API Documentation

Basis

`desc.basis.PowerSeries`(L[, sym])	1D basis set for flux surface quantities.
`desc.basis.FourierSeries`(N[, NFP, sym])	1D basis set for use with the magnetic axis.
`desc.basis.DoubleFourierSeries`(M, N[, NFP, sym])	2D basis set for use on a single flux surface.
`desc.basis.ZernikePolynomial`(L, M[, sym, ...])	2D basis set for analytic functions in a unit disc.
`desc.basis.ChebyshevDoubleFourierBasis`(L, M, N)	3D basis: tensor product of Chebyshev polynomials and two Fourier series.
`desc.basis.FourierZernikeBasis`(L, M, N[, ...])	3D basis set for analytic functions in a toroidal volume.

Coils

`desc.coils.FourierRZCoil`([current, R_n, ...])	Coil parameterized by fourier series for R,Z in terms of toroidal angle phi.
`desc.coils.FourierXYZCoil`([current, X_n, ...])	Coil parameterized by fourier series for X,Y,Z in terms of arbitrary angle phi.
`desc.coils.FourierPlanarCoil`([current, ...])	Coil that lines in a plane.
`desc.coils.SplineXYZCoil`(current, X, Y, Z[, ...])	Coil parameterized by spline points in X,Y,Z.
`desc.coils.CoilSet`(*coils[, name])	Set of coils of different geometry.

Continuation

`desc.continuation.solve_continuation`(eqfam)	Solve for an equilibrium by continuation method.
`desc.continuation.solve_continuation_automatic`(eq)	Solve for an equilibrium using an automatic continuation method.

Derivatives

Note that the derivative module also exposes the Derivative class, which is an alias for AutoDiffDerivative if JAX is installed, or FiniteDiffDerivative if not.

`desc.derivatives.AutoDiffDerivative`(fun[, ...])	Computes derivatives using automatic differentiation with JAX.
`desc.derivatives.FiniteDiffDerivative`(fun[, ...])	Computes derivatives using 2nd order centered finite differences.

Equilibrium

`desc.equilibrium.Equilibrium`([Psi, NFP, L, ...])	Equilibrium is an object that represents a plasma equilibrium.
`desc.equilibrium.EquilibriaFamily`(*args)	EquilibriaFamily stores a list of Equilibria.

Examples

`desc.examples.get`(name[, data])	Get example equilibria and data.
`desc.examples.listall`()	Return a list of examples that DESC has.

Geometry

`desc.geometry.FourierRZCurve`([R_n, Z_n, ...])	Curve parameterized by Fourier series for R,Z in terms of toroidal angle phi.
`desc.geometry.FourierXYZCurve`([X_n, Y_n, ...])	Curve parameterized by Fourier series for X,Y,Z in terms of arbitrary angle phi.
`desc.geometry.FourierPlanarCurve`([center, ...])	Curve that lies in a plane.
`desc.geometry.FourierRZToroidalSurface`([...])	Toroidal surface represented by Fourier series in poloidal and toroidal angles.
`desc.geometry.SplineXYZCurve`(X, Y, Z[, ...])	Curve parameterized by spline knots in X,Y,Z.
`desc.geometry.ZernikeRZToroidalSection`([...])	A toroidal cross section represented by a Zernike polynomial in R,Z.

Grid

`desc.grid.Grid`(nodes[, sort, jitable])	Collocation grid with custom node placement.
`desc.grid.LinearGrid`([L, M, N, NFP, sym, ...])	Grid in which the nodes are linearly spaced in each coordinate.
`desc.grid.QuadratureGrid`(L, M, N[, NFP])	Grid used for numerical quadrature.
`desc.grid.ConcentricGrid`(L, M, N[, NFP, ...])	Grid in which the nodes are arranged in concentric circles.
`desc.grid.find_least_rational_surfaces`(iota, n)	Find "least rational" surfaces for given iota profile.
`desc.grid.find_most_rational_surfaces`(iota, n)	Find "most rational" surfaces for a give iota profile.

IO

`desc.io.InputReader`([cl_args])	Reads command line arguments and parses input files.
`desc.io.load`(load_from[, file_format])	Load any DESC object from previously saved file.

Magnetic Fields

`desc.magnetic_fields.ScaledMagneticField`(...)	Magnetic field scaled by a scalar value.
`desc.magnetic_fields.SumMagneticField`(*fields)	Sum of two or more magnetic field sources.
`desc.magnetic_fields.ToroidalMagneticField`(B0, R0)	Magnetic field purely in the toroidal (phi) direction.
`desc.magnetic_fields.VerticalMagneticField`(B0)	Uniform magnetic field purely in the vertical (Z) direction.
`desc.magnetic_fields.PoloidalMagneticField`(B0, ...)	Pure poloidal magnetic field (ie in theta direction).
`desc.magnetic_fields.SplineMagneticField`(R, ...)	Magnetic field from precomputed values on a grid.
`desc.magnetic_fields.ScalarPotentialField`(...)	Magnetic field due to a scalar magnetic potential in cylindrical coordinates.
`desc.magnetic_fields.field_line_integrate`(r0, ...)	Trace field lines by integration.
`desc.magnetic_fields.read_BNORM_file`(fname, ...)	Read BNORM-style .txt file containing Bnormal Fourier coefficients.
`desc.magnetic_fields.biot_savart`(eval_pts, ...)	Biot-Savart law following [1].

Objective Functions

`desc.objectives.AspectRatio`([eq, target, ...])	Aspect ratio = major radius / minor radius.
`desc.objectives.BootstrapRedlConsistency`([...])	Promote consistency of the bootstrap current for axisymmetry or quasi-symmetry.
`desc.objectives.BScaleLength`([eq, target, ...])	Target a particular value for the magnetic field scale length.
`desc.objectives.CurrentDensity`([eq, target, ...])	Radial, poloidal, and toroidal current density.
`desc.objectives.Elongation`([eq, target, ...])	Elongation = semi-major radius / semi-minor radius.
`desc.objectives.Energy`([eq, target, bounds, ...])	MHD energy.
`desc.objectives.FixAtomicNumber`([eq, ...])	Fixes effective atomic number profile coefficients.
`desc.objectives.FixAxisR`([eq, target, ...])	Fixes magnetic axis R coefficients.
`desc.objectives.FixAxisZ`([eq, target, ...])	Fixes magnetic axis Z coefficients.
`desc.objectives.FixBoundaryR`([eq, target, ...])	Boundary condition on the R boundary parameters.
`desc.objectives.FixBoundaryZ`([eq, target, ...])	Boundary condition on the Z boundary parameters.
`desc.objectives.FixCurrent`([eq, target, ...])	Fixes toroidal current profile coefficients.
`desc.objectives.FixElectronDensity`([eq, ...])	Fixes electron density profile coefficients.
`desc.objectives.FixElectronTemperature`([eq, ...])	Fixes electron temperature profile coefficients.
`desc.objectives.FixIonTemperature`([eq, ...])	Fixes ion temperature profile coefficients.
`desc.objectives.FixIota`([eq, target, ...])	Fixes rotational transform coefficients.
`desc.objectives.FixModeR`([eq, target, ...])	Fixes Fourier-Zernike R coefficients.
`desc.objectives.FixModeZ`([eq, target, ...])	Fixes Fourier-Zernike Z coefficients.
`desc.objectives.FixPressure`([eq, target, ...])	Fixes pressure coefficients.
`desc.objectives.FixPsi`([eq, target, bounds, ...])	Fixes total toroidal magnetic flux within the last closed flux surface.
`desc.objectives.FixSumModesR`([eq, target, ...])	Fixes a linear sum of Fourier-Zernike R coefficients.
`desc.objectives.FixSumModesZ`([eq, target, ...])	Fixes a linear sum of Fourier-Zernike Z coefficients.
`desc.objectives.FixThetaSFL`([eq, name])	Fixes lambda=0 so that poloidal angle is the SFL poloidal angle.
`desc.objectives.ForceBalance`([eq, target, ...])	Radial and helical MHD force balance.
`desc.objectives.GenericObjective`(f[, eq, ...])	A generic objective that can compute any quantity from the data_index.
`desc.objectives.get_equilibrium_objective`([...])	Get the objective function for a typical force balance equilibrium problem.
`desc.objectives.get_fixed_axis_constraints`([...])	Get the constraints necessary for a fixed-axis equilibrium problem.
`desc.objectives.get_fixed_boundary_constraints`([...])	Get the constraints necessary for a typical fixed-boundary equilibrium problem.
`desc.objectives.get_NAE_constraints`(desc_eq, ...)	Get the constraints necessary for fixing NAE behavior in an equilibrium problem.
`desc.objectives.HelicalForceBalance`([eq, ...])	Helical MHD force balance.
`desc.objectives.Isodynamicity`([eq, target, ...])	Isodynamicity metric for cross field transport.
`desc.objectives.MagneticWell`([eq, target, ...])	The magnetic well is a fast proxy for MHD stability.
`desc.objectives.MeanCurvature`([eq, target, ...])	Target a particular value for the mean curvature.
`desc.objectives.MercierStability`([eq, ...])	The Mercier criterion is a fast proxy for MHD stability.
`desc.objectives.ObjectiveFromUser`(fun[, eq, ...])	Wrap a user defined objective function.
`desc.objectives.ObjectiveFunction`(objectives)	Objective function comprised of one or more Objectives.
`desc.objectives.PlasmaVesselDistance`(surface)	Target the distance between the plasma and a surrounding surface.
`desc.objectives.PrincipalCurvature`([eq, ...])	Target a particular value for the (unsigned) principal curvature.
`desc.objectives.QuasisymmetryBoozer`([eq, ...])	Quasi-symmetry Boozer harmonics error.
`desc.objectives.QuasisymmetryTwoTerm`([eq, ...])	Quasi-symmetry two-term error.
`desc.objectives.QuasisymmetryTripleProduct`([...])	Quasi-symmetry triple product error.
`desc.objectives.RadialForceBalance`([eq, ...])	Radial MHD force balance.
`desc.objectives.RotationalTransform`([eq, ...])	Targets a rotational transform profile.
`desc.objectives.ToroidalCurrent`([eq, ...])	Target toroidal current profile.
`desc.objectives.Volume`([eq, target, bounds, ...])	Plasma volume.

Optimize

`desc.optimize.Optimizer`(method)	A helper class to wrap several optimization routines.
`desc.optimize.fmintr`(fun, x0, grad[, hess, ...])	Minimize a scalar function using a (quasi)-Newton trust region method.
`desc.optimize.lsqtr`(fun, x0, jac[, bounds, ...])	Solve a least squares problem using a (quasi)-Newton trust region method.

Perturbations

`desc.perturbations.get_deltas`(things1, things2)	Compute differences between parameters for perturbations.
`desc.perturbations.perturb`(eq, objective, ...)	Perturb an Equilibrium with respect to input parameters.
`desc.perturbations.optimal_perturb`(eq, ...)	Perturb an Equilibrium with respect to input parameters to optimize an objective.

Plotting

`desc.plotting.plot_1d`(eq, name[, grid, log, ...])	Plot 1D profiles.
`desc.plotting.plot_2d`(eq, name[, grid, log, ...])	Plot 2D cross-sections.
`desc.plotting.plot_3d`(eq, name[, grid, log, ...])	Plot 3D surfaces.
`desc.plotting.plot_basis`(basis[, return_data])	Plot basis functions.
`desc.plotting.plot_boozer_modes`(eq[, log, ...])	Plot Fourier harmonics of \(\|B\|\) in Boozer coordinates.
`desc.plotting.plot_boozer_surface`(eq[, ...])	Plot \(\|B\|\) on a surface vs the Boozer poloidal and toroidal angles.
`desc.plotting.plot_boundaries`(eqs[, labels, ...])	Plot stellarator boundaries at multiple toroidal coordinates.
`desc.plotting.plot_boundary`(eq[, phi, ...])	Plot stellarator boundary at multiple toroidal coordinates.
`desc.plotting.plot_coefficients`(eq[, L, M, ...])	Plot spectral coefficient magnitudes vs spectral mode number.
`desc.plotting.plot_coils`(coils[, grid, ax, ...])	Create 3D plot of coil geometry.
`desc.plotting.plot_comparison`(eqs[, rho, ...])	Plot comparison between flux surfaces of multiple equilibria.
`desc.plotting.plot_field_lines_sfl`(eq, rho)	Plots field lines on specified flux surface.
`desc.plotting.plot_fsa`(eq, name[, ...])	Plot flux surface averages of quantities.
`desc.plotting.plot_grid`(grid[, return_data])	Plot the location of collocation nodes on the zeta=0 plane.
`desc.plotting.plot_logo`([save_path])	Plot the DESC logo.
`desc.plotting.plot_qs_error`(eq[, log, fB, ...])	Plot quasi-symmetry errors f_B, f_C, and f_T as normalized flux functions.
`desc.plotting.plot_section`(eq, name[, grid, ...])	Plot Poincare sections.
`desc.plotting.plot_surfaces`(eq[, rho, ...])	Plot flux surfaces.

Profiles

`desc.profiles.PowerSeriesProfile`([params, ...])	Profile represented by a monic power series.
`desc.profiles.SplineProfile`([values, knots, ...])	Profile represented by a piecewise cubic spline.
`desc.profiles.MTanhProfile`([params, grid, name])	Profile represented by a modified hyperbolic tangent + polynomial.
`desc.profiles.ScaledProfile`(scale, profile, ...)	Profile times a constant value.
`desc.profiles.SumProfile`(profiles, *kwargs)	Sum of two or more Profiles.
`desc.profiles.ProductProfile`(profiles, *kwargs)	Product of two or more Profiles.

Transform

desc.transform.Transform(grid, basis[, ...])

Transforms from spectral coefficients to real space values.

VMEC

desc.vmec.VMECIO()

Performs input from VMEC netCDF files to DESC Equilibrium and vice-versa.