# Coulomb_cross_section¶

plasmapy.formulary.collisions.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.

Examples

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


Notes

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. Quantity

References

 [1] https://en.wikipedia.org/wiki/Cross_section_(physics)#Collision_among_gas_particles