.ocmmnt(
             stellarator.outfile,
             "Ignited plasma; injected power only used for start-up phase",
diff --git a/process/models/stellarator/stellarator.py b/process/models/stellarator/stellarator.py
index 0a0b17b309..4a1cba88ae 100644
--- a/process/models/stellarator/stellarator.py
+++ b/process/models/stellarator/stellarator.py
@@ -13,6 +13,7 @@
 from process.core.coolprop_interface import FluidProperties
 from process.core.exceptions import ProcessValueError
 from process.core.model import Model
+from process.data_structure.physics_variables import PlasmaIgnitionModel
 from process.models.engineering.pumping import CoolantType
 from process.models.physics.physics import Physics, rether
 from process.models.power import PumpingPowerModelTypes
@@ -1975,7 +1976,7 @@ def st_phys(self, output):
         #  If ignited, then ignore beam fusion effects
 
         if (self.data.current_drive.p_hcd_beam_injected_total_mw != 0.0e0) and (  # noqa: RUF069
-            self.data.physics.i_plasma_ignited == 0
+            self.data.physics.i_plasma_ignited == PlasmaIgnitionModel.NON_IGNITED
         ):
             (
                 self.data.physics.beta_beam,
@@ -2152,7 +2153,7 @@ def st_phys(self, output):
             0.00001e0, powht
         )  # To avoid negative heating power. This line is VERY important
 
-        if self.data.physics.i_plasma_ignited == 0:
+        if self.data.physics.i_plasma_ignited == PlasmaIgnitionModel.NON_IGNITED:
             # if not ignited add the auxiliary power
             powht += self.data.current_drive.p_hcd_injected_total_mw
 

From c0f88a46ff631306cb9733fd5d228010fc1453db Mon Sep 17 00:00:00 2001
From: mn3981 <christopher.ashe@ukaea.uk>
Date: Thu, 9 Jul 2026 09:19:30 +0100
Subject: [PATCH 2/3] Refactor plasma ignition parameter to use
 PlasmaIgnitionModel enum

---
 tests/unit/models/physics/test_physics.py | 37 ++++++++++++-----------
 1 file changed, 19 insertions(+), 18 deletions(-)

diff --git a/tests/unit/models/physics/test_physics.py b/tests/unit/models/physics/test_physics.py
index 9d9351e200..63613de811 100644
--- a/tests/unit/models/physics/test_physics.py
+++ b/tests/unit/models/physics/test_physics.py
@@ -6,6 +6,7 @@
 import pytest
 
 from process.core import constants
+from process.data_structure.physics_variables import PlasmaIgnitionModel
 from process.models.physics.impurity_radiation import initialise_imprad
 from process.models.physics.physics import (
     DetailedPhysics,
@@ -1373,7 +1374,7 @@ class PlasmaCompositionParam(NamedTuple):
                 183.84999999999999,
             ]),
             alphat=1.45,
-            i_plasma_ignited=0,
+            i_plasma_ignited=PlasmaIgnitionModel.NON_IGNITED,
             f_alpha_electron=0,
             m_fuel_amu=0,
             f_plasma_fuel_tritium=0.5,
@@ -1479,7 +1480,7 @@ class PlasmaCompositionParam(NamedTuple):
                 order="F",
             ).transpose(),
             alphat=1.45,
-            i_plasma_ignited=0,
+            i_plasma_ignited=PlasmaIgnitionModel.NON_IGNITED,
             f_alpha_electron=0.6845930883190634,
             m_fuel_amu=2.5,
             f_plasma_fuel_tritium=0.5,
@@ -2268,7 +2269,7 @@ class ConfinementTimeParam(NamedTuple):
             p_plasma_ohmic_mw=0.63634001890069991,
             f_p_alpha_plasma_deposited=0.94999999999999996,
             i_confinement_time=32,
-            i_plasma_ignited=0,
+            i_plasma_ignited=PlasmaIgnitionModel.NON_IGNITED,
             m_fuel_amu=2.5,
             p_alpha_total_mw=319.03020327154269,
             aspect=3,
@@ -2320,7 +2321,7 @@ class ConfinementTimeParam(NamedTuple):
             p_plasma_ohmic_mw=0.63634001890069991,
             f_p_alpha_plasma_deposited=0.94999999999999996,
             i_confinement_time=33,
-            i_plasma_ignited=0,
+            i_plasma_ignited=PlasmaIgnitionModel.NON_IGNITED,
             m_fuel_amu=2.5,
             p_alpha_total_mw=319.03020327154269,
             aspect=3,
@@ -2372,7 +2373,7 @@ class ConfinementTimeParam(NamedTuple):
             p_plasma_ohmic_mw=0.63634001890069991,
             f_p_alpha_plasma_deposited=0.94999999999999996,
             i_confinement_time=34,
-            i_plasma_ignited=0,
+            i_plasma_ignited=PlasmaIgnitionModel.NON_IGNITED,
             m_fuel_amu=2.5,
             p_alpha_total_mw=319.03020327154269,
             aspect=3,
@@ -2424,7 +2425,7 @@ class ConfinementTimeParam(NamedTuple):
             p_plasma_ohmic_mw=0.63634001890069991,
             f_p_alpha_plasma_deposited=0.94999999999999996,
             i_confinement_time=35,
-            i_plasma_ignited=0,
+            i_plasma_ignited=PlasmaIgnitionModel.NON_IGNITED,
             m_fuel_amu=2.5,
             p_alpha_total_mw=319.03020327154269,
             aspect=3,
@@ -2476,7 +2477,7 @@ class ConfinementTimeParam(NamedTuple):
             p_plasma_ohmic_mw=0.63634001890069991,
             f_p_alpha_plasma_deposited=0.94999999999999996,
             i_confinement_time=36,
-            i_plasma_ignited=0,
+            i_plasma_ignited=PlasmaIgnitionModel.NON_IGNITED,
             m_fuel_amu=2.5,
             p_alpha_total_mw=319.03020327154269,
             aspect=3,
@@ -2528,7 +2529,7 @@ class ConfinementTimeParam(NamedTuple):
             p_plasma_ohmic_mw=0.63634001890069991,
             f_p_alpha_plasma_deposited=0.94999999999999996,
             i_confinement_time=37,
-            i_plasma_ignited=0,
+            i_plasma_ignited=PlasmaIgnitionModel.NON_IGNITED,
             m_fuel_amu=2.5,
             p_alpha_total_mw=319.03020327154269,
             aspect=3,
@@ -2580,7 +2581,7 @@ class ConfinementTimeParam(NamedTuple):
             p_plasma_ohmic_mw=0.63634001890069991,
             f_p_alpha_plasma_deposited=0.94999999999999996,
             i_confinement_time=38,
-            i_plasma_ignited=0,
+            i_plasma_ignited=PlasmaIgnitionModel.NON_IGNITED,
             m_fuel_amu=2.5,
             p_alpha_total_mw=319.03020327154269,
             aspect=3,
@@ -2632,7 +2633,7 @@ class ConfinementTimeParam(NamedTuple):
             p_plasma_ohmic_mw=0.63634001890069991,
             f_p_alpha_plasma_deposited=0.94999999999999996,
             i_confinement_time=39,
-            i_plasma_ignited=0,
+            i_plasma_ignited=PlasmaIgnitionModel.NON_IGNITED,
             m_fuel_amu=2.5,
             p_alpha_total_mw=319.03020327154269,
             aspect=3,
@@ -2684,7 +2685,7 @@ class ConfinementTimeParam(NamedTuple):
             p_plasma_ohmic_mw=0.63634001890069991,
             f_p_alpha_plasma_deposited=0.94999999999999996,
             i_confinement_time=40,
-            i_plasma_ignited=0,
+            i_plasma_ignited=PlasmaIgnitionModel.NON_IGNITED,
             m_fuel_amu=2.5,
             p_alpha_total_mw=319.03020327154269,
             aspect=3,
@@ -2736,7 +2737,7 @@ class ConfinementTimeParam(NamedTuple):
             p_plasma_ohmic_mw=0.63634001890069991,
             f_p_alpha_plasma_deposited=0.94999999999999996,
             i_confinement_time=41,
-            i_plasma_ignited=0,
+            i_plasma_ignited=PlasmaIgnitionModel.NON_IGNITED,
             m_fuel_amu=2.5,
             p_alpha_total_mw=319.03020327154269,
             aspect=3,
@@ -2788,7 +2789,7 @@ class ConfinementTimeParam(NamedTuple):
             p_plasma_ohmic_mw=0.63634001890069991,
             f_p_alpha_plasma_deposited=0.94999999999999996,
             i_confinement_time=42,
-            i_plasma_ignited=0,
+            i_plasma_ignited=PlasmaIgnitionModel.NON_IGNITED,
             m_fuel_amu=2.5,
             p_alpha_total_mw=319.03020327154269,
             aspect=3,
@@ -2840,7 +2841,7 @@ class ConfinementTimeParam(NamedTuple):
             p_plasma_ohmic_mw=0.63634001890069991,
             f_p_alpha_plasma_deposited=0.94999999999999996,
             i_confinement_time=43,
-            i_plasma_ignited=0,
+            i_plasma_ignited=PlasmaIgnitionModel.NON_IGNITED,
             m_fuel_amu=2.5,
             p_alpha_total_mw=319.03020327154269,
             aspect=3,
@@ -2892,7 +2893,7 @@ class ConfinementTimeParam(NamedTuple):
             p_plasma_ohmic_mw=0.63634001890069991,
             f_p_alpha_plasma_deposited=0.94999999999999996,
             i_confinement_time=44,
-            i_plasma_ignited=0,
+            i_plasma_ignited=PlasmaIgnitionModel.NON_IGNITED,
             m_fuel_amu=2.5,
             p_alpha_total_mw=319.03020327154269,
             aspect=3,
@@ -2944,7 +2945,7 @@ class ConfinementTimeParam(NamedTuple):
             p_plasma_ohmic_mw=0.63634001890069991,
             f_p_alpha_plasma_deposited=0.94999999999999996,
             i_confinement_time=45,
-            i_plasma_ignited=0,
+            i_plasma_ignited=PlasmaIgnitionModel.NON_IGNITED,
             m_fuel_amu=2.5,
             p_alpha_total_mw=319.03020327154269,
             aspect=3,
@@ -2996,7 +2997,7 @@ class ConfinementTimeParam(NamedTuple):
             p_plasma_ohmic_mw=0.63634001890069991,
             f_p_alpha_plasma_deposited=0.94999999999999996,
             i_confinement_time=46,
-            i_plasma_ignited=0,
+            i_plasma_ignited=PlasmaIgnitionModel.NON_IGNITED,
             m_fuel_amu=2.5,
             p_alpha_total_mw=319.03020327154269,
             aspect=3,
@@ -3048,7 +3049,7 @@ class ConfinementTimeParam(NamedTuple):
             p_plasma_ohmic_mw=0.63634001890069991,
             f_p_alpha_plasma_deposited=0.94999999999999996,
             i_confinement_time=47,
-            i_plasma_ignited=0,
+            i_plasma_ignited=PlasmaIgnitionModel.NON_IGNITED,
             m_fuel_amu=2.5,
             p_alpha_total_mw=319.03020327154269,
             aspect=3,

From eb3540f48a43745269aae26f66dfcd8ffc14b69c Mon Sep 17 00:00:00 2001
From: mn3981 <christopher.ashe@ukaea.uk>
Date: Thu, 9 Jul 2026 13:18:47 +0100
Subject: [PATCH 3/3] Refactor plasma ignition checks to use
 PlasmaIgnitionModel enum for consistency

---
 process/core/solver/constraints.py         | 33 ++++++++++++++++------
 process/models/physics/confinement_time.py | 12 ++++++--
 process/models/physics/current_drive.py    | 10 +++++--
 process/models/physics/physics.py          | 16 ++++++++---
 process/models/stellarator/heating.py      |  2 +-
 process/models/stellarator/stellarator.py  |  8 ++++--
 6 files changed, 60 insertions(+), 21 deletions(-)

diff --git a/process/core/solver/constraints.py b/process/core/solver/constraints.py
index 14eb920146..c1d104e89b 100644
--- a/process/core/solver/constraints.py
+++ b/process/core/solver/constraints.py
@@ -274,14 +274,17 @@ def constraint_equation_2(constraint_registration, data):
         pnumerator = pscaling
 
     # if plasma not ignited include injected power
-    if data.physics.i_plasma_ignited == PlasmaIgnitionModel.NON_IGNITED:
+    if (
+        PlasmaIgnitionModel(data.physics.i_plasma_ignited)
+        == PlasmaIgnitionModel.NON_IGNITED
+    ):
         pdenom = (
             data.physics.f_p_alpha_plasma_deposited * data.physics.pden_alpha_total_mw
             + data.physics.pden_non_alpha_charged_mw
             + data.physics.pden_plasma_ohmic_mw
             + data.current_drive.p_hcd_injected_total_mw / data.physics.vol_plasma
         )
-    elif data.physics.i_plasma_ignited == PlasmaIgnitionModel.IGNITED:
+    else:
         # if plasma ignited
         pdenom = (
             data.physics.f_p_alpha_plasma_deposited * data.physics.pden_alpha_total_mw
@@ -307,7 +310,10 @@ def constraint_equation_3(constraint_registration, data):
     vol_plasma: plasma volume (m3)
     """
     # No assume plasma ignition:
-    if data.physics.i_plasma_ignited == PlasmaIgnitionModel.NON_IGNITED:
+    if (
+        PlasmaIgnitionModel(data.physics.i_plasma_ignited)
+        == PlasmaIgnitionModel.NON_IGNITED
+    ):
         return eq(
             (
                 data.physics.pden_ion_transport_loss_mw
@@ -367,14 +373,17 @@ def constraint_equation_4(constraint_registration, data):
         pnumerator = pscaling
 
     # if plasma not ignited include injected power
-    if data.physics.i_plasma_ignited == PlasmaIgnitionModel.NON_IGNITED:
+    if (
+        PlasmaIgnitionModel(data.physics.i_plasma_ignited)
+        == PlasmaIgnitionModel.NON_IGNITED
+    ):
         pdenom = (
             data.physics.f_p_alpha_plasma_deposited
             * data.physics.f_pden_alpha_electron_mw
             + data.physics.pden_ion_electron_equilibration_mw
             + data.current_drive.p_hcd_injected_electrons_mw / data.physics.vol_plasma
         )
-    elif data.physics.i_plasma_ignited == PlasmaIgnitionModel.IGNITED:
+    else:
         # if plasma ignited
         pdenom = (
             data.physics.f_p_alpha_plasma_deposited
@@ -457,7 +466,7 @@ def constraint_equation_7(constraint_registration, data):
     nd_beam_ions_out: hot beam ion density from calculation (/m³)
     nd_beam_ions: hot beam ion density, variable (/m³)
     """
-    if data.physics.i_plasma_ignited == PlasmaIgnitionModel.IGNITED:
+    if PlasmaIgnitionModel(data.physics.i_plasma_ignited) == PlasmaIgnitionModel.IGNITED:
         raise ProcessValueError("Do not use constraint equation 7 if i_plasma_ignited=1")
 
     return eq(
@@ -812,7 +821,10 @@ def constraint_equation_28(constraint_registration, data):
     during plasma start-up, and is excluded from all steady-state
     power balance calculations.
     """
-    if data.physics.i_plasma_ignited != 0:
+    if (
+        PlasmaIgnitionModel(data.physics.i_plasma_ignited)
+        != PlasmaIgnitionModel.NON_IGNITED
+    ):
         raise ProcessValueError("Do not use constraint 28 if i_plasma_ignited=1")
 
     return geq(
@@ -1743,12 +1755,15 @@ def constraint_equation_91(constraint_registration, data):
     te0_ecrh_achievable: Max. achievable electron temperature at ignition point
     """
     # Achievable ECRH te needs to be larger than needed te for igntion
-    if data.physics.i_plasma_ignited == PlasmaIgnitionModel.NON_IGNITED:
+    if (
+        PlasmaIgnitionModel(data.physics.i_plasma_ignited)
+        == PlasmaIgnitionModel.NON_IGNITED
+    ):
         value = (
             data.stellarator.powerht_constraint
             + data.current_drive.p_hcd_primary_extra_heat_mw
         )
-    elif data.physics.i_plasma_ignited == PlasmaIgnitionModel.IGNITED:
+    else:
         value = data.stellarator.powerht_constraint
 
     return geq(
diff --git a/process/models/physics/confinement_time.py b/process/models/physics/confinement_time.py
index 1bca3073e8..87bd9ff4ad 100644
--- a/process/models/physics/confinement_time.py
+++ b/process/models/physics/confinement_time.py
@@ -144,7 +144,7 @@ def calculate_confinement_time(
         )
 
         # If the device is not ignited, add the injected auxiliary power
-        if i_plasma_ignited == PlasmaIgnitionModel.NON_IGNITED:
+        if PlasmaIgnitionModel(i_plasma_ignited) == PlasmaIgnitionModel.NON_IGNITED:
             p_plasma_loss_mw += p_hcd_injected_total_mw
 
         # Include the radiation as a loss term based on radiation model
@@ -1102,7 +1102,10 @@ def fhz(hfact: float) -> float:
 
             # Take into account whether injected power is included in tau_e calculation
             # (i.e. whether device is ignited)
-            if self.data.physics.i_plasma_ignited == PlasmaIgnitionModel.NON_IGNITED:
+            if (
+                PlasmaIgnitionModel(self.data.physics.i_plasma_ignited)
+                == PlasmaIgnitionModel.NON_IGNITED
+            ):
                 fhz_value -= (
                     self.data.current_drive.p_hcd_injected_total_mw
                     / self.data.physics.vol_plasma
@@ -1129,7 +1132,10 @@ def output_confinement_time_info(self):
         """
         po.oheadr(self.outfile, "Plasma Energy Confinement")
 
-        if self.data.physics.i_plasma_ignited == PlasmaIgnitionModel.IGNITED:
+        if (
+            PlasmaIgnitionModel(self.data.physics.i_plasma_ignited)
+            == PlasmaIgnitionModel.IGNITED
+        ):
             po.ocmmnt(
                 self.outfile,
                 "Device is assumed to be ignited for the calculation of confinement "
diff --git a/process/models/physics/current_drive.py b/process/models/physics/current_drive.py
index cf66c5619f..9d63db895a 100644
--- a/process/models/physics/current_drive.py
+++ b/process/models/physics/current_drive.py
@@ -2291,7 +2291,10 @@ def current_drive(self):
             )
 
             # Reset injected power to zero for ignited plasma (fudge)
-            if self.data.physics.i_plasma_ignited == PlasmaIgnitionModel.IGNITED:
+            if (
+                PlasmaIgnitionModel(self.data.physics.i_plasma_ignited)
+                == PlasmaIgnitionModel.IGNITED
+            ):
                 self.data.heat_transport.p_hcd_electric_total_mw = 0.0e0
 
             # Ratio of fusion to input (injection+ohmic) power
@@ -2395,7 +2398,10 @@ def output(self):
             "(i_plasma_ignited)",
             self.data.physics.i_plasma_ignited,
         )
-        if self.data.physics.i_plasma_ignited == PlasmaIgnitionModel.IGNITED:
+        if (
+            PlasmaIgnitionModel(self.data.physics.i_plasma_ignited)
+            == PlasmaIgnitionModel.IGNITED
+        ):
             po.ocmmnt(
                 self.outfile,
                 "Ignited plasma; injected power only used for start-up phase",
diff --git a/process/models/physics/physics.py b/process/models/physics/physics.py
index d5739d8049..e3fd405c3d 100644
--- a/process/models/physics/physics.py
+++ b/process/models/physics/physics.py
@@ -602,7 +602,8 @@ def run(self):
         # Calculate neutral beam slowing down effects
         # If ignited, then ignore beam fusion effects
         if (self.data.current_drive.c_beam_total != 0.0e0) and (  # noqa: RUF069
-            self.data.physics.i_plasma_ignited == PlasmaIgnitionModel.NON_IGNITED
+            PlasmaIgnitionModel(self.data.physics.i_plasma_ignited)
+            == PlasmaIgnitionModel.NON_IGNITED
         ):
             (
                 self.data.physics.beta_beam,
@@ -774,7 +775,8 @@ def run(self):
         # which is assumed to be absorbed by the first wall
         pinj = (
             self.data.current_drive.p_hcd_injected_total_mw
-            if self.data.physics.i_plasma_ignited == PlasmaIgnitionModel.NON_IGNITED
+            if PlasmaIgnitionModel(self.data.physics.i_plasma_ignited)
+            == PlasmaIgnitionModel.NON_IGNITED
             else 0.0
         )
 
@@ -1177,7 +1179,10 @@ def plasma_composition(self):
 
         # Beam hot ion component
         # If ignited, prevent beam fusion effects
-        if self.data.physics.i_plasma_ignited == PlasmaIgnitionModel.NON_IGNITED:
+        if (
+            PlasmaIgnitionModel(self.data.physics.i_plasma_ignited)
+            == PlasmaIgnitionModel.NON_IGNITED
+        ):
             self.data.physics.nd_beam_ions = (
                 self.data.physics.nd_plasma_electrons_vol_avg
                 * self.data.physics.f_nd_beam_electron
@@ -2296,7 +2301,10 @@ def outplas(self):
             self.data.current_drive.p_hcd_injected_electrons_mw,
             "OP ",
         )
-        if self.data.physics.i_plasma_ignited == PlasmaIgnitionModel.IGNITED:
+        if (
+            PlasmaIgnitionModel(self.data.physics.i_plasma_ignited)
+            == PlasmaIgnitionModel.IGNITED
+        ):
             po.ocmmnt(self.outfile, "  (Injected power only used for start-up phase)")
 
         self.exhaust.output()
diff --git a/process/models/stellarator/heating.py b/process/models/stellarator/heating.py
index 349c1bd1f7..fd4bd43aab 100644
--- a/process/models/stellarator/heating.py
+++ b/process/models/stellarator/heating.py
@@ -143,7 +143,7 @@ def output(stellarator, data: DataStructure, f_p_beam_injected_ions=None):
     elif data.stellarator.isthtr == 3:
         po.ocmmnt(stellarator.outfile, "Neutral Beam Injection Heating")
 
-    if data.physics.i_plasma_ignited == PlasmaIgnitionModel.IGNITED:
+    if PlasmaIgnitionModel(data.physics.i_plasma_ignited) == PlasmaIgnitionModel.IGNITED:
         po.ocmmnt(
             stellarator.outfile,
             "Ignited plasma; injected power only used for start-up phase",
diff --git a/process/models/stellarator/stellarator.py b/process/models/stellarator/stellarator.py
index 4a1cba88ae..e1ca8c8685 100644
--- a/process/models/stellarator/stellarator.py
+++ b/process/models/stellarator/stellarator.py
@@ -1976,7 +1976,8 @@ def st_phys(self, output):
         #  If ignited, then ignore beam fusion effects
 
         if (self.data.current_drive.p_hcd_beam_injected_total_mw != 0.0e0) and (  # noqa: RUF069
-            self.data.physics.i_plasma_ignited == PlasmaIgnitionModel.NON_IGNITED
+            PlasmaIgnitionModel(self.data.physics.i_plasma_ignited)
+            == PlasmaIgnitionModel.NON_IGNITED
         ):
             (
                 self.data.physics.beta_beam,
@@ -2153,7 +2154,10 @@ def st_phys(self, output):
             0.00001e0, powht
         )  # To avoid negative heating power. This line is VERY important
 
-        if self.data.physics.i_plasma_ignited == PlasmaIgnitionModel.NON_IGNITED:
+        if (
+            PlasmaIgnitionModel(self.data.physics.i_plasma_ignited)
+            == PlasmaIgnitionModel.NON_IGNITED
+        ):
             # if not ignited add the auxiliary power
             powht += self.data.current_drive.p_hcd_injected_total_mw