helicon.validate
Validation suite: physics benchmark cases and comparison reporting.
Runner
helicon.validate.runner.run_validation(*, cases=None, output_base='results/validation', run_simulations=True)
Run the validation suite.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
cases
|
list of str
|
Case names to run. None = run all. |
None
|
output_base
|
path
|
Base directory for validation output. |
'results/validation'
|
run_simulations
|
bool
|
If True, actually run WarpX simulations. If False, only evaluate existing output (useful for re-analysis). |
True
|
Source code in src/helicon/validate/runner.py
Validation Cases
helicon.validate.cases.free_expansion.FreeExpansionCase
Free expansion into vacuum — momentum conservation test.
A single-coil solenoid nozzle with a low-temperature plasma injected at the throat. The total axial momentum of the system (particles + fields) must be conserved to within 0.1%.
Functions
evaluate(output_dir)
staticmethod
Evaluate the validation case from simulation output.
Checks that total axial momentum is conserved to < 0.1%.
Source code in src/helicon/validate/cases/free_expansion.py
get_config()
staticmethod
Return the simulation configuration for this case.
Source code in src/helicon/validate/cases/free_expansion.py
helicon.validate.cases.merino_ahedo.MerinoAhedoCase
Merino & Ahedo (2016) collisionless magnetic nozzle.
A converging-diverging nozzle with fully kinetic ions and electrons. Tests that Helicon reproduces the published detachment efficiency trend with plasma β at the throat.
Three sub-cases at β = 0.01, 0.05, 0.10 are run and compared against the published values.
Functions
evaluate(output_dir)
staticmethod
Evaluate by comparing η_d vs β against published values.
Expects sub-directories beta_0.01, beta_0.05, beta_0.10 under output_dir, or evaluates a single run if those don't exist.
Source code in src/helicon/validate/cases/merino_ahedo.py
get_config()
staticmethod
get_configs()
staticmethod
Return configs for each β value.
Source code in src/helicon/validate/cases/merino_ahedo.py
helicon.validate.cases.vasimr_plume.VASIMRPlumeCase
VASIMR VX-200 plume benchmark (Olsen et al. 2015).
Tests thrust efficiency and plume divergence angle against published experimental measurements at 200 kW operating point.
Functions
evaluate(output_dir)
staticmethod
Compare simulated plume metrics against VX-200 reference data.
Source code in src/helicon/validate/cases/vasimr_plume.py
get_config()
staticmethod
Return the VASIMR-equivalent simulation configuration.
The VX-200 uses a helicon + ICH RF system. We model the nozzle region only, with the plasma injected at the magnetic throat.
Parameters approximate the VX-200 geometry and plasma conditions from Olsen (2015): B_throat ≈ 0.5 T, argon plasma.
Source code in src/helicon/validate/cases/vasimr_plume.py
helicon.validate.cases.resistive_dimov.ResistiveDimovCase
Resistive detachment threshold validation (Moses 1991, Dimov 2005).
Configures a nozzle near the resistive detachment threshold and verifies that the electron magnetization parameter Ω_e τ_e computed by Helicon is consistent with the theoretical onset criterion Ω_e τ_e ≈ 1.
Functions
evaluate(output_dir)
staticmethod
Check that Ω_e τ_e at the throat matches the detachment threshold.
Source code in src/helicon/validate/cases/resistive_dimov.py
get_config()
staticmethod
Return the resistive-detachment-onset configuration.
Parameters chosen so that Ω_e τ_e ≈ 1 at the throat, placing the simulation near the resistive detachment boundary. Uses a lower B-field and moderate density to achieve Ω_e τ_e ~ O(1).
Source code in src/helicon/validate/cases/resistive_dimov.py
hall_parameter_threshold(B_T, T_e_eV, n_m3, ln_lambda=15.0)
staticmethod
Compute electron Hall parameter Ω_e τ_e analytically.
Uses the Spitzer electron-ion collision frequency: ν_ei = n e^4 ln_Λ / (3 ε₀² √(2π) m_e^(1/2) (k_B T_e)^(3/2))
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
B_T
|
float
|
Magnetic field [T]. |
required |
T_e_eV
|
float
|
Electron temperature [eV]. |
required |
n_m3
|
float
|
Plasma density [m^-3]. |
required |
ln_lambda
|
float
|
Coulomb logarithm. |
15.0
|
Returns:
| Name | Type | Description |
|---|---|---|
omega_tau |
float
|
Hall parameter Ω_e / ν_ei. |
Source code in src/helicon/validate/cases/resistive_dimov.py
Report
helicon.validate.report.generate_html_report(results, output_dir)
Generate a self-contained HTML validation report.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
results
|
list of dict
|
Each dict has keys: case_name, passed, metrics, tolerances, description. |
required |
output_dir
|
str or Path
|
Directory where validation_report.html will be written. |
required |
Returns:
| Type | Description |
|---|---|
Path
|
Path to the generated HTML file. |
Source code in src/helicon/validate/report.py
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helicon.validate.report.save_validation_plots(validation_report_results, output_dir)
Save comparison plots for each validation case.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
validation_report_results
|
list of dict
|
Each dict has keys: case_name, passed, metrics, tolerances, description. |
required |
output_dir
|
str or Path
|
Directory for saved figures. |
required |
Returns:
| Type | Description |
|---|---|
list of Path
|
Paths to the saved PNG files. |