bluemira.equilibria.find_legs

Class and Methods for separatrix legs.

Classes

NumNull

Class for use with LegFlux.

SortSplit

Class for use with LegFlux.

LegFlux

Class for those pesky separatrix legs.

CalcMethod

Class for use with calculate_connection_length function.

Functions

get_legs_length_and_angle(eq, leg_dict[, ...])

Calculates the length of all the divertor legs in a dictionary.

get_single_null_legs(separatrix, delta, o_point, x_points)

get_legs_double_null_xsplit(separatrix, delta, ...)

get_legs_double_null_zsplit(separatrix, delta, ...)

get_leg_list(leg_pair, delta, o_p[, x_p, imin])

Extracts leg/s from given flux line and return as sorted list.

_extract_offsets(→ list)

add_pair_to_dict(sorted_legs, x_p, o_p)

Convert a upper or lower pair of sorted legs into a dictionary.

_extract_leg(flux_line, x_cut, z_cut, delta_x, o_point_z)

Extract legs from a flux surface using a chosen intersection point.

_extract_leg_using_index_value(flux_line, i_cut)

Extract legs from a flux surface using

calculate_connection_length(eq[, ...])

Calculate the parallel connection length from a starting point to a flux-intercepting

Module Contents

class bluemira.equilibria.find_legs.NumNull(*args, **kwds)

Bases: enum.Enum

Inheritance diagram of bluemira.equilibria.find_legs.NumNull

Class for use with LegFlux.

DN

Double Null

SN

Single Null

class bluemira.equilibria.find_legs.SortSplit(*args, **kwds)

Bases: enum.Enum

Inheritance diagram of bluemira.equilibria.find_legs.SortSplit

Class for use with LegFlux.

X

Split the flux in x-direction

Z

Split the flux in z-direction

class bluemira.equilibria.find_legs.LegFlux(eq: bluemira.equilibria.equilibrium.Equilibrium, psi_n_tol: float = 1e-06, delta_start: float = 0.01, rtol: float = 0.001)

Class for those pesky separatrix legs.

Parameters:

  • eq (bluemira.equilibria.equilibrium.Equilibrium) – Input Equilibrium

  • psi_n_tol (float) – The normalised psi tolerance to use

  • delta_start (float) – Search range value for finding LCFS. Will search for the transition from a “closed” to “open” flux surface for normalised flux values between 1 - delta_start and 1 + delta_start.

  • rtol (float) – Relative tolerance used for finding configuration of separatrix split for double null

eq
o_point
x_points
rtol = 0.001
x_range_lcfs
delta
delta_offsets
dx_offsets = None
which_legs()

Determine how to find and sort legs. For a double null this function: - sorts the x-points by lower then upper - keeps the separatrix list sorted by longest then shortest

Returns:

  • n_null – Weather it is single (SN) or double null (DN) Configuration

  • sort_split – How the separatrix has been split. Z - split into Upper and Lower X - split into Inner and Outer

get_leg_offsets(leg_dict)

Expands the leg list if user requires offset flux surfaces.

get_legs(n_layers: int = 1, dx_off: float = 0.0, delta: float | None = None, delta_offsets: float | None = None)

Get separatrix legs.

Parameters:

  • n_layers (int) – Number of flux surfaces to extract for each leg

  • dx_off (float) – Total span in radial space of the flux surfaces to extract

  • delta (float | None) – intersection point x value +- delta is used to find starting point of leg flux see ‘_extract_leg’.

  • delta_offsets (float | None) – intersection point x value +- delta_offsets is used to find starting point of offsets leg flux see ‘_extract_offsets’.

Returns:

Dictionary of separatrix legs (lists of coordinates), with keys: - lower_inner - lower_outer - upper_inner - upper_outer

Return type:

leg_dict

Raises:

EquilibriaError – if a strange number of legs would be found for an X-point:

Notes

Will return two legs in the case of a single null (an upper or lower pair). Will return four legs in the case of a double null.

We can’t rely on the X-point being contained within the two legs, due to interpolation and local minimum finding tolerances.

bluemira.equilibria.find_legs.get_legs_length_and_angle(eq: bluemira.equilibria.equilibrium.Equilibrium, leg_dict: dict[str, numpy.typing.NDArray[numpy.float64] | None], plasma_facing_boundary: bluemira.equilibria.equilibrium.Grid | bluemira.geometry.coordinates.Coordinates | None = None)

Calculates the length of all the divertor legs in a dictionary.

Returns:

  • leg length dictionary for a given leg

  • the angle dictionary for a given leg

Parameters:
bluemira.equilibria.find_legs.get_single_null_legs(separatrix, delta, o_point, x_points, imin=None)
Returns:

The legs from a single null separatrix as a dictionary.

bluemira.equilibria.find_legs.get_legs_double_null_xsplit(separatrix, delta, x_points, o_point)
Returns:

The legs from a double null separatrix, split in x-direction, as a dictionary.

bluemira.equilibria.find_legs.get_legs_double_null_zsplit(separatrix, delta, x_points, o_point, x_range_lcfs)
Returns:

The legs from a double null separatrix, split in z-direction, as a dictionary.

bluemira.equilibria.find_legs.get_leg_list(leg_pair, delta, o_p, x_p=None, imin=None)

Extracts leg/s from given flux line and return as sorted list. Legs are sorted by inner then outer.

Returns:

the legs sort by in and out

Raises:

BluemiraError – if x_p and imin are both None

bluemira.equilibria.find_legs._extract_offsets(eq, ref_leg, direction, o_p, dx_offsets, delta_offsets) → list
Returns:

Flux surfaces offset from separatrix leg

Return type:

list

bluemira.equilibria.find_legs.add_pair_to_dict(sorted_legs, x_p, o_p)

Convert a upper or lower pair of sorted legs into a dictionary.

bluemira.equilibria.find_legs._extract_leg(flux_line: bluemira.geometry.coordinates.Coordinates, x_cut: float, z_cut: float, delta_x: float, o_point_z: float)

Extract legs from a flux surface using a chosen intersection point.

Parameters:

  • flux_line (bluemira.geometry.coordinates.Coordinates) – Coordinates of a flux surface

  • x_cut (float) – a point on the horizontal line (radial_line) that intersects the flux surface, below beyond which the flux surface becomes the legs

  • z_cut (float) – a point on the horizontal line (radial_line) that intersects the flux surface, below beyond which the flux surface becomes the legs

  • delta_x (float) – the width of the radial_line (used for cutting)

  • o_point_z (float) – the approximate height of the o-point (center of the plasma). Used to determine whether the leg being processed in a loop is a top or button of a double-null divertor tokamak.

Returns:

A list of the flux legs

bluemira.equilibria.find_legs._extract_leg_using_index_value(flux_line: bluemira.geometry.coordinates.Coordinates, i_cut: float)

Extract legs from a flux surface using an intersection point chosen by index value.

Returns:

The flux legs

Parameters:
class bluemira.equilibria.find_legs.CalcMethod(*args, **kwds)

Bases: enum.Enum

Inheritance diagram of bluemira.equilibria.find_legs.CalcMethod

Class for use with calculate_connection_length function. User can choose how the connection length is calculated

FIELD_LINE_TRACER
FLUX_SURFACE_GEOMETRY
bluemira.equilibria.find_legs.calculate_connection_length(eq: bluemira.equilibria.equilibrium.Equilibrium, div_target_start_point: bluemira.geometry.coordinates.Coordinates | None = None, first_wall: bluemira.geometry.coordinates.Coordinates | None = None, div_norm_psi: float | None = None, forward: bool = True, psi_n_tol: float = 1e-06, delta_start: float = 0.01, rtol: float = 0.1, n_turns_max: int = 50, n_points: int = 1000, calculation_method: str = 'flux_surface_geometry')

Calculate the parallel connection length from a starting point to a flux-intercepting surface using either flux surface geometry or a field line tracer.

User can choose an xz point or a normalised psi value to select a flux surface of interest - please NOTE, an input div_norm_psi will override an input div_target_start_point if both are entered.

If no starting point is selected then use the separatrix at the Outboard Midplane.

Returns:

The connection length

Raises:

BluemiraError – If an invalid option calculation_method is selected. If an invalid div_norm_psi value is entered. If no target is provided for FLT calculation_method - this is because the flux interception point found is not accurate enough to be used on a separatrix automatically found by bluemira (n.b., the FLT can not distinguish between open and closed flux).

Parameters: