Nonlinear Landau damping and growth have been observed for ion-acoustic waves. The measured nonlinear wave-wave coupling coefficients are in reasonable agreement with theory. The forced beat oscillations between the two injected waves, which cause non-linear Landau damping, were also observed.

• Received 21 June 1971

DOI:https://doi.org/10.1103/PhysRevLett.27.718