Plasma parameters (plasmapy.formulary.parameters)


The plasmapy.formulary.parameters module is deprecated and will be removed in the release of v0.9.0. Please update your code to import directly from plasmapy.formulary or the specific submodule the functionality is defined in. For example,

from plasmapy.formulary import Alfven_speed

# or

from plasmapy.formulary.speeds import Alfven_speed

Functions to calculate fundamental plasma parameters.


Alfven_speed(B, density[, ion, z_mean])

Calculate the Alfvén speed.

Bohm_diffusion(T_e, B)

Return the Bohm diffusion coefficient.

Debye_length(T_e, n_e)

Calculate the characteristic decay length for electric fields,

Debye_number(T_e, n_e)

Return the number of electrons within a sphere with a radius of the Debye length.

gyrofrequency(B, particle[, signed, Z, to_hz])

Calculate the particle gyrofrequency in units of radians per second.

gyroradius(B, particle, *[, Vperp, T_i, T])

Return the particle gyroradius.

Hall_parameter(n, T, B, ion, particle[, ...])

Calculate the particle Hall parameter for a plasma.

inertial_length(n, particle)

Calculate a charged particle's inertial length.

ion_sound_speed(T_e, T_i, ion[, n_e, k, ...])

Return the ion sound speed for an electron-ion plasma.

kappa_thermal_speed(T, kappa, particle[, method])

Return the most probable speed for a particle within a Kappa distribution.

lower_hybrid_frequency(B, n_i, ion[, to_hz])

Return the lower hybrid frequency.


Calculate the magnetic energy density.


Calculate the magnetic pressure.

mass_density(density, particle[, z_ratio])

Calculate the mass density from a number density.

plasma_frequency(n, particle[, z_mean, to_hz])

Calculate the particle plasma frequency.

thermal_pressure(T, n)

Return the thermal pressure for a Maxwellian distribution.

thermal_speed(T, particle[, method, mass, ndim])

Calculate the speed of thermal motion for particles with a Maxwellian distribution.

thermal_speed_coefficients(method, ndim)

Get the thermal speed coefficient corresponding to the desired thermal speed definition.

upper_hybrid_frequency(B, n_e[, to_hz])

Return the upper hybrid frequency.


PlasmaPy provides short-named (alias) versions of the most common plasma functionality. These aliases are only given to functionality where there is a common lexicon in the community, for example plasma_frequency has the alias wp_. All aliases in PlasmaPy are denoted with a trailing underscore _.

cs_(T_e, T_i, ion[, n_e, k, gamma_e, ...])

Alias to ion_sound_speed.

cwp_(n, particle)

Alias to inertial_length.

DB_(T_e, B)

Alias to Bohm_diffusion.

lambdaD_(T_e, n_e)

Alias to Debye_length.

nD_(T_e, n_e)

Alias to Debye_number.

oc_(B, particle[, signed, Z, to_hz])

Alias to gyrofrequency.


Alias to magnetic_pressure.

pth_(T, n)

Alias to thermal_pressure.

rc_(B, particle, *[, Vperp, T_i, T])

Alias to gyroradius.

rho_(density, particle[, z_ratio])

Alias to mass_density.

rhoc_(B, particle, *[, Vperp, T_i, T])

Alias to gyroradius.


Alias to magnetic_energy_density.

va_(B, density[, ion, z_mean])

Alias to Alfven_speed.

vth_(T, particle[, method, mass, ndim])

Alias to thermal_speed().

vth_kappa_(T, kappa, particle[, method])

Alias to kappa_thermal_speed.

wc_(B, particle[, signed, Z, to_hz])

Alias to gyrofrequency.

wlh_(B, n_i, ion[, to_hz])

Alias to lower_hybrid_frequency.

wp_(n, particle[, z_mean, to_hz])

Alias to plasma_frequency.

wuh_(B, n_e[, to_hz])

Alias to upper_hybrid_frequency.


Much of PlasmaPy’s functionality incorporates Astropy units for user convenience and to mitigate calculation errors from inappropriate units, but this comes at the sacrifice of speed. While this penalty is not significant for typical use, it can become substantial during intensive numerical calculations. Lite-functions are introduced for the specific case where speed matters, but [USER NOTICE] this comes with the reduction of safeguards so a user needs to know what they are doing! For additional details look to the glossary entry for lite-function.

plasma_frequency_lite(n, mass, z_mean[, to_hz])

The "lite-function" version of plasma_frequency.

thermal_speed_lite(T, mass, coeff)

The "lite-function" version of thermal_speed.