solarwindpy.instabilities.verscharen2016.beta_ani_inst

beta_ani_inst(beta, a=None, b=None, c=None)[source]

Return the anisotropy threshold for a given beta.

Implements Eq. (5) of []:

\[R_p = 1 + \frac{a}{(\beta_{\parallel,p} - c)^b}\]

where $p$ is defined assuming only a single proton population is fit.

Parameters:

beta (array-like) – Parallel proton beta.
a (float) – Fit parameters from Verscharen et al. (2016).
b (float) – Fit parameters from Verscharen et al. (2016).
c (float) – Fit parameters from Verscharen et al. (2016).

Returns:

Threshold anisotropy values.

Return type:

numpy.ndarray

Examples

>>> beta = np.logspace(-2, 2, 5)
>>> beta_ani_inst(beta, a=0.367, b=-0.408, c=0.011)
array([       nan, 1.1367783..., 1.36534751..., 1.93857946..., 3.40240693...])