❇️ ♻️ Create Beta class #4053

chris-ashe · 2026-01-20T14:39:32Z

This pull request introduces a new PlasmaBeta class to centralize and standardize plasma beta calculations across the codebase. The changes refactor existing code to use this class, update dependencies, and add new unit tests for its methods. The most important changes are grouped below:

Core Refactoring and Architecture:

Added a new PlasmaBeta class to process.physics and refactored the codebase to use this class for all plasma beta-related calculations, replacing previous standalone functions.
Updated the initialization of major classes (main.py, stellarator.py) to instantiate and pass PlasmaBeta objects where needed, ensuring consistent access to beta calculations throughout the application.
Code Cleanup and Removal:
Removed the now-obsolete fast_alpha_beta function from process/physics_functions.py, migrating its logic to the new PlasmaBeta class.
Updated all usages of beta calculation functions to use the new class methods, including replacing calls in the Stellarator model.

Testing and Validation:

Refactored unit tests in test_physics.py and test_stellarator.py to use the new PlasmaBeta class and its methods, ensuring all previous tests remain valid and comprehensive.
Added new unit tests for additional PlasmaBeta methods, such as calculate_normalised_beta and calculate_plasma_energy_from_beta, to improve coverage and reliability.

Dependency and Import Updates:

Cleaned up imports in affected files to remove unused beta calculation functions and ensure all references point to the new PlasmaBeta class.

These changes improve maintainability by centralizing plasma beta logic, reduce code duplication, and enhance test coverage.## Description

Checklist

I confirm that I have completed the following checks:

My changes follow the PROCESS style guide
I have justified any large differences in the regression tests caused by this pull request in the comments.
I have added new tests where appropriate for the changes I have made.
If I have had to change any existing unit or integration tests, I have justified this change in the pull request comments.
If I have made documentation changes, I have checked they render correctly.
I have added documentation for my change, if appropriate.

codecov-commenter · 2026-01-20T15:12:15Z

Codecov Report

❌ Patch coverage is 37.24138% with 91 lines in your changes missing coverage. Please review.
✅ Project coverage is 46.49%. Comparing base (6ba13ca) to head (a68cdac).
⚠️ Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
process/physics.py	36.61%	90 Missing ⚠️
process/main.py	50.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4053      +/-   ##
==========================================
+ Coverage   46.47%   46.49%   +0.02%     
==========================================
  Files         123      124       +1     
  Lines       28902    28955      +53     
==========================================
+ Hits        13432    13464      +32     
- Misses      15470    15491      +21

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process/physics.py

…anization

…roved clarity and maintainability

… redundant function from physics_functions.py

…ndant function from physics.py

…d remove redundant function

…ss method

…or improved maintainability

…d and improve error handling

…esson, Original Scaling, Menard, Tholerus, and Stambaugh relations

…variable formatting

…roved organization and maintainability

timothy-nunn

I still think some more calculations can be moved into the new class

timothy-nunn · 2026-02-11T09:59:15Z

process/physics.py

+        # Normalised beta from Troyon beta limit
+        physics_variables.beta_norm_total = self.beta.calculate_normalised_beta(
+            beta=physics_variables.beta_total_vol_avg,
+            rminor=physics_variables.rminor,
+            c_plasma=physics_variables.plasma_current,
+            b_field=physics_variables.b_plasma_toroidal_on_axis,
+        )


I think this can go into the Beta.run section

process/physics.py

timothy-nunn · 2026-02-11T10:01:50Z

process/physics.py

+        physics_variables.beta_norm_max_wesson = (
+            self.beta.calculate_beta_norm_max_wesson(
+                ind_plasma_internal_norm=physics_variables.ind_plasma_internal_norm
+            )


And this calculation

timothy-nunn · 2026-02-11T10:02:01Z

process/physics.py

        # Original scaling law
        physics_variables.beta_norm_max_original_scaling = (
-            self.calculate_beta_norm_max_original(eps=physics_variables.eps)
+            self.beta.calculate_beta_norm_max_original(eps=physics_variables.eps)


And this one

timothy-nunn · 2026-02-11T10:02:10Z

process/physics.py

-        physics_variables.beta_norm_max_menard = self.calculate_beta_norm_max_menard(
-            eps=physics_variables.eps
+        physics_variables.beta_norm_max_menard = (
+            self.beta.calculate_beta_norm_max_menard(eps=physics_variables.eps)


And this one

timothy-nunn · 2026-02-11T10:02:19Z

process/physics.py

+        physics_variables.beta_norm_max_thloreus = (
+            self.beta.calculate_beta_norm_max_thloreus(
+                c_beta=physics_variables.c_beta,
+                pres_plasma_on_axis=physics_variables.pres_plasma_thermal_on_axis,
+                pres_plasma_vol_avg=physics_variables.pres_plasma_thermal_vol_avg,
+            )


And this one

timothy-nunn · 2026-02-11T10:02:30Z

process/physics.py

        physics_variables.beta_norm_max_stambaugh = (
-            self.calculate_beta_norm_max_stambaugh(
+            self.beta.calculate_beta_norm_max_stambaugh(
                f_c_plasma_bootstrap=current_drive_variables.f_c_plasma_bootstrap,
                kappa=physics_variables.kappa,


And this one

timothy-nunn · 2026-02-11T10:03:20Z

process/physics.py

+        try:
+            model = BetaNormMaxModel(int(physics_variables.i_beta_norm_max))
+            physics_variables.beta_norm_max = self.beta.get_beta_norm_max_value(model)
+        except ValueError:
            raise ProcessValueError(
                "Illegal value of i_beta_norm_max",
                i_beta_norm_max=physics_variables.i_beta_norm_max,
-            )
+            ) from None

        # calculate_beta_limit() returns the beta_vol_avg_max for beta
-        physics_variables.beta_vol_avg_max = calculate_beta_limit(
-            physics_variables.b_plasma_toroidal_on_axis,
-            physics_variables.beta_norm_max,
-            physics_variables.plasma_current,
-            physics_variables.rminor,
+        physics_variables.beta_vol_avg_max = self.beta.calculate_beta_limit_from_norm(
+            b_plasma_toroidal_on_axis=physics_variables.b_plasma_toroidal_on_axis,
+            beta_norm_max=physics_variables.beta_norm_max,
+            plasma_current=physics_variables.plasma_current,
+            rminor=physics_variables.rminor,


And this bit?

…ved organization and maintainability

chris-ashe self-assigned this Jan 20, 2026

chris-ashe added Physics Relating to the physics models Refactor labels Jan 20, 2026

chris-ashe force-pushed the create_beta_class branch 2 times, most recently from 20e44af to ce7c700 Compare January 20, 2026 15:02

chris-ashe force-pushed the create_beta_class branch 5 times, most recently from 00a9ee6 to ec47444 Compare January 21, 2026 09:08

chris-ashe requested a review from timothy-nunn January 21, 2026 10:11

chris-ashe marked this pull request as ready for review January 21, 2026 10:11

timothy-nunn reviewed Jan 21, 2026

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timothy-nunn assigned timothy-nunn and unassigned chris-ashe Jan 21, 2026

chris-ashe requested a review from a team as a code owner January 28, 2026 10:01

chris-ashe requested a review from timothy-nunn February 4, 2026 11:22

chris-ashe force-pushed the create_beta_class branch from bdebe55 to c75741c Compare February 4, 2026 11:31

chris-ashe added 11 commits February 10, 2026 13:06

Add PlasmaBeta class and integrate into Physics initialization

da3ed66

Refactor beta normalization calculations to use PlasmaBeta class methods

3a29f60

Add static method to PlasmaBeta for calculating normalized beta

b212a5a

Refactor beta information output to PlasmaBeta class for improved org…

f602e6c

…anization

Move total normalised beta calc to outside of calculate_plasma_current

6564be6

Add static method to PlasmaBeta for calculating plasma energy from beta

b7961a7

Refactor plasma energy calculations to use PlasmaBeta methods for imp…

6c6b998

…roved clarity and maintainability

Refactor fast alpha beta calculation into PlasmaBeta class and remove…

f61ff69

… redundant function from physics_functions.py

Refactor beta limit calculation into PlasmaBeta class and remove redu…

2de1851

…ndant function from physics.py

Refactor poloidal beta calculation to use PlasmaBeta class methods an…

3d09829

…d remove redundant function

Refactor thermal beta normalization calculation to use PlasmaBeta cla…

24637b7

…ss method

chris-ashe added 5 commits February 10, 2026 13:06

Refactor beta norm max calculation to use PlasmaBeta class property f…

550362c

…or improved maintainability

Refactor beta norm max calculation to use BetaNormMaxModel Enum metho…

308380e

…d and improve error handling

Update plasma beta documentation to include function references for W…

3204a7f

…esson, Original Scaling, Menard, Tholerus, and Stambaugh relations

Refactor plasma current documentation for clarity and consistency in …

5a26b40

…variable formatting

Refactor plasma beta calculations into a dedicated run method for imp…

6e872d5

…roved organization and maintainability

chris-ashe force-pushed the create_beta_class branch from c75741c to 6e872d5 Compare February 10, 2026 13:06

timothy-nunn reviewed Feb 11, 2026

View reviewed changes

chris-ashe force-pushed the create_beta_class branch from 3005857 to 6e872d5 Compare February 11, 2026 13:32

Refactor normalized beta calculations into PlasmaBeta class for impro…

a68cdac

…ved organization and maintainability

timothy-nunn approved these changes Feb 11, 2026

View reviewed changes

timothy-nunn merged commit e827793 into main Feb 11, 2026
10 checks passed

timothy-nunn deleted the create_beta_class branch February 11, 2026 14:51

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❇️ ♻️ Create Beta class #4053

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