Spontaneous Electromagnetic Emission from a Strongly Localized Plasma Flow

Laboratory observations of electromagnetic ion cyclotron waves generated by a localized transverse dc electric field are reported. Experiments indicate that these waves result from a strong \textbf{E}$\times $\textbf{B} flow inhomogeneity in a mildly collisional plasma with sub-critical magnetic field-aligned current. The wave amplitude scales with the magnitude of the applied radial dc electric field. The electromagnetic signatures become stronger with increasing plasma $\beta $, and the radial extent of the power is larger than that of the electrostatic counterpart.