desc.grid.ConcentricGrid.spacing

property ConcentricGrid.spacingSource

Quadrature weights for integration over surfaces.

This is typically the distance between nodes when NFP=1, as the quadrature weight is by default a midpoint rule. The returned matrix has three columns, corresponding to the radial, poloidal, and toroidal coordinate, respectively. Each element of the matrix specifies the quadrature area associated with a particular node for each coordinate. I.e. on a grid with coordinates of “rtz”, the columns specify dρ, dθ, dζ, respectively. An integration over a ρ flux surface will assign quadrature weight dθ*dζ to each node. Note that dζ is the distance between toroidal surfaces multiplied by NFP.

On a LinearGrid with duplicate nodes, the columns of spacing no longer specify dρ, dθ, dζ. Rather, the product of each adjacent column specifies dρ*dθ, dθ*dζ, dζ*dρ, respectively.

Returns:

spacing (ndarray) – Quadrature weights for integration over surface.