Add DivertorNumberModels enum and refactor i_single_null usage across…

[chris-ashe]

… models

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.

[Copilot]

Pull request overview

This PR introduces a DivertorNumberModels IntEnum intended to replace the raw i_single_null magic numbers (0/1) and refactors several model call sites to compare against the enum values for improved readability/consistency.

Changes:

• Add DivertorNumberModels enum (intended mapping: DOUBLE_NULL=0, SINGLE_NULL=1).
• Refactor i_single_null comparisons in TF coil shaping, plasma geometry, divertor heat-load sizing, and build/init validation logic.
• Start casting physics_variables.i_single_null to the enum in parts of process/models/build.py and process/core/init.py.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
process/models/build.py	Adds DivertorNumberModels and uses it in vertical/radial build logic.
process/models/tfcoil/base.py	Uses the enum in TF coil inner shape logic and adds an import for it.
process/models/geometry/plasma.py	Uses the enum in plasma boundary generation for single vs double null.
process/models/divertor.py	Uses the enum to choose single vs double null divertor area calculation.
process/core/init.py	Casts i_single_null to the enum for initialization-time configuration checks.

Comments suppressed due to low confidence (2)

process/models/build.py:183

• i_single_null is only assigned inside the if output: block, but it is later used unconditionally (e.g., the divertor coil vertical location logic). When output is False, this will raise UnboundLocalError. Define/cast i_single_null before the if output: so it is always available.

            i_single_null = DivertorNumberModels(physics_variables.i_single_null)
            if i_single_null == DivertorNumberModels.DOUBLE_NULL:

process/models/divertor.py:189

• If i_single_null is not SINGLE_NULL or DOUBLE_NULL, neither branch assigns areadv, but it is used immediately afterwards (pflux_div_heat_load_mw calculation), which will raise UnboundLocalError. Add an explicit else branch that raises ProcessValueError/ProcessValidationError (or otherwise handles unexpected values) so invalid inputs fail with a clear error.

        elif i_single_null == DivertorNumberModels.DOUBLE_NULL:
            areadv = 2.0 * (a1 + a2 + a3)

        if self.data.divertor.i_div_heat_load == 1:
            self.data.divertor.pflux_div_heat_load_mw = p_plasma_separatrix_mw / areadv

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.