inertial_length

Calculate a charged particle’s inertial length.

The inertial length of a particle of species \(s\) is given by

\[d = \frac{c}{ω_{ps}}\]

The inertial length is the characteristic length scale for a particle to be accelerated in a plasma. The Hall effect becomes important on length scales shorter than the ion inertial length.

Aliases: cwp_

Parameters:

n (Quantity) – Particle number density in units convertible to m^-3.
particle (particle-like) – Representation of the particle species (e.g., ‘p+’ for protons, ‘D+’ for deuterium, or ‘He-4 +1’ for singly ionized helium-4).
mass_numb (integer, keyword-only, optional) – The mass number, if not provided in particle.
Z (real number, keyword-only, optional) – The charge number, if not provided in particle.

Returns:

d – The particle’s inertial length in meters.

Return type:

Quantity

Raises:

TypeError – If n is not a Quantity or particle is not a string.
UnitConversionError – If n is not in units of a number density.
ValueError – The particle density does not have an appropriate value.

Warns:

UnitsWarning – If units are not provided and SI units are assumed.

Notes

The inertial length is also known as the skin depth.

Examples

>>> import astropy.units as u
>>> inertial_length(5 * u.m**-3, "He+")
<Quantity 2.02985...e+08 m>
>>> inertial_length(5 * u.m**-3, "e-")
<Quantity 2376534.75... m>