Törmäysaika
Törmäysaika, or the collision time, is the average time interval between successive collisions experienced by a particle in a system. It is a fundamental quantity in kinetic theory and transport phenomena, providing a link between microscopic interactions and macroscopic properties such as viscosity, diffusion, and thermal conductivity.
In a simple dilute gas of particles that interact as hard spheres, the collision rate per particle
The concept extends beyond ideal gases. In plasmas, collision times are influenced by long-range Coulomb interactions
Relation to spatial scale is given by the mean free path l ≈ ⟨v⟩ τ, where ⟨v⟩ is a