plasmapy.formulary.speeds.thermal_speed_lite(T: float, mass: float, coeff: float) float[source]

The lite-function for thermal_speed. Performs the same thermal speed calculations as thermal_speed, but is intended for computational use and, thus, has data conditioning safeguards removed.

\[v_{th} = C_o \sqrt{\frac{k_B T}{m}}\]

where \(T\) is the temperature associated with the distribution, \(m\) is the particle’s mass, and \(C_o\) is a constant of proportionality determined by the method in which \(v_{th}\) is calculated and the dimensionality of the system (1D, 2D, 3D). For further details see the Notes section in the thermal_speed documentation.

  • T (float) – The temperature of the particle distribution, in units of kelvin.

  • mass (float) – Mass of the particle in kg.

  • coeff (float) – The coefficient \(C_o\) associated with the method used for calculating the thermal speed, see Notes section in the thermal_speed documentation.


vth – Thermal speed of the Maxwellian distribution in units of m/s.

Return type:



>>> from plasmapy.particles import Particle
>>> mass = Particle("p").mass.value
>>> coeff = thermal_speed_coefficients(method="most_probable", ndim=3)
>>> thermal_speed_lite(T=1e6, mass=mass, coeff=coeff)