1

How to calculate the free mean path of electrons in the gas mixture? I understand (a little bit) the mean free path concept for the atomic collisions but I am not sure what to do if I am interested in the electrons only. Is it different for a whole atom and a single electron?

The mean free path is generally defined as: $\lambda = \frac{1}{n\pi r^2}$ where $r$ is the diameter of the atom and $n$ is the number density of the particles.

I have seen so many different equations on the internet for the electron mean path but I am so confused, I really don't understand it. So any help would be really appreciated.

honeste_vivere
  • 15,592
  • You are talking about a gas where electrons bound to atoms or about plasma? In the former case the question doesn't make much sense or implies some very specific conditions (like additional electrons injected.) – Roger V. Nov 14 '23 at 14:28

1 Answers1

0

First you calculate the Coulomb collision rates (e.g., see https://physics.stackexchange.com/a/268594/59023), $\nu_{ss'}$, then you take the rms thermal speed between the two colliding species, $V_{Tss'}$, and divide it by the collision rates to get the mean free path, $\lambda_{s} = \frac{ V_{Tss'} }{ \nu_{ss'} }$, of species $s$ propagating through species $s'$.

Note this is all purely statistical. That is, the collision rates are a statistical measure of the expected number of $90^{\circ}$ deflections a particle will experience per unit time. It's not an exact value for every particle, it's just a statistical expectation.

honeste_vivere
  • 15,592