plasmapy.formulary.Wigner_Seitz_radius(n: Unit("1 / m3")) -> Unit("m")

Calculate the Wigner-Seitz radius, which approximates the inter- particle spacing. It is the radius of a sphere whose volume is equal to the mean volume per atom in a solid. This parameter is often used to calculate the coupling parameter. When ion density is used, this is the ion sphere radius, i.e., the space occupied by a single ion with no other ions in that space. Higher density means less space for each ion, so the radius is smaller.

Parameters: n (Quantity) – Particle number density. radius – The Wigner-Seitz radius in meters. Quantity TypeError – If argument is not a ~astropy.units.Quantity. UnitConversionError – If argument is in incorrect units. ValueError – If argument contains invalid values. ~astropy.units.UnitsWarning – If units are not provided, SI units are assumed.

Notes

The Wigner-Seitz radius approximates the interparticle spacing. It is the radius of a sphere whose volume is equal to the mean volume per atom in a solid:

$r = \left(\frac{3}{4 \pi n}\right)^{1/3}$

Example

>>> from astropy import units as u