desc.grid.ConcentricGrid

class desc.grid.ConcentricGrid(L, M, N, NFP=1, sym=False, axis=False, node_pattern='jacobi')Source

Grid in which the nodes are arranged in concentric circles.

Nodes are arranged concentrically within each toroidal cross-section, with more nodes per flux surface at larger radius. Typically used as the solution grid, cannot be easily used for plotting due to non-uniform spacing.

Parameters:

• L (int) – radial grid resolution

• M (int) – poloidal grid resolution

• N (int) – toroidal grid resolution

• NFP (int) – number of field periods (Default = 1)

• sym (bool) – True for poloidal up/down symmetry, False otherwise. Default is False. Whether to truncate the poloidal domain to [0, π] ⊂ [0, 2π) to take advantage of poloidal up/down symmetry, which is a stronger condition than stellarator symmetry. Still, when stellarator symmetry exists, flux surface integrals and volume integrals are invariant to this truncation.

• axis (bool) – True to include the magnetic axis, False otherwise (Default = False)

• node_pattern ({'cheb1', 'cheb2', 'jacobi', linear}) –

  pattern for radial coordinates

  • 'cheb1': Chebyshev-Gauss-Lobatto nodes scaled to r=[0,1]

  • 'cheb2': Chebyshev-Gauss-Lobatto nodes scaled to r=[-1,1]

  • 'jacobi': Radial nodes are roots of Shifted Jacobi polynomial of degree M+1 r=(0,1), and angular nodes are equispaced 2(M+1) per surface

  • 'ocs': optimal concentric sampling to minimize the condition number of the resulting transform matrix, for doing inverse transform.

  • linear : linear spacing in r=[0,1]

Methods

change_resolution(L, M, N[, NFP])	Change the resolution of the grid.
compress(x[, surface_label])	Return elements of x at indices of unique surface label values.
copy([deepcopy])	Return a (deep)copy of this object.
copy_data_from_other(x, other_grid[, ...])	Copy data x from other_grid to this grid at matching surface label.
equiv(other)	Compare equivalence between DESC objects.
expand(x[, surface_label])	Expand x by duplicating elements to match the grid's pattern.
get_label(label)	Get general label that specifies direction given label.
load(load_from[, file_format])	Initialize from file.
meshgrid_flatten(x, order)	Flatten data to match standard ordering.
meshgrid_reshape(x, order)	Reshape data to match grid coordinates.
replace_at_axis(x, y[, copy])	Replace elements of x with elements of y at the axis of grid.
save(file_name[, file_format, file_mode])	Save the object.

Attributes

L	Radial grid resolution.
M	Poloidal grid resolution.
N	Toroidal grid resolution.
NFP	Number of (toroidal) field periods.
axis	Indices of nodes at magnetic axis.
can_fft2	Whether this grid is compatible with 2D FFT.
coordinates	Coordinates specified by the nodes.
fft_poloidal	whether this grid is compatible with fft in the poloidal direction.
fft_toroidal	whether this grid is compatible with fft in the toroidal direction.
inverse_alpha_idx	Indices that recover field line poloidal angles.
inverse_poloidal_idx	Indices that recover the unique poloidal coordinates.
inverse_rho_idx	Indices of unique_rho_idx that recover the rho coordinates.
inverse_theta_PEST_idx	Indices that recover unique straight field line poloidal angles.
inverse_theta_idx	Indices that recover unique theta coordinates.
inverse_zeta_idx	Indices of unique_zeta_idx that recover the zeta coordinates.
is_meshgrid	Whether this grid is a tensor-product grid.
node_pattern	Pattern for placement of nodes in (rho,theta,zeta).
nodes	Node coordinates, in (rho,theta,zeta).
num_alpha	Number of unique field line poloidal angles.
num_nodes	Total number of nodes.
num_poloidal	Number of unique poloidal angle coordinates.
num_rho	Number of unique rho coordinates.
num_theta	Number of unique theta coordinates.
num_theta_PEST	Number of unique straight field line poloidal angles.
num_zeta	Number of unique zeta coordinates.
period	Periodicity of coordinates.
spacing	Quadrature weights for integration over surfaces.
sym	True for poloidal up/down symmetry, False otherwise.
unique_alpha_idx	Indices of unique field line poloidal angles.
unique_poloidal_idx	Indices of unique poloidal angle coordinates.
unique_rho_idx	Indices of unique rho coordinates.
unique_theta_PEST_idx	Indices of unique straight field line poloidal angles.
unique_theta_idx	Indices of unique theta coordinates.
unique_zeta_idx	Indices of unique zeta coordinates.
weights	Weight for each node, either exact quadrature or volume based.