Coulomb_cross_section

plasmapy.formulary.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.

Returns

sigma – The Coulomb collision cross section area.

Return type

Quantity

Notes

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

\[σ = π (2 * ρ_⟂)^2\]

where \(ρ_⟂\) is the distance of closest approach for a 90° 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.

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>

References

1

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