Mean free path of particles in gaseous medium¶

The mean free path of a gas particle, defined as the average distance the particle travels between consecutive interactions with another particles, depends on the thermodynamical parameters of the gas as well as the interaction cross section.

Notation:

\(k_\text{B}\) (k_B) is boltzmann_constant.

Notes:

Assuming the model of spherical gas molecules, \(\sigma = \pi d^2\), where \(\sigma\) is the cross section and \(d\) is the molecule diameter.

Conditions:

The gas is in a state of thermodynamic equilibrium.

Links:

mean_free_path¶: mean_free_path of particle.

Symbol:: lambda
Latex:: \(\lambda\)
Dimension:: length

pressure¶: pressure of the gas.

Symbol:: p
Latex:: \(p\)
Dimension:: pressure

temperature¶: temperature of the gas.

Symbol:: T
Latex:: \(T\)
Dimension:: temperature

cross_section¶: cross_section of the interaction between the particle and the gas.

Symbol:: sigma
Latex:: \(\sigma\)
Dimension:: area

law¶

lambda = k_B * T / (sqrt(2) * p * sigma)

Latex:: \[\lambda = \frac{k_\text{B} T}{\sqrt{2} p \sigma}\]