essos.mgrid¶

VMEC mgrid read/write helpers for ESSOS coil fields.

The writer mirrors the SIMSOPT MagneticField.to_mgrid convention: fields are evaluated on a cylindrical tensor grid with layout (nphi, nz, nr) and written to VMEC/MAKEGRID-compatible NetCDF files.

Attributes¶

_BIOT_SAVART_PAIR_BUDGET

Classes¶

MGrid

VMEC mgrid data and a JAX-compatible interpolated magnetic field.

Functions¶

`_pad_string`(→ str)
`_unpack`(→ str)
`_interpolate_component`(fields, weights, r, phi, z, *, ...)	Trilinearly interpolate coil-group tables, periodically in phi.
`coils_to_mgrid`(→ MGrid)	Sample a periodic coil field and write a VMEC-compatible mgrid file.

Module Contents¶

essos.mgrid._BIOT_SAVART_PAIR_BUDGET = 4000000¶

essos.mgrid._pad_string(string: str) → str¶

essos.mgrid._unpack(binary_array: Any) → str¶

essos.mgrid._interpolate_component(fields, weights, r, phi, z, *, rmin, rmax, zmin, zmax, nfp)¶: Trilinearly interpolate coil-group tables, periodically in phi.

class essos.mgrid.MGrid¶

Bases: essos.fields.MagneticField

VMEC mgrid data and a JAX-compatible interpolated magnetic field.

B(points) returns Cartesian field vectors. R and Z are clamped to the tabulated bounds; phi is periodic with period 2*pi/nfp. The field is trilinearly interpolated between grid nodes.

nr: int = 51¶

nz: int = 51¶

nphi: int = 24¶

nfp: int = 2¶

rmin: float = 0.2¶

rmax: float = 0.4¶

zmin: float = -0.1¶

zmax: float = 0.1¶

br_arr: Any¶

bp_arr: Any¶

bz_arr: Any¶

coil_names: list[str] = []¶

mode: str = 'N'¶

raw_coil_current: Any¶

__post_init__()¶

property n_ext_cur: int¶

add_field_cylindrical(br: Any, bp: Any, bz: Any, name: str | None = None) → None¶: Append one external-current group in cylindrical components.

property _field_weights¶

property br¶

property bp¶

property bz¶

property bvec¶

b_cyl(r, phi, z)¶: Return (B_R, B_phi, B_Z) at broadcastable cylindrical points.

B(points)¶: Return the interpolated field in Cartesian coordinates.

AbsB(points)¶: Return the field magnitude for each Cartesian point.

sqrtg(points)¶

to_xyz(points)¶

_tree_flatten()¶

classmethod _tree_unflatten(aux, children)¶

write(filename: str | pathlib.Path) → None¶: Write the mgrid to a VMEC-compatible NetCDF file.

classmethod from_file(filename: str | pathlib.Path) → MGrid¶: Read an mgrid NetCDF file.

essos.mgrid.coils_to_mgrid(coils: Any, filename: str | pathlib.Path, *, nr: int = 10, nphi: int = 4, nz: int = 12, rmin: float = 1.0, rmax: float = 2.0, zmin: float = -0.5, zmax: float = 0.5, nfp: int | None = None, name: str = 'essos_coils') → MGrid¶: Sample a periodic coil field and write a VMEC-compatible mgrid file.