pyrfu.pyrf.pres_anis module

pyrfu.pyrf.pres_anis.pres_anis(p_fac, b_xyz)

Compute pressure anisotropy factor:

\[\mu_0 \frac{P_\parallel - P_\perp}{|\mathbf{B}|^2}\]

Parameters:

• p_fac (xarray.DataArray) – Time series of the pressure tensor in field aligne coordinates.

• b_xyz (xarray.DataArray) – Time series of the background magnetic field.

Returns:

p_anis – Time series of the pressure anisotropy.

Return type:

xarray.DataArray

See also

pyrfu.mms.rotate_tensor

Rotates pressure or temperature tensor into another coordinate system.

Examples

>>> from pyrfu import mms, pyrf

Time interval

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

Spacecraft index

>>> mms_id = 1

Load magnetic field, ion/electron temperature and number density

>>> b_xyz = mms.get_data("B_gse_fgm_srvy_l2", tint, mms_id)
>>> p_xyz_i = mms.get_data("Pi_gse_fpi_fast_l2", tint, mms_id)

Transform pressure tensor to field aligned coordinates >>> p_fac_i = mms.rotate_tensor(p_xyz_i, “fac”, b_xyz)

Compute pressure anistropy

>>> p_anis = pyrf.pres_anis(p_xyz_i, b_xyz)