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.
eq(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.
rotate([axis, angle])	Rotate the curve by a fixed angle about axis in xyz 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.
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.

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.
name	Name of the curve.