desc.grid.ConcentricGrid

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

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 stellarator symmetry, False otherwise (Default = False)

• 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.
copy([deepcopy])	Return a (deep)copy of this object.
eq(other)	Compare equivalence between DESC objects.
load(load_from[, file_format])	Initialize from file.
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.
inverse_rho_idx	Indices of unique_rho_idx that recover the rho coordinates.
inverse_theta_idx	Indices of unique_theta_idx that recover the theta coordinates.
inverse_zeta_idx	Indices of unique_zeta_idx that recover the zeta coordinates.
node_pattern	Pattern for placement of nodes in (rho,theta,zeta).
nodes	Node coordinates, in (rho,theta,zeta).
num_nodes	Total number of nodes.
num_rho	Number of unique rho coordinates.
num_theta	Number of unique theta coordinates.
num_zeta	Number of unique zeta coordinates.
spacing	Node spacing, in (rho,theta,zeta).
sym	True for stellarator symmetry, False otherwise.
unique_rho_idx	Indices of unique rho coordinates.
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.