Landau Damping
The collisionless damping of electrostatic plasma waves caused by energy exchange between wave electric fields and particles moving near wave phase velocity.
Governing formula
γ_L = (π ω_pe³ / (2 k²)) (df₀ / dv)|_(v = ω/k)
SI unit
s⁻¹ (Damping Rate γ)
In depth
Discovered theoretically by Lev Landau in 1946. Particles moving slightly slower than wave phase velocity v_phase = ω/k absorb energy from the wave, while particles moving slightly faster impart energy to the wave. In thermal equilibrium (df/dv < 0), net wave damping occurs without collisions.
Examples in the real world
Collisionless attenuation of Langmuir waves and ion-acoustic waves in space plasmas.