Source code for pyrfu.mms.def2psd
#!/usr/bin/env python
# -*- coding: utf-8 -*-
# Built-in imports
from typing import Union
# 3rd party imports
import numpy as np
from scipy import constants
from xarray.core.dataarray import DataArray
from xarray.core.dataset import Dataset
__author__ = "Louis Richard"
__email__ = "louisr@irfu.se"
__copyright__ = "Copyright 2020-2024"
__license__ = "MIT"
__version__ = "2.4.13"
__status__ = "Prototype"
def _mass_ratio(inp):
if inp.attrs["species"].lower() in ["ions", "ion", "protons", "proton"]:
mass_ratio = 1
elif inp.attrs["species"].lower() in ["alphas", "alpha", "helium"]:
mass_ratio = 4
elif inp.attrs["species"].lower() in ["electrons", "e"]:
mass_ratio = constants.electron_mass / constants.proton_mass
else:
raise ValueError("Invalid specie")
return mass_ratio
def _convert(inp, units, mass_ratio):
fact = 1e6 * 0.53707 * mass_ratio**2
if units.lower() in ["kev/(cm^2 s sr kev)", "ev/(cm^2 s sr ev)", "1/(cm^2 s sr)"]:
tmp_data = inp / 1e18 * fact
else:
raise ValueError("Invalid unit")
return tmp_data
[docs]def def2psd(inp: Union[DataArray, Dataset]) -> Union[DataArray, Dataset]:
r"""Compute phase space density from differential energy flux.
The phase-space density is given by:
.. math:
f(E) = m^2 \frac{DEF}{E^2} * 0.53707,
where :math:`m` is the particle mass in atomic mass unit, :math:`DEF` is
the differential energy flux in 1/(cm sr s) and :math:`E` is the energy
in eV.
Parameters
----------
inp : xarray.Dataset or xarray.DataArray
Time series of the differential energy flux in [(cm^{2} s sr)^{-1}].
Returns
-------
psd : xarray.Dataset or xarray.DataArray
Time series of the phase space density in [s^{3} m^{-6}]
Raises
------
TypeError
If inp is not a xarray.Dataset or xarray.DataArray.
"""
if isinstance(inp, Dataset):
tmp_data = _convert(inp.data.data, inp.data.attrs["UNITS"], _mass_ratio(inp))
energy = inp.energy.data
energy_mat = np.tile(energy[:, :, None, None], (1, 1, *tmp_data.shape[2:]))
tmp_data /= energy_mat**2
out = inp.copy()
out.data.data = np.squeeze(tmp_data)
out.data.attrs["UNITS"] = "s^3/m^6"
elif isinstance(inp, DataArray):
tmp_data = _convert(inp.data, inp.attrs["UNITS"], _mass_ratio(inp))
energy = inp.energy.data
energy_mat = np.tile(energy, (tmp_data.shape[0], 1))
tmp_data /= energy_mat**2
out = inp.copy()
out.data = np.squeeze(tmp_data)
out.attrs["UNITS"] = "s^3/m^6"
else:
raise TypeError("Invalid input type")
return out