A low-frequency electrostatic plasma wave with ion inertia and a pressure restoring force, usually dominated by electron pressure. Weak ion Landau damping requires the phase velocity to exceed typical ion speeds. Electron Landau damping depends on the electron parallel marginal distribution and need not vanish even when ion damping is absent.
For equal densities of singly charged ions and electrons, a completely degenerate electron equation of state gives . Coupling this restoring force to ion inertia yields the sound speed in the title. If both species are degenerate and , then . Ion resonances are absent, while the electron parallel marginal distribution has a small slope at the phase velocity, producing relative Landau damping of order .
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Ion acoustic waves are a type of sound wave that propagates in a plasma or ionized gas. These waves are characterized by the oscillation of ions and electrons in the medium, and they combine properties of both acoustic waves (which are typically sound waves in fluids) and plasma dynamics. ### Key Features: 1. **Propagation Mechanism**: In ion acoustic waves, the oscillations are primarily due to the motion of ions, while the electrons respond to these oscillations.