Spiky turbulence generated by a propagating electrostatic wave of finite spatial extent

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Abstract
The excitation of a new type of plasma turbulence consisting of a collection of neighboring localized electric fields of high intensity is investigated. The individual localized fields that constitute the spiky turbulence oscillate at frequencies close to the electron plasma frequency, and their localization is attributed to wave‐trapping inside the self‐consistent density cavities generated by the total ponderomotive force. Unlike previous investigations of this type of nonlinearity, which have dealt almost exclusively with the effects triggered by electromagnetic radiation, the present work studies the turbulence which is generated by a propagating electrostatic wave of finite spatial extent. This type of pump wave may arise naturally in beam‐plasma experiments or in other situations which lead to a finite amplification region. The spiky turbulence is found to evolve in the nonlinear regime out of the linear parametric instabilities that can be excited by such a pump wave. A detailed linear analysis of the relevant linear instabilities is presented, and the results are found to be in good agreement with the direct numerical solution of the model equations of the problem. The nonlinear results of the present calculation show excellent agreement with the recent beam‐plasma experiment of Wong and Quon in which the generation of spiky turbulence has been positively identified.