These waves have similarity with ordinary acoustic waves in the sense of being compressional waves. The waves are longitudinal, i.e., their electric field points in the direction of wave propagation. They are space charge waves which produce no currents or magnetic fields. In collisionless plasmas they can be Landau damped by particles moving close to the phase velocity of the wave. In plasmas with temperature gradients the waves refract toward low temperature regions.
Waves can couple and produce broadband turbulence.
Ion acoustic waves are important in many laboratory and space plasmas. In the present laboratory experiment we will excite the waves with oscillating voltages on grids. The density fluctuations are observable in the ac component of the electron saturation current to a Langmuir probe. The spatial properties will be measured with an interferometer circuit. Specifically, the following initial experiments are suggested.