plasma_frequency
- plasmapy.formulary.frequencies.plasma_frequency(n: Unit('1 / m3'), particle: str | Integral | Particle | CustomParticle | Quantity, z_mean=None, to_hz=False)
Calculate the particle plasma frequency.
Aliases:
wp_Lite Version:
plasma_frequency_lite- Parameters:
n (
Quantity) – Particle number density in units convertible to m-3.particle (
Particle) – Representation of the particle species (e.g.,"p"for protons,"D+"for deuterium, or"He-4 +1"for singly ionized helium-4). If no charge state information is provided, then the particles are assumed to be singly charged.z_mean (
Real, optional) – The average ionization (arithmetic mean) for the particle species in the plasma. Typically, the charge state will be derived from theparticleargument, but this keyword will override that behavior.
- Returns:
omega_p – The particle plasma frequency in radians per second. Setting keyword
to_hz=Truewill apply the factor of \(1/2π\) and yield a value in Hz.- Return type:
- Raises:
TypeError – If
nis not aQuantityor particle is not of an appropriate type.UnitConversionError – If
nis not in correct units.ValueError – If
ncontains invalid values or particle cannot be used to identify a particle or isotope.
- Warns:
UnitsWarning– If units are not provided, SI units are assumed.
Notes
The particle plasma frequency is
\[ω_{p} = Z |e| \sqrt{\frac{n}{\epsilon_0 m}}\]where \(m\) is the mass of the particle, \(e\) is the fundamental unit of charge, \(Z\) is the average charge state
z_meanof the particle species, \(n\) is the particle number density. This form of the plasma frequency has units of radians / s, but using theto_hzwill apply the factor of \(1/2π\) to give a value in Hz.Examples
>>> from astropy import units as u >>> plasma_frequency(1e19 * u.m**-3, particle='p') <Quantity 4.16329...e+09 rad / s> >>> plasma_frequency(1e19 * u.m**-3, particle='p', to_hz=True) <Quantity 6.62608...e+08 Hz> >>> plasma_frequency(1e19 * u.m**-3, particle='D+') <Quantity 2.94462...e+09 rad / s> >>> plasma_frequency(1e19 * u.m**-3, 'e-') <Quantity 1.78398...e+11 rad / s> >>> plasma_frequency(1e19 * u.m**-3, 'e-', to_hz=True) <Quantity 2.83930...e+10 Hz>
For user convenience
plasma_frequency_liteis bound to this function and can be used as follows.>>> from plasmapy.particles import Particle >>> mass = Particle("p").mass.value >>> plasma_frequency.lite(n=1e19, mass=mass, z_mean=1) 416329... >>> plasma_frequency.lite(n=1e19, mass=mass, z_mean=1, to_hz=True) 662608...