pyrfu.models.ion_anisotropy_thresh module#

pyrfu.models.ion_anisotropy_thresh.ion_anisotropy_thresh(beta, instability_type, growth_rate='10^-2')[source]#

Compute the threshold using the empirical model defined in [1].

\[R_i = T_{i\perp} / T_{i\parallel} = 1 + a / (\beta_{i\parallel} -\beta_0)^b\]
Parameters:

  • beta (xarray.DataArray or numpy.ndarray) – Time series or array of parallel ion plasma beta.

  • a (float) – Coefficient from fit.

  • b (float) – Coefficient from fit.

  • beta0 (float) – Coefficient from fit.

Returns:

r_i_thresh – Time series or array of threshold temperature anisotropy at the given beta.

Return type:

xarray.DataArray

References

[1]

Hellinger, P., P. Travnicek, J. C. Kasper, and A. J. Lazarus (2006), Solar wind proton temperature anisotropy: Linear theory and WIND/SWE observations, Geophys. Res. Lett., 33, L09101, doi:10.1029/2006GL025925.