desc.magnetic_fields.PoloidalMagneticField

class desc.magnetic_fields.PoloidalMagneticField(B0, R0, iota)Source

Pure poloidal magnetic field (ie in theta direction).

Field strength is B0*iota*r/R0 where B0 is the toroidal field on axis, R0 is the major radius of the axis, iota is the desired rotational transform, and r is the minor radius centered on the magnetic axis.

Combined with a toroidal field with the same B0 and R0, creates an axisymmetric field with rotational transform iota

Note that the divergence of such a field is proportional to Z/R so is generally nonzero except on the midplane, but still serves as a useful test case

Parameters:

• B0 (float) – field strength on axis

• R0 (float) – major radius of magnetic axis

• iota (float) – desired rotational transform

Methods

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.
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.
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.
unpack_params(x)	Convert a single array of concatenated parameters into a dictionary.

Attributes

B0	field strength on axis.
R0	major radius of axis.
dim_x	total number of optimizable parameters.
dimensions	dictionary of integers of sizes of each optimizable parameter.
iota	desired rotational transform.
optimizable_params	string names of parameters that have been declared optimizable.
params_dict	dictionary of arrays of optimizable parameters.
x_idx	arrays of indices for each parameter in concatenated array.