freeofcharge.beam

Neutral beam markers: fast hydrogen atoms on straight lines.

A marker is a stream of atoms: a position and a velocity (Cartesian, z vertical) and a weight in atoms per second, held in a :class:plasmacoll.ParticleArrays. With MPI every rank holds its own share of the markers.

Classes

Name	Description
NeutralBeam	Neutral markers of one isotope (positions (N, 3), weights in atoms/s).

Functions

Name	Description
tangential_injection	Return the start point and direction of a horizontal beam axis.

NeutralBeamclassdataclass#

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class NeutralBeam(markers: ParticleArrays, mass_number: int)

Neutral markers of one isotope (positions (N, 3), weights in atoms/s).

markersattributeinstance attribute#

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markers: ParticleArrays

mass_numberattributeinstance attribute#

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mass_number: int

Atomic mass number of the beam atoms (1 H, 2 D, 3 T).

directionsproperty#

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directions

Return the unit directions (N, 3).

energiesproperty#

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energies

Return the marker energies [eV].

massproperty#

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mass: float

Return the atom mass [kg].

sizeproperty#

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size: int

Return the number of local markers.

speedsproperty#

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speeds

Return the marker speeds [m/s].

concatenatemethodclassmethod#

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def concatenate(beams: Sequence[NeutralBeam]) -> NeutralBeam

Join beams of one isotope (e.g. energy components).

gaussianmethodclassmethod#

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def gaussian(origin, direction, energy: float, power: float, *, mass_number: int = 2, width: float | tuple[float, float] = 0.0, divergence: float | tuple[float, float] = 0.0, halo_fraction: float = 0.0, halo_divergence: float | tuple[float, float] = 0.0, markers: int = 10000, seed: int | None = None, comm: MPI.Comm | None = None) -> NeutralBeam

Return a mono-energetic beam with Gaussian width and divergence.

The marker positions spread about origin with standard deviation width [m] across the axis, and their directions with standard deviations divergence [rad] in the two planes containing the axis: each a scalar or (horizontal, vertical), horizontal being the plane of the axis and z-normal. A share halo_fraction of the markers has the halo_divergence instead (core and halo, as BBNBI describes a beamlet). The markers are split between the ranks of comm; the weights give power [W] over all of them.

Parameters

Name	Type	Default	Description
origin		required	Centre of the source plane [m].
direction		required	Beam axis (any length).
energy	float	required	Atom energy [eV].
power	float	required	Beam power [W].
mass_number	int	2	Isotope.
width	float | tuple[float, float]	0.0	Source half-width (standard deviation) [m].
divergence	float | tuple[float, float]	0.0	Core divergence (standard deviation) [rad].
halo_fraction	float	0.0	Share of markers in the halo.
halo_divergence	float | tuple[float, float]	0.0	Halo divergence [rad].
markers	int	10000	Number of markers over all ranks.
seed	int | None	None	Seed of the random streams (per rank).
comm	MPI.Comm | None	None	Communicator; serial if None.

powermethod#

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def power(comm: MPI.Comm | None = None) -> float

Return the beam power over all ranks [W].

tangential_injectionfunction#

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def tangential_injection(tangency_radius: float, start_radius: float, *, height: float = 0.0, toroidal_angle: float = 0.0, sense: int = 1) -> tuple[np.ndarray, np.ndarray]

Return the start point and direction of a horizontal beam axis.

The axis is tangent to the circle R = tangency_radius at the toroidal angle toroidal_angle and starts at R = start_radius, at Z = height; sense = +1 points along +phi at the tangency point.