LANGMUIR PLASMA WAVES

Langmuir waves are longitudinal electrostatic oscillations of electrons in a plasma. Electrons are displaced from equilibrium, and the restoring Coulomb force drives oscillation at the plasma frequency ω_p = √(ne²/ε₀m). The Bohm-Gross dispersion relation: ω² = ω_p² + 3k²v_th² where v_th = √(kT/m) is the thermal velocity. Landau damping damps waves when phase velocity ≈ electron thermal velocity.