Skip to content

EEDF_INTEGRATION.md

Latest commit

 

History

History
109 lines (92 loc) · 4.57 KB

EEDF_INTEGRATION.md

File metadata and controls

109 lines (92 loc) · 4.57 KB
Raw

Note

Status: Verified Validated against codebase (Feb 2026).

EEDF Integration Summary

Date: December 8, 2025
Branch: feature/loki-b-eedf-integration
Status: Functional, testing in progress

Overview

Successfully integrated LoKI-B Boltzmann solver for non-Maxwellian electron energy distribution function (EEDF) calculations in zdplasmapy. This enables accurate electron impact rate coefficients based on cross-section data instead of assuming Maxwellian distributions.

Key Components

1. EEDF Solver Backend (src/eedf_solver.py)

  • Architecture: Pluggable Protocol-based system supporting multiple solvers
  • Current Backend: LoKI-B (C++ Boltzmann solver)
  • Future Support: BOLSIG+, Bolos planned
  • Features:
    • Auto-detection of LoKI binary in external/LoKI-B-cpp/build/
    • Cross-section file resolution (LXCat format)
    • Database file auto-detection (masses, frequencies, etc.)
    • Input/output translation between zdplasmapy and LoKI formats
    • Process ID matching for reaction disambiguation

2. Chemistry Parser Updates (src/chemistry_parser.py)

  • New Section: reactions_eedf in chemistry.yml files
  • Structure: 
    reactions_eedf:
  file: "external/LoKI-B-cpp/input/Oxygen/O2_LXCat.txt"
  reference: "Phelps 1985, www.LXCat.net"
  reactions:
    - {formula: "e + O2 -> e + O2", process: "O2 -> O2", energy_loss: ..., type: "elastic"}
    - {formula: "e + O2 -> O2+ + 2e", process: "O2 -> O2^+", energy_loss: 12.1, type: "ionization"}
  • Features:
    • Project-relative cross-section file paths
    • Process ID field for matching reactions to cross-section data
    • Mixed mode: EEDF reactions (use_eedf: True) + analytic reactions (use_eedf: False)

3. Configuration System (src/config_loader.py)

  • Location: EEDF settings in additional_parameters.eedf
  • Schema: 
    additional_parameters:
  eedf:
    enabled: true
    backend: loki
    timestamps: [0.0, 1.0e-6, 5.0e-6, 1.0e-5, ...]
    options: {}
  • Timestamp Control: EEDF calculated only at specified times (not every step)

4. Global Model Integration (src/global_model.py)

  • Modification: Added EEDF calls in _ode_system() method
  • Logic:
    • Check if current time matches a timestamp (within tolerance)
    • Build EEDF request with current plasma parameters
    • Call LoKI-B backend
    • Cache results to avoid redundant calls
    • Use EEDF-derived rate coefficients for electron-impact reactions
  • Attributes: eedf_enabled, eedf_backend, eedf_timestamps, eedf_results

5. External Dependencies

  • LoKI-B Installation: external/setup_loki_b.sh script
    • Auto-clones from GitHub
    • Detects Ninja build system for faster compilation
    • Pure Eigen backend (no OpenBLAS/MKL required by default)
    • Binary location: external/LoKI-B-cpp/build/app/loki
  • Cross-sections: LXCat format in external/LoKI-B-cpp/input/<Species>/
  • Database Files: masses.txt, harmonicFrequencies.txt, etc.

6. Test Case (cases/testEEDF/)

  • Chemistry: Oxygen plasma (based on Chung 1999)
  • Species: O2, O2+, O, O+, O-, e
  • Reactions:
    • 2 EEDF-driven (elastic, ionization) from cross-sections
    • 11 analytic (attachment, recombination, dissociation, wall losses)
  • Configuration: 1 Torr, 10W power, cylindrical geometry
  • Purpose: Validation of EEDF integration, template for future cases

Implementation Details

Cross-Section File Resolution

  1. Chemistry parser reads file path from reactions_eedf section
  2. Path resolved relative to project root
  3. EEDF backend receives absolute path to cross-section file
  4. LoKI loads cross-sections and maps to processes via process field

Timestamp-Based Execution

  • Rationale: EEDF calculation is expensive, only needed when conditions change significantly
  • Mechanism: User specifies timestamps in config (e.g., [0, 1e-6, 1e-5, ...])
  • Tolerance: abs(t - timestamp) < 1e-9 for floating-point comparison
  • Caching: Results stored in self.eedf_results dict keyed by timestamp

LoKI Input Format

  • Format: YAML-like with % comments (not standard YAML)
  • Sections: workingConditions, electronKinetics, chemistry, output
  • Translation: _build_loki_input() converts zdplasmapy request to LoKI format
  • Ground States: Species mapping (Ar→Ar(1S0), O2→O2(X), etc.)

Output Parsing

  • Preferred: JSON output (output.json with energyGrid, eedf fields)
  • Fallback: Text output (eedf.txt two-column format)
  • Normalization: Backend returns {energy_grid: [...], eedf: [...], diagnostics: {...}}