ION BERNSTEIN WAVES DRIVEN BY 2 TRANSVERSE FLOW LAYERS

The interaction between two narrow layers of EXB flow is investigated, along with their stability properties. The mode frequencies, growth r ates, and eigenfunctions are calculated. It is found that the instabil ity due to a single layer is robust to the inclusion of a second layer . Specifically, when the separation between the layers is on the order of the ion-cyclotron radius, there is strong coupling between the two layers and the second layer is destabilizing. In addition, when the f low velocities are in opposite directions a wide variety of modes is p ossible, including near-zero-frequency modes, resulting in broadband s tructure in both the frequency spectrum and the wave number spectrum. These results may have implications for the understanding of the auror al ionosphere, where such spatial structure in the transverse electric field is often observed. (C) 1998 American Institute of Physics. [S10 70-664X(98)03807-5]