First laboratory observation of freely propagating electrostatic waves produced by intense, localized field structures

Freely propagating electrostatic waves (free modes) are observed to be prod uced by intense, localized field structures in laboratory measurements perf ormed in an unmagnetized plasma in a state of strong Langmuir turbulence. T he freely traveling waves conform to the Langmuir dispersion relation and h ave an average frequency which is approximately 11% higher than the average frequency of the localized field structures. The observations are consiste nt with the predictions of strong Langmuir turbulence theory.