desc.geometry.FourierRZToroidalSurface.from_qp_model

classmethod FourierRZToroidalSurface.from_qp_model(major_radius=1, aspect_ratio=10, elongation=2, mirror_ratio=0.1, torsion=0, NFP=1, sym=True, positive_iota=True)Source

Create a surface from a near-axis model for quasi-poloidal symmetry.

Parameters:

  • major_radius (float) – Average major radius. Constant term in the R coordinate.

  • aspect_ratio (float) – Aspect ratio of the geometry = major radius / average cross-sectional area.

  • elongation (float) – Elongation of the elliptical surface = major axis / minor axis.

  • mirror_ratio (float) – Mirror ratio generated by toroidal variation of the cross-sectional area. Must be <= 1.

  • torsion (float) – Vertical extent of the magnetic axis Z coordinate. Coefficient of sin(2*phi).

  • NFP (int) – Number of field periods.

  • sym (bool (optional)) – Whether to enforce stellarator symmetry.

  • positive_iota (bool (optional)) – Whether the rotational transform should be positive or negative.

Returns:

surface (FourierRZToroidalSurface) – Surface with given geometric properties.