Plasma Response to Strongly Sheared Flow

Abstract

Laboratory observations of reactively driven plasma waves in the ion-cyclotron frequency range associated with a localized, transverse dc electric field are reported. This wave excitation occurs even when the field-aligned current is negligible, a situation often reported in the space plasma environment. The fluctuation spectrum is broadband in frequency and its peak depends on the magnitude of the dc electric field. Comparison with theory indicates that these waves result from a strong inhomogeneity in the energy density caused by sheared $\mathbf{E}\ifmmode\times\else\texttimes\fi{}\mathbf{B}$ flow.