freeofcharge.deposition

Deposition of a neutral beam in the plasma: births and shine-through.

Every marker flies on a straight line from its position. Along it the line is cut into steps of length ds; at each step’s midpoint inside the last closed flux surface the optical depth grows by n_e sigma_s ds, so the stream left after step k is w exp(-tau_k) and step k ionises w (exp(-tau_{k-1}) - exp(-tau_k)) atoms per second. Those are tallied on shells of rho (the birth profile, without sampling noise). Births are then sampled: for each of births_per_marker draws, the depth tau* where the cumulative ionised share reaches a uniform random fraction, the birth point by linear interpolation of tau within its step, and the weight w (1 - exp(-tau_total)) / births_per_marker. A fast ion starts with the atom’s velocity.

With a first wall, a line enters the vessel at the first step inside the wall and ends at the first step after that outside it: the shine-through hits the wall there (to within ds). Without a wall the line runs to its end.

Charge exchange is part of sigma_s: an ion that becomes a fast neutral again counts as stopped, not followed.

Classes

Name	Description
Deposition	The fast ions born in the plasma and the beam that shines through.

Functions

Name	Description
deposit	Return the deposition of beam in the plasma.

Depositionclassdataclass#

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class Deposition(births: ParticleArrays, birth_rho: object, birth_pitch: object, mass_number: int, rho_edges: np.ndarray, birth_rate: np.ndarray, power: np.ndarray, injected_power: float, absorbed_power: float, shine_through_power: float, wall_hits: ParticleArrays | None)

The fast ions born in the plasma and the beam that shines through.

The profiles and powers are sums over all ranks; the births and wall hits are this rank’s.

absorbed_powerattributeinstance attribute#

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absorbed_power: float

birth_pitchattributeinstance attribute#

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birth_pitch: object

v_par / v of each birth (positive along B).

birth_rateattributeinstance attribute#

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birth_rate: np.ndarray

Ions born per second in each shell.

birth_rhoattributeinstance attribute#

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birth_rho: object

rho of each birth.

birthsattributeinstance attribute#

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births: ParticleArrays

Birth positions (N, 3), velocities and weights [ions/s].

injected_powerattributeinstance attribute#

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injected_power: float

mass_numberattributeinstance attribute#

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mass_number: int

powerattributeinstance attribute#

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power: np.ndarray

Beam power deposited in each shell [W].

rho_edgesattributeinstance attribute#

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rho_edges: np.ndarray

shine_through_powerattributeinstance attribute#

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shine_through_power: float

wall_hitsattributeinstance attribute#

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wall_hits: ParticleArrays | None

Where the shine-through meets the wall: positions, velocities, weights [atoms/s]; None without a wall.

shine_through_fractionproperty#

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shine_through_fraction: float

Return the share of the injected power that is not absorbed.

power_densitymethod#

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def power_density(surfaces: FluxSurfaces) -> np.ndarray

Return the deposited power per volume of each shell [W/m^3].

to_datasetmethod#

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def to_dataset(surfaces: FluxSurfaces | None = None) -> xr.Dataset

Return the profiles on the shell centres, with densities if surfaces.

depositfunction#

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def deposit(beam: NeutralBeam, equilibrium: Equilibrium, plasma: Plasma, stopping: StoppingModel | None = None, *, step: float = 0.01, rho_edges=None, births_per_marker: int = 1, max_length: float | None = None, seed: int | None = None, comm: MPI.Comm | None = None, chunk_points: int = 2000000) -> Deposition

Return the deposition of beam in the plasma.

Parameters

Name	Type	Default	Description
beam	NeutralBeam	required	This rank’s markers.
equilibrium	Equilibrium	required	Flux, boundary and (optional) wall.
plasma	Plasma	required	Profiles.
stopping	StoppingModel | None	None	Stopping model; :class:SuzukiStopping if None.
step	float	0.01	Step ds along the lines [m].
rho_edges		None	Shells of the profiles; 50 equal ones if None.
births_per_marker	int	1	Births sampled per marker (0 for profiles only).
max_length	float | None	None	Length of the lines [m]; long enough to cross the grid if None.
seed	int | None	None	Seed of the birth sampling (per rank).
comm	MPI.Comm | None	None	Communicator over which the markers are split; serial if None.
chunk_points	int	2000000	Line points held at once (memory).