Move fw surface loads to class

[chris-ashe]

This pull request primarily fixes a variable naming typo (plfux_plasma_surface_neutron_avg_mw → pflux_plasma_surface_neutron_avg_mw) throughout the codebase, and refactors the calculation and assignment of first wall neutron and photon power fluxes. The logic for these calculations is moved out of physics.py and consolidated within fw.py, simplifying and centralizing the power flux computations. Additionally, related output and plotting code is updated to use the corrected variable name.

Refactor and relocation of first wall power flux calculations:

• Moved the calculation of pflux_fw_neutron_mw and pflux_fw_rad_mw from physics.py to fw.py, consolidating the logic and simplifying the code structure. The new implementation uses a more unified approach for both neutron and photon wall loads, removing configuration-specific branches from physics.py.

✅ - Within fw.py

        if physics_variables.i_pflux_fw_neutron == 1:
            physics_variables.pflux_fw_neutron_mw = (
                physics_variables.ffwal
                * physics_variables.pflux_plasma_surface_neutron_avg_mw
            )
        else:
            physics_variables.pflux_fw_neutron_mw = (
                physics_variables.p_neutron_total_mw / first_wall_variables.a_fw_total
            )

        if physics_variables.i_pflux_fw_neutron == 1:
            physics_variables.pflux_fw_rad_mw = (
                physics_variables.ffwal
                * physics_variables.p_plasma_rad_mw
                / physics_variables.a_plasma_surface
            )
        else:
            physics_variables.pflux_fw_rad_mw = (
                physics_variables.p_plasma_rad_mw / build_variables.a_fw_total
            )

        constraint_variables.pflux_fw_rad_max_mw = (
            physics_variables.pflux_fw_rad_mw * constraint_variables.f_fw_rad_max
        )

🟥 - In physics.py with redundant calculation already done by apply_first_wall_coverage_factors()

# Nominal mean neutron wall load on entire first wall area including divertor and beam holes
        # Note that 'a_fw_total' excludes these, so they have been added back in.
        if physics_variables.i_pflux_fw_neutron == 1:
            physics_variables.pflux_fw_neutron_mw = (
                physics_variables.ffwal
                * physics_variables.p_neutron_total_mw
                / physics_variables.a_plasma_surface
            )
        else:
            if divertor_variables.n_divertors == 2:
                # Double null configuration
                physics_variables.pflux_fw_neutron_mw = (
                    (
                        1.0e0
                        - fwbs_variables.f_a_fw_outboard_hcd
                        - 2.0e0 * fwbs_variables.f_ster_div_single
                    )
                    * physics_variables.p_neutron_total_mw
                    / build_variables.a_fw_total
                )
            else:
                # Single null Configuration
                physics_variables.pflux_fw_neutron_mw = (
                    (
                        1.0e0
                        - fwbs_variables.f_a_fw_outboard_hcd
                        - fwbs_variables.f_ster_div_single
                    )
                    * physics_variables.p_neutron_total_mw
                    / build_variables.a_fw_total
                )

# MDK
        # Nominal mean photon wall load on entire first wall area including divertor and beam holes
        # Note that 'a_fw_total' excludes these, so they have been added back in.
        if physics_variables.i_pflux_fw_neutron == 1:
            physics_variables.pflux_fw_rad_mw = (
                physics_variables.ffwal
                * physics_variables.p_plasma_rad_mw
                / physics_variables.a_plasma_surface
            )
        else:
            if divertor_variables.n_divertors == 2:
                # Double Null configuration in - including SoL radiation
                physics_variables.pflux_fw_rad_mw = (
                    (
                        1.0e0
                        - fwbs_variables.f_a_fw_outboard_hcd
                        - 2.0e0 * fwbs_variables.f_ster_div_single
                    )
                    * physics_variables.p_plasma_rad_mw
                    / build_variables.a_fw_total
                    + (
                        1.0e0
                        - fwbs_variables.f_a_fw_outboard_hcd
                        - 2.0e0 * fwbs_variables.f_ster_div_single
                    )
                    * physics_variables.rad_fraction_sol
                    * physics_variables.p_plasma_separatrix_mw
                    / (build_variables.a_fw_total)
                )
            else:
                # Single null configuration - including SoL radaition
                physics_variables.pflux_fw_rad_mw = (
                    (
                        1.0e0
                        - fwbs_variables.f_a_fw_outboard_hcd
                        - fwbs_variables.f_ster_div_single
                    )
                    * physics_variables.p_plasma_rad_mw
                    / build_variables.a_fw_total
                    + (
                        1.0e0
                        - fwbs_variables.f_a_fw_outboard_hcd
                        - fwbs_variables.f_ster_div_single
                    )
                    * physics_variables.rad_fraction_sol
                    * physics_variables.p_plasma_separatrix_mw
                    / build_variables.a_fw_total
                )

        constraint_variables.pflux_fw_rad_max_mw = (
            physics_variables.pflux_fw_rad_mw * constraint_variables.f_fw_rad_max
        )

Variable name correction and consistency:

• Fixed the typo in the variable name from plfux_plasma_surface_neutron_avg_mw to pflux_plasma_surface_neutron_avg_mw across all relevant files and function signatures, including initialization and output routines.

Output and plotting updates:

• Updated output and plotting code to reference the corrected variable name, ensuring that results and visualizations use the consistent and correct identifier.

Code cleanup:

• Removed unused imports from physics.py and updated import statements to reflect the new locations of relevant calculations.

These changes improve code clarity, maintainability, and correctness regarding the calculation and reporting of first wall neutron and photon fluxes.## 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]

Codecov Report

❌ Patch coverage is 15.00000% with 17 lines in your changes missing coverage. Please review.
✅ Project coverage is 46.87%. Comparing base (bb358d5) to head (e53191c).

Files with missing lines	Patch %	Lines
process/models/fw.py	6.25%	15 Missing ⚠️
process/models/physics/physics.py	0.00%	1 Missing ⚠️
process/output.py	0.00%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #4095   +/-   ##
=======================================
  Coverage   46.86%   46.87%           
=======================================
  Files         136      136           
  Lines       29228    29227    -1     
=======================================
+ Hits        13698    13699    +1     
+ Misses      15530    15528    -2     

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[timothy-nunn]

Can you move the outputting of pflux_fw_rad_mw, pflux_fw_neutron_mw, and p_fw_alpha_mw from physics to the first wall.

[chris-ashe]

Can you move the outputting of pflux_fw_rad_mw, pflux_fw_neutron_mw, and p_fw_alpha_mw from physics to the first wall.

Have added a new output for surface loads in fw.py

[timothy-nunn]

Suggested change

	# ==============================
	# First wall power fluxes
	# ==============================

We are trying to rid PROCESS of comment blocks like this

[timothy-nunn]

Before there was an if statement for the number of divertors, why has this changed?

PROCESS/process/models/physics/physics.py

Lines 2284 to 2312 in 73e929a

	if physics_variables.i_pflux_fw_neutron == 1:
	physics_variables.pflux_fw_neutron_mw = (
	physics_variables.ffwal
	* physics_variables.p_neutron_total_mw
	/ physics_variables.a_plasma_surface
	)
	else:
	if divertor_variables.n_divertors == 2:
	# Double null configuration
	physics_variables.pflux_fw_neutron_mw = (
	(
	1.0e0
	- fwbs_variables.f_a_fw_outboard_hcd
	- 2.0e0 * fwbs_variables.f_ster_div_single
	)
	* physics_variables.p_neutron_total_mw
	/ build_variables.a_fw_total
	)
	else:
	# Single null Configuration
	physics_variables.pflux_fw_neutron_mw = (
	(
	1.0e0
	- fwbs_variables.f_a_fw_outboard_hcd
	- fwbs_variables.f_ster_div_single
	)
	* physics_variables.p_neutron_total_mw
	/ build_variables.a_fw_total
	)

[timothy-nunn]

Again, no if for the different divertor configurations, why?

Before:

PROCESS/process/models/physics/physics.py

Lines 2591 to 2628 in 73e929a

	if divertor_variables.n_divertors == 2:
	# Double Null configuration in - including SoL radiation
	physics_variables.pflux_fw_rad_mw = (
	(
	1.0e0
	- fwbs_variables.f_a_fw_outboard_hcd
	- 2.0e0 * fwbs_variables.f_ster_div_single
	)
	* physics_variables.p_plasma_rad_mw
	/ build_variables.a_fw_total
	+ (
	1.0e0
	- fwbs_variables.f_a_fw_outboard_hcd
	- 2.0e0 * fwbs_variables.f_ster_div_single
	)
	* physics_variables.rad_fraction_sol
	* physics_variables.p_plasma_separatrix_mw
	/ (build_variables.a_fw_total)
	)
	else:
	# Single null configuration - including SoL radaition
	physics_variables.pflux_fw_rad_mw = (
	(
	1.0e0
	- fwbs_variables.f_a_fw_outboard_hcd
	- fwbs_variables.f_ster_div_single
	)
	* physics_variables.p_plasma_rad_mw
	/ build_variables.a_fw_total
	+ (
	1.0e0
	- fwbs_variables.f_a_fw_outboard_hcd
	- fwbs_variables.f_ster_div_single
	)
	* physics_variables.rad_fraction_sol
	* physics_variables.p_plasma_separatrix_mw
	/ build_variables.a_fw_total
	)

[timothy-nunn]

Are these two really constraint_variables or can they be moved into the first wall data structure?