pyrfu.mms.psd_moments module#

pyrfu.mms.psd_moments.psd_moments(vdf, sc_pot, **kwargs)[source]#

Computes moments from the FPI particle phase-space densities.

Parameters:

  • vdf (xarray.Dataset) – 3D skymap velocity distribution.

  • sc_pot (xarray.DataArray) – Time series of the spacecraft potential.

  • energy_range (array_like) – Set energy range in eV to integrate over [E_min E_max]. Energy range is applied to energy0 and the same elements are used for energy1 to ensure that the same number of points are integrated over.

  • no_sc_pot (bool) – Set to 1 to set spacecraft potential to zero. Calculates moments without correcting for spacecraft potential.

  • en_channels (array_like) – Set energy channels to integrate over [min max]; min and max between must be between 1 and 32.

  • partial_moments (numpy.ndarray or xarray.DataArray) – Use a binary array to select which psd points are used in the moments calculation. partial_moments must be a binary array (1s and 0s, 1s correspond to points used). Array (or data of Dataarray) must be the same size as vdf.data.

  • inner_electron ({"on", "off"}) – inner_electrontron potential for electron moments.

Returns:

  • n_psd (xarray.DataArray) – Time series of the number density (1rst moment).

  • v_psd (xarray.DataArray) – Time series of the bulk velocity (2nd moment).

  • p_psd (xarray.DataArray) – Time series of the pressure tensor (3rd moment).

  • p2_psd (xarray.DataArray) – Time series of the pressure tensor.

  • t_psd (xarray.DataArray) – Time series of the temperature tensor.

  • h_psd (xarray.DataArray) – to fill.

Examples

>>> from pyrfu import mms

Define time interval

>>> tint_brst = ["2015-10-30T05:15:20.000", "2015-10-30T05:16:20.000"]

Load magnetic field and spacecraft potential

>>> scpot = mms.get_data("V_edp_brst_l2", tint_brst, 1)

Load electron velocity distribution function

>>> vdf_e = mms.get_data("pde_fpi_brst_l2", tint_brst, 1)

Compute moments

>>> options = dict(energy_range=[1, 1000])
>>> moments_e = mms.psd_moments(vdf_e, scpot, **options)