desc.magnetic_fields.FreeSurfaceOuterField

class desc.magnetic_fields.FreeSurfaceOuterField(surface, M, N, sym=None, M_coil=None, N_coil=None, sym_coil=None, B_coil=None, Y_coil=None, I_plasma=0.0, I_sheet=0.0)Source

Compute field on outer plasma for free surface.

Implements the interior Dirichlet formulation in multiply connected geometry described in [1]. For this formulation, Phi_tilde represents the globally defined boundary density Φ̃ used in the Dirichlet integral equation, while B0 supplies the physical harmonic field carrying the prescribed periods.

Parameters:

• surface (Surface) – Geometry defining ∂𝒳.

• M (int) – Poloidal Fourier resolution to interpolate potential on ∂𝒳.

• N (int) – Toroidal Fourier resolution to interpolate potential on ∂𝒳.

• sym (str) – Symmetry for the Fourier basis interpolating the globally defined boundary density. Default is sin when the surface is stellarator symmetric and False otherwise.

• M_coil (int) – Poloidal Fourier resolution of the globally defined remainder of the coil potential on ∂𝒳. Default is M.

• N_coil (int) – Toroidal Fourier resolution of the globally defined remainder of the coil potential on ∂𝒳. Default is N.

• sym_coil (str) – Symmetry for Fourier basis interpolating the globally defined remainder of the coil potential. Default is sym.

• B_coil (_MagneticField) – Magnetic field from coil current sources. This must be smooth and divergence free for correctness.

• Y_coil (float) – Net poloidal current determining circulation of coil field. Default is to compute from B_coil.

• I_plasma (float) – Net toroidal plasma current determining a circulation of Φ. Default is zero. The physical representative is built from a linked filament inferred from surface.

• I_sheet (float) – Net toroidal sheet current determining a circulation of Φ. Default is zero. The physical representative is built from a linked filament inferred from surface.

References

[1]

Unalmis et al. New high-order accurate free surface stellarator equilibria optimization and boundary integral methods in DESC.

Methods

change_resolution(*args, **kwargs)	Change the maximum poloidal and toroidal resolution.
compute(names, grid[, params, transforms, ...])	Compute the quantity given by name on grid.
constant_offset_surface(offset[, grid, M, ...])	Create a new FourierRZToroidalSurface with constant offset from self.
copy([deepcopy])	Return a (deep)copy of this object.
equiv(other)	Compare equivalence between DESC objects.
from_input_file(path, **kwargs)	Create a surface from Fourier coefficients in a DESC or VMEC input file.
from_qp_model([major_radius, aspect_ratio, ...])	Create a surface from a near-axis model for quasi-poloidal symmetry.
from_shape_parameters([major_radius, ...])	Create a surface using a generalized Miller parameterization.
from_values(coords, theta[, zeta, M, N, ...])	Create a surface from given R,Z coordinates in real space.
get_axis()	Get the axis of the surface.
get_coeffs(m[, n])	Get Fourier coefficients for given mode number(s).
load(load_from[, file_format])	Initialize from file.
pack_params(p)	Convert a dictionary of parameters into a single array.
save(file_name[, file_format, file_mode])	Save the object.
set_coeffs(m[, n, R, Z])	Set specific Fourier coefficients.
unpack_params(x)	Convert a single array of concatenated parameters into a dictionary.

Attributes

B0	Complete auxiliary field, including the I and Y periods.
B0_base	User-supplied field excluding the built period fields.
I	Net toroidal-current period in T m.
L	Maximum radial mode number.
M	Maximum poloidal mode number.
M_Phi_tilde	Poloidal resolution of the potential remainder.
M_varphi_tilde	Poloidal resolution of tilde-varphi.
N	Maximum toroidal mode number.
NFP	Number of (toroidal) field periods.
N_Phi_tilde	Toroidal resolution of the potential remainder.
N_varphi_tilde	Toroidal resolution of tilde-varphi.
Phi_tilde_basis	Basis for the globally defined potential remainder.
R_basis	Spectral basis for R.
R_lmn	Spectral coefficients for R.
Y	Net poloidal-current period in T m.
Z_basis	Spectral basis for Z.
Z_lmn	Spectral coefficients for Z.
dim_x	total number of optimizable parameters.
dimensions	dictionary of integers of sizes of each optimizable parameter.
name	Name of the surface.
optimizable_params	string names of parameters that have been declared optimizable.
params_dict	dictionary of arrays of optimizable parameters.
rho	Flux surface label.
surface	Surface geometry defining boundary.
sym	Whether the surface is stellarator symmetric.
sym_Phi_tilde	Symmetry of the potential remainder (no symmetry if False).
sym_varphi_tilde	Symmetry of tilde-varphi (no symmetry if False).
varphi_tilde_basis	Basis for globally defined coil-potential remainder.
x_idx	arrays of indices for each parameter in concatenated array.