InnerLayer.SLAYER - DOCS - 🌱 Describe chi_tor as the toroidal momentum diffusivity, not a heat diffusivity

[d-burg]

Release note

• Audience: users
• Numerical impact: none (harness @ b2d00c8)
• Migration: none

The chi_tor docstrings now say what it is: χ_φ, the anomalous perpendicular ion momentum diffusivity. It enters the SLAYER layer model through the momentum Prandtl number P_φ = τ_R·χ_φ/r_s² (Burgess et al. 2026, Table 1). They previously called it a toroidal heat diffusivity. Docstrings only; no code changes.

Regression report

regress --cases diiid_slayer_n1 --refs 9ff10c711,b2d00c886 --force on feynman (SLURM, 8 threads; develop vs head, both fresh, manifest pinned).

Regression Report: diiid_slayer_n1
========================================================================================================================================================
Ref 1: 9ff10c711990047a62970709b98fe1b7fc9f053b  @ 9ff10c711 (2026-09-25)
       env: julia 1.11.9, x86_64-linux-gnu, manifest f826ee26 (pinned), 8 threads/8 BLAS
Ref 2: b2d00c88662ffa5e6a7a12154bb5eb6b17a54b9b  @ b2d00c886 (2026-09-25)
       env: julia 1.11.9, x86_64-linux-gnu, manifest f826ee26 (pinned), 8 threads/8 BLAS
--------------------------------------------------------------------------------------------------------------------------------------------------------
Quantity                            9ff10c711990047a62970709b98fe1b7fc9f053b  b2d00c88662ffa5e6a7a12154bb5eb6b17a54b9b  Diff               Status       
--------------------------------------------------------------------------------------------------------------------------------------------------------
SLAYER surface indices              [6 elem]                                  [6 elem]                                  0.0e+00            OK           
SLAYER poloidal m                   [6 elem]                                  [6 elem]                                  0.0e+00            OK           
SLAYER toroidal n                   [6 elem]                                  [6 elem]                                  0.0e+00            OK           
SLAYER minor radius rs              [6 elem]                                  [6 elem]                                  0.0e+00            OK           
SLAYER r-based shear                [6 elem]                                  [6 elem]                                  0.0e+00            OK           
SLAYER Lundquist S                  [6 elem]                                  [6 elem]                                  0.0e+00            OK           
SLAYER D_norm                       [6 elem]                                  [6 elem]                                  0.0e+00            OK           
SLAYER P_perp                       [6 elem]                                  [6 elem]                                  0.0e+00            OK           
SLAYER tauk                         [6 elem]                                  [6 elem]                                  0.0e+00            OK           
SLAYER iota_e                       [6 elem]                                  [6 elem]                                  0.0e+00            OK           
SLAYER Q_e                          [6 elem]                                  [6 elem]                                  0.0e+00            OK           
SLAYER Q_i                          [6 elem]                                  [6 elem]                                  0.0e+00            OK           
SLAYER Q_root [2/1,3/1,4/1]         [3 elem]                                  [3 elem]                                  5.9e-06            OK           
SLAYER ω_Hz [2/1,3/1,4/1]           [3 elem]                                  [3 elem]                                  6.1e-02            OK           
SLAYER γ_Hz [2/1,3/1,4/1]           [3 elem]                                  [3 elem]                                  1.467e-01 (0.01%)  ** CHANGED **
SLAYER no_root flags [2/1,3/1,4/1]  [3 elem]                                  [3 elem]                                  0.0e+00            OK           
SLAYER enabled flag                 1                                         1                                         0.0e+00            OK           
Runtime (s)                         288.3s                                    262.4s                                                       --           
========================================================================================================================================================
Summary: 1 changed, 16 unchanged

The γ line (0.01 %) is develop's unseeded AMR-triangulation noise; this branch touches no code. The same noise appears on unrelated PRs, and the triangulation is seeded in a separate open PR.

Notes for reviewers

This correction was split off from the regression-harness tolerance PR so that it can be reviewed on its own.

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🤖 Generated with Claude Code

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