| --- |
| license: cc-by-4.0 |
| language: |
| - en |
| pretty_name: SII Stellarator Configuration Dataset |
| tags: |
| - fusion |
| - stellarator |
| - quasi-isodynamic |
| - scientific-machine-learning |
| - tabular |
| --- |
| |
| # SII Stellarator Configuration Dataset |
|
|
| **Wenyang Li** |
|
|
| [**Shanghai Innovation Institute**](http://www.sii.edu.cn) | PhD student |
|
|
| [AI-Driven Controlled Fusion Simulation, Control & Design Lab](https://github.com/SII-AI4Fusion) |
|
|
| - **Phone**: [+86-156-2003-5216](tel:+86-156-2003-5216) |
| - **Email**: [lwydsg@mail.nankai.edu.cn](mailto:lwydsg@mail.nankai.edu.cn) |
|
|
| --- |
|
|
| ## Overview |
|
|
| This directory hosts a **stellarator configuration dataset grouped by number |
| of field periods (nfp)**. Each sample keeps only three things: |
| **Fourier boundary coefficients, nfp, and 9 VMEC evaluation metrics** — |
| every field is guaranteed to be non-`None` / non-`NaN`. |
|
|
| Design goals: |
|
|
| 1. **Simplified content** — keep only the Fourier coefficients and the 9 |
| VMEC metrics that configuration-design optimization actually needs; all |
| other construction parameters / diagnostics / multi-beta-branch |
| evaluations are stripped out. |
| 2. **Ready for future growth** — more QI (Quasi-Isodynamic) configurations |
| will be folded in later, so a unified, clean, schema-stable baseline |
| makes that painless. |
|
|
| ## Source |
|
|
| Derived from a local copy of |
| [proxima-fusion/constellaration](https://huggingface.co/datasets/proxima-fusion/constellaration), |
| covering `n_field_periods` (nfp) = 1–5. The upstream library has broad |
| coverage but not every row has complete VMEC evaluation results; this |
| dataset keeps **only rows where every field is fully valid**. |
|
|
| ## File layout |
|
|
| One file per nfp. The filename embeds the number of retained samples |
| `n{count}`: |
|
|
| | File | Samples | Note | |
| | --- | --- | --- | |
| | `nfp1_n14607.parquet` | 14,607 | nfp = 1 | |
| | `nfp2_n19945.parquet` | 19,945 | nfp = 2 | |
| | `nfp3_n68191.parquet` | 68,191 | nfp = 3 | |
| | `nfp4_n27798.parquet` | 27,798 | nfp = 4 | |
| | `nfp5_n28144.parquet` | 28,144 | nfp = 5 | |
| | **Total** | **158,685** | | |
|
|
| Parquet files use snappy compression with a flat column layout — they can |
| be loaded column-wise directly. |
|
|
| ## Fields |
|
|
| Each row (one sample) has three groups of fields: |
|
|
| ### 1. Field-period count `nfp` |
|
|
| - Column: `boundary.n_field_periods` |
| - Type: integer |
| - Meaning: number of toroidal field periods |
| - Values present in this dataset: 1, 2, 3, 4, 5 |
|
|
| ### 2. Fourier boundary coefficients `boundary.r_cos` / `boundary.z_sin` |
|
|
| - Type: 5×9 float matrix (`list<list<double>>`) |
| - Meaning: Fourier expansion coefficients of the stellarator boundary |
| surface along the `(θ, φ)` periodic directions. `r_cos` is the cosine |
| component of R; `z_sin` is the sine component of Z (the configuration is |
| stellarator-symmetric, so only these two terms are retained). |
| - Shape convention: row index corresponds to the poloidal mode `m` |
| (0…4, 5 rows); column index corresponds to the toroidal mode `n` |
| (−4…+4, 9 columns). |
|
|
| ### 3. VMEC evaluation metrics `metrics.*` |
| |
| | Column | Meaning | |
| | --- | --- | |
| | `metrics.aspect_ratio` | Aspect ratio | |
| | `metrics.edge_rotational_transform_over_n_field_periods` | Edge iota / nfp (**no abs applied** — original sign preserved) | |
| | `metrics.average_triangularity` | Average triangularity | |
| | `metrics.max_elongation` | Maximum elongation | |
| | `metrics.edge_magnetic_mirror_ratio` | Edge magnetic mirror ratio | |
| | `metrics.vacuum_well` | Vacuum magnetic well | |
| | `metrics.minimum_normalized_magnetic_gradient_scale_length` | Minimum normalized magnetic gradient scale length | |
| | `metrics.qi` | Quasi-isodynamic residual (**no log10 applied** — raw value) | |
| | `metrics.flux_compression_in_regions_of_bad_curvature` | Flux compression in regions of bad curvature | |
| |
| > For generality, `iota` is not abs-ed and `qi` is not log10-transformed — |
| > raw values are stored; downstream code applies whatever transform it |
| > needs. |
| |
| ## Full schema |
| |
| Flat column names for straightforward column-wise access: |
| |
| | Column | Type | |
| | --- | --- | |
| | `boundary.n_field_periods` | `int64` | |
| | `boundary.r_cos` | `list<list<double>>` (5×9) | |
| | `boundary.z_sin` | `list<list<double>>` (5×9) | |
| | `metrics.aspect_ratio` | `double` | |
| | `metrics.edge_rotational_transform_over_n_field_periods` | `double` | |
| | `metrics.average_triangularity` | `double` | |
| | `metrics.max_elongation` | `double` | |
| | `metrics.edge_magnetic_mirror_ratio` | `double` | |
| | `metrics.vacuum_well` | `double` | |
| | `metrics.minimum_normalized_magnetic_gradient_scale_length` | `double` | |
| | `metrics.qi` | `double` | |
| | `metrics.flux_compression_in_regions_of_bad_curvature` | `double` | |
| |
| ## Data-quality guarantee |
| |
| Every sample satisfies: |
| |
| 1. `nfp` is neither `None` nor `NaN`; |
| 2. The entire 5×9 matrices of `boundary.r_cos` and `boundary.z_sin` contain |
| no `None` / `NaN`; |
| 3. All **9 VMEC metrics** above are non-`None` and non-`NaN`. |
| |
| Any sample failing any of these conditions was removed before inclusion. |
| |
