# Coulomb_cross_section¶

plasmapy.transport.collisions.Coulomb_cross_section(impact_param: Unit("m"))

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 6.1575216e-18 m2>
>>> Coulomb_cross_section(0.5*u.m)
<Quantity 3.14159265 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.

Return type

Quantity

References

1

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