plasmapy.formulary.Coulomb_cross_section(impact_param: Unit("m")) -> Unit("m2")

Cross section for a large angle Coulomb collision.

Parameters:impact_param (Quantity) – Impact parameter for the collision.


>>> Coulomb_cross_section(7e-10*u.m)
<Quantity 6.157...e-18 m2>
>>> Coulomb_cross_section(0.5*u.m)
<Quantity 3.141... m2>


The collisional cross-section (see [1] for a graphical demonstration) for a 90 degree Coulomb collision is obtained by

\[\sigma = \pi (2 * \rho_{\perp})^2\]

where \(\rho_{\perp}\) is the distance of closest approach for a 90 degree Coulomb collision. This function is a generalization of that calculation. Please note that it is not guaranteed to return the correct results for small angle collisions.

Returns:The Coulomb collision cross section area.
Return type:Quantity