SDFResults

EPOCH is a code for plasma physics simulations using the Particle-in-Cell method. The simulation results are written is .sdf binary files. Several readers for this files are available at https://cfsa-pmw.warwick.ac.uk/SDF. This package intends to help users read and analyse EPOCH simulations.

Install the package using

]add SDFResults

Assuming that you have a folder with .sdf files generated from an EPOCH simulation, use read_simulation to read the metadata for the simulation. You can index into the resulting object and access individual simulation files. Note that by default EPOCH starts indexing form 0, while in Julia we usually start from 1.

using SDFReader

dir = "my_simulation"
sim = read_simulation(dir)
sim[1] # corresponds to the first sdf file (usually 0000.sdf).

With the keys function you can observe what data was saved in the simulation. The symbols correspond to the names used for the saved variables. Note that some identifiers used by EPOCH, such as the ones for species properties are not valid julia symbols (such as px/electron), so instead you can use strings (e.g. "px/electron").

keys(sim[1])

In order to read the data for scalar field quantities such as :ex or "px/electron", you can simply index into the file

file = sim[1]
Ex = file[:ex]

The returned object will be a ScalarField (or ScalarVariable for the components of particle variables such as "px/electron") and will contain the information regarding the data (with units via Unitful.jl) and the corresponding coordinate values. These objects are AbstractArrays and via indexing you can access the stored values.

You can use broadcasting to compute derived quantities. For example, to compute the x component of the angular momentum you can simply use

function compute_Lx(file)
    w, r, py, pz = file["weight/electron",
                        "grid/electron",
                        "py/electron",
                        "pz/electron"]

    y = r[2]
    z = r[3]
    Lx = @. w * (y * pz - z * py)
end

You can also acces the (simulation) time corresponding to a file with

get_time(file)

and also the parameters from the input.deck file with get_parameter. The input.deck parser only supports simple key=value expressions (no arithmetic operations or function calls). You can also access nested values by providing a second argument.

nx = get_parameter(file, :nx)
λ = get_parameter(file, :laser, :lambda)