Spontaneous Emission of Alfvenic Branch Oscillations From a Strong Inhomogeneous Plasma Flow

Laboratory observations of spontaneous emission of Alfvenic branch oscillations generated by a strong inhomogeneous plasma flow are reported in this work. Electrostatic KH instabilities in the subcyclotron frequency range were excited using the interpenetrating plasma method. Experiments indicate that spontanegeous Alfvenic branch oscillations occur when the plasma inhomogeneity increases above a threshold. The electromagnetic wave amplitude spreads out radially over a much larger extent than the electrostatic mode. Theoretical calculations using the MHD method also support the experimental observation. The result has important application in understanding the cross-scale transport of particles and energies in astrophysical, space, and laboratory plasmas.