desc.coils.FourierXYZCoil

class desc.coils.FourierXYZCoil(current=1, X_n=[0, 10, 2], Y_n=[0, 0, 0], Z_n=[-2, 0, 0], modes=None, name='')Source 

Coil parameterized by fourier series for X,Y,Z in terms of arbitrary angle s.

Parameters:

current (float) – current through coil, in Amperes
X_n (array-like) – fourier coefficients for X, Y, Z
Y_n (array-like) – fourier coefficients for X, Y, Z
Z_n (array-like) – fourier coefficients for X, Y, Z
modes (array-like) – mode numbers associated with X_n etc.
name (str) – name for this coil

Examples

from desc.coils import FourierXYZCoil
from desc.grid import LinearGrid
import numpy as np

I = 10
mu0 = 4 * np.pi * 1e-7
R_coil = 10
# circular coil given by X(s) = 10*cos(s), Y(s) = 10*sin(s)
coil = FourierXYZCoil(
    current=I,
    X_n=[0, R_coil, 0],
    Y_n=[0, 0, R_coil],
    Z_n=[0, 0, 0],
    modes=[0, 1, -1],
)
z0 = 10
field_evaluated = coil.compute_magnetic_field(
    np.array([[0, 0, 0], [0, 0, z0]]), basis="rpz"
)
np.testing.assert_allclose(
    field_evaluated[0, :], np.array([0, 0, mu0 * I / 2 / R_coil]), atol=1e-8
)
np.testing.assert_allclose(
    field_evaluated[1, :],
    np.array([0, 0, mu0 * I / 2 * R_coil**2 / (R_coil**2 + z0**2) ** (3 / 2)]),
    atol=1e-8,
)

Methods

`change_resolution`([N])	Change the maximum angular resolution.
`compute`(names[, grid, params, transforms, ...])	Compute the quantity given by name on grid.
`compute_Bnormal`(surface[, eval_grid, ...])	Compute Bnormal from self on the given surface.
`compute_magnetic_field`(coords[, params, ...])	Compute magnetic field at a set of points.
`copy`([deepcopy])	Return a (deep)copy of this object.
`equiv`(other)	Compare equivalence between DESC objects.
`flip`([normal])	Flip the curve about the plane with specified normal.
`from_values`(current, coords[, N, s, basis, name])	Fit coordinates to FourierXYZCoil representation.
`get_coeffs`(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.
`rotate`([axis, angle])	Rotate the curve by a fixed angle about axis in X, Y, Z coordinates.
`save`(file_name[, file_format, file_mode])	Save the object.
`save_BNORM_file`(surface, fname[, basis_M, ...])	Create BNORM-style .txt file containing Bnormal Fourier coefficients.
`save_mgrid`(path, Rmin, Rmax, Zmin, Zmax[, ...])	Save the magnetic field to an mgrid NetCDF file in "raw" format.
`set_coeffs`(n[, X, Y, Z])	Set specific Fourier coefficients.
`to_FourierXYZ`([N, grid, s, name])	Convert coil to FourierXYZCoil representation.
`to_SplineXYZ`([knots, grid, method, name])	Convert coil to SplineXYZCoil.
`translate`([displacement])	Translate the curve by a rigid displacement in X, Y, Z.
`unpack_params`(x)	Convert a single array of concatenated parameters into a dictionary.

Attributes

`N`	Maximum mode number.
`X_basis`	Spectral basis for X Fourier series.
`X_n`	Spectral coefficients for X.
`Y_basis`	Spectral basis for Y Fourier series.
`Y_n`	Spectral coefficients for Y.
`Z_basis`	Spectral basis for Z Fourier series.
`Z_n`	Spectral coefficients for Z.
`current`	Current passing through the coil, in Amperes.
`dim_x`	total number of optimizable parameters.
`dimensions`	dictionary of integers of sizes of each optimizable parameter.
`name`	Name of the curve.
`optimizable_params`	string names of parameters that have been declared optimizable.
`params_dict`	dictionary of arrays of optimizable parameters.
`rotmat`	Rotation matrix of curve in X, Y, Z.
`shift`	Displacement of curve in X, Y, Z.
`x_idx`	arrays of indices for each parameter in concatenated array.