A technique for experimentally determining growth and decay characteristics of parametrically excited plasma waves is described. The method is based on switching the pump power between two levels and observing the evolution of the excited waves in time. By using a nonlinear phenomenological model, the linear damping frequency and decay rates of the excited waves are found as is a coupling coefficient between the pump and excited waves. Experiments were conducted in the positive column of an argon discharge in a Tonks‐Dattner structure using a microwave pump. Observed damping of the excited ion‐acoustic wave at pressures between 10 and 44 mTorr is shown to be consistent with ionization collisions, while the decay rate is shown to be a linear function of pump power.
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