simsopt.mhd package

Submodules

simsopt.mhd.boozer module

This module provides a class that handles the transformation to Boozer coordinates, and an optimization target for quasisymmetry.

class simsopt.mhd.boozer.Boozer(equil: simsopt.mhd.vmec.Vmec, mpol: int = 32, ntor: int = 32)

Bases: simsopt.core.optimizable.Optimizable

This class handles the transformation to Boozer coordinates.

A Boozer instance maintains a set “s”, which is a registry of the surfaces on which other objects want Boozer-coordinate data. When the run() method is called, the Boozer transformation is carried out on all these surfaces. The registry can be cleared at any time by setting the s attribute to {}.

get_dofs()

This base Optimizable object has no degrees of freedom, so return an empty array

register(s: Union[float, Iterable[float]]) → None

This function is called by objects that depend on this Boozer object, to indicate that they will want Boozer data on the given set of surfaces.

Parameters

s – 1 or more surfaces on which Boozer data will be requested.

run()

Run booz_xform on all the surfaces that have been registered.

set_dofs(x)

This base Optimizable object has no degrees of freedom, so do nothing.

class simsopt.mhd.boozer.Quasisymmetry(boozer: simsopt.mhd.boozer.Boozer, s: Union[float, Iterable[float]], m: int, n: int, normalization: str = 'B00', weight: str = 'even')

Bases: simsopt.core.optimizable.Optimizable

This class is used to compute the departure from quasisymmetry on a given flux surface based on the Boozer spectrum.

J() → Iterable

Carry out the calculation of the quasisymmetry error.

get_dofs()

This base Optimizable object has no degrees of freedom, so return an empty array

set_dofs(x)

This base Optimizable object has no degrees of freedom, so do nothing.

simsopt.mhd.boozer.closest_index(grid: Iterable[float], val: float) → int

Given a grid of values, find the grid point that is closest to an abitrary value.

Parameters

• grid – A list of values.

• val – We will return the index of the closest grid point to this value.

simsopt.mhd.spec module

This module provides a class that handles the SPEC equilibrium code.

class simsopt.mhd.spec.Residue(spec, pp, qq, vol=1, theta=0, s_guess=None, s_min=- 1.0, s_max=1.0, rtol=1e-09)

Bases: simsopt.core.optimizable.Optimizable

Greene’s residue, evaluated from a Spec equilibrum

J()

Run Spec if needed, find the periodic field line, and return the residue

get_dofs()

This base Optimizable object has no degrees of freedom, so return an empty array

set_dofs(x)

This base Optimizable object has no degrees of freedom, so do nothing.

class simsopt.mhd.spec.Spec(filename=None, exe='xspec')

Bases: simsopt.core.optimizable.Optimizable

This class represents the SPEC equilibrium code.

Philosophy regarding mpol and ntor: The Spec object keeps track of mpol and ntor values that are independent of those for the boundary Surface object. If the Surface object has different mpol/ntor values, the Surface’s rbc/zbs arrays are first copied, then truncated or expanded to fit the mpol/ntor values of the Spec object to before Spec is run. Therefore, you may sometimes need to manually change the mpol and ntor values for the Spec object.

get_dofs()

This base Optimizable object has no degrees of freedom, so return an empty array

iota()

Return the rotational transform in the middle of the volume.

run()

Run SPEC, if needed.

set_dofs(x)

This base Optimizable object has no degrees of freedom, so do nothing.

update_resolution(mpol, ntor)

For convenience, to save “.nml”

volume()

Return the volume inside the VMEC last closed flux surface.

simsopt.mhd.spec.nested_lists_to_array(ll)

Convert a ragged list of lists to a 2D numpy array. Any entries that are None are replaced by 0.

This function is applied to the RBC and ZBS arrays in the input namelist.

simsopt.mhd.vmec module

This module provides a class that handles the VMEC equilibrium code.

class simsopt.mhd.vmec.Vmec(filename=None, mpi=None)

Bases: simsopt.core.optimizable.Optimizable

This class represents the VMEC equilibrium code.

__repr__()

Print the object in an informative way.

aspect()

Return the plasma aspect ratio.

get_dofs()

This base Optimizable object has no degrees of freedom, so return an empty array

get_max_mn()

Look through the rbc and zbs data in fortran to determine the largest m and n for which rbc or zbs is nonzero.

iota_axis()

Return the rotational transform on axis

iota_edge()

Return the rotational transform at the boundary

load_wout()

run()

Run VMEC, if needed.

set_dofs(x)

This base Optimizable object has no degrees of freedom, so do nothing.

volume()

Return the volume inside the VMEC last closed flux surface.

Module contents