desc.plotting.plot_field_lines_sfl

desc.plotting.plot_field_lines_sfl(eq, rho, seed_thetas=0, phi_start=0, phi_end=6.283185307179586, dphi=0.01, ax=None, return_data=False, **kwargs)[source]

Plots field lines on specified flux surface.

Traces field lines at specified initial vartheta (\(\\vartheta\)) seed locations, then plots them. Field lines traced by first finding the corresponding straight-field-line (SFL) coordinates \((\\rho,\\vartheta,\\phi)\) for each field line, then converting those to the computational \((\\rho,\\theta,\\phi)\) coordinates, then finally computing from those the toroidal \((R,\\phi,Z)\) coordinates of each field line.

The SFL angle coordinates are found with the SFL relation:

\(\\vartheta = \\iota \\phi + \\vartheta_0\)

Parameters:

  • eq (Equilibrium) – Object from which to plot.

  • rho (float) – Flux surface to trace field lines at.

  • seed_thetas (float or array-like of floats) – Poloidal positions at which to seed magnetic field lines. If array-like, will plot multiple field lines.

  • phi_start (float) – Toroidal angle to integrate field line from, in radians. Default is 0.

  • phi_end (float) – Toroidal angle to integrate field line until, in radians. Default is 2*pi.

  • dphi (float) – spacing in phi to sample field lines along, in radians. Default is 1e-2.

  • ax (matplotlib AxesSubplot, optional) – Axis to plot on. if True, return the data plotted as well as fig,ax

  • return_data (bool) – if True, return the data plotted as well as fig,ax

  • **kwargs (fig,ax and plotting properties) –

    Specify properties of the figure, axis, and plot appearance e.g.:

    plot_X(figsize=(4,6))

    Valid keyword arguments are:

    figsize: tuple of length 2, the size of the figure (to be passed to matplotlib)

Returns:

  • fig (matplotlib.figure.Figure) – Figure being plotted to.

  • ax (matplotlib.axes.Axes or ndarray of Axes) – Axes being plotted to.

  • plot_data (dict) – Dict containing the R,phi,Z coordinates of each field line traced. Dictionary entries are lists corresponding to the field lines for each seed_theta given. Also contains the scipy IVP solutions for info on how each line was integrated

Examples

../../_images/DSHAPE_field_lines_plot.png 
from desc.plotting import plot_field_lines_sfl
import desc.examples
import numpy as np
eq = desc.examples.get("DSHAPE")
seed_thetas=np.linspace(0, 2 * np.pi, 3,endpoint=False)
fig, ax, _ = plot_field_lines_sfl(
    eq, rho=1,seed_thetas=seed_thetas , phi_end=2 * np.pi
)