# critical_density

Calculate the plasma critical density for a radiation of a given frequency.

Parameters

omega (Quantity) – The radiation frequency in units of angular frequency.

Returns

n_c – The plasma critical density.

Return type

Quantity

Notes

The critical density for a given frequency of radiation is defined as the value at which the electron plasma frequency equals the frequency of the radiation.

The critical density is given by the formula

$n_{c}=\frac{m_{e}\varepsilon_0\omega^{2}}{e^{2}}$

where $$m_{e}$$ is the mass of an electron, $$\varepsilon_0$$ is the permittivity of free space, $$\omega$$ is the radiation frequency, and $$e$$ is the elementary charge.

Examples

>>> from astropy import units as u